阅读说明：本技术 激光雷达 (Laser radar ) 是由 野口仁志 武田英治 于 2018-12-27 设计创作，主要内容包括：激光雷达(10)具备：出射激光的光源(11)；将激光整形为在一个方向上长的线状光束(B10)并进行投射的光学系统；使线状光束(B10)在线状光束(B10)的短边方向上扫描的扫描部(15)；用于使线状光束(B10)的光强度在线状光束(B10)的长边方向上不同的结构。例如通过控制器(21)在光源(11)中控制沿着与线状光束(B10)的长边方向相对应的方向配置的多个发光部的出射功率,从而使线状光束(B10)的光强度不同。(A laser radar (10) is provided with: a light source (11) for emitting laser light; an optical system for shaping and projecting the laser light into a linear beam (B10) that is long in one direction; a scanning unit (15) that scans the linear beam (B10) in the direction of the short side of the linear beam (B10); the linear light beam (B10) has a structure in which the light intensity of the linear light beam (B10) is different in the longitudinal direction of the linear light beam. For example, the controller (21) controls the light source (11) to emit power from a plurality of light-emitting units arranged in a direction corresponding to the longitudinal direction of the linear luminous flux (B10) so as to vary the light intensity of the linear luminous flux (B10).)

1. A laser radar is provided with:

a light source emitting laser light;

an optical system that shapes the laser light into a linear beam that is long in one direction and projects the linear beam;

a scanning unit that scans the linear beam in a short-side direction of the linear beam; and

and a configuration for making the light intensity of the linear light flux different in the longitudinal direction of the linear light flux.

2. Lidar according to claim 1,

the light intensity of the linear light beam is adjusted so that the end portions in the longitudinal direction are reduced in comparison with the central portion in the longitudinal direction.

3. Lidar according to claim 1 or 2,

the light source device is provided with a control part for controlling the light source,

a plurality of light emitting units for the laser beam are arranged along a direction corresponding to the longitudinal direction,

the control unit controls the output of the light emitting unit so that the light intensity of the linear light beam is different in the longitudinal direction of the linear light beam.

4. Lidar according to claim 3, characterized in that

The control unit controls the output of the light emitting unit so that the light intensity of the linear light beam is different so that the light intensity of the linear light beam increases toward the end in the longitudinal direction as compared with the light intensity of the linear light beam at the center in the longitudinal direction.

5. Lidar according to claim 1 or 2,

the light source includes a plurality of laser diodes arranged in a direction corresponding to the longitudinal direction,

by making the emission capabilities of the plurality of laser diodes different, the light intensity of the linear light beam is made different in the longitudinal direction.

6. Lidar according to claim 1 or 2,

the optical system includes an adjustment lens for making the light intensity of the linear light beam in the longitudinal direction different in the longitudinal direction.

7. The lidar according to any one of claims 1 to 6,

the optical system includes a magnifying lens that widens the laser beam emitted from the laser diode in a direction corresponding to a longitudinal direction of the linear beam,

the scanning unit is disposed closer to the laser diode than the magnifying lens.

8. Lidar according to claim 7,

the magnifying lens has a lens surface curved in only one direction,

the scanning unit scans the laser beam in a direction parallel to a generatrix of the lens surface and scans the linear beam in the short side direction.

9. Lidar according to claim 7 or 8,

the optical system is provided with a collimating mirror,

the scanning unit is disposed between the collimator lens and the magnifying lens.

Technical Field

The present invention relates to a laser radar for detecting an object using laser light, and more particularly to a laser radar suitable for mounting on a moving body such as a passenger car.

Background

Conventionally, a laser radar that detects an object using laser light has been developed in various fields. For example, in a laser radar for vehicle mounting, laser light is projected from the front of the vehicle, and whether or not an object such as a vehicle is present in front of the vehicle is determined based on the presence or absence of reflected light of the laser light. Further, the distance to the object is measured based on the projection timing of the laser light and the light reception timing of the reflected light.

Patent document 1 below discloses a laser radar device configured to generate three-dimensional information of a measurement target region by two-dimensionally scanning a laser beam in a horizontal direction and a vertical direction.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-150990

Disclosure of Invention

Problems to be solved by the invention

As described in patent document 1, in a configuration in which a laser beam is scanned two-dimensionally in a detection target region, there is a problem in that the frame rate for acquiring information for 1 frame is significantly reduced as the resolution of the measurement position is increased.

As a method for solving this problem, a method of scanning an elongated linear beam having a length corresponding to the width of the measurement target region in the short side direction of the linear beam can be used. However, in this method, since the linear beam is projected onto the detection target region while being widened in the longitudinal direction, the energy density of the linear beam decreases as the distance to the measurement target region increases. Therefore, in order to detect an object at a longer distance, it is necessary to emit light from the light source at a high light intensity, but it is difficult to say that a random increase in light intensity is a preferable measure. Therefore, it is preferable to use the laser light emitted from the light source as efficiently as possible.

In view of the above problem, an object of the present invention is to provide a laser radar capable of more effectively using laser light emitted from a light source.

A laser radar according to a main aspect of the present invention includes: a light source emitting laser light; an optical system that shapes the laser light into a linear beam that is long in one direction and projects the linear beam; a scanning unit that scans the linear beam in a short-side direction of the linear beam; and a structure for making the light intensity of the linear light beam different in the longitudinal direction of the linear light beam.

According to the laser radar of the present aspect, since the light intensity of the linear beam is made different in the longitudinal direction of the linear beam, for example, by reducing the light intensity in a sufficiently short range of the detection distance, it is possible to detect the object more efficiently by using the laser light emitted from the light source.

Effects of the invention

As described above, according to the present invention, it is possible to provide a laser radar capable of more efficiently using laser light emitted from a light source.

The effects and significance of the present invention will be more apparent from the following description of the embodiments. However, the embodiments described below are merely examples for carrying out the present invention, and the present invention is not limited to any of the contents described in the embodiments below.

Drawings

Fig. 1 is a diagram showing the configuration of an optical system and a circuit unit of a laser radar according to an embodiment.

Fig. 2(a) and (b) are perspective views each showing a configuration of a laser diode according to the embodiment, and fig. 2 (c) is a perspective view showing a configuration of a light source of a laser radar according to the embodiment.

Fig. 3(a) and (b) are diagrams illustrating the operation of the optical system of the laser radar according to the embodiment as viewed in the longitudinal direction and the short-side direction of the linear beam, respectively.

Fig. 4 is a diagram schematically showing the emission state of the laser beam of the laser radar and the intensity distribution in the longitudinal direction of the linear beam in the target region according to the embodiment.

Fig. 5 (a) is a verification result of a preferred range of the divergence angle of the linear beam in the short side direction according to embodiment 1 verified by optical simulation. Fig. 5 (b) is a verification result of the preferred range of the width of the light-emitting section of the laser diode in the fast axis direction verified by optical simulation according to embodiment 1.

Fig. 6 (a) is a flowchart showing power control of the light source according to the embodiment. Fig. 6 (b) is a diagram schematically showing the emission state of each laser diode when the setting for reducing the emission power of the laser diodes on both sides is performed in the control of fig. 6 (a).

Fig. 7 is a diagram schematically showing the state of laser light emitted from the laser radar and the intensity distribution in the longitudinal direction of the linear beam in the target region when the setting for reducing the output power of the laser diodes on both sides is performed in the control of fig. 6 (a).

Fig. 8 (a) is a diagram showing another configuration example for reducing the output power of the laser diodes on both sides according to the embodiment. Fig. 8 (b) is a diagram showing still another configuration example for reducing the output power of the laser diodes on both sides according to the embodiment.

