JP2019039848A - Object detection device - Google Patents

Abstract

To accurately detect both an object located at a long distance and an object located at a short distance.SOLUTION: An object detection device 100 rotates a mirror 4a of a rotary scanning unit 4, reflects a laser beam projected from any one of a plurality of LDs (laser diodes) provided in an LD group 2a with the mirror 4a to scan a predetermined range, and reflects light reflected on an object 50 with the mirror 4a to guide the light to any one of a plurality of PDs (photo diodes) provided in a PD group 7a. The object detection device sequentially switches the LD to emit light, sequentially switches the PD to receive the reflected light corresponding to the LD in a light emitting state, and detects the object 50 on the basis of a light receiving signal output from the PD in a light receiving state. The mirror 4a is provided with a first reflection surface 4b and a second reflection surface 4c that do not belong to the same plane and reflect light; the first reflection surface 4b is formed of a specular surface, and the second reflection surface 4c includes a diffuse reflector.SELECTED DRAWING: Figure 1B

Description

  The present invention relates to an object detection apparatus that projects light from a light emitting element, receives reflected light by a light receiving element, and detects an object based on a light reception signal output from the light receiving element.

  For example, an object detection device such as a laser radar is mounted on a vehicle having a collision prevention function. This object detection device projects light from a light emitting element, receives the reflected light by a light receiving element, and based on a light reception signal output from the light receiving element, determines the presence or absence of the object and the distance to the object. To detect.

  A laser diode or the like is used as the light emitting element. As the light receiving element, a photodiode, an avalanche photodiode, or the like is used. A plurality of light emitting elements and light receiving elements may be used to project and receive light over a wide range. Further, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or the like may be used instead of the light receiving element.

  Furthermore, there are also object detection devices having a function of scanning or dispersing light in the horizontal direction and the vertical direction in order to project and receive light over a wide range, downsize the device, and the like (for example, Patent Documents 1 to 3). 3).

  The object detection device of Patent Document 1 includes a rotation scanning unit having a hexahedral mirror. The central axis perpendicular to the upper and lower surfaces of the mirror is the rotation axis. The four side surfaces of the mirror are reflecting surfaces and are inclined at different angles with respect to the rotation axis. By rotating the mirror around the rotation axis, the projection light projected from the light emitting element (laser light source) is reflected by each reflecting surface of the mirror and scanned within a predetermined range. Further, the reflected light reflected by the object within the predetermined range is reflected by each reflecting surface of the mirror and guided to the light receiving element (photodetector). At the time of light projection and reception, the projection light and the reflected light are scanned not only in the horizontal direction but also in the vertical direction.

  The object detection device of Patent Document 2 includes a first scanning mirror and a second scanning mirror. Each of these scanning mirrors is formed in a plate shape, and the plate surface is a reflection surface. By changing the angle of the first scanning mirror by the controller, the light projected from the light emitting element is reflected by the first scanning mirror and scanned within a predetermined range. Further, by changing the angle of the second scanning mirror by the controller, the reflected light reflected by the object within the predetermined range is reflected by the second scanning mirror and guided to the light receiving element.

  The object detection apparatus of Patent Document 3 includes a half mirror and two diffractive optical elements. The half mirror separates the light projected from the light emitting element and makes it incident on each diffractive optical element. Each diffractive optical element converts light incident from the half mirror into dot pattern light and irradiates different predetermined areas.

  The same angular resolution cannot be obtained when the object is at a long distance and when the object is at a short distance with respect to the object detection device, and the detection accuracy of the object is different. This is because the irradiation state of the projection light from the object detection device to the object is different between the case where the object is at a long distance and the case where the object is at a short distance (Patent Document 3), or the reflected light from the object This is because the state of incidence on the object detection device is different, or the image formation state of reflected light by a lens or the like in the object detection device is different (Patent Document 1). For this reason, if it is going to raise the detection accuracy of the target object in a long distance, the detection accuracy of the target object in a short distance will fall.

  Therefore, in order to improve not only the detection accuracy of a target object at a long distance but also the detection accuracy of a target object at a short distance, Patent Document 1 discloses an optical path length from a light emitting element to a conjugate image of a light emitting element by a light projecting lens. Is set to infinity, and the optical path length from the light receiving element to the conjugate image of the light receiving element by the light receiving lens is set to a position closer to infinity. Moreover, in patent document 3, the light projected from the light emitting element is converted into dot pattern light by a plurality of diffractive optical elements, and is irradiated onto a predetermined region in a wide angle range.

  In the background art of Patent Document 2, a large number of light receiving elements are provided in an array, and a light receiving element corresponding to the scanning position of the projection light from the light emitting element is selected by a multiplexer, and the light received from the light receiving element is received. It is disclosed to detect an object based on a signal. As a result, noise components included in the received light signal are reduced, but the circuit scale becomes large. Therefore, in Patent Document 2, in order to increase the detection accuracy of an object at a short distance without increasing the circuit scale, information on the distance to the object detected earlier and the first scanning mirror at the time of projection are used. The angle of the second scanning mirror is controlled based on the angle information.

JP 2014-52366 A JP 2014-219250 A JP 2012-237604 A

  When the object is at a long distance, the geometrical deviation between the optical path of the projected light and the optical path of the reflected light is small, so that the reflected light from the object is applied to the light receiving element corresponding to the light emitting element that emitted the projected light. By receiving light, the presence or absence of the object and the distance to the object can be accurately detected based on the light reception signal output from the light receiving element. However, when the object is at a short distance, the geometrical deviation between the optical path of the projected light and the optical path of the reflected light becomes large, so that an angle difference occurs between the optical path of the projected light and the optical path of the reflected light. The reflected light may not enter the light receiving element corresponding to. For this reason, even if the light receiving element corresponding to the light emitting element receives the reflected light, the presence or absence of the object and the distance to the object cannot be accurately detected based on the light reception signal output from the light receiving element. There is a fear.

  This invention makes it a subject to provide the target object detection apparatus which can detect both the target object in a long distance and the target object in a short distance accurately.

  An object detection apparatus according to the present invention includes a plurality of light emitting elements that project light, a plurality of light receiving elements that receive light and output a light reception signal, and a mirror. By rotating the mirror, the light emitting element A rotation scanning unit that reflects the projection light projected from the mirror and scans within a predetermined range, and reflects the reflected light of the projection light from an object in the predetermined range by the mirror and guides it to the light receiving element, and emits light. The light emitting elements are sequentially switched, and the projection light from the light emitting elements in the light emitting state is scanned within a predetermined range by the rotary scanning unit, and the light receiving elements that receive the reflected light corresponding to the light emitting elements in the light emitting state are sequentially switched to receive the light. The object is detected based on the light reception signal output from the light receiving element in the state. In this configuration, the mirror has a first reflecting surface and a second reflecting surface that do not belong to the same plane and each reflects light, the first reflecting surface is formed of a specular reflecting surface, and the second reflecting surface is diffused. Includes a reflective surface.

  According to the above, when the projection light projected from one of the light emitting elements and the reflected light from the object of the projection light are specularly reflected by the first reflection surface of the mirror of the rotary scanning unit, the projection light Is reflected by the object at a long distance, the reflected light from the object enters the light receiving element corresponding to the light emitting element that projected the projection light. For this reason, by causing the light receiving element corresponding to the light emitting element in the light emitting state to receive the reflected light, it is possible to accurately detect an object at a long distance based on the light reception signal output from the light receiving element.

  Further, when the projection light projected from one of the light emitting elements is diffusely reflected by the second reflecting surface of the mirror of the rotary scanning unit, each projection light hits the object from different directions, and the projection light Reflected light from the object enters the plurality of light receiving elements from different directions. Also, when the reflected light is diffusely reflected by the second reflecting surface, the reflected light enters the plurality of light receiving elements from different directions. At this time, since the reflected light is incident on more light receiving elements than the number of light receiving elements corresponding to the light emitting elements in the light emitting state, even if the reflected light is reflected light from an object at a short distance, The reflected light can be easily incident on the light receiving element corresponding to the light emitting element. For this reason, it is possible to accurately detect an object at a short distance based on the light reception signal output from the light receiving element.

