Method and apparatus for operating a display monitor

• US 4,677,430 A
• Filed: 08/23/1984
• Issued: 06/30/1987
• Est. Priority Date: 08/23/1984
• Status: Expired due to Term

• Current Assignee: Bell Telephone Laboratories, Inc. (Nokia Corporation)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.), AT&T, Inc.
• Inventors: Varvaro, Charles, Falkman, Richard J.
• Primary Examiner(s): NOT, DEFINED
• Application Number:
  US06/643,635
• Time in Patent Office: 1,041 Days
• Field of Search: 358/220, 340/724, 340/726, 340/749
• US Class Current: 345/682
• CPC Class Codes: G09G 1/00 Control arrangements or circuits, of interest only in connection with cathode-ray tube indicators; General aspects or details, e.g. selection emphasis on particular characters, dashed line or dotted line generation; Preprocessing of datacathode-ray oscilloscopes G01R13/20; radar display arrangements G01S7/04; display of digital non-picture data in television systems H04N7/0255
• CPC Class Codes: H04N 3/20 Prevention of damage to cathode-ray tubes in the event of failure of scanning

Abstract

A method and an apparatus for operating a display monitor to prevent burn-in of the screen. The entire display is imperceptibly moved in both vertical and horizontal directions by changing the temporal relationship between the information signal transmitted to the monitor and the signals used to synchronize the scanning of the screen.

Claims

1. A method of operating a monitor that displays information on a screen comprising

transmitting an information signal to said monitor representing information to be displayed on said screen,

transmitting a synchronizing signal to said monitor to synchronize scanning of said screen,

generating digital words each defining a single discrete change in the temporal relationship of said information signal and said synchronizing signal and

during the continued transmission of said information and synchronizing signals, responding to each of said generated digital words by effecting the discrete change in the temporal relationship of said information and synchronizing signals defined by said each generated digital word to effect a discrete displacement of the information displayed on said screen to prevent burn-in of said screen.

2. A method in accordance with claim 1 wherein said generating step comprises

generating digital words each defining a single discrete delay of said synchronizing signal with respect to said information signal.

3. A method in accordance with claim 2 wherein said step of generating digital words each defining a single discrete delay of said synchronizing signal with respect to said information signal comprises

generating one sequence of digital words defining an increasing sequence of discrete delays of said synchronizing signal with respect to said information signal from a minimum delay to a maximum delay.

4. A method in accordance with claim 3 wherein said step of generating digital words each defining a single discrete delay of said synchronizing signal with respect to said information signal further comprises

generating another sequence of digital words defining a decreasing sequence of discrete delays of said synchronizing signal with respect to said information signal from said maximum delay to said minimum delay.

5. A method in accordance with claim 4 wherein said step of generating digital words each defining a single discrete delay of said synchronizing signal with respect to said information signal further comprises

alternately repeating said generating one sequence step and said generating another sequence step.

6. A mthod in accordance with claim 2 wherein said step of generating digital words each defining a single discrete delay of said synchronizing signal with respect to said information signal comprises

generating a sequence of digital words defining a decreasing sequence of discrete delays of said synchronizing signal with respect to said information signal from a maximum delay to a minimum delay.

7. A method of operating a monitor that displays information on a screen to prevent burn-in of said screen comprising

transmitting an information signal to said monitor representing information to be displayed on said screen,

transmitting a horizontal synchronizing signal to said monitor to synchronize scanning of said screen,

transmitting a vertical synchronizing signal to said monitor to synchronize vertical scanning of said screen,

generating first digital words each defining a signal discrete change in the temporal relationship of said information signal and said horizontal synchronizing signal,

generating second digital words each defining a single discrete change in the temporal relationship of said information signal and said vertical synchronizing signal

during the continued transmission of said information and synchronizing signals, responding to each of said generated first digital words by effecting the discrete change in the temporal relationship of said information signal and said horizontal synchronizing signal defined by said each generated first digital word to effect a discrete horizontal displacement of the information displayed on said screen and

during the continued transmission of said information and synchronizing signals, responding to each of said generated second digital words by effecting the discrete change in the temporal relationship of said information signal and said vertical synchronizing signal defined by said each generated second digital word to effect a discrete vertical displacement of the information displayed on said screen.

8. Apparatus for operating a monitor that displays information on a screen comprising

means for transmitting an information signal to said monitor representing information to be displayed on said screen,

means for transmitting a synchronizing signal to said monitor to synchronize scanning of said screen,

means for generating digital words each defining a single discrete change in the temporal relationship of said information signal and said synchronizing signal and

means operative during the continued transmission of said information and synchronizing signals and responsive to each of said generated digital words for effecting the discrete change in the temporal relationship of said information and synchronizing signals defined by said each generated digital word to effect a discrete displacement of the information displayed on said screen to prevent burn-in of said screen.

