Glare-resistant touch panel

• US 6,572,941 B1
• Filed: 05/18/2000
• Issued: 06/03/2003
• Est. Priority Date: 05/19/1999
• Status: Expired due to Term

• Current Assignee: Gunze Limited
• Original Assignee: Gunze Limited
• Inventors: Hirano, Shunsuke, Murakami, Yukio
• Primary Examiner(s): Thibodeau, Paul
• Assistant Examiner(s): Paulraj, Christopher
• Application Number:
  US09/574,104
• Time in Patent Office: 1,111 Days
• Field of Search: 428/34, 428/212, 428/195, 428/201, 428/500, 428/192, 349/12, 345/173, 345/174, 345/175, 345/176, 345/177, 345/178
• US Class Current: 428/34
• 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 428/24777 Edge feature
• CPC Class Codes: Y10T 428/24851 Intermediate layer is discontinuous or differential
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/31855 Of addition polymer from unsaturated monomers

Abstract

A touch panel is constructed of a top sheet member having a resistive membrane on its inner surface and a base sheet member having a resistive membrane on its inner surface, the top and base sheet members facing each other with dot spacers being located in between. The top sheet member is formed by laminating a PET film, a polarizing film, a ¼λ retardation film, and a light isotropic film in this order from its outer surface. The PET film has a thermal expansion coefficient lower than the other films underneath, such as the polarizing film. Accordingly, the PET film serves to keep the other films of the top sheet member from bulging outward when the temperature rises.

Claims

1. A resistive-membrane touch panel comprising:

a first sheet member having a first resistive membrane on one of main surfaces thereof;

a second sheet member having a second resistive membrane on one of main surfaces thereof, the second sheet member being opposed to the first sheet member with a spacer interposed in between in such a manner that the first resistive membrane and the second resistive membrane face each other with a uniform spacing therebetween; and

a third sheet member being laminated on the outer main surface of the second sheet member,

wherein the second sheet member has a polarizing property, and the third sheet member has a lower thermal expansion coefficient than the second sheet member.

2. The resistive-membrane touch panel of claim 1,

wherein the third sheet member is adhered to the outer main surface of the second sheet member using an adhesive which has a stress relieving ability.

3. The resistive-membrane touch panel of claim 2,

wherein the third sheet member is coated with an acrylic resin on one of main surfaces thereof which is adhered to the outer main surface of the second sheet member.

4. The resistive-membrane touch panel of claim 1,

wherein the third sheet member is less hygroscopic than the second sheet member.

5. The resistive-membrane touch panel of claim 1,

wherein the second sheet member is made by laminating at least two films including a polarizer.

6. The resistive-membrane touch panel of claim 5,

wherein a first quarter wavelength plate is placed outside the first sheet member so as to be approximately parallel to the first sheet member, and the second sheet member includes a second quarter wavelength plate which is laminated nearer to the inner main surface thereof than the polarizer.

7. The resistive-membrane touch panel of claim 6,

wherein an optical axis of the first quarter wavelength plate forms an angle of 45°

with a polarizing axis of the polarizer in a first direction, and an optical axis of the second quarter wavelength plate forms an angle of 45°

with the polarizing axis of the polarizer in a second direction that is opposite to the first direction.

8. The resistive-membrane touch panel of claim 5,

wherein the polarizer is made by sandwiching a polyvinyl alcohol film having a polarizing property between triacetylacetate films, and the third sheet member is made of a material which is less hygroscopic than the triacetylacetate films.

9. The resistive-membrane touch panel of claim 5,

wherein at least part of the spacer is formed along edges of the first and second sheet members in a shape of a picture frame, and

wherein on the inner main surface of the second sheet member are formed a pair of electrodes which are electrically connected to the second resistive membrane and are set facing each other, and a size of the polarizer is such that edges of the polarizer extend beyond inner edges of the at least part of the spacer, at least on two sides where the pair of electrodes are positioned.

10. The resistive-membrane touch panel of claim 1,

wherein the third sheet member is a polyethylene terephthalate film.

11. The resistive-membrane touch panel of claim 1,

wherein at least one of the first resistive membrane and the second resistive membrane has a main surface which is roughened to prevent reflections.

12. The resistive-membrane touch panel of claim 11,

wherein a surface roughness Ra of the rough main surface is in a range of 0.06 μ

m to 3.0 μ

m inclusive.

13. In a heat resistant touch panel for providing signals when at least a predetermined pressure is applied to the panel;

the improvement comprising;

a first sheet member having a first resistive membrane;

a second sheet member having a second resistive membrane operatively connected to the first sheet member, the first resistive membrane is positioned opposite the second resistive membrane at a predetermined spacing distance; and

a third sheet member laminated to the second sheet member, the second sheet member has a polarizing property and the third sheet member has a lower thermal expansion coefficient than the second sheet member whereby a user can apply pressure to force the first and second resistive membranes to contact and provide a signal.

14. The touch panel of claim 13 wherein the third sheet member is adhered to the second sheet member with an adhesive having a stress relieving characteristic.