JP2010107666A - Optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic resonant optical scanner capable of achieving reduction in size and obtaining a large two-dimensional deflection angle by producing high torque two-dimensionally. <P>SOLUTION: In the optical scanner 1, wherein optical scanning is carried out by reflecting incident light on a reflection plane of a movable part 30 supported rotationally by a fixed part 10, the movable part 30 turns with the reflection plane by a two-axis gimbal mechanism, while the fixed part 10 generates electromagnetic torque for turning the movable part 30 by combination of steady magnetic flux generated by a permanent magnet and driving magnetic flux generated by feeding current through a coil. The driving magnetic flux generating electromagnetic torque around the y-axis occurs when alternating voltage of a frequency meeting a resonant frequency of the movable part 30 is applied to the coil. The driving magnetic flux generating electromagnetic torque around the x-axis occurs when gradually varying direct voltage is applied to the coil. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electromagnetic resonance type optical scanner, and more particularly to a technique capable of scanning light two-dimensionally by vibrating a mirror using electromagnetic force and torsional resonance of a leaf spring. It is.

  An optical scanner is a device that scans light such as laser light, and is widely applied to barcode readers, laser printers, measuring instruments, displays, and the like. Optical scanners can be classified into three types: a polygon mirror type, a MEMS (Micro Electro Mechanical Systems) type, and a resonance type, depending on the driving method of a mirror that scans light.

  The polygon mirror type is a system in which light is scanned by rotating, with a motor, a mirror that is cut, polished, and coated on a polyhedron parallel to the rotation axis of an aluminum plate or glass plate, and each surface has a reflective surface. . The maximum deflection angle and scanning frequency depend on the number of reflecting surfaces of the mirror if the rotation speed of the motor is constant. Polingon mirror type optical scanners are currently most widely used due to their excellent maximum deflection angle and scanning frequency. However, since a motor is used, there is a problem that there is a limit to miniaturization and power saving.

The MEMS type is a driving method mainly using an electrostatic force. The MEMS type is very effective for miniaturization by MEMS technology. However, since the MEMS type optical scanner cannot obtain a large torque, there is a problem that the deflection angle is small, that is, it is difficult to obtain a large light scanning angle.
The resonance type is a method of scanning light by vibrating (rotating) a mirror using a resonance phenomenon caused by a torsional motion of a leaf spring. The resonance type has advantages such as a long life because it is smaller and consumes less power and has less frictional parts than the polygon mirror type that rotates the motor. For example, Patent Document 1 describes an electromagnetic resonance type optical scanner that is reduced in size and weight. However, although the resonance type is superior to the MEMS type in deflection angle, it cannot take a large value. Further, in the optical scanner described in Patent Document 1, because of the structure, the gap between the movable portion and the fixed portion increases with an increase in the rotation angle. It is difficult to ensure a deflection angle.

  In the future, an optical scanner capable of scanning from one dimension to two dimensions is highly expected. At present, a method of scanning light using a polygon mirror with two motors is common.

  FIG. 5 is a diagram showing a configuration of a conventional polygon mirror type two-dimensional scanning optical scanner.

  As shown in FIG. 5, a conventional polygon mirror type two-dimensional scanning optical scanner is arranged such that a mirror 102 rotated by a motor 103 and a mirror 104 rotated by a motor 105 are opposed to each other. The laser beam from the laser 101 is emitted to the reflecting surface of the mirror 102. According to this configuration, the number of reflecting surfaces of the mirror 102 and the mirror 104 is appropriately set, and the number of rotations of the motor 103 and the motor 105 is controlled, so that the laser beam can be scanned two-dimensionally. Yes.

  However, since the polygon mirror type two-dimensional scanning optical scanner as described above uses the two motors 103 and 105, the size and power consumption are further increased.

  On the other hand, in a MEMS type optical scanner or the like, a configuration capable of two-dimensional scanning has been developed. As a MEMS type two-dimensional scanning optical scanner, for example, Patent Document 2 describes a galvanometer mirror applied to a laser beam scanning system or the like.

  FIG. 6 is a diagram showing a configuration of a conventional MEMS type two-dimensional scanning optical scanner.

  As shown in FIG. 6, the conventional MEMS type two-dimensional scanning optical scanner includes a mirror 111, four permanent magnets 112 to 115, four torsion bars 116 to 119, a fixed plate 120, an outer movable plate 121, and an inner side. The movable plate 122 is configured. The mirror 111 is provided on the inner movable plate 122.

According to this configuration, Lorentz force is generated, and the torsion bars 116 and 118 repeat torsional motion, so that the inner movable plate 122 vibrates, and thus the mirror 111 vibrates. In addition, Lorentz force is generated, and the torsion bars 117 and 119 repeat torsional motion, so that the outer movable plate 121 vibrates and thereby the mirror 111 vibrates. As described above, each of the torsion bars 116 to 119 repeats torsional motion, so that the mirror 111 can be vibrated in two dimensions.
JP 2007-94109 A (released on April 12, 2007) Japanese Patent Laid-Open No. 7-175005 (published July 14, 1995)

  However, the conventional MEMS type two-dimensional scanning optical scanner can be reduced in size as compared with the conventional polygon mirror type two-dimensional scanning optical scanner, but the torque is the same as in the one-dimensional scanning. Since it is small, the problem that the deflection angle is small remains. Further, the MEMS type optical scanner has a problem that a ferromagnetic material cannot be incorporated.

