This invention relates to an optical device and an apparatus employing the optical device.
(Light Emission Source)
In a conventional light emission source in which a light emitting diode is sealed in a mold resin, light emitted from the light emitting diode to its front is emitted from the light emission source as it is, but light emitted in a diagonal direction from the light emitting diode is totally reflected on a boundary surface of the mold resin and scattered in an inside wall of a housing to be lost, resulting into deterioration of use efficiency of light.
Heretofore, there has been proposed a light emission source capable of efficiently emitting the light emitted in a diagonal direction which is disclosed in the Japanese Laid-Open Patent Publication No. Hei 1-143368. FIG. 1 shows a sectional side view of a light emission source including a light emitting diode 1 , a transparent glass substrate 2 , lead frames 3 and 4 , a bonding wire 5 , a light reflecting member 6 , and a mold resin 8 made of an optically transparent resin. The lead frames 3 and 4 are disposed on a rear wall of the transparent glass substrate 2 , and the light emitting diode 1 is mounted on a rear wall of the lead frame 3 to be connected with the lead frame 4 by the bonding wire 5 . A light reflecting wall 7 of the light reflecting member 6 is formed as a polyhedron by plural monotonous surfaces.
In this conventional light emission source, light is emitted backside from the light emitting diode 1 to be reflected by the reflecting wall 7 and emitted forward through the mold resin 8 and the transparent glass substrate 2 . In particular, light emitted from the light emitting diode 1 in a diagonal direction is reflected back by the reflection wall 7 to be emitted forward through the mold resin 8 and the transparent glass substrate 2 , thereby improving the light use efficiency.
This conventional light emission source, however, has the disadvantage that light reflected by the light reflecting member is obstructed by the light emitting diode and the lead frames when it is emitted forward, thereby producing shadows of these components and deteriorating the advantage of utilization of light near the optical axis center where quantity of light should be provided most well. Furthermore, because of darkness near the optical axis center in the directional pattern of light emitted by the light emission source, its appearance is bad as a light source for a display, and its visual performance also is bad.
FIG. 2 shows a side sectional view of conventional another light emission source, wherein a light emitting diode 1 such as an LED chip is die-bonded on a leading edge of one lead frame 3 to be connected with another lead frame 4 by means of a bonding wire 5 , which is sealed in a transparent mold resin 8 . On a central part of a front wall (resin boundary surface) of the mold resin 8 , there is disposed a lens portion 9 so as to agree with an optical axis of the light emitting diode 1 .
In this conventional light emission source of FIG. 2, the light emitting diode 1 is not positioned behind the lead frame 3 , and light emitted from the light emitting diode 1 is emitted forward from the lens portion 9 without any obstruction.
In this conventional light emission source, however, only light emitted from the light emitting diode 1 to its front is used for external emission, thereby decreasing the use efficiency of light. Moreover, just one light emission source becomes so-called point light source, so that the light emission area cannot be enlarged.
(Photo Detector)
For example, a photodiode serving as a sensor is improved about its sensitivity as the light requirement is increased, and a photoelectric transducer increases an electric energy as the light requirement is increased. Accordingly, it is desirable in these photo detectors to increase the light requirement as far as possible.
In order to increase the light requirement when the intensity of incident light is the same, it is an approach to increase the light receiving area of the photo detector. However, this approach to increase the chip area of the photo detector reduces the number of chips which can be taken from one piece of monocrystal wafer, resulting into large increase of the manufacturing cost.
Moreover, it is another approach to dispose an optical lens ahead of a photo detector to condense the light striking against the lens to the photo detector. This photo detector needs a large optical lens, and the thickness is increased by the spacing between the photo detector and the lens, whereby the element becomes a large-scale.
It is, therefore, a first object of this invention to provide an optical device such as a light emission source or a light receiver provided with a desired directional pattern.
It is a second object of this invention to improve the use efficiency of the light emitted from a solid light emitter such as a light emitting diode.
It is a third object of this invention to increase a light emission area of the light emitted from a solid light emitter such as a light emitting diode.
It is a fourth object of this invention to raise the light receiving efficiency of a photo diode or a photoelectric transducer by making the light receiving area big.
It is a fifth object of this invention to raise the assembly accuracy of a light emission source and a light receiver and make the manufacturing easy.
It is a sixth object of this invention to suppress degradation of the visual performance of a light emission source or a component employing the same when it is viewed from a lower part thereof (for example, ground) by disturbance light.
A first optical device according to this invention includes an optical element, a resin boundary surface for almost totally reflecting light deviated from a predetermined front area of the optical element, and a light reflecting member, in which the optical element, the resin boundary surface and the light reflecting member are positioned so that a light path from the optical element to the external of the optical device can reflect back at least more than once with each of the resin boundary surface and the light reflecting member. The optical element is represented by a light emitter such as a light emitting diode, or a photo detector such as a photo diode or a photoelectric transducer. According to this optical device, the light deviated from the predetermined area is reflected by the resin boundary surface and the light reflecting member in the light path between the optical element and the front of the optical device, whereby a desired directional pattern may be realized by the configuration of the resin boundary surface and the light reflecting member, and the optical device may be thinned.
In a first light emission source according to this invention, a light emitter is positioned to be covered by a resin so that the light deviated from a predetermined front area in the light emitted from the light emitter is almost totally reflected by a resin boundary surface, and a light reflecting member is disposed behind the resin boundary surface so as to reflect the light emitted from the light emitter and almost totally reflected by the resin boundary surface to be emitted forward. The resin boundary surface almost totally reflecting the light may be a boundary surface between the resin and air or between the resin and other resin or a multilayer light reflecting film.
In this first light emission source, the light almost totally reflected by the resin covering the light emitter is reflected by the light reflecting member to be emitted forwardly, thereby improving the use efficiency of light. The light directly emitted forward by the light emitter can be emitted forward without any obstruction by the light emitter itself, thereby further improving the use efficiency of light and the directional pattern without darkening a center of light emission source. Moreover, the directive pattern of the light emitted from the light emission source may be optionally varied by changing the configuration of the resin boundary surface and the light reflecting member.
According to a first aspect of the first light emission source, at least a part of the resin boundary surface slants against a plane perpendicular to an optical axis of the light emitter in an area contacting with the above-mentioned predetermined area. In the light emission source of the first aspect, most of the light beams emitted from the light emitter to the boundary of the resin boundary surface and the predetermined area make angles with the optical axis smaller than the critical angles of total reflection of the light reaching the resin boundary surface. By making the angle between the light reaching the boundary of the resin boundary surface from the light emitter and the optical axis of the light emitter smaller than the critical angle of the total reflection, the light emitted from the light emitter by a smaller angle against the optical axis than the critical angle of the total reflection in the resin boundary surface is totally reflected by the resin boundary surface and further reflected forward by the light reflecting member. As a result, the ratio of stray light in the predetermined area in a front of the light emitter is reduced and the use efficiency of light is improved. All light emitted from the light emitter to the boundary of the resin boundary surface and the predetermined area is not always necessary to have an angle to the optical axis smaller than the critical angle of the total reflection of light reaching the resin boundary surface. As far as the angles of most of light beams to the optical axis are smaller than the critical angle of total reflection of light reaching the resin boundary surface, such an effect can be expected.
According to a second aspect of the first light emission source, at least a region of the light reflecting member reached by the light totally reflected by the resin boundary surface constitutes a concave mirror having a focal point at a mirror position of the light emitter with respect to the resin boundary surface. According to the light emission source of this second aspect, the light reflected by the light reflecting member is emitted forward as approximately paralleled light.
According to a third aspect of the first light emission source, distribution field of curvature in the light reflecting surfaces of light reflecting member is different on a pair of mutually perpendicular sections crossing the optical axis of the light emitter. The difference of distribution field of curvature means that the distribution fields of curvature are not the same, and includes the cases that the distribution fields are not mutually overlapped, the distribution fields are partially overlapped but mutually shifted, or one distribution field is wider than another distribution field.
According to the light emission source of the third aspect, because of difference in the distribution fields of curvature in light reflecting plane of the light reflecting member on the mutually perpendicular two sections passing the optical axis of the light emitter, spread of the light reflected by the light reflecting surface varies with its direction even if light emitted from the light emitter is emitted equally in a circumference of the optical axis. For instance, there may be provided a light emission source having an asymmetry directional pattern in a circumference of the optical axis, such as a directional pattern spreading sideways, depending on application.
According to a fourth aspect of the light emission source of the third aspect, an optical lens disposed in a predetermined area in front of the light emitter, and the distribution fields of curvature on a surface of the optical lens are different on mutually perpendicular sections crossing the optical axis of the light emitter. The difference of distribution field of curvature has same meaning in the light reflecting member. According to the light emission source of the fourth aspect, the optical lens condenses the light emitted forward. Since the lens has an asymmetry configuration around the optical axis, the light emitted forward from the light emitter through the lens has a symmetry or ununiform directive pattern around the optical axis. Accordingly, for example, the light emitted forward from a center of the light emitter may be spread sideways on application.
In a second light emission source of this invention including a light emission face in front of a light emitter, the light emission face inclines from a plane perpendicular to the optical axis of the light emitter, whereby disturbance light reflected by the light emission face can be avoided from going in the same direction as that of the light emitted from the light emission source by selecting direction of the light emission face. Accordingly, the light emission source is prevented from hindrance or invisible illumination by the disturbance light reflected by the light emission source.
In a third light emission source having a light emission face in front of a light emitter according to this invention, the light emission face is disposed to turn to the top than horizontal, and at least a part of the light emitted from the light emission face is emitted toward lower part. Since the light emission face is disposed to turn to the top than horizontal and at least a part of the light emitted from the light emission face is emitted toward a lower part in this third light emission source, disturbance light from low altitudes such as the afternoon sun or the morning sun is hard to be reflected back to the lower part even if an apparatus employing this light emission source, for example, a display unit is installed in a high location. On the other hand, since the light from the light emission source is emitted downward, it can be avoided that the display is hard to be seen or that lighting condition and lights-out condition are misunderstood by disturbance light.
