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Claims  |
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What is claimed is:
1. A touch sensor comprising:
a substrate having at least one touch surface and being capable of
propagating an acoustic wave having a horizontal shear-type component
substantially parallel to said surface, having a nonuniform volumetric
energy density along a vertical axis normal to said surface and having
energy at said surface;
a transducer for producing an acoustic wave having a longitudinal component
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, as a first
reflected wave, portions of said wave having a longitudinal component,
said first reflected wave having a horizontal shear-type component
substantially parallel to said surface, having a nonuniform volumetric
energy density along a vertical axis normal to said surface, and having
energy at said surface, said first reflected wave being directed along a
second axis in said substrate, different than 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.
2. The touch sensor according to claim 1, further comprising a second
reflecting array spaced from said first reflecting array across said
substrate along said second axis of said first reflected wave, for
reflecting said first reflected wave as a wave having a longitudinal
component along a third axis.
3. The touch sensor according to claim 1, further comprising a reflecting
member spaced from said first reflecting array across said substrate along
said first axis, for reflecting said first reflected wave as a second
reflected wave toward said first reflecting array along a fourth axis.
4. The touch sensor according to claim 3, wherein said fourth axis is
antiparallel with said second axis, and said first reflecting array
reflects said second reflected wave from said fourth axis to a fifth axis,
antiparallel with said first axis as a wave having a longitudinal
component.
5. The touch sensor according to claim 1, further comprising a transducer
for detecting a perturbation in said first reflected wave.
6. The touch sensor according to claim 1, wherein a temporal characteristic
of said perturbation corresponds to a position of said object in proximity
to said substrate.
7. The touch sensor according to claim 1, further comprising:
a second transducer for producing an acoustic wave having a longitudinal
component along a sixth axis in said substrate, said sixth axis being
parallel to said surface; and
a second reflecting array having a length and being disposed along said
sixth axis, for reflecting, along said length of said array, as a third
reflected wave, portions of said wave having a longitudinal component,
said third reflected wave having a horizontal shear-type component
substantially parallel to said surface, having a nonuniform volumetric
energy density along a vertical axis normal to said surface, and having
energy at said surface, said third reflected wave being directed along a
seventh axis in said substrate, different than said sixth axis, and being
parallel to said surface;
a proximity of an object to said substrate cause a perturbation in the
power carried by said third reflected wave, so that said proximity causes
a perturbation of waves travelling along both said second axis and said
seventh axis.
8. The touch sensor according to claim 7, further comprising means for
detecting a perturbation of said waves travelling along said second axis
and said seventh axis.
9. The touch sensor according to claim 1, wherein said wave having a
longitudinal component is a Rayleigh-type wave.
10. The touch sensor according to claim 1, wherein said wave having a
longitudinal component is a Lamb-type wave.
11. The touch sensor according to claim 1, wherein said first reflective
array comprises a diffraction grating of acoustic scattering elements,
separating modes of said horizontal shear-type component substantially
parallel to said surface, having a nonuniform volumetric energy density
along a vertical axis normal to said surface and having energy at said
surface, by differences in phase velocity.
12. The touch sensor according to claim 1, wherein said first reflected
wave is a horizontally polarized shear wave of order greater than zero.
13. The touch sensor according to claim 1, wherein said first reflected
wave is a horizontally polarized shear wave of order 4.
14. The touch sensor according to claim 1, wherein said first reflected
wave is a Love wave.
15. The touch sensor according to claim 1, wherein said substrate has a
thickness greater than about three times the Rayleigh wavelength of said
first reflected wave.
16. The touch sensor according to claim 1, wherein said substrate has a
thickness of about four times the Rayleigh wavelength of said first
reflected wave.
17. The touch sensor according to claim 1, wherein said substrate is glass
having a thickness of about between about 0.085" and 0.125".
18. The touch sensor according to claim 1, wherein said substrate is formed
of plastic.
19. The touch sensor according to claim 1, wherein said substrate is formed
of glass.
