| 摘要 |
PURPOSE:To set the directional characteristics of an ultrasonic wave to be radiated sharp by generating driving electrodes and damping electrodes to the electrode patterns of a vertical and horizontal symmetry and generating the electrode areas to pattern forms following cos square curves. CONSTITUTION:The electrode widths of the driving electrodes 18a and 18i are generated in an areal distribution which the widths gradually decrease in correspondence with the cos square curves with directing the longitudinal direction end parts of a piezo-electric vibrator 10 with a central part driving electrode 18e as an original. The electrodes of the damping electrodes 20a and 20j are generated as the areal distribution which they gradually decrease in proportion to (1-cos square) curves with directing a central part from both end parts of the longitudinal direction. In such a constitution, the driving electrodes 18a and 18i are respectively and electrically connected and the damping electrodes 20a and 20j are respectively and electrically connected, and are connected with a back electrode. An AC power E is connected between the common connection point 22a of the driving electrodes 18a and 18i and the common connection point 22b of the damping electrodes 20a, 20j and the back electrode.
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