JPS5522175A - Sensor circuit - Google Patents

Abstract

PURPOSE: To highly accurately detect the value of a sensor during the operation of a meter by applying a constant current to a sensor resistor which is connected with the meter to be driven at a constant voltage by a bimetal.

CONSTITUTION: When a switch 2 is closed, a current is supplied through the switch 32 of a closed meter 3 from a power source 1 to a voltage adjusting bimetal 31 and an indicating bimetal 33. The bimetal 31 turns on and off the switch 32 in accordance with the voltage of the power source 1 so that the meter 3 effects the drive at the preset voltage even in case the supply voltage of an automobile or the like is high. If the closure of the switch 32 is detected by the detecting circuit 42 of a sensor circuit 4, the constant current from a constant current source 41 is supplied a variable resistance sensor 34 which is in series with the bimetal 33. Thus, the both terminal voltages of the resistor 34 are detected in a high accuracy during the operation of the meter 3 by a potential detector 43 of the circuit 4. Incidentally, if the potential of the capacitor to be charged with the constant current output is compared with the detected potential of a runner electrode, the digital detection can be accomplished with the use of the digital detection.

COPYRIGHT: (C)1980,JPO&Japio