Acoustic touch position sensor using a low acoustic loss transparent substrate

• US 6,236,391 B1
• Filed: 10/21/1997
• Issued: 05/22/2001
• Est. Priority Date: 01/24/1995
• Status: Expired due to Term

• Current Assignee: Elo Touch Solutions, Inc.
• Original Assignee: Elo Touchsystems Incorporated (Elo Touch Solutions, Inc.)
• Inventors: Tsumura, Masahiro, Kent, Joel
• Primary Examiner(s): Luu, Matthew
• Assistant Examiner(s): Blackman, Anthony J.
• Application Number:
  US08/954,838
• Time in Patent Office: 1,309 Days
• Field of Search: 345/177, 345/176, 345/173, 510/72, 510/69, 178/18.01, 178/18.03, 178/18.04
• 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

An acoustic touch panel or “touch screen” utilizes acoustic waves within a sensor substrate to determine the position of touch. The substrate is made of a temperable glass having an attenuation coefficient of less than or equal to about 0.6 dB/cm as determined at the substrate surface for 5.53 MHz Rayleigh waves as measured by the slope of a plot of amplitude versus distance for a signal through a pair of facing 0.5-inch wide wedge transducers mounted on a sample of the glass type under test having sufficient thickness to support Rayleigh wave propagation. An acoustic touch panel with a tempered low-acoustic-loss glass substrate. This makes possible large tempered acoustic touch panels.

A glass substrate of the touch sensor comprises SiO₂ as the main component with a total content of Na₂O, CaO and MgO of 20% by weight or less and a total content of Al₂O₃, ZrO₂, TiO₂, B₂O₃, Y₂O₃, SnO₂, PbO₂, In₂O₃ and K₂O of 5% by weight or more.

Claims

1. A touch panel provided with a glass substrate as a propagation medium for Rayleigh waves and which is used for detecting the coordinate data on a touching position, wherein the composition of the glass substrate comprises SiO₂ as the main component, comprises at least 1% by weight of Na₂O and comprises additional components that prevent said SiO₂ from forming a regular crystalline lattice by disruption of Si—

O—

Si covalent links, and wherein said added components provide sufficiently strong alternate links through strong ionic bonding, alternate covalent bonding, or steric constraints to produce an attenuation coefficient of less than or equal to about 0.51 dB/cm as determined at the substrate surface for 5.53 MHZ Rayleigh waves as measured by the slope of a plot of amplitude versus distance for a signal through a pair of facing 0.5-inch wide wedge transducers mounted on a sample of the glass type under test having sufficient thickness to support Rayleigh wave propagation.

2. A touch panel provided with a glass substrate as a propagation medium for Rayleigh waves and which is used for detecting the coordinate data on a touching position, wherein the composition of the glass substrate comprises SiO₂ as the main component, at least 1% by weight of Na₂O and the total content of Na₂O, CaO and MgO in said glass substrate is 20% by weight or less.

3. A touch panel as claimed in claim 2, wherein the total content of Al₂O₃, ZrO₂, TiO₂, B₂O₃, Y₂O₃, SnO₂, PbO₂, In₂O₃, and K₂O in said glass substrate is 5% by weight or more.

4. A touch panel according to claim 2, wherein said substrate is laminated to reverse projection screen material.

5. A touch panel according to claim 2, wherein said substrate is curved in profile.

6. The touch panel according to claim 5, wherein said substrate is a glass containing at least about 1% by weight of barium oxide.

7. The touch panel according to claim 5, wherein said substrate is a glass containing at least about 2% by weight of barium oxide.

8. The touch panel according to claim 5, wherein said substrate has the approximate composition (weight % on oxide basis) SiO₂:

69, Na₂O;

8, K₂O;

8, CaO;

7, BaO;

2, ZnO;

4, TiO₂;

1, Sb₂O₃;

1.

9. A touch panel provided with a glass substrate as a propagation medium for Rayleigh waves and which is used for detecting the coordinate data on a touching position, wherein said glass substrate is comprised of SiO₂ as the main component and at least 1% by weight of Na₂O₂ said glass substrate having a higher light transmission than a soda-lime glass in the visible ray region.

