Transparent coordinate detection device

• US 5,392,035 A
• Filed: 09/03/1993
• Issued: 02/21/1995
• Est. Priority Date: 11/30/1992
• Status: Expired due to Term

• Current Assignee: SMK Corporation
• Original Assignee: SMK Corporation
• Inventors: Yoshikawa, Osamu
• Primary Examiner(s): Young, Brian K.
• Application Number:
  US08/116,397
• Time in Patent Office: 536 Days
• Field of Search: 341/5, 341/17, 367/129, 178/18
• US Class Current: 341/5
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A coordinate detection device has upper and lower resistive plates. Pressure on the upper resistive plate causes the two plates to come into electrical contact at a point of the pressure allowing an external device to compute the coordinates of the applied pressure. Each resistive plate has a layer of transparent resistor material over a transparent substrate. Two parallel electrodes of silver are spaced apart on each resistive plate to create a linear potential gradient therebetween. The electrodes are connected across a voltage potential via lead wires which are made from the same material as the transparent resistor.

Claims

1. A transparent tablet for a transparent coordinate detection device comprising:

a plate having a transparent resistive film covering a tablet area thereof;

means for connecting said resistive film to a voltage potential;

said means for connecting being contiguous with said resistive film and integrally formed from said resistive film extending outside said tablet area; and

means for establishing a voltage gradient in said resistive film, between said means for connecting, said voltage gradient having a planar configuration with substantially linear equipotential lines on said transparent resistance plate.

2. A transparent tablet for a transparent coordinate detection device according to claim 1 wherein said means for connecting and said resistive film covering said tablet area are integrally formed from the same material, said material including one of ITO and silver oxide.

3. A transparent tablet for a transparent coordinate detection device according to claim 1, wherein said means for establishing further comprises:

first and second conductive electrodes; and

.

said first and second conductive electrodes being parallel and spaced a predetermined distance apart to define an Operational area of said tablet.

4. A transparent tablet for a transparent coordinate detection device according to claim 3, wherein said first and second conductive electrodes are substantially metallic and have a lower resistance than said transparent resistance plate.

5. A transparent tablet for a transparent coordinate detection device comprising:

a plate

a plate area having of a transparent resistance material thereon;

first and second electrodes contacting said transparent resistance material;

said first and second electrodes being aligned to produce a linear planar potential gradient therebetween;

first and second lead wires of transparent resistance material;

said first and second lead wires being connected to said first and second electrodes, respectively; and

means for permitting connection of said first and second lead wires across a voltage potential.

6. A transparent tablet for a transparent coordinate detection device according to claim 5, wherein said first and second lead wires are formed of the same transparent resistance material covering said plate area.

7. A transparent tablet for a transparent coordinate detection device according to claim 5, wherein said first and second lead wires and said transparent resistance material on said plate area are integrally formed.

8. A transparent tablet for a transparent coordinate detection device according to claim 5, wherein said desired linear equipotential gradient includes an equipotential distribution parallel to said first and second electrodes.

9. A transparent tablet for a transparent coordinate detection device comprising:

a transparent resistor plate;

first and second parallel metal electrodes on said plate being spaced apart a predetermined distance;

said transparent resistor plate including first and second lead portions adjacent to said first and second parallel metal electrodes, respectively;

said transparent resistor plate and said first and second lead portions being integrally formed from the same material; and

means for permitting connection of said first and second lead portions across a voltage potential.

10. A coordinate detection device, comprising;

upper and lower plates;

means for separating said upper and lower plates until a pressure is applied to one of said upper and lower plates;

said upper plate including a first pair of parallel metal electrodes;

said lower plate including a second pair of parallel metal electrodes;

said first pair of parallel metal electrodes being orthogonal to said second pair of electrodes;

means for selectively connecting said first and second pairs of parallel metal electrodes across a voltage potential;

said upper and lower plates including a transparent resistor between said first second pairs of parallel metal electrodes, respectively;

at least a portion of said means for selectively connecting being made from, and integrally formed with, a same material as said transparent resistor.