Surface acoustic wave position-sensing device
First Claim
1. A surface acoustic wave position-sensing device comprising:
- a piezoelectric substrate having an upper- and a lower end surfaces running perpendicular to the thickness direction thereof;
a nonpiezoelectric plate having an upper- and a lower end surfaces running perpendicular to the direction of the thickness d thereof;
at least two surface acoustic wave transducing units X and Y, each thereof consisting ofN interdigital transducers Ti (i=1, 2, ...... , N) formed on said upper end surface of said piezoelectric substrate, the thickness of said piezoelectric substrate being larger than approximately three times an interdigital periodicity p of said interdigital transducer Ti, said thickness of d of said nonpiezoelectric plate being smaller than said interdigital periodicity p,an interdigital transducer R formed on said upper end surface of said piezoelectric substrate and having an interdigital periodicity equal to said interdigital periodicity p, said lower end surface of said nonpiezoelectric plate being mounted on said upper end surface of said piezoelectric substrate through said interdigital transducers Ti and R, andN switches Wi (i=1, 2, ...... , N), output terminals thereof being connected with input terminals of said interdigital transducers Ti, respectively; and
a controlling system connected with said surface acoustic wave transducing units X and Y,said interdigital transducer Ti receiving an electric signal ET with a frequency approximately corresponding to said interdigital periodicity p, exciting a surface acoustic wave of the zeroth mode and the higher order modes on an area, in contact with said interdigital transducer Ti, of said upper end surface of said piezoelectric substrate, and transmitting said surface acoustic wave having the wavelength approximately equal to said interdigital periodicity p to an area, in contact with said interdigital transducer R, of said upper end surface of said piezoelectric substrate, through said nonpiezoelectric plate, the phase velocity of said surface acoustic wave of said zeroth mode being approximately equal to the phase velocity of the Rayleigh wave traveling on said piezoelectric substrate alone under the electrically shorted condition, the phase velocity of said surface acoustic wave of said higher order modes being approximately equal to the phase velocity of the Rayleigh wave traveling on said piezoelectric substrate alone under the electrically opened condition,said interdigital transducer R transducing said surface acoustic wave transmitted to said area, in contact with said interdigital transducer R, of said upper end surface of said piezoelectric substrate, 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 surface acoustic wave traveling on said nonpiezoelectric plate alone is lower than that traveling on said piezoelectric substrate alone,said controlling system turning on and off said 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 on said upper 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 Wi turned on when said decrease or said disappearance in magnitude of said electric signal ER happens,said surface acoustic wave transducing unit X having N propagation lanes UXi (i=1, 2, ...... , N) of said surface acoustic wave between said interdigital transducers Ti and R, two neighbors of said propagation lanes UXi being closed or partially overlapping each other,said surface acoustic wave transducing unit Y having N propagation lanes UYi (i=1, 2, ...... , N) of said surface acoustic wave between said interdigital transducers Ti and R, two neighbors of said propagation lanes UYi being closed or partially overlapping each other, said propagation lane UX being vertical to said propagation lane UYi.
0 Assignments
0 Petitions
Accused Products
Abstract
A surface acoustic wave position-sensing device comprising a piezoelectric substrate, a nonpiezoelectric plate, at least two surface acoustic wave transducing units X and Y having N propagation lanes UXi (i=1, 2, ...... , N) and UYi (i=1, 2, ...... , N), respectively, and a controlling system connected with the units X and Y. Each unit includes input and output interdigital transducers formed on the upper end surface of the piezoelectric substrate. One end surface of the nonpiezoelectric plate is mounted on the upper end surface of the piezoelectric substrate through the interdigital transducers. When an electric signal ET is applied to the input interdigital transducer, a surface acoustic wave is excited on an area, in contact with the input interdigital transducer, of the upper end surface of the piezoelectric substrate. The surface acoustic wave is transmitted to an area, in contact with the output interdigital transducer, of the upper end surface of the piezoelectric substrate, through the nonpiezoelectric plate, and is transduced to an electric signal ER. If touching a crossing point of the lanes UXi and UYi n the upper end surface of the nonpiezoelectric plate, the surface acoustic 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.
