Elastic wave position-sensing device
First Claim
1. An elastic wave position-sensing device comprising:
- at least two elastic wave transducing units X and Y, each thereof consisting ofa piezoelectric substrate PT having two end surfaces running perpendicular to the direction of the thickness D thereof, and comprising N piezoelectric parts PTi (i=1, 2, . . . , N),a piezoelectric substrate PR having two end surfaces running perpendicular to the direction of the thickness D thereof,N interdigital transducers ITi (i=1, 2, . . . , N), each thereof being formed on one end surface of each of said piezoelectric parts PTi, said thickness D of said piezoelectric substrate PT being approximately equal to or smaller than an interdigital periodicity p of said interdigital transducer ITi,an interdigital transducer IR formed on one end surface of said piezoelectric substrate PR and having an interdigital periodicity equal to said interdigital periodicity p, said thickness D of said piezoelectric substrate PR being approximately equal to or smaller than said interdigital periodicity p, andN switches Ci (i=1, 2, . . . , N), an output terminal of each thereof being connected with an input terminal of each of said interdigital transducers ITi ;
a nonpiezoelectric plate having two end surfaces, the thickness of said nonpiezoelectric plate being equal to or smaller than said thickness D of said piezoelectric substrates PT and PR, said piezoelectric substrates PT and PR being mounted on one or the other end surface of said nonpiezoelectric plate, said nonpiezoelectric plate comprising N nonpiezoelectric parts Ti (i=1, 2, . . . , N) adjacent to said piezoelectric parts PTi, a nonpiezoelectric part R adjacent to said piezoelectric substrate PR, and the remaining nonpiezoelectric part;
a display panel, mounted on said one end surface of said nonpiezoelectric plate; and
a controlling system connected with said elastic wave transducing units X and Y, and said display panel,said piezoelectric substrates PT and PR, and said nonpiezoelectric plate formingN bilayer zones LTi (i=1, 2, . . . , N) consisting of said piezoelectric parts PTi and said nonpiezoelectric parts Ti,a bilayer zone LR consisting of said piezoelectric substrate PR and said nonpiezoelectric part R, anda monolayer zone between said bilayer zones LTi and said bilayer zone LR, and consisting of said remaining nonpiezoelectric part,said interdigital transducer ITi receiving an electric signal ET with a frequency approximately corresponding to said interdigital periodicity p, exciting an elastic wave of the So mode and the higher order modes in said bilayer zone LTi, and transmitting said elastic wave, having the wavelength approximately equal to said interdigital periodicity p, to said bilayer zone LR through said monolayer zone, the phase velocity of said elastic wave being approximately equal to the phase velocity Vfd=0, of the So mode elastic wave, corresponding to a condition that the product FD of the frequency F of said elastic wave and said thickness D of said piezoelectric substrate PT is zero,said interdigital transducer IR transducing said elastic wave in said bilayer zone LR to an electric signal ER with a frequency approximately corresponding to said interdigital periodicity p,said nonpiezoelectric plate being made of a material such that the phase velocity of the elastic wave in said nonpiezoelectric plate alone is approximately equal to that in said piezoelectric substrates PT and PR alone,said controlling system turning on and off said switches Ci with a fixed period in turn, keeping a check on a magnitude of said electric signal ER, sensing a touch with a finger or others under a fixed or more pressure on the other end surface of said nonpiezoelectric plate by a decrease or a disappearance in magnitude of said electric signal ER, picking out one of said switches Ci turned on when said decrease or said disappearance in magnitude of said electric signal ER happens, specifying a touch-position corresponding with the picked out switch Ci, and producing an image corresponding to said touch-position on said display panel,said elastic wave transducing unit X having N propagation lanes UXi (i=1, 2, . . . , N) of the elastic wave in said monolayer zone between said bilayer zones LTi and LR, two neighbors of said propagation lanes UXi being closed or partially overlapping each other,said elastic wave transducing unit Y having N propagation lanes UYi (i=1, 2, . . . , N) of the elastic wave in said monolayer zone between said bilayer zones LTi and LR, two neighbors of said propagation lanes UYi being closed or partially overlapping each other, said propagation lane UXi being vertical to said propagation lane UYi.
