| 摘要 |
PROBLEM TO BE SOLVED: To reduce a group delay time deviation by bonding a thin film smaller than an electrode near the electrode arranged in the center. SOLUTION: Electrodes 2a, 3a and 4a in equal forms are arranged on the main face of a piezoelectric substrate 1 in parallel to a long side by giving an electrode gap g1. Electrodes 2b, 3b and 4b are arranged by making them face the electrodes 2a, 3a and 4a at a back face. Lead electrodes 5a-7b are installed at the end parts of the piezoelectric substrate 1 from the respective electrodes 2a-4b and lead electrodes 6a and 6b are overlapped in the positions of a distance W2 from end sides parallel to the array directions of the center electrodes 3a and 3b or strip-type metal films 8 with width W1 are formed on opposite sides. When high frequency voltage is applied between the electrodes 2a and 2b, acoustic connection is generated between the electrodes 2a-7b and multiple thickness slip vibrations are executed. A symmetrical primary mode F1, an asymmetrical primary mode F2 and a symmetrical mode F3 are compulsorily excited with three pairs of electrode forms and a filter functions as a band pass filter using the three modes.
|
