Step-down transformer utilizing the piezoelectric transversal effect

Almost all piezoelectric transformers are used for step-up-type transformers and they are seldom used for step-down-type transformers. We have developed a novel step-down piezoelectric transformer utilizing the piezoelectric transversal effect. As this transformer can be driven with lower frequency than that utilizing the piezoelectric longitudinal effect, the driving circuit should be simple and the layout of input/output units should be easy. For example, when applied to a piezoelectric transformer utilizing rectangular piezoelectric ceramics with longitudinal expansion vibration mode, the gain of the transformer is controllable in the range of 0.1 to 1.0 just by controlling the ratio of the number of input/output layers. The maximum output power is 18 W/cm(3) with 90% efficiency. Moreover, spurious vibrations such as slide mode and torsional mode can be inhibited by the layout of the input/output layers. (C) 1998 Scripta Technica.