JPH06131588A - Traffic jam detector for automobile - Google Patents

Abstract

PURPOSE:To objectively and accurately detect the existence of traffic jam of automobiles. CONSTITUTION:In each passage of a vehicle 3, the vehicle 3 generates light 7A from a laser emitter 20 to a light receiver 32 on a light reflecting marker 5. The light 7A is converted into a current by the light receiver 32 and accumulated as voltage corresponding to the integrated light receiving value by a voltage holder 34. In each passage of a vehicle, a polarizing face angle changing device 36 projects light 7B obtained by changing the angle of the polarizing face of the light 7A in accordance with the voltage to the vehicle 3. A laser receiver 24 on the vehicle 3 finds out the angle of the polarizing face of the light 7B and then a controller 26 finds out an angular difference between both light 7A, 7B. Since the angular difference expresses the number of vehicles passing the marker 5, the existence of the traffic jam on the succeeding road can be judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a traffic jam condition of an automobile, and more particularly, to an apparatus for detecting a traffic jam condition of an automobile using a light reflection marker previously installed on a road.

[0002]

2. Description of the Related Art Up to now, in order for a driver to know the traffic condition of a road on which he is currently traveling while he is driving a car, he has relied on traffic information displayed on a display plate installed on the road. This traffic congestion information is obtained by the control room empirically determining the vehicle passage amount based on a vehicle passage signal generated by an ultrasonic sensor attached to a road in advance every time the vehicle passes.

As a device for detecting traffic congestion, Japanese Patent Laid-Open No. 129797/1990 discloses a device for determining the presence or absence of traffic congestion based on the alternating repetition frequency of slow acceleration and slow deceleration of a vehicle. Furthermore, JP-A-2-144700
The publication discloses a device for determining the presence or absence of traffic jam on a curved uphill road based on a correlation coefficient obtained from an accelerator operation speed and a steering speed.

[0004]

However, since the judgment of the vehicle passage amount by the control room is empirical, the traffic congestion information is not always accurate and is required for the line between the ultrasonic sensor, the control room and the display board. The cost is enormous, and the structure is inevitably complicated.

In addition, the traffic congestion determination devices described in the above two publications are for determining the presence or absence of traffic congestion based only on the traveling state of the own vehicle. Therefore, for example, in the device described in Japanese Patent Laid-Open No. 2-129797, even if the alternating repetition frequency of slow acceleration and slow deceleration becomes equal to or more than a predetermined value, it is caused by congestion. It is not possible to determine whether it is due to a malfunction of the own vehicle or other factors,
It is not always possible to accurately determine whether there is congestion.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a traffic jam detecting device for an automobile, which can accurately determine the presence or absence of traffic jam and is relatively low in cost.

[0007]

In order to achieve this object, the vehicle traffic jam detecting device according to the present invention uses a light reflection marker which is provided in advance on a traveling road. This light reflection marker includes a light receiving means for receiving incident light, a polarization plane angle changing means for changing the angle of the polarization plane of light according to the magnitude of an external signal, and an incident light received by the light receiving means within a predetermined time. It is provided with a signal amount changing means for changing the magnitude of the external signal according to the integrated amount of received light, and a light emitting means for emitting light whose polarization plane angle is changed by the polarization plane angle changing means.

On the other hand, the vehicle receives the light from the light source which emits the linearly polarized light as the incident light to the light reflection marker and the light from the light emitting means of the light reflection marker, and determines the polarization plane angle of the light. The polarization plane angle detection means for detecting and the angle difference between the polarization plane angle of the linearly polarized light emitted by the light source and the polarization plane angle of the light detected by the polarization plane angle detection means are calculated, and the angle difference is calculated according to the angle difference. And a plane-of-polarization angle difference calculating means for obtaining a vehicle passing amount within a predetermined time.

