Linear magnetic shaft position sensor monitoring changes in the inductance in a coil
AssigneeSony Corporation
InventorYasumasa Kyodo
Life of this patent
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Abstract
A shaft position detection device for detecting a certain position on a shaft comprising: a movable shaft including a detection portion to be detected, a characteristic of which is different from the other portions; a position detection coil to which the movable shaft is freely inserted; an inductance detecting means for detecting changing of inductance between a case of the movable shaft being in the position detection coil and a case of the movable shaft being out of the position detection coil; in which a position of the detection portion in response to the changing of the inductance. The difference of the magnetic characteristic is defined by a cross section area of the shaft, winding a magnetic tape, forming a magnetic layer.
Claims7
A shaft position detection device comprising:
- a movable shaft including a detection portion to be detected, a characteristic of which is different from other portions of said movable shaft;
- a position detection coil into which said movable shaft is freely inserted;
- an inductance detecting means connected to the position detection coil for detecting a change in inductance between a case of said detection portion being in said position detection coil and a case of said detection portion being out of said position detection coil;
- wherein a position of said detection portion is detected in response to said change in inductance;
- wherein said inductance detecting means includes:
- an oscillation portion using said position detection coil as an inductance element, and generating an output signal having an oscillation frequency corresponding to the inductance of the inductance element;
- a period detection portion for detecting a period of the output signal of said oscillation portion;
- a comparison and detection portion for comparing the period detected by said period detection portion with a predetermined threshold value, and for detecting a change in the inductance according to the output of the comparison.
A shaft position detection device comprising:
- a movable magnetic shaft including a detection portion to be detected, a characteristic of which is different from all other portions;
- an edge formed by a change in the cross section area of said movable shaft at a boundary between said detection portion and the other portions;
- a position detection coil into which said movable shaft is freely inserted;
- an inductance detecting means connected to the position detection coil for detecting the change in inductance between a case of said detection portion being in said position detection coil and a case of said detection portion being out of said position detection coil;
- wherein a position of said detection portion is detected in response to the changing of said inductance;
- wherein said inductance detecting means includes:
- an oscillation portion using said position detection coil as an inductance element, and generating an output signal having an oscillation frequency corresponding to the inductance of the inductance element;
- a period detection portion for detecting a period of the output signal of said oscillation portion;
- a comparison and detection portion for comparing the period detected by said period detection portion with a predetermined threshold value, and for detecting a change in the inductance according to the output of the comparison.
Dependencies are inferred from the claim text.