  In the present invention, the rotation scanning unit reflects the projection light on each reflection surface of the mirror and scans within a predetermined range, reflects the reflection light on each reflection surface and guides it to the light receiving element, and projects the projection light on the second reflection surface. The incident part or the incident part of the reflected light may be constituted by a diffuse reflection surface.

  In the present invention, the width of the second reflecting surface parallel to the scanning surface of the projection light by the rotary scanning unit may be smaller than the width of the first reflecting surface parallel to the scanning surface.

  In the present invention, the mirror may be formed in a plate shape, the first reflection surface may be provided on the mirror plate surface, and the second reflection surface may be provided on a side surface having a smaller area than the mirror plate surface.

  In the present invention, the diffuse reflection surface may have a mirror shape that diffusely reflects incident light.

  Moreover, in this invention, you may further provide the signal selection part which selects the light reception signal output from the light reception element of a light reception state among several light reception elements as a light reception signal for target object detection.

  Further, in the present invention, the plurality of light emitting elements are arranged so as to be aligned perpendicular to the scanning surface of the projection light by the rotational scanning unit, and the rotational scanning unit reflects the projection light by the first reflecting surface and falls within a predetermined range. During the first scanning period, a plurality of light emitting elements are caused to emit light sequentially, the reflected light is sequentially received by the light receiving elements corresponding to the light emitting elements in the light emitting state, and the rotation scanning unit reflects the projection light by the second reflecting surface. Then, in the second scanning period in which scanning is performed within a predetermined range, a specific light emitting element among the plurality of light emitting elements may be caused to emit light at a predetermined period, and reflected light may be sequentially received by the plurality of light receiving elements.

  Further, in the present invention, in the first scanning period, the presence / absence of the target object, the direction of the target object, or the distance to the target object is detected based on the light emitting state of the light emitting element and the light reception signal, and the second scanning period. In addition, at least the presence or absence of the object may be detected based on the light emission state of the light emitting element and the light reception signal.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the target object detection apparatus which can detect both the target object in a long distance, and the target object in a short distance accurately.

It is the figure which showed the state which looked at the optical system of the target object detection apparatus by embodiment of this invention from upper direction. It is the figure which showed the state which the angle of the mirror of FIG. 1A changed. It is the figure which showed the state which looked at the optical system of the target object detection apparatus of FIG. 1A from back. It is the figure which showed the state which looked at the optical system of the target object detection apparatus of FIG. 1B from back. It is a front view of LD group of Drawing 1A. It is a front view of PD group of FIG. 1A. It is a perspective view of the mirror of the rotation scanning part of FIG. 1A. It is the figure which showed the electrical structure of the target object detection apparatus of FIG. 1A. It is the figure which showed the light projection state of the 1st scanning period of the target object detection apparatus of FIG. 1A. It is the figure which showed the light projection / reception state of the 1st scanning period with respect to the target object in a long distance. It is the figure which showed the light projection / reception state of the 1st scanning period with respect to the target object in a short distance. It is the figure which showed the light projection / reception state of the 2nd scanning period with respect to the target object in a short distance. It is the figure which showed the light projection / reception timing of a 1st scanning period. It is the figure which showed the light projection / reception timing of a 2nd scanning period. It is a perspective view of the mirror of the rotation scanning part by other embodiment of this invention. It is a perspective view of the mirror of the rotation scanning part by other embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

  First, the structure and operation of the optical system of the object detection apparatus 100 according to the present embodiment will be described with reference to FIGS. 1A to 5.

  1A and 1B are diagrams showing a state in which the optical system of the object detection apparatus 100 is viewed from above. 1A and 1B, the angle of the mirror 4a is different. FIG. 2A is a diagram illustrating a state in which the optical system of the object detection apparatus 100 in FIG. 1A is viewed from the rear (the lower side in FIG. 1A, that is, the side opposite to the object 50). 2B is a diagram illustrating a state in which the optical system of the object detection apparatus 100 in FIG. 1B is viewed from the rear (lower side in FIG. 1B, that is, the side opposite to the object 50).

  The object detection device 100 is constituted by, for example, a laser radar mounted on an automobile. The optical system of the object detection apparatus 100 includes an LD (Laser Diode) group 2a, a light projecting lens 14, a rotation scanning unit 4, a light receiving lens 16, a reflecting mirror 17, and a PD (Photo Diode) group 7a.

  Among them, the LD group 2a, the light projecting lens 14, and the rotation scanning unit 4 are light projecting optical systems. The rotation scanning unit 4, the light receiving lens 16, the reflecting mirror 17, and the PD group 7a are a light receiving optical system.

  These optical systems are accommodated in the case 19 of the object detection apparatus 100. The front surface of the case 19 (the object 50 side) is open. A transmission window 20 is provided on the front surface of the case 19. The transmission window 20 is composed of a rectangular window frame and a light-transmitting plate material fitted in the window frame (detailed illustration is omitted).

  The object detection device 100 is installed at the front, rear, or left and right sides of the vehicle so that the transmission window 20 faces the front, rear, or left and right sides of the vehicle. The target object 50 is a preceding vehicle, a person, or other object outside the target object detection apparatus 100.

FIG. 3 is a front view of the LD group 2a (view of the light emitting surface side). The LD group 2a is composed of a plurality of LD ₁ to LD ₈ . In FIG. 3, the light emitting surfaces of LD _{1 to} LD ₈ are shown. LD _{1 to} LD ₈ are light emitting elements that project high-power laser light (light pulses). A plurality of LD _{1 to} LD ₈ are arranged in the vertical direction (the same direction as the vertical direction in FIG. 2) so that the light emitting surface faces the rotation scanning unit 4 side. Hereinafter, LD ₁ to LD ₈ are collectively referred to as LD.

FIG. 4 is a front view of the PD group 7a (view of the light receiving surface side). The PD group 7a is composed of a plurality of PIN type PD ₁ to PD ₁₆ . In FIG. 4, the light receiving surfaces of PD _{1 to} PD ₁₆ are shown. PD _{1 to} PD ₁₆ are light receiving elements that receive laser light (projection light) projected from LD _{1 to} LD ₈ and light reflected by the object 50 of the laser light. A plurality of PD _{1 to} PD ₁₆ are arranged in the vertical direction (the same direction as the vertical direction in FIG. 2) and the horizontal direction (the same direction as the horizontal direction in FIGS. 1A to 2) so that the light receiving surface faces the reflecting mirror 17 side. Has been. Hereinafter, PD ₁ to PD ₁₆ are collectively referred to as PD.

  The rotation scanning unit 4 shown in FIGS. 1A to 2B is also called a rotating mirror or an optical deflector. The rotary scanning unit 4 includes a mirror 4a and a motor 4f.

  FIG. 5 is a perspective view of the mirror 4 a of the rotation scanning unit 4. The mirror 4a is formed in a rectangular plate shape. On both plate surfaces (front and back surfaces) of the mirror 4a, a first reflecting surface 4b is provided over the entire surface. The entire surface of the first reflecting surface 4b is composed of a specular reflecting surface that specularly reflects incident light.

  On both side surfaces in the longitudinal direction of the mirror 4a, second reflecting surfaces 4c are provided over the entire surface. The entire surface of the second reflecting surface 4c is composed of a mirror-shaped diffuse reflecting surface that diffusely reflects incident light. Specifically, for example, a diffuse reflector (plate-like material, film body, powder, or the like) or a convex mirror (parabolic mirror, etc.) is attached to both sides of the mirror 4a, or uneven processing or curved surface processing is performed. For example, a second reflecting surface 4c made of a diffuse reflecting surface is provided. Moreover, you may provide the 2nd reflective surface 4c which consists of a diffuse reflective surface by methods other than this.

  The first reflecting surface 4b and the second reflecting surface 4c do not belong to the same plane and are orthogonal. Moreover, the area of the 2nd reflective surface 4c is narrower than the area of the 1st reflective surface 4b.

  As shown in FIGS. 2A and 2B, a motor 4f is provided below the mirror 4a. The mirror 4a is fixed to the upper end of the rotating shaft 4j so that the rotating shaft 4j of the motor 4f and the central axis 4q of the mirror 4a coincide. The rotation axis 4j and the central axis 4q are parallel to the vertical direction and parallel to the first reflection surface 4b and the second reflection surface 4c. The mirror 4a rotates around the central axis 4q in conjunction with the rotational axis 4j of the motor 4f.

