This application is a Continuation of nonprovisional U.S. application Ser. No. 11/098,516 filed on Apr. 5, 2005. Priority is claimed based on U.S. application Ser. No. 11/098,516 filed on Apr. 5, 2005, which claims the priority of Japanese Application 2004-115337 filed on Apr. 9, 2004, all of which is incorporated by reference.
1. Field of the Invention
The present invention relates to a display device.
2. Description of the Related Art
A display device has tasks which have to be steadily improved such as the enhancement of brightness, the improvement of a viewing angle, the enhancement of image quality, the enhancement of a yield rate, the enhancement of reliability, the enhancement of productivity, the reduction of cost and the like. Here, with respect to the improvement of the viewing angle, for example, U.S. Pat. No. 6,256,081 disclose a display device which sets the directions of electrodes in a plurality of directions in the inside of one pixel or U.S. Pat. No. 6,456,351 disclose a display device in which the directions of electrodes are made different in three pixels which are arranged close to each other in the lateral direction.
As has been explained in the Description of the Related Art, the display device has the various tasks which have to be steadily improved. Among these tasks, with respect to the viewing angle, for example, inventors of the present invention have found out that the structure shown in U.S. Pat. No. 6,256,081 generates an invalid region on a center portion of a pixel and lowers the brightness. Further, the inventors of the present invention have found out that the arrangement of the U.S. Pat. No. 6,456,351 exhibits an insufficient viewing angle at the time of displaying a monochroic color corresponding to a color filter of red, green or blue.
The present invention has been made under such circumstances, for example, and one of advantages of the present invention is to provide a display device which can enhance a viewing angle and can realize the enhancement of brightness in both of a white display and a monochroic display.
Although there are many other tasks and advantages which the present invention aims to achieve, these tasks and advantages will become apparent by the disclosure made in this specification and attached drawings.
To briefly explain the inventions disclosed in this specification, they are as follows.
(1) In a display device having a display element, for example, the display element is configured such that the extending directions of electrodes are made different from each other among upper, lower, left and right pixels.
(2) On the premise of the constitution (1), the extending direction of the electrodes in each pixel is unidirectional.
(3) On the premise of the constitution (1) or (2), the pixels include two types of pixels in which the extending directions of the electrodes are symmetrical with respect to the gate-signal-line extending direction or the video-signal-line extending direction, and the pixels are alternately arranged in the upper, lower, left and right directions.
(4) On the premise of any one of the constitutions (1) to (3), the display element includes color filters having three primary colors and the color filters are arranged such that the color filters of the same color are arranged in the longitudinal direction of the display device and the color filters of three primary colors are sequentially arranged in the lateral direction of the display device.
(5) In a display device having a display element, for example, the display element includes lower planar electrodes and upper electrodes each of which has a large number of line-like portions or slit portions which are formed on a same substrate, and the extending directions of the large number of line-like portions or slit portions are made different from each other among upper, lower, left and right pixels.
(6) On the premise of the constitution (5), the extending direction of the line-like portions and the slit portions in each pixel is unidirectional.
(7) On the premise of the constitution (5) or (6), the pixels include two types of pixels in which the extending directions of the line-like portions or the slit portions are symmetrical with respect to the gate-signal-line extending direction or the video-signal-line extending direction, and the pixels are alternately arranged in the upper, lower, left and right directions.
(8) On the premise of any one of the constitutions (5) to (7), the display element includes color filters having three primary colors and the color filters are arranged such that the color filters of the same color are arranged in the longitudinal direction of the display device and the color filters of three primary colors are sequentially arranged in the lateral direction of the display device.
The display device having such constitutions can enhance a viewing angle and can enhance the brightness in both of a white display and a monochroic display.
Other advantageous effects which are realized by other constitutions of the display device disclosed in this specification will become apparent based on the disclosure in this specification and attached drawings.
FIG. 1 is a plan view for explaining an arrangement example of a group of pixels of a display device according to the present invention;
FIG. 2A and FIG. 2B are views for explaining an example of a pixel pattern of the display device according to the present invention;
FIG. 3 is an explanatory view of an example of the correspondence between color filters and a group of pixels of the display device according to the present invention;
FIG. 4 is an explanatory view of an example of the correspondence between color filters and a group of pixels of the display device according to the present invention;
FIG. 5 is a plan view for explaining an example of a group of pixels of a display device according to the present invention;
FIG. 6A and FIG. 6B are plan views for explaining an example of a group of pixels of a display device according to the present invention;
FIG. 7 is a plan view for explaining an example of a group of pixels of a display device according to the present invention;
FIG. 8A and FIG. 8B are an explanatory view of an embodiment of the arrangement and the orientation direction of a polarizer;
FIG. 9 is an explanatory view of one example of the detailed structure of the pixel of the display device according to the present invention;
FIG. 10 is a an explanatory view of one example of the detailed structure of the pixel of the display device according to the present invention;
FIG. 11 is a schematic cross-sectional view of an A-A′ portion in FIG. 9 or FIG. 10;
FIG. 12A and FIG. 12B are views for explaining the getting-over at an overlapped portion of an electrode and a line;
FIG. 13 is a schematic cross-sectional view of a B-B′ portion in FIG. 9 or FIG. 10;
FIG. 14 is a schematic cross-sectional view of a C-C′ portion in FIG. 9 or FIG. 10;
FIG. 15 is a schematic cross-sectional view of a D-D′ portion in FIG. 9 or FIG. 10;
FIG. 16A and FIG. 16B are explanatory views of a display region and a dummy pixel region;
FIG. 17 is a schematic explanatory view for explaining the arrangement of pixels at corner portions;
FIG. 18A, FIG. 18B, FIG. 18C and FIG. 18D are explanatory views for explaining the arrangement of electrodes of the pixels at the corner portions;
FIG. 19 is an explanatory view of an example of the dummy pixel region;
FIG. 20A and FIG. 20B are schematic cross-sectional views taken along a line A-A′ and a line B-B′ in FIG. 19;
FIG. 21 is an explanatory view of an arrangement example of a dummy pattern in a dummy pixel region;
FIG. 22 is a plan view of the arrangement example of the dummy pattern in a dummy pixel region;
FIG. 23A and FIG. 23B are cross-sectional views for explaining an example of a dummy pattern;
FIG. 24A and FIG. 24B are cross-sectional views for explaining an example of a dummy pattern;
FIG. 25A and FIG. 25B are cross-sectional views for explaining an example of a dummy pattern;
FIG. 26 is a view for explaining a schematic example of a system of a display device
FIG. 27 is an exploded perspective view showing one example of the module structure of the display device;
FIG. 28A to FIG. 28E are views of the module of the display device as viewed from a front side, an upper side, a lower side, a left side and a right side in a state that the display device includes an upper frame
FIG. 29 is a view of the module of the display device as viewed from a back surface;
FIG. 30A to FIG. 30E are views of the module of the display device as viewed from a back surface, a front surface, and upper, lower, left and right side surfaces in a state that a TCON cover, an inverter cover and an upper frame are removed;
FIG. 31 is a view of the module of the display device from a front surface in a state that the upper frame is removed;
FIG. 32 is a perspective view of the module of the display device in a state that the upper frame is removed;
FIG. 33 is a perspective view for explaining the fitting relationship of the upper frame, an intermediate frame and a lower frame;
FIG. 34 is a perspective view for explaining the fitting relationship of the upper frame, the intermediate frame and the lower frame;
FIG. 35A to FIG. 35E are views for explaining the fitting relationship at a portion A in FIG. 34 in more detail;
FIG. 36A and FIG. 366B are views for explaining the positioning at a portion B in FIG. 34 in more detail;
FIG. 37 is an exploded perspective view showing the parts constitution of the intermediate frame;
FIG. 38A and FIG. 38B are a front view and an side view of the vicinity of a drain printed circuit board in a state that the upper frame is removed;
FIG. 39A to FIG. 39C are a front view and side views of one corner portion of the module in a state that the upper frame is removed;
FIG. 40 is a view for explaining the holding structure of a cable;
FIG. 41A and FIG. 41B are explanatory views of a divided drain printed circuit board;
FIG. 42A to FIG. 42D are explanatory views showing the schematic cross-sectional structure of the module of the display device;
FIG. 43A to FIG. 43C are explanatory views of a fixing method of a cover of a display device;
FIG. 44A to FIG. 44D are views showing a constitutional example of a backlight portion;
FIG. 45 is an explanatory view of the arrangement positions of common spacers;
FIG. 46 is a view for explaining a schematic example of a system of the display device:
FIG. 47 is an explanatory view showing an example of predetermined values of a data set;
FIG. 48 is an explanatory view showing an example of the relationship between the data set and the gray scale-brightness characteristics;
FIG. 49 is an explanatory view of rising sequences of a driver power source and a gray scale reference power source;
FIG. 50A to FIG. 50F are explanatory views showing various screen display examples in an information display mode;
FIG. 51A and FIG. 51B are explanatory views showing an example of a technique for changing over to the information display mode;
FIG. 52 is an explanatory view showing the connection of a display element CEL, a tape carrier TCP and a printed circuit board PCB;
FIG. 53A to FIG. 53C are explanatory views on the measurement of the connection resistance between the tape carrier TCP and a printed circuit board PCB;
FIG. 54A and FIG. 54B are explanatory view on the measurement of the connection resistance between the tape carrier TCP and the display element CEL;
FIG. 55A and FIG. 55B are explanatory view on the measurement of the connection resistance between the tape carriers TCP and the display element CEL by way of a plurality of tape carriers TCP;
FIG. 56A and FIG. 56B are schematic connection views of the printed circuit board PCB, the tape carrier TCP and the display element CEL in a state that a connection resistance measurement pattern is incorporated;
FIG. 57A to FIG. 57C are explanatory views of an example of the measurement of the connection resistance between the tape carrier TCP and the printed circuit board PCB;
FIG. 58A to FIG. 58C are explanatory views of an example of the measurement of the connection resistance between the tape carrier TCP and the display element CEL;
FIG. 59 is a system diagram showing the signal transmission between a TCON and a memory;
FIG. 60 is a flow chart of a mode change;
FIG. 61 is an explanatory view of the mode changeover timing;
FIG. 62 is an explanatory view of one example of the detailed structure of the pixel of the display device according to the present invention;
FIG. 63 is an explanatory view of one example of the detailed structure of the pixel of the display device according to the present invention; and
FIG. 64 is an explanatory view of one example of the detailed structure of the pixel of the display device according to the present invention.
Embodiments of the present invention are explained hereinafter in conjunction with drawings.
