JP2018004374A - Optical scanner and distance measurement device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical scanner and a distance measurement device which can perform highly accurate control of optical scanning, and whose structure is downsized and manufacturing cost can be reduced.SOLUTION: An optical scanner 10 comprises: a light source unit 12 for outputting first output light and second output light; a light deflection unit 15 which is provided with a deflector for deflecting the first output light and second output light, and displaces the light advanced from the deflector; a PD 14 that is a first light detection unit for detecting first detection light being the first output light having been advanced from the deflector to a detection area and having been reflected by an object present in the detection area; a PD 13 that is a second light detection unit for detecting second detection light being the second output light having been advanced from the deflector in a direction other than the detection area; a first light source drive unit for driving the light source unit 12 by applying a first power supply voltage and causing the first output light to be output from the light source unit 12; and a second light source drive unit for driving the light source unit 12 by applying a second power supply voltage different from the first power supply voltage and causing the second output light to be output from the light source unit 12.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an optical scanning device and a distance measuring device.

  Conventionally, a distance measuring device that measures the distance to an object by projecting light and detecting the light reflected by the object is known. The distance measuring device obtains the distance to the object by converting the elapsed time from when the current is applied to the light source to when the reflected light from the object is detected.

  Some distance measuring devices attached to vehicles and the like are equipped with an optical scanning device that scans light by driving a deflector that deflects light from a light source. The distance measuring device can detect an object from a wider detection region by using an optical scanning device.

  For example, Patent Document 1 discloses a technique of a laser array driving circuit that scans light by sequentially turning on a plurality of laser diodes.

  The optical scanning device can control the optical scanning with high accuracy by synchronizing the driving of the light source with the driving of the deflector. In addition, the optical scanning device is desired to be able to reduce cost and size due to the use of components with high withstand voltage in the circuit for driving the light source.

  The present invention has been made in view of the above, and an object of the present invention is to provide an optical scanning device and a distance measuring device capable of highly accurate control of optical scanning, downsizing of the configuration, and reduction of manufacturing cost. And

  In order to solve the above-described problems and achieve the object, the present invention is an optical scanning device that scans light in a detection region, and a light source unit that outputs first output light and second output light. A deflector that deflects the first output light and the second output light from the light source unit, a light deflector that displaces the light traveling from the deflector, and the detection region from the deflector And a first light detection unit that detects the first detection light that is the first output light reflected by the object in the detection region, and the deflector in a direction other than the detection region. A second light detection unit that detects the second detection light that is the second output light that has traveled, and the light source unit is driven by applying a first power supply voltage, and the first output from the light source unit A first light source driving unit for outputting light, and a second power source voltage different from the first power source voltage. By the application drives the light source unit, characterized in that it comprises a second light source driving section for outputting the second output light from the light source unit.

  According to the present invention, it is possible to perform highly accurate control of optical scanning, and it is possible to reduce the size of the configuration and reduce the manufacturing cost.

FIG. 1 is a diagram illustrating a vehicle on which a system including a distance measuring device according to the first embodiment is mounted. FIG. 2 is a block diagram of a vehicle control system including the distance measuring device shown in FIG. FIG. 3 is a diagram illustrating a partial configuration including a light-emitting optical system in the optical scanning device illustrated in FIG. 2 and light beams traveling from the light source unit to the detection region. FIG. 4 is a diagram illustrating a partial configuration including a light receiving optical system in the optical scanning device and a light beam traveling from the detection region to the PD. FIG. 5 is a diagram illustrating a light beam traveling from the light source unit to the mirror and a light beam traveling from the mirror to the PD. FIG. 6 is a diagram illustrating a partial configuration including a light-emitting optical system in the optical scanning device and a light beam traveling from the light source unit to the PD through the deflector. FIG. 7 is a diagram illustrating a configuration example of the light receiving circuit illustrated in FIG. 2. FIG. 8 is a diagram illustrating driving of the light source unit according to the first drive signal. FIG. 9 is a diagram illustrating driving of the light source unit according to the first drive signal. FIG. 10 is a diagram illustrating driving of the light source unit according to the second drive signal. FIG. 11 is a diagram illustrating a lighting pattern of the light source unit according to the first drive signal and the second drive signal. FIG. 12 is a diagram illustrating a circuit configuration included in the optical scanning device according to the first embodiment. FIG. 13 is a diagram illustrating a circuit configuration according to a comparative example of the first embodiment. FIG. 14 is a diagram illustrating a circuit configuration included in the optical scanning device according to the second embodiment. FIG. 15 is a diagram illustrating a circuit configuration included in the optical scanning device according to the third embodiment. FIG. 16 is a diagram illustrating a circuit configuration included in the optical scanning device according to the fourth embodiment. FIG. 17 is a diagram illustrating a circuit configuration included in the optical scanning device according to the fifth embodiment. FIG. 18 is a diagram illustrating a circuit configuration included in the optical scanning device according to the sixth embodiment. FIG. 19 is a diagram illustrating a circuit configuration included in the optical scanning device according to the seventh embodiment.

  Exemplary embodiments of an optical scanning device and a distance measuring device will be described below in detail with reference to the accompanying drawings.

(First embodiment)
FIG. 1 is a diagram illustrating a vehicle 101 on which a system including a distance measuring device 100 according to the first embodiment is mounted. A vehicle control system that is an example of a system including the distance measuring device 100 is mounted on the vehicle 101. The vehicle control system controls the vehicle 101 according to the measurement result of the distance measuring device 100.

  The distance measuring device 100 is, for example, a laser radar (Light Detection and Ranging, LIDAR). The distance measuring device 100 is attached in front of the vehicle 101. The distance measuring device 100 detects an object such as a preceding vehicle, an oncoming vehicle, a pedestrian, or an obstacle existing in the forward visual field from the vehicle 101, and measures the distance to the detected object.

  FIG. 2 is a block diagram of a vehicle control system including the distance measuring device 100. The vehicle control system includes a distance measuring device 100 and an ECU (Electronic Control Unit) 20. The distance measuring device 100 includes an optical scanning device 10 and a time measuring circuit 11.