Fig. 9 (a) is a flowchart showing another power control of the light source according to the embodiment. Fig. 9 (b) is a diagram schematically showing emission states of the plurality of laser diodes in the case where the control of fig. 9 (a) is performed.

Fig. 10 is a diagram schematically showing the state of laser light emitted from the laser radar and the intensity distribution in the longitudinal direction of the linear beam in the target region when the setting for reducing the output power of the left laser diode is performed in the control of fig. 9 (a) according to the embodiment.

Fig. 11 is a diagram schematically showing a state in which a setting for reducing the output power of the right laser diode is performed in the control of fig. 9 (a) according to the embodiment.

Fig. 12 (a) is a flowchart showing another power control of the light source according to the embodiment. Fig. 12 (b) is a diagram schematically showing emission states of the plurality of laser diodes in the case where the control of fig. 12 (a) is performed.

Fig. 13 is a diagram schematically showing the state of laser light emitted from the laser radar and the intensity distribution in the longitudinal direction of the linear beam in the target region in the case where the setting for increasing the output power of the laser diodes on both sides is performed in the control of fig. 12 (a) according to the embodiment.

Fig. 14 (a) and (b) are perspective views each showing a configuration of a laser diode according to a modification, and fig. 14 (c) is a perspective view showing a configuration of a light source of a laser radar according to a modification.

The drawings are only for purposes of illustration and are not intended to limit the scope of the invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, X, Y, Z axes perpendicular to each other are appropriately shown in the drawings. The X-axis direction and the Y-axis direction are the short-side direction and the long-side direction of the linear beam, respectively, and the positive direction of the Z-axis is the projection direction of the linear beam.

Fig. 1 is a diagram showing the configuration of an optical system and a circuit portion of a laser radar 10.

The laser radar 10 includes a light source 11, collimator mirrors 12 and 13, a mirror 14, a scanner unit 15, an adjustment lens 16, an amplification lens 17, a condenser lens 18, and a light receiving element 19 as an optical system. A long linear beam B10 is generated in the Y axis direction from the laser light emitted from the light source 11 by the outgoing optical system from the light source 11 to the magnifying lens 17.

The light source 11 emits laser light of a predetermined wavelength. The light source 11 is formed by integrating a plurality of laser diodes. In the present embodiment, the laser radar 10 is assumed to be mounted on a vehicle. Therefore, the emission wavelength of each laser diode is set to the infrared band (for example, 905 nm). The emission wavelength of the laser diode can be appropriately changed according to the use mode of the laser radar 10.

Fig. 2(a) and (b) are perspective views each showing the structure of the laser diode 110, and fig. 2 (c) is a perspective view showing the structure of the light source 11.

As shown in fig. 2(a), the laser diode 110 has a structure in which the active layer 111 is sandwiched between the N-type cladding layer 112 and the P-type cladding layer 113. The N-type clad layer 112 is laminated on the N-type substrate 114. Further, a contact layer 115 is laminated on the P-type cladding layer 113. By applying a current to the electrode 116, laser light is emitted from the light emitting section 117 in the Z-axis positive direction. In general, the width W1 of the light-emitting portion 117 in the direction parallel to the active layer 111 is wider than the width W2 in the direction perpendicular to the active layer 111.

An axis in the short-side direction of the light emitting section 117, that is, an axis in a direction perpendicular to the active layer 111 (X-axis direction) is referred to as a fast axis, and an axis in the long-side direction of the light emitting section 117, that is, an axis in a direction parallel to the active layer 111 (Y-axis direction) is referred to as a slow axis. In fig. 2(b), 118a indicates the fast axis, and 118b indicates the slow axis. The wide angle of the laser beam emitted from the light emitting unit 117 in the fast axis direction is larger than the wide angle in the slow axis direction. Therefore, as shown in fig. 2(B), the shape of beam B20 becomes an elliptical shape that is long in the fast axis direction.

Since the width of the light-emitting portion 117 in the fast axis direction is narrow, the intensity distribution (light-emitting profile) of the light beam B20 emitted from the light-emitting portion 117 in the fast axis direction has a distribution shape close to a single gaussian. In contrast, since the intensity distribution (light emission profile) of light beam B20 emitted from light emitting unit 117 in the slow axis direction has a wide width in light emitting unit 117 in the slow axis direction, the intensity distribution (light emission profile) of light beam B20 emitted from light emitting unit 117 in the slow axis direction has a complicated distribution shape including a plurality of peaks. This makes it easier to control the optical system such as to suppress the wide angle of the light beam in the fast axis direction than in the slow axis direction, and thus makes it possible to more appropriately perform desired control.

In the present embodiment, as shown in fig. 2 (c), the light source 11 is configured by arranging a plurality of laser diodes 110 along the slow axis. Therefore, the light emitting sections 117 of the laser diodes 110 are arranged in 1 row in the slow axis direction. Here, each laser diode 110 is arranged such that the fast axis 118a of the light emitting section 117 is parallel to the direction (X-axis direction) corresponding to the short side direction of the linear beam B10 shown in fig. 1.

In the present embodiment, the plurality of laser diodes 110 constituting the light source 11 have the same emission characteristics. That is, if the same drive current is applied to any one of the laser diodes 110, the laser light is emitted at the same power.

Returning to fig. 1, the collimator lens 12 converges the laser beams emitted from the laser diodes 110 of the light source 11 in the fast axis direction and adjusts the spread of the laser beams in the fast axis direction to be substantially parallel. That is, the collimator 12 has a function of collimating the laser beams emitted from the laser diodes 110 of the light source 11 only in the fast axis direction.

The collimator lens 13 converges the laser beams emitted from the laser diodes 110 of the light source 11 in the slow axis direction and sets the spread of the laser beams in the slow axis direction to be substantially parallel. That is, the collimator lens 13 has a function of collimating the laser beams emitted from the laser diodes 110 of the light source 11 only in the slow axis direction.

The laser beams emitted from the laser diodes 110 of the light source 11 are converted into spread beams substantially parallel to each other over the entire circumference by the 2 collimator lenses 12 and 13. Further, since the light emitting section 117 is not a perfect point light source, strictly speaking, a very small positional deviation occurs between the optical axis of the collimator mirrors 12 and 13 and the light emitting point of the light emitting section 117 of each laser diode 110. Therefore, the laser light transmitted through the 2 collimator mirrors 12 and 13 does not become completely parallel light, but is in a state of being slightly spread from the parallel light.

The mirror 14 reflects the laser beam transmitted through the collimators 12 and 13 toward the scanner unit 15. The scanning unit 15 is constituted by, for example, a mems (micro electro mechanical systems) mirror. The laser light reflected by the mirror 14 is reflected by a movable mirror 15a of the scanner unit 15 in a direction toward the adjustment lens 16. The scanning unit 15 drives the movable mirror 15a by a drive signal from the mirror drive circuit 23 to scan the laser beam reflected by the mirror 14 in a direction (X-axis direction) parallel to a generatrix of the lens surface 17a of the magnifier lens 17.

The adjustment lens 16 adjusts the light intensity in the longitudinal direction (Y-axis direction) of the linear light beam B10. Specifically, the adjustment lens 16 is configured to substantially uniformize the light intensity in the longitudinal direction (Y-axis direction) of the linear light beam B10. The light intensity of the linear light beam B10 in the longitudinal direction (Y axis direction) is, for example, uniform to such an extent that the variation width of the light intensity distribution converges to ± 5%.