<Overall Schematic Constitution>
A display device according to the present invention includes a display element as a constitutional element thereof. FIG. 27 is an explode perspective view showing one example of the module structure of the display device. The display element CEL is positioned between an upper frame UFM and a lower frame LFM. The upper frame UFM includes an opening portion and a display region DR of the display element CEL is exposed from the opening portion so that the display region DR can be observed. As an example, when the display element CEL is a liquid crystal display element, a backlight unit BL which becomes a light source of light to be transmitted through the display element CEL is arranged on a back surface of the liquid crystal display element. An intermediate frame MFM is arranged on a peripheral portion of the backlight unit BL and a peripheral portion of the display element CEL is positioned on the intermediate frame MFM thus determining the position of the display element CEL. In the display device, a controller TCON which generates various signals for realizing an image display on the display element CEL is provided.
FIG. 26 is a system schematic diagram showing a path for generating a display signal to the display element CEL in response to a signal from the controller TCON. Signals from the outside of the display device, for example, a signal from a TV set, a signal from a PC and other various control signals are inputted to the controller TCON as an external output OI. The controller TCON forms such signals into signals to be supplied to the display element CEL for an image display. The signals differ depending on the display element CEL. For example, the various control signals are formed into desired signal depending on cases such as a case in which the display element CEL is a liquid crystal display device, a case in which the display element CEL is an EL display device, a case in which the display element CEL is a FED display device. To consider the case in which the display element CEL is the liquid crystal display device as an example, the controller TCON supplies a video signal line drive circuit signal DS to a video signal line drive circuit DD and supplies a gate signal line drive circuit signal GS to a gate signal line drive circuit GD. Various voltages Vd for video signal line drive circuit which include a drive voltage for circuit per se and a plurality of gray scale reference voltages are supplied to the video signal line drive circuit DD from a power source circuit PS, while various voltages Vg for gate signal line drive circuit which include a drive voltage for the gate signal line drive circuit per se and a reference voltage which becomes the reference with respect to the gate voltage are supplied to the gate signal line drive circuit GD from the power source circuit PS. Further, as a common potential of the display element CEL, a common potential voltage Vc is supplied. A video signal is supplied to video signal lines DL from the video signal line drive circuit DD and a gate signal is supplied to gate signal lines GL from the gate signal line drive circuit GD, wherein using a switching element TFT formed on the pixel, in response to the control signal to the gate signal lines GL, a potential of the video signal line DL is supplied to a pixel electrode PX (described later). By driving the liquid crystal molecules with an electric field or a voltage difference between the pixel electrode PX and the common potential Vc, the state of the liquid crystal layer is changed so as to realize the image display.
<Display Element>
<<Example of Arrangement of Group of Pixels>>
One example of a group of pixels of the display element CEL is shown in FIG. 1. The video signal of the video signal line DL is supplied to the pixel electrode PX by way of the switching element TFT which is controlled by the gate signal lines GL. The common potential is supplied to the common electrode CT via the common signal line CL. The electric field is generated between the pixel electrode PX and the common electrode CT and hence, the liquid crystal layer is driven whereby the display is performed.
The constitutional feature of the constitution shown in FIG. 1 lies in that the extending direction of the electrodes differs among the upper, lower, left and right pixels which are arranged close to each other. Accordingly, this embodiment is characterized in the arrangement per se that the extending direction of the electrodes differs among the upper, lower, left and right pixels. One example of the division of pixel pattern for realizing such a constitutional feature is shown in FIG. 2. Symbol UE indicates an upper electrode which constitutes an upper layer and includes a large number of line-like portions or slits. Symbol LE indicates a lower electrode which constitutes a lower layer and is formed in a planar shape. Depending on the direction of the slits, for example, of the upper electrode UE, the extending direction of the electrode can be changed and hence, the direction of the electric field can be controlled.
FIG. 2A shows a pixel pattern in which the slits extend in the right upward direction, while FIG. 2B shows a pixel pattern in which the slits extend in the right downward direction. By alternately arranging these two pixel patterns as the neighboring pixels in the upper, lower, left and right directions, it is possible to realize the constitution in which the extending direction of the electrodes differs among the upper, lower, left and right pixels. So long as the extending direction of the electrodes differs among the upper, lower, left and right pixels, any pixel structure can be used. For example, the present invention may apply to the arrangement of the direction of the slits or projections in a vertical orientation method (a VA method) display device.
FIG. 3 shows one example of color filter arrangement in the arrange of the group of pixels in FIG. 1. As the color filters, the color filters of three primary colors consisting of red (R), green (G) and blue (B) are arranged, for example. In these three primary colors, the color filters in common color are arranged in the group of pixels in the longitudinal direction. Due to such an arrangement, as can be clearly understood from FIG. 2, even when the pixels are observed in view of each monochroic unit, the extending direction of the electrodes differs among the upper, lower, left and right pixels. It is more desirable that the extending directions of the electrodes are arranged in symmetry between the neighboring pixels with respect to the extending direction of the video signal line GL or the extending direction of the gate signal line GL. Due to such a constitution, it is possible to realize the improvement of a viewing angle not only in the case of white display which performs the display using all of R, G, B but also in the case of primary color display which performs the display using only one color out of R, G, B. This implies that it is possible to realize the improvement of the viewing angle even in the display of the color other than white which is realized by combining a plurality of colors.
An advantageous effect on the improvement of the viewing angle obtained by such a constitution is explained in conjunction with FIG. 4. FIG. 4 is a view which shows the arrangement shown in FIG. 3 in an expanded manner. Symbols (A), (B) respectively correspond to, for example, the pixel (a) and the pixel (b) in FIG. 2. That is, these pixels are pixels which differ in the extending direction of the electrodes. Symbols R, G, B in the drawing indicate the correspondence with the display of the colors R, G, B.
For example, in performing the white display, the display is performed using all pixels. Accordingly, the pixels (B) are uniformly arranged outside the G(B) of the pixel (A). Accordingly, it is possible to offset the viewing angle dependency (or the directional dependency of coloring) of the pixels (A) and the viewing angle dependency of the pixels (B) and hence, the viewing angle dependency can be reduced. Particularly, when the electrode arrangement direction of the pixels (A) and the electrode arrangement direction of the pixels (B) are arranged in symmetry with respect to the gate signal line GL or the video signal line DL, it is possible to maximize the offset effect and hence, it is possible to realize the wide viewing angle which substantially eliminates the viewing angle dependency.
Next, the case in which the red (R) display is performed is considered. With respect to the pixel R(B) in the drawing, the pixels of R which are arranged closest in the upper, lower, left and right direction of the pixel R(B) are always constituted of the pixels R(A). Further, with respect to the pixel R(A) in the drawing, the pixels of R which are arranged closest in the upper, lower, left and right direction of the pixel R(A) are always constituted of the pixels R(B). That is, it becomes apparent that since only the pixels of R are used in the monochroic display of red, it is possible to improve the viewing angle also in the monochroic display of red in the same manner as the white display. In the same manner, the improvement of the viewing angle is realized also in the monochroic display of B meaning blue and in the monochroic display of G meaning green.
Further, since the colors other than the monochroic colors can be displayed as the combinations of R, G, B, it is possible to realize the improvement of viewing angle in the display of these colors. That is, it is possible to achieve the remarkable advantageous effect that the display device having the wide viewing angle can be realized irrespective of the kinds of colors.
Such a wide viewing angle is particularly preferable in the display device applicable to a large-sized TV set. Further, in the large-sized TV set which has been developed for digital broadcasting, an aspect ratio (for example, 16:9) of a screen is larger than an aspect ratio (4:3) of a conventional NTSC type TV set and hence, it is possible to ensure a large perspective angle from a viewer at the center and corner portions of a screen. Accordingly, this technique is extremely effective for realizing the enlargement of the viewing angle due to the arrangement of the group of pixels set forth in the concept of the present invention.
Further, compared to a case in which a plurality of electrode directions are provided in the inside of the single pixel, it is possible to unify the arrangement direction of electrodes in the inside of one pixel and hence, invalid regions and domain generating regions can be reduced whereby the enhancement of numerical aperture can be realized and, at the same time, the enhancement of brightness and the reduction of power consumption of the display device as a whole can be realized. Further, since a pattern in the inside of the pixel can be simplified, for example, the flow of an etching solution in performing the wet etching of fine line-like or slit-like electrodes in the inside of the pixel is unified whereby defects on etching such as the formation of residues or the disconnection can be reduced thus capable of enhancing a yield rate.
<<Arrangement Example of Polarization Transmission Axis and Initial Orientation Direction>>
When the above-mentioned liquid crystal display element is used as the display element CEL, to eventually convert the modulation of light by the liquid crystal layer to a visible state, in the transmissive-type liquid crystal display element, for example, the liquid crystal layer is arranged between two polarizers. In the liquid crystal layer, the orientation of the liquid crystal is changed by the electric field generated by the above-mentioned electrodes, for example. In a state that the voltage is not applied to the liquid crystal molecules of the liquid crystal layer, as an example, the treatment which aligns the liquid crystal molecules in one direction is performed. This treatment is called as the initial orientation treatment and the initial orientation direction ORI is set by the orientation treatment which applies rubbing to the orientation film or irradiates polarization ultraviolet rays to the orientation film.
One example of the relationship between the polarization transmission axis of the polarizer and the initial orientation direction in the pixel having the line-like or slit-like pattern shown in FIG. 2 is shown in FIG. 8A and FIG. 8B. Symbol GL indicates the extending direction of the gate line, symbols PL 1 , PL 2 indicate polarization transmission axes of one and another polarizers and these polarization transmission axes PL 1 , PL 2 are arranged to be orthogonal from each other. The initial orientation direction ORI is arranged as shown in FIG. 8A when the liquid crystal molecules have the positive dielectric anisotropy and is arranged as shown in FIG. 8B when the liquid crystal molecules have the negative dielectric anisotropy. Accordingly, when the electric field is generated between the pixel electrode PX and the common electrode CT, it is possible to make the direction of rotation of the liquid crystal molecules opposite from each other between the pixel shown in FIG. 2A and the pixel shown in FIG. 2B whereby it is possible to constitute the display element CEL having the wide viewing angle irrespective of the color displayed when the above-mentioned arrangement is combined with the arrangement shown in any one of FIG. 1 and FIG. 3 to FIG. 7. Further, in a display mode in which the initial orientation direction becomes substantially perpendicular to the substrate, that is, in a so-called vertical orientation method, the initial orientation direction ORI becomes the perpendicular direction. In this case, the arrangement is configured such that the directions that the liquid crystal molecules are inclined assume a plurality of directions when the voltage is applied to the liquid crystal. However, also in this case, it is desirable that two polarizers are arranged to become orthogonal from each other to realize the high contrast and the wide viewing angle.