  In the case 19, the light receiving lens 16, the reflecting mirror 17, and the PD group 7 a are arranged around the upper part of the mirror 4 a of the rotary scanning unit 4. The LD group 2a and the projection lens 14 are arranged around the lower part of the mirror 4a. A light shielding plate 18 is provided above the LD group 2 a and the light projecting lens 14 and below the light receiving lens 16. The light shielding plate 18 is fixed in the case 19 and divides the light projecting path and the light receiving path. The transmission window 20 is provided between the rotation scanning unit 4 and the scanning range of the laser beam, and divides the inside and the outside of the object detection device 100.

  The light projecting / receiving path for detecting the object 50 is as shown by the one-dot and two-dot chain arrows in FIGS. 1A to 2B. Specifically, as shown by the one-dot chain line arrows in FIGS. 1A to 2B, the laser light projected from each LD of the LD group 2 a is adjusted to spread by the light projecting lens 14, and then the rotation scanning unit. The light enters the lower half area of any of the reflecting surfaces 4b and 4c of the four mirrors 4a.

  At this time, when the motor 4f rotates and the angle (orientation) of the mirror 4a changes, for example, as shown in FIG. 1A, one of the first reflecting surfaces 4b faces the LD group 2a and the object 50 side. At a predetermined angle. Then, as indicated by the one-dot chain line arrow, the laser beam is specularly reflected by the first reflecting surface 4 b, passes through the transmission window 20, and is projected onto a predetermined range outside the case 19. At this time, the projection optical axis of the laser light is unidirectional.

  Further, as shown in FIG. 1B, when any of the second reflecting surfaces 4c reaches a predetermined angle facing the LD group 2a and the object 50 side, the laser light is reflected by the second light as indicated by a one-dot chain line arrow. The light is diffusely reflected by the reflection surface 4 c, passes through the transmission window 20, and is projected onto a predetermined range outside the case 19. At this time, the projection optical axes of the respective laser beams are different in the horizontal direction and the vertical direction.

  Further, any one of the reflecting surfaces 4b and 4c is rotated within a predetermined angle range facing the LD group 2a and the object 50, so that the laser light is reflected by the reflecting surfaces 4b and 4c and horizontally in the predetermined range. Scanned in the direction. Further, as described above, a plurality of LDs are provided in the vertical direction in FIGS. 2A and 2B, that is, in the direction perpendicular to the laser beam scanning plane (horizontal plane) by the rotary scanning unit 4. For this reason, the laser beam is scanned in the vertical direction (vertical direction) by sequentially projecting the laser beam from each LD and rotating the mirror 4a.

  A period during which the rotary scanning unit 4 reflects the laser light projected from the LD on the first reflecting surface 4b and scans the laser light within a predetermined range is hereinafter referred to as a first scanning period. In addition, a period in which the laser beam projected from the LD is reflected by the second reflecting surface 4c and scanned in a predetermined range by the rotary scanning unit 4 is hereinafter referred to as a second scanning period.

  As shown in FIG. 1A, the width W2 of the second reflecting surface 4c parallel to the scanning surface by the rotational scanning unit 4 of the laser light projected from the LD is equal to the first reflecting surface 4b parallel to the scanning surface. It is narrower than the width W1. For this reason, the 2nd scanning period using the 2nd reflective surface 4c becomes shorter than the 1st scanning period using the 1st reflective surface 4b.

  A scanning angle range Z shown in FIG. 1A is a predetermined range (in a top view) in the horizontal direction in which the laser beam from the LD is reflected by the first reflecting surface 4b of the mirror 4a and projected from the object detection device 100. That is, the scanning angle range Z is a horizontal detection range of the object 50 by the first reflecting surface 4b of the object detection device 100.

  Although not shown, the horizontal detection range of the object 50 by the second reflecting surface 4c, that is, the laser beam projected from the LD is reflected by the second reflecting surface 4c, and the object detecting device 100 is detected. The predetermined range projected from is smaller than the scanning angle range Z. This is because the width W2 of the second reflecting surface 4c is narrower than the width W1 of the first reflecting surface 4b, and the second reflecting surface 4c rotates in an orbit closer to the LD group 2a and the projection lens 14 than the first reflecting surface 4b. Because. However, for example, by adjusting the distance of the second reflecting surface 4c to the LD group 2a or the light projecting lens 14, the diffuse reflectance of the second reflecting surface 4c, the shape or performance of the light projecting lens 14, etc., the second reflection is achieved. The horizontal detection range of the object 50 by the surface 4c can be made substantially equal to the horizontal detection range of the object 50 by the first reflection surface 4b. Since the second reflecting surface 4c diffuses and reflects the laser light, the vertical detection range of the object 50 by the second reflecting surface 4c is wider than the vertical detection range of the object 50 by the first reflecting surface 4b. Become.

  As indicated by the one-dot chain line arrow in FIG. 1A, the laser light that is specularly reflected by the first reflecting surface 4 b and projected onto the predetermined range is reflected by the object 50 that is within the predetermined range. Then, the reflected light passes through the transmission window 20 and hits the upper half region of the first reflection surface 4b of the mirror 4a, as shown by the two-dot chain line arrow.

  At this time, when the motor 4f rotates and the angle (orientation) of the mirror 4a changes, for example, as shown in FIG. 1A, one of the first reflecting surfaces 4b faces the light receiving lens 16 and the object 50 side. At a predetermined angle. Then, as indicated by a two-dot chain line arrow in FIGS. 1A and 2A, the reflected light from the object 50 is specularly reflected by the first reflecting surface 4 b and enters the light receiving lens 16. The incident optical axis of the reflected light at this time is one direction. The reflected light is collected by the light receiving lens 16, then specularly reflected by the reflecting mirror 17 and received by the PD of the PD group 7 a.

  In addition, as indicated by a one-dot chain line arrow in FIG. 1B, the laser light diffusely reflected by the second reflecting surface 4c and projected onto the predetermined range is reflected by the object 50 within the predetermined range. Then, each reflected light passes through the transmission window 20 from different directions and hits the upper half region of the second reflecting surface 4c of the mirror 4a, as indicated by a two-dot chain line arrow.

  At this time, when the motor 4f rotates and the angle (orientation) of the mirror 4a changes, for example, as shown in FIG. 1B, one of the second reflecting surfaces 4c faces the light receiving lens 16 and the object 50 side. At a predetermined angle. 1B and 2B, each reflected light from the object 50 is diffusely reflected by the second reflecting surface 4c and enters the light receiving lens 16, as indicated by a two-dot chain line arrow. The incident optical axis of the reflected light at this time is different in the horizontal direction and the vertical direction. Each reflected light is collected by the light receiving lens 16, then specularly reflected by the reflecting mirror 17, and received by the PD of the PD group 7 a.

  Further, any one of the reflecting surfaces 4b and 4c rotates within a predetermined angle range facing the light receiving lens 16 and the object 50, so that the reflected light from the object 50 existing in the predetermined range is reflected on the reflecting surface 4b, The light is reflected by 4c and received by the PD of the PD group 7a through the light receiving lens 16 and the reflecting mirror 17. That is, the rotation scanning unit 4 scans the reflected light from the object 50 existing in a predetermined range in the horizontal direction and guides it to the PD through the light receiving lens 16 and the reflecting mirror 17.

  As shown in FIG. 1A and FIG. 2A, the second reflecting surface 4c as shown in FIG. 1B and FIG. 2B than when light is projected and received on the object 50 via the first reflecting surface 4b. In the case where light is projected and received via the object 50, the light diffuses, so that the number of PDs on which the reflected light from the object 50 is incident increases.

  Next, the electrical configuration of the object detection apparatus 100 will be described with reference to FIG.

  FIG. 6 is an electrical configuration diagram of the object detection apparatus 100. The object detection apparatus 100 includes a control unit 1, a light emitting module 2, an LD driving circuit 3, a motor 4f, a motor driving circuit 5, an encoder 6, a light receiving module 7, comparators 8a and 8b, an ADC (Analog to Digital Converter) 9a, 9b, a storage unit 11, and a communication unit 12.

  The control unit 1 includes a microcomputer and controls the operation of each unit of the object detection device 100. The control unit 1 is provided with an object detection unit 1a.

