JP2019020149A - Target detection apparatus - Google Patents

Abstract

To improve both detection accuracy of a target and diagnostic accuracy of an optical system failure.SOLUTION: A target detection apparatus 100 includes a light emitting module 2, a rotation scanning unit for scanning projection light from the light emitting module 2 in a predetermined range, a light receiving module 7 for receiving the projection light and reflected light from a target, a target detection unit 1a for detecting the target based on a light receiving signal output from the light receiving module 7 during a scanning period (target detection period) of laser light to the predetermined range, a light guide for guiding the projection light to the light receiving module 7 during a specific period (failure diagnostic period) when the projection light travels to a specific direction outside of the predetermined range, a failure diagnosis unit 1b for diagnosing the presence or absence of a failure based on the light receiving signal output from the light receiving module 7 in the specific period, a signal multiplication unit 9 for setting a multiplication factor of the light receiving signal to make the light receiving unit 7 output a light receiving signal with a level in response to the multiplication factor, and a multiplication control unit 1c for making the multiplication factor of the light receiving signal for the specific period larger than the multiplication factor of the light receiving signal for the scanning period.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an object detection apparatus that detects an object by projecting light from a light emitting unit and receiving reflected light by a light receiving unit, and more particularly to self-diagnosis of an optical system failure.

  For example, an object detection device such as a laser radar is mounted on a vehicle having a collision prevention function. The object detection device projects light from the light emitting unit and detects the presence or absence of the object and the distance to the object based on the result of receiving the reflected light by the light receiving unit.

  A light emitting element such as a laser diode is used as the light emitting part, and a light receiving element such as a photodiode or an avalanche photodiode is used as the light receiving part.

  There are also object detection devices having a function of scanning light in order to project and receive light over a wide range or to downsize the device (for example, Patent Documents 1 to 7). In Patent Documents 1, 2, 4, 6, and 7, light is scanned over a predetermined range by a rotary scanning unit having a rotatable mirror. As the mirror, a polygon mirror is used in Patent Document 1. In Patent Document 2, a concave mirror is used. In Patent Documents 4 and 7, a plate-like mirror is used. In Patent Document 6, a quadrangular prism-shaped polygonal mirror is used.

  In the light projecting / receiving path for detecting an object, first, the light projected from the light emitting element of the light emitting unit is reflected by the mirror of the rotary scanning unit after passing through a light projecting optical component such as a light projecting lens or a mirror. And projected onto a predetermined range for detecting the object. At this time, the mirror of the rotary scanning unit rotates, so that the light from the light emitting element is deflected by the mirror and scanned within a predetermined range.

  And when the light projected on the predetermined range is reflected by the target object, for example, in Patent Documents 1 and 4, the reflected light is received by the light receiving element of the light receiving unit. Further, in Patent Documents 2, 6, and 7, for example, the reflected light is reflected by a mirror of a rotational scanning unit, passes through other optical components of a light receiving system such as another mirror and a light receiving lens, and then received by a light receiving element of the light receiving unit. Received light. Also at this time, when the mirror of the rotary scanning unit rotates, the reflected light is deflected by the mirror and guided to the light receiving unit.

  If the optical system is broken, the presence or absence of the object and the distance to the object cannot be accurately detected. Therefore, a function for self-diagnosis of an optical system failure in the object detection apparatus has been proposed.

  For example, in Patent Literatures 1, 4, and 5, a light projecting / receiving path or a light guide unit for failure diagnosis is provided inside the object detection device, and the light from the light emitting unit is guided to the light receiving unit.

  Specifically, in Patent Document 1, the inside of the apparatus is divided into a light emitting side space and a light receiving side space by a partition wall, and a hole is formed in a part of the partition wall. Then, the light from the light emitting part is reflected in a specific direction by the reflecting surface of the polygon mirror so that the light is reflected by the window plate installed at the front part of the apparatus through the hole in the partition wall and led to the light receiving part. Yes.

  In Patent Document 4, light from a light emitting unit is reflected by a scan mirror in a specific direction and guided to a light receiving unit for self-diagnosis. In Patent Document 5, light that travels in a specific direction outside the scanning angle range out of light from the light emitting unit is reflected by the inner surface of a translucent window plate installed in the front part of the apparatus, and is used for object detection. It leads to the light receiving part or the light receiving part for self-diagnosis.

  And in patent documents 1, 4, and 5, when the light from a light emission part advances to the specific direction out of a scanning range, the presence or absence of a failure of a light emission part or a light reception part based on the electrical signal output from a light reception part Is detected.

  On the other hand, in Patent Documents 2 and 3, in order to improve the detection accuracy of the distance to the object, the light from the light emitting part is guided to the light receiving part by the light guiding part provided inside the object detecting device.

  Specifically, in Patent Document 2, an optical fiber light introducing portion is disposed on the optical axis of light traveling from the light emitting portion to the object side via the mirror of the rotational scanning portion, and the light is taken in from the light introducing portion. In this case, the light is guided to the light receiving portion by an optical fiber. Further, in Patent Document 3, light from the light emitting unit is reflected by a reference reflector disposed at the end of the scanning range and guided to the light receiving unit.

  And in patent document 2 and 3, the correction value is calculated based on the electric signal output from a light-receiving part at the time of correction | amendment, etc., and the distance to the detected target object is correct | amended with the correction value.

JP 2002-31685 A JP 2010-204015 A JP 2012-93256 A Japanese Patent Laid-Open No. 9-318736 Japanese Patent Laid-Open No. 10-31064 JP 2014-145744 A International Publication WO2016 / 012579

  In order to diagnose the presence or absence of a failure in the optical system, it is necessary to provide a failure diagnosis light projecting / receiving path provided with a light guide unit inside the object detection device. However, if the light projected toward the object enters the light guide part of the light projecting / receiving path for failure diagnosis when the object is detected, this light becomes stray light and is guided to the light receiving part. And the detection accuracy of the distance to the object may be lowered. In order to suppress this stray light, it is effective to reduce the amount of light passing through the light projecting / receiving path for failure diagnosis by reducing the light transmittance of the light guide unit, etc. The level of the light reception signal output from the light receiving unit is lowered, and the diagnosis accuracy of the presence or absence of a failure is lowered.

  It is an object of the present invention to provide an object detection apparatus that can improve both the detection accuracy of an object and the diagnosis accuracy of a failure in an optical system.