The magnifying lens 17 expands the laser light incident from the adjustment lens 16 only in the Y axis direction. The magnifying lens 17 includes a lens surface 17a curved only in the Y axis direction. In the present embodiment, as the magnifying lens 17, a concave lens having a lens surface 17a recessed inside is used. Instead of this, a convex lens (cylindrical lens) whose lens surface protrudes outside may be used as the magnifying lens 17. In this case, the laser light converges in the Y axis direction to form a focal line, and then expands in the Y axis direction. The magnifying lens 17 is disposed such that a generatrix of the lens surface 17a is parallel to the X axis direction. Thereby, the laser beam expands in the Y axis direction, and a linear beam B10 elongated in the Y axis direction is formed.

Fig. 3(a) and (B) are views of the action of the optical system of the laser radar 10 as viewed in the longitudinal direction and the short-side direction of the linear beam B10, respectively. For convenience, fig. 3(a) and (b) show the mirror 14, the scanning unit 15, and the adjusting lens 16 omitted, and the optical path from the light source 11 to the magnifying lens 17 is extended linearly.

The laser light emitted from the light source 11 is converged in the fast axis direction by an eye collimator 12 and collimated in the fast axis direction. At this time, the laser light is not converged in the slow axis direction. Therefore, the laser light having passed through the collimator lens 12 is expanded in the slow axis direction at a wide angle as soon as it is emitted from the light source 11.

In addition, the collimator lens 12 may further have a converging action in the slow axis direction. When the collimator lens 12 does not have a converging function in the slow axis direction, the size of a lens or a reflecting mirror located on the rear side of the collimator lens 12 may need to be increased according to the width and the wide angle of the light source 11 in the slow axis direction and the distance from the collimator lens 12. Therefore, in the configuration of the laser radar 10, even when the size of the lens and the mirror located on the rear stage side of the collimator 12 needs to be reduced, the collimator 12 may be further provided with a converging action in the slow axis direction.

Thereafter, the laser light is converged in the slow axis direction by the 2-eye collimator lens 13, and is collimated in the slow axis direction. At this time, the laser light is not converged in the fast axis direction. Therefore, the laser light after passing through the collimator lens 13 is maintained as substantially parallel light in the fast axis direction. As described above, the laser beam collimated in the fast axis direction and the slow axis direction enters the magnifier lens 17.

The 2-eye collimator 13 may have an optical function of converting the laser beam from parallel light to slightly converged light in the slow axis direction. The laser light incident on the magnifier lens 17 may be collimated in the fast axis direction, collimated or converged in the slow axis direction. The collimator lens 13 may be disposed on the front side of the collimator lens 12.

The magnifying lens 17 diffuses the incident laser light only in the slow axis direction to form a linear beam B10. Therefore, the linear beam B10 enters the target region while being collimated by the collimator lens 12 in the fast axis direction. The width of the linear beam B10 in the short-side direction is determined by the collimator lens 12 of one eye. As above, the linear light beam B10 is projected to the target region.

Fig. 4 is a diagram schematically showing the state of emission of laser light from the laser radar 10 and the intensity distribution in the longitudinal direction of the linear beam B10 in the target region. The upper part of fig. 4 schematically shows the cross-sectional shape of the linear beam B10 and the distribution of the light intensity in the longitudinal direction (Y-axis direction) of the linear beam B10 when viewed in the projection direction (Z-axis positive direction). Here, the light intensity distribution is obtained along the middle position (line L1 in fig. 4) in the short side direction of the linear light flux B10.

As shown in fig. 4, in the present embodiment, the laser radar 10 is mounted on the front side of the vehicle 20, and the linear beam B10 is projected to the front of the vehicle 20. The wide angle θ 11 in the longitudinal direction of the linear beam B10 is, for example, 120 °. The upper limit of the object-detectable distance D11 is, for example, about 200 m. In fig. 4, the wide angle θ 11 is shown smaller than it is in reality for convenience. This is also the same with respect to fig. 7, 10, and 13 to be referred to next.

In the present embodiment, when the plurality of laser diodes 110 provided in the light source 11 are driven at the same output power, the adjustment lens 16 is configured such that the intensity distribution of the linear light beam B10 in the longitudinal direction is substantially uniform. As described above, the intensity distribution of the linear light flux B10 is uniformized, and thereby the detectable distances of the objects at the respective positions in the longitudinal direction of the linear light flux B10 can be made equal to each other. The detectable distance of the object becomes longer as the intensity of the laser light increases. Therefore, if the intensity distribution of the linear light beam B10 is made uniform in the longitudinal direction as described above, the detectable distances of objects at all positions in the longitudinal direction become substantially equal.

Returning to fig. 1, the reflected light of the linear light flux B10 reflected from the target region is condensed on the light receiving surface of the light receiving element 19 by the condenser lens 18. The light receiving element 19 is, for example, an image sensor. The light receiving element 19 has, for example, a rectangular light receiving surface, and is disposed such that the long sides of the light receiving surface are parallel to each other on the Y axis. The longitudinal direction of the light receiving surface of the light receiving element 19 corresponds to the longitudinal direction of the linear light beam B10 in the target region. The reflected light of the linear light beam B10 passes through the condenser lens 18 so as to extend in the longitudinal direction of the light receiving surface, and is imaged on the light receiving surface of the light receiving element 19.

Here, the Y-axis pixel position on the light receiving surface corresponds to the Y-axis position in the target region. Therefore, it is possible to detect at which position in the Y axis direction of the target region an object is present, based on the position of the pixel generated by the light reception signal. A line sensor having pixels arranged in the Y axis direction may be used as the light receiving element 19.

The laser radar 10 includes a controller 21, a laser drive circuit 22, a mirror drive circuit 23, and a signal processing circuit 24 as a circuit portion.

The controller 21 includes an arithmetic Processing circuit such as a cpu (central Processing unit), and a storage medium such as a rom (read only memory) or a ram (random Access memory), and controls each unit according to a preset program. The laser drive circuit 22 drives each laser diode 110 of the light source 11 in accordance with control from the controller 21. The controller 21 and the laser drive circuit 22 constitute a control unit that controls the light source 11.

The mirror drive circuit 23 drives the scanning unit 15 in accordance with control from the controller 21. As described above, the controller 21 controls the scanning unit 15 so that the laser beam is scanned in a direction parallel to the generatrix of the lens surface 17a of the magnifier lens 17. Thereby, in the target region, the linear beam B10 is scanned in the short side direction of the linear beam B10.

The signal processing circuit 24 outputs the light reception signal of each pixel of the light receiving element 19 to the controller 21. As described above, the controller 21 can detect at which position in the Y axis direction of the target region the object is present, from the position of the pixel where the light reception signal is generated. The controller 21 can calculate the distance to the object existing in the target region based on the time difference between the timing of pulse emission of the light source 11 and the timing of reception of the reflected light from the target region by the light receiving element 19, that is, the timing of reception of the light receiving signal from the light receiving element 19.

As described above, the controller 21 detects the presence or absence of an object in the target region by causing the light source 11 to emit a pulse light and scanning the linear light beam B10 by the scanning unit 15, and further measures the position of the object in the Y-axis direction and the distance to the object. These measurement results are sent to the control unit on the vehicle side as needed.

< verification >

However, as described above, the laser beam emitted from the laser diode 110 passes through the collimator lens 12, and then enters the following optical path in a state where the beam is slightly widened in the fast axis direction without becoming completely parallel in the fast axis direction. Therefore, the linear light flux B10 generated by passing through the magnifying lens 17 is also slightly widened in the short-side direction. As described above, this phenomenon is caused by the fact that the light emitting portion 117 of the laser diode 110 has a width in the fast axis direction (X axis direction), and is not a perfect point light source. If the linear beam B10 becomes wider in the short side direction, the optical density of the linear beam B10 decreases as the detection distance becomes longer, and the accuracy of object detection decreases.

Therefore, the inventors verified the preferable range of the divergence angle of the linear light flux B10 in the short-side direction and the preferable range of the width of the light emitting portion 117 in the fast axis direction.