  The optical scanning device 10 scans light in a detection region in the front visual field from the vehicle 101. The optical scanning device 10 includes a light source unit 12, photodiodes (PDs) 13 and 14 that are light receiving elements, a light deflecting unit 15, a light source driving circuit 16, light receiving circuits 17 and 18, a deflector driving circuit 19, and a scanning optical system. 21, a light emitting optical system 22 and a light receiving optical system 23 are provided.

  The light source unit 12 includes a laser diode (LD) that is a light emitting element, and outputs first output light and second output light. The light source drive circuit 16 drives the light source unit 12 according to the light source drive signal from the ECU 20. The light emitted from the light source unit 12 enters the light deflecting unit 15 through the light emitting optical system 22.

  The light deflecting unit 15 includes a deflector that deflects light from the light source unit 12 and a drive mechanism that rotates the deflector. The light deflecting unit 15 displaces the light traveling from the deflector by rotating the deflector. The deflector drive circuit 19 drives the deflector according to a deflector drive signal from the ECU 20.

  The light deflecting unit 15 advances the first output light from the light source unit 12 to the detection region in accordance with driving of the deflector. The first output light from the light deflecting unit 15 is emitted from the optical scanning device 10 through the scanning optical system 21. The optical scanning device 10 scans the first output light from the light source unit 12 by driving the deflector.

  The first output light traveling from the optical scanning device 10 toward the object in the detection area is scattered by reflection from the object. The scanning optical system 21 guides light incident on the scanning optical system 21 out of scattered light from the object to the light deflecting unit 15. The light deflecting unit 15 deflects the light incident from the scanning optical system 21. The light receiving optical system 23 guides the light from the light deflection unit 15 to the PD 14 as the first light detection unit. PD14 detects the 1st detection light which is the light which injected from the optical deflection | deviation part 15, and produces | generates the signal according to the incident light quantity. The light receiving circuit 18 generates a light receiving signal corresponding to the signal from the PD 14.

  In addition, the light deflecting unit 15 causes the second output light from the light source unit 12 to travel to the PD 13 as the second light detecting unit in accordance with the driving of the deflector. The second output light from the light deflecting unit 15 enters the PD 13 via the light emitting optical system 22. PD13 detects the 2nd detection light which is the light which progressed toward the PD13 from the light deflection part 15, and produces | generates the signal according to the incident light quantity. The light receiving circuit 17 generates a synchronization detection signal corresponding to the operation of the deflector based on the signal from the PD 13.

  The time measuring circuit 11 as a distance calculating unit calculates the time difference between the light source driving signal from the ECU 20 and the light receiving signal from the light receiving circuit 18, so that light travels from the light source unit 12 to the PD 13 through the object. Measure the time required. The time measuring circuit 11 converts the measured time into a distance, and calculates the distance between the distance measuring device 100 and the object. The distance measuring device 100 outputs a measured value of the distance obtained by the time measuring circuit 11.

  The ECU 20 performs traveling control of the vehicle 101 according to the positional relationship with the object detected in the detection area, using the measurement value input from the distance measuring device 100. In addition, the ECU 20 outputs a light source drive signal to the light source drive circuit 16 and the time measurement circuit 11 and outputs a deflector drive signal to the deflector drive circuit 19. By supplying the light source drive signal, the timing of which is adjusted using the synchronization detection signal from the light receiving circuit 17, to the light source drive circuit 16, the driving of the light source unit 12 is linked to the operation of the deflector.

  FIG. 3 is a diagram illustrating a partial configuration including the light-emitting optical system 22 in the optical scanning device 10 and light beams traveling from the light source unit 12 toward the detection region AR. The light emitting optical system 22 includes a coupling lens 32, a mirror 33, and a condenser lens 34.

  The X axis, the Y axis, and the Z axis are three axes that are perpendicular to each other. A plus X direction indicated by an arrow on the X axis in FIG. 3 is a straight forward direction of the vehicle 101. The Z axis is perpendicular to the road surface on which the vehicle 101 is traveling, and the plus Z direction is a direction away from the road surface. In FIG. 3, the direction from the back to the front of the paper is the plus Z direction. The light from the optical scanning device 10 scans from the plus Y side, which is the side indicated by the Y-axis arrow in FIG. 3, toward the opposite minus Y side. FIG. 3 shows an arrangement example of the light source unit 12, the PD 13, the light emitting optical system 22, and the deflector 30 in the X-axis direction and the Y-axis direction.

  The coupling lens 32 converts the light emitted from the light source unit 12 into parallel light or divergent light that diverges slightly. The coupling lens 32 is a plano-convex lens, for example. The light emitting optical system 22 may be provided with a coupling optical system including a plurality of lenses or mirrors instead of the coupling lens 32.

  The mirror 33 includes a reflecting surface 35 formed on one surface of a flat plate as a base material. The mirror 33 reflects the light from the coupling lens 32 toward the deflector 30. Space saving is achieved in the optical scanning device 10 by folding the optical path between the light source unit 12 and the deflector 30 by the mirror 33.

  The deflector 30 includes two reflecting surfaces 31. The reflecting surface 31 is formed on one surface of a flat plate that is a base material of the deflector 30 and a surface on the back side thereof. The deflector 30 rotates in a fixed direction around a rotation axis O parallel to the Z axis. By changing the incident angle of the light beam from the mirror 33 on the reflecting surface 31 by the rotation of the deflector 30, the light deflecting unit 15 displaces the light beam traveling from the deflector 30 toward the detection area AR in the minus Y direction. Let

  The optical scanning device 10 scans light in the detection area AR when the deflection angle of the deflector 30 changes within a predetermined first angle range. The deflection angle is an angle formed by the perpendicular of the reflecting surface 31 and the X axis. The deflection angle when the perpendicular of the reflecting surface 31 is tilted to the plus Y side with respect to the X axis is a plus deflection angle, and the deflection angle when tilted to the minus Y side is a minus deflection angle. To do.

