Coordinate position information output device

• US 3,944,740 A
• Filed: 07/22/1974
• Issued: 03/16/1976
• Est. Priority Date: 07/31/1973
• Status: Expired due to Term

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Murase, Kenji, Andoh, Shizuo
• Primary Examiner(s): Robinson, Thomas A.
• Application Number:
  US05/490,337
• Time in Patent Office: 603 Days
• Field of Search: 307/320, 178/18, 178/19, 340/324 R, 340/324 M
• US Class Current: 178/18.05
• CPC Class Codes: G03B 15/00 Special procedures for taking photographs; Apparatus therefor
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: G09B 29/102 using electrical means
• CPC Class Codes: G09B 29/106 using electronic means

Abstract

A coordinate position information output device is disclosed in which the impedance at a position addressed by a contact pen, a light pen, a magnetic pen or the like is varied; a forward current is caused to flow by the impedance change in a charge storage diode; and a backward current flowing in the charge storage diode for a moment immediately thereafter is utilized as coordinate position information.

Claims

1. A coordinate position information output apparatus comprising:

a. a coordinate position indicating plate having a plurality of row electrodes and a plurality of column electrodes intersectingly disposed thereon defining intersection points, and an impedance element located at each intersection point of said electrodes;

b. an external address means for addressing selected intersection points and thereby reducing the impedance and establishing a current path between corresponding electrodes;

c. a plurality of unidirectional conducting elements each having a relatively long charge storage time and respectively connected to a corresponding one of row and column electrodes to provide a unidirectional current conducting path to each of said intersecting points;

d. a first circuit means for applying a forward voltage to said unidirectional conducting elements causing charge to be stored and a forward current to flow in said unidirectional conducting elements corresponding to addressed intersecting points of said plate;

e. second circuit means for applying a reverse voltage to said unidirectional conducting elements substantially immediately after the termination of said forward voltage, causing reverse current to flow in said undirectional conducting elements connected to said electrodes corresponding to addressed intersecting points; and

f. a matrix display device including a plurality of input conductors each corresponding to a respective one of said row and column electrodes, each of said input conductors being connected to respective ones of said unidirectional conducting elements;

whereby coordinate display information is supplied to said matrix display device by said input conductors as said reverse current flows in said unidirectional conducting elements in proportion to the charge stored therein.

2. A coordinate position information apparatus as in claim 1 wherein said second circuit means applies a reverse voltage of +Vw/2 to said unidirectional conducting elements corresponding to said plurality of row electrodes, and a reverse voltage of -Vw/2 to said unidirectional conducting elements corresponding to said plurality of column electrodes, wherein Vw is the write voltage for the matrix display device.

3. A coordinate information output apparatus as in claim 1 wherein said matrix display device includes a plurality of display electrodes respectively connected to said plurality of input conductors, said display electrodes disposed within said matrix display device to provide current paths for said reverse current from respective ones of said unidirectional conducting elements.

4. A coordinate position information output apparatus as in claim 1 further comprising timing signal means controlling said first and second circuits for alternately and periodically applying said forward voltages and said reverse voltages respectively to said unidirectional conducting elements.

5. A coordinate position information output apparatus as in claim 3 wherein the angles of intersection between the plurality of row electrodes and the plurality of column electrodes disposed on said coordinate position indicating plate are different than the angles of intersection between corresponding electrodes and said matrix display device.

6. A coordinate position information output apparatus as in claim 3 wherein said plurality of row electrodes and said plurality of column electrodes have a non-linear relationship to said corresponding plurality of electrodes in said matrix display device.

7. A coordinate position information output apparatus according to claim 1 wherein said coordinate position indicating plate is curved.

8. A coordinate position information output apparatus comprising:

a coordinate position indicating plate with a first surface, a plurality of row electrodes and a plurality of column electrodes disposed on said first surface forming electrode intersecting points and defining address points, impedance element means establishing electrical resistance between said plurality of row electrodes and said plurality of column electrodes at said intersecting points;

an external addressing means for lowering the resistance between said row electrodes and said column electrodes corresponding to selected address points;

a first circuit means including a plurality of charge storage diodes, each of which is connected to a corresponding one of said row and column electrodes, said first circuit means applying a forward voltage to said charge storage diodes, said charge storage diodes being connected to said electrodes so as to maintain a forward current flow through said corresponding charge storage diodes when said corresponding address point is addressed by said external address means and said forward voltage is applied;

second circuit means connected to said charge storage diodes and applying a reverse voltage thereto at the termination of said forward voltage causing said charge storage diodes which were maintaining a forward current flow to momentarily maintain a reverse current flow;

a matrix display panel having a first set of electrodes which correspond to said plurality of row electrodes, a second set of electrodes which correspond to said plurality of column electrodes, wherein said first set of electrodes form intersections with said second set of electrodes and are separated by a display medium, said intersections defining display points on said matrix display panel, each electrode of said first and second sets of electrodes being connected to a respective one of said charge storage diodes whereby said reverse current flows in said corresponding electrodes of said first and second sets of electrodes, thereby activating said display medium in said matrix display panel corresponding to said address points.

9. A coordinate position information output apparatus as in claim 8, wherein said matrix display panel is a plasma display panel and said display medium is a discharge gas.

10. A coordinate position information output apparatus as in claim 8, wherein said external address means is a conducting element which, when applied to a selected one of said address points, causes a corresponding one of said row electrodes and a corresponding one of said column electrodes to be short circuited.

11. A coordinate position information output apparatus according to claim 8, wherein said impedance element is pressure-sensitive and is characterized by a decrease in resistance with an increase in pressure, and said external addressing means is a device for applying pressure to selected ones of said address points, thereby causing forward current to flow between corresponding ones of said row electrodes and said column electrodes.

12. A coordinate position information output apparatus according to claim 8, wherein said impedance element is a photo conductor, and said external addressing means is a light source for addressing selected ones of said address points, thereby causing forward current to flow between corresponding ones of said plurality of row electrodes and said plurality of column electrodes.

13. A coordinate position information output apparatus according to claim 8, further comprising leakage preventing means connected between said charge storage diodes and said plurality of row electrodes and said plurality of column electrodes allowing forward current to flow therethrough when a corresponding address point is addressed and preventing said reverse current from flowing therethrough.