  Therefore, there is a demand for the development of an optical scanner that can incorporate a ferromagnetic material, realizes downsizing, and can vibrate a mirror two-dimensionally with a large deflection angle.

  The present invention has been made in view of the above-described conventional problems, and an object thereof is to obtain a large two-dimensional deflection angle by realizing downsizing and generating a high torque in two dimensions. It is an object of the present invention to provide an electromagnetic resonance type optical scanner.

  In order to solve the above problems, the optical scanner of the present invention is a light scanner that scans light by reflecting incident light on a reflecting surface of a movable part rotatably supported by a fixed part. It has a configuration that rotates together with the reflecting surface by a biaxial gimbal mechanism, and the fixed portion is movable by combining a stationary magnetic flux generated by a permanent magnet and a driving magnetic flux generated by passing a current through a coil. The drive magnetic flux that generates the electromagnetic torque that rotates the movable part about one axis is configured to generate an electromagnetic torque that rotates the moving part, and an AC voltage having a frequency that matches the resonance frequency of the movable part is applied to the coil. The driving magnetic flux that is generated when applied and generates the electromagnetic torque that rotates the movable part about the other axis is applied to the coil with a DC voltage that changes stepwise. It is characterized by being generated by Rukoto.

  According to the above configuration, the driving magnetic flux generated by passing a current through the coil cancels and weakens when generated in the opposite direction to the stationary magnetic flux generated by the permanent magnet, and the stationary magnetic flux generated by the permanent magnet If they occur in the same direction, they will be combined and become stronger. Therefore, the suction force between the movable part and the fixed part increases on the one hand and decreases on the other hand. Thereby, electromagnetic torque is generated and the movable part rotates.

  Moreover, since the drive magnetic flux which generates the electromagnetic torque for rotating the movable part on one axis is generated when an AC voltage is applied to the coil, the generation direction is alternately switched. Thereby, a movable part repeats a twist motion. Since the frequency of the AC voltage is adjusted to the resonance frequency of the movable part, the movable part performs resonance driving, so that the rotation angle (deflection angle) can be amplified.

  The drive magnetic flux that generates the electromagnetic torque that rotates the movable part on the other axis is generated by applying a DC voltage that changes stepwise to the coil, so the direction of generation is constant and the strength of the magnetic flux increases stepwise. Change. Thereby, a movable part rotates in steps.

  As described above, when the movable portion rotates in a two-dimensional manner at a large angle, the reflecting surface can also rotate in a two-dimensional manner at a large angle. Further, as compared with a conventional polygon mirror type two-dimensional optical scanner, since a motor is not used, the size can be reduced. Therefore, it is possible to obtain a large two-dimensional deflection angle by realizing miniaturization and generating a high torque in two dimensions.

  In order to solve the above-described problem, the optical scanner of the present invention is an optical scanner that scans light by reflecting incident light on a reflecting surface of a movable part that is rotatably supported by a fixed part. The first rotation axis is rotated by a gimbal mechanism in which a first rotation axis rotated by a torsion bar and a second rotation axis orthogonal to the first rotation axis and rotated by another torsion bar are on the same plane, and the first rotation A magnetic plate formed so as to include an orthogonal point between the shaft and the second rotation axis, and the reflective surface provided on the magnetic plate, and is configured such that the center of gravity is located at the orthogonal point. The fixing portion has the orthogonal point located on its own central axis, the first rotation axis located on a first plane including the central axis, the central axis and orthogonal to the first plane. When the second rotation axis is located on the second plane In addition, the magnetic support column that rotatably supports the movable part, and a permanent member fixed to the surface of the magnetic support column opposite to the side supporting the movable part so that the reflection surface is exposed to the upper side. The magnet has a U-shaped cross-sectional shape with an open upper side symmetrical with respect to the central axis on the first plane, and an upper side with an open upper side symmetrical with respect to the central axis on the second plane. A cross-sectional shape of the first plane of the magnetic body main body having a letter-shaped cross-sectional shape, and a magnetic body main body to which the permanent magnet is fixed so that the magnetic pillar is positioned on the upper side; The first coil wound around the magnetic body so as to generate a first magnetic flux that passes through the portion that forms a portion, and a current flows through the portion that forms the cross-sectional shape of the second plane of the magnetic body. The magnetic field is generated so as to generate the second magnetic flux. A second coil wound around the body body, the first coil being supplied with an AC voltage having a frequency in accordance with the resonance frequency of the movable part, and the second coil being changed in a stepwise manner. It is characterized by being given a voltage.

  According to the above configuration, the magnetic body is formed with magnetic poles at positions symmetrical with respect to the central axis on the first plane by the permanent magnet, and at positions symmetrical with respect to the central axis on the second plane. A magnetic pole is formed. As a result, on the first plane, magnetic flux in a direction from the permanent magnet to the magnetic pole via the magnetic column and the movable part in sequence is generated symmetrically with respect to the central axis. In the second plane, the magnetic flux in the direction from the permanent magnet to the magnetic pole via the magnetic support column and the movable part is generated symmetrically with respect to the central axis. Therefore, the first magnetic flux and the second magnetic flux are generated in a state where the magnetic flux is generated by the permanent magnet.

