Surface acoustic wave touchscreen with housing seal

• US 5,784,054 A
• Filed: 03/22/1996
• Issued: 07/21/1998
• Est. Priority Date: 03/22/1996
• Status: Expired due to Term

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Elo Touchsystems Incorporated (Elo Touch Solutions, Inc.)
• Inventors: Jones, Richard A., Lewis, Michael L., Benitez, Susan P., Phares, Robert C., Asher, Jeffrey W., Kent, Joel C., Armstrong, Donald B.
• Primary Examiner(s): BRIER, JEFFERY A
• Application Number:
  US08/621,127
• Time in Patent Office: 851 Days
• Field of Search: 345/177, 277/654, 277/630, 277/637
• US Class Current: 345/177
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate

Abstract

An effective seal for protecting a touchscreen and associated electronics from liquid infiltration, the seal being placed between the housing and the surface of the touchscreen and configured to surround the useful touchscreen area. The seal is preferably formed of a closed cell foam covered on the surface which contacts the touchscreen surface with a liquid impervious barrier, or an expanded polymer such as expanded PTFE. The seal may be secured to the bezel edge by a transfer adhesive coating applied to the bezel edge, except for a relatively thin edge strip along the inner edge of the bezel end, so that substantially no adhesive is present on a free surface of the seal body proximate to the window aperture of the bezel. Preferably, a smooth surface is provided for adhering the seal body to the bezel. The seal body may be compressed between the bezel and touchscreen surface to effect a seal.

Claims

1. A seal system for a surface acoustic wave touchscreen including a screen having a touch surface disposed to be selectively touched and a housing mounting the screen, the housing including at least one open window disposed proximate and surrounding the touch surface of the screen and including a housing end surface having two sides thereto and an inner surface, disposed proximate to and surrounding the open window and spaced from the touchscreen touch surface by a seal space, and a seal disposed in the seal space between the housing end surface and the touchscreen surface proximate thereto for filling the seal space, said seal comprising:

(a) sealing body having a predetermined thickness and width, said predetermined thickness being at least sufficient to fill said seal space between the housing end surface and the touchscreen surface disposed proximate thereto, said sealing body having a liquid impervious barrier and allowing transmission of at least a portion of a surface acoustic wave adjacent thereto;

(b) said liquid impervious barrier covering at least said width of said sealing body so as to provide an outer covering surface;

(c) said outer covering surface being disposed adjacent the touchscreen surface when said sealing body is disposed in said seal space;

(d) an adhesive, for adhering said sealing body to said housing inner surface, having a width smaller than said width of said sealing body, so that said adhesive may be sandwiched between said sealing body and said housing inner surface.

2. The seal system of claim 1, wherein housing end surface has a width, said predetermined width of said sealing body being at least equal to said width of said housing end surface.

3. The seal system of claim 2, wherein said predetermined width of said sealing body is wider than said width of said housing end surface and when disposed in said seal space covering at least said width of said housing end surface and extending out beyond same to at least one said side of said housing end surface.

4. The seal system of claim 3, wherein said predetermined width of said sealing body and the positioning thereof is such that said sealing body extends out beyond each said side of said housing end surface.

5. The seal system of claim 1, wherein said sealing body is provided with a second outer surface disposed proximate the housing end surface when said sealing body is disposed in said seal space.

6. The seal system of claim 5, wherein said second outer surface is secured to said housing end surface by a transfer adhesive.

7. The seal system of claim 6, wherein housing end surface has a width, said transfer adhesive being applied to almost the full width of said housing end surface except for a relatively thin path proximate an inner surface of said end surface thereof.

8. The seal system of claim 1, wherein at least said sealing body comprises a closed cell foam.

9. The seal system of claim 1, wherein a bulk of said sealing body comprises a closed cell polyolefin foam material.

10. The seal system of claim 1, wherein said sealing body comprises expanded PTFE.

11. The seal system of claim 1, wherein said sealing body is provided as a continuous length strip.

12. The seal system of claim 1, wherein said seal body is positioned between said housing end surface and said touchscreen and compressed between said housing and said touchscreen surface.

13. The seal system of claim 12, wherein said seal body is compressed by about 50% of its free volume.

14. The touchscreen system of claim 1, wherein said seal space is not substantially interior to or otherwise further radial to said window of said housing means, said space location avoiding puddle trap formation.

