JP2011197485A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner which can suitably perform stable optical scanning.SOLUTION: The optical scanner 10 includes a frame body 20, a swing part 12, a mirror part 14 having a reflective surface to reflect incident light, support parts 16a and 16b for supporting the swing part 12, a bearing 18 for attaching the supports 16a and 16b to the frame body 20, and a driving part 22 for swinging the reflective surface by rotating the swing part 12, the mirror part 14, and the support parts 16a and 16b. The swing part 12 includes the mirror part 14. The reflective surface includes a center axis L1 that becomes a center of rotation for swinging by the driving part 22 through the swing part 12 and the support parts 16a and 16b.

Description

  The present invention relates to an optical scanning device.

  Proposals related to optical scanning devices have been made (see, for example, Patent Document 1). For example, Patent Document 1 proposes a galvanometer mirror including a frame, a polarization plane, and two beam members as an optical scanning device. The polarization plane is a plane that reflects incident light. Both beam members support the polarization plane on the frame. Specifically, the deflection surface is supported by the frame body with a single beam member at the center of the left end. Further, the deflection surface is supported by the frame body with another beam member at the center of the right end. That is, the galvanometer mirror of Patent Document 1 scans light by driving the polarization plane around the axis of the two beam members collinear with the central axis of the member on which the polarization plane is formed.

JP 2009-244798 A (paragraph 0041, paragraph 0045, FIG. 2, FIG. 6, FIG. 7)

  By the way, in the optical scanning device, stable optical scanning must be suitably realized. Specifically, the incident light (beam) must be reflected in a predetermined direction without being so-called.

  An object of the present invention is to provide an optical scanning device capable of suitably performing stable optical scanning.

  One aspect of the present invention made in view of the above-described conventional problems includes a frame, a swing part, a mirror part having a reflection surface that reflects incident light, a support part that supports the swing part, An interposition part for attaching the support part to the frame, and a drive part for rotating the swinging part, the mirror part, and the support part to swing the reflecting surface; The reflection surface is a surface including a central axis that is a center of rotation for swinging by the driving unit through the swinging unit and the support unit. This is an optical scanning device. According to this, it is possible to reduce the occurrence of a phenomenon that light is scattered. Here, the fact that light is scattered refers to a phenomenon in which incident light does not enter the reflecting surface of the mirror part but passes through the vicinity of the reflecting surface. Note that the center of rotation for swinging is also the center of swinging.

  This optical scanning device can also be configured as follows. That is, the rocking part may include a flat surface, and the flat surface may be formed as the reflecting surface. According to this, the optical scanning device can have a simple configuration.

  Moreover, the said support part is a columnar member, Comprising: The said interposition part is comprised by the bearing with which the said support part of a columnar member is mounted | worn. According to this, rotation with a rocking | swiveling part, a mirror part, and a support part can be performed smoothly. Here, when the support portion is supported by the bearing, twisting of the support portion during swinging can be prevented. Therefore, at the time of swinging, no restoring force acts on the mirror part, and as a result, there is no resonance frequency associated with the rotation of the mirror part and the support part. Therefore, even when the optical scanning device is driven by a drive waveform such as a sawtooth waveform, ringing due to the resonance frequency, that is, fluctuation of the scanning light can be avoided.

  Further, the swinging portion and the support portion may be formed by an integral member. According to this, the optical scanning device can have a simple configuration. In addition, the center of rotation of the swinging portion, the mirror portion, and the support portion can be ensured with high accuracy.

  The driving unit includes an electromagnetic coil and a magnet provided at a position where a magnetic force can be applied to the electromagnetic coil, and either the electromagnetic coil or the magnet is provided in the swinging unit. It is good also as a feature. According to this, it is possible to preferably rotate the oscillating portion, the mirror portion, and the support portion to oscillate the reflecting surface.

  The mirror unit supports the mirror body having the reflection surface via a torsion shaft made of an elastic member, elastically deforms the torsion shaft in a resonance state, and swings the mirror body by the drive unit. The mirror unit may include a structure that swings in a direction orthogonal to the direction. According to this, light can be scanned in two orthogonal directions. That is, light can be scanned two-dimensionally.

  According to the present invention, an optical scanning device capable of suitably performing stable optical scanning can be obtained.

It is a perspective view of an optical scanning device. (A) shows the reflection state of light in the optical scanning device to be compared, and (b) shows the reflection state of light in the optical scanning device of this embodiment. (A) is a plan view of another optical scanning device, and (b) is a front view of another optical scanning device. (A) is a top view of the mirror part with which the other optical scanning device shown in FIG. 3 is equipped, (b) is KK sectional drawing of Fig.4 (a).

