| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a comparator circuit, an ultrasonic receiving circuit, an ultrasonic transmitting/receiving circuit and an object detector for a visually handicapped person, which are a accelerated in switching operation compared with a comparator circuit using a comparator and made inexpensive by constituting the comparator circuit by using an inverter. SOLUTION: The receiving part of the ultrasonic transmitting/receiving circuit to be used for the object detector is composed of a receiving amplifier 14 and a comparator circuit 15, and this comparator circuit is composed of a CMOS inverter Inv9, a power source 30 for inputting the signal of a prescribed level to the input terminal of this inverter and resistors R21 and R22. When a transistor Tr7 is turned off, the input terminal of the inverter is made a little lower than the threshold voltage and at such a time, when a signal greater than the difference between that level and this threshold voltage is inputted from the receiving amplifier to the input terminal, a received signal is outputted. The inverter is composed of one IC component together with an inverter used for the other circuits.</p> |