15. The touchscreen system of claim 1, wherein said seal body extends at least to an inner edge of said window.

16. The touchscreen system of claim 1, further comprising computational means to ignore x and/or y touch coordinates of an acoustic wave perturbation outside of the coordinates of said open window.

17. The touchscreen system of claim 1, further comprising a controller for determining a touch location and adaptively filtering an acoustic attenuation of seal sealing body.

18. The touchscreen according to claim 1, further comprising reflective arrays disposed parallel to sealing body, for deflecting acoustic energy across said touchscreen surface, said reflective arrays having a limited length to reflect acoustic energy along axes within areas bounded by said sealing body.

19. A surface acoustic wave touchscreen system comprising:

(a) a touchscreen having a touch surface;

(b) a housing, including a bezel having an aperture through which said touchscreen surface may be touched, said housing being for mounting said touchscreen;

(c) said bezel including an end surface spaced from said touchscreen touch surface by a seal space, said end surface not including a channel;

(d) a seal strip disposed in and filling said seal space; and

(e) an adhesive, disposed essentially between and adhering said seal strip to said end surface, without an exposed portion proximate to said aperture.

20. The touchscreen of claim 19, wherein said seal strip comprises a body of closed cell foam sheathed on at least one surface by a water impervious film.

21. The touchscreen of claim 19, wherein said seal strip comprises a body of closed cell polyolefin foam sheathed on at least one surface by a water impervious film.

22. The touchscreen of claim 19, wherein said seal strip comprises a body of expanded PTFE.

23. The touchscreen system of claim 19, wherein said seal strip is of a predetermined width and said bezel end surface is of a width at least equal to said predetermined width of said seal strip.

24. The touchscreen system of claim 19, wherein said seal strip has a predetermined width and said bezel end surface has a width at most equal to said predetermined width of said seal strip.

25. The touchscreen system of claim 24, wherein said predetermined width of said seal strip is wider than said width of said bezel end surface and a positioning of said seal strip is such that said seal strip extends out beyond each side of said bezel end surface.

26. The touchscreen system of claim 25, wherein said transfer adhesive is applied to said end surface of said bezel and said seal strip is secured to said transfer adhesive by applying a pressure therebetween, said seal strip having a water impervious barrier disposed adjacent to said touchscreen surface.

27. The touchscreen system according to claim 26, wherein said seal strip further comprises a second water impervious barrier disposed adjacent said contact adhesive.

28. A method of providing a seal between an end surface of a bezel and an open touchscreen touch surface, comprising:

(a) fabricating a seal strip with a body of closed cell foam having at least one surface of said body with a water impervious barrier;

(b) positioning the seal strip between an end surface of the bezel and a touch surface of the touchscreen, defining an open area, so that the water impervious barrier is disposed against the touch surface of the touchscreen; and

(c) adhering the seal strip to the end surface of the bezel with an adhesive, disposed essentially between the seal strip and the end surface, without an exposed portion proximate to the open area.

29. The method according to claim 28, further comprising the step of providing a second water impervious barrier on said seal strip, disposed adjacent the bezel end surface.

30. The method of claim 28, further comprising the step of attaching the seal strip to the bezel end surface with a transfer adhesive.

31. The method of claim 28, further comprising the step of fabricating the seal strip to a width wider than the width of said bezel end surface and applying the seal strip to the bezel end surface so as to extend beyond the bezel end surface width on each side.

32. The method of claim 31, further comprising the step of applying the seal strip to the bezel end surface as a continuous strip, completely around said bezel end surface.

33. The method of claim 31, further comprising the step of applying the seal strip to the bezel end surface as a continuous strip, disposed on a lower portion of the bezel end surface.

34. The method of claim 28, further comprising the step of ignoring any x and/or y acoustic wave perturbation coordinates outside of the coordinates of the open area of the touchscreen touch surface.

35. The method of claim 28, further comprising the step of adaptively filtering an acoustic attenuation of seal sealing body.

36. The method of claim 28, further comprising the step of limiting a location of reflective arrays provided on the touchscreen to reflect acoustic energy along axes within the open area bounded by the tape.