说明：  主要由单片机系统及显示电路、超声波发射电路和超声波检测接收电路三部分组成。采用STC89C51来实现对CX20106A红外接收芯片和7404的控制
(Mainly by the SCM system and the display circuit, ultrasonic transmitter and ultrasonic detection circuit receiving circuit consists of three parts. STC89C51 to achieve the CX20106A using infrared receiver control chip and 7404)