JP2596839B2 - Ultrasonic vehicle detection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic vehicle detection device that is installed in an environment where a structure exists above a road surface, such as in a tunnel or under an elevated road.

2. Description of the Related Art FIG. 2 shows a configuration of a conventional ultrasonic vehicle detection device. In FIG. 2, 1 is an ultrasonic transmitter / receiver, 2 is a connection cable, and 3 is a vehicle detection unit. The ultrasonic transmitter / receiver 1 and the vehicle detection unit 3 are connected via a connection cable 2. Reference numeral 4 denotes an ultrasonic transmission unit, 5 denotes a matching transformer, 6 denotes a reception amplification unit, 7 denotes a level detection unit, and 8 denotes a signal processing unit. 9 is an ultrasonic wave emitted from the ultrasonic transmitter / receiver 1, and 10 is a reflected wave of the ultrasonic wave from the vehicle 11 or the road surface 12.

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

Next, the operation of the above conventional example will be described. In FIG. 2, the signal transmitted from the ultrasonic transmission unit 4 is transmitted 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 emission wave 9. The emitted wave 9 is reflected by the road surface 12 when the vehicle 11 is not present, 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 electric signal by the ultrasonic transmitter / receiver 1, input to the reception amplifier 6 via the connection cable 2 and the matching transformer 5, amplified there, and the level is detected by the level detector 7. The signals are compared and input to the signal processing unit 8.

The timing of transmission and reception of ultrasonic waves at this time will be described with reference to FIG. As illustrated, the ultrasonic reflected wave 21 is intermittently transmitted, and when the vehicle 11 does not exist, only the road surface reflected wave 23 is received. If the vehicle 11 is present, the vehicle reflected wave
24, and the 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 does not exist is received outside the vehicle reflected wave reception gate 22.

Problems to be Solved by the Invention However, in the above-described conventional ultrasonic vehicle detection device, the ultrasonic transmitter / receiver 1 is used as in a tunnel or under an elevated road.
When there is a structure on the upper part, the emitted wave 9 transmitted from the ultrasonic transmitter / receiver 1 is reflected on the road surface 12 and then partially enters the ultrasonic transmitter / receiver 1, but most of the emitted wave 9 is located above the ultrasonic wave 9. Then, the light is reflected on the upper structure, reflected on the road surface 12 again, and then enters the ultrasonic transceiver 1. For such multiple reflections, the conventional ultrasonic vehicle detection device does not have any attenuating means, so when a multiple reflection wave enters the vehicle reflection wave reception gate 22, it is detected as a vehicle. There was a problem that it would.

The present invention solves such a conventional problem, and provides an ultrasonic vehicle detection device that can prevent multiple reflected waves generated between a road surface and a structure above an ultrasonic transceiver. Aim.

Means for Solving the Problems In order to achieve the above object, the present invention provides a structure in which a reflector is attached to an upper part of an ultrasonic transmitter / receiver at an oblique angle with respect to a road surface, and the road surface and the upper part of the ultrasonic transmitter / receiver are provided. This is to prevent multiple reflections occurring between them.

Effects Therefore, according to the present invention, by providing a reflector at an oblique angle with respect to the road surface above the ultrasonic transmitter / receiver, it is possible to change the direction of the reflected wave from the road surface and prevent multiple reflections. Even in an environment such as a tunnel where a structure exists above the handset, an effect that a passing vehicle can be reliably detected.

Embodiment FIG. 1 shows a configuration of an embodiment of the present invention.
Since it has the same configuration as the conventional example shown in FIG. 2, the same reference numerals are given to the same elements. In FIG.
1 is an ultrasonic transceiver, 2 is a connection cable, and 3 is a vehicle detection unit. The ultrasonic transmitter / receiver 1 and the vehicle detection unit 3 are connected via a connection cable 2. Reference numeral 4 denotes an ultrasonic transmission unit, 5 denotes a matching transformer, 6 denotes a reception amplification unit, 7 denotes a level detection unit, and 8 denotes a signal processing unit. 9 is an ultrasonic wave emitted from the ultrasonic transmitter / receiver 1, and 10 is a reflected wave of the ultrasonic wave from the vehicle 11 or the road surface 12. Reference numeral 13 denotes a reflection plate, which is mounted at a position 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, and 15 is an upper structure such as a ceiling in a tunnel or an elevated road.

Next, the operation of the above embodiment will be described. In the above embodiment, the signal transmitted from the ultrasonic transmitter 4 is transmitted 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 emission wave 9. The emitted wave 9 is reflected by the road surface 12 when the vehicle 11 is not present, 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 electric signal by the ultrasonic transmitter / receiver 1, input to the reception amplifier 6 via the connection cable 2 and the matching transformer 5, amplified there, and the level is detected by the level detector 7. The signals are compared and input to the signal processing unit 8.

A part of the reflected wave 10 reflected by the road surface 12 is received by the ultrasonic transmitter / receiver 1, but most of the other wave goes further upward and is reflected by the reflecting plate 13 to become a reflected wave 14 and become a reflected wave 14. It goes parallel to and attenuates and disappears on the way. Therefore, multiple reflection by the structure 15 does not occur.

As described above, according to the above embodiment, the emission wave 9 transmitted from the ultrasonic transmitter / receiver 1 is reflected by the road surface 12 and then reflected by the reflector plate.
Since the light is reflected at 13 and transmitted in a direction different from that of the road surface 12, there is an advantage that occurrence of 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 mounting angle of the reflector 13 is set to 45 degrees with respect to the road surface 12, but the same effect can be obtained by setting the angle to 20 degrees. Select and use the optimal angle according to the surrounding conditions.

Effect of the Invention The present invention, as is apparent from the above embodiment, provided a reflector at an oblique angle to the road surface above the ultrasonic transceiver,
By changing the reflection direction of the reflected wave from the road surface by the reflector, there is an advantage that occurrence of multiple reflection between the road surface and the upper structure can be prevented. Therefore, there is an effect that the vehicle can be reliably detected without malfunction even in an environment where a structure exists above the ultrasonic transmitter / receiver, such as in a tunnel or under an elevated road.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram of an ultrasonic vehicle detecting device according to an embodiment of the present invention, FIG. 2 is a schematic block diagram of a conventional ultrasonic vehicle detecting device, and FIG. 3 is a conventional ultrasonic vehicle detecting device. 5 is a timing chart of transmission and reception of ultrasonic waves in the device. DESCRIPTION OF SYMBOLS 1 ... Ultrasonic transmitter / receiver, 2 ... Connection cable, 3 ... Vehicle detection unit, 4 ... Ultrasonic transmission unit, 5 ... Matching transformer, 6 ... Reception amplification unit, 7 ... Level detection unit, 8 …… Signal processing unit, 9 …… Ultrasonic emission wave, 10 …… Ultrasonic reflected wave,
11 ... vehicle, 12 ... road surface, 13 ... reflection plate, 14 ... road surface reflection plate reflected by the reflection plate, 15 ... superstructure, 21 ...
... launch wave, 22 ... vehicle reflected wave reception gate, 23 ... road surface reflected wave, 24 ... vehicle reflected wave.

Claims (1)

(57) [Claims] 1. An ultrasonic vehicle detection device comprising a reflector provided at an upper portion of an ultrasonic transmitter / receiver at an oblique angle with respect to a road surface.