10. A touch panel provided with a glass substrate as a propagation medium for Rayleigh waves and which is used for detecting the coordinate data on a touching position, wherein said glass substrate is comprised of SiO₂ as the main component, the content of Na₂O is at least 1% by weight:

the total content of Na₂O, CaO, and MgO is 20% by weight or less; and

the total content of Al₂O₃, ZrO₂, TiO₂, B₂O₃, Y₂O₃, SnO₂, PbO₂, In₂O₃, and K₂O is 5 percent by weight or more, and wherein said substrate comprises a glass having a higher light transmission than a soda-lime glass in the visible ray region.

11. A touch panel as claimed in claim 10 provided with a glass substrate as a propagation medium for Rayleigh waves and which is used for detecting the coordinate data on a touching position, wherein said glass substrate comprises 1 to 17% by weight of the total content of Na₂O, CaO and MgO, and 5 to 20% by weight of the total content of Al₂O₃, ZrO₂, TiO₂, B₂O₃, Y₂O₃, SnO₂, PbO₂, In₂O₃ and K₂O.

12. A touch panel as claimed in claim 10, wherein said substrate has the approximate composition (weight % on oxide basis) SiO₂:

69, Na₂O;

8, K₂O;

8, CaO;

7, BaO;

2, ZnO;

4, TiO₂;

1, Sb₂O₃;

1.

13. In a touch panel system comprising a substrate capable of supporting acoustic waves propagation and means for introducing said waves in said substrate, the improvement comprising said substrate being made of a temperable glass having an attenuation coefficient of less than or equal to about 0.5 dB/cm as determined at the substrate surface for 5.53 MHz Rayleigh waves as measured by the slope of a plot of amplitude versus distance for a signal through a pair of facing 0.5-inch wide wedge transducers mounted on a sample of the glass type under test having sufficient thickness to support Rayleigh wave propagation.

14. A touch panel as claimed in claim 13, wherein the acoustic waves are Rayleigh waves.

15. The touch panel according to claim 13, wherein said glass has a thermal expansion coefficient greater than about 6×

10<sup>−

6</sup>/K before tempering.

16. The touch panel according to claim 13, wherein said substrate is heat-tempered and has a thermal expansion coefficient between about 6×

10<sup>−

6</sup>/K and about 12×

10<sup>−

6</sup>/K before tempering.

17. The touch panel according to claim 16, wherein said substrate is heat-tempered and has a thermal expansion coefficient between about 8×

10<sup>−

6</sup>/K and about 10×

10<sup>−

6</sup>/K before tempering.

18. The touch panel according to claim 13, wherein said attenuation coefficient is equal to or less than about 0.45 dB/cm.

19. The touch panel according to claim 13, wherein said substrate is thermally tempered and has an attenuation coefficient less than or equal to about 0.5 dB/cm.

20. A touch panel according to claim 13, wherein said substrate is comprised of SiO₂ as the main component and the total content of Na₂O, CaO and MgO in said glass substrate is 20% by weight or less.

21. A touch panel as claimed in claim 20, wherein the total content of Al₂O₃, ZrO₂, TiO₂, B₂O₃, Y₂O₃, SnO₂, PbO₂, In₂O₃ and K₂O in said glass substrate is 5% by weight or more.

22. A touch panel as claimed in claim 13, wherein said glass substrate is comprised of SiO₂ as the main component and said glass substrate has a higher light transmission than a soda-lime glass in the visible ray region.

23. A touch panel as claimed in claim 13, wherein said glass substrate is comprised of SiO₂ as the main component, the total content of Na₂O, CaO and MgO is 20% by weight or less and the total content of Al₂O₃, ZrO₂, TiO₂, B₂O₃, Y₂O₃, SnO₂, PbO₂, In₂O₃ and K₂O is 5% by weight or more, and wherein said substrate comprises a glass having a higher light transmission than a soda-lime glass in the visible ray region.

