| 摘要 |
PURPOSE:To surely detect an incoming call to a receiver by comparing a power supply voltage with a reference voltage of the receiver to detect a voltage change when the incoming call is received by the receiver. CONSTITUTION:The device is provided with a quasi-stabilizing power supply 2 supplying power to a receiver 5 and a voltage comparator 4 receiving a voltage of the quasi-stabilizing power supply 2 and a reference voltage from a reference voltage generator 3 and comparing them. Since the quasi-stabilizing power supply 2 is employed, the increment of power consumption when an incoming call is received by the receiver 5 is a very small voltage change. The very small voltage change is compared with a reference voltage generated from the reference voltage generator 3 by the voltage comparator 4 to detect an incoming call. The arrival of the incoming call is detected through the change in an output of the voltage comparator 4 resulting from the change in the power supply voltage at the arrival of the call to the receiver 5 in this way. Thus, the arrival of the call to the receiver 5 is surely detected without malfunction. Moreover, no mechanical accuracy and alignment are requirements and the device is realized simply and inexpensively. |
