Tensioned touch panel and method of making same

• US 20050241929A1
• Filed: 04/29/2004
• Published: 11/03/2005
• Est. Priority Date: 04/29/2004
• Status: Active Grant

• Current Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Smart Technologies ULC (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Butmir, Amir, Auger, Paul Anthony
• Granted Patent: US 7,687,736 B2
• Time in Patent Office: Days
• US Class Current: 200/512
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• 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 29/49002 Electrical device making
• CPC Class Codes: Y10T 29/49105 Switch making
• CPC Class Codes: Y10T 29/49117 Conductor or circuit manufacturing
• CPC Class Codes: Y10T 29/49128 Assembling formed circuit to base
• CPC Class Codes: Y10T 29/49155 Manufacturing circuit on or in base

Abstract

A tensioned touch panel includes a support structure having a substrate with a generally planer conductive surface disposed thereon and an insulating spacer generally about the periphery of the substrate. A pretensioned conductive member overlies the support structure. The spacer separates the conductive membrane and the conductive surface thereby to define an air gap therebetween. A conductive membrane is secured to the support structure under sufficient tension to inhibit slack from developing in the conductive membrane as a result of changes in environmental conditions. A method of assembling a tensioned touch panel is also provided.

Claims

1. A method of assembling a touch panel including a support structure and a conductive membrane, said support structure having a conductive surface and a peripheral insulating spacer about said conductive surface, said conductive membrane overlying said support structure with said spacer separating said conductive membrane and said conductive surface thereby to define an air gap therebetween, said method comprising:

pretensioning the conductive membrane; and

securing the tensioned conductive membrane to the support structure.

2. The method of claim 1 wherein said pretensioning is selected to compensate for at least one of the coefficient of thermal expansion and the coefficient of hydroscopic or hygroscopic expansion of said conductive membrane over a variety of environmental conditions.

3. The method of claim 2 wherein said pretensioning is selected to compensate for both the coefficients of thermal expansion and hydroscopic or hygroscopic expansion of said conductive membrane over a variety of temperature and humidity conditions.

4. The method of claim 3 wherein said conductive membrane is bonded to said support structure via an adhesive.

5. The method of claim 4 wherein said adhesive is an ultraviolet curing adhesive.

6. The method of claim 4 wherein said adhesive is a cyanoacrylate adhesive.

7. The method of claim 3 wherein said conductive membrane is adhered to said spacer.

8. The method of claim 7 wherein said adhesive is an ultraviolet curing adhesive.

9. The method of claim 7 wherein said adhesive is a cyanoacrylate adhesive.

10. The method of claim 3 wherein said support structure includes a substrate having a generally planar surface on which said conductive surface is disposed and wherein said spacer is generally continuous and overlies the peripheral region of said planar surface thereby to surround said conductive surface.

11. The method of claim 10 wherein said spacer is a rail overlying said peripheral region and wherein said conductive membrane is adhered directly to said rail.

12. The method of claim 10 wherein said spacer is a rail about the periphery of said substrate, said rail being generally L-shaped in side section and including one arm portion disposed on the peripheral region of said planar surface and another arm portion abutting the sides of said substrate, said conductive membrane being adhered directly to said rail.

13. The method of claim 10 wherein said spacer is a rail about the periphery of said substrate, said rail being generally C-shaped in side section and including one arm portion disposed on the peripheral region of said planar surface, another arm portion disposed on an opposed surface of said substrate and a bight joining said arm portions and abutting the sides of said substrate, said conductive membrane being adhered to at least one of said rail and opposed surface.

14. The method of claim 13 wherein said conductive membrane is adhered to said rail.

15. The method of claim 13 wherein said conductive membrane is adhered to said opposed surface.

16. The method of claim 3 wherein during said pretensioning, said conductive membrane is subjected to stress at a level below the yield point of said conductive membrane and below a level at which said conductive membrane exhibits significant creep.

