Display system for selectively overlaying symbols and graphics onto a video signal

• US 5,579,057 A
• Filed: 01/05/1995
• Issued: 11/26/1996
• Est. Priority Date: 06/07/1993
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Scientific-Atlanta Incorporated (Cisco Systems, Inc.)
• Inventors: Ith, Cham, Burleson, David B., Banker, Robert O., Bacon, Kinney C.
• Primary Examiner(s): Kostak, Victor R.
• Assistant Examiner(s): Flynn, Nathan J.
• Application Number:
  US08/369,867
• Time in Patent Office: 691 Days
• Field of Search: 345/194, 345/195, 345/26, 345/187-189, 345/192, 345/23, 348/589, 348/569, 348/600, 348/586, 348/10, 348/12, 348/13, 348/7, 395/147
• US Class Current: 348/589
• CPC Class Codes: G09G 2340/12 Overlay of images, i.e. displayed pixel being the result of switching between the corresponding input pixels
• CPC Class Codes: H04N 21/2743 Video hosting of uploaded data from client
• CPC Class Codes: H04N 21/4112 having fewer capabilities than the client, e.g. thin client having less processing power or no tuning capabilities
• CPC Class Codes: H04N 21/4316 for displaying supplemental content in a region of the screen, e.g. an advertisement in a separate window
• CPC Class Codes: H04N 21/47 End-user applications
• CPC Class Codes: H04N 21/4786 e-mailing message switching systems, e.g. electronic mail systems H04L51/00
• CPC Class Codes: H04N 21/4788 communicating with other users, e.g. chatting arrangements for providing for computer conferences, e.g. chat rooms, to substation in data switching networks H04L12/1813; distributed application using peer-to-peer [P2P] networks H04L67/104
• CPC Class Codes: H04N 21/488 Data services, e.g. news ticker systems specially adapted for using meteorological information in broadcast systems H04H60/71
• CPC Class Codes: H04N 21/4884 for displaying subtitles
• CPC Class Codes: H04N 21/6547 comprising parameters, e.g. for client setup
• CPC Class Codes: H04N 5/272 Means for inserting a foreground image in a background image, i.e. inlay, outlay
• CPC Class Codes: H04N 5/44504 Circuit details of the additional information generator, e.g. details of the character or graphics signal generator, overlay mixing circuits
• CPC Class Codes: H04N 5/45 Picture in picture , e.g. displaying simultaneously another television channel in a region of the screen
• CPC Class Codes: H04N 7/088 the inserted signal being digital
• CPC Class Codes: H04N 7/16 Analogue secrecy systems; Analogue subscription systems
• CPC Class Codes: H04N 7/161 Constructional details of the subscriber equipment H04N7/164 takes precedence

Abstract

A display system for the on screen display of information for a subscriber terminal of a subscription television system includes a display processor which can display information in the form of a display screen stored in a display memory. The display processor can be preprogrammed by the control processor with a plurality of display attributes including different symbol sets, different color palettes, whether the screen is to be a text screen, graphic screen or a combination of a text and graphics system, and the size and location of each screen display on the display area. The display processor includes a digital processor and an analog processor. The digital processor controls accessing the display data from the memory and converting it into timed digital pixels. The analog processor includes a digital to analog pixel converter which produces analog pixels from the digital pixels in a timed relation to an input video signal. The analog processor includes a multiplexer which substitutes the analog pixels for the pixels of the input video signal when display processor is active.

Claims

1. A display system of a subscriber terminal for use in a subscription television system, said subscriber terminal cormected to a television receiver which displays the programming of the subscription television system, said display system comprising:

a memory having a first graphics screen definition portion for storing graphics data, a second symbol screen definition portion and a third symbol set definition portion, the second and third portions for storing symbol data;

a display processor for generating a fast video signal according to said symbol data and said graphics data stored in said memory; and

a display multiplexer for receiving a second video signal, said second video signal originating remote from the subscriber terminal, for receiving said first video signal outputted from said display processor, and for selectively outputting a pixel of one of said first video signal and said second video signal for display on the television receiver.

2. A display system as set forth in claim 1 wherein;

said third symbol set definition portion of said memory contains more than one symbol set definition.

3. A display system as set forth in claim 2 wherein:

each symbol set definition has a plurality of characters, each defined by an m×

n array of pixels, where m and n are integers.

4. A display system as set forth in claim 3 wherein:

at least one of the parameters n and m for one symbol set definition is not the same as n and m for at least one other symbol set definition.

5. A display system as set forth in claim 2 wherein:

at least one of said character set definitions has a plurality of characters defining a different language from at least one other character set.

6. A display system as set forth in claim 5 wherein:

at least one of said character set definition is English.

7. A display system as set forth in claim 5 wherein:

at least one of said character set definitions is Chinese.

8. A display system as set forth in claim 5 wherein:

at least one of said character set definitions is Arabic.

9. A display system as set forth in claim 5 wherein:

at least one of said character set definitions is Japanese.

10. A display system as set forth in claim 1 wherein:

said memory is random access memory.

11. A display system as set forth in claim 10 wherein:

said random access memory is read/write memory.

