JP2009204916A - Two-axis driving device and light deflector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact two-axis driving device with superior response and a light deflector. <P>SOLUTION: The two-axis driving device is provided, which includes: a support pin 3 supporting a driven member 2; a fixing member 4 to which the support pin 3 is fixed; a magnetic driving part which rotates the driven member 2 with a part 3a of the support pin 3 as a fulcrum brought into contact with the driven member 2 and includes magnets 6 and coils 8; and encoders 9A9B optically detecting the amount of rotation of the driven member 2 by the magnetic driving part. One of the magnet 6 and the coil 8 is fixed to one of the driven member 2 and the fixing member 4. The other of the magnet 6 and the coil 8 is fixed to the other of the driven member 2 and the fixing member 4. The magnet 6 includes four magnet parts 6d<SB>1</SB>to 6d<SB>4</SB>arranged around the support pin 3. The two magnet parts at an opposite side with respect to the support pin 3 have the same directions of N-poles and S-poles. The neighboring two magnet parts around the support pin have opposite directions of the N-poles and the S-poles. The coil 8 is spaced apart from and disposed opposite to the magnet 6, wherein the number of the coils is a natural number multiple of 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a biaxial drive device and an optical deflection device.

  FIG. 12 is a perspective view of a conventional biaxial drive device. Reference numeral 100 denotes a first mirror, which is provided on the main shaft 101 and is rotationally driven by an actuator 102 that can drive only one axis. Reference numeral 103 denotes a second mirror, which is provided on the main shaft 104 and is rotationally driven by an actuator 105 that can drive only one axis. The directions in which the main shafts 101 and 104 extend are orthogonal. As described above, the biaxial drive device includes the scan unit including the first mirror 100 and the actuator 102 and the scan unit including the second mirror 103 and the actuator 105. By rotating the actuators 102 and 105 in conjunction with each other in these one set of scanning units, the light beam 106 from the light source is sequentially reflected by the first mirror 100 and the second mirror 103 and guided onto the scanning surface 107. The scanning surface is scanned two-dimensionally in the XY directions. This two-axis drive device has a problem that the positional relationship between the two actuators 102 and 105 needs to be strictly adjusted, and the two actuators 102 and 105 increase the size of the device.

On the other hand, Patent Documents 1 and 2 disclose an optical deflecting device that can provide a reflecting surface on the upper surface of a hemisphere to reflect a light beam at an arbitrary angle. Miniaturization is achieved by using one actuator. Patent Document 3 discloses a biaxial actuator that drives a mirror by a magnetic drive mechanism.
JP 2004-125896 A JP-A-11-149049 JP 2007-73133 A

  Patent Document 1 is a contact-type driving method in which a hemisphere is driven in contact with a mounting table, and the drive response is poor. Patent Document 2 is a non-contact driving method. In order to support the hemisphere in a non-contact manner with respect to the support, a dielectric liquid such as silicon oil is placed between the hemisphere and the support and on the mirror. Need to be filled. In this regard, Patent Document 3 does not require liquid using a magnetic drive mechanism, but the rotation center is away from the mirror, and the size reduction is insufficient.

  Accordingly, an object of the present invention is to provide a two-axis drive device and an optical deflection device that are small in size and excellent in responsiveness.

  A biaxial drive device according to one aspect of the present invention is a biaxial drive device that rotationally drives a driven member around each of two orthogonal axes, a support pin that supports the driven member, and the support pin A fixed member to which the driven member is fixed, a portion that contacts the driven member of the support pin to rotate the driven member, a magnetic drive unit including a magnet and a coil, and the driven member by the magnetic drive unit An encoder for optically detecting the amount of rotation of the magnet, wherein one of the magnet and the coil is fixed to one of the driven member and the fixed member, and the other of the magnet and the coil is the driven member The magnet has four magnet portions arranged around the support pin, and the two magnet portions on the opposite side with respect to the support pin have N pole and S pole. The direction is the same, Two magnet portions adjacent around lifting pins is opposite the direction of N and S poles, said coils faces away with the magnet, and which are located a natural number multiple number of 4.

  An optical deflecting device according to another aspect of the present invention includes a reflecting member having a reflecting surface that reflects an incident light beam, and the above-described biaxial driving device that drives the reflecting member as a driven object. And

  According to the present invention, it is possible to provide a two-axis drive device and an optical deflection device that are small in size and excellent in responsiveness.