According to a fifth aspect of the first light emission source, a light emitter is positioned to be covered by a resin so that light deviated from a predetermined area of front in the light emitted from the light emitter is almost totally reflected by a resin boundary surface, and a light reflecting member is positioned behind the resin boundary surface for reflecting the light emitted from the light emitter to be almost totally reflected by the resin boundary surface, wherein the light reflected by the light reflecting member is emitted slanting against the optical axis of the light emitter. Since the light reflected by the light reflecting member is emitted slanting against the optical axis of the light emitter, the light emission direction can be positioned in a direction different from an installation direction of the light emission source. Accordingly, by emitting light to a desired direction, for example, downward, and installing the light emission source upward, disturbance light such as the afternoon sun or the morning sun is prevented from downward reflection by the light emission source. In this light emission source, the light emitted in a direction having a large angle to the optical axis is totally reflected by the resin boundary surface and further reflected forward by the light reflecting member to be emitted forward from the light emission source, thereby improving the use efficiency of light.
According to a sixth aspect of the first light emission source, at least a region of the light reflecting member reached by the light totally reflected by the resin boundary surface constitutes a concave mirror, and a light emitter is disposed in a location deviated from a mirror position of the focal point of the concave mirror with respect to the resin boundary surface. The light can be emitted toward the optical axis declining against the front of the light emission source, thereby increasing the degrees of freedom of directional pattern of the light emission source.
According to a seventh aspect of the first light emission source, there is provided a second light reflecting member reflecting the light emitted from a side of the light emitter in a forward direction, in which the angle of inclination of the second light reflecting member is set so that most of light reflected by the second light reflecting member can reach the resin boundary surface. The light emitted from the side of the light emitter is reflected by the second light reflecting member to be directly emitted to the external from the predetermined area without emission in a direction largely declining from the optical axis of the light emission source. In other words, the light emitted from the side of the light emitter is reflected by the second light reflecting member to be directed to the resin boundary surface, whereby the light totally reflected by the resin boundary surface is directed to the light reflecting member and its emission direction is controlled by the light reflecting member so as to emit the light in the optical axial direction of the light emission source.
According to an eighth aspect of the light emission source of the seventh aspect, the second light reflecting member is disposed on a lead frame mounted by the light emitter. When the light emitter is disposed on the lead frame, the second light reflecting member may be made by the lead frame, thereby reducing the number of components.
According to a ninth aspect of the first light emission source, at least a part of the light reflecting member comes into contact with an outer circumferential part of the resin composing the resin boundary surface. When the light emission source is produced by resin molding, the light reflecting member can be positioned by hitting an internal circumference part of a metal mold cavity and a location accuracy of the light reflecting member can be easily obtained.
In an light receiver molding a photo detector within a resin according to this invention, a light reflecting member is disposed behind a boundary surface on a light receiving side of the resin so that it reflects the light entering into a region deviated from a predetermined area in front of the photodetector to be totally reflected by a resin boundary surface to be received by the photo detector.
In this light receiver, the light entering into an outside of the photo detector is reflected by the light reflecting member to enter into the photo detector after total reflection by the resin boundary surface, whereby the light receiving area of the light receiver is increased without increasing the area of the photo detector, thereby improving the light receiving efficiency of the light receiver. Moreover, light is gathered by the light reflecting member located behind the boundary surface on the light receiving side of the resin and the resin boundary surface, whereby the light receiver can have a relatively thinned configuration.
According to a first aspect of the light receiver, at least a part of the light reflecting member of the light receiver comes into contact with the outer circumferential part of the resin layer composing the resin boundary surface. According to the light receiver of the first aspect, when the light receiver is produced by resin molding, the light reflecting member can be positioned by hitting an internal circumference part of a metal mold cavity and a location accuracy of the light reflecting member can be easily obtained.
A first optical component according to this invention is an optical module in which a light active element such as a light emitter or a photo detector is mounted on an element mounting position, which includes a resin boundary surface for almost totally reflecting the light deviated from a predetermined area in front of the element mounting position and a light reflecting member. The element mounting position, the resin boundary surface and the light reflecting member are positioned so that a light path from the element mounting position to the external may pass a path which at least reflects back more than once with each of the resin boundary surface and the light reflecting member. The light active element is represented by a solid light emission chip such as an LED (light emitting diode) chip, a light emitter packaging an LED chip, a photo diode, a photo-transistor, or a photoelectric transducer (solar battery cell). The light path from the element mounting position to the external includes a light path from the light active element mounted on the element mounting position to an external of the light active element and the optical module or a light path entering from the external of the light active element and the optical module into the light active element mounted on the element mounting position.
In thus optical component, light emitted from the light active element such as a light emitter in a direction deviating from a predetermined area is totally reflected by a resin boundary surface, and further reflected by the light reflecting member to be externally emitted, whereby a desired directive pattern can be obtained by designing configurations of the resin boundary surface and the light reflecting member. As the light entering from the external is reflected by the light reflecting member, the light emitted in a direction deviating from the predetermined area is totally reflected by the resin boundary surface to enter into the light active element such as a photo detector, whereby desired light receive characteristics can be obtained by designing configurations of the resin boundary surface and the light reflecting member. Moreover, the optical component can be miniaturized and thinned by reflecting back the light with the resin boundary surface and the light reflecting member.
A second optical component according to this invention to be positioned on a front of a light source includes a resin boundary surface for almost totally reflecting the light emitted from the light source and a light reflecting member for reflecting the light almost totally reflected by the resin boundary surface to be emitted forward. According to the second optical component, functions and effects same as the above-mentioned first light emission source can be performed by combining with the light emitter. This optical component is a separate component from the light emitter, whereby its handling is easy because it may be later mounted on the light emitter. This optical component may provide same functions and effects when it is applied to a light source such as an electric lamp or a fluorescent lamp in addition to the light emitter.
A third optical component according to this invention, which is positioned on a front of a photo detector, includes a light reflecting member for reflecting the light entering from an external and a resin boundary surface for totally reflecting the light reflected by the light reflecting member to strike against the photo detector. According to the third optical component, functions and effects same as the above-mentioned light receiver can be performed by combining with the photo detector. This optical component is separate from the photo detector, whereby its handling is easy because it may be later mounted on the photo detector.
According to a first aspect of each of the first, second and third optical components, the optical component includes a recess on an opposite face of each component against the resin boundary surface in order to at least dispose either the light emitter or the photo detector. According to the optical component of the first aspect, the light emitter or the photo detector is disposed within the recess, whereby the light emitter, the photo detector or the optical component can be easily positioned.
According to a second aspect of each of the first, second and third optical components, the optical component includes an engagement portion in order to establish a positional relationship with the optically active element in the element mounting position. The engagement means a complete contact without any spacing. According to this second aspect, since the optical component includes the engagement portion, the optically active element can be mounted without any chattering, and the optical component can be easily positioned with the optically active element.
According to a third aspect of each of the first, second and third optical components, a recess or an open hole is disposed in the position of the element mounting position to enclose or be inserted by the optically active element, whereby the optical component can be three-dimensionally combined with the optically active element to provide a miniaturized construction.
According to a fourth aspect of each of the first, second and third optical components, there is disposed a positioning portion to fix a positional relationship with the optically active element. Accordingly, when the optical component is combined with an optically active element, both members can be positioned by the positioning portion and combined without any chattering, and mutual optical-axis alignment of the members can be easily performed.
According to a fifth aspect of each of the first, second and third optical components, an external configuration of the component viewed from its front includes a major axial direction and a minor axial direction. According to this optical component, for instance, when light emitted from a light emitter is reflected by the optical component to be emitted forward, the light includes a major axial direction and a minor axial direction, in other words, light having an oval light flux section is emitted.
An optical component array in accordance with this invention includes a plurality of the optical components arranged in a desired fashion so as to provide a flat light source. Each optical component can be miniaturized, whereby each light emission point can be minutely made and the optical component array can be thinned.
A second optical device according to this invention includes an arrangement such that the above-mentioned optical component and the above-mentioned optically active element are arranged by a predetermined spacing which is filled with optically transparent materials so as to engage the optical component with the optically active element, whereby the optical component and the optically active element are not necessary to have any high dimensional accuracies and the optical component can be easily manufactured.
According to a sixth aspect of each of the first, second and third optical components, at least a part of the above-mentioned light reflecting member comes into contact with an outer circumferential part of the resin layer providing the resin boundary surface. According to the above-mentioned second aspect of each of the optical components, when the optical component is manufactured by a resin mold, the light reflecting member is put on an internal circumference part of a cavity of a metal mold for fixing the position, thereby easily obtaining a positional accuracy of the light reflecting member.
A manufacturing process of the first optical component including a resin layer having a resin boundary surface for almost totally reflecting the light deviating from a predetermined region in front of a light emitter and a light reflecting member for forwardly emitting the light almost totally reflected by the resin boundary surface according to this invention is provided with a process for resin-injecting at least a part of an outer circumferential part of the light reflecting member striking against an internal surface of a cavity of a metal mold.
According to the manufacturing process of the first optical component of this invention, the first optical component can be produced, and the light reflecting member strikes against an internal circumferential part of the cavity of the metal mold for fixing the position, thereby easily obtaining a positional accuracy of the light reflecting member.
A manufacturing process of the second optical component including a light reflecting member for reflecting the light entering into a region deviating from a predetermined region in front of a photo detector and a resin layer having a resin boundary surface for almost totally reflecting the light reflected by the light reflecting member according to this invention is provided with a process for resin-injecting at least a part of an outer circumferential part of the light reflecting member striking against an internal surface of a cavity of a metal mold.