<<Supply Example of Common Voltage to Group of Pixels>>
In supplying the common voltage to the group of pixels, as shown in FIG. 1 as one example, it is possible to supply the common voltage to the group of pixels which extend in the lateral direction, for example, using the common signal line CL. However, as can be clearly understood from FIG. 1, the common signal lines CL are spaced apart from each other. By making the common potential more stable, it is possible to make the display quality stable. Further, it is also possible to reduce a line width of the common signal line CL thus realizing the further enhancement of the numerical aperture.
FIG. 5 shows an example in which the common electrodes CT of the pixels which are arranged close to each other in the vertical direction are electrically connected with each other using a bridge line BR. Since the common electrodes CT of the respective pixels are connected to the common signal line CL, the common potential is supplied to the respective pixels from the upper, lower, left and right directions in a matrix array whereby the common potential can be largely stabilized.
FIG. 6A shows an example in which each bridge line BR is provided for a plurality of pixels. In the drawing, one bridge line BR is allocated to three pixels. The common potential stabilization effect obtained by the bridge line BR has the feature that the brightness irregularities between the neighboring rows can be eliminated compared to the case which has no bridge line. This feature can be achieved by electrically connecting the neighboring common signal lines CL which extend in parallel. Since the connection distance is short and the frequency is large, it is unnecessary to make the bridge line BR have the low resistance comparable to the resistance of the common signal line CL. Accordingly, even when the bridge lines BR are arranged in a state that one bridge line BR is allocated to the plurality of pixels, it is possible to obtain the advantageous effect.
By arranging the bridge line BR in a state that one bridge line BR is allocated to the plurality of pixels, there exist the pixels which have no bridge line BR and, in these pixels, a space over the gate signal line GL becomes wider than the pixel having the bridge line BR. Accordingly, it is preferable to form the pixels as shown in FIG. 6B where support columns SOC or the like which hold the distance between two substrates of the display element CEL are arranged in the pixels.
FIG. 7 shows an example in which the pixels on which the bridge line BR is arranged are not aligned in a straight line in the longitudinal direction. Since the bridge line BR is arranged close to the video signal line DL, a parasitic capacitance is generated between the bridge line BR and the video signal line DL. When the bridge lines BR are uniformly provided to all pixels, the generation of the parasitic capacitance also becomes uniform and hence, there is no influence of the parasitic capacitance to the image quality. However, when the bridge lines BR are provided only to the group of pixels which extend in the particular longitudinal direction, the parasitic capacitance is generated only on the group of pixels and hence, there arises the difference in the parasitic capacitances of video signal lines DL. Although it is possible to design the bridge lines BR such that no influence of a level which causes a drawback in view of image quality is generated, it is needless to say that it is desirable to eliminate such a possibility in principle. Accordingly, by arranging the bridge lines BR as shown in FIG. 7, the generation of the parasitic capacitance is diffused so as to eliminate the possibility of the influence to the image quality.
<<Detailed Example of Pixel>>
FIG. 9 shows one example of the detailed structure of the pixel which is preferably used in the display element CEL. Hereinafter, a large number of features which this pixel possesses are explained sequentially.
<<TFT Portion>>
Features of the TFT portion shown in FIG. 9 are explained. The video signal line DL is connected with the drain electrode D of the switching element TFT. The drain electrode D is formed in a shape which surrounds the source electrode S in a semicircular manner. Further, there is provided a semiconductor layer a-Si which has an end portion thereof arranged further outside the drain electrode D and is formed in a semicircular shape. By controlling the turning ON/OFF of the semiconductor layer a-Si by the gate signal line GL, the conduction/interruption between the drain electrode D and the source electrode S can be controlled. By forming the drain electrode D in a semicircular shape which surrounds the source electrode S, it is possible to increase a channel width thus improving the writing characteristics of the TFT. Further, by also forming a distal end portion of the source electrode S into a semicircular shape, it is possible to prevent the channel length from becoming non-uniform and, at the same time, it is possible to prevent the deterioration of the reliability attributed to the concentration of electric field.
The video signal line DL is connected with the drain electrode D using a connecting member which is integrally formed with the drain electrode D. In connecting the video signal line DL, the connecting member has a large width at a connecting portion thereof with the video signal line DL and a narrow width at a connecting portion thereof with the drain electrode D. Further, a hole is formed in the gate signal line GL in the vicinity of the connecting portion and the video signal line DL is configured not to be overlapped with the gate signal line GL in the vicinity of the connecting portion. Due to such a constitution, it is possible to achieve the prevention of the disconnection of the connecting portion and the reduction of the crossing capacitance whereby the parasitic capacitance of the video signal line DL can be reduced. Further, since the connecting member gets over the gate signal line GL with an angle, that is, since the connecting member gets over the gate signal line GL in a non-perpendicular manner, the possibility of disconnection can be reduced.
<<<Pixel Electrode Connecting Portion>>>
The source electrode S of the switching element TFT in the pixel shown in FIG. 9 once gets over the gate signal line GL and extends and, thereafter, is bent in the direction parallel to the gate signal line GL and, subsequently, is bent and extends in the direction of the gate signal line GL and forms a connecting region. The gate signal line GL is formed in a state that the gate signal line GL is recessed in the connecting region portion, that is, in a state that a line width thereof is narrowed thus ensuring the connecting region. The source electrode S and the pixel electrode PX are electrically connected with each other via a through hole TH 1 formed in the connecting region. The reason that the connecting region is arranged in a state that the connecting region intrudes toward the gate signal line GL side is to ensure the numerical aperture. Further, the resistance of the line becomes dominant at a narrowest portion of the line. In the constitution shown in FIG. 9, the gate signal line GL has a hole at an intersecting portion thereof with the video signal line DL and is formed into two portions which have a narrow line width and these two portions are merged again to form the bold line. This branching of the gate signal line GL into two portions is, when the short-circuiting is generated between the gate signal line GL and the video signal line DL, to enable the correction of the short-circuiting by separating the branched portion where the short-circuiting is generated. Since the total line width of the gate signal line GL is narrow at this portion, with respect to the resistance of the gate signal line GL, the value becomes dominant at the portion having this width. Accordingly, by forming the connecting portion with the pixel electrode PX in a state that the connecting portion intrudes toward the gate signal line GL side, the enhancement of numeral aperture is realized and, at the same time, the substantial increase of the resistance value of the gate signal line GL attributed to the intrusion of the connecting portion can be restricted to a trivial value. Further, the gate signal line GL is configured to have a large width at the portion where the TFT is formed than the portion where the gate signal line GL crosses the video signal line DL or the vicinity of the connecting portion with the pixel electrode PX. Accordingly, it is possible to ensure the large channel width of the TFT and hence, the display device which exhibits the high yield rate and the high image quality can be realized.
<<<Common Signal Line and Common Electrode>>>
In the pixel shown in FIG. 9, the common signal line CL extends in parallel with the gate signal line GL. The common signal line CL is formed of a metal material on the same layer as the gate signal line GL as an example. The common signal line CL is connected with the common electrode CT. Here, in the application of the present invention to a reflective-type display device, for example, the common electrode CT may be formed integrally with the common signal line CL using the same material. However, when the common electrode CT adopts the planar constitution as shown in FIG. 9, to use the display element CEL in the transmission display, it is necessary to use the common electrode CT formed of a transparent electrode. Accordingly, the electrical connection between the common electrode CT and the common signal line CL is constituted as the connection of different layers. Since the common electrode CT and the common signal line CL constitute the different layers, in performing the connection, there arises a phenomenon that one layer gets over another layer and a disconnection may occur at the get-over portion. Accordingly, the prevention of such a disconnection becomes important for ensuring a yield rate.
FIG. 12A and FIG. 12B show an example of a case in which the common signal line CL is formed above the common electrode CT and the common signal line CL directly gets over the common electrode CT. In the constitution shown in FIG. 12B, when the common signal line CL gets over the common electrode CT, the get-over portions OH are formed on both sides of the common electrode CT. These get-over portions OH are extremely thin having the same width with the common signal line CL as can be understood from the drawing. When the disconnection occurs also on either one of these get-over portions OH, the common electrode CT cause a line defect. Accordingly, this example provides the structure which largely influences the yield rate.
FIG. 12A shows the improved structure, wherein end portions or end sides of the common electrode CT are arranged to fall within the width of the common signal line CL. In other words, the common electrode CT is arranged such that the end portions thereof are arrange to be positioned in the midst of the common signal line CL in the widthwise direction. Accordingly, it is possible to ensure a region where the common signal line CL extends without being overlapped to the common electrode CT and hence, it is possible to set the possibility of occurrence of complete disconnection at an extremely low level. Further, it is possible to prolong an extension length of the end sides of the common electrode CT on the common signal line CL and hence, even when the disconnection occurs by a chance, it is possible to supply the common potential to the common electrode CT from the common signal line CL through other portion. Accordingly, it is possible to ensure the highly reliable connection having redundancy and hence, the high-quality display device can be realized with a high yield rate.
<<<Connection of Common Potential of Upper and Lower Pixels>>>
By electrically connecting the common potentials of the neighboring upper and lower pixels, the common potentials are made stable. In FIG. 9, the electrical connection is established using the bridge line BR.
In FIG. 9, the common signal line CL includes a projecting portion or a large-width portion at a portion thereof. This portion constitutes a common potential connecting portion CC of upper and lower pixels to which the common potential is supplied from the common signal line CL. The bridge line BR is connected to the common potential connecting portion CC via a through hole TH 2 . The bridge line BR is arranged over the gate signal line GL in a spaced-apart manner by way of at least the gate insulation film GI, traverses the gate signal line GL and extends to another neighboring pixel. In another pixels which are arranged close to the pixel in the vertical direction, a different island-like common potential connecting portion CC is formed. The common potential connecting portion CC is formed of the same metal as the common signal line CL, for example, and has at least a portion thereof overlapped to the common electrode CT. The bridge line BR is connected with this island-like common potential connecting portion CC by way of the through hole TH 2 . Accordingly, it is possible to establish the electric connection of the common potentials of the neighboring pixels in the vertical direction.
The different island-like common potential connecting portion CC may, in the structure which forms the common signal line CL on the portion, be integrally formed with the common signal line CL. However, by supplying the matrix-like common potentials using the bride line BR, a demand for the line resistance of the common signal line CL is reduced and hence, by forming the common signal line CL only on one end side of the pixel, it is possible to increase the numerical aperture correspondingly.
Further, even when the bridge line BR is directly connected to the common electrode CT without through the common potential connecting portion CC, it is possible to achieve the matrix power supply with respect to the electrical connection. However, to take the yield rate and the image quality into consideration, it is more preferable to establish the electric connection via the common potential connecting portion CC.