  An object detection apparatus according to the present invention includes a light emitting unit having a light emitting element, a mirror, and a rotating scanning unit that scans a predetermined range by reflecting the projection light from the light emitting unit by rotating the mirror. And a light receiving unit having a light receiving element that receives projection light or reflected light from an object within a predetermined range of the projection light, and light reception by the light receiving element during a scanning period in which the projection light is scanned to the predetermined range by the rotary scanning unit. Based on the light reception signal output from the light receiving unit according to the state, the object detection unit that detects the target object and the projection light is guided to the light receiving unit during a specific period in which the projection light travels in a specific direction outside a predetermined range. Based on a light guide unit, a light receiving signal output from the light receiving unit during a specific period, a failure diagnosing unit for diagnosing the presence or absence of a failure, and a light receiving signal at a level corresponding to the multiplication factor by setting a multiplication factor of the light receiving signal Is output from the light receiver, and And a multiplication control unit for controlling the multiplication factor of. The multiplication control unit makes the multiplication factor of the received light signal in the specific period larger than the multiplication factor of the received light signal in the scanning period.

  According to the above, in the scanning period (object detection period) in which the projection light from the light emitting unit is scanned to a predetermined range by the mirror of the rotary scanning unit, the projection light is not guided to the light receiving unit by the light guide unit, and the projection light is predetermined. During a specific period (failure diagnosis period) that travels in a specific direction outside the range, the projection light is guided to the light receiving unit by the light guide unit, and based on the light reception signal output from the light receiving unit, the fault diagnosis unit The presence or absence of a failure is diagnosed. For this reason, the amount of light passing through the light projecting / receiving path for failure diagnosis is made smaller than the amount of light passing through the light projecting / receiving path for detecting the object, so that stray light at the time of detecting the object in the light guide unit is reduced. It is possible to improve the accuracy of detection of the presence / absence of the object and the distance to the object by the detection unit.

  In addition, since the multiplication factor of the light reception signal in the specific period (fault diagnosis period) is made larger than the multiplication factor of the light reception signal in the scanning period (object detection period), the level of the light reception signal is increased during the specific period to diagnose the fault. It is possible to improve the diagnostic accuracy of the presence or absence of failure of the optical system by the unit. Furthermore, since the multiplication factor of the light reception signal is not increased to the same level as that of the specific period during the scanning period, it is possible to prevent the level of noise included in the light reception signal from the light receiving unit from increasing during the scanning period. For this reason, it becomes possible to distinguish noise and a reflected light signal correctly, and to suppress that the detection accuracy of the presence or absence of a target object or the distance to a target object falls.

  In the present invention, a transmission window that transmits the projection light and the reflected light from the object of the projection light is provided between the rotary scanning unit and the predetermined range (scanning range), and the light transmittance of the light guide unit is transmitted. You may make it lower than the light transmittance of a window.

  In the present invention, the light receiving element includes an APD (Avalanche Photo Diode), the signal multiplication unit includes a reverse voltage generation unit that generates a reverse voltage and applies the reverse voltage to the APD, and the multiplication control unit The multiplication factor of the received light signal may be changed by changing the reverse voltage applied to the APD by the voltage generator.

  Further, in the present invention, the scanning period is longer than the specific period, and the rotary scanning unit reflects the reflected light with a mirror and guides it to the light receiving unit during the scanning period, and transmits disturbance light from the outside of the target object detection device during the specific period. It may not be guided to the light receiving unit by a mirror.

  Furthermore, in the present invention, the light guide unit may not guide disturbance light from the outside of the object detection device to the light receiving unit.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the target object detection apparatus which can improve both the detection accuracy of a target object, and the diagnostic accuracy of the failure of an optical system.

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 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 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 the figure which showed the electrical structure of the target object detection apparatus of FIG. It is the figure which showed the relationship between the reverse voltage of APD and a multiplication factor. It is the figure which showed the relationship between the multiplication factor of APD and an output. It is the figure which showed the operation | movement timing of the target object detection apparatus of FIG. It is the figure which showed the output signal at the time of the target object detection of the light reception module of FIG. It is the figure which showed the output signal at the time of failure diagnosis of the light reception module of FIG. It is the figure which showed the output signal at the time of failure diagnosis of the conventional light reception module. It is the figure which showed the electrical structure of the target object detection apparatus by other embodiment of this invention. It is the figure which showed the electrical structure of the target object detection apparatus 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.

  1A and 1B are diagrams illustrating a state in which the optical system of the object detection apparatus 100 according to the embodiment is viewed from above. 2A and 2B are diagrams illustrating a state in which the optical system of the object detection device 100 is viewed from the rear (lower side in FIGS. 1A and 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) 2a, a light projecting lens 14, a rotation scanning unit 4, a transmission window 20, a light guide 15, a light receiving lens 16, a reflecting mirror 17, and an APD (Avalanche Photo Diode). 7a.

  Among them, the LD 2a, the light projecting lens 14, the rotation scanning unit 4, and the transmission window 20 are a light projecting optical system. The transmission window 20, the rotation scanning unit 4, the light receiving lens 16, the reflecting mirror 17, and the APD 7a are a light receiving optical system. The light guide 15 is a light guide component for failure diagnosis of the optical system LD 2a, the rotary scanning unit 4, or the APD 7a.

  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.

  The LD 2a is a light emitting element that projects high-power laser light (light pulse). 1A to 2B, only one LD 2a is shown for convenience, but a plurality of LDs 2a are actually arranged in the vertical direction in FIGS. 2A and 2B. The LD 2a is arranged so that the light emitting surface faces the rotation scanning unit 4 side.

  The APD 7a is a light receiving element that receives laser light (projection light) projected from the LD 2a, light reflected by the object 50 of the laser light, and the like. In FIG. 1A to FIG. 2B, only one APD 7a is shown for convenience, but a plurality of APDs 7a are actually arranged in an array in the vertical direction or the horizontal direction in FIGS. 2A and 2B. The APD 7a is arranged so that the light receiving surface faces the reflecting mirror 17 side.

  The rotary scanning unit 4 is also called a rotary mirror or an optical deflector. The rotary scanning unit 4 includes a mirror 4a and a motor 4c. The mirror 4a is formed in a plate shape. The front and back surfaces of the mirror 4a are reflective surfaces.