20. The touch sensor according to claim 19, wherein said substrate is
formed of soda-lime glass.
21. The touch sensor according to claim 19, wherein said substrate is
formed of borosilicate glass.
22. The touch sensor according to claim 19, wherein said substrate is
formed of frosted glass.
23. The touch sensor according to claim 1, wherein said substrate is formed
of a longitudinal laminate of a lower shear-wave-velocity material on top
of a higher-shear-wave-velocity material, and wherein said first reflected
wave is a Love wave.
24. The touch sensor according to claim 23, wherein said substrate
comprises a borosilicate glass laminated to a soda-lime glass.
25. The touch sensor according to claim 23, wherein said first reflected
wave is a Love wave.
26. The touch sensor according to claim 23, wherein said lower
shear-wave-velocity material is sufficiently thin to support only the n=0
Love mode.
27. The touch sensor according to claim 1, wherein said transducer
comprises a PZT piezoelectric transducer.
28. The touch sensor according to claim 27, wherein said PZT piezoelectric
transducer produces compression waves and is mounted on a plastic wedge in
contact with said surface of said substrate, for inducing propagation of
waves having a longitudinal component in said substrate.
29. The touch sensor according to claim 1, wherein said substrate is
curved.
30. The touch sensor according to claim 1, further comprising:
a receiving transducer for receiving an acoustic wave; and
a receiving reflecting array, for reflecting a wave from said first
reflecting array to said receiving transducer.
31. The touch sensor according to claim 1, wherein said reflecting array
comprises an acoustic diffraction grating.
32. The touch sensor according to claim 31, wherein said acoustic
diffraction grating has elements of varying height.
33. The touch sensor according to claim 31, wherein said acoustic
diffraction grating has elements of varying spacing.
34. The touch sensor according to claim 31, wherein said acoustic
diffraction grating has elements of varying orientation.
35. The touch sensor according to claim 1, wherein said perturbation in the
surface energy of said first reflected wave is detected as a perturbed
wave having a differing volumetric energy distribution along said vertical
axis than said first reflected wave.
36. The touch sensor according to claim 35, wherein said perturbed wave is
selectively filtered from said first reflected wave.
37. The touch sensor according to claim 31, wherein said acoustic
diffraction grating comprises elements which have a shear-type phase
velocity which varies from a shear-type phase velocity of an adjacent
area.
38. The touch sensor according to claim 1, wherein said wave having a
longitudinal component is a Stoneley wave.
39. A touch sensor comprising:
a substrate capable of propagating a horizontally polarized shear-type wave
having an order greater than zero, said substrate having at least one
touch surface, a touch on said substrate causing a perturbation of said
horizontally polarized shear-type wave;
a transducer producing a vertically polarized transverse wave having a
longitudinal component in a wave propagating area;
means for converting said vertically polarized transverse wave having a
longitudinal component propagating in said wave propagating area into said
horizontally polarized shear-type wave having an order greater than zero
propagating in said substrate; and
means for sensing a touch-induced perturbation of said horizontally
polarized shear-type wave.
40. A touch position sensor comprising:
a substrate having at least one touch surface and being capable of
propagating an acoustic wave having a horizontal shear-type component
substantially parallel to said surface, having a non-uniform volumetric
energy density along a vertical axis normal to said surface and having
energy at said surface;
means for reflecting portions of a wave having a longitudinal component as
at least an acoustic wave having a horizontal shear-type component
substantially parallel to said surface, having a non-uniform volumetric
energy density along a vertical axis normal to said surface and having
energy at said surface, having an axis, along paths having differing
displacements along said axis, said reflecting means being disposed on
said substrate;
means for generating a wave having longitudinal component, propagating in
said substrate in a direction along said axis of said reflecting means, a
touch on said substrate touch surface perturbing said acoustic wave; and
means for sensing the time of occurrence of a perturbation.