Fig. 5 (a) is a verification result of verifying a preferable range of the divergence angle of the linear light beam B10 in the short side direction by optical simulation.

In fig. 5 (a), the horizontal axis represents the ratio θ 1/θ 0 of the divergence angles in the front-rear fast axis direction of the optical system for generating the linear light flux B10. θ 1 is a divergence angle in the fast axis direction (X axis direction) of the laser beam after passing through the optical system from the collimator lens 12 to the magnifying lens 17 shown in fig. 1, and θ 0 is a divergence angle in the fast axis direction (X axis direction) of the laser beam before passing through the optical system (in other words, when the optical system is omitted).

In fig. 5 (a), the vertical axis represents the ratio D1/D0 between the object detectable distance D1 in the case where an optical system for generating the linear light beam B10 is arranged and the object detectable distance D0 in the case where the optical system is omitted. In this verification, the detectable distance means a distance at which the laser light can be irradiated at a predetermined intensity.

As shown in fig. 5 (a), the smaller the value of the ratio θ 1/θ 0, the larger the value of the ratio D1/D0, and the detectable distance is significantly increased. In particular, in the range where the value of the ratio θ 1/θ 0 is 0.1 or less, the change in the value of the ratio D1/D0 is rapid with a decrease in the ratio θ 1/θ 0. From this, it is understood that if the value of the ratio θ 1/θ 0 is 0.1 or less, the detection distance can be greatly increased. Therefore, it can be said that the ratio θ 1/θ 0 is preferably set to 0.1 or less. That is, it can be said that the wide angle of the linear light beam B10 in the short-side direction is preferably adjusted so that the ratio θ 1/θ 0 becomes 0.1 or less.

Fig. 5 (b) is a verification result of verifying a preferable range of the width of the light emitting portion 117 in the fast axis direction by optical simulation.

In fig. 5 b, the horizontal axis represents the width of the light emitting unit 117 of the laser diode 110 in the fast axis direction (corresponding to the width W2 in fig. 2 a), and the vertical axis represents the ratio θ 1/θ 0 similar to the horizontal axis in fig. 5 a.

As is clear from the verification result in fig. 5 (a), in order to extend the detectable distance in the linear beam formation, the ratio θ 1/θ 0 is preferably set to 0.1 or less. In contrast, as a result of the verification in fig. 5 (b), it is understood that the width of the light-emitting portion 117 in the fast axis direction in which the ratio θ 1/θ 0 is 0.1 or less is 240 μm or less. From this, it can be said that the width of the light emitting section 117 in the fast axis direction is preferably set to 240 μm or less.

In other words, the laser diode 110 that can be used in the range where the value of the ratio θ 1/θ 0 is 0.1 or less is a laser diode in which the maximum width of the light emitting section 117 in the fast axis direction is 240 μm, and when the laser diode 110 in which the maximum width of the light emitting section 117 in the fast axis direction exceeds 240 μm is used, the light amount of the laser diode 110 itself increases due to the increase in the light source accompanying the amplification of the light emitting section 117, but the value of the ratio θ 1/θ 0 of the increased light amount is 0.1 or more, and therefore does not contribute much to the improvement of the value of the ratio D1/D0. Therefore, this case is a wasteful design.

From the above verification, it can be said that the optical system is configured so that the value of the ratio θ 1/θ 0 is 0.1 or less. In addition, it is understood that the characteristics of the laser diode 110 are effectively used without waste by setting the width of the light emitting section 117 of the laser diode 110 in the fast axis direction to 240 μm.

In the optical system shown in fig. 3(a) and (b), the simulations of fig. 5 (a) and (b) were performed by replacing one collimator lens having the functions of both the collimator lenses 12 and 13 with the collimator lenses 12 and 13. Here, the focal length of the collimator lens is selected so that the beam diameter after transmission through the collimator lens becomes 2 mm. However, these focal length and beam diameter are not physical quantities that affect the verification results in fig. 5 (a) and (b). In the above simulation, the wavelength of the laser was set to 905 nm.

< control of light intensity 1 >

However, in the straight-ahead running of the vehicle 20, it can be assumed that the distances required for detecting the object are different between the range of the center in the front of the vehicle and the range of the sides in the front of the vehicle. That is, in order to detect a forward traveling vehicle and an oncoming vehicle in the central area of the front of the vehicle, it is preferable to detect an object at a distance as far as possible. On the other hand, since the range on the side in front of the vehicle is only required to be able to detect a walking person or a sudden jump of the vehicle from a sidewalk, a alley, or the like, it is only required to be able to detect an object in a relatively short range.

Therefore, in the present embodiment, a structure for making the light intensity of linear beam B10 different in the longitudinal direction of linear beam B10 is provided. Specifically, the controller 21 can adjust the light intensity of the linear beam B10 in the longitudinal direction by varying the output power of the plurality of laser diodes 110 constituting the light source 11.

Fig. 6 (a) is a flowchart showing the power control of the light source 11 by the controller 21.

The controller 21 includes a mode (uniform mode) in which the light intensity of the linear beam B10 is set uniformly in the longitudinal direction, and a mode (both-side reduction mode) in which the light intensity of the linear beam B10 is reduced on both sides in the longitudinal direction as compared with the center. The mode switching may be set by the user or may be set in accordance with an instruction from the vehicle-side control unit. For example, when the vehicle 20 is in a straight-ahead driving state, the vehicle-side control unit issues a command to switch the mode to the two-side lowering mode to the controller 21. Alternatively, the controller 21 may switch the mode when receiving information indicating that the vehicle 20 is in the straight-ahead driving state from the vehicle-side control unit.

If the laser radar 10 is activated, the controller 21 determines which of the uniform mode and the both-side reduction mode is set as the mode of the light intensity of the linear beam B10 at a predetermined timing (S101). Here, if it is determined that the mode is the uniform mode (S101: no), the controller 21 drives all the laser diodes 110 constituting the light source 11 with the same output power (S102). Thereby, the linear light beam B10 is projected to the target area with uniform light intensity as shown in fig. 4.

On the other hand, if it is determined that the two-sided reduction mode is in (S101: YES), the controller 21 reduces the output power of a predetermined amount of the laser diodes 110 arranged on both sides in the slow axis direction among the laser diodes 110 constituting the light source 11, to be lower than the output power of the remaining laser diodes 110 (S103).

Fig. 6 (b) is a diagram schematically showing the emission state of each laser diode 110 when the double-sided reduction mode is set under the control of fig. 6 (a). Here, for convenience, the light source 11 is constituted by 7 laser diodes 110. However, the number of laser diodes 110 constituting the light source 11 is not limited thereto.

When the two-sided lowering mode is set, the drive current C2 applied to the 2 laser diodes 110 at the Y-axis positive side end and the 2 laser diodes 110 at the Y-axis negative side end is lowered from the drive current C1 applied to the central 3 laser diodes 110. Thus, the output power of the laser diode 110 at the end to which the drive current C2 is applied is smaller than the output power of the laser diode 110 at the center to which the drive current C1 is applied. Here, the reduction in the output power of the end laser diode 110 with respect to the center laser diode 110 is set to, for example, about 25%.

In addition, the number of laser diodes 110 that reduce the output power is not limited to 4. The number of laser diodes 110 for reducing the output power can be changed as appropriate in accordance with the ratio of the range in which the light intensity is reduced in the linear beam B10, the number of laser diodes 110 constituting the light source 11, and the like.

Fig. 7 is a diagram schematically showing the state of laser light emitted from laser radar 10 and the intensity distribution in the longitudinal direction of linear beam B10 in the target region when the double-side lowering mode is set in the control of fig. 6 (a).