  As shown in FIGS. 2A and 2B, a motor 4c is provided below the mirror 4a. The rotation shaft 4j of the motor 4c is parallel to the vertical direction. A connecting shaft (not shown) at the center of the mirror 4a is fixed to the upper end of the rotating shaft 4j of the motor 4c. The mirror 4a rotates in conjunction with the rotation shaft 4j of the motor 4c.

  In the case 19, the light receiving lens 16, the reflecting mirror 17, and the APD 7 a are arranged around the upper part of the mirror 4 a of the rotary scanning unit 4. The LD 2a and the light projecting lens 14 are arranged around the lower part of the mirror 4a. A light shielding plate 18 is provided above the LD 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 guide 15 is formed of a material having a light guide property. The light guide 15 is disposed in the case 19 of the object detection apparatus 100 on the opposite side of the LD 2a, the APD 7a, the lenses 14 and 16, and the reflecting mirror 17 with respect to the mirror 4a of the rotational scanning unit 4. Moreover, the light guide 15 is arrange | positioned with respect to the mirror 4a and the transmission window 20 on the opposite side to the target object 50, as shown to FIG. 1A and FIG. 1B.

  As shown in FIGS. 2A and 2B, the light guide 15 is provided with an introduction surface 15a for introducing light and a lead-out surface 15b for guiding light. The light guide 15 is fixed in the case 19 so that the introduction surface 15a and the lead-out surface 15b face the mirror 4a side of the rotary scanning unit 4. The introduction surface 15a and the lead-out surface 15b are arranged in the vertical direction. The lead-out surface 15b is disposed above the introduction surface 15a.

  The light guide 15 introduces the laser light projected from the LD 2a from the introduction surface 15a via the rotary scanning unit 4 and the like, transmits the laser light to the inside, and then derives it from the lead-out surface 15b for rotational scanning. Guide to the APD 7a via the part 4 and the like. The light transmittance of the light guide 15 is lower than the light transmittance of the transmission window 20. The light guide 15 is an example of the “light guide” in the present invention.

  The light projecting / receiving path when detecting the object 50 is as shown by the one-dot chain line and two-dot chain arrow in FIGS. 1A and 2A. Specifically, as indicated by the one-dot chain line arrows in FIGS. 1A and 2A, the laser light projected from the LD 2a is adjusted for spread by the light projecting lens 14, and then the mirror 4a of the rotary scanning unit 4 is adjusted. Hits the lower half of the front or back side. At this time, the motor 4c rotates to change the angle (orientation) of the mirror 4a so that the front or back surface of the mirror 4a becomes a predetermined angle facing the object 50 (for example, the mirror 4a shown by a solid line in FIG. 1A). State). Thus, after the laser light from the LD 2a is transmitted through the light projecting lens 14, it is reflected by the lower half region of the front or back surface of the mirror 4a, is transmitted through the transmission window 20, and is scanned within a predetermined range outside the case 19. The That is, the rotary scanning unit 4 deflects the laser beam from the LD 2a to a predetermined range.

  A scanning angle range Z shown in FIG. 1A is a predetermined range (viewed from above) in which the laser light from the LD 2a is reflected by the front or back surface of the mirror 4a of the rotary scanning unit 4 and projected from the object detection device 100. That is, the scanning angle range Z is a detection range of the object 50 by the object detection device 100.

  As described above, the laser light projected from the object detection apparatus 100 to the predetermined range is reflected by the object 50 in the predetermined range. The reflected light passes through the transmission window 20 and hits the upper half area of the front surface or the back surface of the mirror 4a as shown by the two-dot chain line arrows in FIGS. 1A and 2A. At this time, the motor 4c rotates to change the angle (orientation) of the mirror 4a so that the front or back surface of the mirror 4a becomes a predetermined angle facing the object 50 (for example, the mirror 4a shown by a solid line in FIG. 1A). State). Thereby, the reflected light from the object 50 is reflected by the upper half region of the front surface or the back surface of the mirror 4 a and enters the light receiving lens 16. That is, the rotary scanning unit 4 deflects the reflected light from the object 50 toward the light receiving lens 16 side. Then, the reflected light is collected by the light receiving lens 16, reflected by the reflecting mirror 17, and received by the APD 7a. That is, the rotary scanning unit 4 guides the reflected light from the object 50 to the APD 7a through the light receiving lens 16 and the reflecting mirror 17.

  The light projecting / receiving path for diagnosing a failure of the optical system is as shown by the one-dot chain line, the two-dot chain line, and the dashed arrow in FIGS. 1B and 2B. Specifically, as indicated by the one-dot chain line arrows in FIGS. 1B and 2B, the laser light projected from the LD 2 a is adjusted for spreading by the light projecting lens 14, and then the mirror 4 a of the rotary scanning unit 4 Hits the lower half of the front or back side. At this time, the motor 4c rotates to change the angle (orientation) of the mirror 4a so that the front or back surface of the mirror 4a becomes a predetermined angle facing the opposite side of the object 50 (for example, a mirror indicated by a solid line in FIG. 1B). 4a state). Thus, after the laser light from the LD 2a is transmitted through the light projecting lens 14, it is reflected by the lower half region of the front or back surface of the mirror 4a and travels in a specific direction in the case 19 opposite to the transmission window 20. . That is, the rotary scanning unit 4 deflects the laser light from the LD 2 a in a specific direction opposite to the object 50.

  As described above, the laser light traveling in a specific direction in the case 19 enters the light guide 15 from the introduction surface 15a in the specific direction. Then, the laser light passes through the inside of the light guide 15 as indicated by a broken line arrow in FIG. 2B, and is emitted from the lead-out surface 15b as indicated by a two-dot chain line arrow in FIGS. 1B and 2B. It hits the upper half area of the front or back surface of the mirror 4a. At this time, the motor 4c rotates to change the angle (orientation) of the mirror 4a so that the front or back surface of the mirror 4a becomes a predetermined angle facing the opposite side of the object 50 (for example, a mirror indicated by a solid line in FIG. 1B). 4a state). As a result, the light emitted from the light guide 15 is reflected by the upper half region of the front or back surface of the mirror 4 a and enters the light receiving lens 16. That is, the rotation scanning unit 4 deflects the light emitted from the light guide 15 toward the light receiving lens 16. The emitted light is collected by the light receiving lens 16, reflected by the reflecting mirror 17, and received by the APD 7a. That is, the rotary scanning unit 4 guides the light emitted from the light guide 15 to the APD 7 a through the light receiving lens 16 and the reflecting mirror 17.

