| 摘要 |
PURPOSE:To obtain the flat frequency characteristics, by deciding the setting position of the electrode of a piezoelectric plate so that a general offset is secured for the electric charge induced on the electrode surface of the 1st resonance. CONSTITUTION:A metallic plate uses a phosphor bronze plate having 0.15mm. thickness, 15mm. length and 8mm. width, and a piezoelectric plate made of the porcelain of zircon lead titanate group with the same size is adhered on thesingle surface of the metallic plate. Then another piezoelectric plate having 5mm. length with the same thickness and width as the first piezoelectric plate is adhered on the other surface of the metallic plate with their polarities set in the same direction. Thus a piezoelectric bimorph oscillator is obtained. Then the end part of the oscillator at the side where the shorter piezoelectric plate is adhered is fixed by adhesion to a case with 2mm. width, and a polyimide film having 28mm. diameter and 50mum thickness is formed into a conical shape at the other end part of the oscillator. This cone of film is then joined to the center of a diaphragm with its circumference end connected to the case. Thus a sound generator is obtained. In such constitution, the positive electric charge produced to the short piezoelectric plate offsets the negative electric charge produced to the long piezoelectric plate. As a result, no peak part is caused to the output characteristics of the sound generator to obtain the flat frequency characteristics. |