In the wide angle θ 11 (for example, 120 °) in the longitudinal direction of the linear light beam B10, the light intensity is maintained high in the central angular range θ 12, and the light intensity is reduced in the angular ranges θ 13 on both sides compared to the central range. Here, the angle range θ 12 is, for example, about 60 °, and the angle range θ 13 is, for example, about 30 °. Here, the angular ranges θ 12, θ 13 are not limited thereto.

When the detectable distance of the object in the central angle range θ 12 is set to about 200m and the detectable distances of the objects in the angle ranges θ 13 at both ends are set to about 100m, the decrease in the light intensity of the angle range θ 13 with respect to the light intensity of the angle range θ 12 is adjusted to about 25%, for example. The reduction in light intensity in the angle range θ 13 with respect to light intensity in the angle range θ 12 is not limited to 25%.

By making the light intensity of the linear light beam B10 different as described above, the detectable distance of the object is maintained long, for example, at about 200m in the central angle range θ 12, and the detectable distance of the object is shorter than the center in the angle ranges θ 13 at both ends. However, even if the detectable distance in the angle ranges θ 13 on both sides is reduced as described above during the straight-ahead running of the vehicle, there is little hindrance to detecting a walking person or a sudden jump of the vehicle from a sidewalk, a moustache, or the like. In addition, by reducing the light intensity at both ends as described above, the power consumption of the entire light source 11 can be reduced. Therefore, the power consumption can be reduced, and the object can be detected more efficiently.

Here, although the light intensity of linear beam B10 is made different by adjusting the drive current to each laser diode 110 constituting light source 11, the light intensity of linear beam B10 may be made different in the longitudinal direction by another method.

For example, as shown in fig. 8 (a), a plurality of laser diodes 110 having different emission capabilities may be disposed in the light source 11. That is, a plurality of laser diodes 110 that emit laser light at different emission powers even if the same drive current C0 is applied may be disposed in the light source 11.

In the example of fig. 8 (a), the emission capability of 2 laser diodes 110 at the Y-axis positive side end and 2 laser diodes 110 at the Y-axis negative side end is lower than that of the central 3 laser diodes 110 among the 7 laser diodes 110. The controller 21 applies the same drive current C0 to all the laser diodes 110. Thus, the output power of every two laser diodes 110 at both ends is lower than the output power of the central 3 laser diodes 110.

Alternatively, as shown in fig. 8 (b), the adjustment lens 16 may be configured such that the light intensity at both ends in the slow axis direction is lower than the light intensity at the center. In fig. 8 (b), for convenience, the collimator mirror 12, the mirror 14, and the scanning unit 15 are not shown.

In this configuration, all the laser diodes 110 constituting the light source 11 have the same emission capability. The controller 21 applies the same drive current C3 to all the laser diodes 110, and causes the laser beams to be emitted from the laser diodes 110 at equal power. The laser adjustment lens 16 emitted from each laser diode 110 is converted into a light flux having a high light intensity at the center and a low light intensity at both ends in the slow axis direction. Thereafter, the light beam is expanded in the slow axis direction by the magnifying lens 17. Thereby, the linear light beam B10 is generated.

With these configurations, as in fig. 7, linear beam B10 having a high light intensity at the center and low light intensities at both ends in the longitudinal direction is obtained. In these cases, the decrease in light intensity in the angular range θ 13 at both ends relative to the light intensity in the angular range θ 12 at the center is adjusted to, for example, about 25%.

In this configuration example, as in the configuration example shown in fig. 6 (a) and (B), the light intensity of linear light beam B10 cannot be switched between the uniform mode and the both-side decreasing mode. However, in these cases, the light intensity at both ends is adjusted to be lower than that at the center, and therefore the laser beam that generates the linear beam B10 can be effectively used. Thus, the detection of the object can be performed more efficiently.

< control of light intensity 2 >

In the above, the light intensity at both ends of the linear beam B10 is adjusted to be lower than that at the center, but the light intensity of the linear beam B10 is not limited to this.

For example, when the vehicle 20 is traveling on the leftmost lane of an expressway, there may be a roadside partition or a wall on the left side of the vehicle 20. In such a case, it is not necessary to remotely detect an object on the left side of the vehicle 20. Therefore, when a signal indicating the above-described state is transmitted from the vehicle-side control unit to the controller 21, the controller 21 may decrease the light intensity in the range of the linear beam B10 corresponding to the left side of the vehicle 20.

In addition, when the vehicle 20 turns right at an intersection, it is necessary to detect an object at a far left side of the vehicle 20 in order to grasp a situation where the vehicle is traveling straight ahead from opposite sides, and since the right front side of the vehicle 20 can detect a person crossing at the intersection or a vehicle stopped on a right-turn road, the object may be detected at a comparatively short distance. Therefore, in the case where a signal indicating that the vehicle 20 is turning right is transmitted from the vehicle-side control unit to the controller 21, the controller 21 may decrease the light intensity in the range of the linear beam B10 corresponding to the right side of the vehicle 20.

As described above, the light intensity of linear beam B10 may be adjusted such that the light intensity is reduced at only the end portion side in any one of the longitudinal directions of linear beam B10 as compared with the other portions.

Fig. 9 (a) is a flowchart showing power control of the light source 11 in this case.

The controller 21 determines whether or not either one of the preset right lowering condition (S201) and left lowering condition (S203) is satisfied.

Here, the right-side lowering condition is a condition for lowering the light intensity in a predetermined range on the end portion side (Y-axis negative side) of linear beam B10 corresponding to the front right side of vehicle 20. The above-described case where the vehicle 20 is in a right turn is included in the right-side lowering condition. As the right lowering condition, a condition other than that the vehicle 20 is in a right turn may be included.

The left-side reduction condition is a condition for reducing the light intensity in a predetermined range on the end portion side (Y-axis positive side) of linear beam B10 corresponding to the front left side of vehicle 20. The above-described case where the vehicle 20 is running on the leftmost lane of the expressway is included in the left-side lowering condition. As the left-side lowering condition, a condition other than that the vehicle 20 is traveling on the leftmost lane of the expressway may be included.

When the right-side lowering condition is satisfied (yes in S201), the controller 21 lowers the output power of the laser diode 110 corresponding to the vehicle right side (Y-axis negative side) among the plurality of laser diodes 110 constituting the light source 11, as compared with the other laser diodes 110 (S202). That is, in this case, the controller 21 reduces the output power of a predetermined amount of the laser diodes 110 from the Y-axis negative side among the plurality of laser diodes 110 arranged in the Y-axis direction, as compared with the other laser diodes 110.

When the left-side lowering condition is satisfied (no in S201 and yes in S203), the controller 21 lowers the output power of the laser diode 110 corresponding to the left side (Y-axis positive side) of the vehicle among the plurality of laser diodes 110 constituting the light source 11, as compared with the other laser diodes 110 (S204). That is, in this case, the controller 21 reduces the output power of a laser diode 110 of a predetermined amount from the Y-axis positive side among the plurality of laser diodes 110 arranged in the Y-axis direction, as compared with the other laser diodes 110.

If neither the right-side lowering condition nor the left-side lowering condition is satisfied (S201: no, S203: no), the controller 21 controls the light source 11 in the normal mode (S205). That is, the controller 21 causes all of the plurality of laser diodes 110 arranged in the Y axis direction to emit light in a uniform manner at the output power for long distance. In this case, the light intensity of the linear light beam B10 is the same as that shown in fig. 4. The controller 21 repeatedly executes the process of fig. 9 (a).

Fig. 9 (b) is a diagram schematically showing the emission state of the plurality of laser diodes 110 when the emission power of the left laser diode 110 is reduced in step S204 in fig. 9 (a).

