Touch panel with high operability in low temperature environments

• US 6,570,707 B1
• Filed: 11/08/2000
• Issued: 05/27/2003
• Est. Priority Date: 11/10/1999
• Status: Expired due to Term

• Current Assignee: Gunze Limited
• Original Assignee: Gunze Limited
• Inventors: Hirano, Shunsuke, Murakami, Yukio
• Primary Examiner(s): Chang, Audrey
• Assistant Examiner(s): Curtis, Craig
• Application Number:
  US09/708,879
• Time in Patent Office: 930 Days
• Field of Search: 359/497, 250/225, 345/87, 345/156, 345/173, 349/12, 349/23, 349/58, 349/62, 349/96, 349/149, 349/150, 349/176, 349/199, 349/201
• US Class Current: 359/489.07
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

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 bulge-resistant film, a polarizing plate, a quarter wavelength plate, and a light isotropic film in this order from above. The base sheet member is constructed of a glass sheet and a reinforcement film whose thermal linear expansion coefficient is almost the same as the thermal linear expansion coefficient of the polarizing plate or the quarter wavelength plate included in the top sheet member, the reinforcement film being adhered to the lower surface of the glass sheet.

Claims

1. A resistive-membrane touch panel comprising:

a first sheet member having a first resistive membrane on a main surface thereof;

a second sheet member that is flexible and has a second resistive membrane on a main surface thereof, the second sheet member being opposed to the first sheet member with a spacer in between so that the second resistive membrane and the first resistive membrane face each other with a certain spacing therebetween; and

a third sheet member that is provided on at least a part of another main surface of the first sheet member that does not face the second sheet member,

wherein the third sheet member has a higher thermal linear expansion coefficient than the first sheet member.

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

wherein the second sheet member includes a polarizing plate whose thermal linear expansion coefficient is higher than a thermal linear expansion coefficient of the first sheet member, and the thermal linear expansion coefficient of the third sheet member is almost the same as the thermal linear expansion coefficient of the polarizing plate.

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

wherein the first sheet member is a glass sheet whose thickness is at least 0.4 mm but is below 1.85 mm.

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

wherein the third sheet member is made of at least one resin film selected from the group consisting of triacetylacetate film, polycarbonate film, polyarylate film, polysulfone film, polyether sulfone film, polyvinyl alcohol film, norbornene resin film, and olefin resin film.

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

wherein a thickness of the third sheet member is in the range of 50 μ

m to 200 μ

m inclusive.

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

wherein the second sheet member comprises a plurality of sheet members including a polarizing plate and a first quarter wavelength plate, the first quarter wavelength plate being placed nearer to the spacing than the polarizing plate, and

a second quarter wavelength plate is placed on an opposite side of the first sheet member to the second sheet member.

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

wherein the third sheet member serves as the second quarter wavelength plate.

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

wherein the third sheet member is made of at least one resin film selected from the group consisting of polycarbonate film, polyarylate film, polysulfone film, polyvinyl alcohol film, norbornene resin film, and olefin resin film.

9. 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 polarizing plate 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 polarizing plate in a second direction that is opposite to the first direction.

10. The resistive-membrane touch panel of claim 1 further comprising:

a fourth sheet member that is provided on an outer main surface of the second sheet member,

wherein the second sheet member has a polarization property and the fourth sheet member has a lower thermal linear expansion coefficient than the second sheet member.

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

wherein the fourth sheet member is made of a polyethylene terephthalate film.

12. A resistive-membrane touch panel comprising:

a first transparent member having a first thermal linear expansion coefficient and a respective length and width greater than its thickness with a first resistive portion on a first surface;

a second transparent member extending across the first transparent member and spaced a predetermined operative distance from the first transparent member, a second resistive portion on a first surface of the second transparent member opposite the first surface of the first transparent member, the second transparent member being flexible to permit a user to exert a force on the second transparent member to cause the second resistive portion to close the operative distance and contact the first resistive portion; and

a third member operatively connected to the first transparent member and having a sufficient thickness and a second coefficient of thermal linear expansion different from the first thermal linear expansion coefficient across an approximate temperature range of −

20°

to 40°

Celsius to substantially offset any thermal forces which would bend the first transparent member to substantially vary the operative distance between the first and second transparent member.

13. The resistive-membrane touch panel of claim 12, wherein the third member is operatively connected to a second surface of the first transparent member.

14. The resistive-membrane touch panel of claim 12, wherein the second transparent member has a fourth member operatively connected to the second transparent member with a third coefficient of thermal linear expansion coefficient higher than the thermal linear expansion coefficient of the second transparent member across the approximate temperature range of −

20°

to 40°

Celsius to substantially offset any thermal forces which would bend the second transparent member to substantially vary the operative distance between the first and second transparent members.