JPH03189799A - Ultrasonic vehicle detecting device - Google Patents

Abstract

PURPOSE:To surely detect a vehicle without causing a malfunction even under such an environment as a structure exists in the upper part of an ultrasonic transmitter-receiver such as in a tunnel and under an elevated road, etc., by providing a reflecting plate provided at an oblique angle against the road surface on the upper part of the ultrasonic transmitter-receiver. CONSTITUTION:A reflecting plate 13 is attached at an angle of 45 degrees against the road surface 12 to the upper part of an ultrasonic transmitter- receiver 1. An emitted wave 9 sent out of the ultrasonic transmitter-receiver 1 is reflected by the road surface 12, and thereafter, reflected by the reflecting plate 13 and sent out in the direction being different from the road surface 12, therefore, generation of a multipath reflection between the road surface 12 and the upper structure 15 of the ultrasonic transmitter-receiver 1 can be prevented. In such a way, even under such an environment as a tunnel, etc., in which the structure exists in the upper part of the ultrasonic transmitter- receiver, the passing vehicle can be detected surely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ultrasonic vehicle detection device installed in an environment where structures exist above the road surface, such as inside a tunnel or under an elevated road.

BACKGROUND OF THE INVENTION FIG. 2 shows the configuration of a conventional ultrasonic vehicle detection device. In FIG. 2, 1 is an ultrasonic transceiver, 2 is a connection cable, and 3 is a vehicle detection unit. The ultrasonic transceiver 1 and the vehicle detection unit 3 are connected via a connection cable 2. 4 is an ultrasonic wave transmitter, 5 is a matching transformer, 6 is a reception amplifier, 7 is a level detector, and 8 is a signal processor. 9 is an ultrasonic emission wave from the ultrasonic transceiver 1, and 10 is an ultrasonic reflected wave from the vehicle 11 or the road surface 12.

FIG. 3 shows a timing chart of ultrasonic transmission and reception in the ultrasonic vehicle detection device. In Figure 3,
21 is an ultrasonic emission wave, 22 is a vehicle reflected wave reception gate for receiving reflected waves from the vehicle 11, and 23
is a reflected wave from the road surface 12, and 24 is a reflected wave from the vehicle 11.

Next, the operation of the above conventional example will be explained. In FIG. 2, a signal sent from the ultrasonic transmitter 4 is sent to the ultrasonic transceiver 1 via a matching transformer 5 and a connecting cable 2. The ultrasonic transmitter/receiver 1 converts an electric signal into an ultrasonic wave and emits it as an emitted wave 9. The emitted wave 9 is reflected by the road surface 12 when the vehicle 11 is not present, and is reflected by the vehicle 11 when the vehicle 11 is present, and is received by the ultrasonic transceiver 1 as a reflected wave 10. The received reflected wave 10 is converted into an electrical signal by the ultrasonic transceiver 1, and is sent to the reception amplifier section 6 via the connection cable 2 and matching transformer 5, where it is amplified and the level is detected by the level detection section 7. The signals are compared and input to the signal processing section 8.

The timing of transmitting and receiving ultrasonic waves at this time will be explained with reference to FIG. As shown in the figure, the ultrasonic reflected waves 21 are sent out intermittently, and when the vehicle 11 is not present, the road surface reflected waves 21 are transmitted intermittently.
Only 3 are received. When the vehicle 11 is present, a vehicle reflected wave 24 is received, and this vehicle reflected wave 24 is valid only when received within the time T set by the vehicle reflected wave reception gate 22. Therefore, the road surface reflected wave 23 when the vehicle 11 is not present is transmitted to the vehicle reflected wave receiving gate 22.
will be received outside.

Problems to be Solved by the Invention However, the conventional ultrasonic vehicle detection device described above has the following problems:
If there is a structure above the ultrasonic transceiver 1, such as inside a tunnel or under an elevated road, the emitted waves 9 sent out from the ultrasonic transceiver 1 will be partially reflected by the road surface 12. Most of the energy that enters the ultrasonic transceiver 1 travels further upwards, is reflected by the upper structure, is reflected again on the road surface 12, and then enters the ultrasonic transceiver 1. Conventional ultrasonic vehicle detection devices do not have any means for attenuating such multiple reflections, so when multiple reflected waves enter the vehicle reflected wave reception gate 22, they are detected as a vehicle. There was a problem with putting it away.

The present invention solves such conventional problems, and aims to provide an ultrasonic vehicle detection device that can prevent multiple reflected waves generated between the road surface and the structure above the ultrasonic transmitter/receiver. purpose.

Means for Solving the Problems In order to achieve the above object, the present invention includes the following steps: a reflector is attached to the upper part of the ultrasonic transceiver at an angle oblique to the road surface;
This is designed to prevent multiple reflections that occur between the road surface and the structure above the ultrasonic transceiver.