  For example, when the deflection angle is + θ1, the light from the optical scanning device 10 travels toward the plus Y side end of the detection area AR, and when the deflection angle is −θ1, the light from the optical scanning device 10 Advances toward the end of the detection area AR on the minus Y side. In this case, the first angle range is a range from + θ1 to −θ1. However, θ1 is a predetermined angle smaller than 90 degrees.

  FIG. 4 is a diagram illustrating a partial configuration including the light receiving optical system 23 in the optical scanning device 10 and a light beam traveling from the detection region AR to the PD 14. The light receiving optical system 23 includes a mirror 33 and an imaging optical system 36. The mirror 33 is shared by the light emitting optical system 22 and the light receiving optical system 23. FIG. 4 shows an arrangement example of the PD 14, the light receiving optical system 23, and the deflector 30 in the X axis direction and the Y axis direction.

  The imaging optical system 36 includes, for example, a plano-convex lens and a meniscus lens. The imaging optical system 36 may be composed of one lens, or may be an optical system including three or more lenses or mirrors.

  As shown in FIG. 3, the light that has entered the object out of the light that has traveled to the detection area AR is scattered by reflection from the object. Of the scattered light from the object, light that has traveled in the opposite direction to that incident on the object enters the deflector 30. The deflector 30 is shared when the light from the light source unit 12 travels to the detection area AR and when the light from the object in the detection area AR travels to the PD 14. The imaging optical system 36 converges the light incident on the imaging optical system 36 after being reflected by the deflector 30 and the mirror 33 onto the PD 14.

  FIG. 5 is a diagram illustrating a light beam traveling from the light source unit 12 to the mirror 33 and a light beam traveling from the mirror 33 to the PD 14. FIG. 5 shows an arrangement example of the light source unit 12, the light emitting optical system 22, the PD 14, and the light receiving optical system 23 in the X-axis direction and the Z-axis direction. The light emitting optical system 22 and the light receiving optical system 23 are arranged with their positions in the Z-axis direction being different from each other. The reflection surface 35 of the mirror 33 reflects the light from the light source unit 12 toward the deflector 30 and reflects the light from the deflector 30 toward the PD 14.

  FIG. 6 is a diagram illustrating a partial configuration including the light emitting optical system 22 in the optical scanning device 10 and a light beam traveling from the light source unit 12 to the PD 13 via the deflector 30. 6 shows the light source unit 12, the PD 13, the light emitting optical system 22, and the deflector 30 in the X-axis direction and the Y-axis direction, as in FIG.

  When the deflection angle of the deflector 30 is outside the first angle range, light scanning in the detection area AR is not performed. In the optical scanning device 10, when the deflection angle of the deflector 30 is within a second angle range that is a predetermined angle range, the light incident on the deflector 30 from the mirror 33 travels in a direction other than the detection area AR, It enters the mirror 33 again. Furthermore, the light reflected by the mirror 33 travels toward the PD 13. The second angle range is an angle range other than the first angle range. For example, when the deflection angle of the deflector 30 is a predetermined angle + θ2 included in the second angle range, the light from the optical scanning device 10 enters the approximate center of the light receiving surface of the PD 13. θ2 is an angle larger than θ1.

  The deflector 30 is not limited to the one provided with the two reflecting surfaces 31 formed in a flat plate. The deflector 30 may include one or three or more reflecting surfaces 31, and the shape of the base material on which the reflecting surfaces 31 are formed is arbitrary.

  FIG. 7 is a diagram illustrating a configuration example of the light receiving circuit 18. The light receiving circuit 18 includes an amplifier 37 and a comparator 38. The amplifier 37 amplifies the signal from the PD 14. The comparator 38 compares the output voltage of the amplifier 37 with a threshold Th. The comparator 38 inverts the bit value as a comparison result when the magnitude relationship between the output voltage of the amplifier 37 and the threshold Th is inverted.

  The light receiving circuit 18 outputs a signal indicating the comparison result of the comparator 38 as a light receiving signal indicating the timing at which light is detected by the PD 14. The time measuring circuit 11 measures the time between the rise timing of the light source drive signal and the rise timing of the light reception signal.

  The light receiving circuit 17 may have the same configuration as the light receiving circuit 18 shown in FIG. The light receiving circuit 17 outputs a synchronization detection signal indicating the timing at which light is detected by the PD 13.

  In the present embodiment, the light detection unit may be a light receiving element other than the PDs 13 and 14. The light detection unit may be an APD (Avalanche Photodiode) or a SPAD (Single Photon Avalanche Diode) which is a Geiger mode APD. Since APD and SPAD are more sensitive than PD, it is possible to improve the accuracy of distance measurement, and it is advantageous in that distance measurement can be performed for an object that is further away.

  The light source unit 12 includes any of an edge emitting laser, a stack type laser in which edge emitting lasers are stacked, a VCSEL (Vertical Cavity Surface Emitting Laser) that is a surface emitting laser, a VCSEL array in which VCSELs are arranged in a two-dimensional direction, and the like. May be provided.

  When the deflection angle of the deflector 30 changes within the first angle range, the optical scanning device 10 causes the light source unit 12 to emit pulses in accordance with a first drive signal that is a light source drive signal from the ECU 20. The light source unit 12 outputs pulsed light as first output light. The deflector 30 deflects the pulsed light from the light source unit 12 and advances it to the detection area AR. The PD 14 proceeds from the deflector 30 to the detection area AR, and detects the first detection light that is the first output light reflected by the object in the detection area AR.

  In addition, when the deflection angle of the deflector 30 changes within the second angle range, the optical scanning device 10 continuously emits light from the light source unit 12 according to the second drive signal that is a light source drive signal from the ECU 20. Let The light source unit 12 continuously outputs light having a constant light amount as the second output light. The PD 13 detects second detection light that is second output light that travels in a direction other than the detection area AR from the deflector 30 and travels from the mirror 33 toward the PD 13.

  8 and 9 are diagrams for describing driving of the light source unit 12 according to the first drive signal. The graph shown in the upper part of FIG. 8 represents a change in current supplied to the light source unit 12 with the vertical axis representing current and the horizontal axis representing time. The graph shown in the lower part of FIG. 8 represents a change in the light amount of the first output light with the vertical axis representing the light amount of the first output light and the horizontal axis representing the time axis. FIG. 9 shows a lighting pattern of the light source unit 12 on a time axis longer than the time axis of the graph shown in FIG.