41. The touch sensor according to claim 40, wherein said acoustic wave
having a horizontal shear-type component substantially parallel to said
surface, having a non-uniform volumetric energy density along a vertical
axis normal to said surface and having energy at said surface is a shear
wave having an order greater than zero.
42. The touch position sensor according to claim 40, wherein said substrate
has a thickness greater than about three times the Rayleigh wavelength of
said acoustic wave.
43. The touch position sensor according to claim 40, wherein said substrate
has a thickness greater than about four times the Rayleigh wavelength of
said acoustic wave.
44. The touch position sensor according to claim 40, wherein said substrate
comprises a glass sheet.
45. The touch position sensor according to claim 40, wherein said substrate
comprises a sheet selected from the group consisting of soda-lime glass,
borosilicate glass, crystal glass, a laminate of borosilicate glass and
soda-lime glass, a laminate of plastic and glass, frosted glass, tempered
glass, plastic, metal and ceramic.
46. The touch position sensor according to claim 40, wherein said substrate
is a sheet having a shape selected from the group consisting of a flat
sheet, a cylindrical section, a spherical section, an ellipsoidal section
and a conic section.
47. The touch position sensor according to claim 40, wherein said
generating means comprises a first transducer bonded on a surface in
acoustic communication with said substrate.
48. The touch position sensor according to claim 47, wherein said
generating means comprises a conductive frit for bonding said transducer
to said surface.
49. The touch position sensor according to claim 48, further comprising a
second transducer bonded on a surface in acoustic communication with said
substrate, said second transducer being proximate to said first transducer
wherein said conductive frit for bonding said first transducer is
continuous with conductive frit to bond said second transducer to said
surface.
50. The touch position sensor according to claim 40, further comprising
means for reflecting portions of said perturbed acoustic wave as a
perturbed wave having a longitudinal component propagating along an axis.
51. The touch position sensor according to claim 40, wherein said sensing
means comprises a receiving transducer for receiving information relating
to a perturbation of said acoustic wave.
52. The touch position sensor according to claim 40, wherein said
generating means and said sensing means employ a common transducer.
53. The touch position sensor according to claim 40, wherein said sensing
means selects substantially a single perturbed acoustic wave mode
propagating in said substrate and directs said selected perturbed acoustic
wave mode to a receiving transducer.
54. The touch position sensor according to claim 40, wherein said acoustic
wave propagates at substantially right angles to said wave having a
longitudinal component.
55. The touch position sensor according to claim 54, wherein said acoustic
wave is a horizontally polarized shear-type wave having an order greater
than zero.
56. The touch position sensor according to claim 40, wherein said wave
having a longitudinal component is a quasi-Rayleigh wave.
57. The touch position sensor according to claim 40, wherein said acoustic
wave is a fourth order horizontally polarized shear-type wave.
58. The touch position sensor according to claim 40, wherein said substrate
has a spatial variation in phase propagation velocity of shear wave energy
and said acoustic wave is a Love wave of any order.
59. The touch position sensor according to claim 58, wherein said spatial
variation is along an axis normal to said surface.
60. The touch position sensor according to claim 40, wherein said perturbed
acoustic wave propagates in the same mode as said acoustic wave.
61. The touch position sensor according to claim 40, wherein said perturbed
acoustic wave propagates in a different mode as said acoustic wave.
62. A touch sensor comprising:
a substrate having at least one touch surface and being capable of
propagating an acoustic wave having a horizontal shear-type component
substantially parallel to said surface, having a non-uniform volumetric
energy density along a vertical axis normal to said surface and having
energy at said surface;
first means for reflecting portions of a wave having a longitudinal
component as a first acoustic wave having a horizontal shear-type
component substantially parallel to said surface, having a non-uniform
volumetric energy density along a vertical axis normal to said surface and
having energy at said surface along first paths having differing
displacement along a first axis of said first reflecting means; and
second means for reflecting portions of a wave having a longitudinal
component as a second acoustic wave having a horizontal shear-type
component substantially parallel to said surface, having a non-uniform
volumetric energy density along a vertical axis normal to said surface and
having energy at said surface along first paths having differing
displacement along a second axis of said second reflecting means.