  Here, in the first plane, since the magnetic body has a U-shaped cross-sectional shape with the upper left and right sides symmetrical with respect to the central axis, the first magnetic flux is generated by the magnetic body and the movable body. Generated through the part. For this reason, the first magnetic flux generated by the coil cancels out the magnetic flux generated by the permanent magnet on one side and becomes weaker and becomes stronger in combination with the magnetic flux generated by the permanent magnet on the other side. Therefore, the suction force between the movable part and the fixed part increases on the one hand and decreases on the other hand. Thereby, electromagnetic torque is generated and the movable part rotates.

  Further, since the first magnetic flux is generated when an AC voltage is applied to the first coil, the generation direction is alternately switched. Thereby, a movable part repeats a twist motion. Since the frequency of the AC voltage is adjusted to the resonance frequency of the movable part, the movable part performs resonance driving, so that the rotation angle (deflection angle) can be amplified.

  Also in the second plane, the movable portion rotates on the same principle. Since the second magnetic flux is generated when a DC voltage that changes stepwise is applied to the second coil, the generation direction is constant and the strength of the magnetic flux changes stepwise. Thereby, a movable part rotates in steps.

  As described above, when the movable portion rotates in a two-dimensional manner at a large angle, the reflecting surface can also rotate in a two-dimensional manner at a large angle. Further, as compared with a conventional polygon mirror type two-dimensional optical scanner, since a motor is not used, the size can be reduced. Therefore, it is possible to obtain a large two-dimensional deflection angle by realizing miniaturization and generating a high torque in two dimensions.

  In the optical scanner of the present invention, the inner surface parallel to the central axis of the magnetic body has a shape that forms a constant gap with respect to the end track when the movable portion rotates. It is preferable.

  Alternatively, the optical scanner of the present invention is an extension of a shape that forms a fixed gap on the inner surface parallel to the central axis of the magnetic body body with respect to the end orbit when the movable part rotates. A magnetic body is preferably provided.

  According to each of the above configurations, since the gap between the movable part and the fixed part is constant, it is possible to efficiently generate the magnetic flux in the direction from the permanent magnet to the magnetic pole via the magnetic column and the movable part sequentially. It becomes possible. Therefore, it is possible to prevent a reduction in torque and ensure a large deflection angle.

  In the optical scanner of the present invention, it is preferable that an inner surface parallel to the central axis of the magnetic body has a stepped shape so as to descend inward.

  According to the above configuration, when the movable portion rotates stepwise by changing the strength of the magnetic flux stepwise as in the second magnetic flux, the movable portion is stably settled in each step. Is possible.

  As described above, in the optical scanner of the present invention, the movable part has a configuration that rotates together with the reflecting surface by a biaxial gimbal mechanism, and the fixed part has a steady magnetic flux generated by a permanent magnet and a current in the coil. The driving magnetic flux for generating the electromagnetic torque for rotating the movable part on one axis is combined with the driving magnetic flux generated by flowing the electromagnetic wave to rotate the movable part. The drive magnetic flux that generates the electromagnetic torque that rotates the movable portion about the other axis is generated by applying an alternating voltage having a frequency that matches the resonance frequency of the coil to the coil. It is the structure which has arisen by being given to.

  In the optical scanner of the present invention, the movable portion has a first rotation axis that is rotated by a torsion bar and a second rotation axis that is orthogonal to the first rotation axis and rotated by another torsion bar on the same plane. A magnetic plate rotated by a gimbal mechanism and formed to include an orthogonal point between the first rotation axis and the second rotation axis, and the reflection surface provided on the magnetic plate, The center of gravity is configured such that the fixed portion has the orthogonal point located on its center axis, the first rotation axis located on a first plane including the center axis, and the center. A magnetic column that rotatably supports the movable part such that the second rotation axis is located on a second plane that includes an axis and is orthogonal to the first plane, and the reflection surface is exposed upward; The surface of the magnetic column opposite to the side supporting the movable part A fixed permanent magnet, and a U-shaped cross-sectional shape having an open upper side symmetrical with respect to the central axis in the first plane, and an upper side symmetrical with respect to the central axis in the second plane. A magnetic body having an open U-shaped cross-sectional shape and having the permanent magnet fixed so that the magnetic column is positioned on the upper side; and a current flows, whereby the first of the magnetic body. A first coil wound around the magnetic body and a current flow so as to generate a first magnetic flux passing through a portion having a planar cross-sectional shape, and thereby the cross-sectional shape of the second plane of the magnetic body is changed. A second coil wound around the magnetic body so as to generate a second magnetic flux passing through the portion formed, and the first coil is given an AC voltage having a frequency in accordance with the resonance frequency of the movable part. The second coil It is configured such that a DC voltage which changes stepwise is provided.

  Therefore, when the movable part rotates in two dimensions at a large angle, the reflecting surface can also rotate in two dimensions at a large angle. Further, as compared with a conventional polygon mirror type two-dimensional optical scanner, since a motor is not used, the size can be reduced. Therefore, it is possible to obtain a two-dimensional large deflection angle by realizing miniaturization and generating two-dimensional high torque.

