Method of and system for light pen read-out and tablet writing of multicelled gaseous discharge display/memory device

• US 3,875,472 A
• Filed: 06/29/1973
• Issued: 04/01/1975
• Est. Priority Date: 06/29/1973
• Status: Expired due to Term

• Current Assignee: Techneglas LLC (Nippon Electric Glass Company Limited)
• Original Assignee: Jerry D. Schermerhorn
• Inventors: Schermerhorn, Jerry D.
• Primary Examiner(s): Rolinec, Rudolph V.
• Assistant Examiner(s): LaRoche, E. R.
• Application Number:
  US05/375,083
• Time in Patent Office: 641 Days
• Field of Search: 315/169R,169TV 340/173PL,324R,324M 178/18,19
• US Class Current: 345/182
• CPC Class Codes: G06F 3/0386 for light pen

Abstract

Identification of coordinates of a region of a display device and the discharge state of that region is accomplished by means of a randomly positionable light detector and appropriate controls for selectively and non-destructively altering the discharge state of discharge sites in the device. A device offering spatial discharge transfer between discharge sites of individual cells such that if any site of a cell is in the '"'"''"'"''"'"''"'"'on state'"'"''"'"''"'"''"'"' of discharge the remaining sites of that cell will be transferred to an '"'"''"'"''"'"''"'"'on state'"'"''"'"''"'"''"'"' has its cell coordinates scanned by transferring a portion of the '"'"''"'"''"'"''"'"'on'"'"''"'"''"'"''"'"' sites of a cell to an off state to emit a localized light pulse while the cells of the device are otherwise in a non-light-emitting state. The light detector is gated only during that non-light-emitting state for successive cycles of operation in which the cell matrix is scanned with partial '"'"''"'"''"'"''"'"'turn off'"'"''"'"''"'"''"'"' signals and marks the scan area at the moment the detector responds to the light emitted by the turn off discharge. Since only a portion of a cell is erased, the remainder thereof retains its original state and that memory retaining remainder restores the erased portion to an on state of discharge, the readout by this light detector is non-destructive of the cell memory. Off state cells can be detected by inverting the discharge state of the panel and scanning cells by partial turn off signals. Increased speed of scan is achieved by actuating blocks of the cell matrix and localizing the region to be scanned in detail.

Claims

1. A method of ascertaining the location of a gaseous discharge display/memory cell in a matrix of such cells, each cell comprising proximate portions of conductors in each of two conductor arrays, an ionizable gas volume in the vicinity of the proximate conductor portions, and a dielectric layer separating at least one conductor portion from said gas volume, each cell having at least two electrically independent conductor portions in one array in sufficient proximity to each other and to the cell'"'"''"'"'s conductor portion in the second array to form plural discharge sub sites between conductors of the respective arrays such that an on state of discharge in any sub site of the cell causes an on state of discharge in the remaining sub sites of the cell, said method comprising the steps of:

applying a sustaining potential waveform across the two conductor arrays;

sequentially creating light emiting discharges in selected sub sites of the matrix during dormant time periods of cell response to the sustaining potentials while maintaining the internal information content of the cells;

detecting light emitted over a restricted area oF the matrix during the dormant time periods of cell response to the sustaining potentials; and

restricting the light emitting discharge in selected cells of the matrix during dormant time periods of cell response to less than all sub sites of each selected cell.

2. The method according to claim 1 including the step of scanning the cell matrix with the sequentially created light emitting discharges.

3. The method according to claim 1 wherein the conductors of one array lie in a first surface and extend generally along one axis and the conductors of the other array lie in a surface equally spaced from the first surface and extend generally along another axis to define at the proximate conductor portions of each cell cross points with the conductors of the one array as viewed along mutual perpendiculars to the arrays, wherein the step of sequentially creating light emitting discharges is practiced first transverse of one array and then transverse of the other array whereby the light detection, and correlation of light emission with the location of the selected cell is transverse of each array.

4. The method according to claim 1 wherein the matrix of cells extends along two axes transverse to each other and including the step of scanning the cell matrix along one of the axes with the sequentially created light emitting discharges whereby detection of a discharge indicates the coordinate of the matrix along the one axis of the restricted area of detection.

5. The method according to claim 4 including the step of scanning the cell matrix along the other of the two axes with the sequentially created light emitting discharges whereby detection of a discharges whereby detection of a discharge inicates the coordinate of the matrix along the other of the two axes of the restricted area of detection.

6. The method according to claim 1 wherein the step of creating light emitting discharges is applied to cells in the on state of discharge.

7. The method according to claim 2 including the steps of:

shifting the level of the sustaining voltage waveform applied across the two conductor arrays whereby the state of discharge of all cells in the matrix is inverted and the wall voltage of cells in the on state of discharge is at a level relative to the shifted sustaining voltage level of the wall voltage of cells in an off state of discharge and the wall voltage of cells in the off state of discharge is at a level relative to the shifted sustaining voltage level of the wall voltage of cells in an on state of discharge;

correlating the level of the sustaining voltage waveform with the detection of emitted light to indicate the discharge state, during application of the unshifted sustaining voltage, of the cell within the matrix restricted area subject to detection.

8. The method according to claim 7 wherein a detection of emitted light during application of an unshifted sustainer waveform indicates the cell is in an on state of discharge.

9. The method according to claim 7 wherein a detection of emitted light during application of a shifted sustainer waveform indicates the cell is in an off state of discharge.

10. The method according to claim 1 wherein each cell is comprised of a plurality of discharge sub sites having independent manipulating signal sources including the step of restricting the light emitting discharge in selected cells during dormant time periods of cell response to less than all discharge sub sites of each selected cell.