According to the manufacturing process of the second optical component of this invention, the second optical component can be produced, and the light reflecting member strikes against an internal circumferential part of the cavity of the metal mold for fixing the position, thereby easily obtaining a positional accuracy of the light reflecting member.
In a light emission method according to this invention, the light deviated from a predetermined front area among the light emitted from a light source is almost totally reflected by a resin boundary surface, and the light totally reflected by the resin boundary surface is emitted forward by the light reflecting member disposed behind the resin boundary surface. According to this light emission method, the light deviated from the predetermined area is reflected by the resin boundary surface and the light reflecting member in a light path emitted from the light source, thereby realizing a desired directional pattern by the configurations of the resin boundary surface and the light reflecting member.
In a light incidence method according to this invention, the light deviated from a predetermined area in front of a photo detector among the light entered from an external is almost totally reflected by a light reflecting member, and the light reflected by the light reflecting member is totally reflected by a resin boundary surface to strike against the photo detector. According to this light incidence method, the light deviated from the predetermined area is reflected by the resin boundary surface and the light reflecting member in a light path entering into the photo detector, thereby realizing a desired directional pattern by the configurations of the resin boundary surface and the light reflecting member.
The light emission source and the light receiver according to this invention can be applied to various kinds of apparatuses. For example, the photoelectric sensor according to this invention includes the light receiver employing a photoelectric transducer as a photo detector according to this invention and a light projecting element, in which the light emitted by the light projecting element or the light emitted by the light projecting element and reflected by an object is detected by the light receiver. A self light generating apparatus according to this invention includes the light receiver employing a photoelectric transducer as the photo detector according to this invention, a battery charger for charging electric energies generated by the light receiver, and a light receiver. A display apparatus according to this invention is arranged by a plurality of light emission sources according to this invention or a plurality of optical components according to this invention. A light source for an automobile lamp according to this invention is arranged by a plurality of light emission sources according to this invention or a plurality of optical components according to this invention. An outdoor display apparatus according to this invention is arranged by a plurality of light emission sources according to this invention or a plurality of optical components according to this invention.
The above-mentioned components of construction can be optionally combined as far as possible.
FIG. 1 is a sectional view of a conventional light emission source;
FIG. 2 is a sectional view of another conventional light emission source;
FIG. 3 is a sectional view of a light emission source according to a first embodiment of this invention;
FIG. 4 shows at (a) the light emission source of FIG. 3 and a light quantity distribution of the same, and at (b) a light quantity distribution of a conventional light emission source;
FIG. 5 is a sectional view of a light emission source according to a second embodiment of this invention;
FIG. 6 is a sectional view of a light emission source according to a third embodiment of this invention;
FIG. 7 is a sectional view of a light emission source according to a fourth embodiment of this invention;
FIG. 8 is a sectional view of a light emission source according to a fifth embodiment of this invention;
FIG. 9 is a perspective view of a mold resin employed in the light emission source of FIG. 8;
FIG. 10 is a sectional view of the light emission source of FIG. 8;
FIG. 11 is a magnified view of a portion A of FIG. 8;
FIG. 12 is a sectional view of a light emission source according to a sixth embodiment of this invention;
FIG. 13 is a sectional view of a light emission source according to a seventh embodiment of this invention;
FIG. 14 is a sectional view of a light emission source according to an eighth embodiment of this invention;
FIG. 15 is a sectional view of a light emission source according to a ninth embodiment of this invention;
FIG. 16 is a sectional view of a light emission source according to a tenth embodiment of this invention;
FIG. 17 is a sectional view of a light emission source according to an eleventh embodiment of this invention;
FIG. 18 is a sectional view of a light emission source according to a twelfth embodiment of this invention;
FIG. 19 is a sectional view of a light emission source according to a thirteenth embodiment of this invention;
FIG. 20 is a sectional view of a light emission source according to a fourteenth embodiment of this invention;
FIG. 21 is a sectional view of a light emission source according to a fifteenth embodiment of this invention;
FIG. 22 shows color splitting in a conventional light emission source in a two chip-shape
FIG. 23 is a sectional view of a light emission source according to a sixteenth embodiment of this invention;
FIG. 24 is a sectional view of a light emission source according to a seventeenth embodiment of this invention;
FIG. 25 shows at (a) a front enlarged view of a lead frame employed in the light emission source of FIG. 24, and at (b) a partially broken side view of the same;
FIG. 26 is an enlarged sectional side view of a portion of FIG. 24 to express light movement;
FIG. 27 is a sectional view showing an embodiment to be compared with the embodiment of FIG. 24;
FIG. 28 is a view showing light movement in the embodiment of FIG. 27;
FIG. 29 is a sectional view of a light emission source according to an eighteenth embodiment of this invention;
FIG. 30 is a perspective view of a light receiver according to a nineteenth embodiment of this invention;
FIG. 31 is a sectional view of the light receiver of FIG. 30;
FIG. 32 is a sectional view of a light receiver according to a twentieth embodiment of this invention;
FIG. 33 is a perspective view of a light receiver according to a twenty-first embodiment of this invention;
FIG. 34 is a perspective view of a light receiver according to a twenty-second embodiment of this invention;
FIG. 35 shows at (a) a front view of the light emission source of FIG. 34, at (b) a sectional view taken along line X 1 -X 1 of FIG. 35 at (a), and at (c) a sectional view taken along line Y 1 -Y 1 of FIG. 35 at (a);
FIG. 36 shows a profile of light beams emitted by the light emission source of FIG. 34;
FIG. 37 shows an intensity distribution of light emitted by the light emission source of FIG. 34;
FIG. 38 shows at (a) a perspective view of a light reflection portion having a biconical surface, and at (b) a relationship between the biconical surface and the coordinate;
FIG. 39 shows at (a) a front view of a light emission source according to a twenty-third embodiment of this invention, at (b) a sectional view taken along line X 2 -X 2 of FIG. 39 at (a), and at (c) a sectional view taken along line Y 2 -Y 2 of FIG. 39 at (a);
FIG. 40 shows a profile of light beams emitted by the light emission source of FIG. 39;
FIG. 41 shows at (a) a front view of a light emission source according to a twenty-fourth embodiment of this invention, at (b) a sectional view taken along line X 3 -X 3 of FIG. 41 at (a), and at (c) a sectional view taken along line Y 3 -Y 3 of FIG. 41 at (a);
FIG. 42 shows a profile of light beams emitted by the light emission source of FIG. 41;
FIG. 43 shows at (a) a front view of a light emission source according to a twenty-fifth embodiment of this invention, at (b) a sectional view taken along line X 4 -X 4 of FIG. 43 at (a), and at (c) a sectional view taken along line Y 4 -Y 4 of FIG. 43 at (a);
FIG. 44 shows at (a) a front view of a light emission source as a modification of the twenty-fifth embodiment, at (b) a sectional view taken along line X 5 -X 5 of FIG. 44 at (a), and at (c) a sectional view taken along line Y 5 -Y 5 of FIG. 44 at (a);
FIG. 45 shows at (a) movements of light emitted at an edge of a resin boundary surface in a light emission source having no slant wall, and at (b) movements of light emitted at an edge of a resin boundary surface in a light emission source having a slant wall;
FIG. 46 shows at (a) a front view and at (b) a sectional view of a light emission source according to a twenty-sixth embodiment of this invention;
FIG. 47 is a front view of a light emission source according to a twenty-seventh embodiment of this invention;
FIG. 48 is a front view of a light receiver according to a twenty-eighth embodiment of this invention;
FIG. 49 is a sectional view of the light receiver of FIG. 48;
FIG. 50 shows at (a) a front view and at (b) a perspective view of photo detectors which can be employed in the light receiver of FIG. 48;
FIG. 51 is a sectional view of a light emission source according to a twenty-ninth embodiment of this invention;
FIG. 52 is a sectional view of a light emission source according to a thirtieth embodiment of this invention;
FIG. 53 is a sectional view of a light emission source according to a thirty-first embodiment of this invention;
FIG. 54 shows an enlarged view of a portion of FIG. 53;
FIG. 55 is a sectional view of a light emission source according to a thirty-second embodiment of this invention;
FIG. 56 shows an enlarged view of a portion of FIG. 55;
FIG. 57 shows at (a) a sectional view of a light emission source according to a thirty-third embodiment of this invention, and at (b) a front view of an optical module;
FIG. 58 is a sectional view of a light emission source according to a thirty-fourth embodiment of this invention;
FIG. 59 is a sectional view of a light emission source according to a thirty-fifth embodiment of this invention;
FIG. 60 is a sectional view of a light emission source according to a thirty-sixth embodiment of this invention;
FIG. 61 is a sectional view of a light emission source according to a thirty-seventh embodiment of this invention;
FIG. 62 is a sectional view of a light emission source according to a thirty-eighth embodiment of this invention;
FIG. 63 is a sectional view of a light emission source according to a thirty-ninth embodiment of this invention;
FIG. 64 is a sectional view of a light emission source according to a fortieth embodiment of this invention;
FIG. 65 is a sectional view of a light emission source according to a forty-first embodiment of this invention;
FIG. 66 at (a) to (c) shows a manufacturing process for the above-mentioned light emission source;
FIG. 67 shows a sectional view of a modification of the forty-first embodiment;
FIG. 68 is a sectional view of a light emission source according to a forty-second embodiment of this invention;
FIG. 69 is a sectional view of a light emission source according to a forty-third embodiment of this invention;
FIG. 70 shows a sectional view of a modification of the forty-third embodiment;
FIG. 71 shows a sectional view of a modification of the forty-third embodiment;