  The light source driving circuit 16 supplies the light source unit 12 with a pulse current whose current value is changed in a rectangular wave shape according to the first driving signal. Ip is a peak current value in the pulse current, and Tp is a pulse width of the pulse current. P1 is the peak light amount of the pulsed light that is the first output light emitted from the light source unit 12, and Ton1 is the lighting time (on time) of the light source unit 12. The on-time Ton1 is a half-value width that is a time when the light amount becomes half or more of P1. In the period in which the deflection angle of the deflector 30 changes within the first angle range, the light source unit 12 repeatedly emits the pulsed light with the light amount P1 at the time interval T1, as shown in FIG.

  The optical scanning device 10 is desired to output from the light source unit 12 high-power pulsed light of several tens to 100 W level in order to enable distance measurement of an object far from the vehicle 101. In order to obtain high-power pulse light, a high current value Ip of about several tens to 100 A is supplied to the light source unit 12.

  In the specification of the light source unit 12, the on time Ton1 is predetermined. When Ip is about several tens of A, the duty ratio, which is the ratio of the light emission time to the pulse light emission interval T1, is about 0.1%. When the duty ratio is higher than about 0.1%, the life of the light source unit 12 is affected. Therefore, for example, when the on-time Ton1 is 20 ns (nanosecond) and the duty ratio is 0.1%, it is desirable that the interval T1 is longer than 20 μs (microsecond).

  In the case of pulse light emission, since the supply current to the light source unit 12 is high, a method of supplying charges stored in advance in a capacitor or the like to the light source unit 12 in a short time is widely adopted. By supplying a pulse current satisfying Tp> Ton1 to the light source unit 12, the light source unit 12 can perform stable pulse emission in a time width in which the accumulated charges are supplied.

  FIG. 10 is a diagram illustrating driving of the light source unit 12 according to the second drive signal. The graph shown in the upper part of FIG. 10 represents a change in current supplied to the light source unit 12 with the vertical axis representing current and the horizontal axis representing time. The graph shown in the lower part of FIG. 10 represents a change in the light amount of the second output light, with the vertical axis representing the light amount of the second output light and the horizontal axis representing the time axis.

  The light source drive circuit 16 supplies a current having a constant current value Is to the light source unit 12 in accordance with the second drive signal. The light source driving circuit 16 continues the current supply to the light source unit 12 at time Ts. It is assumed that the current value Is is lower than the current value Ip in pulsed light emission. P2 is a light amount of the second output light emitted from the light source unit 12, and Ton2 is a lighting time (on time) of the light source unit 12.

  The light source unit 12 continuously emits light having a constant light amount P2 during the on-time Ton2. The light quantity P2 is smaller than the peak light quantity P1 in the pulse light emission. The on-time Ton2 substantially coincides with the time Ts and is longer than the on-time Ton1 in pulsed light emission.

  Further, the on-time Ton2 substantially coincides with a period during which the deflection angle of the deflector 30 changes within the second angle range. If the light from the light source unit 12 can travel toward the PD 13 according to the rotation of the deflector 30, the on-time Ton2 is from a period during which the deflection angle of the deflector 30 changes within the second angle range. It may be long or short. As a result, the light source unit 12 continuously outputs light having a level of several mW lower than the pulsed light as the light used for generating the synchronization detection signal during the on-time Ton2.

  FIG. 11 is a diagram illustrating a lighting pattern of the light source unit 12 according to the first drive signal and the second drive signal. FIG. 11 shows a combination of a lighting pattern corresponding to the first drive signal shown in FIG. 9 and a lighting pattern corresponding to the second drive signal. The time axis of the graph shown in FIG. 11 is longer than the time axis of the graphs shown in FIGS.

  In response to the second drive signal, the light source unit 12 emits light having a light amount P2 with a time interval of T2. The interval T2 coincides with the rotation period of the deflector 30 and is longer than the interval T1 in pulse emission. The light source unit 12 repeatedly emits the pulsed light of the light amount P1 at the time interval T1 during the interval T2 during which the deflection angle of the deflector 30 changes within the first angle range. The light source drive circuit 16 stops driving the light source unit 12 according to the second drive signal during a period in which the light source unit 12 is driven according to the first drive signal. In this way, the light source unit 12 outputs the first output light used for distance measurement and the second output light used for generation of the synchronization detection signal.

  Here, a circuit configuration including the light source driving circuit 16 and the light source unit 12 in the optical scanning device 10 of the first embodiment and a circuit configuration according to a comparative example will be described. FIG. 12 is a diagram illustrating a circuit configuration included in the optical scanning device 10 according to the first embodiment. FIG. 13 is a diagram illustrating a circuit configuration according to a comparative example of the first embodiment.

  The circuit configuration of the comparative example shown in FIG. 13 includes switches SW1 and SW2, resistors R1 and Rs, a capacitor C1, and a laser diode LD1. The switch SW1, the resistor R1, and the capacitor C1 constitute a drive circuit (pulse light emission drive circuit) for pulse light emission. The switch SW2 and the resistors R1 and Rs constitute a drive circuit (synchronous light emission drive circuit) for obtaining light used for generating the synchronization detection signal. In the comparative example, the pulse light emission drive circuit and the synchronous light emission drive circuit drive LD1 using the common power supply voltage V1.

  LD1 is connected to a power supply terminal via a resistor R1. A power supply voltage V1 is applied to the power supply terminal. The switch SW1 is connected between the LD1 and the ground electrode. The resistor Rs and the switch SW2 are connected between the LD1 and the ground electrode.

  The switch SW1 is switched according to the first drive signal Vp for pulse light emission. The switch SW2 is switched according to the second drive signal Vs for obtaining light used for generating the synchronization detection signal. The period in which the switch SW1 is in the connected state and the period in which the switch SW2 is in the connected state do not overlap each other.