In a preferred embodiment of the present invention, the polarization plane angle changing means is a magneto-optical element arranged so that incident light passes through in the axial direction, and a magnetic field applying means for applying a predetermined magnetic field to the magneto-optical element. With. In this case, the strength of the magnetic field applied to the magneto-optical element corresponds to the above-mentioned external signal. In a preferred embodiment of the present invention, the traffic jam detection device further includes a photoelectric element that generates a current according to the amount of received light, and a capacitor that stores the current generated by the photoelectric element. In this embodiment, the received light integrated amount of the incident light received by the light receiving means is accumulated as a voltage in the capacitor, and the voltage is applied to the magnetic field applying means, so that a magnetic field having a magnitude corresponding to the voltage is generated. , The magnetic field is applied to the magneto-optical element.

In the preferred embodiment of the present invention, a discharge circuit is connected to the capacitor. In a preferred embodiment of the present invention, a timer is connected between the capacitor and the discharge circuit, and the timer connects the capacitor and the discharge circuit at regular intervals.

[0011]

The vehicle passing through the light reflecting marker irradiates the light reflecting marker installed on the side of the road with linearly polarized light,
Go through. The light receiving means of the light reflection marker receives the light emitted by the vehicle passing through the light reflection marker, integrates the received light amount, and stores the integrated value.

The signal amount changing means of the light reflection marker sends a signal corresponding to the integrated value of the received light amount to the polarization plane angle changing means, and the polarization plane angle changing means is incident on the light reflection marker according to the magnitude of the signal. The angle of the plane of polarization of the incident light is changed. The light whose polarization plane angle is changed in this manner is sent from the light emitting means to the traveling vehicle, and the polarization plane angle detection means of the traveling vehicle receives the light. The polarization plane angle detection means of the vehicle is
Further, the angle difference between the polarization plane angle of the received light and the polarization plane angle of the light initially emitted by the vehicle is calculated.

The more vehicles pass through the light reflection marker,
The integrated value of the amount of light received by the light reflection marker is large, and therefore the change in the angle of the plane of polarization of light is also large. That is,
The angle difference of the polarization plane of light corresponds to the number of vehicles that have passed through the light reflection marker before the vehicle receives the light from the light reflection marker, and the larger the angle difference of the polarization plane is, the longer the predetermined time (for example, It is shown that many vehicles have passed the light reflection marker earlier than the own vehicle within 5 minutes. Therefore, from the magnitude of the angle difference, it can be determined whether or not the road is congested.

The polarization plane angle changing means includes a magneto-optical element,
The magneto-optical element can be composed of a magnetic field applying means for applying a magnetic field. Since the angle of the plane of polarization of light can be changed according to the strength of the magnetic field, by controlling the strength of the magnetic field, the angle of the plane of polarization of light can be changed according to the light reception integrated amount of the light receiving means. The traffic jam detecting device may further include a photoelectric element that generates a current according to the amount of received light, and a capacitor that accumulates the current generated by the photoelectric element. The photoelectric element generates a current according to the received light integrated amount of the incident light received by the light receiving means,
By accumulating the current in the capacitor, a voltage according to the amount of the current can be obtained. When this voltage is applied to the magnetic field applying means, a magnetic field having a magnitude corresponding to the voltage is generated. If the magnetic field is applied to the magneto-optical element, the angle of the plane of polarization of the light can be changed according to the integrated amount of received light.

A discharge circuit can be connected to the capacitor. By connecting the discharge circuit, it is possible to prevent excessive accumulation of current in the capacitor, and to prevent damage to the capacitor and, consequently, malfunction of the traffic jam detection device. Furthermore, by connecting a timer between the capacitor and the discharging circuit and discharging the capacitor at regular intervals, it is possible to delete past data regarding the number of passing vehicles that is accumulated as the amount of current. That is, the data can be updated at regular time intervals, and erroneous determination based on old data can be prevented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the basic operation of a light reflection marker used in an automobile traffic jam detecting apparatus according to the present invention will be described with reference to FIGS. As shown in FIG. 1, a vehicle 3 running on a road 1 irradiates a light-reflecting marker 5 installed on the side of the road with linearly polarized light 7A. After receiving the light 7A, the light reflection marker 5 changes the angle of the polarization plane of the light 7A and sends it back to the vehicle 3 as the light 7B.