  FIG. 1 is a cross-sectional view of the biaxial drive device of this embodiment. The biaxial driving device rotationally drives a mirror (reflection member) 2 that is a driven member. In this embodiment, the biaxial drive device is a part of the optical deflection device. The mirror 2 has a polygonal reflecting surface 2a that reflects the incident light beam 1 from an external light source, and a supported surface 2b as the back surface of the reflecting surface 2a. The reflective surface 2a is reflectively coated. The side surface of the mirror 2 is mirror-finished so as to serve as a parallel plate glass. The supported surface 2b of the mirror 2 is provided with a leaf spring, a bearing, or the like (not shown) so that it can rotate about two axes. Although the mirror 2 has a polygonal column shape, the shape such as a cylindrical shape is not particularly limited. A recessed portion 2c is formed in the supported surface 2b.

  The biaxial drive device includes a pivot support pin 3, a fixed yoke (fixed member) 4, a magnetic drive unit, and an encoder.

  The pivot support pin 3 is a rod-like or shaft member extending in the Z direction, and supports the mirror 2. The pivot support pin 3 has a tip portion 3a, a body portion 3b, and a terminal portion 3c.

  The tip portion 3a is a portion that fits into the concave portion 2c of the supported surface 2b of the mirror 2 and comes into contact with the mirror 2, and has a conical shape, a truncated cone shape, a polygonal pyramid shape, a hemispherical shape, and the like. By inserting the tip 3a into the recess 2c, the tip 3a can be connected even when the mirror 2 and the mirror 2 rotate. Further, depending on the shape of the tip portion 3a, the tip portion 3a can contact the supported surface 2b of the mirror 2 at a point contact or a minute region close thereto, and the mirror 2 can be rotated or inclined with the contact portion as a fulcrum. In this way, in this embodiment, the center of rotation of the mirror 2 is provided on the supported surface of the mirror 2, and the apparatus is made smaller than when both are separated. The shape and size of the recess 2c are set so that the mirror 2 can rotate with the tip 3a as a fulcrum. The body portion 3b has a cylindrical shape or a polygonal column shape, and the central axis coincides with the Z axis. Further, the pivot support pin 3 is inserted into and fixed to the concave portion 4b provided on the surface 4a of the fixed yoke 4 at the end portion 3c.

  The fixed yoke 4 is a flat plate member perpendicular to the Z-axis direction. The fixed yoke 4 is fixed to the mirror 2, and thus the pivot support pin 3 is also fixed to the mirror 2. The fixed yoke 4 is made of a ferromagnetic material. The fixed yoke 4 has a circular, rectangular, or polygonal shape when viewed from above, but the shape is not limited. The surface 4a of the fixed yoke 4 is provided with a recess 4b provided in the center and a mounting portion 4c. The recess 4 b has a shape that engages with the end portion 3 c of the pivot support pin 3. The mounting portion 4c is a portion to which the coil 8 is fixed, and is formed as a concave portion, a through hole, or other engaging portion.

  The magnetic drive unit has a yoke 5, a magnet 6 and a coil 8. The magnetic drive unit rotates the mirror 2 with a portion (tip portion 3a) of the pivot support pin 3 contacting the mirror 2 as a fulcrum. In the magnetic drive unit, the magnet 6 and the coil 8 are not in contact with each other, and the drive response is good and oil is not used.

  The yoke 5 is made of a ferromagnetic material and has a donut shape, a hollow disk shape, or a hollow frustum shape having a hollow hole 5a in the center. The yoke 5 is a flat plate member having an upper surface 5b fixed to the supported surface 2b of the mirror 2 and a lower surface 5c that is the back surface of the upper surface 5b. The lower surface 5c of the yoke 5 faces the fixing member 4 side. The pivot support pin 3 (the body portion 3b) is disposed in the hollow hole 5a. There is a certain gap G1 between the hollow hole 5a and the pivot support pin 3. Because of this gap G1, the yoke 5 can rotate around the pivot support pin 3 together with the mirror 2.

  A magnet 6 is attached to the lower surface 5 c of the yoke 5. The magnet 6 has a donut shape, a hollow disk shape, or a hollow frustum shape having a hollow hole 6a in the center. The magnet 6 has an upper surface 6b that is fixed to the lower surface 5c of the yoke 5, and a lower surface 6c that is the back surface of the upper surface 6b. The lower surface 6c of the magnet 6 faces the fixing member 4 side. The pivot support pin 3 (the body portion 3b) is disposed in the hollow hole 6a. There is a certain gap G2 between the hollow hole 6a and the pivot support pin 3. Due to this gap G 2, the magnet 6 can rotate around the pivot support pin 3 together with the yoke 5 and the mirror 2.