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Abstract
An elastic wave position-sensing device comprising at least two elastic wave transducing units X and Y having N propagation lanes UXi (i=1, 2, . . . , N) and UYi (i=1, 2, . . . , N), respectively, a nonpiezoelectric plate, a display panel mounted on one end surface of the nonpiezoelectric plate, and a controlling system connected with the units X and Y. Each unit includes a piezoelectric substrate PT, a piezoelectric substrate PR, at least an input interdigital transducer formed on one end surface of the piezoelectric substrate PT, and at least an output interdigital transducer formed on one end surface of the piezoelectric substrate PR. Each piezoelectric substrates mounted on one or the other end surface of the nonpiezoelectric plate and the nonpiezoelectric plate form N bilayer zones LTi (i=1, 2, . . . , N), a bilayer zone LR, and a monolayer zone between the bilayer zones LTi and the bilayer zone LR. When an electric signal ET is applied to the input interdigital transducer, an elastic wave is excited in the bilayer zone LTi. The elastic wave is transmitted to the bilayer zone LR through the monolayer zone, and is transduced to an electric signal ER. If touching a crossing point of the lanes UXi and UYi on the other end surface of the nonpiezoelectric plate, the elastic wave is intercepted at the crossing point. Therefore, the magnitude of the electric signal ER corresponding to the crossing point decrease or disappearance. Thus, it is possible to specify the crossing point.
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Citations
13 Claims
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1. An elastic wave position-sensing device comprising:
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at least two elastic wave transducing units X and Y, each thereof consisting of a piezoelectric substrate PT having two end surfaces running perpendicular to the direction of the thickness D thereof, and comprising N piezoelectric parts PTi (i=1, 2, . . . , N), a piezoelectric substrate PR having two end surfaces running perpendicular to the direction of the thickness D thereof, N interdigital transducers ITi (i=1, 2, . . . , N), each thereof being formed on one end surface of each of said piezoelectric parts PTi, said thickness D of said piezoelectric substrate PT being approximately equal to or smaller than an interdigital periodicity p of said interdigital transducer ITi, an interdigital transducer IR formed on one end surface of said piezoelectric substrate PR and having an interdigital periodicity equal to said interdigital periodicity p, said thickness D of said piezoelectric substrate PR being approximately equal to or smaller than said interdigital periodicity p, and N switches Ci (i=1, 2, . . . , N), an output terminal of each thereof being connected with an input terminal of each of said interdigital transducers ITi ; a nonpiezoelectric plate having two end surfaces, the thickness of said nonpiezoelectric plate being equal to or smaller than said thickness D of said piezoelectric substrates PT and PR, said piezoelectric substrates PT and PR being mounted on one or the other end surface of said nonpiezoelectric plate, said nonpiezoelectric plate comprising N nonpiezoelectric parts Ti (i=1, 2, . . . , N) adjacent to said piezoelectric parts PTi, a nonpiezoelectric part R adjacent to said piezoelectric substrate PR, and the remaining nonpiezoelectric part; a display panel, mounted on said one end surface of said nonpiezoelectric plate; and a controlling system connected with said elastic wave transducing units X and Y, and said display panel, said piezoelectric substrates PT and PR, and said nonpiezoelectric plate forming N bilayer zones LTi (i=1, 2, . . . , N) consisting of said piezoelectric parts PTi and said nonpiezoelectric parts Ti, a bilayer zone LR consisting of said piezoelectric substrate PR and said nonpiezoelectric part R, and a monolayer zone between said bilayer zones LTi and said bilayer zone LR, and consisting of said remaining nonpiezoelectric part, said interdigital transducer ITi receiving an electric signal ET with a frequency approximately corresponding to said interdigital periodicity p, exciting an elastic wave of the So mode and the higher order modes in said bilayer zone LTi, and transmitting said elastic wave, having the wavelength