JPH10288666A - Vehicle identification device and vehicle distance measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To identify a front vehicle and an opposing vehicle and, for example, road incidental facilities. SOLUTION: A light absorption zone 12 for absorbing light and light reflection zones 13a and 13b with a recursive reflection property are provided at the rear part of a front vehicle 11. A laser device 101 is mounted in the front of a rear vehicle 15. Then, laser beams 101c are directed from the laser device 101 toward the rear part of the front vehicle 11 for scanning and applying beams horizontally by a mechanical means. When the laser device 101 obtains a proper light reflection pattern that is constituted of the light absorption zone 12 and the light reflection zones 13a and 13b for the scanning, it is judged that a vehicle exists at the front. On the other hand, when no light reflection pattern is detected, it is judged that no vehicle exists at the front.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle identification device and an inter-vehicle distance measurement device for an automobile, and more particularly to the device.
The present invention relates to a vehicle identification device and an inter-vehicle distance measuring device that do not malfunction due to light reflected from a light reflecting object other than a vehicle.

[0002]

2. Description of the Related Art With the deterioration of road conditions in recent years, the number of automobile traffic accidents has been increasing. On the other hand, officials such as the National Police Agency have instructed to keep a proper distance between vehicles, but most of the drivers do not follow the guidance. In particular, on a highway or the like, since vehicles are moving at high speed, the driver
It is difficult to accurately determine the distance between the vehicle and the vehicle ahead.

To cope with this problem, various inter-vehicle distance control systems such as an inter-vehicle distance display device and a collision warning device have been devised. These systems mainly include means for emitting and receiving a laser or the like (hereinafter, abbreviated as emission light receiving means) at the front of a vehicle behind (hereinafter, abbreviated as a vehicle behind) which is an observation main body. Light is emitted from the light receiving means toward a vehicle ahead (hereinafter, abbreviated as a forward vehicle) to be observed. In these systems, the reflected light is reflected from the vehicle ahead and the reflected light is received, and the inter-vehicle distance is calculated based on the time required from the emission of the light to the reception of the light. Based on these, these systems display the calculated inter-vehicle distance, or sound a warning sound based on the calculated inter-vehicle distance to inform the driver of the degree of danger, and This is to keep the distance between vehicles.

[0004]

However, in the above-mentioned conventional inter-vehicle distance control system, the outgoing light receiving means is generally fixed in a light emitting direction with respect to the direction of the rear vehicle. In addition, all reflected light (or direct light such as direct sunlight) is accepted. For this reason, the conventional inter-vehicle distance control system
Particularly, on a curved road, the forward vehicle may be out of the irradiation range of the emission light receiving means. Therefore,
The outgoing light-receiving means of the conventional system malfunctions by detecting not only the reflected light from the vehicle in front, which is the target to be observed, but also the reflected light from road-related facilities such as oncoming vehicles, guardrails, signs, and signboards. There is a problem that.
This poses another danger that, for example, if the system issues a sudden braking command in response to an oncoming vehicle, the vehicle may be hit by a following vehicle.

To cope with this, as a conventional technology,
There is a collision warning device described in JP-A-62-130500. The invention described in this publication uses electromagnetic waves, and is based on the following distance calculated from the reflected electromagnetic waves, the own vehicle speed, and the like.
It is an invention that determines whether an object that reflects an electromagnetic wave is dynamic or static and determines whether to issue an alarm. Thus, in the invention described in the above publication, on a curved road, it is determined whether the object that has reflected the electromagnetic wave is a traveling vehicle or a road incidental facility (reflector or the like).

[0006] However, the invention described in the above publication is only a process at the final stage of whether or not to issue an alarm, and is based on a system that observes road-related facilities such as reflectors on a curved road. The problem has not been solved fundamentally. Further, while the vehicle is traveling on such a curved road, the inter-vehicle distance between the front vehicle and the rear vehicle cannot be measured.

[0007] Therefore, an object of the present invention is to be able to distinguish a vehicle ahead from a road-related facility such as an oncoming vehicle or a sign, and
An object of the present invention is to provide a vehicle identification device and an inter-vehicle distance measurement device that do not malfunction except for an object to be observed by continuing observation on a curved road by following a temporal change of a preceding vehicle.