FIG. 72 is a sectional view of a light emission source according to a forty-fourth embodiment of this invention;
FIG. 73 is a sectional view of a light receiver according to a forty-fifth embodiment of this invention;
FIG. 74 is a sectional view of a light receiver according to a forty-sixth embodiment of this invention;
FIG. 75 is a sectional view of a light emission source according to a forty-seventh embodiment of this invention;
FIG. 76 shows a sectional view of a modification of the forty-seventh embodiment;
FIG. 77 shows a sectional view of another modification of the forty-seventh embodiment;
FIG. 78 shows a sectional view of another modification of the forty-seventh embodiment;
FIG. 79 shows a sectional view of another modification of the forty-seventh embodiment;
FIG. 80 is a sectional view of a light emission source according to a forty-eighth embodiment of this invention;
FIG. 81 shows a manufacturing process for a light emission source according to a forty-ninth embodiment of this invention;
FIG. 82 is a perspective view of a light emission source array according to a fiftieth embodiment of this invention;
FIG. 83 is a sectional view of the above-mentioned light emission source array;
FIG. 84 shows a sectional view of a modification of the fiftieth embodiment;
FIG. 85 shows an arrangement of light emission sources in a light emission source array;
FIG. 86 shows an arrangement of light emission sources in a light emission source array;
FIG. 87 shows an arrangement of light emission sources in a light emission source array;
FIG. 88 shows an arrangement of light emission sources in a light emission source array;
FIG. 89 at (a) and (b) shows sectional and front views of a construction of a light emission source according to a fifty-first embodiment of this invention;
FIG. 90 at (a) and (b) shows sectional and front views of a construction of the light reflection member employed in the light emission source of FIG. 57;
FIG. 91 is an operation explanatory view of the light emission source of FIG. 57;
FIG. 92 shows light distribution characteristics of the light emission source of FIG. 57;
FIG. 93 is a front view of a signal according to a fifty-second embodiment of this invention;
FIG. 94 is a side view of the signal of FIG. 61;
FIG. 95 is a sectional view of a signal lamp providing the signal of FIG. 61;
FIG. 96 shows a direction of light emitted from the signal of FIG. 61;
FIG. 97 is a sectional view of a comparative example of a signal lamp;
FIG. 98 is a front view of a light emission display apparatus according to a fifty-third embodiment of this invention;
FIG. 99 is a front view of a light emission display unit providing the display apparatus of FIG. 66;
FIG. 100 is a side view of the light emission display unit of FIG. 67;
FIG. 101 is a side view a comparative example of alight emission display unit;
FIG. 102 is a sectional view of a light emission source according to a fifty-fourth embodiment of this invention;
FIG. 103 is a sectional view of a light emission source according to a modification of the fifty-fourth embodiment of this invention;
FIG. 104 is a sectional view of a light emission source according to a fifty-fifth embodiment of this invention;
FIG. 105 is a sectional view of a light emission source according to a modification of the fifty-fifth embodiment of this invention;
FIG. 106 is a sectional view of a light emission source according to a fifty-sixth embodiment of this invention;
FIG. 107 shows a different shape front of the light emission source;
FIG. 108 shows a further different shape front of the light emission source;
FIG. 109 shows a still further different shape front of the light emission source;
FIG. 110 shows a still further different shape front of the light emission source;
FIG. 111 is a sectional view of a light emission source according to a fifty-seventh embodiment of this invention;
FIG. 112 is a sectional view of a light emission source according to a modification of the fifty-seventh embodiment of this invention;
FIG. 113 is a sectional view of a light emission source according to a fifty-eighth embodiment of this invention;
FIG. 114 is a sectional view of a light emission source according to a fifty-ninth embodiment of this invention;
FIG. 115 is a sectional view of alight emission source according to a modification of the fifty-ninth embodiment of this invention;
FIG. 116 is a sectional view of alight emission source according to a sixtieth embodiment of this invention;
FIG. 117 is a sectional view of alight emission source according to a modification of the sixtieth embodiment of this invention;
FIG. 118 is a sectional view of a light emission source according to a modification of the fifty-fourth embodiment of this invention;
FIG. 119 is a sectional view of a light emission source according to another modification of the fifty-fourth embodiment of this invention;
FIG. 120 is a sectional view of a light emission source according to a sixty-first embodiment of this invention;
FIG. 121 shows front and side views of an outdoor display apparatus according to a sixty-second embodiment of this invention;
FIG. 122 is a side view of the outdoor display apparatus of FIG. 89 ( 121 ) on use;
FIG. 123 shows a manufacturing process for a light emission source according to a sixty-third embodiment of this invention;
FIG. 124 is a perspective view of a light emission display according to sixty-fourth of this invention;
FIG. 125 shows at (a) a perspective view of a conventional light emission source employed in a light emission display, and at (b) an arrangement of the light emission source;
FIG. 126 is a perspective view of an external configuration of a light emission source employed in the light emission display of FIG. 92 ( 124 );
FIG. 127 shows one picture element of a full color light emission display in which a red light emission source, a green light emission source, a blue light emission source are arranged in a delta fashion;
FIG. 128 is a schematic diagram showing an optical fiber coupler according to a sixty-fifth embodiment of this invention;
FIG. 129 is a schematic diagram showing a signal lamp according to a sixty-sixth embodiment of this invention;
FIG. 130 is a schematic diagram showing an advertisement signboard according to a sixty-seventh embodiment of this invention;
FIG. 131 is a schematic diagram showing an advertisement signboard according to a modification of the sixty-seventh;
FIG. 132 is a perspective view of a high mount strap lamp according to a sixty-eighth embodiment of this invention;
FIG. 133 is a perspective view of a single light emission source employed in the high mount strap lamp of FIG. 100 ( 132 );
FIG. 134 is a perspective view of a high mount strap according to a sixty-ninth embodiment of this invention;
FIG. 135 is a perspective view of the high mount strap of FIG. 102 ( 134 ) installed into a car;
FIG. 136 shows at (a) an enlarged sectional view of a portion of the high mount strap of FIG. 102 ( 134 ), and at (b) a front view of the same;
FIG. 137 shows at (a) an enlarged sectional view of a portion of a conventional high mount strap, and at (b) a front view thereof;
FIG. 138 is a perspective view of a display apparatus according to a seventieth embodiment of this invention;
FIG. 139 is a perspective view showing a beam configuration of light emitted from a light emission source employed in the display apparatus of FIG. 106 ( 138 );
FIG. 140 is a perspective view showing an area where display by the display apparatus of FIG. 106 ( 138 ) can be recognized;
FIG. 141 is a sectional view of a photoelectric sensor according to a seventy-first embodiment of this invention;
FIG. 142 is a sectional view of a road tack according to a seventy-second embodiment of this invention;
FIG. 143 is a perspective view of an illumination-type switch according to a seventy-third embodiment of this invention;
FIG. 144 is a disassembled perspective view of the illumination-type switch according of FIG. 111 ( 143 );
FIG. 145 is a schematic sectional view of the illumination-type switch according of FIG. 111 ( 143 ); and
FIG. 146 is a schematic sectional view of a conventional illumination-type switch.
Embodiments of this invention will be described in detail hereinafter referring to drawings.
As a first embodiment, a section of a light emission source 11 is shown in FIG. 3. According to this embodiment, a light emitter 12 of a light emitting diode (LED chip) is sealed in a mold resin 13 made of optically transparent resin materials. The light emitter 12 sealed in the mold resin 13 is mounted on a stem 15 disposed on a leading edge of a lead frame 17 , and connected with another lead frame 14 by a bonding wire 16 so that a light emission side is disposed toward a front of the light emission source 11 .
In a front central part of the mold resin 13 , there is disposed a direct emission region 18 having a convex lens configuration such as a spherical lens shape, an aspherical lens shape, or a paraboloid shape. A total reflection region 19 in a flat shape is formed to surround the direct emission region 18 . The direct emission region 18 is formed so that its medial axis can accord with medial axis of the light emitter 12 , and the total reflection region 19 is formed to be a flat plane perpendicular to an optical axis of the light emitter 12 . The light emitter 12 is located in focal point of the direct emission region 18 or the neighborhood. The angle α of a direction, viewed from the light emitter 12 to the boundary between the direct emission region 18 and the total reflection region 19 , from the optical axis of the light emitter 12 is equal to a critical angle θ c of total reflection between the mold resin 13 and air or larger.
Therefore, light emitted to the direct emission region 18 in the light emitted from the light emitter 12 is emitted approximately in parallel directly from a front of the mold resin 13 to front. Light emitted to the total reflection region 19 in the light emitted from the light emitter 12 is totally reflected by its resin boundary surface to be directed to a rear face of the mold resin 13 .
The rear face of the mold resin 13 is coated with a metal film having a high reflectivity such as aluminum or silver by vacuum deposition or a multilayer reflection film to provide a light reflection portion 20 . At least a region of the light reflection portion 20 hit by the light reflected by the total reflection region 19 provides a concave mirror, such as a spherical mirror or revolution-parabolic mirror, having a focal point around a mirror position of the light emitter 12 with respect to the total reflection region 19 .
Accordingly, light emitted from the light emitter 12 and totally reflected by the total reflection area 19 strikes against the light reflection portion 20 to be reflected thereby and emitted forward from the total reflection region 19 in approximately parallel.
Therefore, according to the light emission source 11 of this embodiment, approximately all light forwardly emitted from the light emitter 12 (including the light totally reflected by the total reflection region 19 ) can be taken toward a forward direction of the light emission source 11 , resulting into high efficiency of light use. Moreover, the light emitted forward from the light emitter 12 can be emitted from the direct emission region 18 without any obstruction, whereby darkness on the optical axis as found in a conventional light emission source can be avoided and the directional pattern also can be improved.