Here, for convenience, the light source 11 includes 7 laser diodes 110. As in the case of fig. 6 (b), the 7 laser diodes 110 have the same emission capability. The controller 21 sets the drive current C2 applied to the 2 laser diodes 110 at the Y-axis positive end lower than the drive current C1 applied to the other laser diodes 110.

Fig. 10 is a diagram schematically showing the state of laser light emitted from the laser radar 10 and the distribution of light intensity in the longitudinal direction of the linear beam B10 in the target region when the setting is made to reduce the output power of the left laser diode 110 in step S204 in fig. 9 (a).

In the angle range θ 14 at the left end of the wide angle θ 11 (for example, 120 °) of the linear light beam B10 in the longitudinal direction, the light intensity is reduced as compared with the other angle ranges θ 15. The light intensity in the angle range θ 15 is maintained high as in the case of fig. 4. The angle range θ 14 is, for example, about 30 °, and the angle range θ 15 is, for example, about 90 °. However, the angular ranges θ 14, θ 15 are not limited to this case.

When the detectable distance of the object in the angle range θ 15 is set to about 200m and the detectable distance of the object in the angle range θ 14 on the left end is set to about 100m, the decrease in the light intensity of the angle range θ 14 with respect to the light intensity of the angle range θ 15 is adjusted to about 25%, for example. The decrease in light intensity in the angle range θ 14 with respect to light intensity in the angle range θ 15 is not limited to 25%.

By making the light intensity of the linear light beam B10 different as described above, the detectable distance of the object is maintained long, for example, at about 200m in the angle range θ 15, and the detectable distance of the object is shorter than the center in the angle range θ 14 on the left end. However, when the vehicle travels on the leftmost lane of the expressway, since the roadside banks or walls are present on the left side of the vehicle, the vehicle travel is hardly affected even if the detectable distance in the left angle range θ 14 is reduced as described above. Therefore, by reducing the light intensity at the left end as described above, the power consumption can be reduced, and the object detection can be performed more efficiently.

When the setting to decrease the output power of the right laser diode 110 is performed in step S202 in fig. 9 (a), the controller 21 performs control to decrease the output power of the rightmost laser diode 110 and the 2 nd laser diode 110 from the right among the 7 laser diodes 110 shown in fig. 9 (b), for example, as compared with the other laser diodes 110.

Fig. 11 is a diagram schematically showing a situation in which the setting for reducing the output power of the right laser diode 110 is performed in step S202 in fig. 9 (a).

Here, an example is shown in which the output power of the right laser diode 110 is reduced on the condition that the vehicle 20 makes a right turn at the intersection J10.

When the vehicle 20 makes a right turn from the road R10 at the intersection J10 and enters the right-turn road R20, control is performed to reduce the light intensity with respect to a predetermined range of the right end portion of the linear beam B10 during a period from the start of the right turn to the end of the right turn of the vehicle 20. This reduces the detectable distance of the object in a predetermined range of the right end of the linear beam B10. In other ranges of the linear light beam B10, the light intensity is maintained high, and therefore the detectable distance of the object is secured long as in the case of fig. 4.

Here, it can be said that when the vehicle 20 is turning right at the intersection J10, it is necessary to perform the distant object detection on the front left side of the vehicle 20 in order to grasp the situation of the oncoming vehicle traveling in reverse on the front road R30. On the other hand, the right front side of the vehicle 20 may be capable of detecting the person 30 crossing the crosswalk at the intersection J10, the vehicle parked on the right-turning road R20, and the like, and therefore may be capable of detecting an object at a relatively short distance. Therefore, when the vehicle 20 is turning right, even if the light intensity is reduced in the range of the linear beam B10 corresponding to the right side of the vehicle 20 and the detectable distance of the object is reduced, the traveling of the vehicle 20 is not hindered. Therefore, by reducing the light intensity at the right-side end portion at the time of the right turn as described above, the power consumption can be reduced, and the object detection can be performed more efficiently.

In step S202 of fig. 9 (a), the number of laser diodes 110 for reducing the output power and the reduction width may be changed for each type of the right-side reduction condition satisfied in step S201. In addition, when the vehicle 20 turns right, the number of laser diodes 110 for reducing the output power and the width may be changed in accordance with the rotation angle from the neutral position of the handle.

Similarly, in step S204 of fig. 9 (a), the number of laser diodes 110 for reducing the output power and the reduction width may be changed for each type of the left-side reduction condition satisfied in step S203. In addition, the number of laser diodes 110 for reducing the output power and the reduction width may be changed according to the traveling speed of the vehicle 20. That is, in the group of laser diodes 110 for which the output power is reduced, the output power may be further made different for each laser diode 110 according to a predetermined condition such as a traveling state.

< control of light intensity 3 >

In the above, the light intensity at both ends or one end of linear beam B10 is adjusted to be lower than the light intensity at the center, but the method of making the light intensity of linear beam B10 different is not limited to this.

For example, when the vehicle 20 is traveling on a general road or the like at a low speed, a person or a vehicle may jump out from the right and left sides of the vehicle 20 to the front. Therefore, it is preferable to improve the detection sensitivity of the object in the front left and front right of the vehicle 20 during low-speed traveling. Further, when the vehicle 20 is traveling on a normal road or the like at a low speed, the vehicle 20 is highly likely to make a right turn or a left turn. Thus, it is effective to increase the detection sensitivity of the right front side and the left front side of the vehicle 20 in advance in preparation for the right turn and the left turn of the vehicle 20 during low-speed running.

Therefore, it is preferable to perform control such that the light intensity in the left and right end regions of linear beam B10 is higher than the light intensity in the center during low-speed traveling. Specifically, when a signal indicating that the vehicle 20 is traveling at a low speed is transmitted from the vehicle-side control unit to the controller 21, the controller 21 may increase the light intensity in the range of the linear beam B10 corresponding to the left and right sides of the vehicle 20. The controller 21 may also determine whether the vehicle 20 is in the low-speed travel state based on speed information input from the vehicle 20 side. Alternatively, a signal indicating that the vehicle 20 is in a low-speed running state may be input to the controller 21 from the vehicle 20 side.

Here, the low-speed running state is a running state in which the vehicle 20 runs on a normal road at a low speed. For example, the state where the vehicle 20 travels at a speed of 40km or less is a low-speed travel state. The upper limit speed of the low-speed travel state is not limited to this. Alternatively, the low-speed travel state may be defined as a state in which the vehicle 20 is traveling on an ordinary road whose speed is limited to a low speed. For example, when the vehicle 20 is equipped with a navigation system, the controller 21 may determine that the vehicle 20 is in a low-speed traveling state based on information received from the vehicle 20 side indicating that a road on which the vehicle 20 is traveling is a general road whose speed limit is equal to or less than a predetermined speed (for example, 40km per hour).

Fig. 12 (a) is a flowchart showing power control of the light source 11 according to control example 3.

The controller 21 determines whether a preset both-side rising condition is satisfied (S301).

Here, the two-side rising condition is a condition for raising the light intensity in a predetermined range on the end portion side (Y-axis positive side and Y-axis negative side) of linear beam B10 corresponding to the front left side and the front right side of vehicle 20. The case where the vehicle 20 is in the low-speed running state is included in the two-sided ascent condition. The conditions other than that of the vehicle 20 in the low-speed running state may also be included as the two-sided ascent conditions.