  The storage unit 11 includes a volatile or nonvolatile memory. The storage unit 11 stores information for the control unit 1 to control each unit of the object detection device 100, information for detecting the object 50, and the like.

  The communication unit 12 includes a communication circuit for communicating with an ECU (Electronic Control Device) mounted on the vehicle. The control unit 1 transmits and receives various information to and from the ECU through the communication unit 12.

  The light emitting module 2 includes an LD group 2a and a capacitor 2c for causing each LD of the LD group 2a to emit light. In FIG. 6, for convenience, the LD is not shown, and one block of the capacitor 2c is shown.

  The controller 1 controls the operation of each LD in the LD group 2a by the LD drive circuit 3. Specifically, the control unit 1 causes each LD to emit light by the LD driving circuit 3 and projects a laser beam. In addition, the control unit 1 stops the light emission of each LD by the LD driving circuit 3 and charges the capacitor 2c from which the charge has been discharged.

  The motor 4 f is a drive source that rotates the mirror 4 a of the rotary scanning unit 4. The controller 1 controls the drive of the motor 4f by the motor drive circuit 5 to rotate the mirror 4a. Then, as described above, the control unit 1 rotates the mirror 4a to reflect the laser light projected from the LD by any of the reflection surfaces 4b and 4c, and scans the laser beam within a predetermined range. The reflected light reflected by the object 50 is reflected by one of the reflecting surfaces 4b and 4c and guided to the PD group 7a. At this time, the control unit 1 detects the rotation state (rotation angle, rotation number, etc.) of the motor 4f and the mirror 4a based on the output of the encoder 6.

  The light receiving module 7 includes a PD group 7a, a TIA (Trans Impedance Amplifier) 7b, a MUX (Multiplexer) 7c, and high-speed amplifiers 7d and 7e. A plurality of TIAs 7b are provided so as to be paired with the PDs of the PD group 7a. In FIG. 6, two sets of PD and TIA 7b are representatively shown, but the third and higher sets of PD and TIA 7b are similarly provided. There are 16 sets of PD and TIA 7b, and each set constitutes a light receiving channel. That is, the light receiving module 7 is provided with a plurality of light receiving channels (16 channels in total).

  The cathode of each PD is connected to the power supply + V. The anode of each PD is connected to the input end of each TIA 7b. The output terminal of each TIA 7b is connected to the MUX 7c. Each PD receives a light and outputs a current (light reception signal). Each TIA 7b converts the current flowing through the connected PD into a voltage signal and outputs it to the MUX 7c.

  The MUX 7c selects the voltage signal output from the plurality of TIAs 7b and outputs it to any one of the high-speed amplifiers 7d and 7e. The high-speed amplifiers 7d and 7e switch the gain at high speed, amplify the output signal of the MUX 7c, and output the amplified signal to the comparators 8a and 8b. As a result, a voltage signal corresponding to the light receiving state of each PD is sequentially output from the light receiving module 7 to the comparators 8a and 8b. The MUX 7c is an example of the “signal selection unit” in the present invention.

  Two sets of high-speed amplifiers 7d and 7e, comparators 8a and 8b, and ADCs 9a and 9b are provided in pairs. This is to increase the speed by processing the light reception signal output from the light reception module 7 in two systems.

  The comparator 8a compares the output signal of the high-speed amplifier 7d with a predetermined threshold, and distinguishes whether the output signal is a reflected light signal based on the reflected light from the object 50 or noise. The comparator 8b compares the output signal of the high speed amplifier 7e with a predetermined threshold value, and discriminates whether the output signal is a reflected light signal based on the reflected light from the object 50 or noise. Specifically, when the output signals of the corresponding high-speed amplifiers 7d and 7e are larger than the threshold value, the comparators 8a and 8b indicate a predetermined signal (for example, a high level signal) to indicate that the output signal is a reflected light signal. Output to the corresponding ADC 9a, 9b. The comparators 8a and 8b do not output a predetermined signal to the ADCs 9a and 9b to indicate that the output signal is noise when the output signals of the high-speed amplifiers 7d and 7e are equal to or lower than the threshold value.

  As another example, the comparators 8a and 8b may output another predetermined signal (for example, a low level signal) to the ADCs 9a and 9b when the output signals of the high-speed amplifiers 7d and 7e are equal to or lower than the threshold value. There is no need to output at all.

  The ADCs 9a and 9b convert analog signals (predetermined signals) output from the corresponding comparators 8a and 8b into digital signals at high speed and output the digital signals to the control unit 1. Specifically, when a predetermined signal is output from the comparators 8 a and 8 b, the ADCs 9 a and 9 b convert the predetermined signal into a digital “1” signal and output it to the control unit 1. Further, when a predetermined signal is not output from the comparators 8 a and 8 b, the ADCs 9 a and 9 b output a digital “0” signal to the control unit 1.

  As described above, a light reception signal (voltage signal) corresponding to the light reception state of each PD is output from the light reception module 7 to the control unit 1 via the comparators 8a and 8b and the ADCs 9a and 9b.

  The object detection unit 1a of the control unit 1 determines the presence / absence of the object 50, the distance to the object 50, and the like based on the output signals of any of the ADCs 9a and 9b during the first scanning period and the second scanning period. To detect. Specifically, for example, the object detection unit 1a detects the presence or absence of the object 50 based on the “1” signal and / or the “0” signal output from the ADCs 9a and 9b.

  For example, the object detection unit 1a detects the projection time of the laser beam from the LD, and based on the “1” signal and / or the “0” signal output from the ADCs 9a and 9b, the object of the laser beam The light reception time of the reflected light by 50 is detected. Then, the distance to the object 50 is calculated based on the laser light projection time and the reflected light reception time. Specifically, the TOF (Time of Flight) of the laser light projected from the LD is detected, and the distance to the object 50 is calculated based on the TOF.

  Next, the light projection / reception state with respect to the target object 50 of the target object detection apparatus 100 will be described with reference to FIGS.

  FIG. 7 is a diagram illustrating a light projection state of the object detection apparatus 100 in the first scanning period. FIG. 8 is a diagram illustrating a light projecting / receiving state in the first scanning period of the object detection apparatus 100 with respect to the object 50 at a long distance. FIG. 9 is a diagram illustrating a light projecting / receiving state in the first scanning period of the object detection apparatus 100 with respect to the object 50 at a short distance. FIG. 10 is a diagram illustrating a light projecting / receiving state in the second scanning period of the object detection apparatus 100 with respect to the object 50 at a short distance.

  7 to 10 schematically show the LD group 2a, the PD group 7a, the light projecting lens 14, the mirror 4a, and the light receiving lens 16 in the object detection apparatus 100 for convenience. Moreover, the up-down direction of FIGS. 7-10 is the same as the up-down direction of FIGS. 2-5, and is a perpendicular direction.

As described above, LD _{1 to} LD ₈ are arranged in the vertical direction in the LD group 2a. In the PD group 7a, pairs of PD _{1 to} PD ₁₆ are arranged in the vertical direction.

In the first scanning period, the laser light projected from the LD is specularly reflected by the first reflecting surface 4b of the mirror 4a of the rotary scanning unit 4 via the light projecting lens 14, and a predetermined range in the vertical direction within a predetermined range. Projected in the direction. Specifically, as indicated by the one-dot chain line arrow in FIG. 7, the laser light L ₁ projected from the LD ₁ at the uppermost position is projected to a predetermined range at the most downward projection angle (angle with respect to the horizontal direction). Is done. The laser beam L ₈ projected from the LD _{8 at the} lowest position is projected in a predetermined range at the most upward projection angle (angle with respect to the horizontal direction). The laser beam L ₄ projected from the intermediate LD ₄ is projected horizontally within a predetermined range (see also FIGS. 8 and 9). The laser beams L ₂ and L ₃ projected from the LD ₂ and LD ₃ are projected downward in a predetermined range at different projection angles that are smaller than the projection angle of the LD ₁ and larger than the projection angle of the LD ₄ according to the arrangement position. The laser beams L _{5 to} L ₇ respectively projected from the LD _{5 to} LD ₇ are projected upward in a predetermined range at different projection angles that are smaller than the projection angle of the LD ₈ and larger than the projection angle of the LD ₄ according to the arrangement position. .