  Embodiments for carrying out the present invention will be described below in detail with reference to the drawings. The present invention is not limited to the configurations described below, and various configurations can be employed in the same technical idea. For example, some of the configurations described below may be omitted or replaced with other configurations. Moreover, you may make it include another structure.

  The optical scanning device 10 of this embodiment is a device that scans light incident from an external light source. The optical scanning device 10 is employed in various optical devices. For example, it is employed in a retinal scanning head-mounted display. As shown in FIG. 1, the optical scanning device 10 includes a swing part 12, a mirror part 14, support parts 16 a and 16 b, two bearings 18, a frame body 20, and a drive part 22.

  In the optical scanning device 10, the oscillating portion 12, the mirror portion 14, and the support portions 16 a and 16 b constitute an integral shaft portion 24. The oscillating portion 12 uses a single cylindrical member as a raw material, and the central portion of the direction of the central axis L1 (hereinafter, the direction of the central axis L1 is also referred to as “axial direction”) is the central axis L1. In a direction perpendicular to the axial direction in the same plane (see “axial vertical direction” in FIG. 1; hereinafter, also referred to as “axial vertical direction”), it is formed by machining a predetermined width horizontally. Yes. In order to form the oscillating portion 12, the central portion of a single material is processed into a concave shape by a depth corresponding to the dimension of the radius of the cylinder from the outer peripheral surface of the cylinder toward the central axis L1. For example, cutting and polishing, forging or etching. Accordingly, the swinging portion 12 has a semicircular cross section perpendicular to the axial direction. The shaft portion 24 is made of a metal material such as stainless steel such as SUS304 or SUS430, titanium, or iron.

  A plane that forms the swinging portion 12 that is formed horizontally is a plane that includes the central axis L <b> 1 of the shaft portion 24. Moreover, the plane which comprises the rocking | swiveling part 12 is finished in a mirror surface state by mirror polishing. That is, the plane that forms the oscillating portion 12 constitutes the mirror portion 14 and serves as a reflecting surface of the mirror portion 14. Therefore, the reflecting surface of the mirror portion 14 is a plane including the central axis L1 of the shaft portion 24. The mirror unit 14 reflects light incident on the reflecting surface in a predetermined direction.

  The support portions 16 a and 16 b are formed on both end sides of the swing portion 12 in the axial direction of the shaft portion 24. The shaft portion 24 is formed so that the swinging portion 12 in which the mirror portion 14 is formed is sandwiched between the support portions 16a and 16b. The support parts 16a and 16b are attached to the frame body 20 via a bearing 18 as an interposition part. For example, a ball bearing is employed as the bearing 18. However, other configurations such as a resin bearing using a resin material having a small friction coefficient such as Teflon (registered trademark) may be adopted as the bearing 18. In addition, the shaft part 24 is good also as a structure which assembled | assembled integrally the rocking | swiveling part 12 and support part 16a, 16b which were each comprised as a separate member so that it might become the positional relationship mentioned above. Further, in FIG. 1, the bearing 18 on the support portion 16a side is in a state of being hidden by the frame body 20, and the illustration thereof is omitted.

  The frame 20 forms a skeleton of the optical scanning device 10. The frame body 20 has a concave shape when viewed from the direction perpendicular to the axis in FIG. Each component is directly or indirectly attached to the frame body 20 and supported by the frame body 20. For example, a through-hole penetrating in the direction of the central axis L1 is formed in each of the side wall portions 20a and 20b of the frame body 20 around the central axis L1. A bearing 18 is attached to these through holes. The support portions 16a and 16b are supported by a bearing 18 attached to the side wall portions 20a and 20b.

  The drive part 22 rotates the shaft part 24 attached to the frame 20 via the bearing 18 so as to reciprocate within a predetermined range about the central axis L1. In addition, the arrow of the circular-arc-shaped arrow centering on the central axis L1 shown in FIG. 1 shows the rotation direction of the shaft part 24. As shown in FIG. The drive unit 22 is an electromagnetic drive mechanism. The drive unit 22 includes an electromagnetic coil 224 and a magnet 226. For example, the electromagnetic coil 224 is provided on the back surface of the reflection surface of the mirror portion 14, that is, the portion of the swinging portion 12 that faces the reflection surface of the mirror portion 14 with the swinging portion 12 interposed therebetween. Specifically, flat plates 228a and 228b are provided on both sides of the swing portion 12 in the direction perpendicular to the axial center, and the electromagnetic coil 224 has a lower surface side of the flat plates 228a and 228b (see the arrow “down” shown in FIG. 1), that is, It is installed on the surface on the magnet 226 side. The electromagnetic coil 224 is wound in a predetermined direction. The magnet 226 is installed on the frame 20 so as to be close to and opposed to each of the electromagnetic coils 224.

