JP2019219524A - Light projecting/receiving unit and optical scanner - Google Patents

Abstract

To provide a light projecting/receiving unit which can fix a polygon mirror to a motor shaft in a stable state without rattling, and to provide an optical scanner.SOLUTION: An optical scanner 10 includes a pressing part 80 for fixing a polygon mirror 53 to a motor shaft part 59. The pressing part 80 includes a nut 81, a spring 83 and a pressing member 84. The nut 81 is engaged with a motor shaft 59b of the motor shaft part, and is moved to a predetermined position on the motor shaft by being rotated. In the spring, a position of a rotary shaft 530 of an upper end part 83a is fixed by the nut, in a state where a lower end part 83b is in contact with the pressing member, and the spring presses the polygon mirror part with pressing force according to a predetermined position via the pressing member. The position where the pressing member comes into contact with the polygon mirror part is closer to the rotary shaft than the position where a foundation member 59a of the motor shaft part comes into contact with the polygon mirror part, and a position where the upper end part of the spring comes into contact with the pressing member is closer to the rotary shaft than a position where the pressing member comes into contact with the polygon mirror part.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light emitting and receiving unit and an optical scanning device.

  2. Related Art An optical scanning device that emits laser light toward a measurement space, detects an object based on reflected light from the object, and measures a distance to the object is known.

  More specifically, a laser beam is radiated to a polygon mirror rotated and driven by a motor, the measurement space is scanned by the reflected light, and the reflected light from the object is received by a light receiving means such as a photodiode. Detect objects. Further, the distance from the emission of the laser light to the reception of the reflected light from the object is measured to measure the distance to the object.

  In such an optical scanning device, the polygon mirror is usually fixed to the motor shaft by a screw as a fixing portion and a flat washer (for example, see Patent Document 1 below).

JP-A-2017-138298

  If the polygon mirror is fixed to the motor shaft only by screws and flat washers, the screws and flat washers during the operation of the device, and rattle during rotation if the contact between the flat washers and the polygon mirror is not stable. May occur. Further, at the stage of assembling the device, when fixing the polygon mirror to the motor shaft, the screw cannot be tightened unless the motor shaft is directly pressed or pressed via the polygon mirror. However, if the polygon mirror has a structure that covers the motor shaft, the only option is to directly press the polygon mirror, but if the polygon mirror is formed of resin, etc., extra external force will be applied when the polygon mirror is pressed. May be added and deformed.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light emitting and receiving unit and an optical scanning device capable of stably fixing a polygon mirror to a motor shaft without rattling.

  Another object of the present invention is to provide a light emitting / receiving unit and an optical scanning device capable of preventing an extra external force from being applied to the polygon mirror when the polygon mirror is fixed to the motor shaft by the fixing portion, thereby preventing the polygon mirror from being deformed. is there.

  The above object of the present invention is achieved by the following means.

  (1) A measurement including an emission part for emitting laser light, and a plurality of mirror surfaces, is configured to be rotatable around a rotation axis, and the laser light is reflected by the mirror surface to include an object. A polygon mirror section that scans the space, a light receiving section that receives reflected light reflected from the object, a base member attached to a motor and in contact with the polygon mirror section, and a base member that extends along the rotation axis from the base member. A motor shaft that is formed so as to protrude and penetrates the polygon mirror portion, and a motor shaft portion that transmits the rotation of the motor to the polygon mirror portion, and is in contact with the polygon mirror portion, and the polygon mirror portion is A pressing portion for fixing the polygon mirror portion to the base member by pressing the base member along the rotation axis, and the pressing portion includes: A fixing portion, an elastic member, and a pressing member, wherein the fixing portion is engaged with the motor shaft, and is moved to a predetermined position on the motor shaft by being rotated, and the elastic member is A position in the rotation axis direction of the other end portion is fixed by the fixing portion in a state where one end portion is in contact with the pressing member, and a pressing force corresponding to the predetermined position on the polygon mirror portion via the pressing member. The position where the pressing member contacts the polygon mirror portion is closer to the rotation axis than the position where the base member contacts the polygon mirror portion, and the position where one end of the elastic member contacts the pressing member is A light emitting and receiving unit closer to the rotation axis than a position where the pressing member contacts the polygon mirror unit.