  The switches SW1 and SW2 include, for example, NMOS transistors. In order to operate the switches SW1 and SW2 with a desired drive current capability, the gate potential of the switches SW1 and SW2 is set to a certain voltage level or the switches SW1 and SW2 are operated using a gate driver or the like.

  When both the switches SW1 and SW2 are in a disconnected state, electric charge is accumulated in the capacitor C1. When the switch SW1 is switched from disconnection to connection, the charge of the capacitor C1 is supplied to the LD1. A common power supply voltage V1 is applied to the LD1 both during driving according to the first drive signal Vp and during driving according to the second drive signal Vs.

  The light source drive circuit 16 of the first embodiment shown in FIG. 12 includes a pulse light emission drive circuit 41 as a first light source drive unit and a synchronous light emission drive circuit 42 as a second light source drive unit. The pulse light emission drive circuit 41 is a drive circuit for pulse light emission. The synchronous light emission drive circuit 42 is a drive circuit for obtaining light used for generating a synchronization detection signal. A pulse light emission drive circuit 41 and a synchronous light emission drive circuit 42 connected in parallel to each other are connected to the light source unit 12. The light source unit 12 includes an LD 1 that is a laser diode.

  The pulse light emission drive circuit 41 includes a switch SW1 (first switch), a resistor R1, a capacitor C1 (first capacitor), and a first power supply terminal to which a power supply voltage V1 (first power supply voltage) is applied. . The pulse light emission drive circuit 41 drives the LD1 by applying the power supply voltage V1, and outputs the first output light from the LD1.

  The synchronous light emission drive circuit 42 is applied with a switch SW2 (second switch), resistors R2 and Rs, a capacitor C2 (second capacitor), and a power supply voltage V2 (second power supply voltage) different from the power supply voltage V1. A second power supply terminal. The power supply voltage V2 is smaller than the power supply voltage V1. The synchronous light emission drive circuit 42 drives the LD1 by applying the power supply voltage V2, and outputs the second output light from the LD1. The synchronous light emission drive circuit 42 drives the LD1 except during the period in which the pulse light emission drive circuit 41 drives the LD1.

  The resistor R1, the switches SW1 and LD1 are connected in series between the first power supply terminal and the ground electrode. The capacitor C1 is connected in parallel with the switches SW1 and LD1. The switch SW1 switches between connection and disconnection according to the first drive signal Vp for pulse light emission. When the switch SW1 is in a disconnected state, charges are accumulated in the capacitor C1. The resistor R1 functions as a charging resistor for charging the capacitor C1.

  The resistor R2, the switch SW2, the resistors Rs and LD1 are connected in series between the second power supply terminal and the ground electrode. The capacitor C2 is connected in parallel with the switch SW2, the resistor Rs, and LD1. The switch SW2 switches between connection and disconnection according to the second drive signal Vs for obtaining light used for generation of the synchronization detection signal. When the switch SW2 is in a disconnected state, electric charge is accumulated in the capacitor C2. The resistor R2 functions as a charging resistor for charging the capacitor C2.

  At least one of the switch SW1 and the switch SW2 is in a disconnected state when the optical scanning device 10 is in operation. The period in which the switch SW1 is in the connected state and the period in which the switch SW2 is in the connected state do not overlap each other. The switches SW1 and SW2 may be any elements that can be switched between connection and disconnection.

  When the switch SW1 is switched from disconnection to connection according to the first drive signal Vp, the pulse light emission drive circuit 41 supplies the charge accumulated in the capacitor C1 to the LD1. A current having a substantially constant current value Ip determined by the power supply voltage V1 and the capacitance of the capacitor C1 is supplied to the LD1 in the time of the pulse width Tp. Thereby, the light source part 12 inject | emits from the LD1 the pulsed light by the peak light quantity P1 and ON time Ton1 as 1st output light utilized for distance measurement.

  When the switch SW2 is switched from disconnection to connection according to the second drive signal Vs, the synchronous light emission drive circuit 42 supplies the charge accumulated in the capacitor C2 to the LD1. The resistor Rs functions as a current limiting resistor for the LD1. The LD 1 is supplied with a substantially constant current value Is determined by the power supply voltage V2, the capacitance of the capacitor C2, and the resistor Rs at time Ts. Thereby, the light source unit 12 emits continuous light of the light amount P2 which is the second output light used for generating the synchronization detection signal from the LD 2 during the on-time Ton2.

  The current value Is required for the output of light used to generate the synchronization detection signal is about 1/100 or less of the current value Ip required for the output of pulsed light. By setting the power supply voltage V2 smaller than the power supply voltage V1 of the pulse light emission drive circuit 41 to the synchronous light emission drive circuit 42, it is required for the switch SW2 and the resistors R2 and Rs which are parts constituting the synchronous light emission drive circuit 42. Withstand voltage and rated voltage are reduced.

  Since the optical scanning device 10 can use components with a low withstand voltage and a rated voltage, the degree of freedom of component selection can be increased and the cost can be reduced. In general, components with low withstand voltage are smaller in size than components with high withstand voltage, so the use of components with low withstand voltage reduces the size of the board on which the component is mounted and the module on which the substrate is mounted. it can. Further, the optical scanning device 10 can control the optical scanning with high accuracy by controlling the supply timing of the pulsed light based on the synchronization detection signal corresponding to the operation of the deflector 30. As described above, the optical scanning device 10 and the distance measuring device 100 have an effect that the optical scanning can be controlled with high accuracy and the configuration can be downsized and the manufacturing cost can be reduced.

(Second Embodiment)
FIG. 14 is a diagram illustrating a circuit configuration included in the optical scanning device 10 according to the second embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and repeated description will be omitted as appropriate.

  The optical scanning device 10 according to the second embodiment includes a light source unit 53 and a light source drive circuit 50 in place of the light source unit 12 and the light source drive circuit 16 of the first embodiment. The light source unit 53 includes two laser diodes LD1 and LD2. LD1 outputs the first output light. LD2 outputs the second output light.

