JP2020008825A - Object detection device - Google Patents

Abstract

To achieve scanning for periodically varying a projection direction of laser beams in a compact and highly durable configuration.SOLUTION: An object detection device includes: a torsion spring 302 fixed to a support member; a mirror 301 fixed to one surface of the torsion spring 302; a permanent magnet 321 fixed to the other surface of the torsion spring 302 so as to straddle a virtual rotating shaft 304; a drive coil 316; and a frame yoke 312 and a top yoke 314 of a magnetic body for surrounding the drive coil 316. The mirror 301 reciprocates in response to application of a drive signal to the drive coil 316. Each of projections 314d located in edges that face an N pole 321n and an S pole 321s of the permanent magnet 321, of the top yoke 314 is positioned away from a center line 321x of the permanent magnet 321 for connecting the N pole 321n and the S pole 321s when viewing in a direction along a shaft of the drive coil 316 from one end that faces the permanent magnet 321 of the shaft of the drive coil 316.SELECTED DRAWING: Figure 8A

Description

  The present invention relates to an object detection device and an object detection method for detecting an object on an optical path of a laser beam using the laser beam. The present invention also relates to a control method, a program, a mover, and a method of manufacturing the mover.

2. Description of the Related Art Conventionally, an object detection device that irradiates a pulse of laser light to the outside and detects the laser light reflected by the object and returned, thereby detecting an object on an optical path of the laser light and a distance to the object. Are known. Such an object detection device is called a lidar (LiDAR: Light Detection and Ranging).
In recent years, riders have been used in the field of autonomous driving of automobiles. To compensate for the disadvantages of camera sensors and millimeter-wave radars with low resolution, which are susceptible to external lighting environments, and to accurately detect relatively small obstacles in the driving environment, camera sensors and millimeter-wave radars are used. And so on.

  An example of a rider that can be used in the field of automatic driving is described in, for example, Patent Document 1. According to the rider described in Patent Document 1, a near-infrared laser as a light source and a light detection element as a receiver are arranged on a substrate as a pair in accordance with the measurement angle, and in order to capture high-resolution distance information in the field of view, 32 or 64 light-receiver pairs are used. Therefore, the equipment becomes very expensive.

  An example of another rider is described in Non-Patent Document 1. The rider described in Non-Patent Document 1 rotates a polygon mirror having three surfaces with different inclination angles, and deflects the laser beam with the polygon mirror, so that the laser beam falls within a viewing angle range of 4.5 ° in the vertical direction. While projecting a laser beam, the reflected light from the object is reflected on the same surface as when the polygon mirror is projected, and is guided to a photodetector for detection.

In the rider described in Non-Patent Document 1, one light receiving element can detect reflected light from a plurality of positions in the vertical direction. However, in the rider described in Non-Patent Document 1, since a polygon mirror having a different inclination angle is used for each reflection surface, it is difficult to design the center of gravity, and there is a problem that the cost increases in this respect. Further, if the polygon mirror continues to rotate at a high speed for a long time, the bearing generates heat and wear due to friction, and there is also a problem in terms of maintainability when used for a long time.
Non-Patent Document 2 describes a rider using a rotating mirror, but this document does not provide a detailed description of the configuration of the rider.

US Patent No. 8767190

Cristiano Niclass, et al., “A100-m Range 10-Frame / s 340 × 96-Pixel Time-of-Flight DepthSensor in 0.18-μm CMOS”, IEEE JOURNAL OF SOLID-STATECIRCUITS, Institute of Electrical and Electronics Engineers, FEBRUARY 2013, VOL. 48, NO. 2, p. 559-572 Nao Shimizu, "Redundant system and LiDAR Audio are pioneers in automatic driving to realize level 3", Nikkei Automotive, Nikkei BP, September 2017, p. 22-23

  By the way, in the detection of an object by a rider, in order to detect an object having a lower light reflectance at a longer distance, the detection sensitivity of a light receiving element (light detection element) is increased so that weaker reflected light can be detected. An approach is conceivable. However, from the optical path for taking in the reflected light from the object, disturbance light also enters, so if the detection sensitivity of the light receiving element is increased, not only the reflected light from the object but also the detection signal of the disturbance light increases, There is a high possibility that the disturbance light is erroneously recognized as the reflected light from the object.

Therefore, conventionally, there have been many approaches to increase the output of a laser beam to be irradiated to increase the intensity of reflected light and relatively reduce the influence of disturbance light. However, in this approach, the apparatus becomes large and expensive to generate a high-power laser beam, and projecting a high-power laser beam on a road has safety problems.
The above-described problem of disturbance light similarly occurs when an object in only one direction is detected without assuming scanning by a laser beam.

  The present invention has been made in view of such circumstances, and when detecting reflected light incident from the outside of a laser beam emitted to the outside using a light receiving element, it is possible to easily and inexpensively generate disturbance light. The purpose is to reduce the effects.

  In order to achieve the above object, an object detection device of the present invention includes a light projecting unit that projects a laser beam to the outside, a light receiving element, a light receiving optical system that guides incident light from outside to the light receiving element, An object detection device comprising: an emission timing of a laser beam; and an object detection unit that detects a distance to an object on an optical path of the laser beam based on a timing of a light detection signal output by the light receiving element. The light receiving optical system includes a condenser lens that forms an incident light on a predetermined focal plane and an aperture disposed on the focal plane of the condenser lens.

In such an object detecting device, the divergence angle at the time of projecting the laser beam by the light projecting unit is α, the diameter of the light transmitting area of the aperture is D, the distance from the condenser lens to the aperture is d, β = Arctan (D / d), and α ≦ β is preferable.
Further, it is preferable that 1 ≦ β / α ≦ 3.
Further, the light receiving element may be a silicon photomultiplier (SiPM), and light passing through the condenser lens may be incident on the entire light receiving surface of the silicon photomultiplier.
Further, a light diffusing member may be provided between the aperture and the light receiving element.

  The object detecting unit further includes a scanning unit that periodically changes a direction in which the laser beam is projected by the light emitting unit. The object detecting unit includes a light emitting timing and a light emitting direction of the laser beam. The distance to the object on the optical path of the laser beam and the direction in which the object is located may be detected based on the timing of the detection signal.

  In the object detection method of the present invention, a laser beam is projected to the outside, an incident light from the outside is formed on a predetermined focal plane by a condenser lens, and the laser beam is arranged on the focal plane of the condenser lens. By the aperture, the light condensed by the condensing lens is stopped down, the light passing through the aperture is made incident on a light receiving element, the timing of projecting the laser beam, and the timing of a light detection signal output by the light receiving element. Is used to detect the distance to the object on the optical path of the laser beam.

  The present invention also provides another object detection device, a control method thereof, and a program for realizing scanning for periodically changing the projection direction of a laser beam with a small and highly durable configuration. I do.

  The object detection device includes a light projecting unit that projects a laser beam to the outside, a scanning unit that periodically changes the direction in which the laser beam is projected by the light projecting unit, a light receiving element, and a light receiving element. Based on the light receiving optical system leading to the light receiving element, the light emitting timing and the light emitting direction of the laser beam, and the timing of the light detection signal output by the light receiving element, the distance to the object on the optical path of the laser beam and An object detection device comprising: an object detection unit that detects a direction of the object, wherein the scanning unit is a torsion spring formed of a plate having a fold, and a linear shape formed by the fold. A torsion spring fixed to a support member, a mirror fixed to one surface of the torsion spring and reflecting the laser beam, and a torsion spring other than the torsion spring so as to straddle the protrusion. A permanent magnet having an N pole on one side and an S pole on the other side, and a drive coil disposed on the opposite side of the permanent magnet from the torsion spring; A sensing coil having a common core material with the drive coil, a magnetic body surrounding the drive coil, and a drive unit that applies a drive signal that periodically changes voltage or current to the drive coil; and the mirror includes: It reciprocates in response to the application of the drive signal.

In such an object detection device, it is preferable that the cross-sectional shape of the protrusion is V-shaped.
Further, it is preferable that one end of the shaft of the drive coil faces an intermediate point between the S pole and the N pole of the permanent magnet.
Further, an end of the magnetic body facing the N-pole and the S-pole of the permanent magnet is configured such that the N-pole is viewed from one end of the drive coil shaft facing the permanent magnet in a direction along the axis. The permanent magnet is preferably located at a position distant from the center line of the permanent magnet connecting the S magnet and the S pole.
A detecting unit for detecting a voltage or a current generated in the sensing coil; and a period for controlling a blinking period of the laser beam emitted by the light emitting unit according to a level of the voltage or the current detected by the detecting unit. And a control unit.
Further, the cycle control unit may be configured to, when the level of the voltage or current detected by the detection unit is a first level indicating that the mirror is near the center of the path of the reciprocating drive, cause the mirror to reciprocate. It is preferable to shorten the blinking cycle as compared with the case where the second level indicates that it is near the end of the driving path.

Further, a control method of the present invention is a control method for controlling any one of the object detection devices described above, wherein the voltage or current generated in the sensing coil is detected, and the voltage or current is detected in accordance with the level of the detected voltage or current. , For controlling the blinking cycle of the laser beam emitted by the light emitting section.
In such a control method, according to the level of the voltage or the current generated in the sensing coil, the level of the voltage or the current is a first level indicating that the mirror is near the center of the path of the reciprocating drive. In some cases, the blinking cycle of the laser beam may be controlled such that the blinking cycle is shorter than when the mirror is at a second level indicating that the mirror is near the end of the reciprocating drive path. .
Further, a program according to the present invention is a program for causing a processor to control hardware to execute any of the control methods described above.

  Another object of the present invention is to realize a mover having a reciprocally driven mirror, which can be used for scanning for periodically changing the projection direction of a laser beam, with a configuration that can be mass-produced at low cost. And a method for manufacturing the same.

The mover is a torsion spring formed of a plate material having a fold. The mover includes a linear protrusion formed by the fold, and the protrusion formed so as to straddle the protrusion near the center of the protrusion. A torsion spring including a flat portion integrally formed with the portion, a first spacer fixed to a first surface of the flat portion on a side where the protrusion projects, and a first spacer having the same height as the protrusion; A first member fixed to a side of the first spacer opposite to the flat portion; and a second member fixed to a second surface of the flat portion opposite to the first surface. One of the member and the second member is a mirror, and the other is a magnet. The magnet is fixed so as to straddle the protrusion, and has an N pole on one side and an S pole on the other side across the protrusion. Is located.
Such a mover may have a second spacer between the plane portion and the second member, and the second member may be fixed to the plane portion via the second spacer.