Therefore, according to the present invention, by providing a reflector on the top of the ultrasonic transceiver at an angle oblique to the road surface, it is possible to change the direction of reflected waves from the road surface and prevent multiple reflections. This has the effect that passing vehicles can be reliably detected even in environments such as tunnels where there is a structure above the handset.

Embodiment FIG. 1 shows the structure of an embodiment of the present invention, which has the same structure as the conventional example shown in FIG. 2, so similar elements are given the same reference numerals. In Figure 1, 1
2 is an ultrasonic transceiver, 2 is a connection cable, and 3 is an original image detection unit. The ultrasonic transceiver 1 and the vehicle detection unit 3 are connected via a connection cable 2. 4 is an ultrasonic transmitting section, 5 is a matching transformer, 6 is a receiving amplifying section,
7 is a level detection section, and 8 is a signal processing section.

9 is an ultrasonic emission wave from the ultrasonic transceiver 1, and 10 is an ultrasonic reflected wave from the vehicle 11 or the road surface 12.

Further, reference numeral 13 denotes a reflecting plate, which is attached above the ultrasonic transceiver 1 at an angle of 45 degrees with respect to the road surface 12. 14 is a road surface reflected wave reflected by the reflector 13;
15 is a superstructure such as a ceiling in a tunnel or an elevated road.

Next, the operation of the above embodiment will be explained. In the above embodiment, the signal sent from the ultrasonic transmitter 4 is sent to the ultrasonic transceiver 1 via the matching transformer 5 and the connection cable 2. The ultrasonic transmitter/receiver 1 converts an electric signal into an ultrasonic wave and emits it as an emitted wave 9. The emitted wave 9 is reflected by the road surface 12 when the vehicle 11 is not present, and when the vehicle 11 is present, the emitted wave 9 is reflected by the vehicle 11 as a reflection 17 and is received by the ultrasonic transceiver 1 as a reflected wave 10. The received reflected wave 10 is converted into an electric signal by the ultrasonic transceiver 1 and input to the reception amplifier section 6 via the connection cable 2 and matching transformer 5, where it is amplified and the level is detected by the level detection section 7. The signals are compared and input to the signal processing section 8.

Although some of the reflected waves 10 reflected by the road surface 12 are received by the ultrasonic transceiver 1, the majority of the others travel further upwards and are reflected by the reflector 13, becoming reflected waves 14 that reach the road surface 1.
2, it attenuates and disappears along the way. Therefore, multiple reflections by the upper structure 15 do not occur.

In this way, according to the above embodiment, the emitted wave 9 sent out from the ultrasonic transceiver 1 is reflected by the road surface 12, then reflected by the reflector plate 13, and is sent out in a direction different from the road surface 12. This has the advantage that multiple reflections between the road surface 12 and the upper structure 15 of the ultrasonic transceiver 1 can be prevented.

In the above embodiment, the reflector 13 is attached at an angle of 45 degrees with respect to the road surface 12, but the same effect can be obtained even if the angle is set to 20 degrees. , select and use the optimal angle depending on the performance of the device, surrounding conditions, etc.

Effects of the Invention As is clear from the above embodiments, the present invention provides a reflector on the top of the ultrasonic transceiver at an angle oblique to the road surface, and changes the direction of reflection of waves reflected from the road surface using the reflector. This has the advantage of being able to prevent multiple reflections from occurring between the road surface and the superstructure. Therefore, even in an environment where there is a structure above the ultrasonic transceiver, such as inside a tunnel or under an elevated road, it is possible to reliably detect a vehicle without malfunction.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of an ultrasonic vehicle detection device according to an embodiment of the present invention, FIG. 2 is a schematic block diagram of a conventional ultrasonic vehicle detection device, and FIG. 3 is a conventional ultrasonic vehicle detection device. It is a timing chart of ultrasonic transmission and reception in the device. 1... Ultrasonic transceiver, 2... Connection cable, 3...
・Vehicle detection unit, 4... Ultrasonic sending unit, 5...
Matching transformer, 6... Reception amplifier section, 7... Level detection section, 8... Signal processing section, 9... Ultrasonic emission wave, 1
0...Ultrasonic reflected wave, 11...Vehicle, 12...Road surface, 13...Reflector plate, 14...Road surface reflected wave reflected by the reflector plate, 15...Superstructure, 21...Emitted wave, 22...Vehicle reflected wave reception gate, 23...Road surface reflected wave, 24...Vehicle reflected wave.

Claims (1)

[Claims] An ultrasonic vehicle detection device equipped with a reflector mounted on the top of an ultrasonic transceiver at an angle to the road surface.