  By the way, when the case where the laser beam projected from one of the LDs through the first reflecting surface 4b of the rotary scanning unit 4 is reflected by the object 50 at a long distance of, for example, 100 m is considered, Since LD and PD are very close to each other, the LD and PD can be regarded as being approximately at the same position. Therefore, the optical path of the projection light projected from the LD onto the object 50 and the optical path of the reflected light reflected by the object 50 can be regarded as substantially parallel. The reflected light is received by the PD corresponding to the LD that has projected the laser light.

Specifically, for example, as shown in FIG. 8, the reflected light R ₄ of the object 50 a at a long distance of the laser light L ₄ projected from the LD ₄ through the first reflecting surface 4 b in the horizontal direction is , substantially parallel to the laser beam L ₄ as shown by an arrow indicated by the two-dot chain line, that is incident on the transmission window 20 at an angle of approximately 0 ° with respect to the horizontal direction. Then, it is specularly reflected by the first reflecting surface 4b and received by the PD ₇ and PD ₈ corresponding to the LD ₄ via the light receiving lens 16 and the like. Although not shown, the reflected light of the laser light projected from the LD ₁ through the first reflecting surface 4b enters the transmission window 20 substantially parallel to the laser light, and the first reflecting surface 4b. via such light receiving lens 16 and is received by the _PD 1, PD ₂ which corresponds to the LD _1. The reflected light of the laser light projected from the LD ₂ through the first reflecting surface 4b enters the transmission window 20 substantially parallel to the laser light, and passes through the first reflecting surface 4b and the light receiving lens 16 and the like. Thus, the light is received by PD ₃ and PD ₄ corresponding to LD ₂ . Similarly, the reflected light of the laser light projected from the LD ₃ to LD ₈ through the first reflecting surface 4b is incident on the transmission window 20 substantially parallel to each laser light, and corresponds to each LD. Light is received by the PD.

  On the other hand, when the laser beam projected from any LD through the first reflecting surface 4b of the rotary scanning unit 4 is reflected by the object 50 at a short distance of, for example, less than 10 m, the object 50 is considered. Therefore, it is difficult to regard the projection light and the reflected light as substantially parallel. For this reason, the reflected light from the object 50 may enter the transmission window 20 at an angle that is not parallel to the projected laser light. In this case, the reflected light is not received by the PD corresponding to the LD projecting the laser light.

Specifically, for example, as shown in FIG. 9, the reflected light R of the laser beams L ₄ projected from the LD _{4 in} the horizontal direction via the first reflecting surface 4 b at the objects 50 b and 50 c at a short distance. _b and R _c do not enter the transmission window 20 parallel to the laser beam L _{4 and} are oblique to the transmission window 20 at a predetermined downward angle with respect to the laser beam L ₄ as indicated by the two-dot chain line arrows. Is incident on. For this reason, the reflected lights R _b and R _c are not received by the PD ₇ and PD ₈ corresponding to the LD ₄ via the first reflecting surface 4b and the light receiving lens 16, and the PD ₁₃ not corresponding to the LD ₄ is received. It is received by the ~PD _16.

Further, as the object 50b, the distance to 50c is shortened, the laser beam _{L 4} and the reflected light _R b, the angle between _{R c} increases. Thus, reflected light _{R b} by the object 50b is received by _PD 13, _{PD 14,} the reflected light _{R c} by the object 50c in a closer object 50b is received by _PD 15, _{PD 16.} Although not shown, the reflected light from the objects 50b and 50c of the laser light projected from the other LD through the first reflecting surface 4b is not received by the PD corresponding to each LD. Then, the light is received by a PD that does not correspond.

On the other hand, in the second scanning period, for example, as indicated by a one-dot chain line arrow in FIG. 10, the laser light L ₄ projected from the LD ₄ passes through the light projecting lens 14 and is a mirror 4 a of the rotary scanning unit 4. The second reflection surface 4c is diffusely reflected and diffused and projected in a multidirectional angle in a vertical direction within a predetermined range. In this case, the multilingual direction in the horizontal direction of the predetermined range, the laser beam L ₄ are diffused projected.

Each laser light L _4, which are spread projected as the object 50b at a short distance, strikes from different directions to 50c. Therefore, the object 50b of the laser beam _{L 4,} reflected light _R b at 50c, _{R c} is incident from above the direction from the projection direction of the laser beam _{L 4} to the transmission window 20. Then, each of the reflected lights R _b and R _c is diffusely reflected by the second reflecting surface 4 c and received by the plurality of PD ₅ to PD ₁₆ of the PD group 7 a via the light receiving lens 16 and the like. At this time, corresponding to the LD ₄ in which projects a laser beam _{L 4 PD} 7, _{PD 8} even reflected light _R b, _{R c} is received.

  Thus, at the time of light projection / reception by the second reflection surface 4c, the reflected light of the laser beam on the object 50 enters more PDs than at the time of light projection / reception by the first reflection surface 4b shown in FIGS. To do. The PD on which the reflected light is incident includes a PD corresponding to the LD on which the laser light is projected. Similarly, the reflected light of the laser beam projected from another LD and diffusely reflected by the second reflecting surface 4c is received by many PDs including the PDs corresponding to the LD.

  Further, the number and position of PDs on which the reflected light from the object 50 at a short distance in the second scanning period is incident vary depending on the diffuse reflectance of the second reflecting surface 4c, the position and form of the object 50, and the like. However, the number of PDs on which the reflected light is incident is larger than the number of PDs corresponding to the LDs that project the laser light. In addition, since the laser light and the reflected light are diffusely reflected by the second reflecting surface 4c, the reflected light from the object 50 at a short distance is easily incident on the PD corresponding to the LD on which the laser light is projected.

  Note that the PD is received by the PD during the second scanning period because the area of the second reflecting surface 4c is smaller than the area of the first reflecting surface 4b, or the laser beam or the reflected light is diffusely reflected by the second reflecting surface 4c. There is a concern that the intensity of the reflected light becomes weak. However, since the reflected light of the laser light from the object 50 at a short distance is stronger than the reflected light of the laser light from the object 50 at a long distance, the reflected light received by the PD in the second scanning period. Is sufficiently high to detect the object 50 by the object detection unit 1a. In addition, the area of the second reflecting surface 4c and the diffuse reflectance may be set so that the intensity of the reflected light received by the PD in the second scanning period is equal to or higher than a predetermined level.

  By the way, the presence direction of the object 50a at a long distance can be detected based on the position of the PD that receives the reflected light. On the other hand, since the original laser light and reflected light are diffusely reflected in a random direction by the second reflecting surface 4c, the existence direction of the objects 50b and 50c at a short distance is the position of the PD that has received the reflected light. Cannot be detected. For this reason, in the second scanning period using the second reflecting surface 4c, the presence or absence of the object 50 at a short distance and the distance to the object 50 are detected by the object detection unit 1a. In the first scanning period using the first reflecting surface 4b, the object detection unit 1a detects the presence / absence of the object 50 at a long distance, the distance to the object 50, and the direction in which the object 50 exists. Is done.

  Next, the light projection / reception timing of the object detection apparatus 100 will be described with reference to FIGS. 11 and 12.

  FIG. 11 is a diagram illustrating the light projecting / receiving timing of the object detection apparatus 100 in the first scanning period. FIG. 12 is a diagram showing the light projecting / receiving timing of the object detection apparatus 100 in the second scanning period.

11 and 12, the horizontal direction represents time, and the vertical direction represents LD ₁ to LD ₈ , PD _{1 to} PD ₁₆ , ADCs 9a and 9b. The bars in the right-down diagonal lines represent the periods during which LD _{1 to} LD ₈ perform the light emission operation. Right up hatched bars _performs the PD 1 _{-PD 16} is receiving operation, represents a period for selecting at MUX7c the light reception signal from the _PD 1 _{-PD 16.} The bars of the diagonal lattice represent periods during which the ADCs 9a and 9b are driven to perform analog-digital conversion of the received light signals.

  In the first scanning period in which the laser beam from the LD group 2a is reflected by the first reflecting surface 4b of the mirror 4a and scanned in a predetermined range by the rotary scanning unit 4, the object 50 at a long distance (the object 50a in FIG. 8). Etc.).

