JPH088471Y2 - Optical radar device - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an optical radar device for detecting a dangerous state with respect to another approaching vehicle or obstacle.

[Conventional technology]

Conventionally, a vehicle front monitoring device using a semiconductor laser has been proposed as an optical radar device of this type.

FIG. 11 is a block circuit configuration diagram showing an example of a vehicle front monitoring device that has been conventionally proposed. In the figure, 1 is a semiconductor laser, 2 is a light transmitting lens, 3 is a light receiving lens, and 4 is a light receiving element. The semiconductor laser 1 is driven by a driving device 6 based on a trigger pulse sent from a trigger circuit 5, emits pulsed light (emitted beam light) synchronized with this trigger pulse, and this emitted beam light emits light. The light is converted into a light beam (radiation beam light) having a small spread by 2 and is emitted toward a rear portion or a rear reflector (not shown) of the vehicle 10 traveling in front of it, as shown in FIG. That is, the reflected beam light that is radiated by the vehicle 10 traveling ahead and reflected and returned is condensed by the light receiving lens 3, and the condensed reflected beam light is converted into an electric pulse signal by the light receiving element 4 and is also amplified. 7 is used for amplification, and the signal processing device 8 is used as a received pulse.
It is supposed to lead to.

Since the emitted light beam from the semiconductor laser 1 is synchronized with the trigger pulse sent by the trigger circuit 5, the trigger pulse sent by the trigger circuit 5 is given to the signal processing device 8 so that the trigger pulse and the received pulse are The distance to the vehicle 10 ahead can be calculated from the time difference. Further, the signal processing device 8 obtains the inter-vehicle distance with respect to the forward vehicle 10 from the received pulse and the trigger pulse which are input every moment, and calculates the relative speed with respect to the forward vehicle 10 from the change rate of the inter-vehicle distance. To do. Then, the danger prediction is performed based on the inter-vehicle distance to the preceding vehicle 10, the relative speed, and the own vehicle speed from the vehicle speed sensor 11. If a dangerous state occurs, the buzzer alarm 9 is sounded to notify the driver of the danger.

In such a vehicle front monitoring device, the divergence angle ψ _t1 of the radiation beam in the horizontal direction with respect to the road surface (see FIG. 13) is usually one lane width W at the maximum detection distance P _max. Is set as follows.

In this case, if the optical axis L of the optical system is fixed,
The shaded area shown in FIG. 14 becomes a blind spot, which cannot be detected until the interrupting vehicle 10 enters the area of the radiated light beam. In order to avoid such an inconvenience, it is conceivable to widen the spread angle ψ _t1 of the radiation beam.
However, if the divergence angle ψ _t1 is widened, the maximum detection distance P _max
The radiated light beam reaches the adjacent lane and detects even the vehicle traveling in the adjacent lane. Therefore, the divergence angle ψ _t1 of the radiation beam cannot be expanded so much.

Therefore, a method of controlling the direction of the radiation beam light, that is, the direction of the optical axis L, for example, the simplest method is to mechanically rotate the optical axis L and scan the radiation beam light left and right. However, in order to mechanically rotate the optical axis L of the light transmitting / receiving optical system, the device becomes large and complicated, and there is a problem in durability.

In order to overcome these difficulties, a method is considered in which a plurality of light-transmitting optical systems each including a light-transmitting lens and a semiconductor laser are provided, each optical axis is slightly shifted, and the divergence angle of the radiation beam is expanded equivalently. . FIG. 15 shows an example thereof, which is a first light-transmitting optical system including a light-transmitting lens 2-1 and a semiconductor laser 1-1, and a second light-transmitting lens 2-2 and a semiconductor laser 1-2. And a third light sending optical system including a light sending lens 2-3 and a semiconductor laser 1-3, and an optical axis L2 of the second light sending optical system and a third light sending optical system. Optical axis of optical system
L3 is slightly tilted upward and downward in the figure with respect to the optical axis L1 of the first light transmission optical system. FIG. 16 shows radiation beam lights I, II and III from the first, second and third light transmitting optical systems.
Shows the radiation status of. The radiated beam lights II and III extend to the adjacent lane within the maximum detection distance P _max , but by performing the maximum detection distance restriction with the closest distance in contact with the adjacent lane as the restriction distance, that is, at a distance beyond that. Even if the vehicle can be detected, by invalidating the detection data, the equivalent radiation beam light IV as shown in FIG. 17 can be created, and the equivalent radiation beam light IV is forwarded in the spreading areas a and b. The blind spot at the time of car interruption will be improved.

