| 摘要 |
PURPOSE:To obtain a miniature multi-mold filter which has a wide band characteristics and can be used in a range of 500kHz-1MHz, by attaching a set of electrodes made of a constant elastic metal with a space decided by the pass band width to the lengthwise counter surfaces of a rectangular piezoelectric ceramics having the residual polarization in the lengthwise direction and utilizing the vertical effect. CONSTITUTION:Constant elastic metallic electrodes (elinvar, etc.) 2, 2' and 2'' are fixed on both sides of a rectangular piezoelectric ceramics 1 having a residual polarization 3 in the lengthwise direction and utilizing the vertical effect by means of an adhesive like solder, etc. An input signal of a pass band frequency is impressed between input side electrodes 5 and 5' of such a filter from an oscillator 4. Thus the vibrations of a thickness slip mode are generated between input side electrodes 2 and 2'', and the vibration energy is enclosed under electrodes by a mass load effect of the electrodes. In the same way, the vibration energy is also enclosed under an area between output side electrodes 2' and 2''. Thus this filter can be used in a wide band of frequencies owing to use of the piezoelectric ceramics having a large electric-mechanical coupling coefficient as a piezoelectric material. |