  (2) When the worker presses the polygon mirror portion to the base member by rotating the fixing portion by the operator, the pressing member presses the holding member to fix the fixing portion. (1) The light emitting and receiving unit according to (1), further including a flat portion used to prevent rotation due to rotation.

  (3) The light emitting and receiving unit according to (2), wherein the flat portion of the pressing member is formed at a position farther from the rotation axis than a position at which the pressing member contacts the polygon mirror unit.

  (4) The light emitting and receiving unit according to any one of (1) to (3), wherein the polygon mirror unit has at least three protrusions that are equal in distance from the rotation axis and are in contact with the base member. .

  (5) The light emitting and receiving unit according to any one of (1) to (4), wherein the pressing member has an annular protrusion centered on the rotation axis and in contact with the polygon mirror.

  (6) The light emitting / receiving unit according to any one of (1) to (5), wherein the base of the polygon mirror unit is formed of a resin.

  (7) An optical scanning device, comprising: the light emitting and receiving unit according to any one of (1) to (6); and a control unit that controls the light emitting and receiving unit.

  According to the present invention, the polygon mirror can be fixed to the motor shaft in a stable state without rattling. Further, when the polygon mirror is fixed to the motor shaft portion by the fixing portion, it is possible to prevent the polygon mirror from being deformed due to an unnecessary external force being applied.

FIG. 1 is a schematic sectional view showing an optical scanning device according to one embodiment. FIG. 2 is a schematic block diagram illustrating a configuration of a control unit illustrated in FIG. 1. FIG. 2 is a schematic sectional view of a polygon mirror and a motor shown in FIG. 1. It is sectional drawing to which the A section of FIG. 3 was expanded. FIG. 5 is a perspective view of the polygon mirror shown in FIG. 4 when viewed from a bottom surface direction (Z direction). It is the perspective view which looked at the holding member shown in FIG. 4 from the bottom surface direction (Z direction). It is a figure which shows the modification of the holding member shown in FIG. It is a figure which shows the other modification of the holding member shown in FIG. It is sectional drawing which illustrates about the case where a screw is used as a fixing | fixed part.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference symbols, without redundant description. In addition, the dimensional ratios in the drawings are exaggerated for convenience of description, and may be different from the actual ratios.

  The optical scanning device of the present embodiment reflects a laser beam on a polygon mirror to scan a measurement space two-dimensionally, and reflects reflected light from an object (object) or the like again on the polygon mirror to generate a photodiode. Lead to. Thereby, information on a plurality of directions facing the measurement space can be obtained. The obtained information is called a distance image. The distance image has information on the direction of the object viewed from the laser beam transmitting / receiving unit and the distance to the object.

  FIG. 1 is a schematic sectional view showing an optical scanning device according to the present embodiment. The optical scanning device 10 includes a light emitting / receiving unit 11 and a control unit 12, and is housed in a housing 57.

  The light emitting and receiving unit 11 includes a semiconductor laser 51, a collimating lens 52, a polygon mirror (polygon mirror unit) 53, a lens 54, a photodiode 55, and a motor 56.

  The motor 56 is provided with a motor encoder 61 for detecting a rotation angle of the motor 56. The polygon mirror 53 is provided with a polygon mirror rotation angle detection unit 71 that detects the rotation angle of the polygon mirror 53.

  The control unit 12 controls the light emitting and receiving unit 11. More specifically, it controls the rotation of the motor 56 constituting the light emitting and receiving unit 11 and the emission timing of the laser light of the semiconductor laser 51. Further, the control unit 12 obtains distance information (distance value) according to a time difference from emission of the semiconductor laser 51 to reception of light reflected by the photodiode 55 from an object in the measurement space. From the obtained distance information, a distance image including a plurality of pixels indicating a distribution of distance values to the object in the measurement space is generated. The distance image is also referred to as distance measurement point group data or a distance map.

