| 摘要 |
PROBLEM TO BE SOLVED: To lessen noise components and improve the detection sensitivity by making the impressed driving voltage between a center electrode and a fixed electrode have rectangular waveform with a specified duty ratio. SOLUTION: Driving voltage with rectangular waveform is applied between a center electrode 2a and a fixed electrode 1a to generate Coulmb attractive force between the electrodes and a weight part 5 is moved in the z-axis direction to displace and vibrate a flexible substrate 2 in parallel to a fixed substrate 1. In this case, by controlling the duty ratio of the driving voltage with rectangular waveform is controlled to be about 0.4 or lower, strain of the sinusoidal vibration can be improved and the noise components overlaid on the measured signal of the electrostatic capacity between electrodes are significantly lessened and the detection sensitivity is improved. In the case where the duty ratio of the driving voltage is made too small, the driving energy also becomes low and the voltage amplitude is needed to be high, and due to that, the duty ratio is set to be within the range from about 0.1 to 0.4. |
