JPH0464036B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting a vehicle to be measured that allows a vehicle to be measured to be detected from among a plurality of vehicles.

Generally, detection devices for vehicles to be measured are installed on both sides of a test course and used to measure vehicle passing time, passing speed, etc.
As this type of device, a light-shielding device equipped with a phototube is used, which detects a vehicle to be measured when a traveling vehicle interrupts the optical path between the light emitting device and the light receiving device.

By the way, test courses are generally designed so that multiple vehicles can run at the same time, and when multiple vehicles run at the same time, the conventional light-shielding detection device described above cannot distinguish between the vehicle to be measured and other vehicles. During measurements, it was necessary to prohibit other vehicles from driving, which resulted in the problem of inefficient use of the test course.

The present invention has been made to solve the above-mentioned problems, and includes a first polarized light beam in front of a light projector and a light receiver for detecting the passage of a specific vehicle to be measured traveling on a vehicle travel path. and a second polarizing member are arranged, and an optical rotation member that makes the polarization axis of the light that has passed through the first polarizing member match the polarizing axis of the second polarizing member is installed on the vehicle to be measured, and a connection between the projector and the light receiver is made. Only when the vehicle to be measured passes, the light that has passed through the first polarizing member is made to enter the light receiver via the second polarizing member by the optical rotation member, thereby preventing the plurality of vehicles traveling on the above-mentioned travel path at the same time. By making it possible to detect only the passage of the measured vehicle from among the measured vehicles, it is possible to improve the usage efficiency of the vehicle traffic route by allowing other vehicles to run while the measured vehicle is being measured. The purpose is to obtain a detection method.

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 are diagrams for explaining a method for detecting a vehicle to be measured according to an embodiment of the present invention,
FIG. 1 shows a schematic configuration of a detection device used in this detection method, and FIG. 2 shows a configuration of a vehicle to be measured. In the figure, reference numeral 1 denotes a vehicle running path that is long in the longitudinal direction (perpendicular to the plane of the first drawing), and on the left side of the vehicle running path 1, a floodlight mounting frame 2 is fixed with anchor bolts 2a, and is attached to the upper end of the mounting frame 2. A laser projector 4 is housed and held in the projector case 3. A power unit 5 is connected to the laser projector 4, and the power unit 5 is further connected to a power source by a lead wire 5a.

Further, a light receiver mounting frame 6 is fixed to the right side of the vehicle running path 1, and a laser receiver 8 is housed and held in a light receiver case 7 attached to the upper end of the frame 6, and the light receiver 8 is connected to a lead wire 8a. The laser receiver 8 faces the laser projector 4, and the optical path 9 between the laser projector and receivers 4 and 8 is horizontal and parallel to the vehicle travel path 1. It is perpendicular to the direction of travel.

A first mounting bracket 10a is attached to the vehicle traveling path 1 side of the projector case 3, and a first polarizing member 10 is housed and held in the bracket 10a at right angles to the optical path 9. The polarization axis of the member 10 is in the vertical direction. Further, a second mounting bracket 11a is attached to the vehicle traveling path 1 side of the light receiver case 7.
A second polarizing member 11 is housed and held in 1a at right angles to the optical path 9, and the polarization axis of the second polarizing member 11 is in the horizontal direction, so that the light transmitted through the first polarizing member 10 is It is designed to be opaque.

Further, at the center of the front bumper 12a of the vehicle 12 to be measured, there is a base 1 of a T-shaped mounting bracket 13.
3a is fixed with bolts using the license plate mounting hole, and the holding portion 13b of the bracket 13 projects forward. Two transparent acrylic plates 14 are bolted and fixed to the holding part 13b, and an optical rotation member 15 made of a 1/2 wavelength plate is installed between the two acrylic plates 14 for the optical path 9.
The optical rotation member 15 is held at the same height as the polarization axis of the light transmitted through the first polarization member 10.
It is rotated by 90° to make it horizontal and coincide with the polarization axis of the second polarization member 11.

Next, the functions and effects will be explained using FIGS. 3a to 3c. Here, Fig. 3a shows a case where no vehicle is present between the laser projector and receivers 4 and 8;
2. It is a schematic block diagram for demonstrating the effect|action when the other vehicle 20 passes, respectively.