[0008]

According to a first aspect of the present invention, the presence of the preceding vehicle is detected by reflecting the light emitted from the following vehicle by the preceding vehicle and returning to the following vehicle. A vehicle identification device, wherein a preceding vehicle is:
A retroreflecting means for reflecting the incident light in the incident direction; and a light absorbing means for absorbing the light and having no reflection or having a lower reflectance than the retroreflecting means. The absorbing means is provided at a rear part of the front vehicle by a specific arrangement structure, the rear vehicle is provided at a front part of the rear vehicle, and includes light emitting and receiving means for emitting and receiving light, After emitting light while scanning in the horizontal direction toward a specific arrangement structure, by detecting a unique light reflection pattern corresponding to the specific arrangement structure,
The present invention is characterized in that an object that reflects light ahead is identified as a vehicle.

As described above, the first invention is a means having retroreflection for reflecting incident light in the incident direction,
A light absorbing means that absorbs light and has no reflection or has a lower reflectance than retroreflective means is provided at the rear of the vehicle in a specific arrangement structure. Thereby, at the rear of the vehicle,
By irradiating light horizontally from the front of the rear vehicle, a unique light reflection pattern corresponding to the specific arrangement can be generated. Therefore, by observing this unique light reflection pattern, it is possible to determine whether or not the object that reflects light is a vehicle. Therefore, it is possible to eliminate malfunctions that have occurred in road-related facilities such as oncoming vehicles, guardrails, signs, and signboards, as in the conventional device.

According to a second aspect of the present invention, when the light emitting and receiving means in the first aspect detects a unique light reflection pattern partially missing, the direction of the light emitting and receiving means follows the missing direction. It is characterized by further comprising an angle control means for changing.

As described above, the second aspect of the present invention relates to the case where the pattern of the reflected light detected by the light emitting / receiving means in the first aspect is partially missing and is not a complete unique light reflection pattern. The angle control means determines in which direction the pattern is missing, and changes the direction of the light emitting / receiving means in that direction. As a result, it is possible to follow the preceding vehicle so as to always detect a unique light reflection pattern and observe the temporal change in the traveling direction of the preceding vehicle on a curved road or the like. It is possible to prevent the malfunction that has been performed.

A third invention is the reflection film according to the first and second inventions, wherein the retroreflection means is arranged in an array of spherical lenses having a light reflection layer formed on the side opposite to the side on which light is incident. It is characterized by being.

As described above, in the third invention, the retroreflection means in the first and second inventions is a reflection film in which spherical lenses each having a reflection layer are arranged in an array. The effects of the invention are the same as the effects of the first and second inventions.

A fourth invention is characterized in that, in the first and second inventions, the retroreflection means is a reflection film in which corner cubes are formed in an array.

As described above, in the fourth invention, the retroreflective means in the first and second inventions is a reflection film in which corner cubes are formed in an array. The effects of the invention are the same as the effects of the first and second inventions.

A fifth invention is characterized in that, in the first and second inventions, the light in the light emitting / receiving means is a laser.

As described above, in the fifth invention, the light emitting and receiving means in the first and second inventions is means for emitting and receiving a laser. The effects of the invention are the same as the effects of the first and second inventions.

According to a sixth aspect of the present invention, an inter-vehicle distance measuring device for measuring the distance between the preceding vehicle and the rear vehicle by reflecting the light emitted from the rear vehicle at the front vehicle and returning to the rear vehicle. In the preceding vehicle, a retroreflecting means for reflecting the incident light in the incident direction, and a light absorbing means that absorbs the light and has no reflection, or a light absorbing means having a lower reflectance than the retroreflecting means. The light absorbing means and the retroreflecting means are provided at the rear of the front vehicle by an arrangement having both ends as the retroreflecting means, and the rear vehicle is provided at the front of the rear vehicle, and emits and receives light. A light emitting / receiving means for outputting a reference signal corresponding to each of the emission and light receiving, and a distance calculating means for converting a time difference between the signals into a distance based on the reference signal output by the light emitting / receiving means. Distance calculating means from the angle of the retroreflector forms of each time difference and the ends at both ends of the light emitting receiving means outputs, characterized by measuring the distance to the preceding vehicle and the following vehicle.

