JPS6479732A - Crossed comb type electrode pair - Google Patents

Abstract

PURPOSE:To set a wide specific frequency band of surface acoustic waves and to reduce electric power consumption in a wide deflection angle range by inserting inductances which prohibit the action of electrode fingers as capacitors between electrode base parts and the electrode fingers connected to the electrode base parts. CONSTITUTION:A chirp crossed electrode pair 15 is formed by arraying the many electrode fingers 15A to a comb tooth shape and connecting every other electrode fingers to one electrode base part 15B and the other electrode base part 15C. The electrode fingers are so formed that the line width thereof changes gradually and the inter-electrode finger spacing changes correspondingly at chirp periods. In addition, the direction of the electrode fingers is gradually changed as well. Microcoils M1, M2,...Mn are inserted between the electrode fingers 15A connected to the electrode base part 15B and the electrode base part 15C. The respective coils prohibit the electrode fingers to act as the capacitors when the alternating voltages of the frequencies except the frequencies to generate the surface acoustic waves from the electrode fingers are impressed to said coils. The specific frequency band of the surface acoustic wave is thus set wide and the electric consumption is reduced in the wide deflection angle range.