| 摘要 |
PURPOSE:To change a frequency pass band by dividing a driving thin film electrode provided on both major planes of a piezoelectric material processed in the form of strip into two and connecting the divided parts with a photoconductive film. CONSTITUTION:Two pairs of driving thin film electrodes 3 are provided on both major planes of a vibrator element plate 1 made by processing a piezoelectric material in the form of strip so as to constitute two resonators on one vibrator element plate 1. Each drive thin electrode 3 is divided at a right angle in the lengthwise direction of the strip and the divided driving thin film electrodes 3a, 3b are connected by the photoconductive film 3c having a resistance characteristic of <=1kOMEGA/mm.<2> at light irradiation and >=1MOMEGA/mm.<2> at dark. The length of the thin film electrode at light irradiation is the sum of the lengths of the driving thin film electrodes 3a, 3b and the photoconductive film 3c, and the pass frequency band of a filter is made broad. The driving thin film electrodes 3a, 3b are insulated at dark and the pass frequency band of the filter is made narrow. |