As described above, the sixth aspect of the present invention provides a means having retroreflection for reflecting incident light in an incident direction;
A light absorbing means that absorbs light and has no reflection or has a lower reflectance than the retroreflecting means is provided at the rear of the vehicle in an arbitrary arrangement structure in which both ends are retroreflecting means. Then, light is emitted toward the retroreflecting means, and the time until the reflected light is received is measured for each of the two ends. This makes it possible to measure the distance between the preceding vehicle and the following vehicle from the time and the angle formed by the retroreflecting means at both ends.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment of Vehicle Identification Apparatus) FIG. 1 is a perspective view of a rear part of a vehicle traveling forward showing an example of installation of light reflection means and light absorption means of a vehicle identification apparatus according to one embodiment of the present invention. In FIG. 1, an example of installation of the light reflecting means and the light absorbing means of the vehicle identification device according to one embodiment of the present invention includes a light absorbing band 12 and a light reflecting band 13a, 1
3b.

First, the light absorption band 12, the light reflection band 13a, 1
3b will be described. The light absorption band 12 is formed by applying a paint or the like having a low light reflectance (in the vehicle identification device according to the present embodiment, reflection is performed only to such an extent that reflection from the light reflection bands 13a and 13b is not recognized). . The light reflection bands 13a and 13b are formed by attaching members having retroreflection properties. The retroreflective property refers to a property of reflection such that reflected light selectively returns in a direction substantially along the optical path of incident light over a wide incident angle.

Here, an embodiment of a member having a retroreflective property which can be used as the light reflection bands 13a and 13b will be described with reference to FIG. The light reflecting means shown in FIG. 2A is a spherical lens type. The spherical lens type has a structure in which a plurality of spherical lenses 21 are arranged in a reflective film 22 at high density. The spherical lens 21 has a diameter of about 5
It has a transparent sphere of 0 to 100 μm. In FIG. 2, the lower hemispherical surface (where light is not directly incident) has a reflective layer 23 that reflects light. The reflective layer 23 can be formed to have an arbitrary size (area) depending on the purpose of use (that is, how much directivity is given). I have it).

The incident light 24 entering the spherical lens 21 first enters the spherical lens 21 and is refracted at the same time as the incident angle. The refracted light travels in the spherical lens 21 until it reaches the reflective layer 23, and is reflected by the reflective layer 23. The light reflected by the reflection layer 23 passes through the spherical lens 21 again into the spherical lens 2.
Continue until you reach surface 1. Then, when light is emitted from the spherical lens 21, refraction is performed again.
The reflected light 25 is parallel to the light 4 and returns in the direction of the incident light 24. That is, it has retroreflectivity.

On the other hand, the light reflecting means shown in FIG.
It is a corner cube type. The corner cube type is one in which the corner cubes 26 are arranged in an array and formed into a film. The corner cube 26 refers to a triangular cone-shaped prism or reflecting mirror having three surfaces that intersect at right angles to each other.
Light incident on the bottom surface (other than the three surfaces) is
After being reflected each time, the light is emitted from the bottom surface and returned to the original direction. Therefore, this corner cube type also
Like the spherical lens type shown in FIG. 2A, it has a retroreflectivity for reflecting reflected light parallel to incident light.

The light reflection bands 13a and 13b and the light absorption band 12 as described above are provided as shown in FIG. That is, the light reflection bands 13a and 13b are provided at the left and right corners at the rear of the front vehicle 11, respectively, and the light absorption band 12 is
It is provided between the light reflection bands 13a and 13b. Thereby, when light crosses the rear part of the front vehicle 11 in the horizontal direction, there is first reflected light by the light reflection band 13a (or 13b), and then no reflected light by absorption by the light absorption band 12.
Further, a unique light reflection pattern in which light is reflected by the light reflection band 13b (or 13a) (hereinafter, referred to as "reflection-absorption-reflection") can be obtained. The light reflection pattern installed in the present embodiment and the like is an example, and other light reflection patterns can be used as long as they can be identified as unique light reflection patterns by the vehicle identification device described in the present embodiment. It may be.