That is, since the connection is performed via the through hole, a layer thickness of the liquid crystal layer differs in the vicinity of the through hole and hence, there may be formed a region where leaking of light occurs due to a reason that the orientation treatment is not performed sufficiently whereby the image quality is liable to be easily lowered. Accordingly, by forming the common potential connecting portion CC using a metal material which generally possesses the light blocking property, it is possible to achieve the light blocking of the through hole portion. It is needless to say that, in the reflective-type structure or the like in which the common electrode CT is made of a metal material, the common electrode CT also serves as the common potential connecting portion CC.
Further, the connection at the common potential connecting portion CC is established by connecting the bridge line BR to the through hole. That is, the bridge line BR is patterned by etching. When the display device is normally manufactured, the material and the connection structure of the bridge line BR and the common electrode CT do not influence the yield rate. However, in performing the patterning by exposing the bridge line BR, there exists a step in which a photo resist is formed in a same shape as the bridge line BR, the etching is performed using the photo resist as a mask, and an extra portion around the bridge line BR is removed. Since the bridge line BR is formed as an isolated thin pattern, the bridge line BR is formed in a pattern with which the photo resist which constitutes a mask during etching is extremely easily peeled off. Further, when the photo resist is peeled off, the bridge line BR of the through hole portion is removed by etching and, at the same time, the lines and the electrodes arranged below the through hole portion are directly exposed to the etching. Here, assuming that the lines or pattern below the through hole portion are made of the same material as the bridge line BR, the pattern below the through hole portion are etched. When the bridge line BR is made of the same material such as ITO, SnO or the like as the transparent electrode or the common potential connecting portion CC as an example, the transparent electrode of the common potential connecting portion CC is remarkably etched in the horizontal direction thus arising the possibility that a defect occurs in an image display region in the inside of the pixel. Assuming that the common signal line CL is also made of the same material, this defect may lead to the disconnection of the common signal line CL. This becomes a cause of lowering the yield rate. Accordingly, by providing the common potential connecting portion CC which is made of the material different from the material of the bridge line BR, even when a defect occurs by a chance during the step for forming the bridge line BR, it is possible to obviate the occurrence of the display defect of the pixel. This is because that when the defect occurs only on the bridge line BR, so long as one connection is allocated to the plurality of pixels, it is still possible to maintain the bridge connection effect and hence, it is possible to obtain only the image quality improvement effect attributed to the bridge line BR.
Further, by arranging the common electrode CT such that the common electrode CT is brought into contact with the lower portion of the common potential connecting portion CC, even when the common electrode CT and the bridge line BR are made of the same type of material, it is possible to provide a protective region at the time of etching using the common potential connecting portion CC made of different material in a wide range whereby the possibility of deteriorating the yield rate can be fundamentally eliminated.
Further, the bridge line BR traverses the gate signal line GL and hence, the bridge line BR forms the parasitic capacitance with gate signal line GL. To reduce this parasitic capacitance, it is desirable to use a conductive layer remotest from the gate signal line GL as the bridge line BR.
In total, it is desirable that the bridge line BR is formed of the transparent electrode made of a material such as ITO, SnO, ITZO, IZO, ZnO or the like formed on the protective film PAS and the common potential connecting portion CC is made of the same metal material as the common signal line CL.
Further, in the example shown in FIG. 9, the common electrode CT is constituted of a planar electrode and is formed of a transparent electrode made of a material such as ITO, SnO, ITZO, IZO, ZnO or the like. Accordingly, it is desirable that the common electrode CT is connected to the common potential connecting portion CC from below the common potential connecting portion CC. Here, when both of the common electrode CT and the bridge line BR are formed of the transparent electrode, it is preferable to use the same transparent electrode material such as ITO, for example, from a viewpoint of the common use of a film forming device and an etching device in the manufacturing steps.
Further, in the constitution shown in FIG. 9, the pixel electrode PX is positioned above the common electrode CT and includes a large number of fine line-like-like portions or slit-like portions. When the display element is used as the element for transmissive display, it is also preferable that the pixel electrode PX is also formed of the same transparent electrode material. By forming the pixel electrode PX on the same layer as the bridge line BR, it is possible to obviate the increase of the number of layers of the layer structure and hence, the number of steps can be obviated.
In FIG. 9, one end of the pixel electrode PX is arranged to be overlapped to the common potential connecting portion CC. In the common potential connecting portion CC, the bridge line BR to which the common potential is applied is formed on the same layer as the pixel electrode PX and constitutes a singular point in the display device which performs the display using the electric field generated between the potential of the pixel electrode PX and the common potential. Since the direction of the electric field differs from the originally intended direction, this becomes a cause of the deterioration of the image quality. Accordingly, by overlapping this region on the common potential connecting portion CC having the light blocking property, the influence is eliminated. Further, for that end, a shape of an end side of the common potential connecting portion CC and a shape of an end side of the pixel electrode PX have the similar shapes in a region where the common potential connecting portion CC and the pixel electrode PX are overlapped to each other.
Here, the common potential connecting portion CC is formed in a shape where the pixel-electrode-PX-side corner portions thereof are cut. This provision is made to eliminate the undesired light blocking region thus enhancing the numerical aperture. In this case, as shown in FIG. 9, the pixel electrode PX and the common potential connecting portion CC are configured to be overlapped to each other at three sides which are unparallel to each other and the pixel electrode PX and the common potential connecting portion CC, that is, the light blocking layers extend in parallel.
Here, by forming the vicinity of the connecting portion of the bridge line BR in the same manner, it is possible to minimize the required light blocking region.
In this region, the distance between the pixel electrode PX and the bridge line BR as viewed in parallel is set longer than the distance between the bridge line BR and the common electrode CT as viewed in parallel. This provision is made to obviate the short-circuiting attributed to the constitution that the pixel electrode PX and the bridge line BR are formed on the same layer and, at the same time, to sufficiently ensure the contact surface area between the common electrode CT and the common potential connecting portion CC.
<<<Arrangement of Group of Pixels>>>
The pixel electrode PX shown in FIG. 9 is configured such that a large number of slits extend in one direction and the direction differs among the pixels which are arranged close to each other in the upper, lower, left and right directions. Due to such a constitution, it is possible to enlarge the viewing angle irrespective of the kind of color. Here, this arrangement of the group of pixels relates to the viewing angle enlarging effect and even with respect to a case in which a plurality of directions exist in the inside of one pixel or a case in which the same direction is given in all pixels, these cases can obtain other advantageous effects attributed to other disclosed constitutions.
Further, the color filters CF are, as an example, are arranged such that, as shown in FIG. 3, wherein the color filters CF are common in the longitudinal direction and the color filters of colors R, G, B are arranged in the lateral direction. In arranging the color filters CF, it is desirable to form the black matrix BM as a partition between the color filters CF and a light blocking layer for enhancing a contrast ratio due to the light shielding of undesired regions. FIG. 10 shows an example of a case in which a black matrix BM is formed with respect to a pattern shown in FIG. 9. The black matrix BM is formed in principle such that the end portions of the black matrix BM falls within the inside of the region where the pixel electrode PX is formed. However, since the common potential connecting portion CC functions as a light blocking layer in the portion of the common potential connecting portion CC, it may be possible to form a boundary in a region which exceeds the pixel electrode PX.
<<<Cross-Sectional Structure>>>
The cross-sectional structure of an essential part of the pixel shown in FIG. 9 or FIG. 10 is sequentially explained.
FIG. 11 shows the cross-sectional structure of a A-A′ portion shown in FIG. 9 or FIG. 10. On the first substrate SUB 1 , the common electrode CT is formed as the lowermost layer. As an example, the common electrode CT is formed of a transparent electrode, for example, made of ITO. The gate signal line GL and the common signal line CL are made of metal. The gate signal line GL extends between the regions where the common electrode CT is formed. The common signal line CL has a portion thereof formed in a state that the portion gets over the common electrode CT and supplies the common potential to the common electrode CT. Further, since common signal line CL is arranged such that the whole thereof does not get over the common electrode CT, the disconnection of the common signal line CL is obviated. The gate insulation film GI is formed in a state that the gate insulation film GI covers the common electrode CT, the common signal line CL and the gate signal line GL. On the gate insulation film GI, a metal layer S which is extended from the source electrode S of the switching element TFT is arranged and this extended portion constitutes a connecting portion with the pixel electrode PX. For this end, the gate signal line GL on the A-A′ cross section has a small line width. The protective film PAS is formed on the source electrode S. The pixel electrode PX is formed of the transparent electrode, for example, ITO in the same manner as the common electrode and is arranged on the protective film PAS. The pixel electrode PX and the source electrode S are connected with each other via the through hole TH 1 formed in the protective film PAS, while the video signal which is supplied from the video signal line DL is supplied to the pixel electrode PX through the switching element TFT. The orientation film AL is formed on the pixel electrode PX and the initial orientation treatment is applied to the orientation film AL on demand. On a back surface of the substrate SUB 1 , the first polarizer PL 1 is formed.
The second substrate SUB 2 is arranged to face the first substrate SUB 1 in an opposed manner. Black matrixes BM which block the undesired leaking of light are formed on the second substrate SUB 2 . Color filters CF are formed in a state that end portions thereof are overlapped to the black matrixes BM. Although two color filters CF are shown in a spaced apart manner in the drawing, since the color of the color filters CF in the A-A′ cross-sectional direction is equal, the color filters CF may be integrally formed. The overcoat film OC is formed in a state that the overcoat film OC covers the color filters CF and the black matrixes BM. An orientation film AL is formed on the overcoat film OC. On a back surface side of the second substrate SUB 2 , the second polarizer PL 2 is formed. A conductive layer such as ITO may be formed between the second substrate SUB 2 and the second polarizer PL 2 on demand. This is because that such a constitution brings about an advantageous effect of blocking a leaked electric field and of reducing EMI. Further, it is also possible to prevent the undesired static electricity from influencing the display of the liquid crystal layer.
The liquid crystal layer LC is formed between the substrate SUB 1 and the substrate SUB 2 . An electric field is generated by applying a voltage difference between the pixel electrode PX and the common electrode CT and the orientation of the liquid crystal molecules of the liquid crystal layer LC is changed from the initial orientation direction by the electric field thus controlling the visible display image.
The initial orientation direction ORI imparted by the orientation films AL of the substrate SUB 1 and the substrate SUB 2 is parallel to the substrate SUB 1 and the substrate SUB 2 , wherein the relationship which the initial orientation direction ORI makes with the polarization transmission axes of the polarizers PL 1 , PL 2 assumes the relationship which is explained in conjunction with FIG. 8 as one example. Due to such a constitution, it is possible to realize the normally black characteristics in which the display exhibits black when the voltage is not applied and the brightness is increased along with the applying of the voltage.