  An embodiment of the present invention will be described below with reference to the drawings.

(Configuration of two-dimensional electromagnetic resonance type optical scanner)
FIG. 1 is a perspective view showing a configuration example of a two-dimensional electromagnetic resonance type optical scanner 1 according to the present embodiment. 2A is a perspective view showing the configuration of the fixed portion 10 and FIG. 2B is a perspective view showing the configuration of the movable portion 30 in the two-dimensional electromagnetic resonance type optical scanner 1 shown in FIG.

  As shown in FIG. 1 and FIG. 2, a two-dimensional electromagnetic resonance type optical scanner 1 (hereinafter abbreviated as “optical scanner 1”) of the present embodiment is a fixed unit 10 and a movable unit that operates while being supported by the fixed unit 10. Part 30. The optical scanner 1 is configured around the central axis of the magnetic column 21 of the fixed portion 10.

  As shown in FIG. 2A, the fixed portion 10 includes a core 11, four coils 12 to 15, extended magnetic poles 16 and 17, nonmagnetic materials 18 and 19, permanent magnets 20, and magnetic support columns 21. ing.

  The core 11 is a polyhedron (fixed iron core) made of a magnetic material (SUY). The core 11 is a polyhedron having a cross shape when viewed from above, and has a shape in which four end portions are bent at a right angle in the upward direction. In other words, the core 11 has a U-shaped cross-sectional shape in which an upper side symmetrical with respect to the central axis is open on the first plane including the central axis, and includes the central axis and is orthogonal to the first plane. In two planes, it has a U-shaped cross-sectional shape with an open upper side that is symmetrical with respect to the central axis.

  Here, one direction forming a cross shape in a top view is an x direction as the entire optical scanner 1, and the other direction (a direction orthogonal to the x direction) is a y direction. Further, the direction orthogonal to the xy plane is defined as the z direction. Furthermore, a direction in which a portion parallel to the z direction of the core 11 rises in the z direction is an upper side of the optical scanner 1 as a whole.

  Four coils 12 to 15 (for example, 100T each) are wound around four portions of the core 11 forming a cross shape in a top view. In addition, a member (not shown) capable of applying a voltage is connected to the coils 12 to 15 so that a current flows through the coils 12 to 15.

  The four portions of the core 11 that stand up parallel to the z direction have the same height. Then, the height of one of the opposed objects is lower than the height of the other opposed object. In FIG. 2A, the position of the upper surface of the portion facing along the x direction is lower than the position of the upper surface of the portion facing along the y direction.

  Two portions of the core 11 that face each other in the y direction, that is, two portions whose upper surface is higher, have inner side surfaces parallel to the central axis of the tip portion formed in a spherical concave shape. The detailed size of the spherical concave shape is determined so as to form a constant gap (gap) with respect to the end track when the movable portion 30 rotates based on the x-axis, as will be described later.

  The two portions of the core 11 facing in the x direction, that is, the two portions having lower upper surface positions, are provided with extended magnetic poles 16 and 17 at the tip portions, respectively, and non-magnetic materials 18 and 19 respectively. Is provided.

  The extended magnetic poles 16 and 17 are made of the same material as that of the core 11 and are formed in a shape extending from the tip and extending in the x direction so as to be integrated with the lower upper surface. In the end portions of the extended magnetic poles 16 and 17 that are located on the inner side and are not fixed, the inner side surface is formed in a spherical concave shape. The detailed size of the spherical concave shape is determined so as to form a constant gap (gap) with respect to the end track when the movable portion 30 rotates based on the y-axis, as will be described later.

  The nonmagnetic materials 18 and 19 have a prismatic shape having a predetermined height with the lower upper surface as a bottom surface. The height of the non-magnetic bodies 18 and 19 needs to be high enough to secure a gap having a sufficient magnetic resistance so that the magnetic flux does not flow through the fixed portion 10. Or the torsion bars 35 and 36 of the movable part 30 mentioned later are made into a nonmagnetic material.

  The permanent magnet 20 has a cylindrical shape, and is provided on the portion of the core 11 where the cross shape intersects in a top view so as to be concentric with the central axis. The permanent magnet 20 is provided at the center of the fixed portion 10 so that the south pole is located on the lower side and the north pole is located on the upper side, and is magnetized in the z-axis direction (for example, residual magnetic flux density 1.4T).

  The magnetic column 21 has a cylindrical shape with a conical tip. The magnetic column 21 is provided on the permanent magnet 20 so that the pointed end is located on the upper side. The movable portion 30 is rotatably supported by the tip.

  As shown in FIG. 2 (b), the movable portion 30 includes an outer magnetic body 31, an inner magnetic body 32, and four torsion bars 33 to 36. In the movable portion 30, a mirror is provided on the central portion of the inner magnetic body 32, but the illustration is omitted. The mirror may have a shape that can be accommodated in the surface region of the inner magnetic body 32.

  The outer magnetic body 31 has a hollow rectangular shape when viewed from above. And the torsion bars 35 and 36 are provided on both outer side surfaces in the longitudinal direction.