[Problems to be solved by the device]

However, according to such a method for improving the blind spot by the equivalent radiation beam IV, a plurality of light transmitting optical systems are required, that is, a plurality of semiconductor lasers and a light transmitting lens are required, which makes the device large and complicated. However, there are problems such as increased costs.

Further, since the boundary portions of the adjacent radiation beam lights are overlapped with each other, the light intensity is increased at the overlapping portions, which may cause a problem in terms of safety for human eyes.

[Means for solving the problem]

This invention has been proposed to solve such a problem, and the first invention (the invention according to claim 1) has a horizontally elongated shape relative to the emitted beam light having an elliptical cross-sectional shape that is wide in the horizontal direction. The light transmitting lens (2 ') and the reflected beam light that is emitted through this light transmitting lens and is reflected back
A light receiving element (4 ') that receives the main beam light, which is a split component of the reflected beam light in the horizontal direction, at the main light receiving unit (4-1) and the sub beam light at the sub light receiving units (4-2, 4-3). ) And the main light receiving section is selected, and if it is not recognized that there is main beam light with an intensity above a certain value, the sub light receiving section is selected, while the main light receiving section is selected and a main beam with an intensity above a certain value is selected. If it is recognized that there is light, it is checked whether the main beam light is the reflected light from within the maximum detection distance, and if it is the reflected light from within the maximum detection distance, it is determined that there is an obstacle, and the sub light receiving unit is set. If it is selected and it is recognized that there is a sub-beam light with a certain intensity or more, it is checked whether the sub-beam light is a reflected light from within the limited distance, and if it is a reflected light from within the limited distance, it is determined that there is an obstacle. It is something that is done.

The second invention (the invention according to claim 2) is a light-transmitting lens (2 ') which is horizontally long in relation to the emitted beam light having an elliptical cross-section which is wide in the horizontal direction, and one light-receiving lens in front of it. 3 ') is provided to receive the reflected beam light which is radiated through the light transmitting lens and reflected and returned through the light receiving lens, and receives the main beam light which is a split component of the reflected beam light in the horizontal direction from the main light receiving unit (4). -1), the first sub-beam light is received by the first sub-light receiver (4-2) and the second sub-beam light is received by the second sub-light receiver (4-2). And the main light receiving section is selected, and if it is not recognized that there is a main beam light with an intensity above a certain value, the sub light receiving section is selected, while the main light receiving section is selected and a main beam light with an intensity above a certain value is selected. If it is confirmed that the main beam light is It is checked whether the reflected light is from within the detection distance, and if it is the reflected light from within the maximum detection distance, it is determined that there is an obstacle, and the first sub-light receiving unit is selected, and the sub-beam light with an intensity of a certain value or more is detected. If the sub-beam light is found to be present, it is checked whether the sub-beam light is the reflected light from within the first limit distance shorter than the maximum detection distance, and if it is the reflected light from within the first limit distance, it means that there is an obstacle. If it is determined that the second sub-light receiving unit is selected and there is sub-beam light having an intensity of a certain value or more, it is determined whether the sub-beam light is the reflected light from within the second limiting distance shorter than the maximum detection distance. Check
If there is reflected light from within the second limit distance, it is determined that there is an obstacle.

