| 摘要 |
PURPOSE:To reduce the difference of the buzzer sound pressure for an electronic wristwatch when it is worn on the wrist and when not, by bonding a piezoelectric element on the case back of the watch and setting the number of natural oscillations of the piezoelectric element within a specified frequency range. CONSTITUTION:The piezoelectric element 2 is bonded to the case back 5 to form a piezoelectric buzzer. If the natural oscillation f0 of this buzzer is set at 6kHz- 7.5kHz, the peak of the sound pressure is formed at the 1/integer position of the oscillation f0 as well as at the position of the oscillation f0. Then the piezoelectric buzzer is driven at a frequency of 4096Hz with which the difference of sound pressure is reduced when the watch is worn on the wrist and when not. |
