Sensor circuit
First Claim
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1. A sensor circuit comprising:
- sensing means that produces detection signals;
voltage conversion means that subjects the detection signals to voltage conversion to produce a conversion voltage;
AC component pickup means that receives the conversion voltage and picks up an AC component in the conversion voltage;
first adder means that provides an upper-limit voltage by adding an upper-limit threshold value to the AC component;
second adder means that provides a lower-limit voltage by adding a lower-limit threshold value smaller than the upper-limit threshold value to the AC component; and
detecting means that detects an abnormal offset voltage depending upon whether the conversion voltage is in a range of normal voltages between the upper-limit voltage and the lower-limit voltage.
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Abstract
A sensor circuit includes an AC component pickup circuit and first and second adder circuits or first and second high-pass filters, and specifies a range of normal voltages by an upper-limit voltage formed by adding an upper-limit threshold value to the AC component in the input voltage and by a lower-limit voltage formed by adding a lower-limit threshold value to the AC component in the input voltage. An abnormal offset voltage is detected by judging whether the output voltage of an inverting amplifier circuit is lying in the range of normal voltages.
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Citations
7 Claims
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1. A sensor circuit comprising:
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sensing means that produces detection signals;
voltage conversion means that subjects the detection signals to voltage conversion to produce a conversion voltage;
AC component pickup means that receives the conversion voltage and picks up an AC component in the conversion voltage;
first adder means that provides an upper-limit voltage by adding an upper-limit threshold value to the AC component;
second adder means that provides a lower-limit voltage by adding a lower-limit threshold value smaller than the upper-limit threshold value to the AC component; and
detecting means that detects an abnormal offset voltage depending upon whether the conversion voltage is in a range of normal voltages between the upper-limit voltage and the lower-limit voltage. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A sensor circuit comprising:
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a processing circuit for processing a detection signal of a sensor applied thereto to determine a physical quantity detected by the sensor; and
a diagnosis circuit for detecting an abnormality in the detection signal, wherein the diagnosis circuit includes an AC component pickup circuit that picks up AC component in the detection signal, a first adder circuit that provides a first reference signal variable with the AC component by adding the AC component and a predetermined first signal, a second adder circuit that provides a second reference signal variable with the AC component by adding the AC component and a predetermined second signal different from the first signal, and a comparison circuit that compares the detection signal with the first reference signal and the second reference signal, thereby detecting the abnormality when the detection signal is outside the first reference signal and the second reference signal.
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Specification