The vehicle 3 has a polarization plane angle difference calculation device for calculating the difference in angle of polarization plane between the emitted light and the received light. After receiving the light 7B, the light 7A and the light 7B are received. The angle difference of the plane of polarization between and is calculated. If the angle of the plane of polarization of the light 7B is changed according to the information to be transmitted to the driver of the vehicle 3, the angle difference between the light 7A and the light 7B represents that information, so that the plane of polarization of the light is changed. It is possible to transmit necessary information to the driver by appropriately changing the angle.

FIG. 2 is a schematic view of the light reflection marker 5. The light reflection marker 5 is a cylindrical magneto-optical element 9 made of a translucent magneto-optical material, and a reflecting mirror 1 arranged perpendicularly to the axial direction of the magneto-optical element 9 and adjacent to the magneto-optical element 9.
1 and a coil 13 wound around the outer circumference of the magneto-optical element 9. By passing a current through the coil 13, a magnetic field having a magnitude corresponding to the current is generated inside the magneto-optical element 9.

In the magneto-optical element 9, the light 7A emitted from the vehicle 3 is parallel to the axial direction of the magneto-optical element 9.
It is arranged to be incident on. The light 7A passes through the inside of the magneto-optical element 9 and is vertically incident on the reflecting mirror 11,
After being reflected perpendicularly and passing through the inside of the magneto-optical element 9 again, it travels toward the vehicle 3 as light 7B. When the lights 7A and 7B pass inside the magneto-optical element 9, that is, in the magnetic field, the polarization plane of the light rotates around the traveling direction of the light, and the angle of the polarization plane of the light changes. The angle of the plane of polarization of this light is the distance that the light passes through the magnetic field (that is, twice the length L in the axial direction of the magneto-optical element) and the strength of the magnetic field (this magnetic field strength is the number of turns of the coil 13). And proportional to the current I flowing in the coil 13) are used as parameters.

FIG. 3 shows an embodiment of an automobile traffic jam detecting apparatus according to the present invention. The vehicle 3 running on the road 1 is equipped with the traffic jam detection device A, and the light reflection marker 5 installed beside the road 1 has the polarization plane angle changing device B built therein. The traffic jam detection device A includes a laser light emitter 20 as a light source that emits linearly polarized light 7A, and a light reflection marker 5.
Of the polarization plane angle changing device B, and a laser receiver 2 as polarization plane angle detection means for receiving the light 7B through the polarization filter 22.
4 and a controller 26 as a polarization plane angle difference calculating means for calculating an angle difference between the polarization plane angle of the light 7A emitted by the laser light emitter 20 and the polarization plane angle of the light 7B received by the laser light receiver 24. Consists of. As will be described later, the controller 26 not only calculates the angle difference, but also determines the congestion amount based on the angle difference.

On the other hand, the polarization plane angle changing device B includes a polarizing filter 30 for polarizing the light 7A emitted by the laser light emitter 20 of the traffic jam detecting device A, and the light 7A from the laser light emitter 20 via the polarizing filter 30. A light-receiving device 32 as a light-receiving unit that receives the light and generates a voltage according to the received light integrated amount of the light 7A received within a predetermined time (for example, 5 minutes)
And a voltage holder 34 as a signal amount changing means for holding the voltage generated by the light receiver 32, and the angle of the polarization plane of the light 7A emitted by the laser light emitter 20 of the traffic jam detector A, and further, With respect to the angle of the plane of polarization of the light 7A, the angle of the plane of polarization of the light is changed according to the signal generated by the voltage holder 34 and representing the magnitude of the voltage, and the light 7B in which the angle of the plane of polarization is changed is supplied to the vehicle 3 And a polarization plane angle changing device 36 serving as a light emitting means for changing the polarization plane angle.