11. The method according to claim 10 wherein the matrix of cells extends as lines of cells along a first axis and the discharge sub sites of cells extend as lines of sub sites proximate to each other along the cell lines including the steps of electrically segregating lines of discharge sub sites common to cell lines;

grouping a line of discharge sub sites of each cell in respective first and second sets;

electrically paralleling a plurality of discharge sub site lines of the first set and the second set into a plurality of sections of sub site lines, each cell lin including lines of discharge sub sites from a unique combination of the first set sections and the second set sections;

scanning the first set sections with the sequentially created light emitting discharges, whereby detection of a discharge indicates the first set section location of the restricted area of detection;

scanning the second set sections with the sequentially created light emitting discharges, whereby detection of a discharge indicates the second set section location of the restricted area of detection and, in combination with the first set section indicated, the unique combination of first and second set sections of a coordinate along the first axis.

12. The method according to claim 11 wherein the first set sections are divided into divisions comprising a plurality of set sections and the scanning of the first set sections is performed as a coarse scan of the divisions, whereby detection of a discharge indicates the division including the first set section location of the restricted area of detection, and as a fine scan of the first set sections in the indicated division, whereby detection of a discharge indicates the first set section location of the restricted area of detection.

13. The method according to claim 12 wherein the second set sections are divided into second divisions comprising a plurality of set sections and the scanning of the second set sections is performed as a coarse scan of the second divisions, whereby detection of a discharge indicates the division including the second set section location of the restricted area of detection, and as a fine scan of the second set sections of the indicated division, whereby detection of a discharge indicates the second set section location of the restricted area of detection.

14. The method according to claim 10 wherein the light emitting discharge in selected cells during dormant time periods of cell response is produced by the step of applying an erase signal to discharge sub sites of selected cells which are in the on state of discharge.

15. The method according to claim 14 including the steps of inverting the state of discharge of all cells in the matrix by shifting the level of the sustaining voltage waveform;

sequentially creating light emitting discharges in selected cells of the matrix during dormant time periods of cell response to the shifted sustaining voltage; and

correlating the level of the sustaining voltage waveform with the detection of emitted light to indicate the discharge state, during the application of the unshifted sustaining voltage, of the cell within the matrix restricted area subject to detection.

16. The method according to claim 14 including the step of returning the erased sub sites to the on state of discharge by spatial discharge transfer during the major transition of the sustainer voltage waveform next following the erase signal.

17. A system for identifying the location of a discharge cell in a gaseous discharge display/memory device having a matrix of discharge cells, each cell comprising proximate portions of conductors in each of two conductor arrays, an ionizable gas volume in the vicinity of the proximate conductor portions, and a dielectric layer separating at least one conductor portion from said gas volume, each cell having at least two electrically independent conductor portions in one array in sufficient proximity to each other and to the cell'"'"''"'"'s conductor portion in the second array to form plural discharge sub sities between conductors of the respective arrays such that an on state of discharge in any sub site of the cell causes an on state of discharge in the remaining sub sites of the cell, means for applying a periodic pulsating sustainer voltage across said cells to cause periodic inoization discharges in cells which are in the on state of discharge, each periodic discharge being spaced apart by a normally non-light-emitting interval;

means for selectively applying erase signals on selected sub sites of said cells during a selected normally non-light-emitting interval;

a light pickup element having a limited area field of response;

a light detector in communication with said light pickup element and responsive to light picked up from selected sub sites by said element only during normally non-light-emitting intervals; and

marking means responsive to the detection of light by said light detector for marking the location of a cell which issued detected light from a sub site.

18. A system according to claim 17 wherein said matrix of cells comprises lines of cells extending along two axes and including scan control means to control the cell location of application of successive non-destructive erase signals along a first axis;

and scan control means to control the cell location of application of successive non-destructive erase signals to different locations along a second axis.

19. A system according to claim 17 including means to shift said sustainer voltage level to invert the discharge state of the cells of the matrix;

and means responsive to the sustainer voltage level imposed coincident with light detection by said light detector to indicate the state of discharge of the cell within the field of said pickup element when subjected to the unshifted sustainer level.

20. A system according to claim 17 wherein each cell is comprised of a plurality of discharge sub sites so spaced as to interact by spatial discharge transfer and including means to maintain the discharge state of one sub site of each cell to which said non-destructive erase signals are applied, whereby said one sub site of a cell in the on state of discharge returns its cell to its on state of discharge following application of said non-destructive erase signal.

21. A system according to claim 20 wherein said matrix cells comprise lines of cells extending along an axis and said lines of cells comprise at least two lines of discharge sub sites for each line of cells, parallel connections grouping sub sites lines of different cells into first and second sets of sub site lines and into respective pluralities of sections of sub site lines, each cell line including lines of sub sites from a unique combination of said first set sections and said second set sections;

scan control means to control the sub site line locations of application of successive non-destructive erase signals to different sections of said first set sections; and

scan control means to control the sub site line locations of application of successive non-destructive erase signals to different sections of said second set sections.

22. A system according to claim 17 including scan control means to control the cell location of application of successive non-destructive erase signals to different cell locations.

23. A system according to claim 22 wherein said scan control includes coarse scan means to apply successive non-destructive erase signals to different divisions of the cell matrix, each division including a plurality of cell locations;

wherein said marking means marks the division in which is located the cell which issued the detected light; and

fine scan means to apply successive non-destructive erase signals to cell locations within the division marked by said marking means.