The angle range of the mirror 4a incident on the light guide 15 from the angle range (θ ₁ , θ ₅ in FIG. 6 described later) of the mirror 4a in which the laser beam from the LD 2a is scanned to a predetermined range by the rotary scanning unit 4 ( theta ₃₎ of FIG. 6 to be described later is small (see FIG. 6 described later). Further, the light transmittance of the light guide 15 is lower than the light transmittance of the transmission window 20. For this reason, the amount of light passing through the failure diagnosing light emitting and receiving path shown in FIGS. 1B and 2B is smaller than the amount of light passing through the object detecting light projecting and receiving path shown in FIGS. 1A and 2A. .

  As shown in FIGS. 1A and 1B, the mirror 4a of the rotary scanning unit 4 has a plate shape. The light guide 15 is disposed in the inner part of the case 19 on the opposite side of the transmission window 20 with respect to the mirror 4a. For this reason, as shown in FIG. 1B and the like, when the laser light from the LD 2a enters the light guide 15 in a specific direction in the case 19, disturbance light that enters the transmission window 20 from the outside of the object detection device 100 (Sunlight or the like) is not guided to the light guide 15 or the APD 7a by the mirror 4a. In addition, disturbance light is not always guided to the APD 7 a by the light guide 15.

  FIG. 3 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 drive circuit 3, a motor 4 c, a motor drive circuit 5, an encoder 6, a light receiving module 7, an ADC (Analog to Digital Converter) 8, and a signal multiplication unit 9. A storage unit 11 and an interface 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, a failure diagnosis unit 1b, and a multiplication control unit 1c.

  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, information for diagnosing a failure, and the like.

  The interface 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 interface 12.

  The light emitting module 2 is provided with the plurality of LDs 2a described above and a capacitor 2c for causing each LD 2a to emit light. In FIG. 3, for the sake of convenience, one block of the LD 2a and one capacitor 2c is shown. The light emitting module 2 is an example of the “light emitting unit” in the present invention.

  The controller 1 controls the operation of the LD 2 a of the light emitting module 2 by the LD driving circuit 3. Specifically, the control unit 1 causes the LD drive circuit 3 to emit light from the LD 2a and projects laser light. In addition, the control unit 1 stops the light emission of the LD 2a by the LD drive circuit 3, and charges the capacitor 2c.

  The motor 4 c 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 4c by the motor drive circuit 5 to rotate the mirror 4a. Then, as described above, the control unit 1 rotates the mirror 4a to scan the laser light projected from the LD 2a within a predetermined range, and guides the reflected light reflected by the object 50 within the predetermined range to the APD 7a. . Further, as described above, the control unit 1 rotates the mirror 4a to guide the laser light projected from the LD 2a to the light guide 15 and guide the emitted light from the light guide 15 to the APD 7a. At these times, the control unit 1 detects the rotation state (rotation angle, rotation number, etc.) of the motor 4c and the mirror 4a based on the output of the encoder 6.

  The light receiving module 7 includes an APD 7a, a TIA (Trans Impedance Amplifier) 7b, a MUX (Multiplexer) 7c, and a constant current circuit 7d. The light receiving module 7 is an example of the “light receiving unit” in the present invention.

  A plurality of APDs 7a, TIAs 7b, and constant current circuits 7d are provided so as to form a pair. In FIG. 3, one set of APD 7a, TIA 7b, and constant current circuit 7d is representatively shown. However, the second and higher sets of APD 7a, TIA 7b, and constant current circuit 7d are also provided. Each set of APD 7a and TIA 7b constitutes a light receiving channel. That is, the light receiving module 7 is provided with a plurality of light receiving channels.

  The cathode of the APD 7a is connected to the power source + V through the constant current circuit 7d. The input terminal of the TIA 7b is connected between the cathode of the APD 7a and the constant current circuit 7d. The output terminal of the TIA 7b is connected to the MUX 7c. The anode of the APD 7 a is connected to the reverse voltage generation unit 9 a of the signal multiplication unit 9.

  The APD 7a outputs current by receiving light. The TIA 7b converts the current flowing through the APD 7a into a voltage signal and outputs it to the MUX 7c. In order to suppress the power consumption of the APD 7a, the constant current circuit 7d limits the current flowing through the APD 7a.

  The signal multiplier 9 includes a reverse voltage generator 9a and a reference voltage generator 9b. The reverse voltage generation unit 9a is composed of a DC-DC converter. The reference voltage generation unit 9b includes a PWM (pulse width modulation) circuit that generates a reference voltage to be input to the reverse voltage generation unit 9a. The reference voltage generation unit 9b generates a reference voltage by PWM and inputs it to the reverse voltage generation unit 9a. Then, the reverse voltage generator 9a generates a reverse voltage (reverse bias voltage) based on the reference voltage and applies it to the APD 7a. Thereby, the current output from the APD 7a at the time of light reception is multiplied.

  The MUX 7c selects the output signal of each TIA 7b and outputs it to the ADC 8. The ADC 8 converts the analog signal output from the MUX 7 c into a digital signal at high speed and outputs the digital signal to the control unit 1. That is, a voltage signal corresponding to the light receiving state of each APD 7 a is output from the light receiving module 7 to the control unit 1 via the ADC 8.

  The object detection unit 1a of the control unit 1 processes an output signal from the ADC 8 during a scanning period (θ1 and θ5 in FIG. 6) to be described later, and a feature point (maximum value) of the light reception signal from the light reception module 7 at a predetermined time. Etc.). Based on the feature points, the presence / absence of the object 50 and the distance to the object 50 are detected.

  Specifically, for example, the object detection unit 1a compares a light reception signal output from the light reception module 7 via the ADC 8 with a predetermined threshold value. If the light reception signal is equal to or greater than the threshold value, it is determined that the object 50 exists, and if the light reception signal is less than the threshold value, it is determined that there is no object 50. For example, the object detection unit 1a detects the maximum value of the received light signal that is equal to or greater than the threshold value, and detects the light reception time of the reflected light from the object 50 based on the maximum value. Then, the distance to the object 50 is calculated based on the light reception time of the reflected light and the projection time of the laser light from the LD 2a (so-called TOF (Time of Flight) method).