FIG. 4 is a schematic view showing a specific example of the polarization plane angle changing device B. Laser emitter 2 of traffic jam detector A
The light 7A emitted by 0 is received by the photodiode 40 via the polarization filter 30. Photodiode 4
0 generates a current according to the amount of received light. The current generated in the photodiode 40 flows into the capacitor 42 and is accumulated in the capacitor 42. Condenser 42
Holds a voltage according to the amount of accumulated current and functions as a voltage holder 34 in the polarization plane angle changing device B. The photodiode 40 and the capacitor 42 are both grounded.

The polarization plane angle changing device B has the same unit as the unit including the magneto-optical element 9, the coil 13 and the reflecting mirror 11 shown in FIG.
One end of the coil 13 as the magnetic field applying means is connected to the condenser 42. The other end of the coil 13 is grounded. Further, the capacitor 42 is connected to the resistor 46 via the timer 44. The timer 44 connects the capacitor 42 and the resistor 46 each time a predetermined time has elapsed, and the capacitor 4 is connected via the resistor 46.
2 discharge is performed. The other end of the resistor 46 is grounded.

The traffic jam detecting apparatus according to this embodiment having the above structure operates as follows. The vehicle 3 includes the laser light emitter 20 to the photodiode 4 of the polarization plane angle changing device B.
Light 7A is emitted toward 0 and the reflecting mirror 11. The photodiode 40 converts the light 7A into a current and sends the current to the capacitor 42. The condenser 42 stores a current amount according to the number of vehicles 3 that have passed through the light reflection marker 5 and holds a voltage having a magnitude according to the current amount.

Since the coil 13 is connected to the condenser 42, a current flows through the coil 13 according to the magnitude of the voltage held by the condenser 42, and the magneto-optical element 9
A magnetic field having a magnitude corresponding to the current is formed in the. The light 7A that has entered the magneto-optical element 9 is reflected by the reflecting mirror 11 and returns to the vehicle 3 as the light 7B until the angle of the polarization plane changes according to the magnetic field strength formed inside the magneto-optical element 9. Can be changed.

The laser receiver 24 of the traffic jam detector A which has received the light 7B whose polarization plane angle has changed reads the angle of the polarization plane of the light 7B and sends a signal representing the angle of the polarization plane of the light 7B to the controller 26. send. The controller 26 calculates the angle difference between the polarization planes of the light 7A and the light 7B based on this signal. As is clear from the above description, the magnitude of the magnetic field formed in the magneto-optical element 9 depends on the light reflection marker 5.
Since it corresponds to the number of vehicles that have passed through, light 7A and light 7
The angle difference of the plane of polarization from B corresponds directly to the number of vehicles.

The controller 26, as shown in FIG.
A map representing the correlation between the angle difference between the polarization planes and the degree of traffic congestion is stored. After calculating the angle difference between the polarization planes of the light 7A and the light 7B, the traffic congestion amount is determined based on this map. . The determined congestion amount is notified to the driver via an appropriate display means (not shown). The current stored in the capacitor 42 is discharged by the timer 44 through the resistor 46 every time a fixed time elapses. This prevents old data from being stored in the condenser 42 forever,
It is possible to always judge whether there is congestion or not by using new data.

The present invention is not limited to the scope of the above embodiments, but various modifications can be made. For example, in the above embodiment, the reflecting mirror 11 is used as the light emitting means of the light reflecting marker 5, but other light emitting means can be used instead of the reflecting mirror 11. Instead of the unit of the magneto-optical element 9, the coil 13 and the reflecting mirror 11 shown in FIG.
An appropriate device capable of changing the angle of the plane of polarization of light according to the voltage is connected to the condenser 42, and further,
A light source is connected to the device. With such a configuration, light whose angle of polarization plane is changed according to the voltage held by the condenser 42 is emitted from the light source.