[Action]

Therefore, according to this invention, in the first invention, the radiation beam emitted through the light-transmitting lens spreads in the horizontal direction. Then, the reflected beam light that returns after being reflected is divided in the horizontal direction, and is divided into main beam light and sub beam light, which are received by the main light receiving portion and the sub light receiving portion of the light receiving element. At this time, if the main light receiving section is selected and it is not recognized that there is main beam light having an intensity of a certain value or more, the sub light receiving section is selected. If the main light receiving part is selected and it is recognized that there is a main beam light with a certain intensity or more, it is checked whether the main beam light is a reflected light from within the maximum detection distance, and a reflected light from within the maximum detection distance. If so, it is determined that there is an obstacle. If the sub-light receiving unit is selected and it is recognized that there is sub-beam light with a certain intensity or more, it is checked whether the sub-beam light is reflected light from within the limited distance. It is judged that there is something.

In the second invention, the radiation beam light emitted through the light transmitting lens spreads in the horizontal direction. Then, the reflected beam of light reflected and returned is split in the horizontal direction, and is divided into a main beam of light and first and second sub-beams of light, and the main light-receiving part and the first and second sub-light-receiving parts of the light-receiving element are divided. Is received by and. At this time, if the main light receiving section is selected and it is not recognized that there is main beam light having an intensity of a certain value or more, the sub light receiving section is selected. If the main light receiving part is selected and it is recognized that there is a main beam light with a certain intensity or more, it is checked whether the main beam light is a reflected light from within the maximum detection distance, and a reflected light from within the maximum detection distance. If so, it is determined that there is an obstacle. If the first sub-light receiving unit is selected and it is recognized that there is sub-beam light having an intensity equal to or higher than a certain value, it is checked whether or not the sub-beam light is reflected light within the first limiting distance, and the first limiting distance If the light is reflected from inside, it is determined that there is an obstacle. If the second sub-light receiving section is selected and it is recognized that there is sub-beam light having an intensity equal to or higher than a certain value,
It is checked whether or not the sub-beam light is the reflected light from within the second limit distance, and if it is the reflected light from within the second limit distance, it is determined that there is an obstacle.

〔Example〕

Hereinafter, the optical radar device according to the present invention will be described in detail.

FIG. 1 is a block circuit diagram of a vehicle front monitoring device showing an embodiment of the present invention. 11, the same reference numerals as those in FIG. 11 denote the same components, and a description thereof will be omitted.

In this vehicle front monitoring device, the bonding surface of the semiconductor laser 1 is perpendicular to the road surface 12 as shown in an enlarged view of the laser chip 1-1 in FIG. FIG. 2 shows the directional characteristics of the semiconductor laser 1, where T1 is the directional characteristic in the horizontal direction with respect to the road surface 12, and T2 is the directional characteristic in the vertical direction with respect to the road surface 12. Therefore, the emitted beam of light from the semiconductor laser 1 is, as shown in FIG.
The shape of the ellipse is wide in the horizontal direction X and narrow in the vertical direction Y with respect to 12.

FIG. 4 shows a light-transmitting optical system for obtaining a radiated light beam having a width of one lane at the maximum detection distance. Here, Dt is the light transmitting lens 2
, Ft is the focal length of the light-transmitting lens 2, d is the distance from the focus Ft of the light-transmitting lens 2 to the semiconductor laser 1, θ _LD1 is the full-width half-maximum emission angle of the semiconductor laser 1 in the horizontal direction X, and θ _LD2 is the semiconductor It is the full width at half maximum emission angle of the laser 1 in the vertical direction Y.

When tan θ _LD1 and tan θ _LD2 <Dt / (ft−d), the spread angle Φ _t1 of the radiation beam in the horizontal direction X is Similarly, the divergence angle Φ _t2 in the vertical direction Y is Obtained as.

When tan θ _LD1 , tan θ _LD2 > Dt / (ft−d), the spread angle Φ ′ _t1 of the radiation beam in the horizontal direction X is Similarly, the spread angle Φ ′ _t2 in the vertical direction Y is Obtained as.

Generally, it is desirable that the light intensity distribution within the radiation beam is substantially uniform. Therefore, tan θ _LD1 , tan θ _LD2 > Dt /
(Ft-d) is selected, and the light in the shaded portion of the directional pattern T1 in FIG. 2 is not used.

