Touch panel input device

• US 6,522,322 B1
• Filed: 10/14/1999
• Issued: 02/18/2003
• Est. Priority Date: 03/30/1999
• Status: Expired due to Term

• Current Assignee: SMK Corporation
• Original Assignee: SMK Corporation
• Inventors: Tanaka, Hiroshi, Sakurada, Hidemasa, Maeda, Toshifumi
• Primary Examiner(s): CHOW, DOON Y
• Application Number:
  US09/417,567
• Time in Patent Office: 1,223 Days
• Field of Search: 345/173, 345/174, 345/156, 345/157, 345/179, 428/337, 178/18-1-, 178/19-1-, 341/22, 341/34, 341/32, 341/33
• US Class Current: 345/173
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A transparent insulative liquid is sealed between two transparent plates that are coated with transparent conductor layers on their mutually facing surfaces of a touch panel input device. The facing surface of at least one of the transparent plates is roughened. Because the conductor layer is applied directly over the roughened surface of the transparent plate, the conductor layer is also roughened. When the entire device is tilted, the insulative liquid settles downward allowing the upper conductor layers to come into contact with each other, but because the surface is roughened only the protrusions of the conductor layer make contact. The overall contact resistance does not decrease sufficiently to be interpreted as a pressing operation. When a pressing operation is made, the insulative liquid flows into the depressions created by the roughened surface of the conductor layer. Because the liquid is not interposed between conductor layers, sure contact is made, and the pressed position requires only a light pressing force.

Claims

1. A touch panel input device, comprising;

an outer transparent plate;

said outer transparent plate having a first surface and a second surface;

an inner transparent plate;

said inner transparent plate having a third surface and a fourth surface;

said second surface and said third surface facing each other across a gap;

at least one of said second and third surfaces having a roughened surface;

a first transparent conductive layer coating said second surface;

a second transparent conductive layer coating said third surface;

a transparent insulative liquid substantially filling said gap;

a flexible seal interposed between perimeters of said second and third surfaces to seal said gap;

a position detection means electrically connected to said first conductive layer of said outer transparent plate and said second conductive layer of said inner transparent plate to interpret a contact position when said first transparent conductor layer is pressed sufficiently against said second transparent conductive layer; and

said transparent insulative liquid is silicon oil having a viscosity of between 5-20 cp.

2. A touch panel input device comprising:

an outer transparent plate;

said outer transparent plate having a first surface and a second surface;

an inner transparent plate;

said inner transparent plate having a third surface and a fourth surface;

said second surface and said third surface facing each other across a gap;

at least one of said second and third surfaces having a roughened surface;

a first transparent conductive layer coating said second surface;

a second transparent conductive layer coating said third surface;

a transparent insulative liquid substantially filling said gap;

a flexible seal interposed between perimeters of said second and third surfaces to seal said gap;

a position detection means electrically connected to said first conductive layer of said outer transparent plate and said second conductive layer of said inner transparent plate to interpret a contact position when said first transparent conductor layer is pressed sufficiently against said second transparent conductive layer; and

said roughened surface has a roughness in the range of from about 0.2 to about 0.4 microns.

3. A process for making a touch panel device comprising:

roughening a first surface of a first transparent plate;

coating said first surface with a first transparent conductive layer;

coating a second surface of a second transparent plate with a second transparent conductive layer;

assembling said first and second transparent plates with said first and second surfaces facing each other separated by a gap;

filling said gap with an insulative liquid;

sealing perimeters of said of first and second transparent plates to each other to seal said gap; and

inserting a position detection means electrically connected to said first conductive layer of said outer transparent plate and said second conductive layer of said inner transparent plate to interpret a contact position when said first transparent conductor layer is pressed sufficiently against said second transparent conductive layer, wherein the step of roughening includes roughening to a roughness of from about 0.2 to about 0.4 microns.

4. A process according to claim 3 wherein the step of roughening includes photoetching to produce said roughness.

5. A process for making a touch panel device comprising:

roughening a first surface of a first transparent plate;

coating said first surface with a first transparent conductive layer;

coating a second surface of a second transparent plate with a second transparent conductive layer;

assembling said first and second transparent plates with said first and second surfaces facing each other separated by a gap;

filling said gap with an insulative liquid;

sealing perimeters of said of first and second transparent plates to each other to seal said gap; and

inserting a position detection means electrically connected to said first conductive layer of said outer transparent plate and said second conductive layer of said inner transparent plate to interpret a contact position when said first transparent conductor layer is pressed sufficiently against said second transparent conductive layer, wherein the step of roughening includes abrasion roughening.

6. A process according to claim 5, wherein said abrasion roughening includes sand blasting.

7. A process for making a touch panel device comprising:

roughening a first surface of a first transparent plate;

coating said first surface with a first transparent conductive layer;

coating a second surface of a second transparent plate with a second transparent conductive layer;

assembling said first and second transparent plates with said first and second surfaces facing each other separated by a gap;

filling said gap with an insulative liquid;

sealing perimeters of said of first and second transparent plates to each other to seal said gap; and

inserting a position detection means electrically connected to said first conductive layer of said outer transparent plate and said second conductive layer of said inner transparent plate to interpret a contact position when said first transparent conductor layer is pressed sufficiently against said second transparent conductive layer, wherein the step of roughening includes chemical roughening.

8. A process according to claim 7, wherein the step of roughening includes molding.

9. A touch panel input device that utilizes a light pressing force without malfunctioning even when the device as a whole is tilted, said device comprising:

an outer transparent plate;

said outer transparent plate having a first surface and a second surface;

an inner transparent plate;

said inner transparent plate having a third surface and a fourth surface;

said second surface and said third surface facing each other across a gap;

at least one of said second and third surfaces having a roughened surface, said roughened surface having protrusions;

a first transparent conductive layer coating said second surface;

a second transparent conductive layer coating said third surface;

a transparent insulative liquid substantially filling said gap;

a flexible seal interposed between perimeters of said second and third surfaces to seal said gap;

a position detection means electrically connected to said first conductive layer of said outer transparent plate and said second conductive layer of said inner transparent plate to interpret a contact position when said first transparent conductor layer is pressed sufficiently against said second transparent conductive layer, said device when tilted causing the protrusions to establish a light contact engagement that is not a pressing operation.

10. A touch panel input device according to claim 9 wherein;

at least one of said outer transparent plate and said inner transparent plate is glass.

11. A touch panel input device according to claim 9 wherein;

said flexible seal is adhered to said second surface and said third surface.

12. A touch panel input device according to claim 9 wherein;

said outer transparent plate is flexible.

13. A touch panel input device according to claim 9 wherein;

said flexible seal is an ultraviolet-cured pressure sensitive adhesive.