  The failure diagnosis unit 1b processes an output signal from the ADC 8 during a specific period (θ2 in FIG. 6) described later, and extracts a feature point (such as a maximum value) of the light reception signal from the light reception module 7 at a predetermined time. Based on the feature points, the presence or absence of a failure in the optical system such as the LD 2a, the rotary scanning unit 4, or the APD 7a is diagnosed.

  Specifically, for example, failure diagnosis unit 1b compares the light reception signal output from light reception module 7 via ADC 8 with a predetermined threshold value. If the light reception signal is equal to or greater than the threshold value, the laser light is normally projected and received, so that it is diagnosed that there is no failure in the optical system. If the light reception signal is less than the threshold value, the laser beam is not normally projected and received, so that it is diagnosed that the optical system has a failure.

  Note that the threshold value that the object detection unit 1a compares with the light reception signal and the threshold value that the failure diagnosis unit 1b compares with the light reception signal may be the same or different.

  The multiplication control unit 1c controls the level of the light reception signal output from the light reception module 7 by controlling the signal multiplication unit 9 and changing the multiplication factor of the APD 7a. This specific method will be described with reference to FIGS.

  FIG. 4 is a diagram showing the relationship between the reverse voltage of the APD 7a and the multiplication factor. FIG. 5 is a diagram showing the relationship between the multiplication factor and output of the APD 7a.

  As shown in FIG. 4, as the reverse voltage applied to the APD 7a increases, the multiplication factor of the APD 7a increases. As shown in FIG. 5, as the multiplication factor of the APD 7a increases, the output signal (the output current from the APD 7a or the output voltage from the TIA 7b) corresponding to the light receiving state of the APD 7a increases.

  As shown in FIG. 5, the shot noise caused by the individual characteristics of the APD 7a, disturbance light, etc. increases as the multiplication factor of the APD 7a becomes larger than a certain level. The dark current of the APD 7a also increases when the multiplication factor of the APD 7a becomes larger than a certain level (not shown). Changes in shot noise and dark current with respect to the multiplication factor of the APD 7a depend on temperature.

  The multiplication control unit 1c in FIG. 3 controls the reference voltage generation unit 9b of the signal multiplication unit 9, and changes the reference voltage input from the reference voltage generation unit 9b to the reverse voltage generation unit 9a by PWM. Then, the reverse voltage applied from the reverse voltage generator 9a to the APD 7a is changed, and the multiplication factor of the APD 7a is changed. As a result, the output level of the APD 7a changes, and the multiplication factor of the received light signal output from the light receiving module 7 also changes. That is, the signal multiplying unit 9 sets the multiplication factor of the received light signal and causes the light receiving module 7 to output a received light signal at a level corresponding to the multiplication factor.

  For example, as the reference voltage input from the reference voltage generation unit 9b to the reverse voltage generation unit 9a is increased, the reverse voltage applied from the reverse voltage generation unit 9a to the APD 7a is increased, and the multiplication factor of the APD 7a is also increased. As the multiplication factor of the APD 7a increases, the output of the APD 7a increases, and the level of the light reception signal output from the light reception module 7 increases.

  FIG. 6 is a diagram illustrating the operation timing of the object detection apparatus 100. Specifically, FIG. 6 shows the operation of each unit while the mirror 4a of the rotary scanning unit 4 makes one rotation from the origin.

  The origin (star) of the mirror 4a of the rotary scanning unit 4 is such that, for example, both plate surfaces of the mirror 4a are relative to the optical axis (one-dot chain line) of the light from the LD 2a, as shown by the dotted lines in FIGS. 1A and 1B. It is a position that takes a vertical posture. The mirror 4a of the rotary scanning unit 4 continues to rotate in one direction (counterclockwise in FIGS. 1A and 1B) at a predetermined rotational speed (constant speed).

By driving the motor 4c of the rotary scanning unit 4, while the mirror 4a is rotated from the origin by a predetermined rotation angle theta _1, a laser beam is projected from LD2a, the object detecting the laser light by the mirror surface 4a This is a scanning period in which a predetermined range in front of the apparatus 100 is scanned. In the scanning period θ ₁ , when the laser light projected to a predetermined range is reflected by the object 50, the reflected light is reflected by the surface of the mirror 4 a and passes through the light receiving lens 16 and the reflecting mirror 17 to the APD 7 a. Received light. Then, based on the light reception signal input from the light receiving module 7 via the ADC 8 according to the light receiving state of the APD 7a, the object detection unit 1a detects the presence / absence of the object 50 and the distance to the object 50. That is, the scanning period theta ₁ by the mirror surface 4a is the object detection period.

The scanning period θ ₁ by the surface of the mirror 4a is different from the scanning angle range Z shown in FIGS. 1A and 1B. Further, as will be described later, the scanning period θ ₅ by the back surface of the mirror 4a is also different from the scanning angle range Z. The scanning angle range Z is the sum of the angle range on the object 50 side where the mirror 4a scans the laser beam with the surface and the angle range on the object 50 side where the mirror 4a scans the laser beam with the back surface as described later. is there.

After passing the scanning period theta _1, while the mirror 4a is rotated by a predetermined rotation angle theta ₂ is a rest period. In idle period theta _2, the light emitting operation of LD2a, each part of the light reception operation of the receiver module 7 including the APD7a, signal conversion operation of ADC 8, the detection operation of the object detecting unit 1a, and diagnostic operations for fault diagnosis portion 1b is paused The The same applies to pause periods θ ₄ and θ ₆ described later.

After the rest period θ _2, while the mirror 4 a rotates by a predetermined rotation angle θ ₃ , laser light is projected from the LD 2 a, and the laser light is reflected by the back surface of the mirror 4 a and the light guide 15 is provided. It is a specific period that proceeds in a specific direction. In certain period theta _3, the laser beam traveling in a specific direction, is incident from the guide surface 15a into the light guide 15, passes through the inside of the light guide 15 and emitted from the outlet surface 15b. Then, the emitted light is reflected by the back surface of the mirror 4 a and is received by the APD 7 a via the light receiving lens 16 and the reflecting mirror 17. At these times, the failure diagnosis unit 1b diagnoses the presence or absence of a failure in the optical system based on the light reception signal input from the light reception module 7 via the ADC 8 according to the light reception state of the APD 7a. That is, the specific period θ ₃ is a failure diagnosis period of the optical system.