  The light source drive circuit 50 includes a pulse light emission drive circuit 51 as a first light source drive unit and a synchronous light emission drive circuit 52 as a second light source drive unit. The pulse light emission drive circuit 51 includes a switch SW1, a resistor R1, a capacitor C1, and a first power supply terminal to which a power supply voltage V1 (first power supply voltage) is applied. The resistor R1, the switches SW1 and LD1 are connected in series between the first power supply terminal and the ground electrode. The pulse light emission drive circuit 51 drives the LD1 by applying the power supply voltage V1, and outputs the first output light from the LD1.

  The synchronous light emission drive circuit 52 includes a switch SW2, resistors R2 and Rs, a capacitor C2, and a second power supply terminal to which a power supply voltage V2 (second power supply voltage) different from the power supply voltage V1 is applied. The power supply voltage V2 is smaller than the power supply voltage V1. The resistor R2, the switch SW2, and the resistors Rs and LD2 are connected in series between the second power supply terminal and the ground electrode. The synchronous light emission driving circuit 52 drives the LD2 by applying the power supply voltage V2, and outputs the second output light from the LD2.

  When the switch SW1 is switched from disconnection to connection according to the first drive signal Vp, the pulse light emission drive circuit 51 supplies the charge accumulated in the capacitor C1 to the LD1. Thereby, the light source part 53 inject | emits the pulsed light which is the 1st output light utilized for distance measurement from LD1.

  When the switch SW2 is switched from disconnection to connection according to the second drive signal Vs, the synchronous light emission drive circuit 52 supplies the charge accumulated in the capacitor C2 to the LD2. Thereby, the light source part 53 inject | emits from the LD2 the continuous light which is the 2nd output light utilized for the production | generation of a synchronous detection signal.

  The light amount of the output light from the LD 2 may be as long as the detection light can be detected by the PD 13 for generating the synchronization detection signal. As the light source unit 53, an LD 2 having a lower output than that used when emitting pulsed light can be used. The optical scanning device 10 can have a smaller configuration and a lower manufacturing cost than when both the LD1 and LD2 have high output.

  Also in the second embodiment, the optical scanning device 10 and the distance measuring device 100 enable high-precision control of optical scanning, as well as downsizing and manufacturing cost, as in the first embodiment. There is an effect that reduction is possible.

(Third embodiment)
FIG. 15 is a diagram illustrating a circuit configuration included in the optical scanning device 10 according to the third embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and repeated description will be omitted as appropriate.

  The optical scanning device 10 according to the third embodiment includes a light source unit 63 and a light source drive circuit 60 in place of the light source unit 12 and the light source drive circuit 16 of the first embodiment. The light source unit 63 includes four laser diodes LD1-1 to LD1-4 that output first output light, and LD2 that is a laser diode that outputs second output light. LD1-1 to LD1-4 and LD2 are connected in parallel to each other.

  LD1-1 to LD1-4 are arranged in a direction perpendicular to the Y-axis direction, which is the light scanning direction of the optical scanning device 10. The number of laser diodes that output the first output light is not limited to four, but may be plural.

  The light source drive circuit 60 includes a pulse light emission drive circuit 61 as a first light source drive unit and a synchronous light emission drive circuit 62 as a second light source drive unit. The pulse light emission drive circuit 61 has a circuit configuration similar to that of the pulse light emission drive circuit 51 of the second embodiment for each of the LD 1-1 to LD 1-4. Each circuit configuration is connected in parallel to each other.

  The pulse light emission drive circuit 61 is supplied with switches SW1-1 to SW1-4, resistors R1-1 to R1-4, capacitors C1-1 to C1-4, and a power supply voltage V1 (first power supply voltage) 4. Two first power supply terminals. The light emission timings of the LD 1-1 to LD 1-4 can be controlled independently of each other by switching the switches SW1-1 to SW1-4. LD1-1 to LD1-4 emit pulsed light in accordance with currents of current values Ip1 to Ip4, respectively. The synchronous light emission drive circuit 62 has the same configuration as the synchronous light emission drive circuit 52 of the second embodiment.

  The optical scanning device 10 sequentially drives a plurality of light emitting elements arranged in a direction perpendicular to the scanning direction, thereby shifting the light in the direction perpendicular to the scanning direction and allowing the light to travel to the detection region AR. it can. Thereby, the optical scanning device 10 can scan the light in the two-dimensional direction by scanning the light in the scanning direction and shifting the light in the direction perpendicular to the scanning direction.

  Also in the third embodiment, the optical scanning device 10 and the distance measuring device 100 enable high-accuracy control of the optical scanning, as well as the downsizing of the configuration and the manufacturing cost, as in the first embodiment. There is an effect that reduction is possible.

(Fourth embodiment)
FIG. 16 is a diagram illustrating a circuit configuration included in the optical scanning device 10 according to the fourth embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and repeated description will be omitted as appropriate.

  The light source drive circuit 70 of the optical scanning device 10 according to the fourth embodiment includes a pulse light emission drive circuit 71 as a first light source drive unit, a synchronous light emission drive circuit 72 as a second light source drive unit, and a switch SW3. (Third switch). The switch SW3 is connected between the light source unit 12 and a ground electrode as a power supply terminal.

  The capacitor C1 of the pulse light emission drive circuit 71 is connected in parallel with the light source unit 12 and the switch SW3. The capacitor C2 of the synchronous light emission drive circuit 72 is connected in parallel with the switch SW2, the resistor Rs, the light source unit 12, and the switch SW3.

  When the switch SW1 is connected according to the first drive signal Vp and the switches SW2 and SW3 are disconnected, charge is accumulated in the capacitor C1. Thereafter, the switch SW1 is switched from connection to disconnection, and the switch SW3 is switched from disconnection to connection, whereby the charge accumulated in the capacitor C1 is supplied to the LD1.

  When the switch SW2 is connected according to the second drive signal Vs and the switches SW1 and SW3 are disconnected, charges are accumulated in the capacitor C2. Thereafter, the switch SW2 is switched from connection to disconnection, and the switch SW3 is switched from disconnection to connection, whereby the charge accumulated in the capacitor C2 is supplied to the LD1.

