Thickness detecting sensor

本发明公开一种检测厚度的传感器，其能够将检测介质厚度的动态范围设定得很大，而且即使按照这种方式将动态范围设定得很大，也能够准确地检测介质的厚度。本发明的检测厚度的传感器包括彼此相对设置的固定电极和可动电极、通过与介质接触来改变电极间隙的柱塞和将存储在电极间的静电电容转换成电信号来检测介质厚度的CR振荡电路和FV转换电路。柱塞的后端部与可动电极的间隙一侧的电极表面接触，可动电极相应于介质厚度的增加沿着离开固定电极的方向位移。 A thickness detecting sensor can widely set a dynamic range for detecting the thickness of a medium, and exactly detect the thickness of the medium even when the dynamic range is widely set in this way. Therefore, the thickness detecting sensor has a fixing electrode (3) covered with resist (34) and a movable electrode (4) arranged so as to be opposed to each other, a plunger (20) for changing the gap between the electrodes by coming in contact with the medium, and a CR oscillating circuit and an frequency voltage converting circuit for converting electrostatic capacity stored between the electrodes into an electric signal for detecting the thickness of the medium. The rear end portion (21) of the plunger comes in contact with the electrode face of the gap side of the movable electrode. The movable electrode is displaced in the direction separated from the fixing electrode correspondingly to the thickness of the medium.