  FIG. 2 is a schematic block diagram illustrating the configuration of the control unit 12. The control unit 12 is a computer, and includes a CPU 121 as an arithmetic device, a RAM 122 used for a work area and temporary storage, a ROM 123 storing a basic program, and an HDD provided as necessary and storing programs and parameter data. (Hard disk drive) 124 and an I / F unit 125 functioning as an interface for connecting an external device. When the program is executed by the CPU 121, various controls are performed. Such a configuration of the control unit 12 is the same as that of a known computer, and thus a detailed description is omitted. The control unit 12 is connected to the light emitting / receiving unit 11 via an I / F unit 125.

  The control unit 12 controls the rotation speed of the motor 56 based on signals from the motor encoder 61 and the polygon mirror rotation angle detection unit 71. Further, the control unit 12 adjusts the light emission timing of the laser light emitted from the semiconductor laser 51 according to the rotation phase difference between the motor 56 and the polygon mirror 53, which is obtained from the signals from the motor encoder 61 and the polygon mirror rotation angle detection unit 71. Controlling.

  Returning to FIG. The semiconductor laser 51 is a laser light source and emits pulsed laser light. The collimator lens 52 converts divergent light from the semiconductor laser 51 into parallel light. The polygon mirror 53 is configured to be rotatable about a rotation axis 530, and scans and projects the laser beam collimated by the collimating lens 52 toward a measurement space by a rotating mirror surface (described later), and also emits the laser beam from an object. The reflected light is reflected. The lens 54 condenses the reflected light from the object reflected by the polygon mirror 53. The photodiode 55 has a plurality of pixels arranged in the Z direction and receives light collected by the lens 54. The motor 56 drives the polygon mirror 53 to rotate.

  The semiconductor laser 51 and the collimating lens 52 constitute an emission unit 501, and the lens 54 and the photodiode 55 constitute a light receiving unit 502. It is preferable that the optical axes of the light emitting unit 501 and the light receiving unit 502 are orthogonal to the rotation axis 530 of the polygon mirror.

  The box-shaped housing 57 is fixed to a part of the vehicle 100, for example. The housing 57 has an upper wall 57a, a lower wall 57b facing the upper wall 57a, and a side wall 57c connecting the upper wall 57a and the lower wall 57b. An opening 57d is formed in a part of the side wall 57c, and a transparent plate 58 is attached to the opening 57d.

  In the present embodiment, the polygon mirror 53 has a plurality (for example, eight) of mirror surfaces. The polygon mirror 53 is connected to a motor shaft 59 of a motor 56 fixed to the housing 57 and is driven to rotate. In the present embodiment, for example, the axis (rotation axis 530) of the motor shaft portion 59 extends in the vertical Z direction, and the XY plane formed by the X direction and the Y direction orthogonal to the Z direction is a horizontal plane. However, the axis of the motor shaft 59 may be inclined with respect to the vertical direction.

  The details of the polygon mirror 53 and the motor 56 will be described. FIG. 3 is a schematic sectional view of the polygon mirror 53 and the motor 56 shown in FIG. 1, and FIG. 4 is an enlarged sectional view of a portion A in FIG. 5 is a perspective view of the polygon mirror 53 shown in FIG. 4 as viewed from the bottom (Z direction). FIG. 6 is a perspective view of the pressing member shown in FIG. 4 as viewed from the bottom (Z direction). .

  As shown in FIG. 3, the polygon mirror 53 has a shape in which two quadrangular pyramids are joined in opposite directions to be integrated. Therefore, it has four pairs of mirror surfaces that are inclined in the direction facing each other. The pair of mirror surfaces includes a first mirror surface M1 and a second mirror surface M2, a third mirror surface M3 and a fourth mirror surface M4 (a surface not shown in FIG. 3), a fifth mirror surface M5 and a sixth mirror surface M6. , A seventh mirror surface M7 and an eighth mirror surface M8 (surfaces not shown in FIG. 3). The first mirror surface M1, the third mirror surface M3, the fifth mirror surface M5, and the seventh mirror surface M7 have different inclination angles with respect to the rotation axis 530 of the polygon mirror 53. Similarly, the second mirror surface M2, the fourth mirror surface M4, the sixth mirror surface M6, and the eighth mirror surface M8 have different inclination angles with respect to the rotation axis 530 of the polygon mirror 53. The tilt angle is an angle formed by an extension of each mirror surface and a portion where the extension intersects the rotation axis 530 of the polygon mirror 53. When each mirror surface is described generically or without distinction, it is referred to as a mirror surface M. These mirror surfaces M are formed by depositing a reflective film on the surface of a base made of a resin material (for example, PC (polycarbonate)) in the shape of the polygon mirror 53.