63. The touch sensor according to claim 62, wherein at least on of said
first acoustic wave and said second acoustic wave is a horizontally
polarized shear-type wave having an order greater than zero.
64. The touch sensor according to claim 62, further comprising:
a reflector for reflecting waves having a longitudinal component
propagating between said first axis and said second axis; and
a transducer for transmitting a wave having longitudinal component along
said first axis and for receiving information from said first and second
horizontally polarized shear-type waves.
65. The touch sensor according to claim 62, wherein said first reflecting
means comprises protuberances from a surface of said substrate having a
spacing of an integral multiple of a wavelength of said wave having a
longitudinal component and an angle with respect to said first axis such
that said first acoustic wave propagates at right angles to said first
axis.
66. The touch sensor according to claim 65, wherein said wave having a
longitudinal component is a quasi-Raleigh wave having a frequency of about
5.5 MHz, said first acoustic wave is a fourth order horizontally polarized
shear-type wave, and said protuberances are set at an angle of 52.degree.
from said first axis.
67. The touch sensor according to claim 62, further comprising a first
transducer for propagating a wave having a longitudinal component along
said first axis and a second transducer for propagating a wave having a
longitudinal component along said second axis.
68. The touch sensor according to claim 67, wherein said first transducer
and said second transducer produce waves having the same order.
69. The touch sensor according to claim 67, wherein said first transducer
is responsive to a wave propagating along said first axis and said second
transducer is responsive to a wave propagating along said second axis.
70. The touch sensor according to claim 69, further comprising means for
directing energy from said first acoustic wave to said first transducer
and means for directing energy from said second acoustic wave to said
second transducer.
71. The touch sensor according to claim 62, wherein:
said first reflecting means comprises a first reflective array disposed on
said substrate and a second reflective array disposed on said substrate
parallel to and spaced from said first reflective array, said first
reflective array reflecting said first acoustic wave from said first axis
toward said second reflective array; and
said second reflecting means comprises a third reflective array disposed on
said substrate and a fourth reflective array disposed on said substrate
parallel to and spaced from said third reflective array, said third
reflective array reflecting said second acoustic wave from said second
axis toward said second reflective array.
72. The touch sensor according to claim 62, wherein said first reflecting
means comprises:
a first reflective edge of said substrate;
a second reflective edge of said substrate, said second reflective edge
being disposed parallel to said first reflective edge and spaced
therefrom;
a first array of reflective elements positioned adjacent said first
reflective edge; and
a second array of reflective elements positioned adjacent said second
reflective edge,
a wave having a longitudinal component propagating along said first axis
intersecting said first array of reflective elements and being reflected
by said first array of reflecting elements as said first acoustic wave
toward said first reflecting edge, said first reflecting edge reflecting
said first acoustic wave toward said second reflecting edge, said second
reflecting edge reflecting said first acoustic wave to said second array
of reflecting elements, and said second array of reflecting elements
reflecting said first acoustic wave as a wave having a longitudinal
component along said second axis.
73. The touch sensor according to claim 72, further comprising a
transmitting acoustic transducer aligned with said first axis and a
receiving acoustic transducer aligned with said second axis.
74. The touch sensor according to claim 72, wherein said wave having a
longitudinal component also has a vertically polarized transverse
component, further comprising members for absorbing waves having vertical
components between said first reflective array and said first reflective
edge.
75. The touch sensor according to claim 74, further comprising members for
absorbing waves having vertical components between said second reflective
array and said second reflective edge.
76. The touch sensor according to claim 69, further comprising an analog to
digital converter and a digital signal processor, said analog to digital
converter digitizing a signal from said first transducer and said digital
signal processor receiving said digitized signal and processing said
signal to filter signal components to selectively extract information
relating to said first acoustic wave.