On the other hand, in the present embodiment, the directional characteristics shown in FIG.
The light in the shaded portion of T1 is effectively used as the sub-beam light. That is, in the present embodiment, the main beam light M is made so as to satisfy tan θ _LD1 , tan θ _LD2 > Dt / (ft−d), but an angle portion larger than the half-value angle is effectively used as the sub beam lights SI and SII. To do. Therefore, in this embodiment, as shown in FIG. 5, the shape of the light-transmitting lens 2'is oblong in relation to the emitted beam light having an elliptical cross-sectional shape that is wide in the horizontal direction X and narrow in the vertical direction Y. I am trying. Fig. 6 shows the main beam light M, sub-beam light SI, SII
Shows the radiation status of. It should be noted that in the figure, the numerical values enclosed by □ indicate an example of the relative value of the light intensity at the center of the main beam light M and at the boundary line of each beam light. The light intensity of the sub-beam lights SI and SII is, as is clear with reference to FIG.
Although it is about 1/2 to 1/3 of the main beam light M, in the case of the sub beam lights SI and SII, the maximum detection distance is limited as will be described later, so the influence of the light intensity is small.

On the other hand, the main beam light M and the sub-beam lights SI and SII
The distinction between and is made by the light receiving optical system. FIG. 7 shows a configuration example of a general light receiving optical system. When the light receiving surface of the light receiving element 4 is placed at the focal position of the light receiving lens 3, the light receiving field Φ _r is Given in. In this embodiment, as the light receiving element 4 ', a dispersion type photodiode (three-divided photodiode) as shown in FIG. 8 is used, and the light receiving surface of the central photodiode 4-1 is used for the main beam M. , The light receiving surfaces of the left and right photodiodes 4-2 and 4-3 are used for the sub beam lights SI and SII. In this case, the light-receiving field of view Φ _r1 of the photodiode 4-1 is selected so as to extend one lane at the maximum detection distance P _max as shown in FIG. Further, the light receiving fields Φ _r2 and Φ _r3 of the photodiodes 4-2 and 4-3 are selected according to the spread of the radiation beam light.

Next, the operation of the vehicle front monitoring device will be described with reference to the flowchart shown in FIG. In FIG. 1, the emitted beam light from the semiconductor laser 1 passes through the light transmitting lens 2'and the main beam light M and the sub-beam lights SI and SII.
The radiation beam is composed of and. The emitted beam of light is reflected and returned by an obstacle such as another vehicle approaching, and is condensed on the light receiving element 4'through the light receiving lens 3'as reflected beam of light. At this time, the main beam light M is condensed on the light receiving surface of the photodiode 4-1 and the sub-beam lights SI and SII are collected into the photodiodes 4-2 and 4-3.
Focus on the light receiving surface of. That is, the reflected beam light radiated through the light transmitting lens 2'and reflected back is split in the horizontal direction, and the main beam light M and the sub-beam lights SI and SII are split.
The photodiodes 4-1 and 4-2 and 4 are divided into
Light is received at -3.

That is, according to the flowchart shown in FIG.
If the photodiode 4-1 is selected in step 101 and it is recognized in step 102 that the reflected light (main beam light) of a certain level or more (intensity of a certain level or more) is present, step 10
After confirming that the reflected light is from within the maximum detection distance P _max in step 3, it is determined that there is an obstacle in step 104. On the other hand, if it is not determined in step 102 that there is more than a certain amount of reflected light, the process proceeds to step 105 to select the photodiode 4-2, and in step 106, more than a certain amount of reflected light (sub-beam light) is generated. If it is recognized that there is an obstacle, the maximum detection distance is limited in step 107, it is confirmed that the light is reflected light from within the limited distance, and it is determined in step 104 that there is an obstacle. If it is not recognized that there is more than a certain amount of reflected light in step 106, step
When the process proceeds to step 108, the photodiode 4-3 is selected, and if it is recognized that there is a certain amount of reflected light (sub-beam light) in step 109, the maximum detection distance is limited in step 110, and reflection from within the limited distance is performed. After confirming that it is light, it is determined in step 104 that "there is an obstacle". If the determination result in steps 103, 107, 109 and 110 is NO,
In step 111, it is determined that there is no obstacle, and in step 101
Return to. According to such a procedure, the photodiode 4-
By scanning 1,4-2,4-3, the equivalent radiation beam IV as shown in FIG. 17 is produced.