Next, a method for identifying a vehicle traveling ahead having the light reflection bands 13a and 13b and the light absorption band 12 will be described with reference to FIG. FIG. 3 is a top view showing an operating state of the vehicle identification device according to the embodiment of the present invention in a running vehicle. In FIG. 3, a laser device 101 is provided at a front portion of the rear vehicle 15. Note that the laser device 101 includes a laser head 101a that emits a laser beam and a photodetector 101b that receives reflected light (not shown in FIG. 3).

The laser device 101 provided at the front of the rear vehicle 15 emits a laser beam 101c from the laser head 101a to the light reflection band 13a (or 13b) at the left and right corners of the front vehicle 11. This irradiation is performed by mechanical means while scanning in the horizontal direction, that is, in the direction from the light reflection band 13a to the light reflection band 13b (or in the opposite direction) (hereinafter, referred to as horizontal irradiation). Here, only when the photodetector 101b detects the reflected light of the unique light reflection pattern called “reflection-absorption-reflection” for one scan of horizontal irradiation, the vehicle identification device according to the present embodiment is It is determined that a vehicle is present ahead. In addition, the above-mentioned determination is performed by statistically “is likely” by comparing the light reflection pattern with the observation contents before and after, in consideration of a case where a light reflection pattern is accidentally obtained from an object other than the object. However, for one scan of horizontal irradiation, the photodetector 101b
If no light to be reflected is detected, the vehicle identification device according to the present embodiment determines that there is no vehicle in front. In addition, if the photodetector 101b detects reflected light but does not have the specific light reflection pattern described above, or if the amount of reflected light is not recognized as the amount of light reflected from the light reflection bands 13a and 13b, the present embodiment will be described. Such a vehicle identification device determines that the vehicle is a road incidental device such as an oncoming vehicle, a guardrail, or a sign.

As described above, the light reflecting means and the light absorbing means for generating a light reflecting pattern unique to only the vehicle that is to become the preceding vehicle 11 are provided. Thereby, it is possible to determine whether a vehicle is present ahead by horizontally irradiating the laser beam forward and determining whether or not the corresponding reflected light is the specific light reflection pattern. Therefore, it is possible to prevent the occurrence of malfunction due to the reflection from road-related facilities such as oncoming vehicles, guardrails, and signs, which is observed in the conventional system.

(Embodiment of inter-vehicle distance measuring device) As described above, when it is confirmed that a vehicle is present ahead by detecting a unique light reflection pattern, the inter-vehicle distance between the preceding vehicle 11 and the following vehicle 15 is determined. The distance can be measured as follows. Hereinafter, the operation and control of the inter-vehicle distance measurement device configured based on the above-described vehicle identification device will be sequentially described.

FIG. 4 is a block diagram showing the configuration of an inter-vehicle distance measuring apparatus according to one embodiment of the present invention. In FIG. 4, an inter-vehicle distance measuring device according to an embodiment of the present invention includes:
A laser device 101, a laser controller 102, a distance gate generator 103, a light receiving circuit 104, and an oscillator 105
, An AND circuit 106, a distance calculation circuit 107, an angle error detection circuit 108, and a laser head driving mechanism 109. The laser device 101 includes a laser head 101a
And a photodetector 101b. FIG.
5 is a timing chart showing a signal relationship of each part of (G) to (K) in FIG.

First, in order to measure the inter-vehicle distance, the scanning angle of the laser beam is controlled, and the irradiation width of the laser beam is made to coincide with the vehicle width of the preceding vehicle 11 and fixed (hereinafter, referred to as the vehicle width).
The operation will be further described with reference to FIG. In FIG. 6, α is the laser head 101a.
Indicates the leftmost end of the laser beam to be irradiated, and β indicates the rightmost end. θ is an angle between the leftmost end α and the rightmost end β (hereinafter, referred to as a scanning angle). γ is the scan angle θ
(Hereinafter, referred to as a θ center line) and the front plane of the rear vehicle 15 (hereinafter, referred to as an irradiation angle).

As a prerequisite for operating the apparatus according to the present invention, the scan angle θ is set to a wide angle when the apparatus is started up, for example, when the power is turned on. Scan angle θ at the time of this initial setting
Is, for example, the device with respect to a vehicle width 2m, in order to be able accurately measure until the inter-vehicle distance 1m is, 2 × tan ^-1 1 = 90 may be set to [deg].