After the specific period θ ₃ has passed, the rest period is also during which the mirror 4a rotates by a predetermined rotation angle θ ₄ . Then, after the rest period θ ₄ , the laser beam is projected from the LD 2 a while the mirror 4 a rotates by a predetermined rotation angle θ ₅ , and the laser beam is scanned within a predetermined range by the back surface of the mirror 4 a. It is a period. In the scanning period θ ₅ , when the laser light projected to a predetermined range is reflected by the object 50, the reflected light is reflected by the back surface of the mirror 4 a and passes through the light receiving lens 16 and the reflecting mirror 17 to the APD 7 a. Received light. Then, based on the light reception signal input from the light receiving module 7 via the ADC 8 according to the light receiving state of the APD 7a, the object detection unit 1a detects the presence / absence of the object 50 and the distance to the object 50. That is, the scanning period θ ₅ by the back surface of the mirror 4a is also an object detection period, like the scanning period θ ₁ .

After passing the scanning period theta _5, also a rest period during which the mirror 4a is rotated by a predetermined rotation angle theta _6. Then, after the rest period θ ₆ , the mirror 4a returns to the origin and enters a state of one rotation. Thereafter, the subsequent periods θ _{1 to} θ ₆ are repeated again.

  FIG. 7 is a diagram showing an output signal when the light receiving module 7 detects an object. FIG. 8 is a diagram showing an output signal at the time of failure diagnosis of the light receiving module 7. FIG. 9 is a diagram showing an output signal at the time of failure diagnosis of the conventional light receiving module 7. 7 to 9, the horizontal axis indicates time, and the vertical axis indicates voltage.

  As shown in FIGS. 7 to 9, low level noise (such as shot noise of the APD 7a) is always superimposed on the output signal (light reception signal) of the light reception module 7.

In the scanning periods (object detection periods) θ ₁ and θ ₅ shown in FIG. 6, the laser light projected from the LD 2a is scanned within a predetermined range by the mirror 4a of the rotary scanning unit 4 as described above. In the scanning periods θ ₁ and θ ₅ , the reference voltage generation unit 9b of the multiplication control unit 1c inputs the reference voltage for object detection to the reverse voltage generation unit 9a, and the reverse voltage generation unit 9a By applying the reverse voltage V1 to the APD 7a based on the reference voltage, the multiplication factor of the APD 7a is set to α times. As a result, the light receiving signal multiplied by α is output from the light receiving module 7.

In the scanning periods θ ₁ and θ ₅ , when the laser light from the LD 2 a is reflected by the object 50 within a predetermined range, the reflected light is received by the APD 7 a and the received light signal output from the light receiving module 7 is 1 in FIG. A reflected light signal is generated as surrounded by a dotted line. Since the level of the reflected light signal is remarkably higher than the noise level, it is easy for the object detection unit 1a to detect the reflected light signal separately from the noise. The object detection unit 1a detects the presence / absence of the object 50 and the distance to the object 50 based on the reflected light signal of FIG.

In particular the period (fault diagnosis period) theta ₃ shown in FIG. 6, as described above, the laser light projected from LD2a is reflected by the mirror 4a of the rotational scanning unit 4, it travels in a specific direction. The laser light enters the light guide 15 from the introduction surface 15a in a specific direction, passes through the inside of the light guide 15, exits from the lead-out surface 15b, is reflected by the mirror 4a, and is received by the APD 7a. Is done.

Conventionally, the reverse voltage applied to the APD 7a is approximately the same in the failure diagnosis period θ ₃ and the object detection periods θ ₁ and θ ₅ . That is, similarly to the object detection periods θ ₁ and θ ₅ , the reverse voltage V1 is applied to the APD 7a in the failure diagnosis period θ _{3 and} the multiplication factor of the APD 7a is α times. Therefore, if the optical system is not broken, the laser light from the LD 2a is received by the APD 7a via the mirror 4a, the light guide 15 and the like, and the received light signal output from the light receiving module 7 is shown in FIG. A diagnostic light signal was generated as surrounded by a one-dot chain line.

  The level of the diagnostic light signal in FIG. 9 is slightly higher than the level of the reflected light signal in FIG. This is because, in the light guide 15 located only in the light projecting / receiving path (FIGS. 1B and 2B) for failure diagnosis, the light transmittance is lowered as described above in order to suppress the stray light generated when detecting the object. This is because the amount of light passing through the light projecting / receiving path for failure diagnosis is set smaller than the amount of light passing through the light projecting / receiving path for detecting the object (FIGS. 1A and 2A). The failure diagnosis unit 1b diagnoses the presence or absence of a failure of the optical system based on the diagnostic light signal. However, there is a case where a diagnostic light signal having a low level as shown in FIG. The accuracy of fault diagnosis was reduced.

  Specifically, for example, although there is no failure in the optical system, the failure diagnosis unit 1b cannot detect the diagnostic optical signal in FIG. 9, and thus erroneously diagnoses that there is a failure in the optical system. There was a fear.

On the other hand, in the present embodiment, in the failure diagnosis period θ ₃ , the reference voltage generation unit 9b of the multiplication control unit 1c inputs the reference voltage for failure diagnosis to the reverse voltage generation unit 9a, and the reverse voltage generation unit 9a However, by applying the reverse voltage V2 to the APD 7a based on this reference voltage, the multiplication factor of the APD 7a is set to β times. As a result, a light reception signal multiplied by β times is output from the light reception module 7. Reference voltage for fault diagnosis is higher than the reference voltage for object detection, since the reverse voltage V2 higher than the reverse voltage V1, the multiplication factor β of APD7a fault diagnosis period theta ₃ object detection period theta _1, theta ₅ of It is higher than the multiplication factor α of APD7a. Therefore, if the optical system is not broken, the laser light from the LD 2a is received by the APD 7a via the mirror 4a, the light guide 15 and the like, so that the light receiving signal output from the light receiving module 7 is shown in FIG. A diagnostic optical signal is generated as enclosed by a one-dot chain line.