When the two-side rising condition is satisfied (yes in S301), the controller 21 increases the output power of the laser diode 110 corresponding to the left side (Y-axis positive side) and the right side (Y-axis negative side) of the vehicle 20 among the plurality of laser diodes 110 constituting the light source 11, as compared with the other laser diodes 110 (S302). That is, in this case, the controller 21 increases the output power of the laser diode 110 of a predetermined amount from the Y-axis positive side and the output power of the laser diode 110 of a predetermined amount from the Y-axis negative side among the plurality of laser diodes 110 arranged in the Y-axis direction, as compared with the other laser diodes 110. In this case, the light intensity near the center of the linear light beam B10 is set to be approximately the same as the light intensity shown in fig. 4.

In the case where the both-side rising condition is not satisfied (S301: no), the controller 21 controls the light source 11 in the normal mode (S303). The control of step S303 is the same as the control of step S205 of fig. 9 (a). The controller 21 repeatedly executes the process of fig. 12 (a).

Fig. 12 (b) is a diagram schematically showing emission states of the plurality of laser diodes 110 when the emission power of the laser diodes 110 on both sides is increased in step S303 in fig. 12 (a).

Here, for convenience, the light source 11 includes 7 laser diodes 110. As in the case of fig. 6 (b), the 7 laser diodes 110 have the same emission capability. The controller 21 sets the drive current C4 to be applied to the 2 laser diodes 110 at the Y-axis positive-side end and the 2 laser diodes 110 at the Y-axis negative-side end higher than the drive current C1 to be applied to the other laser diodes 110.

Fig. 13 is a diagram schematically showing the state of laser light emitted from laser radar 10 and the distribution of light intensity in the longitudinal direction of linear beam B10 in the target region when the setting is made to increase the output power of laser diodes 110 on both sides in step S302 in fig. 12 (a).

In the wide angle θ 11 (for example, 120 °) in the longitudinal direction of the linear light beam B10, and in the left end angle range θ 16 and the right end angle range θ 16, the light intensity is increased as compared with the other angle ranges θ 17. The light intensity of the angle range θ 17 is set to be the same as in the case of fig. 4. The angle range θ 16 is, for example, about 30 °, and the angle range θ 17 is, for example, about 90 °. The angular ranges θ 16 and θ 17 are not limited to these. Further, the increase in the light intensity of the angle range θ 16 with respect to the light intensity of the angle range θ 17 is adjusted to, for example, a 25% level. The increase in light intensity in the angle range θ 16 with respect to light intensity in the angle range θ 17 is not limited to 25%.

By making the light intensity of the linear light beam B10 different as described above, the detection sensitivity of the object can be improved in the angular range θ 16 on both sides compared to the center.

In step S301 in fig. 12 (a), it may be determined whether or not a plurality of both-side rising conditions are satisfied. For example, the first both-side rising condition may be satisfied when the speed of the vehicle 20 is 30km or less at the speed, and the second both-side rising condition may be satisfied when the speed is greater than 30km at the speed and 40km or less at the speed. When the first both-side rising condition is satisfied, the output power of the 2 laser diodes 110 rises from the end as shown in fig. 12 (b). In the case where the second two-sided rising condition is satisfied, the output power of one laser diode 110 rises from the tip. As described above, the lower the speed of the vehicle 20 is in the ordinary road, the more reliably the objects on both sides of the vehicle 20 can be detected.

In step S301 in fig. 12 (a), the output power of the laser diode 110 may be adjusted according to a right-side rising condition including the vehicle 20 being in a right turn and a left-side rising condition including the vehicle 20 being in a left turn. That is, when the right-side elevation condition is satisfied, the output power of the laser diode 110 corresponding to the right side of the vehicle 20 may be increased more than that of the other laser diodes 110, and when the left-side elevation condition is satisfied, the output power of the laser diode 110 corresponding to the left side of the vehicle 20 may be increased more than that of the other laser diodes 110.

< effects of the embodiment >

As described above, according to the present embodiment, the following effects can be achieved.

As described with reference to fig. 2(a) to (c), the fast axis 118a of the laser diode 110, which is easier to optically control, is arranged along the direction corresponding to the short side direction (X axis direction) of the linear beam B10. Therefore, the wide angle of the light flux in the short-side direction of the linear light flux B10 can be adjusted to be closer to parallel light. Therefore, a decrease in the energy density of the linear beam B10 in the short-side direction can be effectively suppressed, and the object can be detected at a longer distance.

As shown in fig. 2 (c), a plurality of laser light emitting units 117 are arranged along the slow axis direction of the laser diode 110. This can effectively increase the light amount of the linear beam B10. As described with reference to fig. 6 (a) to 7, 9 (a) to 11, and 12 (a) to 13, the light intensity of the linear beam B10 can be smoothly varied in the longitudinal direction by individually controlling the laser diodes 110.

In the configuration of fig. 2 (c), the plurality of light emitting units 117 are arranged along the slow axis direction by arranging and integrating the plurality of laser diodes 110 along the slow axis direction, but the laser diode 110 may be configured such that the plurality of light emitting units 117 are provided along the slow axis direction in one laser diode 110.

As shown in the verification result of fig. 5 (a), it is preferable that the optical system is configured such that when the divergence angle in the fast axis direction of the laser light before the optical system for generating the linear beam B10 is transmitted is θ 0, and the divergence angle in the fast axis direction of the laser light after the optical system is transmitted is θ 1, θ 1/θ 0 is 0.1 or less. This can significantly increase the detectable distance of the object.

As shown in the verification result of fig. 5 (b), the width of the light emitting section 117 in the fast axis direction of the laser diode 110 is preferably 240 μm or less. This can efficiently use the characteristics of the laser diode 110 without waste, and can efficiently increase the detectable distance of the object.

In the present embodiment, as shown in fig. 1, the scanner unit 15 is disposed on the light source 11 side (laser diode 110 side) of the magnifying lens 17. This makes it possible to introduce laser light having a small beam diameter before being expanded by the magnifying lens 17 into the scanning unit 15, and thus, a small-sized and highly responsive scanning unit 15 can be used. Therefore, the linear beam B10 can be smoothly and appropriately scanned while reducing the cost.

In the present embodiment, as described with reference to fig. 1, the magnifying lens 17 includes the curved lens surface 17a in only one direction, and the scanning unit 15 scans the laser beam in the direction (X-axis direction) parallel to the generatrix of the lens surface 17a and scans the linear beam B10 in the short-side direction. By scanning the laser beam in the direction parallel to the generatrix of the lens surface 17a as described above, it is possible to suppress the optical action imparted to the laser beam from the magnifying lens 17 from becoming large as the laser beam is scanned. Therefore, the beam cross section of the linear beam B10 can be stabilized, and the object detection accuracy can be improved.

In the present embodiment, as shown in fig. 1, the scanning unit 15 is disposed between the collimator lenses 12 and 13 and the magnifying lens 17. This makes it possible to introduce laser light having a small beam diameter, which is collimated, into the scanning unit 15, and to use a small-sized and highly responsive scanning unit 15. Therefore, the linear beam B10 can be smoothly and appropriately scanned while reducing the cost.

In the present embodiment, as shown in fig. 1, the optical system for generating the linear luminous flux B10 includes an adjustment lens 16 for adjusting the light intensity of the linear luminous flux B10 in the longitudinal direction. As a result, for example, as shown in fig. 4, the light intensity of linear light beam B10 can be made substantially uniform in the longitudinal direction of linear light beam B10, and an object can be detected accurately at all positions in the longitudinal direction. Alternatively, as shown in fig. 8 (B), the light intensity of linear beam B10 may be adjusted to be different in the longitudinal direction of linear beam B10 by adjusting lens 16.

As shown in fig. 6 (a) to 13, the light intensity of linear beam B10 is made different in the longitudinal direction of linear beam B10, whereby the laser light emitted from light source 11 can be used more efficiently.