12. A display system for generating a first video signal comprising:

a memory having a first graphics screen definition portion for storing graphics data, a second symbol screen definition portion and a third symbol set definition portion, said second and third portions for storing symbol data;

display generating means for converting said symbol data and graphics data stored in said memory to pixel data;

display processing means, responsive to said display generating means, for converting said pixel data to an analog pixel signal; and

display multiplexing means for generating said first video signal by multiplexing between said analog pixel signal and a second video signal on a pixel by pixel basis, said second video signal originating remote from the subscriber terminal.

13. The display system according to claim 12, said symbol data including a plurality of character sets, each of said character sets defining a plurality of characters, wherein each of said characters is defined by an m by n array of pixels.

14. The display system according to claim 13, one of said character sets being an English character set.

15. The display system according to claim 13, one of said character sets being a Chinese character set.

16. The display system according to claim 13, one of said character sets being an Arabic character set.

17. The display system according to claim 13, one of said character sets being a Japanese character set.

18. The display system according to claim 12, said display system being a subsystem of a subscriber terminal of a cable television system.

19. The display system according to claim 12 further comprising control processing means for controlling operation of said display generating means.

20. The display system according to claim 12, said display generating means converting one of said symbol data and said graphics data to said pixel data according to priority data.

21. The display system according to claim 12, said display processing means having pixel conversion means for converting said pixel data to said analog pixel signal, and said display multiplexing means having analog multiplexing means, responsive to said display generating means, for multiplexing between said analog pixel signal and said second video signal.

22. The display system according to claim 21, said pixel data including luminance data and chrominance data, and said pixel conversion means including first digital to analog converter means for converting said luminance data to a luminance signal having a representative DC voltage level, second digital to analog converter means for converting said chrominance data to a sinusoidal chrominance signal having a representative color phase, and analog summation circuit means for summing said luminance signal with said chrominance signal to form said analog pixel signal.

23. The display system according to claim 12 further comprising a clock generation circuit means for generating a pixel clock signal having a plurality of cycles, wherein each cycle of said pixel clock signal represents a single pixel.

24. The display system according to claim 23, said clock generation circuit synchronizes said pixel clock signal with a horizontal synchronization pulse of said second video signal.

25. The display system according to claim 24, said clock generation circuit synchronizing said pixel clock signal with said horizontal synchronization pulse of said second video signal using a synchronization slicer circuit and a phase-lock loop circuit.

26. The display system according to claim 23, said display generating means having:

synchronization circuit means for generating a first horizontal synchronization signal, a vertical synchronization signal, a pixel number signal, and a line number signal in accordance with said pixel clock signal, and for generating a video mode signal that defines a sync tip timing, a color burst timing, a horizontal blanking timing, and a vertical blanking timing in accordance with said first horizontal synchronization signal, said vertical synchronization signal, said pixel number signal, and said line number signal; and

pixel generation circuit means for receiving said video mode signal from said synchronization circuit means and for converting said symbol data and said graphics data to said pixal data according to said video mode signl.

27. The display system according to claim 26 further comprising means for synthesizing a second horizontal synchronization signal synchronized with a horizontal synchronization pulse of said second video signal, wherein said synchronization circuit means synchronizes said first horizontal synchronization signal, said vertical synchronization signal, said pixel number signal, and said line number signal with said second horizontal synchronization signal.

28. The display system according to claim 26, said synchronization circuit means having a pixel counter and a horizontal line counter.

29. The display system according to claim 26, said pixel generation circuit means having means for detecting when said pixel data represents a transparent color and for controlling said video processing means to select said second video signal when said pixel data representing said transparent color is detected.

30. The display system according to claim 26 further comprising a memory interface circuit and address generation circuit that operate cooperatively to supply said symbol data and graphics data to said pixel generation circuit means.

31. The display system according to claim 19, said display generating means having a control interface circuit means for providing said control processing means access to configuration registers.

32. A method for use in a display system for generating a first video signal, the display system having a memory with a first graphics screen definition portion for storing graphics data, a second symbol screen definition portion and a third symbol set definition portion, the second and third portions for storing symbol data, said method comprising the steps of:

converting one of said symbol data stored in said second and third portions of said memory and said graphics data stored in said first portion of said memory to pixel data;

converting said pixel data to an analog pixel signal; and

generating said first video signal by multiplexing between said analog pixel signal and a second video signal on a pixel by pixel basis, said second video signal originating remote from the subscriber terminal.

33. The method for use in a display system according to claim 32, said symbol data including a plurality of character sets, each of said character sets defining a plurality of characters, wherein each of said characters is defined by an m by n array of pixels.

34. The method for use in a display system according to claim 33, one of said character sets being an English character set.

35. The method for use in a display system according to claim 33, one of said character sets being a Chinese character set.

36. The method for use in a display system according to claim 33, one of said character sets being an Arabic character set.

37. The method for use in a display system according to claim 33, one of said character sets being a Japanese character set.

38. The method for use in a display system according to claim 32, said display system being a subsystem of a subscriber terminal of a cable television system.

39. The method for use in a display system according to claim 32, said converting of one of said symbol data and said graphics data to said pixel data is performed according to priority data.