  Further, the method of manufacturing the mover is a torsion spring formed of a plate material having a fold, wherein the linear protrusion formed by the fold is provided so as to straddle the protrusion near the center of the protrusion. A first spacer having the same height as the protrusion is provided on the first surface of the torsion spring including the protrusion and the flat portion integrally formed on the side of the flat portion where the protrusion protrudes. A first step of fixing by bonding or pressing so that the fixing can be maintained even during the heat treatment of the third step, and an adhesive layer that is melted by heating on the first spacer after the first step. A second step of laminating the first member and forming a laminate by laminating the second member on the second surface of the flat portion opposite to the first surface via an adhesive layer that is melted by heating. One of the first member and the second member is a mirror, and the other is a mirror. A second step in which the magnet is straddled so as to straddle the protrusion and to have an N pole on one side and an S pole on the other side across the protrusion; A heat treatment of the formed laminate to fix the first member to the first spacer and the third step of fixing the second member to the plane portion.

  In such a method for manufacturing a mover, in the first step, the second spacer can be fixed to the second surface of the flat portion by bonding or pressure bonding even during the heat treatment in the third step. And fixing the second member on the surface of the second spacer opposite to the plane portion via an adhesive layer that is melted by the heating. In the third step, the second member may be fixed to the flat portion via the second spacer.

  Further, a plurality of the torsion springs and the first spacers are provided in a state of being connected to each other and arranged in a plane, and in the first step, the plurality of torsion springs and the plurality of the first spacers are provided. Are collectively fixed in a connected state, and in the second step, the laminate is formed for each of the plurality of torsion springs. In the third step, the laminate is collectively attached to the plurality of laminates. Then, the above heat treatment may be performed to form a plurality of connected movers.

  Alternatively, a plurality of the torsion springs, the first spacers, and the second spacers are provided in a state of being connected to each other and arranged in a plane, and in the first step, the plurality of torsion springs and the second spacer are provided. The plurality of first spacers and the plurality of second spacers are collectively fixed in a connected state, and in the second step, the laminate is formed for each of the plurality of torsion springs. In the third step, the heat treatment may be performed on the plurality of stacked bodies at a time to form a plurality of connected movers.

  The invention described above as an apparatus, a method, a program, or the like can be embodied not only in the above-described embodiment, but also in any embodiment such as an apparatus, a system, a method, a program, and a recording medium on which the program is recorded.

  According to the configuration of the present invention as described above, it is possible to easily and inexpensively reduce the influence of disturbance light when detecting reflected light incident from the outside of a laser beam projected outside using a light receiving element. Can be.

FIG. 1 is a block diagram showing main components of an object detection device 10 according to an embodiment of the present invention, which are divided and focused on their functions. FIG. 2 is a diagram for explaining the principle of object detection in the object detection device 10. FIG. 2 is an exploded perspective view illustrating a structure of main components of the object detection device 10. FIG. 2 is a perspective view illustrating an appearance of the object detection device 10. FIG. 4 is a diagram showing a schematic appearance and arrangement of actuators 300 and 380 in an enlarged manner from FIG. 3. FIG. 4 is an exploded perspective view schematically illustrating the structure of components constituting an actuator 300 and an outline of an assembling process thereof. FIG. 3 is an exploded perspective view showing a structure of a part constituting a mover 320 of an actuator 300. FIG. 7 is a cross-sectional view taken along a direction indicated by an arrow M in a plane indicated by a chain line of the actuator 300 shown in FIG. FIG. 8B is a cross-sectional view illustrating a configuration of a modification of the actuator 300 and corresponding to FIG. 8A. FIG. 9 is an exploded perspective view schematically showing a structure of components constituting a mover 330 and an assembling process thereof. FIG. 10 is a cross-sectional view of a cross section of the mover 330 shown in FIG. It is a figure which shows the example of the laminated body which laminated | stacked and fixed the torsion spring 331, the 1st spacer 332, and the 2nd spacer 333 in the state respectively each connected and planarly arranged. 6 is a graph showing a relationship between a scanning angle of a mirror 301 and an absolute value of a scanning angular velocity. FIG. 3 is a diagram illustrating an example of a drive signal of an LD module 21. FIG. 14 is a diagram illustrating an example of a spot formed by emission light L2 formed on a scanning line when the drive signal in FIG. 13 is used. FIG. 3 is a diagram illustrating a configuration of a control circuit for controlling an interval between pulses of a drive signal of an LD module 21 together with peripheral circuits. FIG. 16 is a diagram illustrating an example of a drive signal of the LD module 21 generated by the circuit of FIG. FIG. 17 is a diagram illustrating an example of a spot formed by emission light L2 formed on a scanning line when the drive signal of FIG. 16 is used. FIG. 3 is a diagram schematically illustrating an optical path of a laser beam emitted from a light emitting unit. FIG. 6 is a diagram illustrating an optical path of the return light L4 condensed by the condenser lens 42 when there is no aperture 44. FIG. 4 is a diagram illustrating an optical path of the return light L4 condensed by the condenser lens 42 when an aperture 44 is provided. FIG. 3 is a diagram illustrating an arrangement of a light transmitting area of an aperture 44. FIG. 4 is a diagram for describing an effect of an aperture 44. FIG. 9 is another diagram for describing the effect of the aperture 44. FIG. 21 is a diagram corresponding to FIG. 20 and illustrating an optical path of the return light L4 condensed by the condenser lens 42 when the light diffusing member 46 is provided.

An embodiment of the present invention will be described with reference to the drawings.
[1. Overall configuration of object detection device (FIGS. 1 to 4)]
First, an overall configuration of an object detection device according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the main components of the object detection device, which are divided and focused on their functions. FIG. 2 is a diagram for explaining the principle of object detection in the object detection device.

  An object detection apparatus 10 according to an embodiment of the present invention emits a laser beam to the outside, detects a laser beam reflected and returned by an external object, and detects the light emission timing and the reflected light detection timing. Is a device that detects the distance to an object on the optical path of the laser beam and the direction in which the object is located, based on the difference between As shown in FIG. 1, the object detecting device 10 includes a light projecting unit 20, a scanning unit 30, a light receiving unit 40, a front end circuit 51, a TDC (Time-to-Digital Converter) 52, a processor. 53 and an input / output unit 54.

The light projecting unit 20 is a module for projecting a laser beam to the outside, and includes an LD (laser diode) module 21, a laser driving circuit 22, and a light projecting optical system 23.
The LD module 21 is a light emitting unit that outputs a laser beam according to a drive signal applied from the laser drive circuit 22. Here, a device having a plurality of light emitting points is used to increase the output intensity, but the number of light emitting points may be one. Although there is no particular limitation on the wavelength of the laser light, it is conceivable to use, for example, near infrared laser light.
The laser drive circuit 22 is a circuit for generating a drive signal for turning on the LD module 21 at a timing according to a parameter supplied from the processor 53 and applying the drive signal to the LD module 21. The lighting of the LD module 21 is performed intermittently by a pulse wave.

The light projecting optical system 23 is an optical system for converting the laser light output from the LD module 21 into a parallel light beam. In this embodiment, the focal point is located at the center of a plurality of light emitting points of the LD module 21. A collimating lens using a convex lens is used.
The laser beam L1 formed by the light projecting optical system 23 passes through the through hole 41a of the mirror 41 of the light receiving unit, is reflected by the mirror 31 of the scanning unit 30, and is emitted outside the object detection device 10 as emitted light L2. Output to

  Next, the scanning unit 30 is a module for deflecting the laser beam output from the light projecting unit 20 to scan within a predetermined field of view (FOV) 70, and an actuator 32 having a mirror 31. Is provided. The actuator 32 periodically changes the direction of projection of the laser beam by periodically changing the direction of the mirror 31 provided on the optical path of the laser beam.

Although only one actuator 32 is shown in FIG. 1, the actuator 32 is actually composed of two actuators 300 and 380 that swing the mirror about different axes as shown in FIGS. Is done. The actuator 300 forms a main scanning direction (Horizontal) scanning line 71a in charge of scanning in the main scanning direction, and the actuator 380 changes the direction of the mirror at the end of the scanning in the main scanning direction, and performs sub-scanning. A direction (Vertical) scanning line 71b is formed, and a scanning position in the sub-scanning direction is adjusted.
Since the LD module 21 is intermittently turned on, the scanning lines 71 are not a continuous line but a set of beam spots.

  Next, the light receiving unit 40 is a module for detecting light incident from the outside of the object detection device 10 and includes a mirror 41, a condenser lens 42, a light receiving element 43, and an aperture 44. The light to be detected by the light receiving unit 40 is a laser beam projected from the object detection device 10, reflected by an external object, and returned. The laser beam is irregularly reflected on the object surface, and only the component reflected in the direction opposite to the optical path at the time of light projection returns to the object detection device 10 as return light L3. The return light L3 travels in the opposite direction along substantially the same path as the output light L2, and reaches the mirror 41 as return light L4.

  The mirror 41 is a fixed mirror having a through hole 41 a for passing the laser beam output from the light projecting unit 20 and guiding the return light L <b> 4 to the light receiving element 43. At the position of the mirror 41, the return light L4 spreads more than the laser beam L1, so that a component that hits the mirror 41 in a wider range than the through-hole 41a and is reflected toward the light receiving element 43 at a position other than the through-hole 41a. Is done.

The condenser lens 42 is a lens that collects the return light L4 reflected by the mirror 41 and forms an image on a predetermined focal plane.
The light receiving element 43 is a light detecting element that outputs a detection signal according to the intensity of light that has hit a predetermined light receiving surface. In this embodiment, a silicon photomultiplier (SiPM) is used as a light receiving element. This will be described in detail later.
The aperture 44 is disposed on the focal plane of the condenser lens 42 and blocks light other than the opening. The detailed configuration of the aperture 44 and its significance will also be described later.
Of the above, the mirror 41, the condenser lens 42, and the aperture 44 constitute a light receiving optical system.

Next, the front end circuit 51 is a circuit that shapes the detection signal output from the light receiving element 43 into a waveform suitable for timing detection by the TDC 52.
The TDC 52 determines the timing t0 of the lighting pulse of the laser beam L1, which is the emitted light, based on the drive signal supplied from the laser drive circuit 22 and the shaped detection signal supplied from the front end circuit 51. This is a circuit for forming a digital output indicating a time difference from the timing t1 of the pulse of the returning light L4.

  Since there is a time difference between the pulse of the emitted light and the pulse of the return light, the time required for the light to reach the object on the optical path and return, the object detection is performed based on the time difference Δt as shown in FIG. The distance s from the device 10 to the object can be determined as s = c (Δt) / 2. c is the speed of light. Note that s is exactly the optical path length from the object to the light receiving element 43.