  The level of the diagnostic optical signal in FIG. 8 is sufficiently higher than the level of noise and smaller than the level of the reflected optical signal in FIG. 7, but is higher than the level of the conventional diagnostic optical signal in FIG. That is, by increasing the multiplication factor of the APD 7a from α times to β times, the multiplication factor of the output signal (light reception signal) of the light receiving module 7 corresponding to the light receiving state of the APD 7a is increased. Since the failure diagnostic unit 1b can reliably detect a diagnostic light signal having a large level as shown in FIG. 8 from noise, it can accurately diagnose the presence or absence of a failure in the optical system based on the diagnostic light signal.

According to the above embodiment, in the scanning periods (object detection periods) θ ₁ and θ ₅ in which the laser light projected from the LD 2 a of the light emitting module 2 is scanned to a predetermined range by the mirror 4 a of the rotary scanning unit 4, the laser light is used. APD7a but not guided to APD7a light receiving module 7 by the light guide 15, during a certain period of time (fault diagnosis period) theta ₃ which laser light travels a specific direction out of a predetermined range, the laser light is received module 7 by the light guide 15 Led to. Then, based on the light receiving signal output from the light receiving module 7 in accordance with the light receiving state of the APD 7a at that time, the failure diagnosis unit 1b diagnoses the presence or absence of the failure of the optical system. For this reason, the amount of light passing through the light projecting / receiving path for failure diagnosis is made smaller than the amount of light passing through the light projecting / receiving path for detecting the object, so that stray light at the time of detecting the object in the light guide 15 is reduced. It is possible to improve the accuracy of detection of the presence / absence of the object 50 and the distance to the object 50 by the detection unit 1a.

In the above embodiment, the multiplication factor β of the received light signal output from the light receiving module 7 in the specific period (failure diagnosis period) θ ₃ is set to the light receiving module 7 in the scanning periods (object detection periods) θ ₁ and θ ₅ . Is larger than the multiplication factor α of the received light signal output from the. Therefore, it is possible to improve the diagnostic accuracy of the presence or absence of increasing the level of the received light signal in a particular time period theta _3, the optical system by the failure diagnosis section 1b failure. Furthermore, in the scanning periods θ ₁ and θ ₅ , the gain of the received light signal is not increased to the same level as that of the specific period θ ₃ , so that the level of noise included in the received light signal increases during the scanning periods θ ₁ and θ ₅ . Can be prevented. For this reason, it becomes possible to distinguish noise and a reflected light signal correctly, and to suppress that the detection accuracy of the presence or absence of the target object 50 or the distance to the target object 50 falls.

  In the above embodiment, the light transmittance of the light guide 15 is set lower than the light transmittance of the transmission window 20. For this reason, the amount of light passing through the light projecting / receiving path for failure diagnosis is surely reduced from the amount of light passing through the light projecting / receiving path for detecting an object, so that stray light generated in the light guide 15 at the time of detecting the object is further reduced. The accuracy of detecting the presence or absence of the object 50 and the distance to the object 50 by the object detection unit 1a can be further improved.

In the above embodiment, the multiplication factor of the light receiving signal output from the light receiving module 7 is changed by changing the reverse voltage applied to the APD 7a and changing the multiplication factor of the APD 7a. Therefore, the scanning period theta _1, from the inverse voltage applied to the APD7a the theta _5, by a simple control that increases the reverse voltage applied to APD7a the particular period theta _3, a multiplication factor of a specific period theta ₃ scanning periods theta _1, it is possible to be larger than the multiplication factor of the theta _5.

In the above embodiment, each scanning period θ ₁ , θ ₅ is longer than the specific period θ ₃ . Further, during the scanning periods θ ₁ and θ ₅ , the rotary scanning unit 4 reflects the laser light from the LD 2a by the mirror 4a and scans it within a predetermined range, and reflects the reflected light from the object 50 within the predetermined range by the mirror 4a. To the APD 7a. Further, rotational scanning unit 4, in a specific period theta _3, guided to the light guide 15 reflects the laser beam from LD2a a mirror 4a, led to APD7a it reflects the light emitted from the light guide 15 in the mirror 4a Yes. For this reason, the light projecting / receiving amount in the light projecting / receiving path for detecting the object is surely made larger than the light projecting / receiving light amount in the light projecting / receiving path for failure diagnosis, and the presence / absence of the object 50 and the object 50 by the object detecting unit 1a. The distance detection accuracy can be further improved.

In the above embodiments, the specified time period theta _3, since the rotational scanning unit 4 is not guided to APD7a disturbance light by the mirror 4a, possible to reduce the level of noise included in the light receiving signal output from the light receiving module 7 Can do. Therefore, the specific time period theta _3, by increasing the multiplication factor of the APD7a, even by increasing the level of the light receiving signal output from the light receiving module 7, is hardly affected by noise, the fault diagnosis unit 1b to the light receiving signal Based on this, it is possible to diagnose the presence or absence of failure of the optical system with higher accuracy.

Furthermore, in the above embodiment, the light guide 15 does not always guide disturbance light to the APD 7a, so that the level of noise included in the light reception signal output from the light reception module 7 can be further reduced. For this reason, it becomes difficult to be influenced by noise in the scanning periods θ ₁ and θ ₅ , and the object detection unit 1a can detect the presence / absence of the object 50 and the distance to the object 50 with higher accuracy. Moreover, hardly affected by noise during a certain period of time theta _3, failure diagnosis unit 1b can more accurately diagnosing the presence or absence of a failure of the optical system.

  The present invention can employ various embodiments other than those described above. For example, in the above embodiment, an example in which the LD 2a is used as the light emitting element and the APD 7a is used as the light receiving element has been described, but the present invention is not limited to these. An appropriate number of light emitting elements other than the LD 2 a may be provided in the light emitting module 2. Further, an appropriate number of light receiving elements other than the APD 7a may be provided in the light receiving module 7.

  For example, as shown in FIG. 10, a SPAD (Single Photon Avalanche Diode) 7 s may be provided in the light receiving module 7 as a light receiving element. SPAD7s is a Geiger mode APD. The SPAD 7s is paired with the TIA 7b and the constant current circuit 7d. A plurality of SPADs 7s, TIAs 7b, and constant current circuits 7d are provided in the light receiving module 7 (detailed illustration is omitted).