  The inner magnetic body 32 has a rectangular shape when viewed from above. And torsion bars 33 and 34 are provided on both side surfaces in the longitudinal direction, respectively. The torsion bars 33 and 34 have one end connected to the inner magnetic body 32 and the other end connected to both inner side surfaces of the outer magnetic body 31 in the short direction. That is, the first rotating shaft rotated by the torsion bars 35 and 36 and the second rotating shaft rotated by the torsion bars 33 and 34 are orthogonal to each other on the same plane.

  The outer magnetic body 31, the inner magnetic body 32, and the torsion bars 33 and 34 located inside are made of a magnetic material (SUY). The torsion bars 35 and 36 located outside are non-magnetic materials.

  Thus, in the movable part 30, the outer magnetic body 31, the torsion bars 33, 34 and the inner magnetic body 32 are rotated by the torsion bars 35, 36, and the torsion bars 33, 34 are inside the outer magnetic body 31. Thus, the inner magnetic body 32 is configured to rotate. Therefore, the movable part 30 has a configuration that is rotated by a biaxial gimbal mechanism so as to be a planar leaf spring. In addition, the movable unit 30 is configured such that the center of gravity is located at an orthogonal point between the first rotating shaft and the second rotating shaft.

  As shown in FIG. 1, the fixed unit 10 and the movable unit 30 having the above-described configuration are supported by the fixed unit 10 with the center of the inner magnetic body 32 being applied to the tip of the magnetic column 21. . That is, it is supported so that the orthogonal point is located on the central axis of the magnetic support 21. At this time, the first rotation axis by the torsion bars 35 and 36 is located on the first plane, the second rotation axis by the torsion bars 33 and 34 is located on the second plane, and the mirror is exposed to the upper side. is doing.

  Furthermore, when the movable part 30 is placed on the fixed part 10, the torsion bars 35 and 36 are in contact with the nonmagnetic materials 18 and 19. On the other hand, the end portion of the outer magnetic body 31 does not contact the core 11, and the end portion of the inner magnetic body 32 does not contact the extended magnetic poles 16 and 17.

Here, an example of each width in the optical scanner 1 will be described below.
Height from the lower surface of the core 11 to the upper surface of the nonmagnetic material 18: 11 mm
The width of the outermost shape of the two parts having the higher upper surface position in the core 11: 29 mm
The width of the outermost shape of the two parts having the lower upper surface position in the core 11: 33 mm
Movable part 30 thickness: 0.2 mm
Length in the longitudinal direction of the outer magnetic body 31: 23 mm
The length of the inner magnetic body 32 in the longitudinal direction: 6.6 mm.

(Operation principle of two-dimensional electromagnetic resonance type optical scanner)
Next, the operation principle of the optical scanner 1 having the above configuration will be described. The optical scanner 1 is roughly divided into an operation around the x-axis and an operation around the y-axis, and is driven by applying a voltage to the coils 12 to 15.

  FIG. 3 shows a cross section of the optical scanner 1 shown in FIG. 1, and is a view for explaining the driving principle around the x-axis.

  In a stopped state where no voltage is applied to the coils 12 and 13, as shown in FIG. 2A, the permanent magnet 20 forms magnetic poles A to D at the tip of the core 11. Thereby, as indicated by a solid line in FIG. 3, the magnetic flux (steady magnetic flux) generated by the permanent magnet 20 is symmetric with respect to the central axis and is generated in different directions. Specifically, one of the magnetic fluxes from the N pole of the permanent magnet 20, the magnetic column 21, the movable portion 30 (specifically, the inner magnetic body 32, the torsion bar 34, and the outer magnetic body 31), and the coil 12 Is generated in a direction toward the south pole of the permanent magnet 20 through the core 11 on the side where the magnets are provided. The other magnetic flux is provided from the N pole of the permanent magnet 20 to the magnetic column 21, the movable portion 30 (specifically, the inner magnetic body 32, the torsion bar 33, and the outer magnetic body 31), and the coil 13. It is generated in a direction toward the south pole of the permanent magnet 20 via the core 11 on the side of the permanent magnet. Therefore, the magnetic flux flows evenly on the left and right, and the balance is maintained.

  Subsequently, an AC voltage (sinusoidal AC voltage) is applied to the coils 12 and 13, and an AC current is passed through the coils 12 and 13 in the direction shown in FIG. In this driving state, as indicated by broken lines, magnetic flux (driving magnetic flux, second magnetic flux) is generated by the current flowing through the coils 12 and 13. Specifically, from the core 11 on which the coil 12 is provided, the movable portion 30 (specifically, the outer magnetic body 31, the torsion bar 34, the inner magnetic body 32, the torsion bar 33, and the outer magnetic body 31) is moved. Via, a magnetic flux is generated in a direction toward the core 11 on the side where the coil 13 is provided.

  Therefore, the magnetic flux is synthesized and strengthened on the core 11 side (the right side in the drawing) on which the coil 13 is provided. On the other hand, on the side of the core 11 on the side where the coil 12 is provided (left side in the figure), the magnetic flux cancels out and is weakened. Therefore, the suction force between the movable part 30 and the fixed part 10 increases on the one hand and decreases on the other hand. As a result, the left and right balance is lost, electromagnetic torque is generated, and the movable portion 30 rotates to the side where the coil 13 is provided.