77. The touch sensor according to claim 67, further comprising means for
generating a drive signal and means for controlling the application of
said drive signal to said first and second transducers during respective
first and second non-overlapping time periods, wherein said first
transducer produces a wave having a longitudinal component in said
substrate during said first time period and said second transducer
produces a wave having a longitudinal component in said substrate during
said second time period.
78. The touch sensor according to claim 77, wherein said first and second
transducers are responsive to acoustic waves, further comprising a
receiving circuit for receiving signals from said first and second
transducers, and a circuit for blocking the direct effect of a drive
signal from said drive signal generating means from said receiving
circuit.
79. The touch sensor according to claim 63, further comprising a first
reflective edge of said substrate opposite said first reflecting means and
a second reflective edge of said substrate opposite said second reflecting
means, said first reflective edge reflecting said first acoustic wave
along its incident path to said first reflecting means and said second
reflecting edge reflecting said second acoustic wave along its incident
path to said second reflecting means.
80. The touch sensor according to claim 63, wherein said substrate has a
thickness greater than about three times the Rayleigh wavelength for the
substrate material.
81. The touch sensor according to claim 63, wherein said substrate has a
thickness greater than about four times the Rayleigh wavelength for the
substrate material.
82. The touch sensor according to claim 63, wherein said substrate is
formed of one or more materials selected from the group consisting of
glass, soda-lime glass, borosilicate glass, leaded crystal glass, silver
crystal glass, soda-lime borosilicate glass laminate, tempered glass,
frosted glass, plastic, glass plastic laminate, glass-organic polymer
laminate, glass-silicone polymer laminate, metal, ceramic, quartz and
ion-beam treated transparent sheets.
83. The touch sensor according to claim 63, wherein said substrate has a
shape selected from the group consisting of a flat sheet, a curved sheet,
a spheric section, an ellipsoidal section, a cylindrical section, a conic
section and an aspheric section.
84. The touch sensor according to claim 63, further comprising a transducer
mounted on said substrate via a plastic wedge.
85. The touch sensor according to claim 63, further comprising a transducer
having a plurality of interdigital electrodes.
86. The touch sensor according to claim 85, wherein said transducer is
selectively responsive to an acoustic wave mode propagating in said
substrate.
87. The touch sensor according to claim 63, further comprising a transducer
mounted to said substrate on a surface contiguous with a touch sensitive
surface of said substrate.
88. The touch sensor according to claim 63, further comprising a first
transducer and a second transducer mounted on said substrate via a
conductive frit, said second transducer being proximate to said first
transducer and wherein said conductive frit for bonding said first
transducer is continuous with said conductive frit for mounting said
second transducer.
89. The touch sensor according to claim 63, further comprising a vertically
polarized transverse wave suppressor for attenuating a vertically
polarized transverse wave component of said wave having a longitudinal
component.
90. The touch sensor according to claim 89, wherein said first and second
reflecting means each include an array of reflective elements and are each
associated with a vertically polarized transverse wave component
suppressor disposed on a surface of said substrate adjacent to each
respective array of reflective elements.
91. The touch sensor according to claim 90, wherein said vertically
polarized transverse wave component suppressor is disposed on a top
surface and a bottom surface of said substrate.
92. The touch sensor according to claim 63, wherein at least one of said
first acoustic wave and said second acoustic wave is selected from the
group consisting of a third order shear-type wave and a fourth order
shear-type wave.
93. The touch sensor according to claim 92, further comprising a bevelled
edge of said substrate.
94. The touch sensor according to claim 63, further comprising a first
bevelled edge of said substrate associated with said first reflecting
means and a second bevelled edge associated with said second reflecting
means, said bevelled edges having selective reflection characteristics for
acoustic waves having differing volumetric energy density along said
vertical axis.