  Further, one pixel (basic unit) is formed by connecting one end of a quenching resistor to a SPAD assode, and an MPPC (Multi-Pixel Photon Counter) configured by connecting a large number of the pixels in parallel is used as a light receiving module. One or more may be provided (not shown).

  In addition, as shown in FIG. 11, a PIN type PD (Photo Diode) 7g may be provided in the light receiving module 7 as a light receiving element. The anode of the PD 7g is connected to the TIA 7b, and the cathode of the PD 7g is connected to the power source + V. The PD 7g and the TIA 7b form a pair, and a plurality of PDs 7g and TIAs 7b are provided in the light receiving module 7 (detailed illustration is omitted).

In the above embodiment, the example in which the multiplication factor of the light receiving signal output from the light receiving module 7 is changed by changing the multiplication factor of the APD 7a that is the light receiving element has been described. However, the present invention is limited to this. It is not a thing. In addition to this, as shown in FIG. 11, for example, a VGA (Variable Gain Amplifier) 7f is connected to the output side of the MUX 7c, and the gain when the output signal of the MUX 7c is amplified by the VGA 7f is changed to output from the light receiving module 7. The multiplication factor of the received light signal may be changed. The VGA 7f is an example of the “signal multiplication unit” in the present invention. Multiplication control unit 1d of the control unit 1 adjusts the gain of VGA7f, scanning period theta _1, from multiplication factor of the light receiving signal output from the light receiving module 7 to theta _5, the light receiving module 7 to a specific period theta ₃ Increase the multiplication factor of the received light signal. In FIG. 11, the PD 7g is used as the light receiving element, but other light receiving elements may be used.

In the above embodiment, at the time of failure diagnosis (specific period θ ₃ ), the laser light from the LD 2a is reflected by the mirror 4a of the rotary scanning unit 4 and guided to the light guide 15, and the light emitted from the light guide 15 is reflected. Although an example in which the light is reflected by the mirror 4a and led to the APD 7a is shown, the present invention is not limited to this. In addition to this, for example, by changing the structure of the light guide or the rotational scanning unit, or changing the arrangement of the light guide, the rotational scanning unit, or the APD, the laser from the LD can be used without going through the rotational scanning unit. Light may be incident on the light guide, or light emitted from the light guide may be received by the APD. Further, instead of the light guide 15, for example, a light guide part such as a hole or notch formed in the wall may be provided.

Moreover, although the example using the rotation scanning part 4 which has the plate-shaped mirror 4a in which both surfaces became a reflective surface was shown in the above embodiment, this invention is not limited only to this. In addition, a rotary scanning unit having a mirror having three or more side surfaces as reflection surfaces, such as a polygon mirror, may be used. Further, at the time of detecting an object (scanning periods θ ₁ , θ ₅ ), for example, a laser beam from the LD is scanned in a predetermined range by a rotary scanning unit, and reflected light from an object in the predetermined range is scanned by the rotary scanning unit. The shape of the rotational scanning unit may be designed so that light is received by the light receiving element without going through, or the rotational scanning unit and the light receiving element may be arranged.

  Moreover, although the voltage signal was output from the light reception module 7 and the example processed in the back | latter stage was shown in the above embodiment, this invention is not limited only to this. In addition to this, for example, a current signal corresponding to the output current from each light receiving element is output from the light receiving module and processed by a subsequent ADC or control unit to detect the presence or absence of the object and the distance to the object. Alternatively, the presence or absence of an optical system failure may be diagnosed.

  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 1a Object detection part 1b Failure diagnosis part 1c, 1d Multiplication control part 2 Light emitting module (light emission part)
2a LD (light emitting device)
4 Rotating scanning unit 4a Mirror 7 Light receiving module (light receiving unit)
7a APD (light receiving element)
7f VGA (signal multiplier)
7g PD (light receiving element)
7s SPAD (light receiving element)
9 Signal multiplier 9a Reverse voltage generator 15 Light guide (light guide)
20 Transmission window 50 Object 100 Object detection device Z Scanning angle range (predetermined range)
θ ₁ , θ ₅ scanning period θ ₃ specific period α scanning period APD multiplication factor β specific period APD multiplication factor

Claims (5)

A light emitting unit having a light emitting element;
A rotation scanning unit that has a mirror and rotates the mirror to reflect the projection light from the light-emitting unit by the mirror and scan a predetermined range;
A light receiving unit having a light receiving element that receives the projection light or reflected light from the object within the predetermined range of the projection light;
Object detection for detecting the object based on a light receiving signal output from the light receiving unit according to a light receiving state of the light receiving element during a scanning period in which the projection light is scanned to the predetermined range by the rotary scanning unit. And
A light guide unit that guides the projection light to the light receiving unit in a specific period in which the projection light travels in a specific direction outside the predetermined range;
In the object detection device comprising a failure diagnosis unit that diagnoses the presence or absence of a failure based on the light reception signal output from the light reception unit during the specific period,
A signal multiplication unit that sets a multiplication factor of the light reception signal, and outputs a light reception signal of a level corresponding to the multiplication factor from the light reception unit;
A multiplication control unit for controlling the multiplication factor of the light reception signal,
The multiplication control unit, wherein the multiplication factor of the light reception signal in the specific period is larger than the multiplication factor of the light reception signal in the scanning period. The object detection apparatus according to claim 1,
A transmission window provided between the rotation scanning unit and the predetermined range, and further configured to transmit the projection light and the reflected light of the projection light from the object;
The object detection device according to claim 1, wherein a light transmittance of the light guide unit is lower than a light transmittance of the transmission window. In the object detection apparatus according to claim 1 or 2,
The light receiving element comprises an APD (Avalanche Photo Diode),
The signal multiplication unit includes a reverse voltage generation unit that generates a reverse voltage and applies the reverse voltage to the APD.
The multiplication control unit is configured to change a multiplication factor of the light reception signal by changing a reverse voltage applied to the APD by the reverse voltage generation unit. The object detection apparatus according to any one of claims 1 to 3,
The scanning period is longer than the specific period,
The rotational scanning unit
In the scanning period, the reflected light is reflected by the mirror and guided to the light receiving unit,
The object detection apparatus according to claim 1, wherein disturbance light from outside the object detection apparatus is not guided to the light receiving unit by the mirror during the specific period. The object detection device according to any one of claims 1 to 4,
The light guide unit does not guide disturbance light from the outside of the target object detection device to the light receiving unit.

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