发明授权
- 专利标题: Capacitive displacement transducer
- 专利标题(中): 电容位移传感器
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申请号: US857045申请日: 1986-04-29
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公开(公告)号: US4683754A公开(公告)日: 1987-08-04
- 发明人: Terutaka Hirata , Tadashi Azegami , Atsushi Kimura , Megumi Katayama
- 申请人: Terutaka Hirata , Tadashi Azegami , Atsushi Kimura , Megumi Katayama
- 申请人地址: JPX Tokyo
- 专利权人: Yokogawa Hokushin Electric Corporation
- 当前专利权人: Yokogawa Hokushin Electric Corporation
- 当前专利权人地址: JPX Tokyo
- 优先权: JPX60-92889 19850430
- 主分类号: G01D5/24
- IPC分类号: G01D5/24 ; G01L9/00 ; G01L9/12 ; G01L19/04
摘要:
A capacitive displacement type transducer, wherein the oscillation frequency of a self-excited oscillator circuit including a pair of differential capacitors formed with a movable electrode disposed between two outer electrodes is counted by a counter, the output level of the counter is reversed each time a certain count is attained to cause the differential capacitances to be switched alternatively, and to make identical the respective reversal periods, and application voltage to be applied to the differential capacitors being controlled by an integrator, and a voltage relating to the output of the integrator being applied through a fixed impedance to the movable electrode, thereby eliminating fixed capacitances formed across the difference capacitors. Also, a voltage generated by dividing and averaging the output level of the counter by use of a certain pulse duration of a monostable circuit operating in synchronism with a counter, is used to compensate for static pressure changes. Also, a temperature sensing element is included in a converting section to perform temperature correction. The circuit may be used in a two wire transmission system. The circuit improves upon the prior art by eliminating heretofore used complex circuits, thereby increasing reliability, efficiency and reducing size.