Flexible sheet for resistive touch screen

• US 20060102452A1
• Filed: 11/12/2004
• Published: 05/18/2006
• Est. Priority Date: 11/12/2004
• Status: Active Grant

• Current Assignee: Eastman Kodak Company
• Original Assignee: Eastman Kodak Company
• Inventors: Majumdar, Debasis, Cok, Ronald S., Freedman, Gary S., Irvine, Glen C. Jr.
• Granted Patent: US 7,230,198 B2
• Time in Patent Office: Days
• US Class Current: 200/5.A
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A resistive touch screen, comprising: a) a substrate; b) a first conductive layer located on the substrate; c) a flexible cover sheet having integral compressible spacer dots; and d) a second conductive layer located on the flexible cover sheet between and over the integral spacer dots, and having localized areas of lower conductivity over the integral compressible spacer dots relative to the conductivity of the conductive layer located on the flexible cover sheet between the integral spacer dots.

Claims

1. A resistive touch screen, comprising:

a) a substrate;

b) a first conductive layer located on the substrate;

c) a flexible cover sheet having integral compressible spacer dots; and

d) a second conductive layer located on the flexible cover sheet between and over the integral spacer dots, and having localized areas of lower conductivity over the integral compressible spacer dots relative to the conductivity of the conductive layer located on the flexible cover sheet between the integral spacer dots.

2. The resistive touch screen of claim 1, wherein the substrate, first conductive layer, flexible cover sheet, and second conductive layer are transparent.

3. The resistive touch screen of claim 2, wherein the substrate is rigid.

4. The resistive touch, screen claimed in claim 1, wherein the substrate of the touch screen is the substrate or cover of a flat-panel display device.

5. The resistive touch screen claimed in claim 4, wherein the flat-panel display device is an OLED display device.

6. The resistive touch screen of claim 1, wherein said flexible cover comprises one of the group including:

polymer, polyolefin polymer, polyester, polycarbonate, and a blend of polyester and polycarbonate.

7. The resistive touch screen of claim 1, wherein said integral compressible spacer dots comprise cylinder-shaped dots, cube-shaped dots, pyramid-shaped dots, or sphere-shaped dots.

8. The resistive touch screen of claim 1, wherein said substrate comprises a rigid material.

9. The resistive touch screen of claim 1, wherein the second conductive layer comprises an electrically conductive polymer.

10. The resistive touch screen of claim 9, wherein the conductive layer comprises one of the group including polypyrrole styrene sulfonate, 3,4-dialkoxy substituted polypyrrole styrene sulfonate, and 3,4-dialkoxy substituted polythiophene styrene sulfonate, poly(3,4-ethylene dioxythiophene styrene sulfonate.

11. The resistive touch screen of claim 9, wherein the localized areas of lower conductivity in the second conductive layer comprise areas contacted with a chemical.

12. The resistive touch screen of claim 11, wherein the chemical is an oxidant.

13. The resistive touch screen of claim 12, wherein the oxidant is selected from the group consisting of ClO⁻

, BrO⁻

, MnO₄⁻

, Cr₂O₇⁻

, S₂O₈⁻

and H₂O₂.

14. A method of making a resistive touch screen, comprising the steps of:

a) providing a substrate;

b) forming a first conductive layer on the substrate;

c) providing a flexible cover sheet having integral compressible spacer dots on the cover sheet;

d) forming a second conductive layer on the flexible cover sheet between and over the integral compressible spacer dots;

e) reducing the conductivity of the second conductive layer locally over the integral compressible spacer dots; and

f) locating the flexible cover sheet over the substrate such that when a force is applied to the flexible cover sheet at the location of one of the compressible spacer dots, the compressible spacer dot is compressed to allow electrical contact between the first and second conductive layers.

15. The method claimed in claim 14, wherein the flexible cover sheet is provided as a web in a continuous roll, the integral spacer dots are molded in the continuous roll, and the sheet is cut from the roll.

16. The method claimed in claim 14, wherein the integral spacer dots are formed in the flexible cover sheet by injection roll molding.

17. The method claimed in claim 14, wherein the spacer dots are formed in the flexible cover sheet by applying heat and pressure to the flexible cover sheet by a mold including a reverse image of the spacer dots.

18. The method claimed in claim 14, wherein the reduction in conductivity in step (e) is achieved through local deposition of a chemical on the second conductive layer over the integral spacer dots.

19. The method claimed in claim 18, wherein the deposition of the chemical is achieved with an inkjet device.

20. The method claimed in claim 18, wherein the second conductive layer forms peaks in areas over the spacer dots and deposition of the chemical is achieved by contacting the peaks of the second conductive layer with a chemically coated surface.

21. The method claimed in claim 20, wherein the coated surface is a roller.

22. The method of claim 18, wherein the second conductive layer comprises an electrically conductive polymer.

23. The method claimed in claim 22, wherein the chemical is an oxidant.

24. The method claimed in claim 23, wherein the oxidant is selected from the group consisting of ClO⁻

, BrO⁻

, MnO₄⁻

, Cr₂O₇⁻

, S₂O₈⁻

and H₂O₂.