Resistor sensor input apparatus
AssigneeKabushiki Kaisha Toshiba
InventorYosimori Obata
Life of this patent
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Abstract
Disclosed is an apparatus for detecting a resistance value of a resistor sensor through three signal lines with high detection accuracy. In the apparatus, a reference resistance element is inserted in a current path of a reference current, first and second voltages across the ground and first and second signal lines are respectively held in first and second holding portions and a third voltage across the terminals of a reference resistance element is held in a third holding portion. The first and second voltages held in the first and second holding portions are output simultaneously and the third voltage held in the third holding portion is output at a timing different from the timing when the first and second voltages are output. A differential amplifier detects the third voltage and a differential voltage.
Claims17
An apparatus for detecting a resistance value of a resistor sensor to which a reference current is supplied, and inputting a detected resistance to an external device said apparatus comprising:
- a first signal line connecting a first end of the resistor sensor and a first contact terminal provided in the apparatus;
- a second signal line connecting a second end of the resistor sensor and a second contact terminal provided in the apparatus;
- a third signal line connecting the second end of the resistor sensor and a third contact terminal provided in the apparatus;
- a reference resistance element having a first end connected to the third contact terminal and a second end connected to a ground;
- a reference current source for supplying the reference current to the first signal line through the first contact terminal;
- a first voltage holding means for holding a voltage E.sub.1 across the first signal line and the ground;
- a second voltage holding means for holding a voltage E.sub.2 across the second signal line and the ground;
- a third voltage holding means for holding a voltage E.sub.3 across the first and second ends of the reference resistance element;
- a differential amplifier, having first and second input terminals, for detecting the voltage E.sub.3 held by the third voltage holding means and detecting a differential voltage E.sub.def corresponding to a difference between the voltage E.sub.1 held by the first voltage holding means and a voltage E.sub.2 held by the second voltage holding means, obtained by amplifying the voltage E.sub.2 with a gain corresponding to resistance of the first and second signal lines;
- and
- switching means, inserted between the differential amplifier and the first to third voltage holding means, for connecting the third voltage holding means to the first input terminal of the differential amplifier, when the voltage E.sub.3 is detected by the differential amplifier, and respectively connecting the first and second voltage holding means to the first and second input terminals of the differential amplifier, when the voltage E.sub.def is detected by the differential amplifier.
An apparatus for causing a reference current to flow through a plurality of resistor sensors and measuring resistance values of the respective resistor sensors, said apparatus comprising:
- a plurality of measuring units respectively corresponding to the resistor sensors;
- a plurality of first signal lines, each connecting a first end of each of the resistor sensors and a first contact terminal of each of the measuring units;
- a plurality of second signal lines, each connecting a second end of each of the resistor sensors and a second contact terminal of each of the measuring units;
- a plurality of third signal lines, each connecting the second end of each of the resistor sensors and a third contact terminal of each of the measuring units;
- a plurality of reference resistance elements, provided in the respective measuring units, each having a first end connected to the third contact terminal of a corresponding measuring unit and a second end connected to the ground;
- a plurality of reference current sources, provided in the respective measuring units, for supplying the reference current to the first signal lines through the first contact terminals;
- a plurality of first voltage holding means, provided in the respective measuring units, for holding a voltage E.sub.1 across the respective first signal lines and the ground;
- a plurality of second voltage holding means, provided in the respective measuring units, for holding a voltage E.sub.2 across the respective second signal lines and the ground;
- a plurality of third voltage holding means, provided in the respective measuring units, for holding a voltage E.sub.3 across the first and second ends of the respective reference resistance elements;
- a differential amplifier, having first and second input terminals, for detecting the voltage E.sub.3 held by each of the third voltage holding means and detecting a differential voltage E.sub.def corresponding to a difference between the voltage E.sub.1 held by the first voltage holding means and a voltage E.sub.2 held by the second voltage holding means, with a gain corresponding to resistance values of the first and second signal lines;
- switching means, provided for the respective measuring units and inserted between the differential amplifier and the first to third voltage holding means of the respective measuring units, for connecting the third voltage holding means to the first input terminal of the differential amplifier, when the voltage E.sub.3 is detected by the differential amplifier, and respectively connecting the first and second voltage holding means to the first and second input terminals of the differential amplifier, when the voltage E.sub.def is detected by the differential amplifier;
- and
- time-divisional driving means for driving the switching means of the respective measuring units in a time divisional manner, so that the voltage E.sub.3 and the differential voltage E.sub.def of every measuring unit are detected by the differential amplifier.
Dependencies are inferred from the claim text.