JPS60123097U - Ultrasonic vehicle detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Brief explanation of drawings]

Figure 1 is a diagram explaining the principle of a conventional infrared light blocking vehicle sensor.
Fig. 2 is a diagram explaining the principle of an ultrasonic vehicle detector, Fig. 3 is a time chart of the same as above, and Fig. 4 is a time chart for explaining the operation of a conventional ultrasonic vehicle detector using a reflection method. FIG. 5 is a time chart for explaining the operation of a conventional ultrasonic vehicle sensor using a blocking method, and FIG. 6 is a block circuit diagram showing one embodiment of the ultrasonic vehicle sensor according to the present invention. FIG. 7 is a time chart for explaining the operation of the above circuit, and FIG. 8 is a diagram of one embodiment of the logic circuit. 1: Ceiling, 3: Road surface, 5: Vehicle, 6: Ultrasonic head, 1
4: Vehicle reflected wave reception gate, 15: Road surface reflected wave reception gate, 16: Logic circuit, 17: Output terminal, 18: Controller, P: Transmission wave, Pe: Reverberation wave, R: Vehicle reflected wave, R
,, R2: multiple reflected wave, S: road surface reflected wave, Gr: vehicle reflected wave gate pulse, GS: road surface reflected wave gate pulse.

Claims (1)

[Scope of utility model registration request] ゛ In an ultrasonic vehicle detector that emits ultrasonic waves toward the road surface and detects the presence or absence of a vehicle based on the reflected waves, a predetermined time point is detected starting from the time position when the reverberation wave of the transmitted wave emitted from the ultrasonic head disappears. The detection outputs from two gates, a vehicle reflected wave receiving gate that opens the gate for a period of time to receive vehicle reflected waves, and a road reflected wave receiving gate that receives road reflected waves, are used as input signals, and the road reflected wave receiving gate It is characterized by providing a logic circuit that determines that there is no vehicle only when there is a detection output of , and there is no detection output of the vehicle reflected wave receiving gate, and that determines that a vehicle is present in the case of other input signal states. Ultrasonic vehicle detector.