95. An object proximity sensor comprising:
a substrate having first and second generally parallel edges, and a top
touch surface and being capable of propagating an acoustic wave having a
horizontal shear-type component substantially parallel to said surface,
having a non-uniform volumetric energy density along a vertical axis
normal to said surface and having energy at said surface;
a first transmitting transducer coupled to a surface of said substrate and
responsive to a drive signal for imparting a wave having a longitudinal
wave component into said substrate, said wave propagating along a first
axis parallel to said first edge;
a first array of reflective elements disposed along said first axis and
adjacent to said first edge, said reflective elements being positioned to
reflect portions of said wave having a longitudinal wave component along
first, substantially parallel paths as an acoustic wave having a
horizontal shear-type component substantially parallel to said surface,
having a non-uniform volumetric energy density along a vertical axis
normal to said surface and having energy at said surface, a touch on said
substrate top touch surface forming a perturbation in said acoustic wave
propagating along a first path intersecting the position of the touch; and
a drive signal generator connected to said first transmitting transducer.
96. The object proximity sensor according to claim 95, further comprising
means for generating a signal representative of a perturbed acoustic wave
propagating in said substrate and means responsive to said representative
signal for determining a proximity of an object to said substrate.
97. The object proximity sensor according to claim 95, further comprising a
second array of reflective elements disposed along a second axis parallel
to, and spaced from, said first axis, said second array of reflective
elements being spaced to selectively reflect a portion of said acoustic
wave propagating along said first, substantially parallel paths as a wave
having a longitudinal wave component.
98. The object proximity sensor according to claim 96, further comprising:
means for storing a time at which said first transmitting transducer
imparts a wave into said substrate;
means for storing temporal characteristics of said perturbed acoustic wave;
and
means for calculating a position of an object in proximity to said
substrate based on said stored time and said stored temporal
characteristics.
99. The object proximity sensor according to claim 98, further comprising a
sensor system for receiving said perturbed acoustic wave and means for
determining a position of an object in proximity to said substrate along
an axis having a component which is orthogonal to an axis of said first,
substantially parallel paths based on said received perturbed acoustic
wave.
100. The object proximity sensor according to claim 99, further comprising
means for outputting information relating to a position of said object in
proximity to said substrate.
101. The object proximity sensor according to claim 95, further comprising:
third and fourth edges of said substrate;
a second array of reflective elements disposed along a second axis parallel
to and spaced from said first axis, said reflective elements of said
second array being spaced to selectively reflect a portion of said
incident acoustic waves as a wave having a longitudinal wave component
propagating along said first, substantially parallel paths along a second
axis;
a first receiving transducer, spaced from said first transmitting
transducer and being responsive to a received wave from said second array
of reflecting elements having a longitudinal wave component, and
generating a signal representative thereof;
a second transmitting transducer coupled to a surface of said substrate and
responsive to a drive signal for imparting a wave having a longitudinal
wave component into said substrate, said wave propagating along a third
axis parallel to said third edge;
a third array of reflective elements disposed along said third axis and
adjacent to said third edge, said reflective elements of said third array
being positioned to reflect portions of said wave having a longitudinal
wave component along second, substantially parallel paths as an acoustic
wave having a horizontal shear-type component substantially parallel to
said surface, having a non-uniform volumetric energy density along a
vertical axis normal to said surface and having energy at said surface, a
touch on said substrate top touch surface forming a perturbation in said
acoustic wave propagating along a second path intersecting the position of
the touch; and
a fourth array of reflective elements disposed along a fourth axis parallel
to and spaced from said third axis, said reflective elements of said
fourth array being spaced to selectively reflect a portion of said
incident shear-type waves as a wave having a longitudinal wave component
propagating along said second, substantially parallel paths along a fourth
axis;
a second receiving transducer spaced from said second transmitting
transducer, being responsive to a wave having a longitudinal component
received from said fourth array of reflecting elements, and generating a
signal representative thereof.
102. The object proximity sensor according to claim 101, wherein each of
said transducers is mounted on a plastic wedge.
103. The object proximity sensor according to claim 95, wherein said wave
having a longitudinal wave component also has a vertical wave component,
said sensor further comprising means positioned adjacent to said first
reflective array for attenuating said vertical wave component.