  The processor 53 is a control unit that controls the operation of each unit illustrated in FIG. It may be configured by a general-purpose computer that includes a CPU, a ROM, a RAM, and the like and executes software, may be configured by dedicated hardware, or may be a combination thereof. The processor 53 calculates, for example, the distance to the object based on the output signal from the TDC 52, and calculates the direction of the object based on the scanning timing (the projection direction of the emitted light L2) by the scanning unit 30 when the return light is detected. I do. In addition, as will be described in detail later, the lighting interval of the LD module 21 is controlled according to the direction of the mirror 31 in the scanning unit 30.

  The input / output unit 54 is a module that inputs and outputs information to and from the outside. Information input / output here includes wired or wireless communication with external devices, reception of user operations using buttons, touch panels, etc., and use of displays, lamps, speakers, vibrators, etc. Including presentation of information to The information to be output to the outside by the input / output unit 54 includes, for example, information on the detected object (even in the case of raw data of the distance and direction, it indicates that the object of a predetermined size, position, moving speed, etc. is detected based on the data. The information may be information on the operation state or the setting state of the object detection device 10. As information that the input / output unit 54 should receive from the outside, for example, information on the setting of the operation of the object detection device 10 can be considered.

As a communication partner of the input / output unit 54, for example, an automobile equipped with an automatic driving system can be considered. If the information of the object detected by the object detection device 10 is supplied to the automatic driving system, the automatic driving system can plan a traveling route that avoids the detected object by referring to the information.
It is also conceivable to implement the present invention as a system including the object detection device 10 and a device such as a car, a drone, or an aircraft with which the object detection device 10 communicates.

Next, a schematic structure of the object detection device 10 will be described with reference to FIGS. FIG. 3 is an exploded perspective view showing the structure of main components of the object detection device, and FIG. 4 is a perspective view showing the appearance of the object detection device.
As shown in FIGS. 3 and 4, the object detection device 10 includes an exterior in which a top cover 61 and a rear cover 62 are connected by two cover clips 63, 63. The top cover 61 has a window through which the emitted light L2 passes, and a transparent protective material 64 at the wavelength of the emitted light L2 is fitted in the window to prevent intrusion of dust.

The components shown in FIG. 1 are stored inside these housings. Note that the actuator 32 shown in FIG. 1 is shown as two actuators, an actuator 300 that is responsible for scanning in the main scanning direction and an actuator 380 that is responsible for scanning in the sub-scanning direction. The mirror 301 is a mirror included in the actuator 300.
Although not shown in FIG. 1, the mirror 48 is an optical element between the mirror 41 and the condenser lens 42 for changing the direction of the return light L4. A dashed line 65 indicates the field of view of the object detection device 10 (scanning range with the emitted light L2), and corresponds to the field of view 70 in FIG. Wiring between circuits such as the laser driving circuit 22 and the processor 53 and wiring between modules are not shown in FIG.
The overall configuration has been described above, and some components of the object detection device 10 will be individually described below.

[2. Oscillating actuator using torsion spring (FIGS. 5 to 8B)]
Although it has already been described that the scanning unit 30 includes the actuators 300 and 380, the actuator 300 among them has a characteristic configuration, and this point will be described next.
FIG. 5 shows a schematic appearance and arrangement of the actuators 300 and 380 in an enlarged manner from FIG.

As shown in FIG. 5, the actuator 300 and the actuator 380 have greatly different configurations.
Since the actuator 380 is used for deflecting the emitted light L2 in the sub-scanning direction, so high-speed movement is not required, an actuator of a type that rotates the mirror about a physical axis is used. The actuator 380 has a configuration in which a mirror 381 is fixed to a shaft 382, and the shaft 382 is inserted into a holder 383 so as to be rotatable. Then, by the action of the permanent magnet and the coil disposed on the back side of the mirror 381, the mirror 381 rotates about the center of the shaft 382 as the rotation shaft 384 according to the voltage applied to the coil, and reciprocates within a predetermined angle range. I do. By adjusting the intensity of the voltage, it is also possible to stop the mirror at a desired angle within the range of motion.
Such an actuator is called a galvanomirror. In general, a configuration in which a mirror attached to the other end of the shaft is rotated by applying a force to one end of the shaft is widely used. However, even at the same position in the longitudinal direction of the shaft, driving based on the same principle is possible.

  On the other hand, since the actuator 300 is used for deflecting the emitted light L2 in the main scanning direction, high-speed movement is required, and durability that can keep the high-speed movement for a long time is also required. Therefore, a novel actuator suitable for such a purpose is used as the actuator 300.

  The specific configuration will be described in detail with reference to FIGS. 6 to 8A. In general, however, the actuator 300 includes a mirror 301 and a projection formed on one surface of a torsion spring 302 having a linear projection. The torsion spring 302 is fixed so as to be straddled, and the end of the torsion spring 302 is fixed to a top yoke 314 as a support member. Then, by the action of the permanent magnet and the coil arranged on the other surface side of the torsion spring 302, the torsion spring 302 and the mirror 301 are moved to approximately the center of the projection of the torsion spring 302 in accordance with the voltage applied to the coil. It rotates around the rotating shaft 304 located, and reciprocates within a predetermined angular range.

The scanning unit 30 reflects the laser beam L1 by the mirrors 301 and 381 driven by the actuators 300 and 380, and deflects the laser beam L1 so that the emitted light L2 that scans the scanning line 71 shown in FIG. Can be projected to
It should be noted that, of course, the use of an actuator having the same structure as the actuator 300 as the actuator that performs deflection scanning in the sub-scanning direction is not hindered.

  Next, the structure and operation principle of the actuator 300 will be described in more detail with reference to FIGS. 6 to 8A. FIG. 6 is an exploded perspective view schematically showing the structure of components constituting the actuator 300 and an assembling process thereof, and also includes a perspective view of the actuator 300 completed in the final process. FIG. 7 is an exploded perspective view showing the structure of the components constituting the mover 320 of the actuator 300. FIG. 8A is a cross-sectional view of the cross section taken along the dashed line of the actuator 300 shown in FIG. However, the coil assembly 313 is not shown in FIG. 8A, and the way of winding the coil is schematically shown in FIG.

As shown in FIG. 6A, the actuator 300 includes a core yoke 311, a frame yoke 312, a coil assembly 313, a top yoke 314, and a mover 320.
Of these, the frame yoke 312 and the top yoke 314 form a magnetic sheath surrounding the coil. The frame yoke 312 and the top yoke 314 are fixed so as to hold the coil assembly 313 therein by four screws 315 penetrating four sets of screw holes 312b and 314b.

The coil assembly 313 is formed by winding a drive coil 316 and a detection coil 317 shown in FIG. 8A around a bobbin 313a made of a non-magnetic material, and covering the outside thereof with a protective cover 313c. Inside the bobbin 313a, an insertion hole 313b for passing the core portion 311a is provided. In addition, the protective cover 313c includes a terminal for applying a drive signal to the drive coil 316 and a terminal for outputting a signal generated in the sensing coil 317, at positions not covered by the exterior.
The core yoke 311 includes a core portion 311a made of a ferromagnetic material and serving as a core of the drive coil 316 and the sensing coil 317.

  As shown in FIG. 6B, these components are inserted into the insertion hole 312a of the frame yoke 312 by inserting the core portion 311a of the core yoke 311 into the insertion hole 313b of the coil assembly 313 as shown in FIG. The coil assembly 313 is positioned by inserting the core portion 311a, and then the top yoke 314 and the frame yoke 312 are fixed by screws 314 and integrated as shown in FIG.

At this time, the core part 311a is fixed to the frame yoke 312 in the steps (a) to (b), and the coil assembly 313 is fixed to the core part 311a (and the frame yoke 312) in the steps (b) to (c). Fix it. This fixing is performed by using screws, welding, or bonding (not shown), by inserting the member on the insertion side slightly larger than the space on the receiving side and pressing it into the receiving position, or by a combination thereof. It is possible to do.
6B and 6C, illustration of the mover 320 is omitted due to space limitations.

Further, as shown in FIG. 7, the mover 320 includes a permanent magnet 321 and a connection holder 323 in addition to the mirror 301 and the torsion spring 302.
Of these, the torsion spring 302 is a spring formed by bending a metal plate by press working or folding work, and has a linear projection 302c having a V-shaped cross section due to the fold. In the vicinity of the center of the protrusion 302c, a flat portion 302b protruding on both sides so as to straddle the protrusion 302c is provided. On both ends of the protrusion 302c, a flat portion protruding on both sides so as to straddle the protrusion 302c, respectively. 302a. The projecting portion 302c and the flat portions 302a and 302b are all integral with each other, and by forming a single plate-shaped member to bend these portions, the torsion spring 302 having sufficient strength can be formed at low cost. Can be formed.

Further, the plane portions 302a and 302b at both ends are all located on the same plane in a natural state. However, when a rotating force about the protrusion 302c is applied to the flat portion 302b while the flat portions 302a at both ends are fixed on the same plane, the protrusion 302c is twisted, and the flat portion 302b is centered on the protrusion 302c. Rotate to move. When the application of the force is stopped, the torsion of the protrusion 302c is eliminated by the restoring force of the spring, and the flat portion 302b returns to the same plane as the flat portion 302a.
The permanent magnet 321 is fixed to a surface of the flat portion 302b opposite to the protrusion 302c so that the N pole 321n is located on one side and the S pole 321s is located on the other side across the protrusion. The positions of the north pole 321n and the south pole 321s may be opposite to those shown in the figure without any problem.

The fixing between the permanent magnet 321 and the flat portion 302b is performed by sandwiching the permanent magnet 321 and the flat portion 302b from outside with the connection holder 323 as shown in FIG. 8A. Then, the connection holder 323, the permanent magnet 321 and the flat portion 302b are fixed to each other by bonding or the like. It is also conceivable to use an elastic connection holder 323 and fix the connection holder 323 by its elastic force. These combinations may be used. It is also conceivable to form the resin-made connection holder 323 on the torsion spring 302 integrally with the torsion spring 302 by outsert molding.
FIG. 8A is a cross-sectional view of a plane that passes through the vicinity of the center of the plane portion 302b and is perpendicular to the longitudinal direction of the protrusion 302c.

The mirror 301 is fixed to the surface of the connection holder 323 on the side opposite to the plane portion 302b. This fixing is performed by bonding. Although any adhesive may be used, an adhesive having a small curing shrinkage is desirable.
The above-described mover 320 is fixed to the mover holder 314a of the top yoke 314 in a step between (c) and (d) of FIG. 6 after assembling the members shown in FIG. 7 in advance. I do. This fixing is performed by screwing the flat portion 302a to the mover holding portion 314a with a screw (not shown), by bonding or welding the flat portion 302a and the mover holding portion 314a, or by fixing the flat portion 302a to the mover holding portion 314a. This can be performed by an arbitrary method, such as by inserting the slit 302a into a slit provided in the mover holder 314a.

