Pressure sensitive conductive sheet, method of manufacturing the same, and touch panel using the same

• US 20060170659A1
• Filed: 12/20/2005
• Published: 08/03/2006
• Est. Priority Date: 01/31/2005
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Tanabe, Koji, Yamamoto, Yasutaka
• Granted Patent: US 7,595,790 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0414 using force sensing means to determine a position
• 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: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles

Abstract

A pressure sensitive conductive sheet is provided by having a plurality of ferromagnetic conductive particles dispersed in a transparent elastic member joined together and linearly aligned with the thickness direction thereby forming a linear aggregate and then having the linear aggregate segmented into a plurality conductive elements, held linearly aligned with the thickness direction, with predetermined gaps formed therebetween. Further, a touch panel having good transparency and allowing stabilized operation is provided by interposing the pressure sensitive conductive sheet between an upper conductive layer on the lower face of an upper substrate and a lower conductive layer on the upper face of a lower substrate.

Claims

1. A pressure sensitive conductive sheet comprising:

a transparent elastic member; and

a plurality of ferromagnetic conductive particles dispersed in the elastic member, wherein

the plurality of conductive particles form a linear aggregate having a plurality of conductive particles joined together and linearly aligned with a parallel direction to a surface of the elastic member,

the linear aggregate is segmented into a configuration of a plurality of conductive elements, held linearly aligned with the parallel direction to a surface of the elastic member, with predetermined gaps formed therebetween, and

a plurality of configurations identical to the configuration of a plurality of conductive elements are disposed at predetermined intervals in a vertical direction to a surface of the elastic member.

2. The pressure sensitive conductive sheet according to claim 1, wherein the additive rates of the conductive particles to the elastic member are between 0.0001 to 1% by volume.

5. A touch panel comprising:

a transparent upper substrate having an upper conductive layer formed on its lower face;

a transparent lower substrate having a lower conductive layer, opposed to the upper conductive layer across a predetermined space, formed on its upper face; and

the pressure sensitive conductive sheet set forth in claim 1 interposed between the upper substrate and the lower substrate.

3. A method of manufacturing a pressure sensitive conductive sheet comprising the steps of:

applying a magnetic field to a transparent elastic member with a plurality of ferromagnetic conductive particles dispersed therein in a parallel direction to a surface of the elastic member for causing the plurality of conductive particles to be joined together to thereby form a linear aggregate;

curing the elastic member; and

swelling the elastic member with use of a swelling liquid such that the linear aggregate is segmented into a plurality of conductive elements with predetermined gaps formed therebetween.

4. The method of manufacturing a pressure sensitive conductive sheet according to claim 3, wherein a rate of volume swelling of elastic member with use of a swelling liquid is set at 4 to 100% by volume.