FIG. 13 is the cross-sectional structure taken along a line B-B′ in FIG. 9 or FIG. 10. On the protective film PAS, the bridge line BR which is formed of the transparent electrode, for example, ITO is formed on the same layer as the pixel electrode PX. The bridge line BR electrically connects the common electrodes CT of the pixels arranged close to each other in the upper and lower directions. The pixel which corresponds to the lower pixel shown in FIG. 9 or FIG. 10 corresponds to the left-side pixel region in FIG. 13. The common potential connecting portion CC in the region is overlapped to the common electrode CT from above the common electrode CT and is electrically connected with the common electrode CT. The common potential connecting portion CC is formed of the same metal layer as the gate signal line GL. The common potential connecting portion CC is connected with the bridge line BR via the through hole TH 2 . Here, the bridge line BR and the common electrode CT are not directly connected with each other and the common potential connecting portion CC made of the metal material is interposed between them thus realizing the enhancement of the above-mentioned yield rate. The bridge line BR traverses the gate signal line GL by way of the gate insulation film GI and the protective film PAS. By making these traversing lines spaced apart from each other as much as possible, it is possible to suppress the parasitic capacitance. The bridge line BR which traverses the gate signal line GL is connected with another common potential connecting portion CC via the through hole TH 3 . The common potential connecting portion CC is integrally formed with the common signal line CL. Further, by connecting the common electrode CT as the lower layer, the electric connection between the pixels is established.
FIG. 14 is the cross-sectional structure taken along a line C-C′ in FIG. 9 or FIG. 10. This drawing particularly relates to the explanation of the structure of the switching element TFT portion. In the region, the blocking of light of the switching element TFT is necessary and hence, the black matrixes BM which constitute the light blocking layer are formed over the whole region of the substrate SUB 2 . The gate signal lines GL formed on the substrate SUB 1 are, since hole portions are formed in the gate signal lines GL to perform the above-mentioned correction, arranged in a spaced apart manner in FIG. 14. Although the video signal line DL extends in the hole portion, to reduce the possibility of disconnection of the video signal line DL at the time of getting over the gate signal line GL before and after the hole portion, the semiconductor layer a-Si is formed below the video signal line DL. The connecting portion extends toward the gate signal line GL from the video signal line DL and is connected to the drain electrode D of the switching element TFT. The source electrode S is sandwiched by the drain electrodes D from both sides and the semiconductor layer a-Si is formed between these two drain electrodes D thus forming the channel region of the switching element TFT. Here, usually, a high-concentration doped layer n + is formed on an upper surface of the semiconductor layer, wherein the high-concentration doped layer n + remains between the drain electrode D, the source electrode S and the semiconductor layer a-Si and is removed in the channel region between the drain electrode D and the source electrode S thus enhancing the characteristics of the switching element TFT. However, the constitution is omitted from the drawing.
FIG. 15 is the cross-sectional structure taken along a line D-D′ in FIG. 9 or FIG. 10. The black matrix BM is arranged between the pixels which are arranged close to each other in the lateral direction thus interrupting the undesired leaking of light. The color filters CF which are arranged close to each other in the lateral direction differ in color from each other and hence, the color filters CF exhibit the different colors from each other. In each pixel, the common electrode CT is formed in a planar shape and is formed of the transparent electrode such as ITO, for example, in case of the transmissive-type display element. When the common electrode CT is used for the reflective-type display element, the metal layer is used as the common electrode CT. The pixel electrode PX is formed on the protective film PAS and is formed of the transparent electrode such as ITO, for example, in case of the display element for transmissive display. Since the pixel electrode PX is directly formed below the orientation film, even in the display element CEL for reflective-type display, the pixel electrode PX is preferably made of the transparent electrode from a viewpoint of enhancing the reliability.
The pixel electrode PX includes a large number of line-like portions, wherein portions between the line-like portions form regions which expose the common electrode CT between the pixel electrodes PX. Accordingly, a route which terminates the electric field from the pixel electrode PX at the common electrode CT is formed and, by driving the liquid crystal molecules of the liquid crystal layer LC by the electric field, the image display can be achieved. When both of the pixel electrode PX and the common electrode CT are formed of the transparent electrode for transmissive display, the substantially whole display region becomes transparent and hence, it is possible to realize the highly bright display device which exhibits the high optical transmissivity.
Further, since the directions of the electrodes can be controlled by the directions of the line-like portions or the slit portions formed in the upper electrodes such as the pixel electrodes PX, even when the gate signal lines GL and the video signal lines DL are arranged orthogonally, it is possible to freely set the directions of the electrodes without hardly influencing the numerical aperture.
<<Another Example of Detailed Example of Pixel>>
In FIG. 9, one example of the detailed structure of the pixel which is preferably applicable to the display element CEL is shown. The constitution and the advantageous effects explained in <<<TFT portion>>>, the constitution and the advantageous effects explained in <<<pixel electrode connecting portion>>>, the constitution and the advantageous effects explained in <<<common signal line and common electrode>>>, and the constitution and the advantageous effects explained in <<<Connection of common potentials of upper and lower pixels>>> can be obtained by pixels having other various planar constitutions. One example of these pixels is explained.
FIG. 62 is a view which corresponds to FIG. 9 and shows the planar constitution of the pixel. The largest point which makes the constitution shown in FIG. 62 different from the constitution shown in FIG. 9 lies in that the arrangement of slits formed in the pixel electrode PX is common with respect to respective pixels. In FIG. 62, the direction of the slits in the pixel electrodes PX differs between an upper region of the pixel and a lower region of the pixel. That is, the slits are arranged downwardly as the slits extend toward one side surface of the pixel in the upper region, while the slits are arranged upwardly as the slits extend toward one side surface of the pixel in the lower region. That is, the slits are arranged in the direction that the slits are converged to the center of the pixel. Due to such a constitution, the correction of the viewing angle can be performed in the inside of one pixel.
Different from the constitution shown in FIG. 9, in the constitution shown in FIG. 62, there exist regions where the directions of the slits differs, that is, the upper region and the lower region in the inside of one pixel and hence, the use efficiency of the pixel is lowered at the center region which constitutes a boundary between two regions. Accordingly, the numerical aperture is slightly reduced. However, in the display device which is used as a screen of a PC monitor or the Internet, there may be a case that the constitution shown in FIG. 62 which always realizes the correction of the viewing angle with respect to any images is suitable. It is possible to select either one of the above-mentioned constitution shown in FIG. 62 and the constitution which maximizes the brightness in FIG. 9 and is particularly suitable for display of natural scene such as the TV set depending on the usage or application and there may be a case that the constitution shown in FIG. 62 is suitable. In this case, in the image of the PC monitor or the Internet, there is no continuity in the information which is observed in the natural scene between the pixels and hence, the importance of the necessity of stability of the common potential between the pixels is further increased compared to the case of the constitution shown in FIG. 9. Even in such a case, in the constitution where the direction of the slits formed in the pixel electrode PX differs between the upper region and the lower region of the pixel, by providing the bridge line BR so as to connect the common electrodes CT between the upper and lower neighboring pixels, it is possible to make the common potential stable thus realizing the stable image display.
Further, when the bridge line BR is formed in the constitution where the direction of the slits formed in the pixel electrodes PX differs between the upper region and the lower region of the pixel PX, the manner of arranging the bridge line BR gives the different influence to the numerical aperture. In FIG. 62, to enhance the numerical aperture, the bridge line BR is formed on a side where the slits are converged. Further, the common potential connecting portions CC are provided respectively corresponding to upper and lower end portions of the side where the slits are converged. Due to such a constitution, it is possible to enhance the numerical aperture compared to the case in which the common potential connecting portions CC are formed on the side where the slits are diffused.
Further, in the constitution shown in FIG. 62, as an example, in the center region of the pixel electrode PX, a pattern in which the pixel electrode PX repeats the expansion and the contraction of a width thereof at least three times is formed. Due to such a constitution, it is possible to provide the constitution whose boundary between the upper region and the lower region of the pixel electrode PX can be hardly observed with eyes and hence it is possible to enhance the integrity of the pixel. Further, in the center region of the pixel electrode PX, the pattern in which the pixel electrode PX repeats the expansion and the contraction of the width at least three times is suitable for avoiding the rapid change of the potential of the pixel electrode PX. This constitution is particularly effective in the display image or the display method which requires the transitional characteristics of display, for example, a case in which the black image is written in the screen periodically.
FIG. 63 is a view which corresponds to FIG. 10 and shows one example of the planar structure of the pixel in a state that the light blocking layer BM is formed on the constitution shown in FIG. 62.
FIG. 64 shows an example which slightly differs from the constitution shown in FIG. 62 with respect to the constitution of the center portion of the pixel.
In FIG. 64, the slits formed in the pixel electrode PX are formed such that the upward slits and the downward slits are alternately meshed with each other at the center region of the pixel. In FIG. 64, this constitution also simultaneously adopts the above-mentioned pattern in which the pixel electrode PX repeats the expansion and the contraction of a width thereof at least three times. By adopting the constitution in which the upward slits and the downward slits formed in the pixel electrodes PX are alternately meshed with each other at the center region of the pixel, it is possible to enhance the utilization efficiency of the pixel at the center region whereby the brightness can be enhanced.
<<Dummy Pixel Region>>
<<<Arrangement of Pixels at Corner Portions>>>
As shown in FIG. 16A a dummy pixel region DMY is arranged in the periphery of the display region DR of the display element CEL. This provision is made to approximate the conditions such as parasitic capacitance and the like of the pixel at an outermost periphery of the display region and other pixels as close as possible.
Here, the dummy pixel region DMY can be divided into a plurality of regions as shown in FIG. 16B. That is, the dummy pixel region DMY can be divided into an upper dummy pixel region D(D), a lower dummy pixel region L(D), a left dummy pixel region D(G) and a right dummy pixel region D(LD). By repeating a pattern which is equal to a pattern in the inside the display regions in these dummy pixels, it is possible to arrange the conditions between the dummy pixel region and the display region. Further, from a viewpoint of neutralizing the influence with respect to any display, it is possible to adopt the structure which exposes only the common potential. This is because that even with respect to the pixels used for display, at the time of performing the black display, the common potential is applied to both of the pixel electrode PX and the common electrode CT.
