(12) United States Patent ao) Patent No.: us 6,590,569 Bi
Toda (45) Date of Patent: Jul. 8,2003
(54) ULTRASONIC TOUCH-POSITION SENSING DEVICE
(76) Inventor: Kohji Toda, 1-49-18 Futaba, Yokosuka 239-0814 (JP)
( * ) Notice: Subject to any disclaimer, the term of this patent is extended or adjusted under 35 U.S.C. 154(b) by 365 days.
(21) Appl. No.: 09/747,413
(22) Filed: Dec. 19, 2000
(51) Int. C I. G09G 5/00
(52) U.S. CI 345/173; 345/176; 345/177;
178/18.01; 178/18.03; 178/18.04
(58) Field of Search 345/173-174,
345/176-177; 178/18.01-18.04
(56) References Cited
U.S. PATENT DOCUMENTS
5,986,224 A * 11/1999 Kent 178/18.04
5,994,817 A * 11/1999 Toda 310/313 R
* cited by examiner
Primary Examiner—Bipin Shalwala
Assistant Examiner—Leonid Shapiro
(57) ABSTRACT
An ultrasonic touch-position sensing device comprises a nonpiezoelectric plate, first- and second transducer-units, and a signal analyzer. When a first input electric signal is applied to two neighbors of the input interdigital electrodes Txi, a first SAW is excited in the first piezoelectric substrate, respectively, and is transmitted to the second piezoelectric substrate along the upper end surface of the nonpiezoelectric plate. The first SAW is transduced to a first output electric signal, respectively, at the output interdigital electrodes Rxaj and Rxbj. If touching a position between one of the input interdigital electrodes Txi and one of the output interdigital electrodes Rxaj on the upper end surface of the nonpiezoelectric plate, a first delayed electric signal appears at one of the uniting terminals Uxj twice without stopping. The touch position is sensed at the signal analyzer by clarifying which of the input interdigital electrodes Txi receives the first input electric signal twice without stopping when the first delayed electric signal appears at one of the uniting terminals Uxj twice without stopping.
9 Claims, 7 Drawing Sheets
