05/060048

07/25/1972

07/31/1970

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International Business Machines Corporation (Armonk, NY)

345/686

345/25

G09G5/34; G09G5/42; G06F3/14

340/324A

3439218	CONTROL CIRCUIT FOR CAUSING MOVEMENT OF A CATHODE RAY TUBE DISPLAY	April 1969	Savinese et al.
3540012	CRT DISPLAY EDITING CIRCUIT	November 1970	Ehrman

Trafton, David L.

What is claimed is

1. In a television type display device which receives video information from a cyclical storage device, the method of scrolling up or down which comprises the steps of:

2. storing a home position character at any storage location in the cyclical storage device,

3. initiating a new frame whenever the home position character is detected, and

4. moving the home position character to different storage locations to scroll up or down.

5. The method of claim 1 further including the step of inserting new data in the storage location vacated by the home position character.

6. In a television type display device which generates and displays on a cathode ray tube successive frames of video information which video information is supplied by a cyclical storage device, the method of scrolling up or down which comprises the steps of:

7. Storing a home position character in any storage location in the cyclical storage device,

8. initiating a new frame in the cathode ray tube commencing from a given position on the face of the cathode ray tube whenever the home position character is detected in the cyclical storage device, and

9. moving the home position character to different storage locations in the cyclical storage device to scroll up or down.

10. The method of claim 1 further including the step of inserting new data in the cyclical storage device in the storage location vacated by the home position character when new information is to be displayed.

11. In a television type display device which displays on the face of a cathode ray tube successive frames of video information supplied by a cyclical storage device, the method of scrolling up or down on the face of the cathode ray tube which comprises the steps of:

12. storing a home position character in any storage location in the cyclical storage device,

13. detecting the home position character and initiating a new frame when-ever the home position character is detected, and

14. moving the home position character successively to different storage locations in the cyclical storage device thereby to initiate new frames and scroll up or down on the face of the cathode ray tube.

15. The method of claim 1 further including the step of inserting new data in the storage locations vacated by the home position character.

16. A method of scrolling information on the face of a television type display device which generates successive frames from video information supplied by a cyclical storage device, said method including the steps of:

17. generating a raster on the face of the cathode ray tube commencing from a given point on the face of the cathode ray tube,

18. using video information signals to modulate the electron beam of the cathode ray tube thereby to generate a visual display,

19. positioning a raster reset command in a selected storage location within the video information stored in the cyclical storage device, and

20. detecting the presence of the raster reset command and initiating the generation of a new raster commencing at said given point when the raster reset command is detected,

21. changing the location of the raster reset command in said cyclical storage device to scroll up or down on the face of the cathode ray tube.

22. The method of claim 7 further including the step of inserting new data in the cyclical storage device at the storage location vacated by the raster reset command.

23. A method of scrolling information on the face of a cathode tube where successive frames are generated on the face of the cathode ray tube and video information from storage location in a cyclical storage device is repetitively displayed during each frame, the method comprising the steps of:

24. generating successive frames on the face of the cathode ray tube,

25. displaying video information from a cyclical storage device during each frame, and

26. selectively changing the cycle of the frames generated on the face of the cathode ray tube to commence at any storage location in the cyclical storage device.

27. The method of claim 9 wherein the last step includes storing a home position character in the cyclical storage device and selectively moving it to different storage locations in the cyclical storage device thereby to initiate the generation of new frame cycles commencing from a given point on the face of the cathode ray tube each time the home position character is moved.

28. The apparatus of claim 10 including the further step of inserting new video data in the storage location of the cyclical storage device vacated by the home position character.

BACKGROUND OF THE INVENTION

1. This invention relates to a method for scrolling and more particularly to a method for scrolling information on the face of a cathode ray tube of a television type display device.

2. In earlier types of television type display devices successive frames are generated to present a visual display on the face of the cathode ray tube, and video information from a cyclical storage device is supplied to the cathode ray tube during each frame. Scrolling information on the face of the cathode ray tube involves moving the information up or down on the face of the cathode ray tube. The scrolling technique heretofore involves placing the video information in a given order or format in the cyclical storage device, synchronizing the cycle of the storage device with the cycle of the frames generated on the face of the cathode ray tube, and scrolling by reorienting or rearranging the order or format of all of the video information in the cyclical storage device. Such scrolling operations entail terminating the display for the duration of the time required to reorient or rearrange the video information in the cyclical storage device, or providing additional buffer storage for the purpose of reorienting the order or format of the video information prior to the time it is needed. Such disadvantages are eliminated by the novel techniques of the present invention.