Here, with respect to the group of pixels on the outermost periphery of the display region which are arranged in parallel in the lateral direction, for example, with respect to the group of pixels on the outermost periphery which are arranged in parallel in D (LD) in FIG. 16B, the degree of influence from the D(DL) is substantially equal between the neighboring pixels. Further, with respect to the group of pixels on the outermost periphery of the display region which are arranged in parallel in the longitudinal direction, for example, with respect to the group of pixels on the outermost periphery which are arranged in parallel in D (G) in FIG. 16B, the degree of influence from the D(G) is substantially equal between the neighboring pixels. However, with respect to the dummy pixel C 1 at the corner portion which constitutes a position where the D (LD) and the D (G) intersect imparts the influence singularly to the pixel at the corner portion of the effective display region DR which is closest to the C 1 . Here, since the brightness change which is singularly generated at the characteristic portion such as the pixel of the corner portion may bring about the possibility that all products have the defects in common among products and hence, it is necessary to eliminate such possibility.
Accordingly, the present invention adopts the constitution which allows the directions of the electrodes of the pixels at the corner portions to hardly receive the influence from the dummy pixels at the closest corner portions.
FIG. 17 is a schematic explanatory view and schematically shows the arrangement of the electrodes of the pixel at corner portions in the inside of the effective display region DR which is closest to the dummy pixels C 1 , C 2 , C 3 , C 4 at the four corner portions of the dummy pixel region DMY. This arrangement is characterized in that the respective pixels at the corner portions of the display region adopt the electrode arrangement which hardly receives the influence of the electric field from the dummy pixels at the corner portions.
This constitution is explained more easily in conjunction with FIG. 18. FIG. 18A shows that the dummy pixels C 1 , C 2 , C 3 , C 4 are formed on the corner portions of the display region DR by taking the center of the display region DR into consideration. Here considered is a case in which in the group of pixels in the effective display region, groups of pixels having two electrode directions shown in FIG. 188B and FIG. 18C which correspond to FIG. 2A and FIG. 2B are present. Here considered is a line segment which connects C 1 and C 2 in FIG. 18A, that is, an imaginary direction of the electric field extending toward the effective display region from the dummy pixel and the influence of the electric field with the electrode shape shown in FIG. 188B and FIG. 18C using a dotted line. In case of the direction of slits shown in FIG. 18B, an acute angle θ 1 which the dotted line and the slits make is set smaller than an angle θ 2 which the dotted line and the slits make in case of the direction of slits shown in FIG. 18C. In case of the direction of slits shown in FIG. 18B, the opening portions of the slits are arranged to approach the dummy pixels and hence, the arrangement is liable to easily receive the influence of the electric field from the dummy pixel. To the contrary, In case of the direction of slits shown in FIG. 18C, the arrangement is liable to hardly receive the influence of the electric field from the dummy pixel. Accordingly, it is desirable that the pixels at the corner portions corresponding to C 1 , C 3 have the electrode pattern shown in FIG. 18C. To the contrary, the pixel shown in FIG. 18B is desirable as the pixels in the vicinity of C 2 and C 4 .
Here, as shown in FIG. 18B and FIG. 18C, the explanation has been made with respect to the case in which the lower electrode LE which constitutes the lower layer is formed in a planar shape and the upper electrode UE which constitutes the upper layer is formed in a slit shape. However, the same goes for a vertical orientation method in which only the upper electrodes UE are formed on one substrate provided that the slits are formed.
Although the relationship may be inverted depending on the voltage and the shape of the dummy pixels at the corner portions, the present invention returns to FIG. 17 and the desirable constitution is required to satisfy the following (1).
(1) The dummy pixels include the line-like electrodes or slits, wherein the direction of the line-like electrodes or slits is equal between the pixels formed on the corner portions which face in an opposed manner and at least in the vicinities of the corner portions. It is more preferable that the following (2) is satisfied in addition to the above-mentioned (1).
(2) The dummy pixels include the line-like electrodes or slits, wherein the direction of the line-like electrodes or slits differs between the pixels which are most spaced apart from each other on the same side or at least in the vicinities of the corner portions.
To define the above-mentioned arrangement in view of the object, it is safe to say that the electrode arrangement of the pixels in respective corner portions of the effective display region assumes the arrangement which suppresses the influence from the dummy pixels at the corner portions.
To define the dummy pixels with respect to the case corresponding to the explanation of FIG. 18, the definition becomes as follows (3).
(3) When two kinds of pixels which differ in the direction of the line-like electrodes or the slits are provided, it is safe to say that with respect to the direction of the linear electrodes or slits formed in the pixels at the corner portions, by comparing an acute intersecting angle which the direction of the line-like electrodes or the slits makes with respect to a line which connects the corner portion and the center of the display region, the pixels having the direction of the slits or the electrodes which intersects with an angle larger than the acute intersecting angle are arranged.
<<<Supply of Common Potential Using Dummy Pixel Region>>>
FIG. 19 is a view for explaining the supply of the common potential using the dummy pixel region in the vicinity of the corner portion and shows the region in the vicinity of the C 1 shown in FIG. 16 or FIG. 17.
Below the pixel on the display region at the lowermost side, a dummy gate line DMYG is arranged, wherein the dummy pixels are arranged such that the conditions thereof approximate the conditions of other pixels. Below the dummy gate line DMYG, the dummy pixel region, that is, the dummy pixel region which corresponds to the D(LD) in FIG. 16 or FIG. 17 extends. The structure of the dummy pixel region D (LD) is explained in conjunction with FIG. 20A which show the cross-sectional structure taken along a line A-A′ in FIG. 19.
A dummy common signal line DMYC to which the common potential is supplied on the same layer with the common signal line CL extends with a large width. Due to this constitution, a bus line for supplying the common potential of low resistance is formed. The gate insulation film GI is formed on the dummy common signal line DMYC and the video signal line DL extends on the gate insulation film GI. The protective film PAS is formed in a state that the protective film PAS covers the video signal line DL. A PAS hole HL is formed in the protective film PAS and the gate insulation film GI in a region between the video signal lines DL. An upper shield electrode US is integrally formed with the bridge line BR using a transparent electrode in a state that the upper shield electrode US covers the PAS hole HL. Due to such a constitution, in respective pixels in the dummy region, the reference potential appears on the uppermost layer and hence, the potential is made stable. Further, the common potential is supplied to the respective pixels in the longitudinal direction from the dummy common potential line DMYC which functions as the bus line of low resistance via the bridge line BR and hence, the reduction of the power supply resistance of the common potential can be achieved.
The dummy common potential line DMYC and the dummy gate signal line DMYG are connected with each other on a left side in FIG. 19 thus obviating the change of the potential of the dummy gate signal line DMYG.
Outside the group of outermost peripheral pixels in the longitudinal direction on the left end, the dummy pixel region extends along the D(G) in FIG. 16 or FIG. 17. In each dummy pixel, an end portion of the common signal line CL forms a large width portion. Further, the common potential connecting metal line CMC is arranged close to the common signal line CL and an end portion of the common potential connecting metal line CMC also has a large width. These large-width portions are arranged close to each other and are electrically connected with each other by an upper shield electrode US. The explanation is made in conjunction with FIG. 20B which is a cross-sectional view of a B-B′ line portion shown in FIG. 19. On the substrate SUB 1 , the large width portion formed on the end portion of the common signal line CL is formed below the gate insulation film GI. The large-width portion of the common potential connecting metal line CMC is formed on the gate insulation film GI in a state that the common potential connecting metal line CMC is arranged close to the common signal line CL. At these large-width portions, the PAS hole HL is formed in the gate insulation film GI and the upper shield electrode US is formed in a state that the upper shield electrode US covers the hole portion whereby the common potential connecting metal line CMC and the common signal line CL become electrically conductive with each other. Further, the upper common connecting line UC is electrically connected with the DMYC through another hole portion thus realizing the supply of the common potential to the DMYC.
The common potential connecting metal line CMC and the gate signal line GL are formed on the different layers. This is because that the common potential is supplied to the common potential connecting metal line CMC using the gate signal line GL toward the display region from the outside on the left side in FIG. 19 and hence, a large number of these lines are arranged in a closely arranged manner corresponding to the number of the pixels whereby the common potential connecting metal line CMC and the gate signal line GL are formed on the different layers by way of the gate insulation film GI for obviating the short-circuiting and the electrolytic corrosion.
Also in the vicinities of other C 3 , C 3 , C 4 , in the dummy pixel portion, the lower metal dummy electrode layer and the upper shield electrode US are connected with each other via the PAS hole HL and hence, the common potential is exposed whereby the potential of the dummy pixel region is made stable.
<<<Dummy Pattern>>>
The dummy pixel region DMY is suitable for arranging the dummy pattern for various purposes. Particularly, dummy pixel region DMY is suitable for arranging a pattern to perform a quality control. FIG. 21 is characterized by arranging a plurality of measuring dummy patterns TEG-A, TEG-B, TEG-C on the dummy pixel region DMY. These measuring dummy patterns may be scattered to different sides, or may be concentrated on one side, or may be formed respectively on a plurality of sides. The important point is that the measuring dummy patterns are arranged in the dummy pixel region which is arranged closest to the pixel.
The explanation is made with respect to a case in which the dummy pattern adopts a pattern which measures film thicknesses of the gate insulation film GI, the semiconductor layer a-Si, the protective film PAS and the like.
The insulation film and the semiconductor layer are formed by a CVD method. Accordingly, film thicknesses of the films which are formed by peripheral patterns receive the influence. The purpose of measuring the film thickness using the dummy patterns is to know the film thicknesses within the display region and, for example, to feedback the obtained information to the film forming conditions in the manufacturing steps. Accordingly, even when the dummy patterns are arranged remote from the display region and obtain the information on different film thicknesses, the information has no values. Accordingly, it is important to arrange the dummy patterns on the dummy pixel region which is arranged closest to the pixel.
FIG. 22 shows an example in which, for example, one measuring dummy pattern TEG is formed in the dummy region shown in FIG. 19. When a plurality of measuring dummy patterns TEG are arranged in the dummy region, the measuring dummy patterns TEG may be arranged on the separate dummy pixel in the dummy pixel region arranged closest to the pixel based on the same technical concept which is explained hereinafter.
In the dummy pixel where the measuring dummy pattern TEG is arranged, a size of the PAS hole HL formed in the protection film PAS is reduced. Then, on the region which is covered with the obtained protective film PAS, the measuring dummy pattern TEG is arranged.
The structure and the manner of using of the measuring dummy pattern TEG related to the measurement of various film thicknesses are explained with respect to examples of various measuring dummy patterns TEG using the cross-sectional structure taken along a line A-A′ in FIG. 22.