First, when no vehicle is present between the laser projector and the receivers 4 and 8, only the laser beam projected from the laser projector 4, which has a vertical polarization axis, passes through the first polarizing member 10. To Penetrate. The transmitted laser beam then travels along the optical path 9, and when it reaches the second polarizing member 11, it is blocked here because the polarizing axis of the polarizing member 11 is horizontal, so that the laser beam enters the laser receiver 8. No, the photoreceiver 8 remains off.

Next, when the vehicle to be measured 12 passes between the laser projector and receiver 4 and 8, when the optical rotation member 15 of the vehicle to be measured 12 comes to the optical path 9, the vertical A laser beam having a polarization axis has its polarization axis changed by the optical rotation member 15.
It is rotated by 90 degrees and becomes horizontal, and in this state, when it reaches the second polarizing member 11, it is transmitted through this and enters the laser receiver 8, which turns on and sends a detection signal to the measurement circuit. It will be output.
Note that the acrylic plates on both sides of the optical rotation member 15 are transparent and do not affect the polarization axis of the laser beam.

Further, when another vehicle 20 that does not have the optical rotation member 15 passes between the laser projector and light receiver 4, 8, the laser beam transmitted through the first polarizing member 10 is blocked by the other vehicle 20, and the laser beam is blocked by the other vehicle 20. The light does not enter the light receiver 8, and the light receiver 8 remains off.

In this embodiment, the optical rotation member 15 is attached to the vehicle to be measured 12, and the polarization axis of the laser beam transmitted through the first polarization member 10 is set to the second polarization member 11.
Since the polarization axis is made to coincide with the polarization axis of the vehicle, a specific vehicle can be detected even when other vehicles are traveling on the vehicle travel path 1.

Therefore, by providing the detection device used in the above embodiment at the measurement start position and measurement end position of the test course, it is possible to measure the vehicle speed, required passing time, etc. of the vehicle to be measured.

As described above, according to the method for detecting a vehicle to be measured according to the present invention, the first polarizing member and the second polarizing member are provided in front of the projector and the light receiver, respectively, for detecting the passage of the vehicle to be measured traveling on the vehicle travel path. A polarizing member is disposed, and an optical rotation member that makes the polarization axis of the light that has passed through the first polarizing member match the polarizing axis of the second polarizing member is installed on the vehicle to be measured, and a light projector and a light receiver are installed from among the plurality of vehicles. Only when the vehicle to be measured passes through the vehicle, the light that has passed through the first polarizing member is incident on the light receiver via the second polarizing member by the optical rotation member. Since it is possible to detect only the passing of the measured vehicle from within the vehicle, it is possible to detect a specific vehicle even when other vehicles are traveling on the vehicle travel path, and as a result, the usage efficiency of the vehicle travel path can be improved. There are effects that can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a front view of the projector, light receiver, and polarizing member of a device used in a method for detecting a vehicle to be measured according to an embodiment of the present invention, and FIG. 2a is a side view of the vehicle to be measured. 3b is a perspective view of the optically rotating member portion, and FIGS. 3a to 3c are schematic configuration diagrams for explaining the operation thereof. DESCRIPTION OF SYMBOLS 1... Vehicle running path, 4... Light projector, 8... Light receiver, 10... First polarizing member, 11... Second polarizing member, 12... Vehicle to be measured, 15... Optical rotation member.

Claims (1)

[Claims] 1. A vehicle running path that detects only the passing of a specific vehicle while a plurality of vehicles are simultaneously traveling on a vehicle running path that has a light projector and a light receiver facing each other on both sides. A method for detecting a measurement vehicle, which includes arranging a first polarizing member in front of the projector near the projector on a line connecting the projector and the receiver;
A second polarizing member having a polarization axis different from the first polarizing member and making the light passing through the first polarizing member opaque is located in front of the light receiver on the line connecting the light emitter and the light receiver.
A polarizing member was arranged, and an optical rotation member was installed on the vehicle to be measured to match the polarization axis of the light that passed through the first polarizing member with the polarizing axis of the second polarizing member, and the optical rotation member was installed between the light projector and the light receiver. Only when a vehicle to be measured passes among a plurality of vehicles traveling simultaneously on the vehicle running path, the optical rotation member
A method for detecting a vehicle to be measured, characterized in that light that has passed through a polarizing member is incident on a light receiver via a second polarizing member, and only passage of the vehicle to be measured is detected.