  When the mover 320 is fixed to the top yoke 314, the flat portion 302b of the torsion spring 302 and the permanent magnet 321 face the coil assembly 313 through the opening 314c of the top yoke 314. More specifically, as shown in FIG. 8A, one end of a shaft of a drive coil 316 provided in the coil assembly 313 faces an intermediate point between the N pole 321n and the S pole 321s of the permanent magnet 321. When viewed from the permanent magnet 321, the drive coil 316 is disposed on the side opposite to the torsion spring 302.

In this state, the drive coil 316 is energized, and, for example, when the end on the side facing the permanent magnet 321 becomes the N pole, the S pole 321s of the permanent magnet 321 is drawn to the drive coil 316, and the N pole 321n is connected to the drive coil 316. 8A, a force is applied to the permanent magnet 321 to rotate clockwise as viewed in FIG. 8A. The force is transmitted to the flat portion 302b of the torsion spring 302, and the torsion spring 302 is rotated clockwise around a virtual rotation axis 304 near the center of the cross section of the protrusion 302c and twisted. Accordingly, the mirror 301 fixed to the plane portion 302b also rotates clockwise about the rotation axis 304.
Then, the rotation stops at a position where the magnetic force generated between the drive coil 316 and the permanent magnet 321 and the restoring force of the torsion spring 302 are balanced. By changing the intensity of the current flowing through the drive coil 316, the rotation speed and the stop position can be adjusted.

  Next, in a state where the permanent magnet 321 and the mirror 301 are rotated clockwise to an appropriate position, when the direction of current supply to the drive coil 316 is reversed, the end on the side facing the permanent magnet 321 becomes the S pole, This time, the N pole 321n of the permanent magnet 321 is attracted to the drive coil 316, the S pole 321s repels the drive coil 316, and the permanent magnet 321 receives a force to rotate counterclockwise as viewed in FIG. 8A. . The force is transmitted to the flat portion 302b of the torsion spring 302 as in the clockwise case, and the torsion spring 302 rotates counterclockwise about the rotation shaft 304 and twists in the opposite direction. Accordingly, the mirror 301 fixed to the plane portion 302b also rotates counterclockwise about the rotation axis 304.

  By periodically inverting the direction of the voltage or current of the drive signal applied to the drive coil 316, the mirror 301 alternately performs the above clockwise and counterclockwise rotations as indicated by the arrow V, A reciprocating motion that rotates around 304 in a predetermined angle range can be performed. That is, the mirror 301 can be swung on a predetermined moving path. Thus, the periodic deflection of the laser beam L1 required for scanning in the main scanning direction described with reference to FIG. 1 can be realized.

  In consideration of the life of the torsion spring 302, it is desirable that the range of the swing is symmetric with respect to the natural state. But this is not required. For example, by periodically switching on and off the voltage applied to the drive coil 316, it is possible to perform a swing in a predetermined range with a position near a natural state as one end. By periodically changing the voltage or current applied to the drive coil 316 within an appropriate range, the mirror 301 can be swung in an arbitrary swing range within the movable range of the torsion spring 302.

In any case, in the actuator 300, the end of the mover 320 is fixed to the top yoke 314, but the portion near the plane portion 302 b where the mover 320 actually moves floats in the air. No friction is generated, and heat and abrasion hardly occur even when used continuously for a long time. Therefore, high durability can be obtained.
In addition, since the coil assembly 313 is surrounded by the magnetic top yoke 314 and the frame yoke 312, leakage of magnetic force generated in the drive coil 316 can be prevented, and high drive efficiency can be obtained. However, it is not essential to provide such a surrounding of the magnetic body.

As shown in FIGS. 6 and 8A, the mover holding portion 314a of the top yoke 314 is thinner than other portions of the top yoke 314. This is because the permanent magnet 321 is positioned inside the exterior including the top yoke and the frame yoke 312, and transmits the magnetic force generated in the drive coil 316 to the permanent magnet 321 without leaking.
In order to prevent the magnetic force generated in the drive coil 316 from leaking, one end of the outer surface of the magnetic material facing the N pole 321n and the S pole 321s of the permanent magnet 321 faces the permanent magnet 321 on the axis of the drive coil 316. 8A, a position distant from the center line (indicated by reference numeral 321x in FIG. 8A) of the permanent magnet 321 connecting the N pole 321n and the S pole 321s when viewed in a direction along the axis (vertical direction in FIG. 8A). Good.

  In this embodiment, the above-described magnetic force is provided by providing the opening 314c of the top yoke 314 with a protrusion 314d extending from both sides toward the mover 320 and away from the drive coil 316 (upward in FIG. 8A). The structure is realized to prevent leakage. With this structure, a large rotational moment can be given from the drive coil 316 to the mover 320, and the swing speed of the mirror 301 can be increased and / or the power consumption can be reduced.

When the mover holding portion 314a is thin as shown in FIG. 8A, the mirror 301 comes close to the top yoke 314, so that the movable range of the mirror 301 may be restricted by interference between the mirror 301 and the top yoke 314. There is.
In order to deal with this point, as shown in FIG. 8B, it is conceivable to make the mover holding portion 314a thicker than other portions and separate the mirror 301 from the top yoke 314. In this configuration, the permanent magnet 321 may protrude outside the top yoke 314, which may cause magnetic force leakage. However, even in this case, as shown in FIG. 8B, if the protrusion 314d is formed so that its end is located above the center line 321x in the figure, magnetic leakage is prevented, and the swing speed is reduced. Higher speed and / or lower power consumption can be achieved.

The material of the torsion spring 302 may be, for example, stainless steel or phosphor bronze, but any other material that can form an elastic spring may be used. The reason why the cross section of the protrusion 302c is V-shaped is that it has been found by the simulations of the inventors that a large spring constant is obtained, and that the resonance frequency of the torsion spring 302 can be increased. is there. When the resonance frequency is high, a large scanning angle can be realized with a smaller driving power, which is desirable.
However, the shape of the cross section is not limited to the V-shape, and as long as it can function as a torsion spring, the n-shape or U-shape whose cross section is angular, or the M-shape, W-shape, or opening shape Other shapes, such as no air core thin wall closed cross section, may be used.

Note that the structure having such a linear projection 302c can increase the rigidity in the direction perpendicular to the rotation axis as compared with a planar structure torsion spring. This rigidity is very useful for performing stable scanning in an environment that constantly vibrates, such as in an automobile, and for ensuring the durability of the swinging part.
Further, the torsion spring having the protrusion 302c has a three-dimensional shape and a large overall thickness. Therefore, it is easy to bend the plate material, but it is not possible to form a torsion spring having a sufficiently high protrusion 302c by a wafer process using MEMS (Micro Electro Mechanical Systems) technology. ,Have difficulty.

  In the example of FIG. 8A, the drive coil 316 is arranged in a natural state in a direction perpendicular to the plane portion 302b, but one end of the shaft is connected to an intermediate point between the N pole 321n and the S pole 321s of the permanent magnet 321. The direction is not limited to that shown in FIG. 8A. For example, even if the shaft is arranged in parallel with the protrusion 302c, the mirror 301 can swing as in the configuration of FIG. 8A.

Further, it is not essential that the drive coil 316 be housed in the coil assembly 313 or wound on a bobbin, and it is not impeded that the drive coil 316 is wound directly on the core portion 311a.
The sensing coil 317 is provided for adjusting the lighting timing of the laser beam L1, which will be described later with reference to FIGS. 9 to 15, and is unnecessary if this adjustment is not performed.

8A and 8B, the protrusion 302c of the torsion spring 302 protrudes toward the mirror 301, but may protrude toward the permanent magnet 321. That is, the permanent magnet 321 may be provided on the surface of the flat portion 302b on the side where the protrusion 302c projects, via a holder similar to the connection holder 323, and the mirror 301 may be provided on the opposite surface. Also in this configuration, similarly to the configuration described with reference to FIGS. 8A and 8B, the mirror 301 can be swung about the rotation axis located substantially at the center of the protrusion 302 c.
In addition to the above, it is not hindered to use an electromagnet that is energized when the mirror is driven instead of the permanent magnet 321. However, the permanent magnet 321 is preferable because it has a simple structure, does not easily cause an assembly error, and does not generate unnecessary noise.

[3. Another configuration example of the mover included in the swing actuator and a method of manufacturing the same (FIGS. 9 to 11)]
Next, another configuration example of the mover that can be used in the above-described actuator 300 and a manufacturing method thereof will be described. The mover 330 described in this section has a configuration suitable for mass production.

FIG. 9 is an exploded perspective view schematically showing the structure of parts constituting the mover 330 and an assembling process thereof, and also includes a perspective view of the mover 330 completed in the final step. FIG. 10 is a cross-sectional view of the cross section of the mover 330 shown in FIG.
The mover 330 includes a torsion spring 331, a first spacer 332, a second spacer 333, a mirror 301, and a permanent magnet 321 as shown in FIG. The mirror 301 and the permanent magnet 321 are equivalent to those constituting the mover 320 shown in FIG.

  The torsion spring 331 also includes a flat portion 331b and a protrusion 331c similar to the torsion spring 302 constituting the mover 320. However, the flat portions 331a provided at both ends of the protruding portion 331c are integrally connected to each other so as to surround the outside of the flat portion 331b. Such a torsion spring 331 can be formed by simultaneously punching and bending a metal plate material with a press.

  The first spacer 332 mainly has a surface (a second surface) of the flat portion 331b on which the protrusion 331c protrudes so that the mirror 301 as the first member can be mounted on the flat portion 331b while avoiding the protrusion 331c. (On one surface) to raise the mounting position of the mirror 301 to the same height as the protrusion 331c. The spacer portion 332b is a spacer having the same height as the protrusion 331c, which raises the height. The spacer portion 332b is connected to the outer peripheral portion 332a by a bridge 332d.

The outer peripheral portion 332a is formed in the same shape as the flat portion 331a of the torsion spring 331, and includes a projection 332c that covers the projection 331c at a position corresponding to the projection 331c. Note that it is not always necessary to secure a space for the outer peripheral portion 332a. However, in the case of simultaneous production of a large number of pieces as described later with reference to FIG. Since it is difficult to form a single sheet, the torsion spring 331 is also provided as a protective material for supporting the bridge 332d.
The material of the first spacer 332 is not particularly limited as long as it can fix both the torsion spring 331 and the mirror 301. There is no need to have elasticity.