  Further, when the alternating current is reversed, the magnetic flux is generated in the opposite direction, so that the movable portion 30 rotates in the opposite direction, that is, the side where the coil 12 is provided. In this way, by passing an alternating current through the coils 12 and 13, the movable portion 30 repeats the torsional motion using the first rotating shaft composed of the torsion bars 35 and 36.

  FIG. 4 shows a Q section of the optical scanner 1 shown in FIG. 1, and is a diagram for explaining the driving principle around the y-axis.

  In a stopped state in which no voltage is applied to the coils 14 and 15, the permanent magnet 20 generates magnetic flux (steady magnetic flux) symmetrically with respect to the central axis and generated in different directions on both sides, as indicated by the solid line. ing. Specifically, one of the magnetic fluxes from the N pole of the permanent magnet 20 to the side on which the magnetic column 21, the movable portion 30 (in detail, the inner magnetic body 32), the extended magnetic pole 16, and the coil 14 are provided. It is generated in a direction toward the south pole of the permanent magnet 20 via the core 11 in sequence. The other magnetic flux sequentially flows from the N pole of the permanent magnet 20 to the magnetic column 21, the movable part 30 (specifically, the inner magnetic body 32), the extended magnetic pole 17, and the core 11 on the side where the coil 15 is provided. It is generated in a direction toward the south pole of the permanent magnet 20 via the via. Therefore, the magnetic flux flows evenly on the left and right, and the balance is maintained.

  Subsequently, an AC voltage is applied to the coils 14 and 15, and an AC current is passed through the coils 14 and 15 in the direction as shown in FIG. In this driving state, as indicated by broken lines, magnetic flux (driving magnetic flux, first magnetic flux) is generated by the current flowing through the coils 14 and 15. Specifically, the coil 15 is provided from the core 11 on the side where the coil 14 is provided, via the extended magnetic pole 16, the movable portion 30 (specifically, the inner magnetic body 32), and the extended magnetic pole 17 in this order. A magnetic flux is generated in a direction toward the core 11 on the side where the wire is present.

  Therefore, the magnetic flux is synthesized and strengthened on the core 11 side (the right side in the figure) where the coil 15 is provided. On the other hand, on the core 11 side (left side in the figure) on the side where the coil 14 is provided, the magnetic flux cancels out and is weakened. Therefore, the suction force between the movable part 30 and the fixed part 10 increases on the one hand and decreases on the other hand. As a result, the left / right balance is lost, electromagnetic torque is generated, and the movable portion 30 rotates to the side where the coil 15 is provided.

  Further, when the alternating current is reversed, magnetic flux is generated in the opposite direction, so that the movable portion 30 rotates in the opposite direction, that is, the side where the coil 14 is provided. In this way, by passing an alternating current through the coils 14 and 15, the movable portion 30 repeats the torsional motion using the second rotating shaft composed of the torsion bars 33 and 34.

  As described above, in the optical scanner 1, the movable unit 30 rotates around the x axis and the y axis (performs a twisting motion) according to the direction of the current applied to the coils 12 to 15. Therefore, since the mirror provided in the movable part 30 also rotates, it becomes possible to rotate a mirror two-dimensionally.

  That is, by combining the magnetic flux generated by the permanent magnet 20 and the magnetic flux generated by applying a voltage to the coils 12 to 15, the magnetic flux balance in the gap portion between the core 11 and the movable portion 30 is broken, and the movable portion 30. An electromagnetic torque is generated between the leaf spring of the magnetic material and the fixed iron core as the core 11.

  Further, by setting the AC voltage applied to the coils 12 to 15 to a frequency that matches the resonance frequency of the movable part 30, it is possible to generate mechanical resonance of the movable part 30 and amplify the rotation angle.

  In addition, not only an alternating voltage but a direct voltage can also be given to the coils 12-15. When a DC voltage is applied, since the magnetic flux generated by the coil is fixed in a certain direction, it is possible to stabilize the movable unit 30 in a rotated state, that is, with a predetermined inclination. It becomes possible to control the rotation angle of the movable part 30 according to the value of the DC voltage.

(Usage example of two-dimensional electromagnetic resonance type optical scanner)
Next, a usage example corresponding to the application of the optical scanner 1 will be described. The optical scanner 1 is applied to, for example, information devices such as laser printers, various optical measuring devices, and portable projectors. In various devices, the optical scanner 1 scans a target area with light.

  In the case of two-dimensional scanning, one of the directions is often scanned at a high speed and the other direction is scanned at a low speed. For example, there is a method of scanning the target area by determining the main scanning direction and the sub-scanning direction. That is, when one line is scanned in the main scanning direction, the entire scanning is performed by repeatedly moving the sub scanning direction by one line and scanning that line in the main scanning direction. In such a method, it is desirable to rotate the mirror at high speed in the main scanning direction and to rotate the mirror at low speed or stepwise in the sub-scanning direction.

  In the optical scanner 1, rotation around the y axis is applied in the main scanning direction, and rotation around the x axis is applied in the sub scanning direction. That is, it is desirable to use rotation around the y-axis for the direction that requires high-speed rotation. This is because, when rotating around the y-axis, only the small inner magnetic body 32 rotates in the movable portion 30, and therefore, it is easy to rotate at high frequency and high speed.