SUMMARY OF THE INVENTION

It is a feature of this invention to provide a novel method for scrolling information up or down display on the face of a cathode ray tube.

It is a feature of this invention to provide an improved method for scrolling information up or down on the face of a cathode ray tube which may be employed in all types of television type display apparatus.

In the novel method according to this invention information is scrolled up or down on the face of a cathode ray tube where successive frames are generated on the face of the cathode ray tube, and video information from storage locations in a cyclical storage device is repetitively displayed during each frame. The method comprises the steps of generating successive frames on the face of the cathode ray tube, displaying video information from a cyclical storage device during each frame, and selectively changing the cycle of the frames generated on the face of the cathode ray tube to commence at any storage location in the cyclical storage device. This novel technique eliminates the disadvantages discussed above with respect to scrolling techniques heretofore employed because video data in the cyclical storage device is not reoriented. Some modification of the data in the storage device takes place, but this can be done with little or no loss of time. In a preferred form of the method according to this invention a television type display device receives video information from a cyclical storage device, and the method of scrolling up or down includes the steps of storing a home position character in any storage location in the cyclical storage device, initiating a new frame in the cathode ray tube commencing from a given position on the face of the cathode ray tube whenever the home position character is detected in the cyclical storage device, and moving the home position character to different storage locations in the cyclical storage device thereby to scroll by moving information up or down. This novel method may include the further step of inserting a new video data in the cyclical storage device in the storage location vacated by the home position character when new information is to be displayed. When the home position character is shifted from a first storage location to a second storage location in the cyclical storage device, the video data previously stored in the second storage location is destroyed. This novel technique may be employed to scroll information up or down in all types of existing television type display devices which repetitively generate frames on the face of a cathode ray tube and display video information supplied by a cyclical storage device.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred method of the invention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a television type display device.

FIGS. 2 through 4 illustrate scrolling of information displayed on the face of a cathode ray tube.

FIGS. 5 through 7 illustrate different storage formats of video information in a cyclical storage device for scrolling operations according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The novel method according to this invention may be employed in all types of television type display arrangements which generate a raster on the face of a cathode ray tube and display successive frames of video information repetitively supplied by a storage device, preferably a cyclical storage device. The novel method according to this invention is described hereinafter with respect to particular apparatus. It is to be understood, however, that the method has general application, and the particular apparatus is used by way of illustration and not limitation.

Referring first to FIG. 1, one illustrative arrangement is shown which includes a cathode ray tube 10 with a pair of vertical deflection plates 11, 12 and a pair of horizontal deflection plates 13, 14. A control grid 15 regulates the intensity of an electron beam supplied by an electron gun 16. A vertical deflection circuit 30 supplies deflection potentials to the vertical plates 11 and 12, and the vertical sweep circuit 30 is reset by a signal on an input line 31. The electron beam is moved to the top of the face of the cathode ray tube 10 when a reset signal is applied on the line 31 to the vertical sweep circuit 30. A horizontal sweep circuit 32 supplies deflection potentials to the horizontal deflection plates 13 and 14, and the horizontal sweep circuit 32 is reset by a signal on an input line 33. The electron beam is moved to the left on the face of the cathode ray tube when a reset signal is applied on the line 33 to the horizontal sweep circuit 32. An intensity control 34 supplies signals to the control grid 15. The electron beam is blanked or unblanked in response to control signals supplied on an input line 35. The electron beam is customarily blanked during flyback at the end of each horizontal sweep as well as during the flyback between frames.

A data store 50 supplies video signals to the intensity control 34 for the purpose of modulating the control grid 15 to generate a visible display on the face of the cathode ray tube 10. A data input register 51 supplies new data to be written into the data store 50. An address register 52 designates the storage location in the data store 50 where new data is stored. The data store 50 may be any one of many well known types of storage devices. A cyclical storage device is preferred, and endless storage devices such as storage drums, endless belts or tapes, and delay lines are suitable for instance.