  On the other hand, when the torsion spring 331 is made of a material that is not suitable for soldering, such as stainless steel, the second spacer 333 is a surface (second surface) of the flat portion 331b opposite to the side on which the protrusion 331c protrudes. And used as a base for fixing the permanent magnet 321 as the second member to the flat portion 331b by soldering. The spacer portion 333b plays the role of this base. The spacer portion 333b is connected to the outer peripheral portion 333a by a bridge 333d.

The outer peripheral portion 333a is also formed in the same shape as the flat portion 331a of the torsion spring 331, and includes a projection 333c at a position corresponding to the projection 331c to cover the back side of the projection 331c. The reason for providing the outer peripheral portion 333a is the same as in the case of the outer peripheral portion 332a.
The material of the second spacer 333 is a material that can be fixed to the torsion spring 331 and can be soldered. For example, if the torsion spring 331 is stainless steel, phosphor bronze is suitable as the material of the second spacer.

When manufacturing the mover 330, the following steps may be performed.
First, as shown in FIG. 9B, the first spacer 332 on the side of the torsion spring 331 on the protrusion 331c and the second spacer 333 on the side opposite to the protrusion 331c can be kept fixed even in a heating step described later. As described above, it is fixed by bonding or crimping. FIG. 10 shows an example in which an adhesive is used for bonding the first spacer 332 and the second spacer 333, respectively, which are shown as adhesives 341 and 342. However, a heat-resistant adhesive that does not melt in the heating step is used. Alternatively, a molecular compression bonding method may be used.
FIG. 10 is a cross-sectional view taken along a plane passing through the vicinity of the center of the plane portion 332b and perpendicular to the longitudinal direction of the protrusion 332c. Also, the thickness of the adhesive layer is considerably emphasized from the actual thickness so that members used for bonding between components can be described.

Next, bridges 332d and 333d unnecessary for the completed product of the mover 330 are removed by dicing or the like.
Thereafter, an adhesive layer 343 made of a material that is melted by heating is applied to the spacer portion 332b of the first spacer 332, and the mirror 301 is disposed thereon. Since the spacer 331b is at the same height as the protrusion 331c, the mirror 301 can be disposed across the protrusion 331c without the protrusion 331c becoming an obstacle. In FIG. 10, the spacer portion 332b appears to be slightly lower than the protrusion 331c by the amount of the adhesive layer 343, but the adhesive layer 343 is actually thin, and there is substantially no difference between the heights of the two.
It is desirable to use a low-melting glass paste for the adhesive layer 343. When heat treatment is required for bonding, if the glass constituting the mirror 301 and the adhesive have different shrinkage rates, the mirror 301 may be distorted due to shrinkage during cooling and scanning accuracy may be reduced. This is because paste can avoid this.

Also, the adhesive layer 344 made of a material that is melted by heating is applied to the spacer portion 333b of the second spacer 333, and the permanent magnet 321 is disposed thereon (the lower side in FIG. 10). As in the case of the mover 320, the poles 321n are arranged so that the N pole 321n is located on one side and the S pole 321s is located on the other side across the projection 331c. It is desirable to use cream solder as the adhesive layer 344 from the viewpoint of cost, but it is not limited to this. Further, as the permanent magnet 321, it is desirable to use a samarium-cobalt type magnet instead of a neodymium type so as to withstand the subsequent heating step.
The laminate in which the mirror 301 and the permanent magnet 321 are disposed is almost identical in appearance to the mover 330 shown in FIG. 9C.

Finally, by heating this laminate, the adhesive layers 343 and 344 are melted, and the fixing of the mirror 301 and the permanent magnet 321 is completed. Thus, the mover 330 is completed.
The mover 330 can be fixed and used on the top yoke 314 shown in FIGS. 6 and 8A and the like, similarly to the case of the mover 320, and swings the mirror 301 according to the energization of the drive coil 316. Can be moved. In this case, of course, the mover holding portion 314 a of the top yoke 314 has a configuration that matches the structure and shape of the mover 330.

The above-mentioned mover 330 can be manufactured by laminating and bonding substantially planar members, although there are projections, and by cutting them as necessary, which is suitable for mass production.
A plurality of torsion springs 331, first spacers 332, and second spacers 333 can be prepared as sheet-like members in a state of being connected and arranged in a plane, and can be stacked and fixed in that state.

FIG. 11 shows a state where the layers are stacked and fixed.
In FIG. 11, the torsion spring 331, the first spacer 332, and the second spacer 333 are respectively arranged in three rows and four columns on one sheet. FIG. 11 shows a state in which the bridges 332d and 333d have been removed by dicing.
The operation of forming the adhesive layers 343 and 344 on the laminate in this state and arranging the mirror 301 and the permanent magnet 321 corresponding to each of the movable elements 330 is performed by an electronic component using a conventional surface mounting (SMT) technology. It can be done very efficiently by using an automatic component mounting machine.

In addition, if a reflow furnace is used, the heat treatment can be easily performed by using a device that has been widely used in the past.
FIG. 11 shows a state in which the mirror 301 (and the permanent magnet 321 hidden behind) is fixed only to the upper left individual, but the same fixing can be performed to all the individuals at the same time. Thereafter, the mover 330 of each individual can be separated. It should be noted that depending on the use of the mover 330, it is not hindered to use the plurality of movers 330 in a connected state.

By adopting the above configuration, it is possible to efficiently manufacture the mover 330 usable for the actuator 300 in the same process as the mounting of the conventionally used electronic component by using the conventionally used device. it can. Therefore, the mover 330 can be manufactured at low cost, which contributes to the cost reduction of the actuator 300.
When the permanent magnet 321 can be directly soldered to the torsion spring 331, the second spacer 333 can be omitted. In this case, the adhesive layer 344 may be formed directly on the surface of the flat portion 331b opposite to the protrusion 331c, and the permanent magnet 321 may be disposed thereon.

  Also, in the mover 330, similarly to the case of the mover 320, the permanent magnet 321 is provided as a first member on the surface of the flat portion 331b on the side where the protrusion 331c projects, and the mirror 301 is used as a second member. It may be provided on the opposite surface. In this case, the description has been given above except that the permanent magnet 321 is fixed on the first spacer 332 and the mirror 310 is fixed on the second spacer 333, and the material of each spacer and the adhesive layer to be used are changed accordingly. Structures and manufacturing methods are equally applicable.

[4. Control of Beam Lighting Interval According to Scanning Position in Main Scanning Direction (FIGS. 12 to 17)]
Next, the control of the beam lighting interval according to the scanning position of the emitted light L2 in the main scanning direction will be described. Since the scanning position in the main scanning direction corresponds to the direction of the mirror 301 in the actuator 300, the control described here is also control according to the direction of the mirror 301.

First, characteristics of the swing operation of the mirror 301 by the actuator 300 will be described with reference to FIGS.
FIG. 12 is a graph showing the relationship between the scanning angle of the mirror 301 and the absolute value of the scanning angular velocity, FIG. 13 is a diagram showing an example of a drive signal of the LD module 21, and FIG. It is a figure showing an example of a spot by L2.

  Experiments by the inventors have revealed that the moving speed of the mirror 301 oscillated by the actuator 300 is not constant. Since the mirror 301 stops at the end of the swing path and moves in other parts, it is clear that the moving speed fluctuates. However, as shown in FIG. Slower in the middle and faster in the middle. When rotating counterclockwise and clockwise, only the direction of movement is different, and the speed is almost the same at the same position.

Therefore, in FIG. 12, the position on the swing path (expressed by the rotation angle and referred to as “scan angle”) is plotted on the horizontal axis, and the absolute value of the angular velocity at that position is plotted on the vertical axis. 5 illustrates the change.
As described above, since the rotation speed of the mirror 301 fluctuates, when the LD module 21 is driven by the drive signal drv1 having pulses at regular intervals as shown in FIG. The spot 72 of the emitted light L2 is formed. That is, spots are formed which are coarse at the center in the main scanning direction and finely distributed at the ends. For this reason, the detection resolution of the object is also coarser at the center than at the ends.

This situation is not preferable when the detection of an obstacle is considered as a use of the object detection device 10 because the importance near the center of the visual field is considered to be the highest.
Therefore, the object detection device 10 is provided with a control circuit for controlling the pulse interval of the drive signal of the LD module 21 according to the scanning angle of the mirror 301.

FIG. 15 shows the configuration of the control circuit.
The control circuit 351 illustrated in FIG. 15 corresponds to a cycle control unit, and roughly performs operations related to drive control of the drive coil 316, detection of the rotation speed of the mirror 301, and control of the lighting interval of the LD module 21.

  First, regarding the drive control of the drive coil 316, the control circuit 351 sets the range of scan and the value of the period to be executed by the actuator 300 for the drive signal generation circuit 352 that generates the drive signal 353 to be applied to the drive coil 316. I do. The drive signal generation circuit 352 generates a drive signal 353 having an appropriate level and a voltage that fluctuates at an appropriate cycle according to the set value, and applies the generated drive signal 353 to the drive coil 316 of the actuator 300. This allows the actuator 301 to swing the mirror 301 as described with reference to FIG. 8A.

  Next, regarding the detection of the rotation speed of the mirror 301, the detection circuit 354 detects an induced voltage generated in the sensing coil 317 of the actuator 300, and the ADC (analog-digital converter) 355 converts the voltage into a digital value in real time. Are corrected by the difference calculation unit 357 and supplied to the control circuit 351. The control circuit 351 calculates the rotation speed of the mirror 301 based on the voltage value. The number of turns of the sensing coil 317 is the same as that of the drive coil 316, and may be reversely wound with respect to the drive coil 316, but is not limited thereto.

Here, when the mirror 301 is swung, induced electromotive force is generated in the sensing coil 317 due to two types of factors.
The first factor is an induced electromotive force caused by a change in the strength and direction of a magnetic field generated by the drive coil 316 due to a voltage change of a drive signal applied to the drive coil 316.
The second factor is induced electromotive force due to fluctuations in the strength of the magnetic field caused by the swing of the permanent magnet 321. When the permanent magnet 321 oscillates as described with reference to FIG. 8A, it can be considered that the fluctuation speed of the magnetic field intensity generated in the sensing coil 317 is substantially proportional to the rotational angular speed of the permanent magnet 321. Since the rotational angular velocity of the permanent magnet 321 is also the rotational angular velocity of the mirror 301, it can be considered that the intensity of the induced electromotive force generated by the second factor is proportional to the rotational angular velocity of the mirror 301.