As described above, according to the present embodiment, it is possible to improve the blind spot at the time of interrupting the front vehicle by providing only one light-transmitting optical system, the device does not become large and complicated, and the cost is reduced. It will be possible to provide it at low cost. Moreover, according to the present embodiment, since the boundary portion between the main beam light and the sub beam light does not overlap each other, the light intensity does not increase locally, and the safety to human eyes is improved. There is no risk of problems.

[Effect of device]

As described above, according to the optical radar device of the present invention, in the first invention, the reflected beam light that is reflected and returned is split in the horizontal direction, and is divided into the main beam light and the sub-beam light, and the main light receiving element receives the light. If the main light beam is detected by the main unit and the sub-light receiving unit and the main light receiving unit is selected and there is a main beam light with an intensity above a certain value, it is determined whether the main beam light is a reflected light from within the maximum detection distance. If the reflected light from the maximum detection distance is checked, it is determined that there is an obstacle, and if the sub-light receiving unit is selected and there is a sub-beam light with an intensity above a certain value, then the sub-beam light is within the limited distance. It is judged whether there is an obstacle if it is the reflected light from within the limited distance. In the second invention, the reflected beam light that is reflected and returned is divided in the horizontal direction, Main light receiving portion of the light receiving element and the first and second sub-beam light
If the main light-receiving part is received by the second sub-light-receiving part and the main light-receiving part is selected and it is recognized that there is main beam light having an intensity of a certain value or more, it is determined whether the main beam light is the reflected light from within the maximum detection distance. Is checked, if it is the reflected light from within the maximum detection distance, it is determined that there is an obstacle, and if the first sub-light receiving unit is selected and there is a sub-beam light with an intensity above a certain value, the sub-beam light is detected. Is a reflected light from within the first limit distance, and if it is a reflected light from within the first limit distance, it is determined that there is an obstacle, and the second sub-light-receiving unit is selected and a certain value or more is selected. If it is recognized that there is a sub-beam light with the intensity of, it is checked whether the sub-beam light is the reflected light from within the second limit distance, and if it is the reflected light from within the second limit distance, it means that there is an obstacle. Judged and provided one light-transmitting optical system In it is possible to improve the blind spot at the front wheel interrupts, system and large, without complicated, it is possible to provide inexpensive in cost.

Moreover, since the boundary between the main beam light and the sub-beam light does not overlap each other, the light intensity does not increase locally, which may cause a problem in terms of safety for human eyes. There is no.

[Brief description of drawings]