Scrolling of the visual presentation on the face of a cathode ray tube may take place upwardly or downwardly in the novel method according to this invention. If a text is displayed, for example, it may be scrolled up one line at a time, or it may be scrolled down one line at a time. The rate at which scrolling takes place may be increased or diminished as desired, and scrolling of a text may take place up or down two or more lines at a time where this is preferred.

The novel method for scrolling up or down according to this invention is described in detail with reference to FIGS. 2 through 7. Let it be assumed for purposes of illustration that a message in a form of a text is to be displayed on the face of the cathode ray tube 10, and let it be assumed further that the message text to be illustrated and scrolled is the text shown in FIG. 2. The text in character lines 1 through 6 in FIG. 2 are initially displayed. The text shown in lines 7 and 8 is to be displayed subsequently. A dot 60 in FIGS. 2 through 4 designates the home position is the point from which the electron beam starts each frame. The electron beam is directed toward the home position when the vertical sweep circuit 30 in FIG. 1 and the horizontal sweep circuit 32 are reset. When a frame commences, the vertical sweep circuit 30 in FIG. 1 and the horizontal sweep circuit 32 generate a raster over the face of the cathode ray tube 10, and the video signals supplied to the intensity control 34 vary the signal level on the grid 15 to modulate the intensity of the electron beam. This modulation during one raster defines a frame. Frames of the same information are repetitively generated as long as a given visual presentation is to be viewed.

FIG. 2 illustrates character lines 1 through 8. The character lines 1 through 6 are to be displayed initially, and as scrolling takes place the character lines 7 and 8 are to be scrolled into view as the respective upper character lines 1 and 2 move off of the face of the cathode ray tube 10. It is pointed out that the character lines 1 through 8 each require a plurality of horizontal sweeps of the cathode ray tube 10 in FIG. 1. FIG. 5 depicts an endless store such as a delay line where the output is connected back to the input thereof. Video signals for the various character lines are stored in the segments of the delay line as depicted in FIG. 5. The letters A through G in FIG. 5 designate storage locations in the delay line. Storage location A in FIG, 5 stores the home position character, and this character is employed to dictate when the electron beam is to be returned to the home position 60 in FIG. 2. It serves as a frame reset command in essence. The electron beam is positioned to the home position by applying reset signals to the lines 31 and 33 in FIG. 1. These signals operate the associated vertical sweep through circuit 30 and the horizontal sweep circuit 32 to position the electron beam to the home position 60. Whenever the electron beam is being returned to the home position, a signal is applied to the line 35 in FIG. 1 which operates the intensity control 34 to apply a signal to the grid 15 which blanks the electron beam. When the home position character in FIG. 5 terminates, the generation of a frame commences. More specifically, the video data in storage location B is displayed as line 1 in FIG. 2. As the video information is read from successive storage locations C through G, character lines 2 through 6 in FIG. 2 are displayed in the positions shown. Storage locations B through G are shown in FIG. 2 to the left of the associated character lines. As soon as the video information in storage location G of FIG. 5 has been read and displayed, the home position character in storage location A is read, and as a consequence the electron beam is blanked and returned to the home position 60 in FIG. 2. Upon termination of the reading of the home position character from storage location A in FIG. 5, another frame of the same information is generated. This process is repeated as long as it is desired to view the information shown on the face of the cathode ray tube 10 in FIG. 2.

The address register 52 in FIG. 1 stores the address of the home position character, and the data input register 51 stores new information to be displayed when upward scrolling is to take place. To scroll, the new information in the data input register 51 is written at the address indicated by the address register 52. More specifically, the video information for character line 7 in FIG. 2 is stored in storage location A thereby destroying the home position character. As soon as this operation has been completed, the address register 52 is advanced to indicate storage location B, and the home position character is inserted in the data input register 51 and stored in this location of the data store 50. This changes the storage format from that indicated in FIG. 5 to that shown in FIG. 6. It is pointed out that the home position character commences immediately after line 6 in FIG. 5 is read and displayed, and the home position character continues throughout the time period represented by storage locations A and B in FIG. 6 because of the writing operations. The electron beam is blanked, and it is directed toward the home position 60 in FIG. 2 throughout this time period. A new raster is generated, and character line 2 in FIG. 6 is displayed as the top character line. This is illustrated in FIG. 3. As successive storage locations C through G and A in FIG. 6 are read and displayed during this frame, successive character lines 2 through 7 of FIG. 6 are displayed on the face of the cathode ray tube 10 as Illustrated in FIG. 3. When the home position character in storage location B is read, the electron beam is blanked and returned to the home position 60 in FIG. 3. As the storage format in FIG. 6 is continuously read and displayed in successive frames, the information shown in FIG. 3 is constantly displayed as long as desired.