approximately equal to said interdigital periodicity p, to said bilayer zone LR through said monolayer zone, the phase velocity of said elastic wave being approximately equal to the phase velocity Vfd=0, of the So mode elastic wave, corresponding to a condition that the product FD of the frequency F of said elastic wave and said thickness D of said piezoelectric substrate PT is zero, said interdigital transducer IR transducing said elastic wave in said bilayer zone LR to an electric signal ER with a frequency approximately corresponding to said interdigital periodicity p, said nonpiezoelectric plate being made of a material such that the phase velocity of the elastic wave in said nonpiezoelectric plate alone is approximately equal to that in said piezoelectric substrates PT and PR alone, said controlling system turning on and off said switches Ci with a fixed period in turn, keeping a check on a magnitude of said electric signal ER, sensing a touch with a finger or others under a fixed or more pressure on the other end surface of said nonpiezoelectric plate by a decrease or a disappearance in magnitude of said electric signal ER, picking out one of said switches Ci turned on when said decrease or said disappearance in magnitude of said electric signal ER happens, specifying a touch-position corresponding with the picked out switch Ci, and producing an image corresponding to said touch-position on said display panel, said elastic wave transducing unit X having N propagation lanes UXi (i=1, 2, . . . , N) of the elastic wave in said monolayer zone between said bilayer zones LTi and LR, two neighbors of said propagation lanes UXi being closed or partially overlapping each other, said elastic wave transducing unit Y having N propagation lanes UYi (i=1, 2, . . . , N) of the elastic wave in said monolayer zone between said bilayer zones LTi and LR, two neighbors of said propagation lanes UYi being closed or partially overlapping each other, said propagation lane UXi being vertical to said propagation lane UYi. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An elastic wave position-sensing device comprising:
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at least two elastic wave transducing units X and Y, each thereof consisting of a piezoelectric substrate PT having two end surfaces running perpendicular to the direction of the thickness D thereof, and comprising N piezoelectric parts PTi (i=1, 2, . . . , N), a piezoelectric substrate PR having two end surfaces running perpendicular to the direction of the thickness D thereof, N interdigital transducers Ti (i=1, 2, . . . , N), each thereof being formed on one end surface of each of said piezoelectric parts PTi, each of said interdigital transducers Ti consisting of two electrodes Ti-1 and Ti-2 and having two kinds of distances between one electrode finger of said electrode Ti-1 and two neighboring electrode fingers of said electrode Ti-2, said thickness D of said piezoelectric substrate PT being approximately equal to or smaller than an interdigital periodicity p of said interdigital transducer Ti, an interdigital transducer R formed on one end surface of said piezoelectric substrate PR, consisting of two electrodes R-1 and R-2, and having two kinds of distances between one electrode finger of said electrode R-1 and two neighboring electrode fingers of said electrode R-2, said thickness D of said piezoelectric substrate PR being approximately equal to or smaller than an interdigital periodicity p of said interdigital transducer R, N earth electrodes GTi (i=1, 2, . . . , N), each thereof being formed on the other end surface of each of said piezoelectric parts PTi, an earth electrode GR formed on the other end surface of said piezoelectric substrate PR, a phase shifter ST including at least a coil L1, a phase shifter SR including at least a coil L2, and N pairs of switches Wi (i=1, 2, . . . , N), each pair of switches Wi consisting of two switches Wi-1 and Wi-2, and output terminals of said switches Wi-1 and Wi-2 being connected with input terminals of said electrodes Ti-1 and Ti-2, respectively; a nonpiezoelectric plate having two end surfaces, the thickness of said nonpiezoelectric plate being equal to or smaller than said thickness D of said piezoelectric substrates PT and PR, said piezoelectric substrates PT and PR being mounted on one or the other end surface of said nonpiezoelectric