FIG. 2 is a schematic perspective view of the magnet 6. The arrow in the figure is the magnetic flux. As shown in the figure, the magnet 6 has four magnet portions 6d ₁ , 6d ₂ , 6d ₃ , 6d ₄ arranged around the pivot support pin 3. The magnet 6 shown in FIG. 2 is magnetized to four poles, but each magnet portion may be separated. The two magnet portions on the opposite side with respect to the pivot support pin 3, that is, the magnet portions in a positional relationship rotated by 180 ° in FIG. 2 have the same orientation of the N pole and the S pole. For example, the magnet portion 6d ₁ and the magnet portion 6d ₃ has S pole on the upper surface 6b side, there is a N pole on the lower surface 6c side. Further, the magnet portion 6d ₂ and the magnet portion 6d ₄ has N-pole on the upper surface 6b side, there is a S-pole on the lower surface 6c side. Further, two magnet portions adjacent to each other around the pivot support pin 3 have opposite directions of the N pole and the S pole. For example, the magnet portion 6d ₁ has S pole on the upper surface 6b side, there is a N pole on the lower surface 6c side, the magnet portion 6d ₂ has an N pole on the upper surface 6b side, there is a S-pole on the lower surface 6c side.

FIG. 3 is a schematic plan view of the coil 8. The coil 8 faces the magnet 6 and is arranged in a plane with a predetermined interval. The coil 8 is provided as a natural number multiple of four. Each coil 8 is formed by winding a coated wire covered with a heat-sealable resin around the outer periphery of the bobbin, forming it in a coil shape, placing it in a high temperature environment, melting the resin, and fixing each wire to a room temperature. It is an air core coil pulled out from the bobbin after returning. 1 and 3, 8a is a coil portion, and 8b is an air core portion. In FIG. 2, the coil 8 corresponding to the magnet portion having a positional relationship rotated by 180 ° is formed of a single wire and connected in series. The direction of the magnetic circuit (magnetic path) formed by the magnetic flux formed by each magnet portion is orthogonal to the winding direction of the coil 8. For this reason, an electromagnetic force can be generated when a current is passed through the coils 8 connected in series. Direction of the electromagnetic force is Z ₂ direction is downward in the Z ₁ direction or Z-direction is upward in the Z-direction. The mirrors 2 are tilted by generating opposite electromagnetic forces in the coils 8 arranged to face each other. For example, in FIG. 1, an electromagnetic force is generated in the Z2 direction in the left coil, and an electromagnetic force is generated in the Z1 direction in the right coil. The direction of the current flowing through the coil 8 at this time is also shown.

  A resin material 7 is fixed around the magnet 6 on the lower surface 5 c of the yoke 5. The resin material 7 has a hemispherical shape made of a nonmagnetic material, is made of resin, and has a bowl shape in which a circular portion 7a of the hemispherical body is opened. In the hemisphere, the side of the open circular portion 7 a faces the lower surface 5 c of the yoke 5, and the edge 7 b that defines the circular portion 7 a is fixed to the lower surface 5 c of the yoke 5.

  In this embodiment, the magnet 6 is fixed to the mirror 2 and the coil 8 is fixed to the fixed yoke 4. However, this may be reversed. That is, it is sufficient to fix one of the magnet 6 and the coil 8 to one of the mirror 2 and the fixed yoke 4 and the other of the magnet 6 and the coil 8 to the other of the mirror 2 and the fixed yoke 4.

  The resin material 7 has a hollow hole 7c at the bottom center. The pivot support pin 3 (the body portion 3b) is disposed in the hollow hole 7c. There is a certain gap G3 between the hollow hole 7c and the pivot support pin 3. Due to the gap G3, the resin material 7 can rotate around the pivot support pin 3 together with the mirror 2. In the present embodiment, the lengths of the gaps G1, G2, and G3 in the horizontal direction shown in FIG. 1 are set equal, but the present invention is not limited to this. The yoke 5, the magnet 6, the resin material 7 and the mirror 2 constitute an operating part. The moving part can be rotated about two axes by the pivot support pin 3.

