Sensor test circuit of an alarm system
First Claim
1. In an alarm system having a transmission line, a plurality of sensor terminal units each having a sensor connected to one end of the transmission line in a distributed manner and a receiver means connected to the other end of the transmission line for addressing various ones of the plurality of terminal units to receive an alarm signal therefrom and for sending a test instruction signal thereto, wherein the improvement comprises:
- each terminal unit having a test voltage generator means connected to said sensor for changing an analog output voltage of the sensor by a predetermined amount for testing operation of the terminal unit; and
control circuit means responsive to the test instruction signal for activating said test voltage generator means.
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Accused Products
Abstract
When a receiver supplies both an address signal and a test instruction signal to a given terminal unit, a test voltage generator forming a sensor test circuit of this terminal unit supplies a predetermined test voltage to a corresponding sensor. This sensor generates an analog signal obtained by superimposing the test voltage on the normally detected voltage. The analog signal is A/D-converted, and a resultant digital signal is received by the receiver, thereby allowing a test for operating conditions of any sensor at the site of the receiver. The test voltage generator may generate a plurality of stepwise voltage components to readily check operating characteristics (e.g., overload characteristic) of the sensor.
19 Citations
8 Claims
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1. In an alarm system having a transmission line, a plurality of sensor terminal units each having a sensor connected to one end of the transmission line in a distributed manner and a receiver means connected to the other end of the transmission line for addressing various ones of the plurality of terminal units to receive an alarm signal therefrom and for sending a test instruction signal thereto, wherein the improvement comprises:
- each terminal unit having a test voltage generator means connected to said sensor for changing an analog output voltage of the sensor by a predetermined amount for testing operation of the terminal unit; and
control circuit means responsive to the test instruction signal for activating said test voltage generator means. - View Dependent Claims (2, 3)
- each terminal unit having a test voltage generator means connected to said sensor for changing an analog output voltage of the sensor by a predetermined amount for testing operation of the terminal unit; and
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4. An alarm system test circuit responsive to a test instruction signal received from a remote control unit, comprising:
- control circuit means for recognizing a test instruction signal received from the remote unit;
sensor means for detecting smoke, heat, or other alarm inducing parameters and having an analog voltage output indicative of an alarm parameter being sensed; and
test voltage generator means activated by the control circuit means and connected to the sensor means for causing a predetermined analog voltage change from the sensor means useful in testing operation of an alarm system associated with the sensor means. - View Dependent Claims (5)
- control circuit means for recognizing a test instruction signal received from the remote unit;
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6. A test circuit of an alarm system formed of a transmission line, a plurality of terminal units connected to one end of said transmission line in a distributed manner, a receiver connected to the other end of said transmission line, each of said plurality of terminal units including a sensor connected to an amplifier, and an A/D converter connected to an interface, said test circuit comprising:
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a test voltage generator which has a series circuit of a first resistor, a first transistor, and a second resistor, said series circuit being connected between positive and negative power source terminals; a control circuit means for activating the test voltage generator; an analog output generated by said sensor which comprises a test voltage and a normally detected voltage, and which is converted into a digital output by said A/D converter, and a digital output therefrom being supplied to said receiver when said receiver supplies an address signal and a test instruction signal to a corresponding one of said terminal units. - View Dependent Claims (7, 8)
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Specification