The mutual induction voltage pattern storage unit 356 and the difference calculation unit 357 are provided to subtract the value of the induced electromotive force due to the first factor from the output of the ADC 355.
That is, the mutual induction voltage pattern storage unit 356 stores the transition of the voltage value of the induced voltage generated in the sensing coil 317 by the mutual induction when the drive signal is applied to the drive coil 316 with the permanent magnet 321 removed in the actuator 300. , And one cycle of the drive signal is stored in association with the phase of the drive signal. Then, when applying a drive signal to the drive coil 316 to swing the mirror 301, the drive signal generation circuit 352 supplies a timing signal indicating the phase of the drive signal to the mutual induction voltage pattern storage unit 356. The mutual induction voltage pattern storage unit 356 supplies a voltage value corresponding to the current timing to the difference calculation unit 357 based on the timing signal.

The difference calculation unit 357 subtracts the voltage value supplied from the mutual induction voltage pattern storage unit 356 as the mutual induction contribution from the value of the induction voltage actually generated in the sensing coil 317 supplied from the ADC 355. Is supplied to the control circuit 351.
As described above, the value of the induced voltage proportional to the rotation angular velocity of the mirror 301 can be supplied to the control circuit 351. When the change of the induced voltage supplied to the control circuit 351 is plotted with the time corresponding to a half cycle from one end to the other end of the swing range of the mirror 301 on the horizontal axis, as shown in a graph 361, the graph is shown in FIG. It is considered that the shape becomes substantially similar to the graph of the rotational angular velocity.

The control circuit 351 multiplies the voltage value VR (t) supplied from the difference calculation unit 357 at time t by a proportionality constant K obtained in advance and sets the angular velocity ω (t) of the mirror 301 to ω (t ) = K × VR (t).
The value of K is obtained, for example, by comparing a value obtained by measuring the rotation angle of the mirror 301 for a half cycle by other means with an integral value of the voltage value VR (t) for a half cycle.

Further, the control circuit 351 can use ω (t) to determine a lighting interval T for lighting the LD module 21 so that a desired resolution is obtained on the scanning line 71a in the main scanning direction. Assuming that the resolution is ψ degrees, T = π · (ψ / 180) / ω (t).
The control circuit 351 calculates the lighting interval T in real time in response to the supply of the voltage value VR (t) from the difference calculator 357 in order to control the lighting interval of the LD module 21, and a pulse indicating the value of T. The width modulation signal is supplied to the pulse generator 358.

  The pulse generator 358 performs pulse width modulation in accordance with the pulse width modulation signal, generates a timing signal having pulses at intervals T, and supplies the timing signal to the laser drive circuit 22. The laser drive circuit 22 generates a drive signal for turning on the LD module 21 at a pulse timing included in the timing signal supplied from the pulse generator 358, and supplies the drive signal to the LD module 21.

  A graph 362 shows the pulse interval supplied from the control circuit 351 to the pulse generator 358 with respect to the period from one end to the other end of the swing range of the mirror with time taken on the horizontal axis similarly to the graph 361. . That is, according to the induced voltage generated in the sensing coil 317, when the mirror 301 is located near the center of the swing path and the induced voltage is at a high level (first level), the control circuit 351 turns the mirror 301 on. This means that control is performed such that the blinking cycle of the LD module 21 is shorter than when the induced voltage is near the end of the swing path and the induced voltage is at a low level (second level).

As a result, the drive signal of the LD module 21 generated by the laser drive circuit 22 has a different pulse interval according to the moving speed of the mirror 301, as in drv2 shown in FIG. Then, the beam spot 72 obtained by deflecting the laser beam L1 controlled to be lit by the mirror 301 on the scanning line 71a in the main scanning direction over the entire length thereof as shown in FIG. They will be arranged at equal intervals. Thus, the object detection device 10 can detect the object with substantially uniform resolution in the field of view 70.
In the sub-scanning direction, since the mirror 351 is stationary while scanning for one line in the main scanning direction, the above-described problem does not occur, and it is not necessary to adjust the lighting interval.

Note that the above-described control circuit 351 may be provided as a part of the processor 53 or may be provided separately from the processor 53. Further, the function of the control circuit 351 may be realized by dedicated hardware, realized by causing a general-purpose processor to execute software, or a combination thereof.
In the example of FIG. 15, an example in which the control is performed based on the voltage value of the induced voltage generated in the sensing coil 317 has been described. However, the same control can be performed by using the current value of the induced current.

[5. Configuration of light receiving section 40 (FIGS. 18 to 24)]
Next, the configuration of the light receiving unit 40 will be described in detail. The object detection device 10 has one feature in the light receiving unit 40 at the point where the aperture 44 is provided on the focal plane of the condenser lens 42. Therefore, the description will be focused on this point.

First, the properties of the laser beam L1 emitted from the light emitting unit 20 will be described.
FIG. 18 is a diagram schematically illustrating an optical path of a laser beam emitted from the light emitting unit 20.
The LD module 21 of the light projecting unit 20 has a plurality of light emitting points 21a1 to 21a3 as shown in FIG. The light emitting points 21a1 to 21a3 respectively output laser beams B1 to B3 having a certain extent. Further, these light emitting points 21a1 to 21a3 are arranged at close positions, but are necessarily arranged with a certain extent. Of course, the number is not limited to three.

  On the other hand, the light projecting optical system 23 is designed to generate a parallel light beam from the laser light output from the LD module 21. For example, if the light projecting optical system 23 is configured by a convex lens in which one of the light emitting points (here, the light emitting point 21a2) is located at the focal point, the laser light B2 output from the light emitting point is output by the power of the convex lens. Accordingly, it is possible to form a parallel light beam C2 that travels along the optical axis of the convex lens.

However, the laser beams B1 and B3 output from the light-emitting points 21a1 and 21a3 that are on the focal plane but deviated from the focal point become parallel light due to the power of the convex lens, but are slightly inclined with respect to the optical axis. The beams C1 and C3 travel in the directions.
Therefore, as a whole, the laser beams output from the light emitting points 21a1 to 21a3 become laser beams that are substantially parallel but slightly spread when passing through the light projecting optical system 23. The angle of this spread can be regarded as constant at a position sufficiently distant from the light projecting optical system 23, and the angle is defined as the divergence angle α of the laser beam L1 or the emitted light L2.

Next, a detailed configuration and effects of the aperture 44 provided in the light receiving unit 40 will be described.
First, in the object detection device 10 of this embodiment, a silicon photomultiplier (SiPM) is used as the light receiving element 43 provided in the light receiving unit 40. The SiPM is an array of avalanche photodiodes (APDs) operating in the Geiger mode, and provides high detection sensitivity that can be detected from one photon, high multiplication factor, high-speed response, excellent time resolution, and the like.

  As an example, in a general APD, when an output signal has an amplification factor of about 50 times an input signal (intensity of light incident on a light receiving surface), an MPPC (Multi-pixel Photon Counter: (Registered trademark), it is possible to obtain an amplification factor of about 100,000 times (https://www.hamamatsu.com/resources/pdf/ssd/Photodetector_lidar_kapd0005e.pdf).

  Therefore, since the weak return light L4 can be detected by using the SiPM, it is possible to configure an object detection device capable of detecting a distant object having a low light reflectance using a low-intensity laser beam. it can. Since the SiPM can obtain an amplification factor of about 2000 times that of the APD, theoretically, the use of the SiPM uses a laser beam having a power of 1/2000 and the same level as that of the object detection apparatus using the APD. Object detection capability can be obtained.

  In order to increase the intensity of the laser beam, a large and expensive device is required. Therefore, the fact that the intensity of the laser beam may be low has a great advantage in reducing the size and cost of the object detection device. However, the size of the light receiving surface of the SiPM is larger than that of the APD. Therefore, if the APD is simply replaced with the SiPM, there is a problem that the APD is easily affected by disturbance light.

This will be described with reference to FIG. FIG. 19 is a diagram illustrating an optical path of the return light L4 condensed by the condenser lens 42 when the aperture 44 is not provided.
In the light receiving unit 40, the condenser lens 42 is designed to form an image of the incident return light L4 on the focal plane. Here, the focal length is f. The return light corresponds to the fact that the emitted light has the divergence angle α as described with reference to FIG. 18, and returns to the object detection device 10 from the visual field range having the spread of α. However, here, the return light L4 is once considered to be completely parallel light.

  Then, the return light L4 incident on the condenser lens 42 along the optical axis is collected at the focal point of the condenser lens 42, and then diverges. In order to receive the return light L4 over the entire light receiving surface of the light receiving element 43, it is preferable to arrange the light receiving element 43 at a position beyond the focal point where the return light L4 spreads over the width D 'of the light receiving surface. At this time, the distance from the condenser lens 42 to the light receiving element 43 is d '. The light receiving element 43 may be arranged before the focal point. In this case, d 'can be reduced to reduce the size of the device. However, from the viewpoint of reducing the influence of disturbance light, the light receiving element 43 should be arranged before the focal point. Is preferred.

  Incidentally, not only the return light L4 but also disturbance light from various directions is incident on the object detection device 10. Part of the light reaches the light receiving unit 40 along the same or close optical path as the return light L4. In consideration of the property that light passing through the center of the condenser lens 42 travels straight even after passing through the condenser lens 42, the disturbance light X in the range of the viewing angle φ indicated by a broken line in FIG. The disturbance light incident on the condenser lens 42 is incident on the light receiving element 43. The value of φ can be approximately determined by φ = arctan (D ′ / d ′). “Arctan” is the arc tangent.

When an APD is used as the light receiving element 43, the effective diameter of the light receiving surface is, for example, about 0.08 mm. Therefore, if D ′ = 50 mm, φ ≒ 0.1 degrees, and only a very limited range of disturbance light is received by the light receiving element. It does not enter 43. Therefore, the influence of the disturbance light X on the object detection is limited.
However, when SiPM is used as the light receiving element 43, the effective diameter of the light receiving surface is, for example, about 1.3 mm. Then, when D ′ = 50 mm, φ ≒ 1.5 degrees, and disturbance light having a considerably wide viewing angle is obtained. Is incident on the light receiving element 43. The sensitivity of the SiPM may be extremely high. In this situation, when the sunlight is strong, the light receiving element 43 is saturated by the disturbance light X, the return light L4 cannot be detected, and the distance measurement cannot be performed.

Therefore, the configuration of FIG. 19 has a problem that it is difficult to use SiPM as the light receiving element of the object detection device.
Thus, in this embodiment, this problem has been solved by providing the aperture 44 on the focal plane of the condenser lens 42.

This point will be described with reference to FIGS. FIG. 20 is a diagram illustrating an optical path of the return light L4 condensed by the condenser lens 42 when the aperture 44 is present. FIG. 21 is a diagram showing the arrangement of the light transmitting areas of the aperture 44. As shown in FIG.
The aperture 44 is provided on the focal plane of the condenser lens 42, has a light transmitting area (opening) 44a for passing the return light L4, and the other part is a light shielding area 44b.