For this reason, in the first scanning period (hereinafter referred to as “one first scanning period”) in which the laser beam from the LD group 2a is reflected by one first reflecting surface 4b and scanned within a predetermined range (hereinafter, referred to as “one first scanning period”). As shown in FIG. 11, the plurality of LD ₁ to LD ₈ are caused to emit light sequentially. In detail, the light emission from LD ₁ to LD ₈ is sequentially performed once in order. In FIG. 11, the sequential light emission of LD _{1 to} LD ₈ is repeated once, but the number of repetitions may be set as appropriate. As a result, laser light is projected from LD ₁ to LD ₈ , and the laser light is scanned in the horizontal direction and the vertical direction within a predetermined range by the rotary scanning unit 4. After the light emission of each LD, the control unit 1 charges the capacitor 2c (FIG. 6) from which the charge has been discharged.

Also, in one of the first scanning period, the control unit 1 among the plurality of _PD 1 _{-PD 16,} the reflected light is sequentially received by the _PD 1 _{-PD 16} corresponding to _LD 1 to Ld ₈ of the light emitting state, receiving The light reception signals output from the PD ₁ to PD _{16 in the} state are sequentially selected by the MUX 7c. Specifically, first, when the LD ₁ emits light, the corresponding PD ₁ and PD ₂ receive reflected light, and the light reception signal from the PD _{1 is} selected by the MUX 7c, and the comparator is connected via the high-speed amplifier 7d. Output to 8a. Further, the light reception signal from PD _{2 is} selected by MUX 7c and output to comparator 8b via high-speed amplifier 7e.

Next, when the LD ₂ emits light, the corresponding PD ₃ and PD ₄ receive the reflected light, and the light reception signal from the PD _{3 is} selected by the MUX 7c and output to the comparator 8a via the high-speed amplifier 7d. . In addition, the light reception signal from the PD _{4 is} selected by the MUX 7c and output to the comparator 8b via the high-speed amplifier 7e. Next, when the LD ₃ is caused to emit light, the PD ₅ and PD ₆ corresponding thereto receive the reflected light, and the light reception signal from the PD _{5 is} selected by the MUX 7c and output to the comparator 8a via the high-speed amplifier 7d. . Further, the light reception signal from the PD _{6 is} selected by the MUX 7c and output to the comparator 8b via the high speed amplifier 7e. Next, when the LD ₄ is caused to emit light, the corresponding PD ₇ and PD ₈ receive the reflected light, and the light reception signal from the PD _{7 is} selected by the MUX 7c and is output to the comparator 8a via the high-speed amplifier 7d. . Further, the light reception signal from the PD _{8 is} selected by the MUX 7c and output to the comparator 8b through the high speed amplifier 7e.

Similarly, LD ₅ to LD ₈ emit light sequentially, and reflected light is sequentially received by two PDs corresponding to each LD, and light reception signals from each PD are sequentially selected by the MUX 7c, and a high-speed amplifier according to the PD. The data is output to the comparator 8a or 8b via 7d or 7e. Thereafter, the LD, PD, MUX 7c, and high-speed amplifiers 7d and 7e are operated again in the above order.

In one first scanning period, the control unit 1 drives the comparators 8a and 8b and the ADCs 9a and 9b to process the light reception signal output from the light reception module 7 as needed. At this time, the received light signals from PD ₁ , PD ₃ , PD ₅ , PD ₇ , PD ₉ , PD ₁₁ , PD ₁₃ , and PD ₁₅ are processed by the comparator 8 a and ADC 9 a, and PD ₂ , PD ₄ , PD ₆ , PD ₈ , PD ₁₀ , PD ₁₂ , PD ₁₄ , and PD ₁₆ process the received light signals in the comparator 8b and ADC 9b. The ADCs 9a and 9b operate intermittently in response to switching of selection of received light signals by the MUX 7c. (The same applies to the second scanning period described later.)

  In the first scanning period, the object detection unit 1a detects the presence / absence of the object 50 and the distance to the object 50 based on the light reception signal output from the ADC 9a or the ADC 9b as needed. The distance to the object 50 is calculated by the object detection unit 1a by the TOF method. Further, the presence direction of the target object 50 is also detected based on the output source PD of the light reception signal that has detected that the target object 50 is present.

  In the other first scanning period in which the laser beam from the LD group 2a is reflected by the other first reflecting surface 4b and scanned within a predetermined range, the LD, PD, and PD are performed in the same manner as in the first scanning period. , MUX 7c, high-speed amplifiers 7d and 7e, comparators 8a and 8b, ADCs 9a and 9b, and object detection unit 1a are operated.

  On the other hand, during the second scanning period in which the laser beam from the LD group 2a is reflected by the second reflecting surface 4c of the mirror 4a and scanned within a predetermined range by the rotary scanning unit 4, the object 50 (see FIG. 9 and FIG. This is a period for detecting the objects 50b, 50c, etc. in FIG.

Therefore, in the second scanning period (hereinafter referred to as “one second scanning period”) in which the laser beam from the LD group 2a is reflected by one second reflecting surface 4c and scanned within a predetermined range (hereinafter referred to as “one second scanning period”). As shown in FIG. 12, among the plurality of LD ₁ to LD ₈ , a specific LD ₄ is caused to emit light a plurality of times at a predetermined cycle. In FIG. 12, the LD ₄ emits light 16 times, but the number of times of light emission may be set as appropriate. Thereby, the laser beam is projected horizontally from the LD ₄ , and the laser beam is scanned in the horizontal direction within a predetermined range by the rotary scanning unit 4. After emitting the LD _4, then until causing again emitting the LD _4, the control unit 1 charges the capacitor 2c charges are discharged (Fig. 6).

Further, in one second scanning period, every time the LD ₄ emits light, the control unit 1 sequentially sets the plurality of PD ₁ to PD ₁₆ to the light receiving state two by two, and is output from the light receiving state PD ₁ to PD _16. The MUX 7c sequentially selects the received light signal. Specifically, the reflected light is received by the pair of PDs corresponding to each LD once in order, and the light receiving signals output from the two PDs in the light receiving state are sequentially selected by the MUX 7c, and then again. The two pairs of PDs receive the reflected light once in order, and the MUX 7c sequentially selects the received light signals output from the two PDs in the light receiving state.

Specifically, first, with respect to the _first light emission of the LD ₄ , the reflected light is received by the PD ₁ and PD ₂ , and the received light signal from the PD _{1 is} selected by the MUX 7c, and then via the high-speed amplifier 7d. The output is made to the comparator 8a. Further, the light reception signal from PD _{2 is} selected by MUX 7c and output to comparator 8b via high-speed amplifier 7e. Next, with respect to the second light emission of LD ₄ , PD ₃ and PD ₄ receive reflected light, and a light reception signal from PD _{3 is} selected by MUX 7c and output to comparator 8a via high-speed amplifier 7d. Let In addition, the light reception signal from the PD _{4 is} selected by the MUX 7c and output to the comparator 8b via the high-speed amplifier 7e. Next, with respect to the third light emission of the LD ₄ , the reflected light is received by the PD ₅ and PD ₆ , the received light signal from the PD _{5 is} selected by the MUX 7c, and output to the comparator 8a via the high-speed amplifier 7d. Let Further, the light reception signal from the PD _{6 is} selected by the MUX 7c and output to the comparator 8b via the high speed amplifier 7e. Next, with respect to the fourth light emission of LD ₄ , PD ₇ and PD ₈ receive reflected light, and a light reception signal from PD _{7 is} selected by MUX 7c, and output to comparator 8a via high-speed amplifier 7d. Let Further, the light reception signal from the PD _{8 is} selected by the MUX 7c and output to the comparator 8b through the high speed amplifier 7e.

Similarly, with respect to the fifth to eighth light emission of the LD ₄ , the reflected light is sequentially received by the two PDs, and the received light signals from the PDs are sequentially selected by the MUX 7c, and the high-speed amplifier according to the PD. The data is output to the comparator 8a or 8b via 7d or 7e. Thereafter, the LD, the PD, the MUX 7c, and the high-speed amplifiers 7d and 7e are operated again in the above order for the ninth and subsequent light emission of the LD ₄ .