104. The object proximity sensor according to claim 103, wherein said
attenuating means comprise strips of acoustic wave absorbing material
disposed adjacent to said first array of reflective elements.
105. The object proximity sensor according to claim 103, wherein said
attenuating means is disposed between said first array of reflecting
elements and said first side.
106. The object proximity sensor according to claim 95, wherein said
substrate has a thickness which is greater than about three Rayleigh
wavelengths for the substrate material.
107. The object proximity sensor according to claim 95, wherein said
substrate has a thickness which is about four Rayleigh wavelengths for the
substrate material.
108. The object proximity sensor according to claim 95, wherein said
substrate comprises a plate of soda-lime glass of 2 mm thickness or more
laminated to a plate of borosilicate glass of 3 mm thickness or less, said
first transmitting transducer being mounted on said borosilicate glass.
109. The object proximity sensor according to claim 95, wherein said
substrate comprises a laminate of a first material having a first
shear-type wave phase velocity and a second material having a second
shear-type wave phase velocity, said phase velocity of said first material
being different from said phase velocity of said second material, said
laminate being formed in a manner that efficiently couples shear-type
waves between said first material and said second material.
110. The object proximity sensor according to claim 108, wherein said sheet
of soda-lime glass is greater than about 2 mm thick and said sheet of
borosilicate glass is less than about 3 mm thick.
111. The object proximity sensor according to claim 95, wherein said
substrate is transparent and is adapted for transmission of an image from
a display device.
112. The object proximity sensor according to claim 95, wherein said
elements of said first array of reflective elements are disposed at an
angle greater than about 45.degree. from said first axis.
113. The object proximity sensor according to claim 95, wherein said
elements of said first array of reflective elements are disposed at an
angle of about 52.degree. from said first axis.
114. The object proximity sensor according to claim 95, wherein said first
acoustic wave is a horizontally polarized shear-type wave having order
greater than zero.
115. A method of detecting an object, comprising:
providing a substrate having at least one touch surface and being capable
of propagating an acoustic wave having a horizontal shear-type energy
component substantially parallel to said surface, having a nonuniform
volumetric energy density along a vertical axis normal to said surface and
having energy at said surface;
inducing a first acoustic wave having a longitudinal component along a
first axis in the substrate, the first axis being parallel to said
surface;
reflecting, as a second acoustic wave, portions of the energy of the first
acoustic wave, the second acoustic wave having a horizontal shear-type
energy component substantially parallel to the surface, having a
nonuniform volumetric energy density along a vertical axis normal to the
surface, and having energy at the surface, the second acoustic wave being
directed along a second axis in the substrate, different than the first
axis, and being parallel to said surface;
perturbing said second acoustic wave by placing an object in proximity to
said surface of the substrate; and
detecting the perturbed second acoustic wave.
116. The method according to claim 115, wherein:
said perturbing step further comprises redistributing the wave energy of
the second acoustic wave among available propagation modes; and
said detecting step further comprises detecting wave energy in wave
propagation modes not present in said second acoustic wave.
117. The method according to claim 115, further comprising the step of:
reflecting the perturbed wave as a wave having a longitudinal component;
wherein said detecting step comprises detecting acoustic wave energy having
a longitudinal component.
118. The method according to claim 115, wherein the first reflected wave is
a fourth order horizontally polarized shear-type wave.
119. The method according to claims 115, wherein the induced first acoustic
wave is a quasi-Rayleigh wave.
120. The method according to claims 115, wherein the substrate has a
vertical variation in shear-type wave phase velocity and the first
reflected wave is a Love wave.
121. The method according to claim 115, wherein a said detecting step
comprises the substep of receiving the perturbed second acoustic wave with
an acoustic-electric transducer, digitizing an electrical signal from the
transducer, and digitally processing the digitized signal to compensate
for alternate return paths of wave energy received by the transducer.
122. The method according to claim 121, wherein said digitally processing
step is adaptive to changing environmental conditions.
123. The method according to claim 115, wherein | | |
