Electrographic apparatus

• US 4,649,232 A
• Filed: 06/07/1985
• Issued: 03/10/1987
• Est. Priority Date: 06/07/1985
• Status: Expired due to Term

• Current Assignee: Frances B. Cuniberti, Scriptel Corporation, Walter T. Krumm
• Original Assignee: Scriptel Corporation
• Inventors: Nakamura, Shiochiro, Kable, Robert G.
• Primary Examiner(s): SCHREYER, STAFFORD
• Application Number:
  US06/742,734
• Time in Patent Office: 641 Days
• Field of Search: 178/18, 178/19, 178/20
• US Class Current: 178/18.05
• CPC Class Codes: G01B 7/004 for measuring coordinates of points
• CPC Class Codes: G01D 5/16 by varying resistance
• CPC Class Codes: G01D 5/165 by relative movement of a point of contact or actuation and a resistive track
• CPC Class Codes: G06F 2203/04113 Peripheral electrode pattern in resistive digitisers, i.e. electrodes at the periphery of the resistive sheet are shaped in patterns enhancing linearity of induced field
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

An electrographic apparatus and system utilizing a resistive layer having an active area which operates in conjunction with a stylus or tracer or other suitable position locator. An a.c. source or alternatively a signal treatment means is connected to the resistive layer through rows of electrodes. Improved accuracy is achieved through the use of electrodes at the ends of the electrode rows and through the use of an enhanced conductivity region which also allows the boundary of the active area to be placed in close proximity to the electrodes.

Claims

1. An electrographic system comprising:

an electrically insulative substrate;

a resistive layer supported upon said insulative substrate and having an active area extending in an x- coordinate direction between first and second spaced apart edges and extending in a y- coordinate direction between third and fourth spaced-apart edges;

a first row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said first edge;

a second row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said second edge;

a third row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said third edge;

a fourth row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said fourth edge;

first corner electrode means coupled with said resistive layer at the juncture of said first and third rows;

second corner electrode means coupled with said resistive layer at the juncture of said first and fourth rows;

third corner electrode means coupled with said resistive layer at the juncture of said second and third rows;

fourth corner electrode means coupled with said resistive layer at the juncture of said second and fourth rows;

a position locator adjacent said active area;

a time varying excitation source of select frequency;

a ground reference;

switching means for applying said ground reference to said first row of electrodes and to said first and second corner electrodes and simultaneously applying said source to said second row of electrodes and to said third and fourth corner electrodes and electrically isolating said third and fourth rows of electrodes during a first operational mode, for reversing said applications of said ground reference and said source to said first and second rows of electrodes and to said first, second, third, and fourth corner electrodes and maintaining said electrical isolation of said third and fourth rows of electrodes during a second operational mode, for applying said ground reference to said third row of electrodes and to said first and third corner electrodes and simultaneously applying said source to said fourth row of electrodes and to said second and fourth corner electrodes and electrically isolating said first and second rows of electrodes during a third operational mode, and for reversing said applications of said ground reference and said source of said third and fourth rows of electrodes and to said first, second, third and fourth corner electrodes and maintaining said electrical isolation of said first and second rows of electrodes during a fourth operational mode; and

control means for collecting a signal from said position locator.

2. An electrographic system comprising:

an electrically insulative substrate;

a resistive layer supported upon said insulative substrate and having an active area extending in an x- coordinate direction between first and second spaced apart edges and extending in a y- coordinate direction between third and fourth spaced-apart edges;

a first row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said first edge;

a second row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said second edge;

a third row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said third edge;

a fourth row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said fourth edge;

first corner electrode means coupled with said resistive layer at the juncture of said first and third rows;

second corner electrode means coupled with said resistive layer at the juncture of said first and fourth rows;

third corner electrode means coupled with said resistive layer at the juncture of said second and third rows;

fourth corner electrode means coupled with said resistive layer at the juncture of said second and fourth rows;

a time varying excitation source of select frequency;

a position locator adjacent said active area for inputting said source at a select position in said active area;

signal treatment means;

a ground reference;

switching means for applying said ground reference to said first row of electrodes and to said first and second corner electrodes and simultaneously applying said signal treatment means to said second row of electrodes and to said third and fourth corner electrodes and electrically isolating said third and fourth rows of electrodes during a first operational mode, for reversing said applications of said ground reference and said signal treatment means to said first and second rows of electrodes and to said first, second, third and fourth corner electrodes and maintaining said electrical isolation of said third and fourth rows of electrodes during a second operational mode, for applying said ground reference to said third row of electrodes and to said first and third corner electrodes and simultaneously applying said signal treatment means to said fourth row of electrodes and to said second and fourth corner electrodes and electrically isolating said first and second rows of electrodes during a third operational mode, and for reversing said applications of said ground reference and said signal treatment means to said third and fourth rows of electrodes and to said first, second, third and fourth corner electrodes and maintaining said electrical isolation of said first and second rows of electrodes during a fourth operational mode.