17. The method of claim 16 wherein during said pretensioning, said conductive membrane is subjected to stress in the range of from about 1000 to 1500 psi.

18. A tensioned touch panel comprising:

a support structure including a substrate having a generally planar conductive surface disposed thereon and an insulating spacer generally about the periphery of said substrate; and

a pretensioned conductive membrane overlying said support structure, said spacer separating said conductive membrane and said conductive surface thereby to define an air gap therebetween, said conductive membrane being secured to said support structure under sufficient tension to inhibit slack from developing in said conductive membrane as a result of changes in environmental conditions.

19. A tensioned touch panel according to claim 18 wherein said conductive membrane is subjected to stress at a level selected to compensate for the coefficient of thermal and hydroscopic or hygroscopic expansion of said conductive membrane over a variety of temperature and humidity conditions prior to being secured to said support structure.

20. A tensioned touch panel according to claim 19 wherein said stress level is below the yield point of said conductive membrane and below a level at which said conductive membrane exhibits significant creep.

21. A tensioned touch panel according to claim 20 wherein said stress level is in the range of from about 1000 to 1500 psi.

22. A tensioned touch panel according to claim 20 wherein said conductive membrane is adhered to said support structure.

23. A tensioned touch panel according to claim 22 wherein said adhesive is an ultraviolet curing adhesive.

24. A tensioned touch panel according to claim 22 wherein said adhesive is a cyanoacrylate adhesive.

25. A tensioned touch panel according to claim 22 wherein said spacer is a generally continuous rail about the periphery of said substrate.

26. A tensioned touch panel according to claim 25 wherein said rail overlies a peripheral region of said substrate surrounding said conductive surface, said conductive membrane being adhered directly to said rail.

27. A tensioned touch panel according to claim 25 wherein said rail is generally L-shaped in side section and includes one arm portion overlying said peripheral region and another arm portion abutting the sides of said substrate, said conductive member being adhered directly to said rail.

28. A tensioned touch panel according to claim 25 wherein said rail is generally C-shaped in side section and includes one arm portion overlying said peripheral region, another arm portion overlying an opposed surface of said substrate and a bight joining said arm portions and abutting the sides of said substrate, said conductive member being adhered to at least one of said rail and opposed surface.

29. A tensioned touch panel according to claim 28 wherein said conductive membrane is adhered to said rail.

30. A tensioned touch panel according to claim 28 wherein said conductive membrane is adhered to said opposed surface.

31. A tensioned touch panel according to claim 20 wherein said conductive membrane includes a film and a conductive layer on said film, said conductive layer facing said conductive surface.

32. A tensioned touch panel according to claim 31 wherein said conductive layer covers a portion of a major surface of said film defining a peripheral margin, said peripheral margin corresponding generally in shape to said spacer.

33. A tensioned touch panel according to claim 31 wherein said conductive layer covers the entirety of a major surface of said film.

34. A tensioned touch panel comprising:

a support structure having a conductive surface disposed thereon; and

a conductive membrane overlying said conductive surface in spaced apart relation, said conductive membrane being permanently secured to said substrate while under tension.

35. A tensioned touch panel according to claim 34 wherein said conductive membrane is adhered to said support structure.

36. A tensioned touch panel according to claim 35 wherein said adhesive is an ultraviolet curing adhesive.

37. A tensioned touch panel according to claim 35 wherein said adhesive is a cyanoacrylate adhesive.

38. A tensioned touch panel according to claim 35 wherein said conductive membrane is subjected to stress at a level selected to compensate for the coefficient of thermal and hydroscopic or hygroscopic expansion of said conductive membrane over a variety of temperature and humidity conditions.

39. A tensioned touch panel according to claim 38 wherein said stress level is below the yield point of said conductive membrane and below a level at which said conductive membrane exhibits significant creep.

40. A tensioned touch panel according to claim 39 wherein said stress level is in the range of from about 1000 to 1500 psi.