FIG. 23A and FIG. 23B show the cross-sectional structure taken along the line A-A′ in FIG. 22, wherein FIG. 23A shows the cross-sectional structure at the time of completion and FIG. 23B shows the cross-sectional structure at the time of measuring. The measuring dummy pattern TEG-A aims at the measurement of the film thickness of the gate insulation film GI. In a stage after the formation of the gate insulation film GI and prior to the formation of the protective film PAS, as shown in FIG. 23B, a film thickness of the gate insulation film GI is detected by an optical technique which uses light Light. Since the common signal line CL is a metal layer and hence reflects light, it is possible to know the film thickness of the gate insulation film GI which is a transparent film using an ellipsometer. In FIG. 23A which shows the cross-sectional structure in the completed form, the region of the measuring dummy pattern TEG-A is recognized as the dummy pixel having the small hole in the protective film PAS.
FIG. 24A and FIG. 24B show the cross-sectional structure taken along the line A-A′ in FIG. 22, wherein FIG. 24A shows the cross-sectional structure at the time of completion and FIG. 24B shows the cross-sectional structure at the time of measuring. The measuring dummy pattern TEG-B aims at the measurement of the total film thickness of the gate insulation film GI and the semiconductor layer a-Si. In a stage after the formation of the gate insulation film GI and the formation of the semiconductor layer a-Si and prior to the formation of the protective film PAS, as shown in FIG. 24B, the total film thickness of the gate insulation film GI and the semiconductor layer a-Si is detected by an optical technique which uses light Light. By measuring the film thickness of the gate insulation film GI alone using the technique shown in FIG. 23, it is also possible to know the film thickness of the semiconductor layer a-Si alone by the subtraction. In FIG. 24A which shows the cross-sectional structure in the completed form, the region of the measuring dummy pattern TEG-B is recognized as the dummy pixel in which the isolated a-Si pattern remains.
FIG. 25A and FIG. 25B show the cross-sectional structure taken along the line A-A′ in FIG. 22, wherein FIG. 25A shows the cross-sectional structure at the time of completion and FIG. 25B shows the cross-sectional structure at the time of measuring. The measuring dummy pattern TEG-C aims at the measurement of the film thickness of the protective film PAS. The dummy video pattern DDL constituted of the video signal lines DL is formed on the gate insulation film GI. On the dummy video pattern DDL, the protective film PAS is formed. By forming the dummy video pattern DDL using a metal layer which is formed on the same layer as the video signal line DL, it is possible to optically measure the film thickness of the protective film PAS using the ellipsometer as shown in FIG. 25B.
Further, by performing the measurement after forming the upper shield electrode US using the transparent electrode as shown in FIG. 25A, it is possible to know the film thickness of the transparent electrode by subtracting the film thickness of the protective film PAS found in the step shown in FIG. 25B.
In FIG. 25A which shows the cross-sectional structure in the completed form, the region of the measuring dummy pattern TEG-C is recognized as the dummy pixel in which the pattern which is formed on the same layer as the isolated video signal line DL remains.
<Module Structure>
An example of the module structure shown as the example in FIG. 27 is explained in more detail.
<<Schematic Structure>>
FIG. 28A is a front view of the display device in a state that the upper frame UFM is mounted. The upper frame UFM is formed of a metal material. An example of a connecting portion ULC between the upper frame UFM and the lower frame LFM is formed on each side. Further, holes of positioning portions PDP are observed.
FIG. 28B, FIG. 28C, FIG. 28D and FIG. 28E are respectively views corresponding to a lower surface, an upper surface, a left surface and a right surface of the structure shown in FIG. 28A. The upper frame UFM is formed in a state that the upper frame UFM is bent and extended to side surface of respective sides thereof.
Although the upper and lower frame connecting portion ULC are not observed in FIG. 28B and FIG. 28C, portions of the frame connecting portions ULC are observed in FIG. 28D and FIG. 28E. This structure is adopted to contract a profile size of portions other than the display region of the display device. Accordingly, although the upper frame strength outside the upper and lower frame connecting portions ULC becomes weaker at a short side than a long side of the upper frame, since the distance per se of the frame is short with respect to the short side and hence, the influence on the rigidity as a whole can be suppressed. Accordingly, it is possible to achieve both of the contraction of the profile size and the maintenance of the strength.
Further, to maintain the connection strength, the larger number of the upper and lower frame connecting portions ULC are formed on the long side than the short side.
FIG. 29 is a view showing the display device as viewed from a back surface. Corresponding to the upper and lower frame connecting portions ULC when the upper and lower frame connecting portions ULC are viewed from the upper frame, the upper and lower frame connecting portions ULC are also formed on the lower frame LFM.
On the left side of the drawing, an inverter cover (high voltage side) INCH is provided and an inverter printed circuit board (high voltage side) is arranged below the inverter cover INCH. The leaking electric field from the inverter is shielded by the inverter cover (high voltage side) INCH. On the upper side of the drawing, the controller (printed circuit board) and a cover of the TCON (TCON cover) TCV are arranged. On the right side of the drawing, an inverter cover (low voltage side) INCL is provided and an inverter printed circuit board (low voltage side) is arranged below the inverter cover INCL. The leaking electric field from the low-voltage-side inverter printed circuit board is shielded by the inverter cover (low voltage side) INCL.
Both of the inverter cover (high voltage side) INCH and the TCON cover TCV are formed of metal for shielding and a large number of holes are formed in the inverter cover (high voltage side) INCH and the TCON cover TCV for heat radiation. The holes formed in the TCON cover TCV are set smaller than the holes formed in the inverter cover (high voltage side) INCH. With respect to the frequency of the leaking electric field, the frequency of the leaking electric field from the controller printed circuit board is higher than the leaking electric field from the inverter printed circuit board and hence, the heat radiation is achieved while preventing the leaking of the electric field from the holes by setting the holes formed in the TCON cover TCV small. On the other hand, although the frequency from the inverter printed circuit board is relatively small, an electric current is supplied to the light source CFL and hence, the heat generation is large. Accordingly, by forming the holes larger than the holes formed in the TCON cover TCV, it is possible to obtain both of the heat radiation and the shielding of the leaking electric field. Further, by changing the sizes of these holes, the resonance frequency of the metal shield plate can be dispersed and hence, the generation of the resonance sounds can be prevented under any operation conditions.
FIG. 30A to FIG. 30E are views for showing a state in which the respective covers consisting of the inverter cover (high voltage side) INCH, the inverter cover (low voltage side) INCL and the TCON cover TCV are removed, wherein FIG. 30A is a view as viewed from the back surface side.
On the left side of the drawing, an inverter printed circuit board (high voltage side) INPH is formed. A large number of inverter transformers are arranged on the inverter printed circuit board (high voltage side) INPH. Further, a high-voltage-side output is supplied to the light source through a connector.
On the right side of the drawing, an inverter printed circuit board (low voltage side) INPL is formed. A low-voltage-side end portion of the light source is arranged on a connector of the inverter printed circuit board (low voltage side) INPL. The inverter printed circuit board (low voltage side) INPL is divided in two and the divided inverter printed circuit boards are arranged as the inverter printed circuit board (low voltage side) INPL 1 and the inverter printed circuit board (low voltage side) INPL 2 .
The inverter printed circuit board (low voltage side) INPL and the inverter printed circuit board (high voltage side) INPH are connected with each other using an inverter printed circuit board connection cable INCC. Due to such a constitution, the low-voltage-side of the light source is connected to the connector of the inverter printed circuit board connection cable INCC via a line on the inverter printed circuit board (high voltage side) INPH using a connector and the inverter printed circuit board connection cable INCC is connected with the inverter printed circuit board (high voltage side) INPH using a connector whereby the supply of electricity to the low voltage side becomes possible.
On the lower frame LFM, inverter printed circuit board common connecting portions CCFI which allow the connection of the inverter printed circuit board to the lower frame LFM are formed. The inverter printed circuit board common connecting portions CCFI are formed on the lower frame LFM in the left-and-right symmetry. That is, even when the inverter printed circuit board (high voltage side) INPH and the inverter printed circuit board (low voltage side) INPL are arranged in a reverse manner in the left and right direction, it is possible to cope with the situation using the same display device. This implies that since the heat generation from the inverter printed circuit board is relatively large, by adjusting the arrangement relationship with other heat generating parts within a set of a liquid crystal TV set or the like, the heat generation can be made uniform whereby it is possible to prevent the generation of locally high-temperature portions.
Since the inverter printed circuit board (low voltage side) INPL can be made smaller than the inverter printed circuit board (high voltage side) INPH, an extra portion is formed at either side of the inverter printed circuit board common connecting portion CCFI. Accordingly, in the inverter printed circuit board (high voltage side) INPH, the inverter printed circuit board common connecting portion CCFI is fixed to the lower frame LFM using given portions formed on both sides of the printed circuit board. In the inverter printed circuit board (low voltage side) INPL, the inverter printed circuit board common connecting portion CCFI is fixed to the lower frame LFM using given portions formed on one side of the printed circuit board. For this end, it is desirable that a width of the inverter printed circuit board (low voltage side) INPL is ½ or less of a width of the inverter printed circuit board (high voltage side) INPH. It is more desirable that a width of the inverter printed circuit board (low voltage side) INPL is ⅓ or less of a width of the inverter printed circuit board (high voltage side) INPH. This provision is made to ensure the sufficient fixing strength by the fixing of the printed circuit board to only one side of the lower frame LFM.
On the upper side of the drawing, a controller printed circuit board is arranged. The controller TCON is formed on the controller printed circuit board. Outputs from the controller TCON are supplied to the display element CEL by a joiner (A) JNA, a joiner (B) JNB and the like via the connectors CN 1 .
FIG. 30B, FIG. 30C, FIG. 30D and FIG. 30E are respectively views corresponding to a lower surface, an upper surface, a left surface and a right surface of the structure shown in FIG. 30A. FIG. 30C shows that a printed circuit board PCB which supplies signals to the video signal drive circuit of the display element CEL is arranged on a side surface of the display device. By connecting joiner (A) JNA and a joiner (B) JNB using the connector CN 2 , various signals and voltages are supplied to the drain printed circuit board DPCB and the controller TCON. The drain printed circuit board DPCB is constituted of a drain printed circuit board DPCB 1 and a drain printed circuit board DPCB 2 . These printed circuit boards DPCB 1 , DPCB 2 are explained later.
FIG. 30D and FIG. 30E show a state that a large number of cables from the inverter printed circuit board are arranged.
FIG. 31 shows a state in which the upper frame UFM shown in FIG. 28A is removed. The intermediate frame MFM is arranged and the display element CEL is stacked on the intermediate frame MFM. On an upper side of the display element CEL, the video signal drive circuit is formed using the tape carrier TCP as an example. The video signal drive circuit is connected with either one of the drain printed circuit boards DPCB 1 , DPCB 2 . On the left side of the display element CEL, the gate printed circuit board GPCB is formed. The gate printed circuit board GPCB is connected to the display element CEL by the tape carrier TCP.