  When a current is passed through the electromagnetic coil 224, a magnetic force is generated in the electromagnetic coil 224. The shaft portion 24 reciprocates around a predetermined range around the central axis L1 by the magnetic force of the electromagnetic coil 224 and the magnetic force of the magnet 226. The reciprocating rotation causes the reflecting surface of the mirror unit 14 to swing in the rotational direction. Here, since the reflecting surface of the mirror portion 14 is a surface including the central axis L1, the swinging of the reflecting surface of the mirror portion 14 is also performed around the central axis L1. In addition to the electromagnetic system as described above, the driving unit 22 can employ various systems such as an electrostatic system or a piezoelectric system. It is determined which method is used in consideration of various points. The electromagnetic method is preferable in that a configuration such as a modified example described later can be adopted.

  Here, in the optical scanning device 10, since the shaft portion 24 is supported by the bearing 18 attached to the support portions 16a and 16b, the shaft portion 24 is not twisted at the time of swinging, and the restoring force due to the twist is not generated. . Therefore, in the optical scanning device 10, the resonance state accompanying the rotation of the shaft portion 24 is not achieved. Therefore, in the optical scanning device 10, even when the optical scanning device 10 is driven by a drive waveform such as a sawtooth waveform, ringing due to the resonance frequency of the optical scanning device 10, that is, fluctuation of scanning light can be avoided.

  Next, an advantageous effect obtained by the optical scanning device 10 will be described with reference to FIGS. Hereinafter, an optical scanning device in which the central axis that is the center of rotation for swinging is not included in the reflection surface of the mirror unit will be described as a comparison target. Note that the optical scanning device to be compared is also referred to as a “comparison device”. In the comparison device, the same reference numerals as those used in the configuration of the optical scanning device 10 are used for the same or similar configuration as the configuration of the optical scanning device 10. In FIGS. 2A and 2B, the mark with “+” in “◯” is the center of rotation of the mirror section 14 and the center of oscillation of the reflecting surface.

  As is clear from FIG. 2A for the comparison device and FIG. 2B for the optical scanning device 10, the reflecting surface of the mirror portion 14 is indicated by a dotted line in FIGS. 2A and 2B. In the comparison state and the optical scanning device 10, the reflection state of the light incident from the positions A, B, and C is the same. That is, the entire incident light is reflected by the reflecting surface.

  When the mirror unit 14 is rotated by a predetermined angle θ and the reflection surface is in a solid line state shown in FIGS. 2A and 2B, in the comparison device, light incident from positions A and B is reflected on the reflection surface. Although reflected, the light incident from the position C does not enter the reflecting surface and passes through the position where the reflecting surface exists, as shown in the R part of FIG. That is, in the comparison device, a state where light is emitted occurs. On the other hand, in the optical scanning device 10, the phenomenon as in the comparison device does not occur, and the entire incident light is reflected by the reflecting surface.

  Therefore, the optical scanning device 10 can reduce the occurrence of a phenomenon that light is emitted compared to the comparison device. In this respect, the optical scanning device 10 can preferably realize stable optical scanning as compared with the comparison device. In a situation where the size of the reflecting surface of the mirror unit 14 cannot be increased due to the problem of the space where the optical scanning device is installed, the configuration like the optical scanning device 10 can reflect a wide range of incident light. Particularly advantageous.

  The configuration of the present embodiment can also be as follows. That is, in the above, as shown in FIG. 1, the shaft portion 24 constituted by the swinging portion 12 including the mirror portion 14 and the support portions 16a and 16b has the bearing 18 mounted on the support portions 16a and 16b. An example of the optical scanning device 10 that is supported on both sides through the above is described. In addition, an optical scanning device in which a bearing is mounted on any one of the support portions and the shaft portion is cantilevered can be provided. Also with such an optical scanning device, as in the optical scanning device 10, the light reflection state shown in FIG. 2B can be realized. When the optical scanning device is cantilevered, the shape may be different from that of the shaft portion 24 of the optical scanning device 10. The configuration of the optical scanning device 10 shown in FIG. 1 will be described as an example. Of the support portions 16a and 16b formed on both ends of the swinging portion 12, the support portion 16a or the support portion 16b to which the bearing 18 is not mounted is omitted. Alternatively, the shaft portion may have a different shape. In this case, a through hole for attaching the bearing 18 is omitted in the side wall 20a or the side wall 20b of the frame 20 on the side where the bearing 18 is omitted.