  In one second scanning period, the control unit 1 drives the comparators 8a and 8b and the ADCs 9a and 9b to process the light reception signal output from the light reception module 7 as needed. And the object detection part 1a detects the presence or absence of the target object 50, or the distance to the target object 50 based on the light reception signal output at any time from ADC9a or ADC9b. The distance to the object 50 may be calculated by the object detection unit 1a by the TOF method, or based on the arrival angle of the reflected light from the object 50 and a predetermined arithmetic expression as shown in FIG. It may be calculated. Further, since the object 50 detected in the second scanning period is at a short distance, detection of the distance to the object 50 may be omitted.

  In the other second scanning period in which the laser beam from the LD group 2a is reflected by the other second reflecting surface 4c and scanned to a predetermined range, LD, PD, The MUX 7c, the high-speed amplifiers 7d and 7e, the comparators 8a and 8b, the ADCs 9a and 9b, and the object detection unit 1a are operated.

  According to the above embodiment, the laser light projected from one of the LDs and the reflected light from the object 50 of the laser light during the first scanning period are the first reflecting surface 4b of the mirror 4a of the rotary scanning unit 4. When the laser beam is reflected by the object 50 at a long distance, the reflected light from the object 50 enters the PD corresponding to the LD that has projected the laser light. For this reason, by causing the PD corresponding to the LD in the light emitting state to receive the reflected light, the object detection unit 1a can accurately detect the object 50 at a long distance based on the light reception signal output from the PD. Can do.

  Further, in the above embodiment, when the laser light projected from any LD is diffusely reflected by the second reflecting surface 4c of the mirror 4a of the rotary scanning unit 4 in the second scanning period, each laser is used. Light strikes the object 50 from different directions, and the reflected light of the laser light from the object 50 enters the plurality of PDs from different directions. Further, also when the reflected light from the object 50 is diffusely reflected by the second reflecting surface 4c, the reflected light enters the plurality of PDs from different directions. At this time, since the reflected light is incident on more PDs than the number of PDs corresponding to the LD in the light emitting state, even if the reflected light is reflected light from the object 50 at a short distance, the light is reflected in the LD in the light emitting state. The reflected light can be easily incident on the corresponding PD. For this reason, based on the light reception signal output from the PD, the object detection unit 1a can accurately detect the object 50 at a short distance.

  Moreover, in the above embodiment, the rotary scanning unit 4 reflects the laser light projected from the LD on the respective reflecting surfaces 4b and 4c of the mirror 4a and scans the laser beam on a predetermined range, and reflects the reflected light from the object 50. Each of the reflecting surfaces 4b and 4c is reflected and led to the PD. For this reason, the laser beam projected from the LD and the reflected light from the object 50 are projected and received while being scanned by the first reflecting surface 4b and the second reflecting surface 4c, thereby detecting the object 50 in a wide range. be able to. In addition, since the light projecting / receiving path is bent by the rotation scanning unit 4, the object detection device 100 can be downsized.

  In the above embodiment, the entire second reflection surface 4c of the mirror 4, that is, the incident portion of the laser light projected from the LD and the incident portion of the reflected light from the object 50 on the second reflection surface 4c. Is constituted by a diffuse reflection surface. For this reason, during the second scanning period, the laser light projected from the LD can be diffusely reflected by the second reflecting surface 4c, and each laser light can be projected from a different direction onto the object 50 within a predetermined range. Further, the reflected light of the laser beam on the object 50 can be incident on the second reflecting surface 4c from different directions, diffusely reflected by the second reflecting surface 4c, and incident on a large number of PDs. Even when the laser light is reflected by the object 50 at a short distance, the reflected light can be incident on the PD corresponding to the LD on which the laser light is projected. As a result, the object 50 at a short distance can be detected with higher accuracy by the object detection unit 1a based on the light reception signal output from the PD corresponding to the LD projecting the laser beam.

  Moreover, in the above embodiment, the light receiving signal output from the light receiving PD among the plurality of PDs is selected by the MUX 7c as the light receiving signal for detecting the object. Therefore, during the first scanning period and the second scanning period, a light reception signal output from the PD that receives the reflected light from the target 50 is input from the MUX 7c to the object detection unit 1a, and the object detection unit 1a receives the light reception signal. The object 50 at a long distance or a short distance can be detected with higher accuracy based on the signal.

In the above embodiment, the width W2 of the second reflecting surface 4c parallel to the scanning surface by the rotational scanning unit 4 of the laser light projected from the LD is the first reflecting surface parallel to the scanning surface. It is narrower than the width W1 of 4b. For this reason, in the second scanning period, a time for scanning a laser beam projected from a specific LD ₄ within a predetermined range, a time for sequentially switching a plurality of PDs, and a time for sequentially switching light reception signals output from the PDs by the MUX 7c. It can be shortened. Then, by resting the LD, PD, MUX 7c, comparators 8a and 8b, ADCs 9a and 9b, or the object detection unit 1a for the shortened time, the burden of these operations or processes can be reduced.

  Moreover, in the above embodiment, the mirror 4a of the rotation scanning unit 4 is formed in a plate shape, the first reflecting surfaces 4b are provided on both plate surfaces of the mirror 4a, and both side surfaces having a smaller area than the mirror 4a plate surface. The second reflecting surface 4c is provided. For this reason, the area of the 2nd reflective surface 4c can be made smaller than the area of the 1st reflective surface 4b, and a 2nd scanning period can be shortened further from a 1st scanning period. Then, the LD, PD, MUX 7c, comparators 8a and 8b, ADCs 9a and 9b, and the object detection unit 1a can be suspended to further reduce the burden of these operations or processes.

  Further, in the above embodiment, the plurality of LDs are arranged so as to be aligned vertically (up and down) with respect to the scanning surface of the laser beam by the rotary scanning unit 4. For this reason, the laser beam can be scanned not only in the horizontal direction but also in the vertical direction, and the detection accuracy of the object 50 can be further improved.

  Further, in the above embodiment, laser light is sequentially projected from a plurality of LDs in the first scanning period, and the laser light is specularly reflected by the first reflecting surface 4b and scanned within a predetermined range. Reflected light from the object 50 is received by the PD corresponding to the above. For this reason, when the laser beam projected from any LD is reflected by the object 50 at a long distance, the reflected light can be reliably received by the PD corresponding to the LD. Then, based on the light reception signal output from the PD, the object detection unit 1a can detect the object 50 at a long distance with higher accuracy.

In the above embodiment, in the second scanning period, laser light is projected from the specific LD _{4 at a} predetermined period, and the laser light is diffusely reflected by the second reflecting surface 4c and scanned within a predetermined range. Reflected light from the object 50 is sequentially received by a plurality of PDs. For this reason, even if the laser light projected from the specific LD ₄ is reflected by the object 50 at a short distance, the reflected light from the object 50 can be searched for by a plurality of PDs. And based on the light reception signal output from each PD, it becomes possible to detect the target object 50 in the short distance by the object detection part 1a with higher accuracy.

  Furthermore, in the above embodiment, the object 50 detected based on the light reception signal output from the light receiving module 7 in the first scanning period is regarded as being at a long distance, and not only the presence / absence of the object 50 is detected. The trend of the object 50 can be tracked by detecting the distance to the object 50 and the direction in which the object 50 exists by the object detection unit 1a. Further, in the second scanning period, the object detection unit 50 detects that the object 50 detected based on the light reception signal output from the light reception module 7 is at a short distance, and detects only the presence or absence of the object 50, thereby detecting the object detection unit. The processing load of 1a can be reduced.

  The present invention can employ various embodiments other than those described above. For example, in the above embodiment, an example is shown in which an LD is used as a light emitting element and a PD is used as a light receiving element, but the present invention is not limited to these. An appropriate number of light emitting elements other than the LD may be provided in the light emitting module 2. Further, for example, an appropriate number of light receiving elements other than the PIN type PD such as APD (Avalanche Photo Diode) may be provided in the light receiving module 7. In addition, one or more SPAD (Single Photon Avalanche Diode), which is an APD in Geiger mode, or MPPC (Multi-Pixel Photon Counter), which is composed of a plurality of SPADs connected in parallel, is provided in the light receiving module 7 as a light receiving element. Also good. Furthermore, the arrangement of a plurality of light emitting elements and a plurality of light receiving elements may be set as appropriate.