-
Citations
8 Claims
-
1. A surface acoustic wave position-sensing device comprising:
-
a piezoelectric substrate having an upper- and a lower end surfaces running perpendicular to the thickness direction thereof; a nonpiezoelectric plate having an upper- and a lower end surfaces running perpendicular to the direction of the thickness d thereof; at least two surface acoustic wave transducing units X and Y, each thereof consisting of N interdigital transducers Ti (i=1, 2, ...... , N) formed on said upper end surface of said piezoelectric substrate, the thickness of said piezoelectric substrate being larger than approximately three times an interdigital periodicity p of said interdigital transducer Ti, said thickness of d of said nonpiezoelectric plate being smaller than said interdigital periodicity p, an interdigital transducer R formed on said upper end surface of said piezoelectric substrate and having an interdigital periodicity equal to said interdigital periodicity p, said lower end surface of said nonpiezoelectric plate being mounted on said upper end surface of said piezoelectric substrate through said interdigital transducers Ti and R, and N switches Wi (i=1, 2, ...... , N), output terminals thereof being connected with input terminals of said interdigital transducers Ti, respectively; and a controlling system connected with said surface acoustic wave transducing units X and Y, said interdigital transducer Ti receiving an electric signal ET with a frequency approximately corresponding to said interdigital periodicity p, exciting a surface acoustic wave of the zeroth mode and the higher order modes on an area, in contact with said interdigital transducer Ti, of said upper end surface of said piezoelectric substrate, and transmitting said surface acoustic wave having the wavelength approximately equal to said interdigital periodicity p to an area, in contact with said interdigital transducer R, of said upper end surface of said piezoelectric substrate, through said nonpiezoelectric plate, the phase velocity of said surface acoustic wave of said zeroth mode being approximately equal to the phase velocity of the Rayleigh wave traveling on said piezoelectric substrate alone under the electrically shorted condition, the phase velocity of said surface acoustic wave of said higher order modes being approximately equal to the phase velocity of the Rayleigh wave traveling on said piezoelectric substrate alone under the electrically opened condition, said interdigital transducer R transducing said surface acoustic wave transmitted to said area, in contact with said interdigital transducer R, of said upper end surface of said piezoelectric substrate, 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 surface acoustic wave traveling on said nonpiezoelectric plate alone is lower than that traveling on said piezoelectric substrate alone, said controlling system turning on and off said 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 on said upper 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 Wi turned on when said decrease or said disappearance in magnitude of said electric signal ER happens, said surface acoustic wave transducing unit X having N propagation lanes UXi (i=1, 2, ...... , N) of said surface acoustic wave between said interdigital transducers Ti and R, two neighbors of said propagation lanes UXi being closed or partially overlapping each other, said surface acoustic wave transducing unit Y having N propagation lanes UYi (i=1, 2, ...... , N) of said surface acoustic wave between said interdigital transducers Ti and R, two neighbors of said propagation lanes UYi being closed or partially overlapping each other, said propagation lane UX being vertical to said propagation lane UYi. - View Dependent Claims (2, 3, 4)
-
-
5. A surface acoustic wave position-sensing device comprising:
-
a piezoelectric substrate having an upper- and a lower end surfaces running perpendicular to the thickness direction thereof; a nonpiezoelectric plate having an upper- and a lower end surfaces running perpendicular to the direction of the thickness d thereof; at least two surface acoustic wave transducing units X and Y, each thereof consisting of an interdigital transducer T formed on said upper end surface of said piezoelectric substrate, the thickness of said piezoelectric substrate being larger than approximately three times an interdigital periodicity p of said interdigital transducer T, said thickness d of said nonpiezoelectric plate being smaller than said interdigital periodicity p, and N interdigital transducers Ri (i=1, 2, ...... , N) formed on said upper end surface of said piezoelectric substrate and having an interdigital periodicity equal to said interdigital periodicity p, said lower end surface of said nonpiezoelectric plate being mounted on said upper end surface of said piezoelectric substrate through said interdigital transducers T and Ri ; and a controlling system connected with said two surface acoustic wave transducing units X and Y, said interdigital transducer T receiving an electric signal ET with a frequency approximately corresponding to said interdigital periodicity p, exciting a surface acoustic wave of the zeroth mode and the higher order modes on an area, in contact with said interdigital transducer T, of said upper end surface of said piezoelectric substrate, and transmitting said surface acoustic wave having the wavelength approximately equal to said interdigital periodicity p to an area, in contact with said interdigital transducers Ri, of said upper end surface of said piezoelectric substrate, through said nonpiezoelectric plate, the phase velocity of said surface acoustic wave of said zeroth mode being approximately equal to the phase velocity of the Rayleigh wave traveling on said piezoelectric substrate alone under the electrically shorted condition, the phase velocity of said surface acoustic wave of said higher order modes being approximately equal to the phase velocity of the Rayleigh wave traveling on said piezoelectric substrate alone under the electrically opened condition, said interdigital transducers Ri transducing said surface acoustic wave transmitted to said area, in contact with said interdigital transducers Ri, of said upper end surface of said piezoelectric substrate, to electric signals ERi (i=1, 2, ...... , N), said electric signal ERi, having a frequency approximately corresponding to said interdigital periodicity p, said nonpiezoelectric plate being made of a material such that the phase velocity of the surface acoustic wave traveling on said nonpiezoelectric plate alone is lower than that traveling on said piezoelectric substrate alone, said controlling system keeping a check on a magnitude of said electric signals ERi, sensing a touch with a finger or others on said upper end surface of said nonpiezoelectric plate by a decrease or a disappearance in magnitude of said electric signals ERi, picking out at least one of said interdigital transducers Ri corresponding to said decrease or said disappearance in magnitude of said electric signals ERi, said surface acoustic wave transducing unit X having N propagation lanes UXi (i=1, 2, ...... , N) of said surface acoustic wave between said interdigital transducers T and Ri, two neighbors of said propagation lanes UXi being closed or partially overlapping each other, said surface acoustic wave transducing unit Y having N propagation lanes UYi (i=1, 2, ...... , N) of said surface acoustic wave between said interdigital transducers T and Ri, 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 (6, 7, 8)
-
Specification