  In the above description, as illustrated in FIG. 1, the optical scanning device 10 in which the plane formed on the swinging portion 12 is configured as the mirror portion 14 has been described as an example. In addition, the optical scanning device 10 may be the optical scanning device 50 shown in FIGS. The optical scanning device 50 will be described with reference to FIGS. 3 (a) and 3 (b) and FIGS. 4 (a) and 4 (b). In the following description, in the optical scanning device 50, the same reference numerals as those used in the configuration provided in the optical scanning device 10 are used for the same or similar configuration as the configuration provided in the optical scanning device 10. The description of the configuration of the optical scanning device 50 that is the same as or similar to that of the optical scanning device 10 is omitted.

  Similar to the optical scanning device 10, the optical scanning device 50 includes an oscillating portion 52, a mirror portion 54, support portions 16 a and 16 b, two bearings 18, a frame body 20, and a drive portion 22. In the optical scanning device 50, the swinging part 52 and the support parts 16a and 16b constitute an integral shaft part 64. The oscillating part 52 is formed by the same method as the oscillating part 12. The oscillating portion 52 uses a single cylindrical member as a raw material, and the central portion of the direction of the central axis L2 of the raw material (hereinafter, the direction of the central axis L2 is also referred to as “axial direction”) is the central axis L2. In a direction perpendicular to the axial direction within the same plane (see “axial vertical direction” in FIG. 4A, hereinafter also referred to as “axial vertical direction”), and processed horizontally by a predetermined width. Is formed.

  In order to form the oscillating portion 52, the central portion of a single material is processed into a concave shape deeper than the depth corresponding to the dimension of the radius of the cylinder from the outer peripheral surface of the cylinder toward the central axis L2. That is, as will be described later, in a state in which the mirror portion 54 is fixed to the swinging portion 52, the mirror 54 is processed to a depth such that the reflection surface of the mirror portion 54 is a surface (plane) including the central axis L2. In the oscillating portion 52, the flat surface formed by processing horizontally is not polished to be a mirror surface. In the optical scanning device 50, a step portion 522 including a horizontal plane parallel to the axial direction (hereinafter also referred to as “mounting surface”) is formed in the boundary portion D with the support portion 16 a in the swinging portion 52. Is done. The mirror portion 54 is fixed to the mounting surface of the step portion 522 in a cantilevered state. For this fixing, for example, an adhesive, welding using a laser, clamping using a predetermined fastener, or the like is used. In a state of being fixed to the mounting surface of the stepped portion 522, the mirror portion 54 is fixed so that the reflection surface faces upward (see the arrow “up” shown in FIG. 3B).

  The shaft portion 64 in which the swinging portion 52 to which the mirror portion 54 is fixed and the support portions 16a and 16b are integrally formed is the side wall portion 20a of the frame body 20 via the bearings 18 as in the optical scanning device 10. , 20b are rotatably mounted. In addition, the shaft part 64 is good also as a structure which assembled | assembled integrally the rocking | swiveling part 52 and support part 16a, 16b respectively comprised as a separate member similarly to the shaft part 24. FIG. In the optical scanning device 50, the drive unit 22 is installed in the same state as the optical scanning device 10 using flat plates 228a and 228b. Therefore, when the drive unit 22 is driven in a state of being attached to the frame body 20, the shaft portion 64 reciprocates within a predetermined range around the central axis L2. The rotation direction of the shaft portion 64 is the same as that of the optical scanning device 10. Therefore, the reflecting surface of the mirror portion 54 fixed to the swinging portion 52 is swung in the rotation direction around the central axis L2 as the shaft portion 64 reciprocates around the central axis L2.

  The mirror unit 54 is configured by a piezo-type mirror unit such as an optical scanner described in JP-A-2006-293116. As shown in FIGS. 4A and 4B, the mirror portion 54 has a base body 70, a mirror main body 72, torsion shafts 74a and 74b, an extended end portion 75, and a piezo element 76. including. The base portion 70 is formed with ear portions 702a and 702b. A piezo element 76 is fixed to the base portion 70. Each of the ear portions 702a and 702b is opposite to the portion of the base portion 70 fixed in contact with the step portion 522 (for example, see the portion in contact with the step portion 522 indicated by a two-dot chain line in FIG. 4B). It is formed so as to extend to the right side in the axial direction (see the arrow “right” shown in FIG. 4) from the part and the part that is on both sides of the base part 70 in the direction perpendicular to the axial center. The ear portions 702a and 702b are arranged in a positional relationship facing each other.