FIG. 32 is a perspective view focusing on the left upper corner portion shown in FIG. 31. A signal from the drain printed circuit board DPCB is applied to the DTCP and the video signal is applied to the display element CEL. A signal from the gate printed circuit board GPCB is applied to the GTCP and the gate signal is applied to the display element CEL. The drain printed circuit board DPCB and the gate printed circuit board GPCB are connected with each other by the joiner JNC. Due to such a constitution, compared to the case in which the gate printed circuit board GPCB is directly connected from the controller TCON, it is possible to reduce the distance of the joiner JNC and hence, the constitution which is resistant to noises can be provided.
<<Fixing of Upper and Lower Frames>>
Next, the explanation is made with respect to the upper and lower frame connecting portions ULC and positioning portions PDP. FIG. 33 is a perspective view showing an exploded state of the upper frame UFM, the intermediate frame MFM and the lower frame LFM. In the upper and lower frame connecting portions ULC, the upper frame UFM has projecting portions on a lower side thereof, the lower frame LFM has projecting portions on an upper side thereof, and hole portions are formed in the intermediate frame MFM. With respect to the positioning portions PDP, the intermediate frame MFM has projecting portions which are projected to the upper frame UFM or the lower frame LFM and hole portions are formed on the projection-side frame. This constitution is explained in more detail. The upper and lower frame connecting portions ULC which constitute an A line portion in FIG. 34 and the positioning portions PDP which constitute a B line portion in FIG. 34 in a fitting engagement state of the display device are respectively explained in conjunction with FIG. 35 and FIG. 36.
FIG. 35A is a planar schematic view of the upper and lower frame connecting portions ULC. Symbol MH indicates hole portions formed in the intermediate frame MFM and symbol SC indicates fixing screws.
FIG. 35B is a cross-sectional view taken along a line B-B′ in FIG. 35A. In the upper and lower frame connecting portions ULC, the upper frame UFM projects downwardly and the lower frame LFM projects upwardly. The holes MH are formed in the intermediate frame MFM and the upper frame UFM and the lower frame LFM are directly brought into contact with each other through the holes MH. Due to such a constitution, the upper and lower frames can ensure the direct contact with a large area with respect to the screw SC. By directly connecting the upper frame UFM and the lower frame LFM using the screw SC, the firm fixing can be realized. Further, since the upper frame UFM and the lower frame LFM are brought into direct contact with each other in a wide area around the screw SC, it is possible to ensure the further fixed connection.
FIG. 35C is a cross-sectional view taken along a C-C′ line portion in FIG. 35A and shows that the upper frame UFM projects downwardly and the lower frame LFM projects upwardly. FIG. 35D is a cross-sectional view taken along a D-D′ line portion in FIG. 35A and shows a region in a state that the upper frame UFM and the lower frame LFM are separated from each other. FIG. 35E is a cross-sectional view taken along a E-E′ line portion in FIG. 35A and shows that the upper frame UFM is arranged above the intermediate frame MFM and the lower frame LFM is arranged below the intermediate frame MFM.
FIG. 36A and FIG. 36B are explanatory views related to the positioning portions PDP, wherein FIG. 36A is a perspective plan view and FIG. 36B is a cross-sectional view taken along a line B-B′ line portion in FIG. 36A. An upper projecting portion UP is integrally formed on the intermediate frame MFM. This upper projecting portion UP can realize the positioning or the alignment of the upper frame UFM with respect to the intermediate frame MFM together with a hole UH formed in the upper frame UFM. Further, a lower projecting portion LP is integrally formed on the intermediate frame MFM. This lower projecting portion LP can realize the positioning or the alignment of the lower frame LFM with respect to the intermediate frame MFM together with a hole LH formed in the lower frame LFM.
As shown in FIG. 36A, the hole UH formed in the upper frame UFM and the hole LH formed in the lower frame LFM are formed in positions which are different in plane. This provision is provided to release an undesired force or stress which may arise at the time of connecting the upper frame UFM and the lower frame LFM by displacing the positions of the hole UH formed in the upper frame UFM and the hole LH formed in the lower frame LFM thus ensuring the firm connection of the upper frame UFM and the lower frame LFM. Further, it is also possible to obtain an advantageous effect that a resonance point is also dispersed in the upper frame UFM and the lower frame LFM so that the generation of the resonance sound can be prevented.
<<Intermediate Frame>>
The intermediate frame MFM is formed of a resin-made member. Further, as shown in FIG. 37, the intermediate frame MFM is divided into four members consisting of a right intermediate frame MFMR, a left intermediate frame MFML, an upper intermediate frame MFMT and a lower intermediate frame MFMB. These four members are formed independently from each other. Further, the respective members are individually connected to the lower frame LFM. The direct fixing of the divided intermediate frames MFM are not performed.
In the large-sized module, it is difficult to manufacture the resin members with high accuracy. Further, even when the ideal shape is ensured in an initial stage, due to the expansion and the contraction which occur due to the temperature change, the shape is displaced from a shape which is intended. This displacement of the shape applies to the display element CEL and becomes a cause of deterioration of the display quality of the display element CEL. Further, this gives rise to generation of a stress and deterioration of a vibration-resistant characteristic of the module.
Accordingly, by dividing the resin-made intermediate frame MFM in four and by preventing the divided intermediate frames from being directly fixed to each other, a size of the intermediate frame MFM per each member can be made small whereby the intermediate frame MFM which can minimize the influence of the expansion and the contraction attributed to heat can be manufactured with high accuracy. Further, the respective intermediate frames MFM are directly fixed to the metal-made lower frame LFM from the intermediate frame MFM side using the screws. Since the lower frame LFM is made of metal, the lower frame LFM can be manufactured with accuracy and receives the least change of shape attributed to the temperature change. Accordingly, it is possible to maintain the position of the intermediate frame MFM with high accuracy. In the above-mentioned upper and lower frame connecting portions ULC, by directly fixing the upper frame UFM to the lower frame LFM through the hole portion formed in the intermediate frame MFM from the upper frame UFM side using the screw, the direct firm fixing between the intermediate frame MFM and the upper frame UFM is not provided. That is, both of the intermediate frame MFM and the upper frame UFM are directly fixed to the lower frame LFM, the reference of the position can be unified to the lower frame LFM and hence, it is possible to manufacture a module having the firm structure with high accuracy. This structure is the structure which is extremely suitable for a display device having a large size such as a large-sized TV set.
Among four-split intermediate frames MFM, both of the intermediate frame MFMT and the intermediate frame MFMU extend in one direction, that is, the longitudinal direction (long-side direction) of the display device and are formed to have a relatively large length. On the other hand, the intermediate frame MFML and the intermediate frame MFMR are configured to have a shape which extends both of the lateral direction (short-side direction) and the longitudinal direction of the display device, a length of the portion in the longitudinal direction of the display device is made shorter than a length of the portion of the lateral direction. Due to such a constitution, the intermediate frame MFMT and the intermediate frame MFMB can ensure the positional accuracy in the lateral direction of the display element CEL, that is, the positional accuracy in the vertical direction of the display element CEL with high accuracy. Further, the intermediate frame MFML and the intermediate frame MFMR can ensure the positional accuracy in the longitudinal direction of the display element CEL, that is, the positional accuracy in the horizontal direction of the display element CEL with high accuracy. In this manner, by clearly separating the directions that the positional accuracy is realized for every member, it is also possible to ensure the accuracy even when the resin-made members are applied to a large-sized display device and hence, the undesired contraction of the profile size can be prevented.
Further, the intermediate frame MFML and the intermediate frame MFMR have portions thereof extended in the longitudinal direction. To enhance the positional accuracy in the vertical direction, it is desirable that the intermediate frame MFML and the intermediate frame MFMR are not brought into contact with end portions of the substrate of the display element CEL. Accordingly, it is desirable that the horizontal distance between these two intermediate frames and the end portion of the display element CEL at the same height in the vertical direction of the substrate is set longer than the horizontal distance between the intermediate frames MFMT and MFMB and the end portion of the display element CEL at the same height in the vertical direction of the substrate.
The intermediate frames MFM which are arranged close to each other have, as shown in FIG. 33, projecting portions which are displaced from each other. FIG. 38A is a view of the intermediate frames MFM in an assembled state as viewed from above. The intermediate frame MFMR and the intermediate frame MFMB have projecting portions thereof in the horizontal direction meshed with each other. Due to such a constitution, the assembly of the intermediate frame MFM is facilitated. Further, in the vicinity of the fitting portion, the intermediate frame MFMR and the intermediate frame MFML are respectively individually and directly fixed to the lower frame LFM using the screw SC. Due to such a constitution, the accuracy of end portions of the respective intermediate frames MFM can be realized. With respect to the respective intermediate frames MFM, by directly fixing the intermediate frames MFM to the lower frame LFM from the intermediate frame side at a plurality of portions using the screws S, the connection can be reinforced and, at the same time, the operability at the time of assembling the module can be enhanced by unifying the fixing with screws to the fixing from the upper side as in the case of the screw connection at the upper and lower frame connecting portions ULC. The similar shapes can be observed with respect to the fitting portion of the intermediate frame MFMB and the intermediate frame MFMR shown in FIG. 39A.
The intermediate frame MFM increases a resin thickness thereof only at portions thereof which requires the increase of the thickness and reduces the resin thickness at other portions. Due to such a provision, the intermediate frame MFM becomes light-weighted. The shape of the intermediate frame MFM can be freely set on demand by resin injection molding which uses a mold.
<<Transmission of Signals to Drain Printed Circuit Board>>
FIG. 38B is a view which is obtained by observing a lower side surface of FIG. 38A.
In FIG. 38B, a drain printed circuit board DPCB 1 is arranged. Signals from the drain printed circuit board DPCB 1 are supplied to a drive circuit (driver element) DRV on a tape carrier TCP and video signals are generated. The video signals are supplied to a video signal terminal of the display element CEL from an output terminal of the tape carrier TCP. A drive circuit may be directly mounted on the display element CEL or the drive circuit may be directly formed on the display element CEL using the TFT.
The drain printed circuit board DPCB 1 is fixed to the lower frame LFM using screws SC. At the same time, when the GND of the drain printed circuit board DPCB 1 and the lower frame LFM are electrically connected with each other by such fixing, the stable GND potential can be realized.
Two joiners are connected to the drain printed circuit board DPCB 1 from the controller printed circuit board side. The joiner (A) JNA has a large width and a small number of layers. For example, the joiner (A) JNA is constituted of a joiner having one conductive layer. The joiner (B) JNB has a narrow width and a large number of layers. For example, the joiner