Unit for sensing physical quantity
First Claim
1. An alarm unit incorporated in an electric system to which a power voltage is supplied, the alarm unit comprising:
- a first voltage evaluation circuit, which determines whether or not the power voltage is lower than a first predetermined voltage and outputs a first accident state signal when the power voltage is lower than the first predetermined voltage, the first voltage evaluation circuit being operable only when the power voltage is higher than a second predetermined voltage, the first predetermined voltage being higher than the second predetermined voltage;
a second voltage evaluation circuit, which determines whether or not the power voltage is equal to or lower than the second predetermined voltage, and outputs a second accident state signal when the power voltage is equal to or lower than the second predetermined voltage, the second voltage evaluation circuit being operable when the power voltage is between a third predetermined voltage and the second predetermined voltage, the second predetermined voltage being higher than the third predetermined voltage; and
an output circuit, which outputs an alarm signal in response to either of the outputted first or second accident state signals.
1 Assignment
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Accused Products
Abstract
A sensor unit sensing a physical quantity comprises a first voltage evaluation circuit, a second voltage evaluation circuit, an alarm signal output circuit, and a sensor output circuit. The first voltage evaluation circuit evaluates a power voltage by comparing it with a reference voltage and outputs an accident signal when the power voltage is lower than a first predetermined voltage. The second voltage evaluation circuit working in a lower voltage range in which the first voltage evaluation circuit is insensitive outputs the accident signal when the power voltage is lower than a second predetermined voltage. The alarm signal output circuit outputs an alarm signal in response to the accident signal. The sensor output circuit outputs a sensor signal and inhibits the circuit from outputting the sensor signal in response to the accident signal, so that the alarm signal output circuit provides the alarm signal in response to the accident signal.
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Citations
13 Claims
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1. An alarm unit incorporated in an electric system to which a power voltage is supplied, the alarm unit comprising:
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a first voltage evaluation circuit, which determines whether or not the power voltage is lower than a first predetermined voltage and outputs a first accident state signal when the power voltage is lower than the first predetermined voltage, the first voltage evaluation circuit being operable only when the power voltage is higher than a second predetermined voltage, the first predetermined voltage being higher than the second predetermined voltage; a second voltage evaluation circuit, which determines whether or not the power voltage is equal to or lower than the second predetermined voltage, and outputs a second accident state signal when the power voltage is equal to or lower than the second predetermined voltage, the second voltage evaluation circuit being operable when the power voltage is between a third predetermined voltage and the second predetermined voltage, the second predetermined voltage being higher than the third predetermined voltage; and an output circuit, which outputs an alarm signal in response to either of the outputted first or second accident state signals. - View Dependent Claims (10)
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2. A sensor unit incorporated in an electric system to which a power voltage is supplied, the sensor unit having a sensor circuit sensing a physical quantity to output a sensor signal responding to the sensed physical quantity, comprising:
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a first voltage evaluation circuit, which determines whether or not the power voltage is lower than a first predetermined voltage and outputs a first accident state signal when the power voltage is lower than the first predetermined voltage, the first evaluation circuit being operable only when the power voltage is higher than a second predetermined voltage, the first predetermined voltage being higher than the second predetermined voltage; a second voltage evaluation circuit, which determines whether or not the power voltage is equal to or lower than the second predetermined voltage, and outputs a second accident state signal when the power voltage is equal to or lower than the second predetermined voltage, the second voltage evaluation circuit being operable when the power voltage is between a third predetermined voltage and the second predetermined voltage, the second predetermined voltage being higher than the third predetermined voltage; and an output circuit, which outputs an alarm signal in response to either of the outputted first or second accident state signals. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 11, 12, 13)
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Specification