Furthermore, the light emitted from the light emitter 12 in a diagonal direction is totally reflected by the total reflection region 19 and further reflected by the light reflection portion 20 for forward emission, whereby the optical path length is elongated, thereby reducing its aberration and providing a high accuracy of the light emission source 11 .
In a conventional light emission source employing a light emitting diode, most of light totally reflected by a mold resin is not emitted forward, thereby providing a narrow distribution about quantity of light as shown in FIG. 4 at (b). As shown in FIG. 4 at (a), according to the light emission source 11 of this embodiment, the light emitted from the light emitter 12 is spread over a whole front face of the mold resin 13 and approximately paralleled, thereby providing a width-wide and uniform distribution of light quantity (beam profile).
In this embodiment, the light emission source is designed to emit the paralleled light. If desired, the directional pattern of the light emitted from the light emitter 11 can be changed to a desired pattern by changing the position of the light emitter 12 , the focal position and the surface configuration of the direct emission region 18 providing a convex lens, or the focal position and the surface configuration of the light reflection portion 20 providing a concave mirror.
FIG. 5 shows a sectional view of a light emission source 21 according to a second embodiment. FIG. 5 omits the components of a stem, a lead frame, and a bonding wire (delineation of lead frame and others might be omitted in a light emission source shown in FIG. 6 and its subsequent figures). In this embodiment, a direct emission region 18 in a boundary surface of a mold resin 13 is formed to be flat. Accordingly, direct emission region 18 and total reflection region 19 cannot be distinguished from their appearance, but can be distinguished by the movement of light beams emitted from a light emitter 12 . The position of the light striking against a boundary surface of the mold resin 13 from the light emitter 12 at a critical angle θ c of its total reflection becomes a boundary of the direct emission region 18 and the total reflection boundary 19 . Therefore, the incident light striking against the direct emission region 18 inside of the boundary is directly emitted from the direct emission region 18 , and the light striking against the total reflection region 19 outside of the boundary is totally reflected by the total reflection region 19 to be reflected by a light reflection portion 20 for forward emission.
In this embodiment, total reflection is made by the boundary surface of the mold resin 13 , and the efficiency of light use is improved also. The direct emission region 18 is formed to be plane, whereby the light emitted from the direct emission region 18 is spread and the angle of beam spread of light emitted from the region can be broadly widened. When the angle of beam spread is desired to be widened or the limitation to the angle is minor, the direct emission region 18 can be formed to be flat so as to simplify the front configuration of the mold resin 13 like this embodiment.
FIG. 6 is a sectional view of a light emission source 22 according to a third embodiment, in which a front portion 18 a of a direct emission region 18 is formed to be larger than a base portion 18 b and to provide a lens configuration. When the light totally reflected by a resin boundary surface and further reflected by a light reflection portion 20 is approximately paralleled, a region where any light is not emitted appears in an internal circumference portion of a total reflection region 19 , so that the lens configuration of the direct emission region 18 can have a large diameter without narrowing the total reflection region 19 by enlarging the front portion 18 a of the direct emission region 18 as far as light emitted from the total reflection region 19 is not obstructed. According to this configuration, the ratio of the light emitted from the direct emission region 18 of a lens configuration and the light emitted from the total reflection region 19 can be efficiently designed, thereby providing a high performance of the light emission source 22 .
In the light emission source 11 shown in FIG. 3, the light striking against an edge (outer circumferential portion) of the direct emission region 18 is blocked so that it cannot be emitted forward, whereby the blocked light emitted from the light emitter 12 becomes loss. When the distance between the light emitter 12 and the direct emission region 18 is short, the curvature of the direct emission region 18 becomes large, whereby the light emitted to the edge of the direct emission region 18 can be emitted in a traverse direction or totally reflected. Moreover, the edge of the direct emission region 18 has to be positioned outside of a direction of an angle from the medial axis of the light emitter 12 which is equal to the critical angle of total reflection, so that because of a lower limit in the dimension (diameter viewed from the front) of the direct emission region, area of the circumference part of the direct emission region 18 becomes large and loss of light emitted from the light emitter 12 becomes large. Moreover, because of a lower limit in the dimension of the direct emission region 18 , the curvature of a surface of the direct emission region 18 also has an upper limit and the design flexibility of the direct emission region 18 is limited.
In view of the above, FIG. 7 shows a sectional view of a light emission source 23 according to a fourth embodiment, in which a direct emission region 18 is disposed in the center of a surface of a mold resin 13 and a total reflection region 19 is disposed outside its circumference. The direct emission region 18 has a generally hemispheric shape, and its medial axis accords with an optical axis C of light emitter 12 . In the light emission source 23 , the light emitted from the light emitter 12 toward the direct emission region 18 is refracted-and emitted approximately forward from the direct emission region 18 .
The total reflection region 19 is composed of a taper-shaped portion 19 b in a conical (block) shape or a pyramid (block) shape, and a flat portion 19 a , wherein a medial axis of the taper-shaped portion 19 b agrees with an optical axis C of the light emitter 12 , and the flat portion 19 a has a face perpendicular to the optical axis C of the light emitter 12 . The section of the taper-shaped portion 19 b passing the medial axis is straight but may be curve. For example, the taper-shaped portion 19 b may be a surface of revolution of curve with a rotation axis representing the medial axis.
The angle θ b of a direction, which is viewed from the light emitter 12 to a boundary between the flat portion 19 a and the taper-shaped portion 19 b , from the optical axis C of the light emitter 12 is designed to be larger than the critical angle θ c of the total reflection in the boundary surface of the mold resin 13 (for example, against air). Therefore, all light emitted from the light emitter 12 and striking against the flat portion 19 a is reflected by the flat portion 19 a so as to be directed to a light reflecting portion 20 .
In addition, the angle θ a of the direction, which is viewed from the light emitter 12 to an edge of the direct emission region 18 (the boundary between the direct emission region 18 and the taper-shaped portion 19 b ), from the optical axis C of the light emitter 12 is designed to be smaller than the critical angle θ c of the total reflection in the boundary surface of the mold resin 13 (for example, against air). In other words, when viewed from a front, the dimension of the direct emission region 18 is smaller, and the sharing ratio of the outré circumferential part of the direct emission region 18 against the all is smaller, in comparison with the light emission source 11 shown in FIG. 3. Accordingly, the light lost by the sideway emission at an edge of the direct emission region 18 or total reflection in the light emission source shown in FIG. 3 is totally reflected by the taper-shaped portion 19 b and reflected by the light reflecting portion 20 to be emitted forward, thereby decreasing the loss of light. Since the direct emission region 18 is small, the curvature in the surface of the direct emission region 18 can be large, thereby decreasing the constraint of design.
All light striking against the taper-shaped portion 19 b is totally reflected by the taper-shaped portion 19 b . For example, when the section of the taper-shaped portion 19 b is designed to be straight as shown in FIG. 7 and θ c is assumed to be a critical angle of the total reflection, the and gradient β of the taper-shaped portion 19 b is designed by the equation below;
β≧θ c−θ a
Therefore, all light emitted from the light emitter 12 to strike against the taper-shaped portion 19 b is totally reflected by the taper-shaped portion 19 b to be directed toward the light reflecting portion 20 .
The configuration of the light reflecting portion 20 is designed so that the light totally reflected by the flat portion 19 a and the taper-shaped portion 19 b is reflected by the light reflecting portion 20 to be emitted forward from the total reflection region 19 .
Therefore, according to this embodiment, the loss of light is reduced, and the design flexibility of the direct emission region 18 is improved.
FIGS. 8 and 10 show perspective and sectional views of a light emission source 24 according to a fifth embodiment of this invention. FIG. 9 shows a perspective view showing an inner component of the light emission source 24 viewed through a mold resin 13 . FIG. 11 is an enlarged view of a portion A of FIG. 10. The light emission source 24 employs a light reflecting portion 20 which has a parabola-shaped metal member formed by press working and is plated with aluminum or silver on a surface of the portion for a specular working. If desired, the light reflecting portion 20 may employ a pressing part with aluminum or silver which is chemically processed to bring glossiness on a surface thereof.
The light reflecting portion 20 at a core thereof includes an aperture 20 a for accommodating a stem 15 . The stem 15 mounted by a light emitter 12 is put without any contact with the aperture 20 a , and the light reflecting portion 20 is sealed within a mold resin 13 together with lead frames 14 and 17 .
On a front wall of the mold resin 13 , there are formed a direct emission region 18 in the center of the resin, a taper-shaped portion 19 b around the region, and a flat portion 19 a around the portion 19 b , in the same manner as the configuration of the embodiment shown in FIG. 7.
According to this light emission source 24 having such above-mentioned construction, any evaporation film (light reflecting portion 20 ) is not necessary to be disposed on a rear wall of the mold resin 13 as shown in the embodiment of FIG. 3, and the light reflecting portion 20 formed together with the light emitter 12 and the lead frames 14 and 17 as a single isolated unit has only to be set within a molding metal mold, thereby simplifying the manufacturing process.
As shown in FIG. 11, an outer circumference portion of a front of the mold resin 13 is provided with a taper-shaped beveling portion 25 , and an angle of outer circumferential face of the light reflecting portion 20 is designed to accord with an angle B of the beveling portion 25 . Accordingly, when the mold resin 13 is molded, setting can be done while angle of the outer circumference at a reflection side of the light reflecting portion 20 strikes against an inner wall of a cavity of the molding metal mold, the light reflecting portion 20 can be fixed its position to be precisely inserted within the mold resin 13 , thereby improving the mounting accuracy of the light reflecting portion 20 .
FIG. 12 is a sectional view of a light emission source 26 according to a sixth embodiment of this invention. This light emission source 26 has a similar construction to that of the fifth embodiment, but a total reflection region 19 is composed of only a flat portion perpendicular to an optical axis of a light emitter 12 .