  In the above embodiment, an example in which a pair of two PDs is associated with each of a plurality of LDs has been described, but the present invention is not limited to this. In addition to this, for example, one or three or more PDs may be associated with each of a plurality of LDs. Further, the number of PDs corresponding to each LD may be the same or different. In the first scanning period, the light emission order of the plurality of LDs, the light reception order of the plurality of PDs, or the selection order of the light reception signals may be set as appropriate. In the second scanning period, the light emitting LD, the light receiving order of the plurality of PDs, or the light receiving signal selection order may be set as appropriate.

In the embodiment shown in FIG. 12, in order to more reliably receive the reflected light from the object 50 at a short distance in the second scanning period, the reflected light is sequentially received by all the PD ₁ to PD _16. Although an example is shown, the present invention is not limited to this. In consideration of the diffuse reflection state of the second reflecting surface 4c, the PD that receives the reflected light in the second scanning period may be only the PD corresponding to the LD in the light emitting state, or only a part of the PD.

Moreover, although the above embodiment showed the example which comprised the whole surface of the 2nd reflective surface 4c of the mirror 4a of the rotation scanning part 4 with the diffuse reflection surface, this invention is not limited only to this. In addition to this, for example, as shown in FIG. 13, the lower half region 4c ₁ of the second reflecting surface 4c of the mirror 4a, that is, the incident portion 4c ₁ of the laser light projected from the LD is formed of a diffuse reflecting surface, The upper half region 4c ₂ of the two reflecting surfaces 4c, that is, the incident portion 4c ₂ of the reflected light from the object 50 may be configured as a specular reflecting surface. Conversely, as shown in FIG. 14, the region 4c ₁ of the lower half of the second reflecting surface 4c of the mirror 4a constituted by specular surface, diffuse reflection surface areas 4c ₂ of the upper half of the second reflecting surface 4c You may comprise. That is, at least one of the incident part of the laser beam and the incident part of the reflected light on the second reflecting surface 4c of the mirror 4a may be configured by a diffuse reflecting surface.

  Moreover, in the above embodiment, the example which provided the 1st reflective surface 4b in the both board surfaces with a large area of the plate-shaped mirror 4a of the rotation scanning part 4, and provided the 2nd reflective surface 4c in the both sides | surfaces with a small area. Although shown, the present invention is not limited to this. In addition to this, for example, one of the two plate surfaces of the plate-like mirror 4a may be provided with the first reflection surface, and the other may be provided with the second reflection surface. Further, a rotary scanning unit having a mirror such as a polygon mirror having three or more side surfaces as reflection surfaces, or a rotation scanning unit having a mirror of another shape provided with a plurality of reflection surfaces may be used. . One of the plurality of reflecting surfaces of the mirror may be a first reflecting surface made of a specular reflecting surface, and the other may be a second reflecting surface including a diffuse reflecting surface. Further, the number of the first reflecting surface and the second reflecting surface may be one each, or two or more. The area of the first reflecting surface and the area of the second reflecting surface may be different or the same. Further, for example, the laser beam from the LD is scanned within a predetermined range by the rotary scanning unit, but the reflected light from the object in the predetermined range is rotated so as to be received by the light receiving element without passing through the rotary scanning unit. You may design the shape of a scanning part, or may arrange | position a rotation scanning part and a light receiving element. In this case, the incident portion of the laser beam on the second reflection surface of the mirror of the rotary scanning unit may be configured with a diffuse reflection surface.

  In the above embodiment, an example in which the MUX 7c is provided in the light receiving module 7 as a signal selection unit that selects light reception signals output from a plurality of PDs has been described. However, the present invention is not limited to this. . A signal selection unit other than the MUX may be provided in the light receiving module 7. The signal selection unit may be provided outside the light receiving module 7.

  In the above embodiment, the voltage signal is output from the light receiving module 7 as the light receiving signal and processed in the subsequent stage. However, the present invention is not limited to this. In addition to this, for example, a current signal corresponding to the output current from each light receiving element is output as a light receiving signal from the light receiving module and processed by a comparator, ADC, or control unit in the subsequent stage, and the presence or absence of the object or the object The distance may be detected.

  Further, in the above embodiment, the example in which the present invention is applied to the object detection apparatus 100 including the on-vehicle laser radar has been described. However, the present invention is also applied to the object detection apparatus for other uses. It is possible.

DESCRIPTION OF SYMBOLS 4 Rotation scanning part 4a Mirror 4b 1st reflective surface 4c 2nd reflective surface 4c ₁ Incident part of the laser beam in the 2nd reflective surface 4c ₂ Incident part of the reflected light in the 2nd reflective surface 7c MUX (signal selection part)
50, 50a, 50b, 50c Object 100 Object detection device LD, LD _{1 to} LD ₈ Light emitting element LD ₄ Specific light emitting element PD, PD _{1 to} PD ₁₆ Light receiving element Z Scanning angle range (predetermined range)
W1 Width of the first reflecting surface W2 Width of the second reflecting surface

Claims (8)

A plurality of light emitting elements that project light;
A plurality of light receiving elements that receive light and output a light reception signal;
A mirror is included, and the projection light projected from the light emitting element is reflected by the mirror and scanned in a predetermined range by rotating the mirror, and the reflected light of the projection light from the object in the predetermined range A rotation scanning unit that reflects the light from the mirror and guides the light to the light receiving element,
The light emitting elements to be emitted are sequentially switched, the projection light from the light emitting elements in the light emitting state is scanned to a predetermined range by the rotary scanning unit, and the reflected light is received corresponding to the light emitting elements in the light emitting state. In the object detection device that detects the object based on a light reception signal output from the light receiving element in a light receiving state by sequentially switching light receiving elements.
The mirror has a first reflection surface and a second reflection surface that reflect light without belonging to the same plane,
The first reflecting surface is a specular reflecting surface,
2. The object detection apparatus according to claim 1, wherein the second reflection surface includes a diffuse reflection surface. The object detection apparatus according to claim 1,
The rotational scanning unit
The projected light is reflected by the reflecting surfaces of the mirror and scanned to a predetermined range, and the reflected light is reflected by the reflecting surfaces and led to the light receiving element,
An object detection apparatus, wherein an incident portion of the projection light or an incident portion of the reflected light on the second reflection surface is formed of the diffuse reflection surface. In the object detection apparatus according to claim 1 or 2,
The object of the present invention is characterized in that a width of the second reflecting surface parallel to the scanning surface of the projection light by the rotary scanning unit is narrower than a width of the first reflecting surface parallel to the scanning surface. Detection device. The object detection apparatus according to any one of claims 1 to 3,
The mirror is formed in a plate shape,
The first reflecting surface is provided on the plate surface of the mirror;
2. The object detection apparatus according to claim 1, wherein the second reflection surface is provided on a side surface having a smaller area than the plate surface of the mirror. The object detection device according to any one of claims 1 to 4,
The object detection apparatus according to claim 1, wherein the diffuse reflection surface has a mirror shape that diffusely reflects incident light. In the target object detection device according to any one of claims 1 to 5,
The object detection further comprising a signal selection unit that selects the light reception signal output from the light reception element in the light reception state among the plurality of light reception elements as the light reception signal for the object detection. apparatus. The object detection device according to any one of claims 1 to 6,
The plurality of light emitting elements are arranged so as to be aligned perpendicular to a scanning surface of the projection light by the rotation scanning unit,
In the first scanning period in which the rotational scanning unit reflects the projection light by the first reflecting surface and scans the predetermined range.
Sequentially emitting the plurality of light emitting elements, sequentially causing the light receiving elements corresponding to the light emitting elements in the light emitting state to receive the reflected light,
In the second scanning period in which the rotational scanning unit reflects the projection light by the second reflecting surface and scans the predetermined range,
An object detection apparatus, wherein a specific light-emitting element among the plurality of light-emitting elements is caused to emit light at a predetermined cycle, and the reflected light is sequentially received by the plurality of light-receiving elements. The object detection device according to claim 7,
In the first scanning period, based on the light emission state of the light emitting element and the light reception signal, the presence / absence of the object, the presence direction of the object, or the distance to the object is detected,
In the second scanning period, at least the presence / absence of the object is detected based on the light emitting state of the light emitting element and the light reception signal.

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