| 摘要 |
PURPOSE:To form traveling waves whose wave number is one or more in the circumferential direction by a method wherein a plurality of first piezoelectric-element sheets which are arranged in the circumferential direction at intervals of an odd multiple of a 1/4 wavelength and second piezoelectric-element sheets in which electrode parts have been formed on the whole of one side of a piezoelectric ceramic are disposed alternately. CONSTITUTION:A GND electrode 14G with a length of a 1/4 wavelength is formed in the circumferential direction on a piezoelectric-element sheet (PE) 4 at the outermost layer. Power-supply electrodes 14A, 14B for an A-phase and a B-phase are formed on both sides of the GND electrode 14G. In a PE sheet 2 as a second sheet from the upper part, a PE 2 as a fourth sheet and a PE 3 in the lowermost layer, first electrodeless parts 15-1 in which an electrode with a length of a 3/4 wavelength is not formed are formed so as to be identical to the center in the circumferential direction of the GND electrode 14G of the PE 4. In addition, second electrodeless parts 15-1 in which an electrode with a length of a 1/4 wavelength is not formed are formed in symmetric positions of the first electrodeless parts 15-1. Then, positive and negative electrodes 12A, 13A, 12B, 13B for an A-phase and a B-phase which has a length of a 1/2 wavelength are formed on both sides between both electrodeless parts. |