  The switch SW3 performs charge supply to the LD1 according to the first drive signal Vp and charge supply to the LD1 according to the second drive signal Vs, and the pulse light emission drive circuit 71, the synchronous light emission drive circuit 72, Shared by. The switches SW1 and SW2 are used for charging with the capacitors C1 and C2, respectively.

  The switches SW1 and SW2 can reduce the energization current as compared with the case of performing switching for supplying electric charges to the light source unit 12, thereby reducing the rated current required for the switches SW1 and SW2. For the light source drive circuit 70, a switch SW3 having a rated current sufficient for supplying charges to the light source unit 12 and switches SW1 and SW2 having a low rated current can be used.

  The optical scanning device 10 can have a smaller configuration and a lower manufacturing cost than the case where a switch having a high rated current is provided in each of the pulse light emission drive circuit 71 and the synchronous light emission drive circuit 72. Also in the fourth embodiment, the optical scanning device 10 and the distance measuring device 100 have an effect that the optical scanning can be controlled with high accuracy, the configuration can be downsized, and the manufacturing cost can be reduced.

(Fifth embodiment)
FIG. 17 is a diagram illustrating a circuit configuration included in the optical scanning device 10 according to the fifth embodiment. The same parts as those in the third embodiment are denoted by the same reference numerals, and repeated description is omitted as appropriate.

  The optical scanning device 10 according to the fifth embodiment includes a light source unit 83 and a light source drive circuit 80 in place of the light source unit 63 and the light source drive circuit 60 of the third embodiment. The light source unit 83 includes four laser diodes LD1-1 to LD1-4. One of them, the LD 1-1, outputs the first output light and the second output light. The other three LD1-2 to LD1-4 output the first output light. LD1-1 to LD1-4 are connected in parallel to each other.

  LD1-1 to LD1-4 are arranged in a direction perpendicular to the scanning direction of light by the optical scanning device 10, as in the third embodiment. The number of laser diodes that output the first output light is not limited to four, but may be plural. Similar to the third embodiment, the optical scanning device 10 can detect an object by scanning light in a two-dimensional direction.

  The light source drive circuit 80 includes a pulse light emission drive circuit 81 as a first light source drive unit, a synchronous light emission drive circuit 82 as a second light source drive unit, and a switch SW3. The pulse light emission drive circuit 81 has a common circuit configuration for each of the LD 1-1 to LD1-4. Each circuit configuration is connected in parallel to each other. The switch SW3 is connected between the LD1-1 to LD1-4 and the ground electrode.

  The circuit configuration corresponding to LD1-1 includes a switch SW1-1, a capacitor C1-1, and a diode D1-1. The switch SW-1, the diode D1-1, and the LD1-1 are connected in series between the resistor R1 and the switch SW3. The capacitor C1-1 is connected in parallel with the diodes D1-1, LD1-1, and the switch SW3. Each circuit configuration for LD1-2 to LD1-4 is the same as the circuit configuration for LD1-1.

  The switch SW2 and the resistor Rs of the synchronous light emission drive circuit 82 are connected in series between the resistor R2 and the diode D1-1. The capacitor C2 is connected in parallel with the resistor Rs, the diodes D1-1, LD1-1, and the switch SW3.

  When the switch SW1-1 is connected according to the first drive signal Vp and the switches SW1-2 to SW1-4, SW2 and SW3 are disconnected, the electric charge is accumulated in the capacitor C1-1. Thereafter, the switch SW1-1 is switched from connection to disconnection, and the switch SW3 is switched from disconnection to connection, whereby the charge accumulated in the capacitor C1-1 is supplied to the LD1-1. At this time, the pulse light emission drive circuit 81 supplies current to the LD 1-1 by the rectifying action of the diodes D 1-1 to D 1-4, while interrupting current supply to the LD 1-2 to LD 1-4. The pulse light emission drive circuit 81 drives LD1-2 to LD1-4 in the same manner as LD1-1. LD1-1 to LD1-4 emit pulsed light in accordance with currents of current values Ip1 to Ip4, respectively.

  When the switch SW2 is connected according to the second drive signal Vs and the switches SW1-1 to SW1-4 and SW3 are disconnected, charges are accumulated in the capacitor C2. Thereafter, the switch SW2 is switched from connection to disconnection, and the switch SW3 is switched from disconnection to connection, whereby the charge accumulated in the capacitor C2 is supplied to the LD1-1. At this time, the light source drive circuit 80 supplies the current to the LD 1-1 by the rectifying action of the diodes D1-1 to D1-4, and cuts off the current supply to the LD1-2 to LD1-4. The LD 1-1 emits second output light used for generating the synchronization detection signal in accordance with the current of the current value Is.

  The switch SW3 is responsible for charge supply to the light source unit 83 according to the first drive signal Vp and charge supply to the light source unit 83 according to the second drive signal Vs, and synchronous light emission with the pulse light emission drive circuit 81. It is shared with the drive circuit 82. Switches SW1-1 to SW1-4 and SW2 are used for charging with capacitors C1-1 to C1-4 and C2, respectively. Similar to the fourth embodiment, the light source driving circuit 80 includes a switch SW3 having a rated current sufficient for supplying charges to the LD1-1 to LD1-4 and a switch SW1-1 to SW1-1 having a low rated current. SW1-4 and SW2 can be used.

  The optical scanning device 10 can have a smaller configuration and a lower manufacturing cost than a case where a switch having a high rated current is provided for each light emitting element. Also in the fifth embodiment, the optical scanning device 10 and the distance measuring device 100 have an effect that the optical scanning can be controlled with high accuracy, the configuration can be downsized, and the manufacturing cost can be reduced.

(Sixth embodiment)
FIG. 18 is a diagram illustrating a circuit configuration included in the optical scanning device 10 according to the sixth embodiment. The same parts as those in the fifth embodiment are denoted by the same reference numerals, and redundant description will be omitted as appropriate.

  The optical scanning device 10 according to the sixth embodiment includes a light source unit 93 and a light source driving circuit 90 in place of the light source unit 83 and the light source driving circuit 80 of the fifth embodiment. The light source section 93 includes five laser diodes LD1-1 to LD1-4 and LD2. One of these, LD2, outputs the second output light. The other four LD1-1 to LD1-4 output the first output light. LD1-1 to LD1-4 and LD2 are connected in parallel to each other.