[0029]

The vehicle traffic jam detecting device according to the present invention comprises:
By using the light reflection marker, the presence or absence of traffic congestion is determined in relation to the number of vehicles that have passed through before the host vehicle, so it is more objective than the conventional device that determines only from the running state of the host vehicle. And it becomes possible to make an accurate determination. Further, compared with the case where the control room makes a determination based on the signal from the ultrasonic sensor, the presence or absence of traffic congestion can be determined with an inexpensive and simple device.

[Brief description of drawings]

FIG. 1 is a schematic view showing an outline of an operating state of a vehicle traffic jam detection device according to the present invention.

FIG. 2 is a schematic diagram showing a basic concept of a light reflection marker used in the present invention.

FIG. 3 is a schematic view of an embodiment of an automobile traffic jam detecting device according to the present invention.

FIG. 4 is a schematic diagram of a polarization plane angle changing device B of FIG.

FIG. 5 is a graph showing an example of a map showing the correlation between the angle difference of the polarization plane of light and the amount of traffic jam.

[Explanation of Codes] 1 Road 3 Vehicle 5 Light Reflection Marker 7A Incident Light 7B Reflected Light 9 Magneto Optical Element 11 Reflector 13 Coil A Congestion Detection Device 20 Light Emitting Laser 22 Polarization Filter 24 Laser Receiver 26 Controller B Polarization Plane Angle Changer 30 Polarization Filter 32 Light Receiver 34 Voltage Holder 36 Polarization Plane Rotator 40 Photodiode 42 Condenser 44 Timer 46 Resistor

Claims (5)

[Claims] 1. A traffic jam detection device for a vehicle, which allows a traveling vehicle to detect the amount of traffic jam on a road using a light reflection marker provided on the road, wherein the light reflection marker detects incident light. The light receiving means for receiving light, the polarization plane angle changing means for changing the angle of the polarization plane of light according to the magnitude of the external signal, and the external device according to the received light integrated amount of the incident light received by the light receiving means within a predetermined time. The traveling vehicle is provided with a signal amount changing means for changing the magnitude of the signal and a light emitting means for emitting light whose polarization plane angle is changed by the polarization plane angle changing means. A light source that emits light as incident light to a light reflection marker, a light plane from the light emission means of the light reflection marker, a polarization plane angle detection means that detects a polarization plane angle of the light, and a linearly polarized light Polarization plane angle and the polarization plane angle detection A vehicle traffic congestion detection, comprising: a polarization plane angle difference calculation means for calculating an angle difference from the polarization plane angle of the light detected by the means, and for obtaining the vehicle passage amount within the predetermined time according to the angle difference. apparatus. 2. The magneto-optical element, wherein the polarization plane angle changing means is arranged so that the incident light passes in the axial direction,
2. The automobile traffic jam detection device according to claim 1, further comprising magnetic field applying means for applying a predetermined magnetic field to the magneto-optical element, wherein the external signal is the intensity of the magnetic field. 3. A capacitor comprising: a photoelectric element that generates a current according to the amount of received light; and a capacitor that stores the current generated by the photoelectric element, wherein the received light integrated amount of the incident light received by the light receiving means is used as a voltage. 3. The vehicle according to claim 2, wherein the voltage is applied to the magnetic field applying means, the voltage is applied to the magnetic field applying means, a magnetic field having a magnitude corresponding to the voltage is generated, and the magnetic field is applied to the magneto-optical element. Traffic jam detector. 4. The automobile traffic jam detection device according to claim 3, wherein a discharge circuit is connected to the capacitor. 5. The automobile according to claim 4, wherein a timer is connected between the capacitor and the discharge circuit, and the capacitor and the discharge circuit are connected at regular intervals. Traffic jam detector.