  As shown in FIG. 4, a support member 53 a connected to the motor shaft 59 is provided at the center of the polygon mirror 53 (the joint between the two quadrangular pyramids). As shown in FIG. 5, the inside of the polygon mirror 53 is hollow, and a plurality of grounding portions 53b that are in contact with the base member 59a of the motor shaft portion 59 are provided on the bottom surface of the support member 53a. The grounding portion 53b is a protruding portion whose cross section on the YZ plane is a hemisphere, a cone, a rectangle, or the like, and is provided with a plurality (at least three) on a concentric circle centering on the rotation shaft 530. Further, a through hole H1 is formed in the center of the support member 53a.

  The motor shaft portion 59 has a base member 59a and a motor shaft 59b, and transmits the rotation of the motor 56 to the polygon mirror 53. The base member 59a is attached to the motor 56 and comes into contact with the support member 53a of the polygon mirror 53. The motor shaft 59b is formed so as to protrude from the base member 59a along the direction of the rotation shaft 530, and penetrates through the through hole H1 of the support member 53a of the polygon mirror 53. Motor shaft portion 59 is preferably formed of a metal such as stainless steel, for example, but the material is not limited.

  The pressing portion 80 is in contact with the upper surface of the support member 53a and fixes the polygon mirror 53 to the motor shaft portion 59 by pressing the support member 53a toward the base member 59a along the rotation axis 530.

  The pressing portion 80 has a nut (fixed portion) 81, a washer 82, a spring (elastic member) 83, and a pressing member 84. A spiral groove (not shown) is formed outside the distal end of the motor shaft 59b, and the nut 81 is engaged with the motor shaft 59b and rotated by an operator, so that the nut 81 is mounted on the motor shaft 59b. Is moved linearly to a desired position. Washer 82 can be, for example, a flat washer. The nut 81 and the washer 82 are preferably formed of a metal such as stainless steel, for example, but the materials are not limited.

  With the lower end (one end) 83b in contact with the pressing member 84, the spring 83 is compressed by tightening the nut 81 and fixing the position of the upper end (other end) 83a in the direction of the rotation shaft 530. You. Thus, the spring 83 presses the polygon mirror 53 via the pressing member 84 with a restoring force corresponding to the position of the upper end portion 83a. The spring 83 may be, for example, a leaf spring made of stainless steel.

  The pressing member 84 has a central part 84a, a support part 84b, a ground part 84c, and a flat part 84d. A through hole H2 for passing the motor shaft 59b is formed in the center portion 84a, and the lower end portion 83b of the spring 83 is in contact with the through hole H2. The support portion 84b is formed in a wall shape along the direction of the rotation shaft 530 from the upper surface of the central portion 84a, and supports the spring 83 so as to be arranged along the motor shaft 59b. The holding member 84 is preferably formed of a metal such as aluminum or stainless steel, but may be formed of a resin having sufficient strength.

  As shown in FIG. 6, a cylindrical member corresponding to the support portion 84b is formed on the upper surface of the disk-shaped member corresponding to the central portion 84a and the flat portion 84d such that the central axes coincide. The center portion 84a is a range that includes a portion where the support portion 84b is formed from the outer edge of the through hole H2 in the above disk-shaped member, and the flat portion 84d is a portion where the support portion 84b is formed from the portion where the support portion 84b is formed. It is a range including up to the outer edge of the disk-shaped member. The ground portion 84c is an annular protrusion formed on the bottom surface of the central portion 84a and in contact with the support member 53a of the polygon mirror 53. The grounding portion 84c is not formed in an annular shape, but is a protruding portion whose cross section in the YZ plane is a hemisphere, a cone, a rectangle, or the like. You may. The support portion 84b and the ground portion 84c may be formed integrally with the center portion 84a and the flat portion 84d, or may be formed separately and connected.

