| 摘要 |
An oscillator (2) capable of oscillating signals of specified frequencies in dipped state in liquid, comprising a diaphragm of piezoelectric material (9) having a front surface (9a), a rear surface (9b), and a side surface (9c), a first electrode (10A) installed on the front surface (9a) of the diaphragm (9), a second electrode (10B) installed on the rear surface (9b) of the diaphragm (9), and a covering material (6) for covering at least the rear surface (9b) side of the diaphragm (9), wherein an opening (14) is provided in the covering material (6), the first electrode (10A) comes into contact with the liquid with the oscillator (2) dipped in the liquid, gas is held in a space (23) formed of the rear surface (9b) and the covering material (6), and the opening (14) is allowed to communicate with the space (23), whereby, even if the liquid temperature varies, the oscillation frequencies can be stabilized in a rather short time.
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