  LD1-1 to LD1-4 are arranged in a direction perpendicular to the scanning direction of light by the optical scanning device 10, as in the fifth embodiment. The number of laser diodes that output the first output light is not limited to four, but may be plural. Similar to the fifth embodiment, the optical scanning device 10 can detect an object by scanning light in a two-dimensional direction.

  The light source drive circuit 90 includes a pulse light emission drive circuit 91 as a first light source drive unit, a synchronous light emission drive circuit 92 as a second light source drive unit, and a switch SW3. The pulse light emission drive circuit 91 has the same configuration as that of the pulse drive circuit 81 of the fifth embodiment.

  The switch SW2 and the resistors Rs and LD2 are connected in series between the resistor R2 and the switch SW3. The capacitor C2 is connected in parallel with the resistors Rs, LD2 and the switch SW3.

  The pulse light emission drive circuit 91 drives the LD 1-1 to LD1-4 similarly to the pulse light emission drive circuit 81 of the fifth embodiment. When the switch SW2 is connected according to the second drive signal Vs and the switches SW1-1 to SW1-4 and SW3 are disconnected, charges are accumulated in the capacitor C2. Thereafter, the switch SW2 is switched from connection to disconnection, and the switch SW3 is switched from disconnection to connection, whereby the charge accumulated in the capacitor C2 is supplied to the LD2.

  The light amount of the output light from the LD 2 may be as long as the detection light can be detected by the PD 13 for generating the synchronization detection signal. As the light source unit 93, an LD 2 having a lower output than that used when emitting pulsed light can be used. The optical scanning device 10 can be reduced in size and can be manufactured at a lower cost than when all of the LD1-1 to LD1-4 and LD2 have high output.

  Also in the sixth embodiment, the optical scanning device 10 and the distance measuring device 100 enable high-precision control of optical scanning, as well as downsizing of the configuration and manufacturing cost, as in the first embodiment. There is an effect that reduction is possible.

(Seventh embodiment)
FIG. 19 is a diagram illustrating a circuit configuration included in the optical scanning device 10 according to the seventh embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and repeated description will be omitted as appropriate.

  In the light source driving circuit 16 of the optical scanning device 10 according to the seventh embodiment, NMOS transistors Tr1 and Tr2 are used as the switches SW1 and SW2 of the light source driving circuit 16 of the first embodiment. By using the NMOS transistors Tr1 and Tr2, the light source drive circuit 16 can realize a high-speed response according to the first drive signal Vp and the second drive signal Vs.

  In the second to sixth embodiments, an NMOS transistor may be used as a switch. Also in the seventh embodiment, the optical scanning device 10 and the distance measuring device 100 enable high-accuracy control of the optical scanning as well as the first embodiment, and the downsizing of the configuration and the manufacturing cost can be reduced. There is an effect that reduction is possible.

  The optical scanning device 10 and the distance measuring device 100 of each embodiment may be mounted on a moving body other than the vehicle 101, for example, an aircraft or a train. The optical scanning device 10 is not limited to the one used for distance measurement, and may detect an object in applications other than distance measurement. The optical scanning device 10 may be applied to a device that monitors the presence or absence of an object or a device that measures the shape of an object.

10 optical scanning device 11 time measuring circuit 12, 53, 63, 83, 93 light source unit 13, 14 PD
DESCRIPTION OF SYMBOLS 15 Optical deflection part 30 Deflector 41,51,61,71,81,91 Pulse light emission drive circuit 42,52,62,72,82,92 Synchronous light emission drive circuit 100 Distance measuring device

Japanese Patent No. 4831151

Claims (10)

An optical scanning device that scans light in a detection region,
A light source unit that outputs first output light and second output light;
A light deflector that includes a deflector that deflects the first output light and the second output light from the light source unit, and that displaces the light traveling from the deflector;
A first light detection unit that travels from the deflector to the detection region and detects first detection light that is the first output light reflected by an object in the detection region;
A second light detection unit that detects second detection light that is the second output light that has traveled in a direction other than the detection region from the deflector;
A first light source driving unit configured to drive the light source unit by applying a first power supply voltage and to output the first output light from the light source unit;
A second light source driving unit that drives the light source unit by applying a second power source voltage different from the first power source voltage and outputs the second output light from the light source unit;
An optical scanning device comprising:   The optical scanning device according to claim 1, wherein the second power supply voltage is smaller than the first power supply voltage. The first light source drive unit drives the light source unit according to a first drive signal,
The optical scanning device according to claim 1, wherein the second light source driving unit drives the light source unit according to a second driving signal.   4. The device according to claim 1, wherein the second light source driving unit drives the light source unit during a period other than a period in which the first light source driving unit drives the light source unit. Optical scanning device.   5. The optical scanning device according to claim 1, wherein the light source unit includes a light emitting element that outputs the first output light and the second output light. 6.   The said light source part is provided with the 1st light emitting element which outputs the said 1st output light, and the 2nd light emitting element which outputs the said 2nd output light, The any one of Claim 1 to 4 characterized by the above-mentioned. An optical scanning device according to claim 1. The first light source driving unit includes a first capacitor for accumulating charges supplied to the light source unit, and a first switch for switching connection and disconnection between the first capacitor and the light source unit,
The second light source driving unit includes a second capacitor for accumulating charges supplied to the light source unit, and a second switch for switching connection and disconnection between the second capacitor and the light source unit. The optical scanning device according to claim 1, wherein:   The optical scanning device according to claim 7, further comprising a third switch that switches connection and disconnection between the light source unit and a power supply terminal. The light source unit includes a plurality of light emitting elements that output the first output light,
The optical scanning device according to claim 1, wherein the first light source driving unit includes a circuit configuration that is provided for each of the light emitting elements and drives the light emitting elements. The optical scanning device according to any one of claims 1 to 9, wherein light is scanned in a detection region, and reflected light from an object in the detection region is detected;
A distance calculating unit that calculates a distance to the object using a detection result of the reflected light in the optical scanning device;

Images