For example, as shown in fig. 6 (a) to 8 (B), the light intensity of linear beam B10 is adjusted so that both end portions of linear beam B10 in the longitudinal direction are reduced from the central portion in the longitudinal direction, whereby the laser light can be used more efficiently during straight traveling. That is, in the vehicle front where it is necessary to detect an object at a long distance, the detectable distance can be ensured to be long by maintaining the normal light intensity, and in the vehicle side where the object at a short distance is sufficient to detect, the detectable distance can be shortened by lowering the light intensity. This enables more efficient use of the laser light emitted from the light source 11.

As shown in fig. 9 (a) to 11, by adjusting the light intensity of linear beam B10 so that the light intensity at one end portion in the longitudinal direction of linear beam B10 is lower than the light intensity at the center portion in the longitudinal direction, the laser light can be used more efficiently during traveling on an expressway or during a right turn at an intersection.

For example, when the vehicle 20 is traveling on the leftmost lane of an expressway, the roadside banks and walls are continuous on the left side of the vehicle 20, and thus, remote object detection is not required. Therefore, in this case, the detectable distance is shortened by reducing the intensity of the left end portion of the linear beam B10, and the object detection can be appropriately performed by using the laser light more efficiently.

Alternatively, when the vehicle 20 is turning right at an intersection, it is sufficient that a person crossing a crosswalk can be detected on the right side of the vehicle 20 and the vehicle is stopped, and thus long-distance object detection is not necessary. Therefore, in this case, by reducing the intensity of the right end portion of the linear beam B10 to shorten the detectable distance, the object detection can be appropriately performed by using the laser light more efficiently.

As shown in fig. 12 (a) to 13, the light intensity of linear beam B10 is made different so as to increase at the end portion side in the longitudinal direction of linear beam B10 as compared with the central portion in the longitudinal direction, thereby improving the detection sensitivity on the left and right sides of vehicle 20. Thus, when the vehicle 20 travels on a normal road or the like at a low speed, it is possible to more reliably detect a person or a turning vehicle that may jump out from the left and right sides of the vehicle 20, and to reliably detect a right front person at the time of a right turn, a turning vehicle, and a left front person or a turning vehicle at the time of a left turn.

In the case where light source 11 is configured by arranging a plurality of light emitting portions 117 in a direction corresponding to the longitudinal direction of linear light beam B10 as shown in fig. 2 (c), it is preferable that the light intensity of linear light beam B10 is made different in the longitudinal direction of linear light beam B10 by controlling the output of each light emitting portion 117 by controller 21 as shown in fig. 6 (a), 9 (a), and 12 (a). This enables the light intensity of linear beam B10 to be dynamically adjusted according to various situations.

However, for example, when the light intensity of the linear beam B10 is fixed to the intensity distribution shown in fig. 7, the adjustment lens 16 may be configured so that the light intensity of the linear beam B10 may be different in the longitudinal direction by making the emission capabilities of the plurality of laser diodes 110 different as shown in fig. 8 (a), or the light intensity of the linear beam B10 in the longitudinal direction may be different as shown in fig. 8 (B).

< modification >

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and various other modifications are possible.

For example, in the above-described embodiment, as shown in fig. 2 (c), the light source 11 is configured such that the plurality of light emitting sections 117 are arranged in the slow axis direction, but the light source 11 may be configured such that the light emitting sections 117 are also arranged in the fast axis direction.

Fig. 14 (a) to (c) are diagrams showing a configuration example of this case.

In this configuration example, as shown in fig. 14 (a), a plurality of light emitting sections 117 are provided in a single laser diode 110 and arranged in the fast axis direction (X axis direction). A group of an active layer 111, an N-type clad layer 112, and a P-type clad layer 113 is laminated between an N-type substrate 114 and a contact layer 115 via a channel bonding layer 119. Thereby, 3 light emitting portions 117 are formed.

As in the case of fig. 2(a), the width W1 of the light-emitting portion 117 in the direction parallel to the active layer 111 is wider than the width W2 in the direction perpendicular to the active layer 111. By applying a drive current to the electrodes 116, laser light is emitted from each of the 3 light-emitting sections 117 as shown in fig. 14 (b). The wide angle of light beam B20 in the direction parallel to fast axis 118a increases compared to the wide angle in the direction parallel to slow axis 118B. Therefore, the light beam B20 has an elliptical shape elongated in the fast axis direction.

In this configuration example, as shown in fig. 14 (c), the plurality of laser diodes 110 are arranged in the slow axis direction to constitute the light source 11. Thereby, the plurality of light emitting portions 117 are arranged not only in the slow axis direction but also in the fast axis direction.

In this configuration example, the number of light emitting portions 117 is increased as compared with the configuration of fig. 2 (c), and therefore the light amount of linear beam B10 can be increased. However, since the positions of the upper and lower light emitting sections 117 are shifted from the optical axis of the collimator lens 12, the laser beams emitted from these light emitting sections 117 easily spread from the parallel light. Therefore, in this configuration, it is preferable that the interval between the light emitting sections 117 arranged in the fast axis direction be narrowed. From the verification result in fig. 5 (b), it can be said that the distance between the uppermost light-emitting portion 117 and the lowermost light-emitting portion 117 is preferably 240 μm or less. The number of light-emitting units 117 arranged in the fast axis direction is not limited to 3, and may be other numbers such as 2.

In this configuration example, the light intensity of linear light beam B10 may be made different in the longitudinal direction by the same method as that described with reference to fig. 6 (a) to 13.

In the above embodiment, the laser light is collimated by using 2 collimator lenses 12 and 13, but the laser light may be collimated by one collimator lens having the functions of both the collimator lenses 12 and 13. In the optical system shown in fig. 1, the laser beam is guided to the scanning unit 15 by the mirror 14, but the mirror 14 may be omitted and the laser beam transmitted through the collimator mirror 13 may be directly incident on the scanning unit 15. In addition, the configuration of the optical system that generates the linear beam B10 can be changed as appropriate.

In the above-described embodiment, the laser diode 110 is arranged such that the fast axis 118a of the light emitting portion 117 of the laser diode 110 is parallel to the direction (X-axis direction) corresponding to the short side direction of the linear beam B10, but the fast axis 118a of the light emitting portion 117 may not be strictly parallel to the direction corresponding to the short side direction of the linear beam B10, or may be slightly inclined from being parallel to the direction corresponding to the short side direction of the linear beam B10. Further, in the case where the width of the linear beam B10 in the short side direction is not strictly controlled, the fast axis 118a of the light emitting section 117 may be inclined largely with respect to the direction (X-axis direction) corresponding to the short side direction of the linear beam B10, and for example, the fast axis 118a of the light emitting section 117 may be perpendicular to the direction (X-axis direction) corresponding to the short side direction of the linear beam B10.

In the above-described embodiment, in the control shown in fig. 6 (a) to 13, the light intensity of the linear light flux B10 is adjusted so that the light intensity of both ends or one end of the linear light flux B10 in the longitudinal direction is reduced or increased, but the portion where the light intensity is reduced may not necessarily be the end of the linear light flux B10 in the longitudinal direction. The portion where the light intensity is reduced can be variously changed according to the state of the target region where the linear light beam B10 is projected.

In the above embodiment, the laser radar 10 is mounted on the vehicle 20, but the laser radar 10 may be mounted on another moving object. The laser radar 10 may be mounted on a device or apparatus other than a mobile body.

In addition, the embodiments of the present invention can be modified in various ways as appropriate within the scope of the technical idea shown in the claims.

Description of the symbols

10 … lidar

11 … light source

12. 13 … collimating mirror

15 … scanning part

16 … adjusting lens

17 … magnifying lens

17a … lens surface

21 … controller

22 … laser driving circuit

110 … laser diode

117 … light emitting part

118a … fast axis

118b … slow axis

B10 … line beam.