When the inter-vehicle distance measuring apparatus according to the present embodiment is started up, the positional relationship between the front vehicle 11 and the rear vehicle 15 is as shown in FIG. In this state, the vehicle identification operation, that is, the first horizontal irradiation of the laser beam is performed. As a result of this horizontal irradiation, when a unique light reflection pattern of “reflection-absorption-reflection” shown in FIG. 6B is observed in the light receiving circuit 104 via the photodetector 101b, as described above, the vehicle moves forward. Judge that it exists. As described above, when the presence of the preceding vehicle 11 is determined, the light receiving circuit 104 instructs the angle error detection circuit 108 to control the laser head driving mechanism 109 to fix the laser head 101a toward the leftmost end α side. And instruct the laser controller 102 to irradiate the laser beam after the fixing. Then, the light receiving circuit 104 reflects the reflected light corresponding to the specified laser beam irradiation (that is, the reflected light from the light reflection band 13a).
Observe if there is. Thereafter, the light receiving circuit 104
Further, it instructs the angle error detection circuit 108 to control the laser head driving mechanism 109 to fix the laser head 101a toward the rightmost end β side, and irradiates the laser controller 102 with a laser beam after the fixing. Instructions. Then, the light receiving circuit 104 receives the reflected light (light reflection band 1) in response to the specified laser beam irradiation.
3b) is observed.

As a result of performing the above operation, the light receiving circuit 104
Are the light reflection bands 1 corresponding to the leftmost end α side and the rightmost end β side.
If the reflected light from both 3a and 13b cannot be observed, it is determined that the scanning angle θ is wide. The light receiving circuit 104 controls the laser head driving mechanism 109 for the angle error detection circuit 108 to
An instruction is given to narrow the scan angle θ of a. On the other hand, when the light receiving circuit 104 can observe both of the reflected lights from the light reflection bands 13a and 13b corresponding to the leftmost end α side and the rightmost end β side, the horizontal irradiation is just over the width of the vehicle 11 ahead. It is determined that the scanning angle θ matches, that is, a so-called locked state. In this case, the light receiving circuit 104 does not give any particular instruction to the angle error detection circuit 108. When the light receiving circuit 104 observes only one of the reflected lights from the light reflection bands 13a and 13b corresponding to the leftmost end α side and the rightmost end β side, the relative position between the rear vehicle 15 and the front vehicle 11 is increased. It is determined that there is a displacement (the θ center line does not match the center line of the preceding vehicle 11). Then, the light receiving circuit 104
Gives an instruction to the angle error detection circuit 108 to control the laser head driving mechanism 109 to change the irradiation angle γ of the laser head 101a to correct the direction of horizontal irradiation. After the above control and operation are completed, horizontal irradiation is performed again at the corrected scan angle θ.

The above-described vehicle identification operation and light reflection band confirmation operation are repeatedly performed, and the scanning angle θ and the irradiation angle γ are appropriately controlled, so that the leftmost end α finally comes to the position of the light reflection band 13a. In addition, the rightmost end β is locked at the position of the light reflection band 13b. Accordingly, the laser device 101 always operates not only for the distance between the front vehicle 11 and the rear vehicle 15 but also for the relative deviation of the center line.
It is possible to irradiate the laser beam horizontally within a range that matches the vehicle width of the preceding vehicle 11.

In this locked state, the forward vehicle 1
In the case where the position 1 changes (for example, when the traveling direction of the preceding vehicle 11 changes on a curved road), the unique light reflection that has been observed by scanning within the range of the locked scanning angle θ until now. The pattern will be partially missing. In this case, the vehicle identification device according to the present invention detects the transition of this state in the light reflection band confirmation operation, and moves the laser head 1 in the direction in which the specific light reflection pattern is partially missing.
The operation of correcting the horizontal irradiation direction by changing the irradiation angle γ of 01a is performed. As a result, the vehicle identification device according to the present invention always controls the irradiation angle γ to follow the preceding vehicle 11 even when the preceding vehicle 11 changes over time, which is a problem in the conventional system. It is possible to prevent malfunction on curved roads.