  In this case, a high-frequency AC voltage that matches the resonance frequency of the movable portion 30 is applied to the coils 14 and 15, and a DC voltage that changes stepwise is applied to the coils 12 and 13. As a result, the magnetic flux generated by the coils 14 and 15 causes the movable portion 30 to repeat a high-speed torsional motion, thereby causing resonance driving. Moreover, the magnetic flux by the coils 12 and 13 rotates the movable part 30 stepwise. Therefore, the mirror can be rotated at high speed in the main scanning direction to enable high-speed scanning, and the mirror can be rotated stepwise in the sub-scanning direction.

  As described above, the optical scanner 1 is an optical scanner that scans light by reflecting incident light with the mirror of the movable unit 30 rotatably supported by the fixed unit 10. The movable part 30 has a configuration that rotates together with the mirror by a biaxial gimbal mechanism. The fixed part 10 has a configuration for generating an electromagnetic torque for rotating the movable part 30 by combining a stationary magnetic flux generated by the permanent magnet 20 and a driving magnetic flux generated by passing a current through the coils 12 to 15. Yes. A driving magnetic flux that generates an electromagnetic torque that rotates the movable part 30 about the y-axis is generated when an AC voltage having a frequency that matches the resonance frequency of the movable part 30 is applied to the coils 14 and 15. A driving magnetic flux that generates an electromagnetic torque for rotating the movable portion 30 about the x-axis is generated when a DC voltage that changes stepwise is applied to the coils 12 and 13.

More specifically,
The movable part 30 is
The first rotation axis rotated by the torsion bars 35 and 36 and the second rotation axis orthogonal to the first rotation axis and rotated by the other torsion bars 33 and 34 are rotated by the gimbal mechanism in the same plane, An inner magnetic body 32 formed to include an orthogonal point between the rotation axis and the second rotation axis;
And a mirror provided on the inner magnetic body 32.
The movable unit 30 is configured such that the center of gravity is located at the orthogonal point.
The fixing part 10 is
The orthogonal point is located on its own central axis, the first rotation axis is located on a first plane including the central axis, and the second is on a second plane including the central axis and orthogonal to the first plane. A magnetic column 21 that rotatably supports the movable portion 30 so that the rotation axis is located and the mirror is exposed on the upper side;
A permanent magnet 20 fixed to a surface opposite to the side supporting the movable portion 30 of the magnetic column 21;
The first plane has a U-shaped cross-sectional shape with an upper side opened symmetrically with respect to the central axis, and the U-shaped cross-sectional shape with an upper side opened symmetrically with respect to the central axis in the second plane. And the core 11 to which the permanent magnet 20 is fixed so that the magnetic column 21 is located on the upper side,
Coils 14 and 15 wound around the core 11 so as to generate a first magnetic flux (driving magnetic flux) that passes through a portion of the core 11 having the cross-sectional shape of the first plane when current flows;
Coils 12 and 13 wound around the core 11 are provided so as to generate a second magnetic flux (driving magnetic flux) passing through a portion of the core 11 having a cross-sectional shape of the second plane when a current flows. .
The coils 14 and 15 are supplied with an AC voltage having a frequency that matches the resonance frequency of the movable portion 30. The coils 12 and 13 are given a DC voltage that changes stepwise.

  According to the configuration of the optical scanner 1 described above, the magnetic poles C and D are formed on the core 11 at positions symmetrical to the central axis in the first plane by the permanent magnet 20 and the central axis in the second plane. Magnetic poles A and B are formed at positions symmetrical to the left and right. Thereby, in the first plane, a magnetic flux (steady magnetic flux) in a direction from the permanent magnet 20 to the magnetic poles C and D through the magnetic material column 21 and the movable portion 30 is generated symmetrically with respect to the central axis. In the second plane, magnetic flux (steady magnetic flux) in the direction from the permanent magnet 20 to the magnetic poles A and B via the magnetic material column 21 and the movable portion 30 is generated symmetrically with respect to the central axis. Therefore, the first magnetic flux and the second magnetic flux are generated in a state where the permanent magnet 20 generates a magnetic flux.

  Explaining in the first plane, the core 11 has a U-shaped cross-sectional shape with its upper side opened symmetrically with respect to the central axis, so that the first magnetic flux passes through the core 11 and the movable portion 30. Occurs. For this reason, the first magnetic flux generated by the coils 14 and 15 is weakened by canceling out the magnetic flux generated by the permanent magnet 20 on one side, and becomes stronger by being combined with the magnetic flux generated by the permanent magnet 20 on the other side. Therefore, the suction force between the movable part 30 and the fixed part 10 increases on the one hand and decreases on the other hand. Thereby, electromagnetic torque is generated and the movable part 30 rotates.

  Moreover, since the first magnetic flux is generated when an AC voltage is applied to the coils 14 and 15, the generation direction is alternately switched. Thereby, the movable part 30 repeats torsional motion. Since the frequency of the AC voltage is adjusted to the resonance frequency of the movable part 30, the movable part 30 performs resonance driving, and thus it is possible to amplify the rotation angle (deflection angle).