plate through said earth electrodes GTi and GR, respectively, said nonpiezoelectric plate comprising N nonpiezoelectric parts Ti (i=1, 2, . . . , N) adjacent to said piezoelectric parts PTi, a nonpiezoelectric part R adjacent to said piezoelectric substrate PR, and the remaining nonpiezoelectric part; a display panel, mounted on said one end surface of said nonpiezoelectric plate; and a controlling system connected with said two elastic wave transducing units X and Y, and said display panel, said piezoelectric substrates PT and PR, and said nonpiezoelectric plate forming N bilayer zones LTi (i=1, 2, . . . , N) consisting of said piezoelectric parts PTi and said nonpiezoelectric parts Ti, a bilayer zone LR consisting of said piezoelectric substrate PR and said nonpiezoelectric part R, and a monolayer zone between said bilayer zones LTi and said bilayer zone LR, and consisting of said remaining nonpiezoelectric part, said interdigital transducer Ti and said earth electrode GTi receiving an electric signal ET1 between said electrode Ti-1 and said earth electrode GTi, and an electric signal ET2 between said electrode Ti-2 and said earth electrode GTi via said phase shifter ST, exciting an elastic wave of the So mode and the higher order modes in said bilayer zone LTi, and transmitting said elastic wave, having the wavelength approximately equal to said interdigital periodicity p of said interdigital transducer Ti, to said bilayer zone LR through said monolayer zone, each of said electric signals ET1 and ET2 having a frequency approximately corresponding to said interdigital periodicity p of said interdigital transducer Ti, the phase difference between said electric signals ET1 and ET2 being 2π
y, the phase velocity of said elastic wave being approximately equal to the phase velocity Vfd=0, of the So mode elastic wave, corresponding to a condition that the product FD of the frequency F of said elastic wave and said thickness D of said piezoelectric substrate PT is zero,said interdigital transducer R and said earth electrode GR transducing said elastic wave in said bilayer zone LR, with wavelength approximately equal to said interdigital periodicity p of said interdigital transducer R, to an electric signal ER1 between said electrode R-1 and said earth electrode GR, and an electric signal ER2 between said electrode R-2 and said earth electrode GR, each of said electric signals ER1 and ER2 having a frequency approximately corresponding to said interdigital periodicity p of said interdigital transducer R, the phase difference between said electric signals ER1 and ER2 being 2π
y,said phase shifter SR combining said electric signals ER1 and ER2, and delivering a combined electric signal ER, said nonpiezoelectric plate being made of a material such that the phase velocity of the elastic wave in said nonpiezoelectric plate alone is approximately equal to that in said piezoelectric substrates PT and PR alone, said controlling system turning on and off said pairs of switches Wi with a fixed period in turn, keeping a check on a magnitude of said electric signal ER, sensing a touch with a finger or others under a fixed or more pressure on the other end surface of said nonpiezoelectric plate by a decrease or a disappearance in magnitude of said electric signal ER, picking out said pair of switches Wi turned on when said decrease or said disappearance in magnitude of said electric signal ER happens, specifying a touch-position corresponding with the picked out pair of switches Wi, and producing an image corresponding to said touch-position on said display panel, said elastic wave transducing unit X having N propagation lanes UXi (i=1, 2, . . . , N) of the elastic wave in said monolayer zone between said bilayer zones LTi and LR in said elastic wave transducing unit X, two neighbors of said propagation lanes UXi being closed or partially overlapping each other, said elastic wave transducing unit Y having N propagation lanes UYi (i=1, 2, . . . , N) of the elastic wave in said monolayer zone between said bilayer zones LTi and LR in said elastic wave transducing unit Y, two neighbors of said propagation lanes UYi being closed or partially overlapping each other, said propagation lane UXi being vertical to said propagation lane UYi. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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Specification