  The encoder optically detects the amount of rotation of the mirror 2 by the magnetic drive unit. The encoder includes reading units 9A and 9B and an optical scale 10 formed on the surface of the spherical surface 7d of the hemisphere of the resin material 7 with brightness and darkness. The optical scale 10 includes a pair of patterns centered on two axes orthogonal to the Z direction of the hemisphere. A reading unit 9A or 9B is arranged in each pattern. The reading unit includes a light emitting element that irradiates light to the optical scale 10 and a light receiving element that receives light that interferes with the optical scale 10 and returns, and is arranged with a predetermined interval from the resin material 7. ing. The optical scale 10 is a lattice-like pattern having concentric reflecting portions and non-reflecting portions alternately.

  4A and 4B are side views of the resin material 7 and the reading units 9A and 9B. FIG. 4A shows a state before the mirror 2 rotates, and FIG. 4B shows a state after the mirror 2 rotates. The optical scale is provided on the outer periphery of the resin material 7 and is light and dark so that the reading unit can read the rotation amount when the mirror 2 is rotationally driven in the biaxial direction. The optical scale 10 forms a scale at the same pitch concentrically from the center of rotation about two axes. The reading units 9A and 9B are arranged at positions orthogonal to each other.

  As shown in FIG. 4B, the optical scale 10 is configured to be concentrically around the axis from the center of rotation so that the reading unit 9B and the optical unit orthogonal to each other even when the reading unit 9A is rotationally driven about the axis. The relationship with the scale 10 does not change. The optical scale 10 can be read even when the reading unit 9B side is driven to rotate about the axis.

  Here, the principle of the encoder will be described in more detail. FIG. 5 shows an optical scale for optically measuring the rotation direction and amount of rotation about two axes of an object composed of a part of a spherical surface such as a spherical body or a hemispherical body (hereinafter abbreviated as “spherical body”). It is a perspective view. The optical scale is formed on the surface of the spherical body 20 to be measured. The surface of the spherical body 20 is a metal specular reflection surface, and non-reflective portions 20a and 20b serving as a scale pattern are formed. At this time, the spherical body 20 is made of a metal having a metal mirror reflection surface, or a member provided with a reflection surface such as a metal reflection film on the surface or inside the hollow. Laser marking may be used to form the non-reflective portions 20a and 20b to be a scale pattern, or etching or the like may be used.

  FIG. 6 is a perspective view corresponding to FIG. 4A, and the optical scale 10 is distinguished into an optical scale pattern 10a for the reading unit 9A and an optical scale pattern 10b for the reading unit 9B. The optical scale patterns 10a and 10b are concentric patterns with the rotation axes 10c and 10d orthogonal to each other as the rotation center, and the reading units 9A and 9B are arranged with respect to the two axes to be measured. The radius of the concentric pattern as the scale pattern can be determined from the configuration of the photosensors of the reading units 9A and 9B and the radius of the spherical body.

  For example, as shown in FIG. 7, a case where a reading unit 13 including a point light source (light emitting element) 13a for illuminating with a divergent light beam and a light receiving element including a light receiving element 13b (detection pitch: P) is used. Think. Assuming that the scale pitch is Ps, interference fringes corresponding to twice the scale pitch Ps are formed on the light receiving element 13b. When the radius of the spherical body of the resin material 7 is R, the radius (Rs) of the concentric pattern that becomes the scale pattern can be set as follows with reference to FIG.

  Here, θ is an angle such that the scale pitch Ps satisfies Ps = P / 2. Further, in order to prevent the concentric circular patterns centering on the two rotation axes 10c and 10d perpendicular to each other from interfering with each other, the range of the concentric circular pattern is appropriately set for a desired movable range of each axis. You can also. If the pattern set as described above is used, it is possible to independently detect the amount of movement of each axis with respect to the biaxial rotational movement.

  That is, as shown in FIG. 6, with respect to rotation around the rotation axis 10c, the reading unit 9B reads the pattern 10b and detects the rotation direction and rotation amount around the rotation axis 10c. When the rotation is performed at an angle θa around the rotation axis 10c and further around the rotation axis 10d, the reading unit 9A can read the pattern 10a by using a concentric pattern as shown in FIG. it can. FIG. 9 is a diagram for explaining the operation of the encoder shown in FIG. 6, and is a cross-sectional view for explaining that the movement amounts of the respective axes are independently detected with respect to the rotational movement of the two axes. 9A is a cross-sectional view showing a state before the resin material 7 is rotated, and FIG. 9B is a cross-sectional view showing a state after the resin material 7 is rotated.