FIG. 1 is a block circuit configuration diagram of a vehicle front monitoring device showing an embodiment of an optical radar device according to the present invention, FIG. 2 is a diagram showing directional characteristics of a semiconductor laser used in the vehicle front monitoring device, and FIG. FIG. 3 (a) is an enlarged view of the joining state of the laser chip of this semiconductor laser, FIG. 3 (b) is a sectional view of the emitted beam light from this semiconductor laser, and FIG. 4 is one lane at the maximum detection distance. FIG. 5 is a view showing a light-transmitting optical system for obtaining a radiated beam of light having a width, FIG. 5 is a front view of a light-transmitting lens used in this vehicle front monitoring device, and FIG. 6 is a main beam light radiated through this light-transmitting lens. And FIG. 7 is a diagram showing a radiation state of the sub-beam light, FIG. 7 is a diagram showing a configuration example of a general light receiving optical system, and FIG. 8 is a light receiving surface of a dispersion type photodiode as a light receiving element used in the vehicle front monitoring device. Front view,
FIG. 9 is a view showing the light-receiving field of view of this distributed photodiode, FIG. 10 is a flow chart for explaining the operation of the vehicle front monitoring device, and FIG. 11 is an example of a vehicle front monitoring device proposed conventionally. Block circuit configuration diagram showing
Fig. 12 is a diagram showing the emission of beam light from a vehicle equipped with this vehicle front monitoring device to a vehicle ahead, and Fig. 13 is a horizontal spread angle of the emitted beam light with respect to the road surface in this vehicle front monitoring device. Fig. 14 is a diagram showing a blind spot when there is an interrupting vehicle in front of the vehicle front monitoring device, and Fig. 15 is a diagram showing a plurality of light transmitting optical systems, each of which is slightly displaced from the optical axis to radiate equivalently. FIG. 16 is a diagram for explaining a method for widening the divergence angle of the beam light, FIG. 16 is a diagram showing a radiation state of the beam light emitted from a plurality of light transmitting optical systems by this method,
The figure is a diagram showing the equivalent radiation beam light obtained by limiting the maximum detection distance to the radiation beam lights from the plurality of light transmitting optical systems. 1 ... Semiconductor laser, 2 '... Light transmitting lens, 3' ... Light receiving lens, 4 '... Light receiving element (dispersion type photodiode), 4-1, 4-2, 4-3 ... Photo diode, 8 '...
... Signal processing device.

Claims (2)

[Scope of utility model registration request] 1. A light-transmitting lens having a horizontally long shape relative to the emitted beam light having an elliptical cross-section that is wide in the horizontal direction, and a reflected beam light that is radiated through the light-transmitting lens and is reflected and returned. A light receiving element that receives the main beam light, which is the split component of the reflected beam light in the horizontal direction, in the main light receiving unit and the sub beam light in the sub light receiving unit, and the main beam light with an intensity above a certain value by selecting the main light receiving unit. If it is not recognized that the main beam light having the intensity of a certain value or more is selected while the main light receiving unit is selected, the main beam light is detected from within the maximum detection distance. Check whether it is a reflected light, if it is a reflected light from within the maximum detection distance, it is determined that there is an obstacle, if it is recognized that there is a sub-beam light having a certain value or more by selecting the sub-light receiving unit, An optical radar device comprising: means for checking whether or not the sub-beam light is a reflected light from within a limited distance and determining that there is an obstacle if the reflected light is within a limited distance. 2. A light-transmitting lens, which is oblong in shape facing the emitted beam light having a wide elliptical cross-section in the horizontal direction, and one light-receiving lens in front of the light-transmitting lens, which is emitted and reflected through the light-transmitting lens. The reflected beam light that returns is received through the light receiving lens, the main beam light that is a split component of the reflected beam light in the horizontal direction is received by the main light receiving unit, and the first sub beam light is received by the first sub light receiving unit. A light-receiving element that receives the second sub-beam light in the second sub-light-receiving part, and the main light-receiving part. If the main-beam light having an intensity of a certain value or more is not recognized, the sub-light-receiving part is selected. If the main light receiving section is selected and it is recognized that there is a main beam light having an intensity higher than a certain value, it is checked whether the main beam light is a reflected light from within the maximum detection distance, and whether it is within the maximum detection distance. If it is reflected light, it is determined that there is an obstacle, and if the first sub-light-receiving unit is selected and sub-beam light having an intensity of a certain value or more is recognized, the sub-beam light is shorter than the maximum detection distance. It is checked whether or not the reflected light is from within the first limiting distance, and if it is the reflected light from within the first limiting distance, it is determined that there is an obstacle, and the second sub-light-receiving unit is selected and a certain value or more is selected. If it is recognized that there is strong sub-beam light, it is checked whether the sub-beam light is the reflected light from within the second limiting distance shorter than the maximum detection distance, and the reflected light from within the second limiting distance is checked. An optical radar device comprising means for determining that there is an obstacle, if any.