On a curved road, for example, the end of a running road is a Y-shaped road, and the preceding vehicle 11 travels to the left and its own vehicle (that is, the following vehicle 15) travels to the right. And so on. In such a case, the tracking target is the forward vehicle 1 in the traveling direction of the own vehicle.
It is necessary to make it switch appropriately to 1. As a countermeasure, when the irradiation angle γ is changed to a certain degree by the above-described control, the vehicle currently being tracked is appropriately determined as a vehicle to be measured based on information such as the steering state of the steering wheel and the presence or absence of a direction instruction. It may be determined whether or not the irradiation angle γ is reset as necessary.

Next, the inter-vehicle distance measurement performed after the lock control of the scanning angle θ and the irradiation angle γ performed by the above-described vehicle identification operation and the light reflection band confirmation operation will be described with reference to FIG.
This will be described with reference to FIG.

As described above, after the lock control is performed,
Based on the light reflection band confirmation operation, the laser controller 102
An instruction to irradiate a laser beam from the laser head 101a to the laser device 101 is given. At this time, the laser controller 102 outputs an irradiation pulse (G) to the distance gate generator 103 at the same time as giving the above instruction. Here, the distance gate generator 103 is, for example, a bistable multivibrator or the like that changes a stable state by an input trigger pulse. Therefore, outputting the irradiation pulse (G) to the above-described distance gate generator 103 means that the distance gate is opened. The laser head 101a irradiates the laser beam in the leftmost α direction in response to the instruction. At this time, since the device is in a locked state, the laser beam is applied to the light reflection band 1.
Irradiated toward 3a. The irradiated laser beam (hereinafter abbreviated as “irradiation beam”) 101 d is reflected by a light reflection band 13 a provided in the front vehicle 11, and is reflected by the laser beam (hereinafter abbreviated as a “reflected beam”) 10.
1e, and is received by the photodetector 101b. The photodetector 101b includes a reflected beam 101e.
Is received and converted into an electric signal, and then output to the light receiving circuit 104. The light receiving circuit 104 performs processing such as amplification and filtering on the received electric signal, and determines that the electric signal is due to light reflected from the reflection band 13a.
A light receiving pulse (H) is output to the distance gate generator 103. This light receiving pulse (H) is an operation of closing the distance gate. Therefore, a gate pulse (I) as shown in FIG. 5 can be obtained by the above control. Therefore, the width of the gate pulse (I) indicates the time for the laser beam to reciprocate between the laser head 101a and the light reflection band 13a. After the measurement on the light reflection band 13a is completed, the same measurement is performed on the light reflection band 13b to obtain a gate pulse (I) representing the round trip time corresponding to the light reflection band 13b. deep.

The above-mentioned gate pulse (I) is applied when the irradiation of the irradiation beam 101d is completed.
May be generated and a light receiving pulse (H) may be generated at the time when the reception of the reflected beam 101e is completed.

Thereafter, the gate pulse (I) is supplied to the oscillator 1
AND circuit 106 with reference pulse (J) from
And its logical product is taken. As a result, a pulse-converted distance calculation pulse (K) from the laser device 101, that is, the light reflection bands 13a and 13b of the front vehicle 11 from the front end of the rear vehicle 15 is obtained. Then, the distance calculation circuit 107 receives the distance calculation pulse (K), and based on the frequency of the reference pulse (J) of the oscillator 105 and the number of pulses of the distance calculation pulse (K), the light reflection bands 13a and 13b. Find each reflection time.

The inter-vehicle distance from the front vehicle 11 to the rear vehicle 15 can be obtained by obtaining the above-mentioned reflection time. A specific method of calculating the inter-vehicle distance will be described below with reference to FIG.

The respective reflection times obtained in the above-described processing are obtained by setting the reflection time corresponding to the light reflection band 13a to t1 [s].
And the reflection time corresponding to the light reflection band 13b is t2 [s]. The speed of light is C [m / s]. here,
The distance from the laser device 101 to the light reflection band 13a is d1
Assuming that the distance from the laser device 101 to the light reflection band 13b is d2, d1 and d2 can be obtained as follows: d1 = C × t1 / 2 [m] d2 = C × t2 / 2 [m] Therefore, from the d1 and d2 and the scan angle θ [deg], the front vehicle 11 to the rear vehicle 1
The inter-vehicle distance D up to 5 can be obtained as follows: D = (d1 + d2) × cos (θ / 2) / 2 [m].