3. An electrographic system comprising:

an electrically insulative substrate;

a resistive layer supported upon said insulative substrate and having an active area extending in an x- coordinate direction between first and second spaced apart edges and extending in a y- coordinate direction between third and fourth spaced-apart edges said resistive layer being provided as a coating of indium-tin-oxide having a thickness selected for exhibiting a resistivity of about 600 ohms per square;

a first row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said first edge;

a second row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said second edge;

a third row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said third edge;

a fourth row of discrete, spaced-apart electroes electrically coupled with said resistive layer intermediate said active area and said fourth edge;

one electrode in said first row of electrodes being positioned at the end of said first row adjacent said third row and another electrode in said first row being positioned at the opposite end of said first row adjacent said fourth row;

one electrode in said second row of electrodes being positioned at the end of said second row adjacent said third row and another electrode in said second row being positioned at the end of said second row adjacent said fourth row;

one electrode in said third row of electrodes being positioned at the end of said third row adjacent said first row and another electrode in said third row being positioned at the opposite end of said third row adjacent said second row;

one electrode in said fourth row of electrodes being positioned at the end of said fourth row adjacent said first row and another electrode in said fourth row being positioned at the opposite end of said fourth row adjacent said second row;

an enhanced conductivity region intermediate said active area and said electrodes, said region being formed of a layer of indium-tin-oxide supported by said substrate and having a thickness selected for exhibiting a resistivity of about 60 ohms per square;

a position locator adjacent said active area;

a time varying excitation source of select frequency;

a ground reference;

switching means for applying said ground reference to said first row of electrodes and simultaneously applying said source to said second row of electrodes and electrically isolating said third and fourth rows of electrodes during a first operational mode, for reversing said applications of said ground reference and said source to said first and second rows of electrodes and maintaining said electrical isolation of said third and fourth rows of electrodes during a second operational mode, for applying said ground reference to said third row of electrodes and simultaneously applying said source to said fourth row of electrodes and electrically isolating said first and second rows of electrodes during a third operational mode, and for reversing said applications of said ground reference and said source to said third and fourth rows of electrodes and maintaining said electrical isolation of said first and second rows of electrodes during a fourth opertional mode; and

control means for collection a signal from said position locator.

4. An electrographic system comprising:

an electrically insulative substrate;

a resistive layer supported upon said insulative substrate and having an active area extending in an x- coordinate direction between first and second spaced apart edges and extending in a y- coordinate direction between third and fourth spaced-apart edges, said resistive layer being provided as a coating of indium-tin-oxide having a thickness selected for exhibiting a resistivity of about 600 ohms per square;

a first row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said first edge;

a second row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said second edge;

a third row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said third edge;

a fourth row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said fourth edge;

one electrode in said first row of electrodes being positioned at the end of said first row adjacent said third row and another electrode in said first row being positioned at the opposite end of said first row adjacent said fourth row;

one electrode in said second row of electrodes being positioned at the end of said second row adjacent said third row and another electrode in said second row being positioned at the end of said second row adjacent said fourth row;

one electrode in said third row of electrodes being positioned at the end of said third row adjacent said first row and another electrode in said third row being positioned at the opposite end of said third row adjacent said second row; and

one electrode in said fourth row of electrodes being positioned at the end of said fourth row adjacent said first row and another electrode in said fourth row being positioned at the opposite end of said fourth row adjacent said second row;

a time varying excitation source of select frequency;

an enhanced conductivity region intermediate said active area and said electrodes, said region being formed of a layer of indium-tin-oxide supported by said substrate and having a thickness selected for exhibiting a resistivity of about 60 ohms per square;

a position locator adjacent said active area for inputting said source at a select location in said active area;

signal treatment means;

a ground reference; and

switching means for applying said ground reference to said first row of electrodes and simultaneously applying said signal treatment means to said second row of electrodes and electrically isolating said third and fourth rows of electrodes during a first operational mode, for reversing said applications of said ground reference and said signal treatment means to said first and second rows of electrodes and maintaining said electrical isolation of said third and fourth rows of electrodes during a second operational mode, for applying said ground reference to said third row of electrodes and simultaneously applying said signal treatment means to said fourth row of electrodes and electrically isolating said first and second rows of electrodes during a third operational mode, and for reversing said applications of said ground reference and said signal treatment means to said third and fourth rows of electrodes and maintaining said electrical isolation of said first and second rows of electrode during a fourth operational mode.