24. A touch panel as claimed in claim 13, wherein said glass substrate comprises 1 to 17% by weight of the total content of Na₂O, CaO and MgO, and 5 to 20% by weight of the total content of Al₂O₃, ZrO₂, TiO₂, B₂O₃, Y₂O₃, SnO₂, PbO₂, In₂O₃ and K₂O.

25. The touch panel according to claim 13, wherein said substrate is a barium-containing glass.

26. The touch panel according to claim 13, wherein said substrate is a glass containing at least about 1% by weight of barium oxide.

27. The touch panel according to claim 13, wherein said substrate is a glass containing at least about 2% by weight of barium oxide.

28. The touch panel according to claim 13, wherein said substrate has the approximate composition (weight % on oxide basis) SiO₂:

69, Na₂O;

4, K₂O;

8, CaO;

7, BaO;

2, ZnO;

4, TiO₂;

1, Sb₂O₃;

1.

29. The touch panel according to claim 13, wherein said substrate is adapted for propagating Rayleigh waves.

30. The touch panel according to claim 13, wherein said substrate is adapted for propagating horizontally polarized shear waves.

31. The touch panel according to claim 13, wherein said substrate is adapted for propagating higher order horizontally polarized shear waves.

32. The touch panel according to claim 13, wherein said substrate is adapted for propagating zeroth order horizontally polarized shear waves.

33. The touch panel according to claim 13, wherein said substrate is adapted for propagating Love waves.

34. The touch panel according to claim 13, wherein said touch sensor comprises:

a substrate having at least one touch surface and being capable of propagating an acoustic wave;

a transducer for producing an acoustic wave along a first axis in said substrate, said first axis being parallel to said surface; and

a first reflecting array having a length and being disposed along said first axis, for reflecting, along said length of said array, a first reflected wave, said first reflected wave being directed along a second axis in said substrate, different from said first axis, and having a component parallel to said surface;

whereby a proximity of an object to said substrate causes a perturbation in the power carried by said first reflected wave.

35. The touch panel according to claim 13, wherein glass frit is present as a reflector material.

36. The touch panel according to claim 13, wherein there is present as a reflector material a reflector ink which is cured at a temperature below the annealing temperature of the glass.

37. The touch panel according to claim 13, wherein said substrate is a lamination of two sheets of glass comprising an inner layer and an outer layer, in which the outer layer has an attenuation coefficient less than or equal to about 0.5 dB/cm.

38. The touch panel according to claim 37, wherein said inner layer is a tempered glass.

39. The touch panel according to claim 37, wherein in said safety glass lamination both the inner layer and the outer layer are tempered glass.

40. The touch panel according to claim 37, wherein the outer layer is comprised of a glass having the approximate composition (weight % on oxide basis) SiO₂:

69.5, Na₂O;

8.1, K₂O;

8.3, CaO;

7.1, BaO;

2.1, ZnO;

4.2, TiO₂;

0.5, Sb₂O₃;

0.5.

41. The touch panel according to claim 37, wherein said outer layer has a thermal expansion coefficient greater than 6×

10<sup>−

6</sup>/K.

42. The touch panel according to claim 37, wherein said inner layer is tempered soda-lime glass.

43. The touch panel according to claim 13, wherein said substrate is generally rectangular in shape, in face view, and has four substantially straight edges, the diagonal dimension of said substrate being greater than 21 inches.

44. A touch panel according to claim 13, wherein said substrate has a coating on said surface to substantially eliminate glare from reflection.

45. A touch panel according to claim 13, wherein said substrate is laminated to reverse projection screen material.

46. A touch panel according to claim 13, wherein said substrate is curved in profile.

47. In a touch sensor system comprising a substrate capable of supporting acoustic waves propagation and means for introducing said waves in said substrate, the improvement comprising said substrate being made of a chemically hardened barium-containing glass having an attenuation coefficient of less than or equal to about 0.5 dB/cm as determined at the substrate surface for 5.53 MHz Rayleigh waves as measured by the slope of a plot of amplitude versus distance for a signal through a pair of facing 0.5-inch wide wedge transducers mounted on a sample of the glass type under test having sufficient thickness to support Rayleigh wave propagation.