In the above description of the embodiment, the light irradiation means using a laser has been described.
An LED, a halogen lamp, or the like can be used as long as the above-described unique light reflection pattern can be generated and received.

[Brief description of the drawings]

FIG. 1 is a perspective view of a rear portion of a vehicle traveling forward showing an example of installation of a light reflection unit and a light absorption unit of a vehicle identification device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a structural example of a light reflection band of the vehicle identification device according to the embodiment of the present invention.

FIG. 3 is a top view illustrating an operation state of the vehicle identification device according to the embodiment of the present invention in a running vehicle.

FIG. 4 is a block diagram showing a configuration of an inter-vehicle distance measuring device according to an embodiment of the present invention.

FIG. 5 is a timing chart showing a relationship between pulse signals of respective parts (G) to (K) in FIG.

FIG. 6 is a top view showing an initial operation state of a running vehicle of the vehicle identification device according to the embodiment of the present invention, and a light reflection pattern that can be observed by a light receiving circuit.

FIG. 7 is an enlarged view of a main part of FIG. 3;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Front vehicle 12 ... Light absorption band 13a, 13b ... Light reflection band 15 ... Rear vehicle 21 ... Ball lens 22 ... Reflection film 23 ... Reflection layer 24 ... Incident light 25 ... Reflected light 26 ... Corner cube 101 ... Laser device 101a ... Laser head 101b Photo detectors 101c, 101d, 101e Laser beam 102 Laser controller 103 Distance gate generator 104 Light receiving circuit 105 Oscillator 106 AND circuit 107 Distance calculating circuit 108 Angle error detecting circuit 109 Laser head Drive mechanism

Claims (6)

[Claims] 1. A vehicle identification device for detecting the presence of a preceding vehicle by reflecting light emitted from a following vehicle at a preceding vehicle and returning to the following vehicle, wherein the preceding vehicle is incident. A retroreflecting means for reflecting the reflected light in the incident direction, and a light absorbing means having a low reflectance compared to the retroreflecting means, absorbing the light and having no reflection. The light absorbing means is provided at a rear portion of the front vehicle by a specific arrangement structure, and the rear vehicle is provided at a front portion of the rear vehicle, and includes a light emitting and receiving means for emitting and receiving light. The light receiving unit emits light toward the specific arrangement structure while scanning the light in the horizontal direction, and then detects an inherent light reflection pattern corresponding to the specific arrangement structure, thereby reflecting an object that reflects light in front. But A vehicle identification device for identifying a vehicle. 2. An angle control means for changing the direction of the light emitting / receiving means so as to follow the missing direction when the light emitting / receiving means detects the unique light reflection pattern partially missing. Characterized by further comprising:
The vehicle identification device according to claim 1. 3. The retroreflection means is a reflection film in which spherical lenses having a light reflection layer formed on a side opposite to a side on which light is incident are arranged in an array. 3. The vehicle identification device according to 2. 4. The vehicle identification device according to claim 1, wherein the retroreflection means is a reflection film in which corner cubes are formed in an array. 5. The vehicle identification device according to claim 1, wherein the light in the light emitting / receiving unit is a laser. 6. An inter-vehicle distance measuring device that measures the distance between the front vehicle and the rear vehicle by reflecting light emitted from the rear vehicle at the front vehicle and returning to the rear vehicle. The preceding vehicle includes: a retroreflecting unit that reflects the incident light in the incident direction; and a light absorbing unit that absorbs the light and has no reflection or has a lower reflectance than the retroreflecting unit. The light absorbing means and the retroreflecting means are provided at the rear of the front vehicle by an arrangement in which both ends are the retroreflecting means, and the rear vehicle is provided at the front of the rear vehicle and emits light. And a light emitting and receiving means for receiving and outputting a reference signal corresponding to each of the outgoing and receiving light, and a time difference between the signals based on the reference signal output by the light emitting and receiving means. Distance calculating means, wherein the distance calculating means calculates the time difference at each of the two ends outputted by the light emitting and receiving means and the angle formed by the retroreflecting means at the both ends, and calculates the distance between the front vehicle and the rear part. An inter-vehicle distance measuring device for measuring a distance to a vehicle.