When it is desired to scroll again, new data is placed in the data input register 51 in FIG. 1 and written in the location of the data store 50 indicated by the address register 52. The address register 52 first is incremented to indicate storage location C, and the home position character is stored in that location. The home position character is presented to the intensity control circuit 34 during the time period covered by the storage locations B and C. This blanks the electron beam and returns it to the home position 60. Upon completion of the writing operation, the video data for character line 8 is stored in storage location B, and the home position character is stored in storage location C as illustrated in FIG. 7. A new frame is generated with character line 3 displayed at the top of the face of the cathode ray tube 10 as illustrated in FIG. 4. As successive storage locations D through G, A, and B in FIG. 7 are read and displayed, successive character lines 3 through 8 are displayed on the face of the cathode ray tube 10 in the manner illustrated in FIG. 4. As the storage format in FIG. 7 is repetitively read and displayed in successive frames, the text in FIG. 4 is displayed on the face of the cathode ray tube 10. Successive scrolling operations may take place in the manner explained until all information to be presented, including further information not shown, has been displayed on the face of the cathode ray tube 10.

It is seen, therefore, that scrolling upwardly is accomplished according to the novel method of this invention by shifting the home position character successively to the right through respective storage locations A, B, and C as shown in respective FIGS. 5 through 7. As the home position character is shifted one position to the right, its former location is filled with new information. This new information is displayed in each instance in the bottom character line on the face of the cathode ray tube 10.

If it is desired to reverse the direction of scrolling from an upward direction to a downward direction, then the home position character is shifted to the left, and new information is inserted in the storage location formerly occupied by the home position character. To illustrate, if the home position character is in storage location C as shown in FIG. 7 when a scrolling down operation is to take place, the home position character is written in storage location B, and new video information is written in storage location C. This is accomplished by inserting the home position character in the data input register 51 in FIG. 1 and changing the address register 52 to indicate storage location B. When storage location B arrives, the home position character is written. New video data is inserted in the data input register 51 and written in storage location C which is then available for a writing operation in a cyclical storage device. The video information for character line 2 thereby is placed in storage location C. The resulting storage format is that illustrated in FIG. 6. This storage format generates and displays the text shown in FIG. 3. Thus it is seen how a downward scrolling operation is performed.

If another downward scrolling operation is to take place, the home position character in FIG. 6 is moved to the left to the position indicated in FIG. 5, and video information representing character line 1 is stored in storage location B. The resulting storage format is shown in FIG. 5. The storage format in FIG. 5 generates the message next shown on the face of the cathode ray tube 10 in FIG. 2.

It is readily seen by observation from FIGS. 5 through 7, in view of the foregoing explanation, that scrolling operations up or down may take place by shifting the home position character respectively to the right or left in succession and placing new data in the storage location vacated by the home position character. This orients the stored video data to lie in the proper storage locations whereby the home position character initiates each frame to synchronize the television type cathode ray tube display device with the cyclical storage device. This novel method of initiating a frame at any point in the cycle of a cyclical storage device permits scrolling to take place either upwardly or downwardly as desired without rearranging all of the video data stored in the cyclical storage device. The home position character may be selectively changed from any storage location to any other storage location in the cyclical storage device for scrolling purposes. If it is desired to scroll two or more lines at a time, this may be accomplished by shifting the home position character by two or more storage locations to the right or left. New video data is placed in the storage location vacated by the home position character and the intervening skipped storage locations. The rate of scrolling is controlled by the rate at which the hOme position character is shifted from one storage location to another.

While the invention has been particularly shown and described with reference to a preferred embodiment thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the spirit and scope of the invention.