Sensor circuit that converts detected change value from analog to digital value
AssigneeOki Electric Industry Co., Ltd.
InventorTakayuki Kondo
Life of this patent
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Abstract
A digital-to-analog converter 41, capable of setting a voltage V41 of an offset value using information JS. At the time of an offset correction operation, the voltage V41 of the offset signal is sequentially varied to automatically set it to a value that is extremely close to a lower executable conversion limit Vbottom within the convertible range of the analog-to-digital converter. With this structure it is possible to provide a sensor circuit that is capable of preventing lowered precision with temperature variations.
Claims15
A sensing circuit having an offset voltage adjusting function, the sensing circuit outputting a sensing signal to an analog-to-digital (A/D) converter, the sensing circuit comprising:
- a sensing element having a resistance value, the resistance value variably changing in response to an amount of change in a sensing object, the object able to be shut off from the sensing element by a shutting mechanism;
- an amplifying circuit having first and second input nodes that respectively receive a first voltage and a second voltage, wherein said amplifying circuit compares the first voltage with the second voltage and outputs an analog signal amplified in accordance with the comparison result, the first voltage being generated based on the resistance value of said sensing element;
- a switching circuit that opens and closes an electrical connection of said first input node to said second input node;
- a voltage generating circuit that generates the second voltage in accordance with an offset information signal that includes a plurality of bits, said voltage generating circuit including a digital-to-analog (D/A) converter that converts the offset information signal into the second voltage;
- an output node coupled to said A/D converter, said output node supplied with said sensing signal in accordance with the first voltage and the analog signal output by said amplifying circuit;
- and
- a comparing circuit that receives and compares said sensing signal and a set monitoring voltage, and outputs a comparison signal.
A sensing circuit having an offset voltage adjusting function, the sensing circuit outputting a sensing signal to an analog-to-digital (A/D) converter, the sensing circuit comprising:
- a sensing element having a resistance value, the resistance value variably changing in response to an amount of chance in a sensing object,
- a shutting mechanism that shuts off the object able to be from the sensing element;
- an amplifying circuit having first and second input nodes that respectively receive a first voltage and a second voltage, wherein said amplifying circuit compares the first voltage with the second voltage and outputs an analog signal amplified in accordance with the comparison result, the first voltage being generated based on the resistance value of said sensing element;
- a switching circuit that opens and closes an electrical connection of said first input node to said second input node;
- a voltage generating circuit that generates the second voltage in accordance with an offset information signal that includes a plurality of bits, said voltage generating circuit including a digital-to-analog (D/A) converter that converts the offset information signal into the second voltage;
- an output node coupled to said A/D converter, said output node supplied with said sensing signal in accordance with the first voltage and the analog signal output by said amplifying circuit, and
- a comparing circuit that receives and compares said sensing signal and a set monitoring voltage, and outputs a comparison signal.
Dependencies are inferred from the claim text.