  Here, since the return light L4 actually returns from the visual field range of the spread angle α, even if the aberration of the condenser lens 42 is not taken into account, the return light L4 does not form an image at one point of the focus, and is approximated. Is formed on the focal plane as a spot having a diameter of f · tan α. Therefore, in order to allow all of the return light L4 to pass, the diameter D of the light transmitting area 44a also needs to be at least f · tanα. However, considering the assembly error of the parts, it is better that the diameter D is slightly larger than the minimum value.

On the other hand, if the distance from the condenser lens 42 to the aperture 44 is d (equal to the focal length f of the condenser lens 42 in the example of FIG. 20), the disturbance light X passing through the light transmission area 44a of the aperture 44 The angle is in the range of β = arctan (D / d). Therefore, even if D is too large, the influence of disturbance light increases.
According to the simulations of the present inventors in consideration of the above, if the diameter D of the light transmitting area 44a is determined within the range of 1 ≦ β / α ≦ 3, it is possible to allow some assembling error while suppressing the influence of disturbance light. Thus, the object detection device 10 with high yield and high reliability can be configured.

  By providing the aperture 44 as described above, disturbance light from outside the range of the viewing angle β as shown by a broken line in FIG. 22 is shielded by the aperture 44 so as not to enter the light receiving element 43. it can. As compared with the configuration shown in FIG. 19, as shown in FIG. 23, disturbance light X incident from a range between the viewing angle φ and the viewing angle β around the optical axis of the condenser lens 42 is It can also be understood that light can be shielded. On the other hand, since the return light L4 that enters from the range of the viewing angle (divergence angle) α passes through the aperture 44 and enters the light receiving element 43, it can be detected. Of course, the aperture 44 may shield disturbance light outside the viewing angle φ.

  In addition, the arrangement of the apertures 44 does not have a significant effect in terms of cost and manufacturing difficulty. Accordingly, it can be said that the aperture 44 can easily and inexpensively reduce the influence of disturbance light. As a result, it is possible to configure the low-cost object detection device with high detection sensitivity by utilizing the characteristics of SiPM. However, it is not essential to use SiPM, and the present invention is naturally applicable to reduce the influence of disturbance light on other light receiving elements.

  Although the aperture 44 is provided on the focal plane of the condenser lens 42 in the example of FIG. 20, this is not essential. Since the spot of the return light L4 is the smallest on the focal plane, providing the aperture 44 on the focal plane can reduce the diameter of the light transmitting area 44a, which is most effective for blocking disturbance light. Even if it is provided at a position deviated from the position, a certain effect can be obtained if the light transmitting area 44a is sized to fit the spot of the return light L4 at that position. If the deviation from the focal plane does not substantially affect the diameter of the light transmitting area 44a, it can be regarded as the same as that provided on the focal plane.

  Although not shown in FIG. 20, in the light receiving unit 40, the mirror 41 for guiding the return light L4 to the condenser lens 42 has a through hole 41a for passing the emitted laser beam L1. For this reason, the return light L4 is not reflected at the portion of the through hole 41a, so that the spot of the return light L4 incident on the light receiving element 43 becomes a dark spot in the area corresponding to the through hole 41a. Then, it becomes difficult to obtain a peak detection signal in a dark portion, so that the substantial detection sensitivity of the light receiving element 43 is reduced accordingly.

  Therefore, as shown in FIG. 24, a light diffusing member 46 may be provided between the aperture 44 and the light receiving element 43 to diffuse the return light L4 and make it incident on the light receiving element 43. By doing so, the return light L4 can be made to be substantially uniformly incident on the entire light receiving surface of the light receiving element 43, and a decrease in detection sensitivity can be prevented. As the light diffusing member 46, it is conceivable to use ground glass or a holographic diffuser.

[6. Other modified examples]
Although the description of the embodiment has been completed above, in the present invention, the specific configuration of the object detection device, the specific operation procedure, the size of each part, the value of other parameters, the specific shape of parts, etc. The invention is not limited to those described in the embodiments.
For example, the condenser lens 42 and the light projecting optical system 23 in the above-described embodiment can be configured not only by a single lens but also by combining the powers of a plurality of lenses.

The features described in each of the above items can be independently applied to an apparatus or a system. In particular, the light receiving section 40, the actuator 300, the movers 320 and 330, and the like can be distributed independently as components. Further, the application is not limited to the object detection device.
In addition, the above-described object detection device 10 can be configured in a size that can be placed on the palm of a human hand, and is suitable for being mounted on an automobile and used as an obstacle detection device for automatic driving. The purpose of use is not limited to this. It can be fixed to a pillar or wall, and used for fixed point observation.

  Further, according to an embodiment of the program of the present invention, one computer or a plurality of computers cooperate to control required hardware, and the light emission of the LD module 21 in the object detection device 10 in the above-described embodiment. This is a program for realizing a function including a timing adjustment function or executing the processing described in the above-described embodiment.

  Such a program may be stored in a ROM or other non-volatile storage medium (flash memory, EEPROM, or the like) included in the computer from the beginning. It can also be provided by recording it on an arbitrary non-volatile recording medium such as a memory card, a CD, a DVD, and a Blu-ray disc. Further, it is also possible to download the program from an external device connected to a network, install the program on a computer, and execute the program.

  Also, the configurations of the above-described embodiments and modified examples can be implemented in any combination as long as they do not contradict each other, and it goes without saying that only a part can be taken out and implemented.

DESCRIPTION OF SYMBOLS 10 ... Object detection apparatus, 20 ... Light emitting part, 21 ... LD module, 22 ... Laser drive circuit, 23 ... Light emitting optical system, 30 ... Scanning part, 31 ... Mirror, 32 ... Actuator, 40 ... Light receiving part, 41, 48 mirror, 42 condenser lens, 43 light receiving element, 44 aperture, 46 light diffusion member, 51 front end circuit, 52 TDC, 53 processor, 54 input / output unit, 61 top cover, 62: rear cover, 63: cover clip, 64: protective material, 70: visual field, 71: scanning line, 72: spot, 300, 380: actuator, 301, 381: mirror, 304, 384: rotation axis, 311: core yoke, 312: Frame yoke, 313: Coil assembly, 314: Top yoke, 315: Screw, 316: Drive coil, 317: Sensing coil , 302, 330 ... mover, 321 ... permanent magnet, 321s ... S pole, 321n ... N pole, 322, 331 ... torsion spring, 323 ... connection holder, 332 ... first spacer, 333 ... second spacer, 341-344 ... adhesive layer, 351 ... control circuit, 352 ... drive signal generation circuit, 353 ... drive signal, 354 ... detection circuit, 355 ... ADC, 356 ... mutual induction voltage pattern storage section, 357 ... difference calculation section, 358 ... pulse generator , 382: axis, 383: holder, L1: laser beam, L2: outgoing light, L3, L4: return light

The present invention relates to an object detection device that uses a laser beam to detect an object on the optical path of the laser beam .

The present invention has been made in view of such circumstances, and it is an object of the present invention to realize a scanning that periodically changes a projection direction of a laser beam with a small and highly durable configuration .

The object detection device includes a light projecting unit that projects a laser beam to the outside, a scanning unit that periodically changes the direction in which the laser beam is projected by the light projecting unit, a light receiving element, and a light receiving element. Based on the light receiving optical system leading to the light receiving element, the light emitting timing and the light emitting direction of the laser beam, and the timing of the light detection signal output by the light receiving element, the distance to the object on the optical path of the laser beam and An object detection device comprising: an object detection unit that detects a direction in which the object is located; wherein the scanning unit is a torsion spring fixed to a support member, and the laser beam is fixed to one surface of the torsion spring. a mirror for reflecting, fixed to the other side of the torsion spring, said torsion N pole on one side straddling the rotation axis of the spring, a permanent magnet located the S pole on the other side, above the permanent magnet Torsion Comprising a arranged driving coils on the opposite side of the I, and the magnetic body surrounding the driving coil, and a driver for applying a drive signal periodically voltage or current to the drive coil changes, the mirror, the It reciprocates in response to the application of the drive signal.
In such an object detecting device, ends of the magnetic body facing the N pole and S pole of the permanent magnet are respectively directed from one end of the drive coil axis facing the permanent magnet along the axis. In view of the above, it is preferable that the magnet is located at a position separated from the center line of the permanent magnet connecting the N pole and the S pole.
Further , protrusions extending from both sides of the mover toward the mover including the torsion spring, the mirror, and the permanent magnet such that the magnetic body faces the N pole and the S pole of the permanent magnet. Wherein each of the projections has an end facing the N-pole and the S-pole of the permanent magnet, respectively, as viewed in a direction along the axis from one end of the drive coil shaft facing the permanent magnet. It is preferable that the permanent magnet is located at a position distant from the center line of the permanent magnet connecting the N pole and the S pole.

Further, in any of the above object detection devices, the torsion spring is a torsion spring formed of a plate material having a fold, and the torsion spring includes a linear projection formed by the fold, and the permanent magnet Preferably, the torsion spring is fixed to the other surface so as to straddle the protrusion, and the N pole is located on one side and the S pole is located on the other side straddling the protrusion.
Furthermore, it is preferable that the cross-sectional shape of the protrusion is V-shaped.
Further, it is preferable that one end of the shaft of the drive coil faces an intermediate point between the S pole and the N pole of the permanent magnet.

According to the configuration of the present invention as described above, it is possible to realize the scanning in which the projection direction of the laser beam is periodically changed with a small and highly durable configuration .

[5. Configuration of light receiving section 40 (FIGS. 18 to 24)]
Next, the configuration of the light receiving unit 40 will be described in detail. The object detection device 10 has one feature in the light receiving unit 40 at the point where the aperture 44 is provided on the focal plane of the condenser lens 42. Therefore, the description will be focused on this point.
By the way, in the detection of an object by a rider, in order to detect an object having a lower light reflectance at a longer distance, the detection sensitivity of a light receiving element (light detection element) is increased so that weaker reflected light can be detected. An approach is conceivable. However, from the optical path for taking in the reflected light from the object, disturbance light also enters, so if the detection sensitivity of the light receiving element is increased, not only the reflected light from the object but also the detection signal of the disturbance light increases, There is a high possibility that the disturbance light is erroneously recognized as the reflected light from the object.
Therefore, conventionally, there have been many approaches to increase the output of a laser beam to be irradiated to increase the intensity of reflected light and relatively reduce the influence of disturbance light. However, in this approach, the apparatus becomes large and expensive to generate a high-power laser beam, and projecting a high-power laser beam on a road has safety problems.
The above-described problem of disturbance light similarly occurs when an object in only one direction is detected without assuming scanning by a laser beam.
The configuration described in this section has been made in view of such circumstances, and when detecting reflected light incident from the outside of a laser beam emitted to the outside using a light receiving element, disturbance is easily and inexpensively performed. It aims at reducing the influence of light.