5. An improved graphics tablet for an electrographic system comprising:

an electrically insulative substrate;

a resistive layer supported upon said insulative substrate and having an active area extending in an x- coordinate direction between first and second spaced apart edges and extending in a y- coordinate direction between third and fourth spaced-apart edges;

a first row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said first edge;

a second row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said second edge;

a third row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said third edge;

a fourth row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said fourth edge;

first corner electrode means coupled with said resistive layer at the juncture of said first and third rows;

second corner electrode means coupled with said resistive layer at the juncture of said first and fourth rows;

third corner electrode means coupled with said resistive layer at the juncture of said second and third rows;

fourth corner electrode means coupled with said resistive layer at the juncture of said second and fourth rows; and

an enhanced conductivity region intermediate said active area and said electrodes.

6. The improved graphics tablet of claim 5 wherein the bulk resistivity of said enhanced conductivity region is different from the bulk resistivity of said active region.

7. An electrographic system comprising:

an electrically insulative substrate;

a resistive layer supported upon said insulative substrate and having an active area extending to an x- coordinate direction between first and second spaced apart edges and extending in a y- coordinate direction between third and fourth spaced-apart edges;

a first row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said first edge;

a second row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said second edge;

a third row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said third edge;

a fourth row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said fourth edge;

an enhanced conductivity region intermediate said active area and said electrodes;

first corner electrode means coupled with said resistive layer at the juncture of said first and third rows;

second corner electrode means coupled with said resistive layer at the juncture of said first and fourth rows;

third corner electrode means coupled with said resistive layer at the juncture of said second and third rows;

fourth corner electrode means coupled with said resistive layer at the juncture of said second and fourth rows;

a position locator adjacent said active area;

a time varying excitation source of select frequency;

a ground reference;

switching means for applying said ground reference to said first row of electrodes and to said first and second corner electrodes and simultaneously appying said source to said second row of electrodes and to said third and fourth corner electrodes and electrically isolating said third and fourth rows of electrodes during a first operational mode, for reversing said applications of said ground reference and said source to said first and second rows of electrodes and to said first, second, third and fourth corner electrodes and maintaining said electrical isolation of said third and fourth rows of electrodes during a second operational mode, for applying said ground reference to said third row of electrodes and to said first and third corner electrodes and simultaneously applying said source to said fourth row of electrodes and to said second and fourth corner electrodes and electrically isolating said first and second rows of electrodes during a third operation mode, and for reversing said applications of said ground reference and said source to said third and fourth rows of electrodes and to said first, second, third, and fourth corner electrodes and maintaining said electrical isolation of said first and second rows of electrodes during a fourth operational mode; and

control means for collecting a signal from said position locator.

8. An electrographic system comprising:

an electrically insulative substrate;

a resistive layer supported upon said insulative substrate and having an active area extending in an x- coordinate direction between first and second spaced apart edges and extending in a y- coordinate direction between third and fourth spaced-apart edges;

a first row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said first edge;

a second row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said second edge;

a third row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said third edge;

a fourth row of discrete, spaced-apart electrodes electrically coupled with said resistive layer intermediate said active area and said fourth edge;

an enhanced conductivity region intermediate said active area and said electrodes;

first corner electrodes means coupled with said resistive layer at the juncture of said first and third rows;

second corner electrode means coupled with said resistive layer at the juncture of said first and fourth rows;

third corner electrode means coupled with said resistive layer at the juncture of said second and third rows;

fourth corner electrode means coupled with said resistive layer at the juncture of said second and fourth rows;

a time varying excitation source of select frequency;

a position locator adjacent said active area for inputting said source at a select position in said active area;

signal treatment means;

a ground reference; and

switching means for applying said ground reference to said first row of electrodes and to said first and second corner electrodes and simultaneously appying said signal treatment means to said second row of electrodes and to said third and fourth corner electrodes and electrically isolating said third and fourth rows of electrodes during a first operational mode, for reversing said applications of said ground reference and said signal treatment means to said first and second rows of electrodes and to said first, second, third and fourth corner electrodes and maintaining said electrical isolation of said third and fourth rows of electrodes during a second operation mode, for applying said ground reference to said third row of electrodes and to said first and third corner electrode and simultaneously applying said signal treatment means to said fourth row of electrodes and to said second and fourth corner electrodes and electrically isolating said first and second rows of electrodes during a third operational mode, and for reversing said applications of said ground reference and said signal treatment means to said third and fourth rows of electrodes and to said first, second, third, and fourth corner electrodes and maintaining said electrical isolation of said first and second rows of electrodes during a fourth operational mode.