  Returning to FIG. When the operator tightens the nut 81 to fix the polygon mirror 53 to the motor shaft portion 59 when assembling the optical scanning device 10, the flat portion 84d presses the flat portion 84d, so that the pressing member 84 Used to prevent rotation with rotation. The operator fixes the polygon mirror 53 to the motor shaft portion 59 by rotating the nut 81 while holding down the flat portion 84 d using a tool such as tweezers, for example. The flat portion 84d is located outside the central portion 84a and farther from the rotation shaft 530 than the position where the pressing member 84 contacts the polygon mirror 53 (the ground contact portion 84c) so that the operator can easily press the pressing member 84. Is formed. Therefore, when the operator tightens the nut 81, the external force applied to the polygon mirror 53 is limited by pressing the flat portion 84d. As a result, it is possible to prevent the polygon mirror 53 from being deformed due to an unnecessary external force.

  The operator tightens the nut 81 to a predetermined position where the polygon mirror 53 is fixed to the motor shaft 59 in a stable state without rattling.

  As described above, in the present embodiment, when the operator tightens the nut 81 to the predetermined position, the lower end portion 83b of the spring 83 comes into contact with the upper surface of the pressing member 84, and the upper end portion 83a of the spring 83 is fixed by the nut 81. The position in the direction of the rotation shaft 530 is fixed. As a result, the spring 83 is compressed, and presses the polygon mirror 53 via the pressing member 84 with a restoring force corresponding to the predetermined position. The polygon mirror 53 and the motor shaft portion 59 are in contact with the grounding portion 53b of the polygon mirror 53 at a base member 59a, and the pressing member 84 and the polygon mirror 53 are at a grounding portion 84c of the pressing member 84 and a supporting member 53a of the polygon mirror 53. Contact.

  The position P1 where the lower end 83b of the spring 83 contacts the pressing member 84 is closer to the rotation shaft 530 than the position P2 where the pressing member 84 contacts the supporting member 53a, and the position P2 is the position P3 where the base member 59a contacts the supporting member 53a. It is closer to the rotation axis 530 than it is. That is, the position P1, the position P2, and the position P3 are closer to the rotation shaft 530 in this order.

  By arranging the position P1 (the lower end portion 83b of the spring 83), the position P2 (the grounding portion 84c of the pressing member 84), and the position P3 (the grounding portion 53b of the polygon mirror 53) in such a manner, the pressing member 84 is supported. The stability of the member 53a and the base member 59a can be improved. For example, since the position P1 is closer to the rotation shaft 530 than the position P2, that is, the lower end portion 83b (action point) of the spring 83 is located inside the grounding portion 84c (fulcrum) of the pressing member 84, the lower end portion 83b The fluctuation of the holding member 84 with respect to the fluctuation of becomes smaller. Similarly, since the position P2 is closer to the rotation shaft 530 than the position P3, that is, the grounding portion 84c (action point) of the pressing member 84 is located inside the grounding portion 53b (fulcrum) of the polygon mirror 53, The variation of the base member 59a with respect to the variation of the member 53a is reduced. Therefore, the positions of the holding member 84, the support member 53a, and the base member 59a are firmly fixed without rattling.

<Modification>
Next, a modification of the holding member will be described. FIG. 7 is a diagram showing a modification of the holding member shown in FIG. 4, and FIG. 8 is a diagram showing another modification of the holding member shown in FIG.

  As shown in FIG. 7, the flat portion 85 d of the pressing member 85 is formed closer to the nut 81 than the supporting member 53 a of the polygon mirror 53. For example, the flat portion 85d is preferably formed outside the tip of the support portion 85b. Since the flat portion 85d is formed on the nut 81 side, the position of the flat portion 85d can be easily seen when an operator fixes the polygon mirror 53, so that the flat portion 85d of the pressing member 84 in FIG. Work becomes easy.

  Further, as shown in FIG. 8, the pressing member 86 does not have to include a supporting portion for supporting the spring 83. Accordingly, the structure of the pressing member 86 is simplified, and the manufacturing process of the pressing member 86 can be simplified. Further, the manufacturing cost of the pressing member 86 can be reduced.

