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Patent Searching and Data

Document Type and Number:
Japanese Patent JPH03129102
Kind Code:

PURPOSE: To improve accuracy and reliability or an actuator by compensating a displacement error of an output plunger due to load through providing a circuit which senses displacement of the output plunger of the actuator, and also by detecting breakage of the actuator.

CONSTITUTION: A displacement sensor 5 is provided in order to detect displacement of an output plunger 4. The output of the displacement sensor 5 is fed to a displacement sensing circuit 6. The displacement sensing circuit 6 has oscillators 21 and 22 connected to two condensers having capacities of C1 and C2. The output from the oscillators is fed to a low-pass filter 26 via a mixer 25. When capacities C1 and C2 changes with the motion of an output plunger 4 oscillator circuits 23 and 24 send output signals of frequencies f1 and f2. These output signals are mixed and fed to the low-pass filter 26. Thus, the difference between C1 and C2 is shown as the difference of frequencies in the output frequency of the displacement sensing circuit 6. This output frequency is fed to a central processing unit 3 and a voltage control signal is sent to a drive circuit 2 so as to compensate a difference between the actual and required displacements.

Tsutsui, Osamu
Yoshida, Takao
Kuwabara, Hidehiko
Inoue, Shoji
Application Number:
Publication Date:
June 03, 1991
Filing Date:
October 16, 1989
Export Citation:
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International Classes:
F15B9/03; F15B7/00; F15B7/08; F15B15/28; G05D3/00; H01L41/09; (IPC1-7): F15B7/00; F15B7/08; F15B9/03; F15B15/28; G05D3/00; H01L41/09