In addition, at least a region of the light reflecting portion 20 stricken by the light reflected by the total reflection region 19 serves as a concave mirror, such as a spherical mirror or a parabolic mirror of revolution, having a focal point at a position of a mirror image 12 a of the light emitter 12 with respect to the total reflection region 19 , as similarly described in the first embodiment. Accordingly, the light emitted from the light emitter 12 , totally reflected by the total reflection region 19 , and reflected by the light reflecting portion 20 passes through the total reflection region 19 to be emitted forward as paralleled light.
FIG. 13 is a sectional view of a light emission source 27 according to a seventh embodiment of this invention, in which a total reflection region 19 has a reverse circular cone-shaped configuration. Since the total reflection region 19 is formed to have the reverse circular cone-shaped configuration so that its outer circumferential portion appears forward, an incident angle of light emitted from the light emitter 12 and striking against the total reflection region 19 can be designed to be large, whereby an aperture of an inner circumference portion of the total reflection region 19 can be made small. Accordingly, the ratio of light totally reflected by the total reflection region 19 and reflected by the light reflection portion 20 to be emitted from the total reflection region 19 can be large, whereby a light emission source having an optional directivity can be easily realized by optimally designing the configuration of the light reflecting portion 20 .
Though not shown, the total reflection region 19 may be modified to have a circular cone-shaped configuration so that its outer peripheral potion appears backward. When the total reflection region 19 has the circular cone-shaped configuration, the light emitted from the total reflection region 19 can be gathered inner side, whereby a dark area near the direct emission region 18 can be minimized.
FIG. 14 is a sectional view of a light emission source 28 according to an eighth embodiment. In this light emission source 28 , a front wall of a mold resin 13 is formed to have a curved surface on which a direct emission region 18 and a total reflection region 19 are smoothly formed, whereby most of light emitted forward from a light emitter 12 is totally reflected by the front wall of the mold resin 13 (the total reflection region 19 ) and reflected by a light reflecting portion 20 to be emitted forward. According to the light emission source 28 of such a configuration, the design flexibility of the light emission source 28 is improved.
FIG. 15 is a sectional view of a light emission source 29 according to a ninth embodiment. In this embodiment, a total reflection region 19 has a continuously varying curved face such as lens-curved face, and the degree of freedom of design is further improved.
FIG. 16 is a sectional view of a light emission source 30 according to a tenth embodiment. In the light emission source 30 of this embodiment, a lens configuration of a lens-shaped direct emission region 18 is formed to be a Fresnel lens to decrease the thickness of the direct emission region 18 or the light emission source 30 .
FIG. 17 is a sectional view of a light emission source 31 according to an eleventh embodiment. In the light emission source 31 of this embodiment, a rear face of a mold resin 13 is formed to include a Fresnel lens on a surface of which a light reflecting portion 20 is formed. In this embodiment, the thickness of the light emission source 31 can be reduced.
FIG. 18 is a sectional view of alight emission source 32 according to a twelfth embodiment. In this embodiment, a mirror 33 is disposed near a light emitter 12 within a mold resin 13 so as to reflect the light emitted sideway from the light emitter 12 toward a total reflection region 19 . The light reflected by the mirror is totally reflected by the total reflection region 19 , and further reflected by a light reflecting member 20 to be emitted forward from the total reflection region 19 . If desired, the mirror 33 may be formed on an inner wall of a stem 15 (see FIG. 24).
According to this embodiment, the light emitted sideway in the light emitted from the light emitter 12 is directly reflected by the light reflecting portion 20 to be avoided from becoming lost light, whereby the light emitted in a side direction is effectively used and the use efficiency of light emitted from the light emitter 12 is further improved.
FIG. 19 is a sectional view of alight emission source 34 according to a thirteenth embodiment. In this embodiment, a light emitter 12 is disposed in the location deviated from an optical axis D of a mold resin. Since the light emitter 12 is located apart from a direct emission region 18 and a total reflection region 19 , so that biased light is emitted from the light emission source 34 in an inclined direction. In other words, the directional pattern can be asymmetry within a face which light emitter 12 is inclined.
FIG. 20 is a sectional view of a light emission source 35 according to a fourteenth embodiment of this invention. The light emission source 35 of this embodiment has a similar construction to that of the light emission source 26 as shown in FIG. 12, but the position of light emitter 12 is shifted from the center of light reflecting portion 20 and an optical axis D of direct emission region 18 .
In other words, the light emitter 12 is disposed at a little displaced location to a direction perpendicular to the optical axis of the direct emission region 18 . At least a region of the light reflecting portion 20 stricken by the light reflected by total reflection region 19 serves as a concave mirror, such as a spherical mirror or a parabolic mirror of revolution, and a center of the light reflecting portion 20 is disposed so as to accord with the optical axis D of the direct emission region 18 . The concave mirror and the light emitter 12 have a positional relationship such that a mirror image 12 a of the light emitter 12 with respect to the total reflection region 19 is located at a position apart from a focal point of the concave mirror in a wall which passes the focal point of the concave mirror and is perpendicular to the optical axis of the concave mirror. In other words, the light emitter 12 is disposed at the location displaced from a mirror image position of the focal point of the concave mirror with respect to the total reflection region 19 .
Therefore, in this light emission source 35 , the light emitted from the light emitter 12 passes the direct emission region 18 to be emitted in a diagonal direction as approximately paralleled light. The light emitted from the light emitter 12 , totally reflected by total reflection region 19 and further reflected by the light reflecting portion 20 is emitted in a diagonal direction as approximately paralleled light.
FIG. 21 is a sectional view of a light emission source 36 according to a fifteenth embodiment. In this embodiment, a plurality of light emitters 12 R and 12 G having different light emission colors respectively (for example, a red light emitting diode, a green light emitting diode) are sealed within the mold resin 13 .
When a plurality of light emitters each in a chip shape are enclosed within the mold resin in a cannonball-shaped light emission source 37 (a comparative example) as shown in FIG. 22, the color isolation is large and varies depending on a viewing direction, and visual performance depends on the viewing direction. In the light emission source 36 of this invention, the difference of degrees of color isolation by its viewing direction can be small, and its visual performance can be uniformed.
FIG. 23 is a sectional view of a light emission source 38 according to a sixteenth embodiment. In this embodiment, an optical multilayer film 39 is formed over a whole front wall of a mold resin 13 . By forming the optical multilayer film 39 on the front wall of the mold resin 13 , the light having an incident angle larger than a particular angle is reflected by a boundary surface and the light having an incident angle smaller than the particular angle is driven to pass through. Moreover, the particular angle can be optionally chosen by design of the optical multilayer film 39 , thereby increasing the degree of freedom of the design. The light emission source including the optical multilayer film 39 may be any of light emission sources shown in FIGS. 3 to 20 or other light emission source, if desired.
FIG. 24 is a sectional view of a light emission source 41 according to a seventeenth embodiment. Before describing the light emission source 41 of this embodiment, embodiments for comparison will be described hereinafter to ease understanding this embodiment.
For instance, in the light emission source as shown in FIG. 10 or 12 , the cup in a parabola shape (light reflecting member) is disposed on the stem 15 at a top end of the lead frame 17 so that the light emitter 12 mounted within the stem 15 is surrounded by the cup. This is because the light emitted from a side wall of the light emitter 12 (LED bare chip) is reflected by an inner surface of the cup to be emitted forward. Thus cup within the stem is conventionally employed, but the conventional cup is slanted toward roughly 45 degrees against the optical axis of the light emitter.
FIG. 27 shows an embodiment in which a conventional cup 40 is employed in the light emission source shown in FIG. 12 as it is. The optical axis of light emitted from direct emission region 18 is fixed by an angle connecting a light emission point with a principal point of the direct emission-region 18 . The light emitted by the cup 40 can be regarded as the light where the cup 40 is a virtual light source. Namely, a mirror image of the light emitter 12 with respect to the cup 40 appears in a ring shape near an outer circumference of an inner wall of the cup 40 . The distance between the light emitter 12 and the cup 40 , however, is very short, so that the mirror image of the light emitter 12 appears very near the cup 40 , or almost accords with the cup 40 . As shown in FIG. 27, the light emitted after reflection by the cup 40 can be regarded as the light emitted from respective points on a surface of the cup 40 (virtual light source), so that an optical axis of the light which is emitted from the light emitter 12 , reflected by the cup 40 and emitted from the direct emission region 18 declines, and the light is emitted in a slant direction.
In a conventional light emission source with the use of this cup 40 (for example, a cannonball shape as shown in FIG. 22), the distance between the light emitter and the lens is long, so that the gradient of the optical axis of such emitted light is small, so that any substantial problem has not happened. In the light emission source of this invention, the distance between the light emitter 12 and the direct emission region 18 is short, so that the gradient of the optical axis of the emitted light reflected by the cup 40 becomes large, whereby the light which is emitted forward from the light emitter and the light which is emitted from a side of the light emitter 12 and reflected by the cup 40 cannot be emitted in approximately same direction.
As a result, when the light emission source of this invention employs a conventional cup having a gradient roughly 450 the light emitted from the light emitter 12 is mixed with the light L 1 emitted in approximately in the optical axis and the light L 2 emitted in a direction greatly deviated from the optical axis. In particular, as it becomes far from the light emission source, the light emitted in different directions is split so that the light L 2 appears in a ring shape around the light L 1 . Moreover, the direct emission region 18 cannot be designed together with the front light and the sideway light of the light emitter 12 , whereby the optical lens is designed about the front light, and the optical axis of the slant light L 2 cannot be controlled by the design of a lens shape of the direct emission region 18 .