  The extended end portion 75 connects the right end portions of the ear portions 702a and 702b in the axial direction in the axial direction. An opening 78 is formed by the base portion 70, the ear portions 702a and 702b, and the extended end portion 75. The opening 78 becomes a space for installing the mirror main body 72. The mirror body 72 reflects light incident on the reflecting surface in a predetermined direction. As shown in FIG. 4A, the torsion shafts 74a and 74b are connected to the ear portions 702a and 702b, respectively. The torsion shafts 74a and 74b are formed so as to divide the opening 78 in the axial direction, and are formed from the ears 702a and 702b toward the central axis L2 in the vertical direction to support the mirror main body 72. . In the cantilevered mirror portion 54, the mirror main body 72 supported by the torsion shafts 74a and 74b is lifted from the horizontal plane of the swinging portion 52. The base portion 70 is made of a conductive material having elasticity, specifically, a metal material such as stainless steel such as SUS304 or SUS430, titanium, or iron.

  The piezoelectric element 76 is deformed when a predetermined voltage is applied. In the structure constituting the mirror unit 54, a resonance state is formed by repeatedly turning on and off the voltage to the piezo element 76 and repeatedly deforming the piezo element 76. Therefore, the piezo element 76 functions as a drive source for forming a resonance state. The voltage on / off of the piezo element 76 is performed at a timing according to the resonance frequency of the structure.

  As described above, the mirror portion 54 having such a configuration is fixed to the stepped portion 522 so that the reflection surface of the mirror main body 72 is a surface including the central axis L2. In the mirror section 54, with the repeated deformation of the piezo element 76, a standing wave is generated with the fixed position of the stepped section 522 and the mirror section 54 as a fixed end and the swing axis L <b> 3 of the mirror body 72 as a node. This standing wave induces torsional vibration around the oscillation axis L3 with respect to the torsion axes 74a and 74b. And the mirror main body 72 reciprocates in the direction of the arrow shown in FIG. The reflecting surface of the mirror body 72 swings in this vibration direction (rotation direction). In addition, the two mirror main bodies 72 shown with a dashed-two dotted line in FIG.4 (b) show the mirror main body 72 in the state which vibrated in each direction.

  Here, the swinging direction by the structure including the mirror portion 54 is orthogonal to the swinging direction about the central axis L2 by the driving unit 22. Therefore, in the optical scanning device 50, the reflecting surface of the mirror portion 54 (mirror body 72) can be swung in two directions orthogonal to each other, and incident light can be scanned in a two-dimensional direction. The optical scanning device 50 may also be configured such that the shaft portion 64 is cantilevered as described above.

DESCRIPTION OF SYMBOLS 10,50 Optical scanning device 12,52 Oscillating part 14,54 Mirror part 16a, 16b Support part 18 Bearing 20 Frame body 22 Drive part

Claims (6)

A frame,
A rocking part;
A mirror portion having a reflecting surface for reflecting incident light;
A support part for supporting the rocking part;
An interposition part for attaching the support part to the frame;
A drive unit that rotates the swinging unit, the mirror unit, and the support unit to swing the reflecting surface;
The swing part includes the mirror part,
The optical scanning device according to claim 1, wherein the reflection surface is a surface including a central axis that passes through the swinging portion and the support portion and serves as a center of rotation for swinging by the driving portion.   The optical scanning device according to claim 1, wherein the oscillating portion includes a flat surface, and the flat surface is formed as the reflecting surface. The support part is a columnar member,
The optical scanning device according to claim 1, wherein the interposition part is configured by a bearing attached to the support part of a columnar member.   4. The optical scanning device according to claim 1, wherein the swinging portion and the support portion are formed by an integral member. 5. The drive unit includes an electromagnetic coil and a magnet provided at a position where a magnetic force can act on the electromagnetic coil,
5. The optical scanning device according to claim 1, wherein either the electromagnetic coil or the magnet is provided in the swinging portion. 6.   The mirror unit supports a mirror body having the reflecting surface via a torsion shaft made of an elastic member, elastically deforms the torsion shaft in a resonance state, and moves the mirror body in a swinging direction by the drive unit. 6. The optical scanning device according to claim 1, wherein the optical scanning device is configured by a mirror unit including a structure that swings in an orthogonal direction. 7.

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