  When the radius of the patterns 10a and 10b read by the reading unit is reduced due to the rotation of the spherical body, it may be difficult to detect the rotation by the light receiving element 13b. For example, as shown in FIG. 10, by installing the reading units 9C and 9D at positions opposite to the reading units 9A and 9B by 180 °, the reading units 9A and 9B and the reading units 9C and 9D are switched appropriately. Range rotation detection can be performed. Here, FIG. 10 is a side view for explaining the expansion of the rotation detection range. FIG. 10A shows a state before rotation, and FIG. 10B shows a state after rotation.

  The reading units 9E and 9F can also be arranged inside a hollow spherical body 30 as shown in FIG. 11 a and 11 b are optical scale patterns corresponding to 10 a and 10 b, and are formed on the inner surface of the spherical body 30. Thereby, further space saving is possible. In this case, when a reflection film such as a metal thin film or a dielectric reflection film is provided inside the translucent spherical body and rotation is detected by an encoder from the outside of the spherical body, the surface of the spherical body 30 is mechanically worn. In this case, a stable encoder signal can be generated without being affected by the pattern itself.

  The encoder is not limited to the reflective type, and may be a transmissive type in which slits having a desired pitch are formed in a hollow spherical body.

  According to the present embodiment, it is possible to simultaneously drive and control two axial directions by one unit, and it is possible to reduce the size of the entire system as compared with the conventional system. In addition, since it is not necessary to position the two units strictly, the system construction time can be shortened.

It is sectional drawing of the biaxial drive device of a present Example. It is a schematic perspective view of the magnet of the biaxial drive device shown in FIG. It is a schematic plan view of the coil of the biaxial drive device shown in FIG. It is a side view of the resin material and reading part of the biaxial drive device shown in FIG. It is a perspective view explaining the principle of the encoder shown in FIG. It is a perspective view corresponding to the encoder of Fig.4 (a). It is a perspective view which shows the structure of the reading part of an encoder. It is the schematic for demonstrating the structure of the optical scale pattern of an encoder. It is sectional drawing explaining operation | movement of the encoder shown in FIG. It is a side view of the modification of the encoder shown in FIG. It is a perspective view of another modification of the encoder shown in FIG. It is a perspective view of the conventional biaxial drive device.

Explanation of symbols

1 Light beam 2 Mirror (reflective member, driven member)
3 Pivot support pin 4 Fixed yoke (fixed member)
5 yoke 6 magnets _6d 1 _{~6d 4} magnet unit 7 resin material 8 coils 9A-9F, 13 reading unit 10 optical scale 10a, 10b, 11a, 11b pattern 10c, 10d shaft 20,30 spherical body

Claims (3)

A biaxial drive device that rotationally drives a driven member around each of two orthogonal axes,
A support pin for supporting the driven member;
A fixing member to which the support pin is fixed;
Rotating the driven member around a portion of the support pin that contacts the driven member as a fulcrum, and a magnetic driving unit including a magnet and a coil;
An encoder that optically detects the amount of rotation of the driven member by the magnetic drive unit;
Have
One of the magnet and the coil is fixed to one of the driven member and the fixing member, and the other of the magnet and the coil is fixed to the other of the driven member and the fixing member,
The magnet has four magnet portions arranged around the support pin, and the two magnet portions on the opposite side with respect to the support pin have the same N-pole and S-pole orientations, The direction of the N pole and the S pole is opposite in the two adjacent magnet parts.
The two-axis drive device according to claim 1, wherein the coil is spaced apart from the magnet and provided with a natural multiple of four. The biaxial drive device includes:
A hemisphere that is fixed to the driven member and made of a non-magnetic resin;
The encoder is
An optical scale formed on the surface or the inner surface of the hemisphere as a concentric pattern around each of the two axes;
At least a pair of reading units each having a light emitting element that irradiates light, and a light receiving element that receives light from which the light from the light emitting element interferes with the optical scale,
The two-axis drive device according to claim 1, comprising: A reflecting member having a reflecting surface for reflecting the incident luminous flux;
The biaxial drive device according to claim 1 or 2, which drives the reflecting member as a driven member;
An optical deflecting device comprising: