Acoustic touchscreen constructed directly on a cathode ray tube

• US 6,225,985 B1
• Filed: 03/26/1999
• Issued: 05/01/2001
• Est. Priority Date: 03/26/1999
• Status: Expired due to Fees

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Elo Touchsystems Incorporated (Elo Touch Solutions, Inc.)
• Inventors: Armstrong, Donald B., Kent, Joel, Roney, James
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Laneau, Ronald
• Application Number:
  US09/277,571
• Time in Patent Office: 767 Days
• Field of Search: 345/177, 345/173, 367/153, 367/154, 367/155
• US Class Current: 345/177
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate

Abstract

A touchscreen is constructed directly on the glass surface of a cathode ray tube (CRT). To solve the problem of insufficient space between the CRT'"'"'s bezel and frontal region to accommodate the transducers for the touchscreen, the transducers are moved away from the frontal region, to the highly curved shoulder region of the CRT. To preserve acoustic signal strength, the positioning of the transducers is chosen to take advantage of the fact that an acoustic wave on a non-Euclidean surface travels along a geodesic path. Allowance is also made for the acoustic lens and prism effect of the corner regions of the CRT, where the transducer may be located.

Claims

1. An acoustic touchscreen constructed directly on a CRT, comprising:

(a) a CRT comprising

(i) a substantially rectangular frontal region having four corners and

(ii) a shoulder region below the frontal region, including four corner regions at the confluences of the shoulder region and the corners of the frontal region;

(b) a first transducer acoustically coupled to the surface of the CRT and capable of generating an acoustic signal thereon;

(c) a first linear array of partially acoustically reflective elements associated with the first transducer, the first linear array being disposed on the frontal region, being capable of deflecting the acoustic signal across the frontal region, and having a longitudinal array axis;

(d) a second transducer acoustically coupled to the surface of the CRT and capable of detecting the acoustic signal after the acoustic signal has traveled across the frontal region, together with perturbations thereto caused by a touch on the frontal region; and

(e) a second linear array of partially acoustically reflective elements associated with the second transducer, the second linear array being disposed on the frontal region, being capable of deflecting the acoustic signal towards the second transducer after the acoustic signal has traveled across the frontal region, and having a longitudinal array axis;

the first and second transducers being located on the shoulder region, each positioned on and aimed along the geodesic defined by the longitudinal array axis of the respective associated linear array.

2. An acoustic touchscreen according to claim 1, wherein at least one of the first and second transducers is a wedge transducer.

3. An acoustic touchscreen according to claim 1, wherein the frontal region of the CRT comprises borosilicate glass or barium-containing glass.

4. An acoustic touchscreen according to claim 1, wherein at least one geodesic passes through a corner region.

5. An acoustic touchscreen according to claim 4, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region is a diverging transducer.

6. An acoustic touchscreen according to claim 4, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region is a wedge transducer having a piezoelectric element having a width no greater than 6 mm.

7. An acoustic touchscreen according to claim 4, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region is a wedge transducer having a piezoelectric element having a width no greater than 4 mm.

8. An acoustic touchscreen according to claim 4, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region has a bottom surface curved to mate with the curvature of the surface of the CRT at the location where the transducer is acoustically coupled to the surface of the CRT.

9. An acoustic touchscreen according to claim 4, wherein the frontal region of the CRT comprises borosilicate glass or barium-containing glass.

10. An acoustic touchscreen according to claim 1, wherein the frontal region of the CRT is substantially planar.

11. An acoustic touchscreen according to claim 1, wherein the reflective elements comprise a polymer containing a dense filler selected from the group consisting of powdered tungsten, tungsten trioxide, tungsten carbide, calcium carbonate, lead oxide, zinc oxide, barium sulfate, zinc sulfide, silicon dioxide, and combinations thereof.

12. An acoustic touchscreen constructed directly on a CRT, comprising:

(a) a CRT comprising;

(i) a substantially rectangular frontal region having four corners and

(ii) a shoulder region below the frontal region, including four corner regions at the confluences of the shoulder region and the corners of the frontal region;

(b) first and second transducers, each acoustically coupled to the surface of the CRT and capable of generating respective first and second acoustic signals on the surface of the CRT;

(c) first and second linear arrays of partially acoustically reflective elements associated with the first and second transducers respectively, for deflecting the first and second acoustic signals, respectively, across the frontal region;

each of the first and second linear arrays having a respective longitudinal array axis;

the first linear array being disposed along a first edge of the frontal region and the second linear array being disposed along a second edge of the frontal region substantially orthogonal to the first edge;

(d) third and fourth transducers, each acoustically coupled to the surface of the CRT;

the third transducer being capable of detecting the first acoustic signal after the first acoustic signal has traveled across the frontal region, together with perturbations thereto caused by a touch on the frontal region;

the fourth transducer being capable of detecting the second acoustic signal after the second acoustic signal has traveled across the frontal region, together with perturbations thereto caused by a touch on the frontal region; and

(e) third and fourth linear arrays of partially acoustically reflective elements associated with the third and fourth transducers respectively, for deflecting the first and second acoustic signals towards the third and fourth transducers, respectively, after the first and second acoustic signals have traveled across the frontal region;

each of the third and fourth linear arrays having a respective longitudinal array axis;

the third linear array being disposed along a third edge of the frontal region opposite the first edge thereof and the fourth linear array being disposed along a fourth edge of the frontal region opposite the second edge thereof;

the first, second, third and fourth transducers being located on the shoulder region, positioned on and aimed along the geodesic defined by the longitudinal array axis of the respective associated linear array.

13. An acoustic touchscreen according to claim 12, wherein at least one of the first, second, third, and fourth transducers is a wedge transducer.

14. An acoustic touchscreen according to claim 12, wherein the frontal region of the CRT comprises borosilicate glass or barium-containing glass.

15. An acoustic touchscreen according to claim 12, wherein at least one geodesic passes through a corner region.

16. An acoustic touchscreen according to claim 15, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region is a diverging transducer.

17. An acoustic touchscreen according to claim 15, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region is a wedge transducer having a piezoelectric element having a width no greater than 6 mm.

18. An acoustic touchscreen according to claim 15, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region is a wedge transducer having a piezoelectric element having a width no greater than 4 mm.

19. An acoustic touchscreen according to claim 15, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region has a bottom surface curved to mate with the curvature of the surface of the CRT at the location where the transducer is acoustically coupled to the surface of the CRT.

20. An acoustic touchscreen according to claim 15, wherein the frontal region of the CRT comprises borosilicate glass or barium-containing glass.

21. An acoustic touchscreen according to claim 12, wherein the frontal region of the CRT is substantially planar.

22. A method of constructing a touchscreen directly on a CRT, comprising the steps of:

(a) providing a CRT comprising

(i) a substantially rectangular frontal region having four corners and

(ii) a shoulder region below the frontal region, including four corner regions at the confluences of the shoulder region and the corners of the frontal region;

(b) providing plural transducers;

(c) forming, on the frontal region, plural linear arrays of partially acoustically reflective elements, each linear array associated with a respective one of the plural transducers, each linear array having a respective longitudinal array axis;

(d) determining, for each linear array, the geodesic defined by the respective longitudinal array axis; and

(e) for each geodesic so determined, acoustically coupling the respective associated transducer to the surface of the CRT on the shoulder region, positioned on and aimed along the geodesic.

23. A method according to claim 22, wherein at least one of the geodesics determined in step (d) is determined by stretching, on the surface of the CRT, a length of flexible material along a longitudinal array axis and following the curvature of the surface from the frontal region to the shoulder region.

24. A method according to claim 22, wherein at least one of the plural transducers is acoustically coupled to the surface of the CRT with a UV-curable adhesive.

25. An acoustic touchscreen according to claim 22, wherein at least one of the geodesics determined in step (d) passes through a corner region.

26. A method according to claim 25, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region is a diverging transducer.

27. A method according to claim 25, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region is a wedge transducer having a piezoelectric element having a width no greater than 6 mm.

28. A method according to claim 25, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region is a wedge transducer having a piezoelectric element having a width no greater than 4 mm.

29. A method according to claim 25, wherein the transducer positioned on and aimed along the at least one geodesic passing through a corner region has a bottom surface curved to mate with the curvature of the surface of the CRT at the location where the transducer is acoustically coupled to the surface of the CRT.

30. A method according to claim 25, wherein the frontal region of the CRT comprises borosilicate glass or barium-containing glass.

31. A method according to claim 22, wherein the frontal region of the CRT is substantially planar.

32. A method of situating a transducer for an acoustic touchscreen constructed directly on a CRT, comprising the steps of:

(a) providing a CRT comprising

(i) a substantially rectangular frontal region having four corners and

(ii) a shoulder region below the frontal region, including four corner regions at the confluences of the shoulder region and the corners of the frontal region;

the CRT further having formed thereon a linear array of partially acoustically reflective elements, the linear array having a longitudinal array axis;

(b) determining the geodesic defined by the longitudinal array axis;

(c) providing a transducer;

(d) positioning the transducer on and aimed along the geodesic, on the surface of the CRT on the shoulder region; and

(e) acoustically coupling the transducer to the surface of the CRT, positioned and aimed according to the preceding step.

33. A method according to claim 32, wherein the geodesic is determined by stretching on the surface of the CRT, a length of flexible material along a longitudinal array axis and following the curvature of the surface from the frontal region to the shoulder region.

34. A method according to claim 32, wherein the transducer is acoustically coupled to the surface of the CRT with a UV-curable adhesive.

35. An acoustic touchscreen according to claim 32, wherein the geodesics determined in step (b) passes through a corner region.

36. A method according to claim 35, wherein the transducer positioned on and aimed along the geodesic passing through a corner region is a diverging transducer.

37. A method according to claim 35, wherein the transducer positioned on and aimed along the geodesic passing through a corner region is a wedge transducer having a piezoelectric element having a width no greater than 6 mm.

38. A method according to claim 35, wherein the transducer positioned on and aimed along the geodesic passing through a corner region is a wedge transducer having a piezoelectric element having a width no greater than 4 mm.

39. A method according to claim 35, wherein the transducer positioned on and aimed along the geodesic passing through a corner region has a bottom surface curved to mate with the curvature of the surface of the CRT at the location where the transducer is acoustically coupled to the surface of the CRT.

40. A method according to claim 35, wherein the frontal region of the CRT comprises borosilicate glass or barium-containing glass.

41. A method according to claim 32, wherein the frontal region of the CRT is substantially planar.

42. A method according to claim 32, further comprising the step of modifying the topography of the bottom surface of the transducer to mate with the curvature of the surface of the CRT at the location at which the transducer is acoustically coupled to the surface of the CRT, prior to acoustically coupling the transducer to the surface of the CRT.