The above-mentioned embodiments are improved by stem 15 in this seventeenth embodiment. The light emission source 41 of FIG. 24 employs a similar construction to the embodiment shown in FIG. 12, and provides an improvement. FIG. 25 at (a) and (b) shows a front view of a lead frame and a partially sectional side view of the same. In this embodiment, stem 15 also is disposed for mounting light emitter 12 , and a cup 42 for light reflection is disposed around amounting position for the light emitter on the stem 1 . The light emitter 12 is mounted on an inside face of the cup 42 on a front wall of the stem 15 . As shown in FIG. 26 which is a partially magnified view of FIG. 24, the configuration of the cup 42 is designed so that the light emitted sideway from the light emitter 12 and reflected by the cup 42 can be directed to the total reflection region 19 without going to the direct emission region 18 . As concretely shown in FIG. 25, a gradient angle y of the cup 42 from a bottom inner wall of the stem at an inner side of the cup 42 is designed to be 22 degrees.
Since the gradient angle y of the cup 42 is small and the light reflected by the cup 42 is directed to the total reflection region 19 in this light emission source 41 , the light emitted from a side wall of the light emitter 12 and reflected by the cup 42 is totally reflected by the total reflection region 19 to be directed to the light reflecting portion 20 , and further reflected by the light reflecting portion 20 to pass through the total reflection region 19 for forward emission as shown in FIG. 24. The light striking against the direct emission region 18 among the light emitted from a front of the light emitter 12 becomes subject to a lens function on the direct emission region 18 , and is emitted forward.
Thus, the light reflected by the cup 42 is totally reflected by the total reflection region 19 to be directed to the light reflecting portion 20 , whereby the light path can be freely controlled by the light reflecting portion 20 . Accordingly, when the light reflected by the cup 42 employing lead frames 14 and 17 is directed to the total reflection region 19 , almost all light emitted from the light emitter 12 can be emitted to a desired direction (for example, a direction in parallel with the optical axis of the light emitter 12 ). In this embodiment, the light emission source 41 is free from becoming large.
The reason why the light path can be freely controlled by directing the light reflected by the cup 42 toward the total reflection region 19 will be explained hereinafter. Before the light emitted from a front and a side of the light emitter 12 reaches the light reflecting portion 20 , the light path is bent by the reflection at the total reflection region 19 , so that the light path length from the light emitter 12 to the light reflecting portion 20 becomes long, whereby the light reflecting portion 20 receives the light emitted from a front of the light emitter 12 and the light emitted from a side of the light emitter 12 and reflected by the cup 42 in approximately same directions respectively. Accordingly, they can be simultaneously controlled. When the curvature of the light reflecting portion 20 is designed, both are possible to be generally designed.
FIG. 29 is a sectional view of a light emission source 43 according to an eighteenth embodiment. This embodiment is of a can package type, in which a front wall of a light reflecting portion 20 is filled with a transparent mold resin 13 , a rear wall of the light reflecting portion 20 is filled with an insulating material 46 , a cylindrical housing 44 extending from outer circumferential portion of the light reflecting portion 20 covers an outer peripheral surface of the insulating material 46 , and a flange 45 is disposed at a periphery of a rear end of the housing 44 .
In addition, the light reflecting portion 20 in the center thereof is formed with the stem 15 as a single unit. Further, light reflecting portion 20 , stem 15 , lead frame 17 , cylindrical housing 44 and flange 45 are formed as a single unit by metallic material. A head of the lead frame 14 is inserted within an aperture 20 a of the light reflecting portion 20 without contact with the same.
Therefore, according to this embodiment, the number of parts is reduced, the assembly is easy, and manufacturing cost is reduced. In particular, it gets possible to produce it by a production process same as general can package products. Furthermore, the housing 44 and the flange 45 united with the stem 15 are exposed to a surface, whereby heat dissipation nature of the heat which is occurred with the light emitter 12 is improved, and the allowance forward current quantity is increased, thereby performing high brightness.
Furthermore, in this embodiment, the cup 42 disposed on the stem 15 is designed so that the light emitted from a side of the light emitter 12 and reflected by the cup 42 can be directed toward the total reflection region 19 , whereby each emission direction of the light emitted from the light emission source 43 can be aligned in one direction.
Several embodiments for a light receiver will be described hereinafter.
FIG. 30 is a perspective view of a light receiver 51 according to a nineteenth embodiment of this invention, and FIG. 31 is a sectional view of the receiver. According to this light receiver 51 , a photo detector 52 in a chip shape, such as a photo diode or photo-transistor or the like, and a light reflecting portion. 53 are sealed within a mold resin 54 made of a transparent resin material. The photo detector 52 sealed within the mold resin 54 is mounted on a stem 56 disposed on a head of a lead frame 5 , connected with another lead frame 58 by a bonding wire 57 , and disposed so that its light receiving wall faces forward.
In a front central part of the mold resin 54 , there is provided a direct incidence region 59 having a convex lens configuration such as a spherical lens shape, an aspherical lens shape, or a paraboloid shape. A flat region 60 (resin boundary surface) having flatness is formed to surround the direct incidence region 59 . The direct incidence region 59 is formed so that its medial axis may accord with an optical axis of the photo detector 52 . The flat region 60 has a flat face perpendicular to the optical axis of the photo detector 52 . The photo detector 52 is located at a focal point of the direct incidence region 59 or its neighborhood, and the light striking against the direct incidence region 59 in the light approximately perpendicularly striking against the photo detector is focused to the photo detector 52 to be received by its light receiving face.
An angle α of a direction, viewed from the photo detector 52 toward a boundary between the direct incidence region 59 and the flat region 60 , from the optical axis is equal to a critical angle θ c of the total reflection between the mold resin 54 and air or larger.
A light reflection portion 53 is a metal plate which is molded to a parabola shape by press working and plated with aluminum or silver on its surface for specular working. If desired, the light reflection portion 53 may employ a pressed part of aluminum or silver which is applied by chemical treatment for providing glossiness on its surface. The light reflecting portion 53 at its center is provided an aperture 61 for accommodating a stem 56 , and is sealed within a mold resin 54 together with lead frames 55 and 58 wherein the stem 56 mounted by the photo detector 52 is accommodated within the aperture 61 . A configuration of a section of the light reflecting portion 53 is designed so that the light perpendicularly striking against the flat region 60 of the mold resin 54 and reflected by the light reflecting portion 53 may be totally reflected by the flat region 60 to enter into the photo detector 52 .
Accordingly, the light striking against the direct incidence region 59 in the light approximately perpendicularly striking against the light receiver 51 is refracted to be focused on the photo detector 52 when it passes the direct incidence region 59 . The light striking against the flat region 60 is reflected by the light reflecting portion 53 , and totally reflected by the flat region 60 to be focused on the photo detector 52 . Thus, most of light approximately perpendicularly striking against the light receiver 51 can be focused on the photo detector 52 , whereby the light receiver 51 having a high efficiency of light receipt can be produced. The light requirement can be increased by increasing the light receive area which can be performed by enlarging the light reflecting portion 53 without depending on the area of the photo detector 52 , thereby increasing the light requirement and the light receiving efficiency at a reduced cost. Moreover, thinning the light receiver 51 can be performed by increasing the light receiving efficiency without thickening the receiver.
According to the light receiver 51 having such a configuration, the light reflecting portion 53 which is a discrete part together with the photo detector 52 and the stem 56 has only to be set within a molding metal mold, thereby simplifying the manufacturing process of the light receiver 51 .
The angle of a circumference face of the light reflecting portion 53 is adjusted to the angle portion of the mold resin 54 . Accordingly, when the mold resin 54 is molded, an outer circumferential angle on a reflection side of the light reflecting portion 53 coming into contact with an inner wall of a cavity of molding metal mold can be set, whereby the light reflecting portion 53 is fixed about its position to be precisely inserted within the mold resin 54 , thereby improving the mounting accuracy of the light reflecting portion 53 .
FIG. 32 is a sectional view of a light receiver 62 according to a twentieth embodiment. In this embodiment, a direct incidence region 59 is disposed at a center of a surface core of the mold resin 54 , a taper-shaped portion 63 in a circular cone (block) or pyramid (block) shape which hollows at its center is disposed around the direct incidence region 59 , and a flat region 60 is disposed outside the portion 63 . The medial axis of the taper-shaped part 63 agrees with an optical axis of a photo detector 52 , and the flat region 60 has a face perpendicular to a photo detector 52 .
According to this light receiver 62 , the incident light to the direct incidence region 59 is refracted to be directed to the photo detector 52 . The light almost perpendicularly striking the flat region 60 is reflected light reflecting portion 53 , and further totally reflected by the flat region 60 to be directed to the photo detector 52 . The taper-shaped portion 63 is designed so that the light entering through the flat region 60 to be reflected by an outer circumferential portion of the light reflecting portion 53 can be directed to the photo detector 52 without totally reflected in a direction deviating from the photo detector 52 when it is totally reflected near the direct incidence region 59 . According to this embodiment, the light receiving efficiency is improved. The employment of the taper-shaped part 63 allows the projection length of the direct incidence region 59 to be decreased and the light receiver 62 to be thinned.
According to thus construction, an angle a of a direction, viewed from the photo detector 52 toward a boundary between the direct incidence region 59 and of the taper-shaped part 63 , from the optical axis can be smaller than a critical angle θ c of the total reflection between the mold resin 54 and air.
FIG. 33 is a perspective view of a light receiver 64 according to a twenty-first embodiment, which is used as a solar cell. In this light receiver 64 (solar cell), a light reflecting portion 53 a longitudinally uniform section of which has a parabola-shape is sealed within mold resin 54 . In front of the light reflecting portion 53 , there is disposed a photo detector 52 (a photoelectric transducer such as a silicon system photoelectric transducer of amorphous, polycrystal or monocrystal). In the center of a front wall of the mold resin 54 there is disposed a direct incidence region 59 in a longitudinally cylindrical lens-shape, and a flat region 60 is formed at each side thereof.