The object detection device includes a light projecting unit that projects a laser beam to the outside, a scanning unit that periodically changes the direction in which the laser beam is projected by the light projecting unit, a light receiving element, and a light receiving element. Based on the light receiving optical system leading to the light receiving element, the light emitting timing and the light emitting direction of the laser beam, and the timing of the light detection signal output by the light receiving element, the distance to the object on the optical path of the laser beam and An object detection device comprising: an object detection unit that detects a direction in which the object is located; wherein the scanning unit is a torsion spring fixed to a support member, and the laser beam is fixed to one surface of the torsion spring. A permanent magnet fixed to the other surface of the torsion spring and having an N pole on one side and an S pole on the other side across the rotation axis of the torsion spring; Torsion A driving coil disposed on the side opposite to the spring, a magnetic body surrounding the driving coil, and a driving unit that applies a driving signal in which a voltage or current periodically changes to the driving coil; It reciprocates in response to the application of the drive signal.
In such an object detecting device, ends of the magnetic body facing the N pole and S pole of the permanent magnet are respectively directed from one end of the drive coil axis facing the permanent magnet along the axis. In view of the above, it is preferable that the magnet is located at a position separated from the center line of the permanent magnet connecting the N pole and the S pole. Further, the torsion spring is a torsion spring formed of a plate material having a fold, and the torsion spring includes a linear protrusion formed by the fold, and the permanent magnet is formed so as to straddle the protrusion. It is preferable that the N pole is fixed to the other surface of the torsion spring and the N pole is located on one side and the S pole is located on the other side across the projection.
Further, protrusions extending from both sides of the mover toward the mover including the torsion spring, the mirror, and the permanent magnet such that the magnetic body faces the N pole and the S pole of the permanent magnet. Wherein each of the projections has an end facing the N-pole and the S-pole of the permanent magnet, respectively, as viewed in a direction along the axis from one end of the drive coil shaft facing the permanent magnet. It is preferable that the permanent magnet is located at a position distant from the center line of the permanent magnet connecting the N pole and the S pole.

Further, Oite to any of the object detection apparatus described above, may the cross-sectional shape of the protruding portions is a V-shape.
Further, it is preferable that one end of the shaft of the drive coil faces an intermediate point between the S pole and the N pole of the permanent magnet.

Claims (22)

A light-emitting unit that emits a laser beam to the outside,
A light receiving element,
A light receiving optical system for guiding incident light from the outside to the light receiving element,
An object detection device, comprising: an object detection unit that detects a distance to an object on an optical path of the laser beam based on a timing of projecting the laser beam and a timing of a light detection signal output by the light receiving element. ,
The light receiving optical system,
A condenser lens that forms an image of incident light on a predetermined focal plane,
An aperture disposed on a focal plane of the condenser lens. The object detection device according to claim 1,
The divergence angle at the time of projecting the laser beam by the light projecting unit is α, the diameter of the light transmitting area of the aperture is D, the distance from the condenser lens to the aperture is d, and β = arctan (D / d). , Α ≦ β. The object detection device according to claim 2,
An object detection device, wherein 1 ≦ β / α ≦ 3. The object detection device according to any one of claims 1 to 3,
The light receiving element is a silicon photomultiplier (SiPM),
An object detection device, wherein the light passing through the condenser lens is incident on the entire light receiving surface of the silicon photomultiplier. The object detection device according to any one of claims 1 to 4,
An object detection device, comprising: a light diffusion member between the aperture and the light receiving element. The object detection device according to any one of claims 1 to 5,
A scanning unit for periodically changing a light emitting direction of the laser beam by the light emitting unit,
The object detection unit is configured to determine a distance to an object on an optical path of the laser beam and the object based on a timing and an emission direction of the laser beam and a timing of a light detection signal output from the light receiving element. An object detection device for detecting a direction. Emits a laser beam to the outside,
Focus the incoming light from the outside on a predetermined focal plane by a condenser lens,
By an aperture arranged on a focal plane of the condenser lens, the light collected by the condenser lens is stopped down,
Light passing through the aperture is incident on a light receiving element,
An object detection method, comprising: detecting a distance to an object on an optical path of the laser beam based on timing of projecting the laser beam and timing of a light detection signal output by the light receiving element. A light-emitting unit that emits a laser beam to the outside,
A scanning unit for periodically changing a light emitting direction of the laser beam by the light emitting unit,
A light receiving element,
A light receiving optical system for guiding incident light from the outside to the light receiving element,
Object detection for detecting the distance to the object on the optical path of the laser beam and the direction in which the object is located, based on the timing and direction of projection of the laser beam and the timing of a light detection signal output by the light receiving element. And an object detection device comprising:
The scanning unit includes:
A torsion spring formed of a plate material having a fold, comprising a linear projection formed by the fold, a torsion spring fixed to a support member,
A mirror fixed to one surface of the torsion spring and reflecting the laser beam;
A permanent magnet that is fixed to the other surface of the torsion spring so as to straddle the protrusion, and has an N pole on one side and an S pole on the other side straddling the protrusion;
A drive coil disposed on the opposite side of the permanent magnet from the torsion spring;
A sensing coil having a common core with the drive coil;
A magnetic body surrounding the drive coil;
A drive unit that periodically applies a drive signal whose voltage or current changes to the drive coil,
An object detection device, wherein the mirror reciprocates in response to the application of the drive signal. An object detection device according to claim 8,
An object detection device, characterized in that the projection has a V-shaped cross section. The object detection device according to claim 8, wherein:
An object detection device, wherein one end of a shaft of the drive coil faces an intermediate point between an S pole and an N pole of the permanent magnet. The object detection device according to any one of claims 8 to 10, wherein
The end of the magnetic body facing the N pole and the S pole of the permanent magnet is viewed from the one end of the axis of the drive coil facing the permanent magnet in the direction along the axis, and the N pole and the N pole are opposite to each other. An object detection device, wherein the object detection device is located at a position apart from a center line of the permanent magnet connecting to the S pole. The object detection device according to any one of claims 8 to 11,
A detecting unit that detects a voltage or a current generated in the sensing coil; and a cycle control unit that controls a blinking cycle of the laser beam emitted by the light emitting unit according to a level of the voltage or the current detected by the detecting unit. An object detection device comprising: The object detection device according to claim 12,
When the level of the voltage or current detected by the detection unit is a first level indicating that the mirror is near the center of the path of the reciprocal drive, the cycle control unit may control the mirror to perform the reciprocal drive. An object detection device according to claim 1, wherein said blinking cycle is shorter than at a second level indicating that the path is near the end of the path.   A control method for controlling the object detection device according to any one of claims 8 to 10, wherein a voltage or a current generated in the sensing coil is detected, and the level of the detected voltage or current is determined. A control method, comprising: controlling a blink cycle of a laser beam emitted by the light emitting unit. The control method according to claim 14, wherein
When the level of the voltage or the current is the first level indicating that the mirror is near the center of the path of the reciprocating drive according to the level of the voltage or the current generated in the sensing coil, A control method characterized by controlling a blinking cycle of the laser beam so as to shorten a blinking cycle as compared to a case where the second level indicates that the path is near an end of the reciprocating drive path.   A program for causing a processor to control hardware to execute the control method according to claim 14 or 15. A torsion spring formed of a plate material having a fold, wherein the linear protrusion formed by the fold is formed integrally with the protrusion so as to straddle the protrusion near the center of the protrusion. A torsion spring having a flat surface portion,
A first spacer having the same height as the protrusion, fixed to the first surface of the flat portion on the side where the protrusion protrudes;
A first member fixed to a side of the first spacer opposite to the plane portion;
A second member fixed to a second surface of the flat portion opposite to the first surface;
One of the first member and the second member is a mirror, and the other is a magnet. The magnet is fixed so as to straddle the protruding portion. The mover, characterized in that the S pole is located in the movable element. The mover according to claim 17, wherein
A mover having a second spacer between the flat portion and the second member, wherein the second member is fixed to the flat portion via the second spacer. A torsion spring formed of a plate material having a fold, wherein the linear protrusion formed by the fold is formed integrally with the protrusion so as to straddle the protrusion near the center of the protrusion. A first spacer having the same height as the protrusions is bonded or crimped to the first surface of the flat surface on the side where the protrusions protrude, in the torsion spring including A first step of fixing so that the fixing can be maintained even during the heat treatment;
After the first step, a first member is laminated on the first spacer via an adhesive layer that is melted by heating, and a second member is provided on a second surface of the flat portion opposite to the first surface. Is a second step of forming a laminated body via an adhesive layer that is melted by heating, wherein one of the first member and the second member is a mirror, the other is a magnet, and the magnet is: A second step of straddling the protruding portion and laminating such that an N pole is located on one side and an S pole is located on the other side straddling the protruding portion;
And a third step of performing a heat treatment on the laminate formed in the second step, fixing the first member to the first spacer, and fixing the second member to the plane portion. The method of manufacturing the mover. It is a manufacturing method of the mover according to claim 19,
The first step includes a step of fixing the second spacer to the second surface of the plane portion by adhesion or pressure bonding so that the second spacer can be kept fixed even during the heat treatment in the third step.
In the second step, the second member is laminated on a surface of the second spacer opposite to the plane portion via an adhesive layer that is melted by the heating,
In the third step, the method for manufacturing a mover, wherein the second member is fixed to the plane portion via the second spacer. It is a manufacturing method of the mover according to claim 19,
A plurality of the torsion springs and the first spacer are prepared in a state of being connected to each other and arranged in a plane,
In the first step, the plurality of torsion springs and the plurality of first spacers are collectively fixed in a connected state,
In the second step, the laminate is formed for each of the plurality of torsion springs,
The method of manufacturing a mover according to claim 3, wherein, in the third step, the plurality of stacked bodies are collectively subjected to the heat treatment to form a plurality of connected movers. It is a manufacturing method of the mover of Claim 20, Comprising:
A plurality of the torsion springs, the first spacer, and the second spacer are prepared in a state of being connected to each other and arranged in a plane,
In the first step, the plurality of torsion springs, the plurality of first spacers, and the plurality of second spacers are collectively fixed in a connected state,
In the second step, the laminate is formed for each of the plurality of torsion springs,
The method of manufacturing a mover according to claim 3, wherein, in the third step, the plurality of stacked bodies are collectively subjected to the heat treatment to form a plurality of connected movers.

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