  FIG. 9 is a cross-sectional view illustrating a case where a screw is used as a fixing portion. The polygon mirror 53 can be fixed to the motor shaft 59 using a screw 87 instead of the nut 81. In the case of this modification, a spiral groove (not shown) is formed inside the distal end portion of the motor shaft 59b, and is configured to engage with the screw 87.

  Although the embodiments to which the present invention is applied have been described, the present invention is not limited to these embodiments. The present invention can be variously modified based on the configurations described in the claims, and those modifications are also included in the scope of the present invention.

  For example, in the above-described embodiment, the pressing member 84 includes the grounding portion 84c between the pressing member 84 and the polygon mirror 53, and the polygon mirror 53 includes the grounding portion 53b between the polygon mirror 53 and the motor shaft portion 59. Has been described. However, the present invention is not limited to such a case. The polygon mirror 53 may include a grounding portion between the pressing member 84 and the polygon mirror 53, and the motor shaft portion 59 may include a grounding portion between the polygon mirror 53 and the motor shaft portion 59.

10 optical scanning device,
11 Emitter / receiver unit,
12 control part,
51 semiconductor laser,
52 collimating lens,
53 polygon mirror,
53a support member,
53b grounding part,
55 photodiodes,
56 motors,
57 housing,
58 transparent plate,
59 Motor shaft,
59a base member,
59b motor shaft,
61 motor encoder,
71 polygon mirror rotation angle detector,
80 pressing part,
81 nuts,
82 washers,
83 spring,
84 holding member,
84a central part,
84b support,
84c grounding part,
84d flat part,
120 buses,
530 Rotation axis of polygon mirror.

Claims (7)

An emission unit that emits laser light;
A polygon mirror unit comprising a plurality of mirror surfaces, configured to be rotatable around a rotation axis, and scanning the measurement space including the object by the reflected light of the laser light reflected by the mirror surface,
A light receiving unit that receives the reflected light reflected from the object,
A base member attached to a motor and in contact with the polygon mirror portion, and a motor shaft formed to protrude from the base member along the rotation axis and penetrate through the polygon mirror portion, wherein the rotation of the motor is A motor shaft transmitting to the polygon mirror,
A pressing portion that contacts the polygon mirror portion and presses the polygon mirror portion toward the base member along the rotation axis, thereby fixing the polygon mirror portion to the base member;
The pressing portion,
A fixing portion, an elastic member, and a holding member,
The fixed portion is engaged with the motor shaft and moved to a predetermined position on the motor shaft by being rotated,
In the elastic member, the position of the other end in the rotation axis direction is fixed by the fixing portion with one end in contact with the pressing member, and the polygon mirror portion is moved to the predetermined position via the pressing member. Press with the appropriate pressing force,
The position where the holding member contacts the polygon mirror portion is closer to the rotation axis than the position where the base member contacts the polygon mirror portion,
The light emitting and receiving unit, wherein a position at which one end of the elastic member contacts the pressing member is closer to the rotation axis than a position at which the pressing member contacts the polygon mirror portion. The holding member,
When the worker presses the polygon mirror portion to fix the polygon mirror portion to the base member by rotating the fixing portion, the pressing member is rotated by the rotation of the fixing portion. The light emitting and receiving unit according to claim 1, further comprising a flat portion used for prevention. The flat portion of the pressing member,
The light emitting and receiving unit according to claim 2, wherein the pressing member is formed at a position farther from the rotation axis than a position in contact with the polygon mirror unit.   4. The light emitting and receiving unit according to claim 1, wherein the polygon mirror unit has at least three protrusions that are equal in distance from the rotation axis and are in contact with the base member. 5.   The light emitting and receiving unit according to any one of claims 1 to 4, wherein the pressing member has an annular protrusion centered on the rotation axis and in contact with the polygon mirror.   The light emitting and receiving unit according to claim 1, wherein a base of the polygon mirror unit is formed of a resin. A light emitting and receiving unit according to any one of claims 1 to 6,
An optical scanning device comprising: a control unit configured to control the light emitting and receiving unit.