The light striking against the direct incidence region 59 in the light perpendicularly striking against the light receiver 64 is directly focused on the photo detector 52 . The light striking against the flat region 60 is reflected by the light reflecting portion 53 , and further totally reflected by the flat region 60 to be received by the photo detector 52 . Since the photo detector 52 is long in one direction, the light receiving area can be increased, thereby performing large focused quantity and providing a high generating capacity as a solar cell.
Generally, the energy conversion efficiency of a conventional solar cell is only 15%. Accordingly, in order to increase the generating capacity, the area of the photoelectric transducer itself has to be increased with increasing manufacturing cost. According to the light receiver 64 (solar cell) of this invention, however, the light receiving area can be increased so as to efficiently focus the light striking against the light receiving area to the photo detector 52 by increasing the whole area of the light receiver 64 without increasing the area of the photoelectric transducer itself, thereby enhancing the generating capacity with an economy means. In particular, according to the configuration of this embodiment, the light focus efficiency can be increased two times or more, and the substantial energy conversion efficiency also can be increased two times or more.
Furthermore, according to this light receiver 64 , the efficiency can be enhanced with retaining the thin configuration, whereby a thin configuration can be applied to a solar panel put on a roof of a house, a road tack, or delineator.
In the light receiver 64 shown in FIG. 30 or 31 , a photoelectric transducer can be mounted as the photo detector 52 .
FIG. 34 is a perspective view of a light emission source 65 according to a twenty-second embodiment, FIG. 35 at (a) is a front view of the source, FIG. 35 at (b) is a sectional view taken along line X 1 -X 1 of FIG. 35 at (a), and FIG. 35 at (c) is a sectional view taken along line Y 1 -Y 1 of FIG. 35 at (a). In this embodiment, a light emitter 12 such as a light emitting diode (LED chip) is sealed in a mold resin 13 made of a transparent resin material. The light emitter 12 sealed in the mold resin 13 is mounted on a stem 15 disposed on a leading edge of a lead frame 17 , and connected with another lead frame 14 by means of a bonding wire 16 , and a light emission side thereof is disposed toward a front of the light emission source 65 .
A light reflecting portion 20 is composed of a metallic component which is molded in a parabola shape by press working, and its surface is applied by specular working of plating aluminum or silver thereon. If desired, the light reflecting portion 20 may be done by chemical processing applied to a pressed part made of aluminum or silver to bring glossiness on the surface thereof. The light reflecting portion 20 at a center thereof includes an aperture 20 a for accommodating the stem 15 , and is sealed with the lead frames 14 and 17 within the mold resin 13 where the aperture 20 a accommodates the stem mounted by the light emitter 12 .
As shown in FIG. 35 at (a), the light reflecting portion 20 has major and minor axis directions when it is viewed from its front, and a generally elliptic shape in this embodiment. An outer circumferential edge of the light reflecting portion 20 is formed to be in parallel with a front face of the mold resin 13 , whereby any large clearance does not occur between the outer circumferential edge of the light reflecting portion 20 and the front face of the mold resin 13 so that any light is prevented from leaking through the clearance and becoming loss.
The section in the major axis direction as shown in FIG. 35 at (b) and the section in the minor axis direction as shown in FIG. 35 at (c) are curved in a concave, but in different shapes. In other words, the distribution field of curvature of the section in the major axis direction is different from the distribution field of the section in the minor axis direction. The distribution field of curvature of the section in the major axis direction is shifted toward a smaller value than the distribution field of the section in the minor axis direction.
As long as the section of the light reflecting portion 20 is in an arc shape either in the major and minor axis directions, when a radius of a section in the major axis direction is R 1 and a radius of the section in the minor axis direction is Rs;
(1/ R 1)<(1/ Rs )
In other words, the radius R 1 in the major axis direction is larger than the radius Rs in the minor axis direction(R 1 >Rs).
When the section of the light reflecting portion 20 is not arc-shaped, the curvature varies with a location in the sections of the major and minor directions so that it has a spread (distribution). For instance, this case can be featured by a central value of a distribution of curvature. Assuming that the curvature in the major direction has the minimum value (ρl)min and the maximum value (ρ l)max and the curvature in the minor direction has the minimum value (ρ s)min and the maximum value (ρ s)max, the respective central values (ρ l)c and (ρ s) are expressed by the following equations;
Major axis direction: (ρ l ) c ={(ρ l )min+(ρ l )max}/2
Minor axis direction: (ρ s ) c ={(ρ s )min+(ρ] s )max}/2
Accordingly, in the light reflecting member 20 employed in the light emission source 65 according to this invention, the central value (ρ l)c of the curvature in the section in the major axis direction has only to be smaller than the central value (ρ s) of the curvature in the section in the minor axis direction as expressed by the following equation;
(ρ l ) c <(ρ s ) c
If desired, both ends of the distribution of curvatures are featured by the minimum and maximum values, and the following equation may be made;
(ρ l )min≦(ρ s )min
(ρ l )max≦(ρ s )max
provided that this equal sign does not happen simultaneously.
In a front central portion of the mold resin 13 , there are formed a direct emission region 18 in a convex lens shape, and a total reflection region 19 of a flat shape to surround the direct emission region 18 . The direct emission region 18 is formed so that its optical axis accords with the optical axis of the light emitter 12 , and the total reflection region 19 is a plane perpendicular to the optical axis of the light emitter 12 . The light emitter 12 is located in a focal point of the direct emission region 18 or in its neighborhood. The angle of a direction against the optical axis, viewed from the light emitter 12 toward a boundary between the direct emission region 18 and the total reflection region 19 , is designed to be equal to the critical angle θ c of the total reflection between the mold resin 13 and air, or larger.
When the direct emission region 18 having a lens shape is viewed from its front, it has a generally ellipse shape having a major axis direction and a minor axis direction, and the respective major and minor axis directions accord with the major and minor axis directions of the light reflecting portion 20 . In the direct emission region 18 , the distribution field of curvature of a section in a major axis direction is different from the distribution field of curvature of a section in a minor axis direction, and, particularly, the curvature distribution of the section in the major axis direction is shifted to a side of a smaller value than the curvature distribution of the section in the minor direction. Shifting the curvature distribution of the section in the major axis direction to the side of the smaller value than the curvature distribution of the section in the minor direction has same meaning as that of the light reflecting portion 20 .
The light radiated to the direct emission region 18 in the light emitted from the light emitter 12 is directly emitted forward from a front of the mold resin 13 as an approximately paralleled light. The light emitted to the total reflection region 19 in the light emitted from the light emitter 12 is totally reflected by a resin boundary surface, and almost of the totally reflected light by the resin boundary surface is reflected by the light reflecting portion 20 to be emitted forward from the total reflection region 19 . Thus, almost all light emitted forwardly from the light emitter 12 (viz. including the light totally reflected by the total reflection region 19 ) can be brought into a front of the light emission source 65 , thereby improving the efficiency of light use. Moreover, the light emitted forward from the light emitter 12 is emitted from the direct emission region 18 without any obstruction, whereby darkness on the optical axis as found in the above-described conventional light emission source is avoided and the directive pattern is improved.
Furthermore, the light emitted from the light emitter 12 in a diagonal direction is totally reflected by the total reflection region 19 , and reflected by the light reflecting portion 20 to be emitted forward so as to prolong the light length becomes long, whereby the aberration is reduced and the light emission source 65 can be provided with a high accuracy.
The light reflecting portion 20 has a generally ellipse configuration, whereby the light reflected by the light reflecting portion 20 to be emitted forward becomes beams having an emission profile in a generally elliptic shape as shown in FIG. 36. The direct emission region 18 also has a generally elliptic shape a major axis direction of which accords with the major axis direction of the light reflecting portion 20 , so that the light beams emitted from the direct emission region 18 have a section in a generally elliptic shape. Accordingly, as shown in FIG. 37, the light emitted from the direct emission region 18 supplements the light emitted from the total reflection region 19 , so that combination of the light emitted from the direct emission region 18 and the light emitted from the total reflection region 19 provides emission light having an approximately uniform intensity elliptic profile.
When, in order to emit light in a generally elliptic shape spreading in one direction, a hemisphere-shaped metal member having a constant curvature in an optional direction is prepared and both sides of the metal member are cut to provide a light reflecting portion which is lengthened longitudinally, there appears a large clearance between the cut portion and a front face of the mold resin through which light leaks, thereby deteriorating the efficiency of light use. Such a clearance can be reduced by having a curvature varying with directions, thereby enhancing brightness of the light emission source 65 . When the curvatures in orthogonal two directions in the light reflecting portion 20 having a circle in its front view are different, the spread of the reflection light can be different, thereby providing emission light of a generally elliptic profile spreading in one direction. When the light reflecting portion 20 has an elliptic shape, the design of the light reflecting portion 20 becomes easy.
The light reflecting portion 20 can be realized by employing an aspherical surface of a toric surface or a biconical surface, and a more uniform beam profile can be designed. FIG. 38 at (a) shows a light reflecting portion 20 formed with a biconical surface. When the light reflecting portion 20 has an X axis in a major axis direction, a Y axis in a minor axis direction, and a Z axis in a front direction, the light reflecting surface of the light reflection portion 20 having the biconical surface can be expressed by the following equation (1);
When a sectional configuration in a XZ plane of the biconical surface is expressed by “Z=g1(X)”, a curvature of the curve is expressed by “cv”, the conic coefficient is expressed by “cc”, and a sectional configuration in a YZ plane is expressed by “Z=g2(Y)”, the curvature of this curve becomes “cvx(≠cv)”, and t