9. Apparatus in accordance with claim 8 wherein said generating means comprises

means for generating digital words each defining a single discrete delay of said synchronizing signal with respect to said information signal.

10. Display apparatus comprising

a monitor having a screen for displaying information thereon,

means for transmitting an information signal to said monitor representing information to be displayed on said screen,

means for generating a blanking signal in fixed temporal relation to said information signal to define time intervals between distinct portions of said information signal, each said portion representing information to be displayed on a separate line on said screen,

means for generating a synchronizing signal by delaying said blanking signal by a variable delay time, where said variable delay time may be zero,

means for transmitting said synchronizing signal to said monitor to synchronize horizontal scanning of said screen to the receipt of said distinct portions of said information signal,

means for generating digital words each defining a single discrete change of said variable delay time,

means operative during the continued transmission of said information and synchronizing signals for responding to each of said generated digital words by effecting the discrete change of said variable delay time defined by said each generated digital word to effect horizontal movement of the information displayed on said screen to prevent burn-in of said screen and

means responsive to said blanking signal for disabling the transmission of said information signal by said information signal transmitting means during said time intervals.

11. Display apparatus in accordance with claim 10 wherein said means for generating a synchronizing signal comprises

means for generating at least one delayed version of said blanking signal and

selection means for generating said synchronizing signal by selecting one signal from the plurality of signals comprising said blanking signal and said at least one delayed version of said blanking signal,

and wherein said responding means comprises means for changing the selection made by said selection means in response to said each generated digital word.

12. Display apparatus in accordance with claim 10 wherein said means for generating a synchronizing signal comprises

means for generating a plurality of delayed versions of said blanking signal and

selection means for generating said synchronizing signal by selecting one signal from said plurality of delayed versions of said blanking signal,

and wherein said responding means comprises means for changing the selection made by said selection means in response to said each generated digital word.

13. Display apparatus comprising

a monitor having a screen for displaying information thereon,

means for transmitting an information signal to said monitor representing information to be displayed on said screen,

means for generating a blanking signal in fixed temporal relation to said information signal to define time intervals between distinct units of said information signal, each said unit representing information to be displayed on a separate frame on said screen,

means for generating a synchronizing signal by delaying said blanking signal by a variable delay time, where said variable delay time may be zero,

means for transmitting said synchronizing signal to said monitor to synchronize vertical scanning of said screen to the receipt of said distinct units of said information signal,

means for generating digital words each defining a single discrete change of said variable delay time,

means operative during the continued transmission of said information and synchronizing signals for responding to each of said generated digital words by effecting the discrete change of said variable delay time defined by said each generated digital word to effect vertical movement of the information displayed on said screen to prevent burn-in of said screen and

means responsive to said blanking signal for disabling the transmission of said information signal by said information signal transmitting means during said time intervals.

14. Display apparatus in accordance with claim 13 wherein said means for generating a synchronizing signal comprises

means for generating a clock signal and

counter means responsive to said blanking signal for initiating counting of transitions of said clock signal and for generating said synchronizing signal upon reaching a predeterined count and

wherein said responding means comprises means for changing the predetermined count to be reached by said counter means in response to said each generated digital word.

15. Apparatus for operating a monitor that displays information on a screen comprising

controller means for transmitting coded characters, a horizontal retrace signal defining time intervals between lines of said coded characters, and a vertical retrace signal defining time intervals between frames of said lines,

conversion means responsive to said coded characters transmitted by said controller means for converting said coded characters to a video information signal representing said coded characters, said converting resulting in a substantially fixed time delay of said video information signal with respect to said coded characters transmitted by said controller means,

means for transmitting said video information signal to said monitor,

means for delaying said horizontal and vertical retrace signals by said substantially fixed time delay,

means responsive to said delayed horizontal and vertical retrace signals for disabling the transmission of said video information signal by said means for transmitting said video information signal,

delay line means for generating at least one delayed version of said delayed horizontal retrace signal,

selector means for generating a horizontal synchronizing signal by selecting one signal from the plurality of signals comprising said delayed horizontal retrace signal and said at least one delayed version of said delayed horizontal retrace signal,

means for transmitting said generated horizontal synchronizing signal to said monitor to synchronize horizontal scanning of said screen,

means for generating a clock signal,

counter means responsive to said delayed vertical retrace signal for initiating counting of transitions of said clock signal and for generating a vertical synchronizing signal upon reaching a predetermined count,

means for transmitting said generated vertical synchronizing signal to said monitor to synchronize vertical scanning of said screen,

memory means for storing coded characters to be displayed on said screen and program instructions and

processor means for executing said program instructions to effect the transfer of coded characters from said memory means to said controller means and for repetitively changing the selection made by said selector means and the predetermined count to be reached by said counter means to prevent burn-in of said screen by effecting incremental horizontal and vertical displacement of the information displayed on said screen.