  Also in the second plane, the movable part 30 rotates by the same principle. Since the second magnetic flux is generated when a DC voltage that changes stepwise is applied to the coils 12 and 13, the generation direction is constant and the strength of the magnetic flux changes stepwise. Thereby, the movable part 30 rotates in steps.

  Thus, the movable part 30 rotates in two dimensions at a large angle by using the torsional resonance and electromagnetic force generated by the torsion bar of the leaf spring of the gimbal mechanism, so that the mirror also rotates in two dimensions at a large angle. It becomes possible. Further, as compared with a conventional polygon mirror type two-dimensional optical scanner, since a motor is not used, the size can be reduced. Accordingly, it is possible to obtain a large deflection angle at a high speed in two dimensions by realizing a reduction in size and generating a high torque in two dimensions.

  Further, in the optical scanner 1, the inner surface parallel to the central axis of the core 11 has a shape that forms a constant gap with respect to the end track when the movable portion 30 rotates. Further, in the optical scanner 1, the extended magnetic poles 16 and 17 are formed on the inner surface parallel to the central axis of the core 11 so as to form a fixed gap with respect to the end orbit when the movable portion 30 rotates. Is provided. Thereby, since the gap between the movable part 30 and the fixed part 10 becomes constant, the magnetic flux in the direction toward the magnetic poles A to D from the permanent magnet 20 via the magnetic column 21 and the movable part 30 sequentially, It can be generated efficiently. Therefore, it is possible to prevent a reduction in torque and ensure a large deflection angle.

  In the optical scanner 1, the inner surface parallel to the central axis of the core 11 is not limited to the shape described above, and may have, for example, a stepped shape that descends inward. According to this, when a DC voltage that changes stepwise is given and the strength of the magnetic flux changes stepwise, when the movable portion 30 rotates stepwise, the movable portion 30 is stabilized in each step. It is possible to settle down.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention is not only suitable for use in the field relating to optical scanners, but can also be suitably used in the field relating to methods for controlling optical scanners and methods for producing optical scanners. , For example, in the fields of laser printers, bar code readers, spatial area sensors, laser markers, optical VOAs, optical wireless communication devices, image displays, and optical measuring instruments such as three-dimensional shape measuring instruments and laser dimension measuring instruments Can be used widely.

1 is a perspective view showing an embodiment of a two-dimensional electromagnetic resonance type optical scanner according to the present invention. In the two-dimensional electromagnetic resonance type optical scanner, (a) is a perspective view showing a configuration of a fixed portion, and (b) is a perspective view showing a configuration of a movable portion. FIG. 2 is a diagram illustrating a P section of the two-dimensional electromagnetic resonance type optical scanner illustrated in FIG. 1 and illustrating a driving principle around an x axis. FIG. 2 is a diagram illustrating a Q section of the two-dimensional electromagnetic resonance type optical scanner illustrated in FIG. 1 and is a diagram for explaining a driving principle around a y-axis. It is a figure which shows the structure of the conventional polygon mirror type two-dimensional scanning optical scanner. It is a figure which shows the structure of the conventional MEMS type two-dimensional scanning optical scanner.

Explanation of symbols

1 Two-dimensional electromagnetic resonance type optical scanner (optical scanner)
10 Fixed part 11 Core (magnetic body)
12, 13 coil (second coil)
14, 15 coil (first coil)
16, 17 Extended magnetic pole (extended magnetic body)
18, 19 Non-magnetic material 20 Permanent magnet 21 Magnetic material support 30 Movable part 31 Outer magnetic material 32 Inner magnetic material (magnetic plate)
33, 34 Torsion bar 35, 36 Torsion bar

Claims (5)

In an optical scanner that scans light by reflecting incident light on a reflecting surface of a movable part that is rotatably supported by a fixed part,
The movable part has a configuration that rotates together with the reflecting surface by a biaxial gimbal mechanism,
The fixed portion has a configuration for generating an electromagnetic torque for rotating the movable portion by combining a stationary magnetic flux generated by a permanent magnet and a driving magnetic flux generated by passing a current through a coil.
A driving magnetic flux for generating an electromagnetic torque for rotating the movable part on one axis is generated by applying an AC voltage having a frequency in accordance with a resonance frequency of the movable part to the coil,
An optical scanner characterized in that a driving magnetic flux for generating an electromagnetic torque for rotating the movable portion on the other shaft is generated by applying a DC voltage that changes stepwise to the coil. In an optical scanner that scans light by reflecting incident light on a reflecting surface of a movable part that is rotatably supported by a fixed part,
The movable part is
A first rotation axis rotated by a torsion bar and a second rotation axis orthogonal to the first rotation axis and rotated by another torsion bar are rotated by a gimbal mechanism on the same plane, and the first rotation axis and the A magnetic plate formed so as to include a point perpendicular to the second rotation axis;
And the reflection surface provided on the magnetic plate, and is configured such that the center of gravity is located at the orthogonal point,
The fixed part is
The orthogonal point is located on its own central axis, the first rotational axis is located on a first plane including the central axis, and on a second plane including the central axis and orthogonal to the first plane. A magnetic column that rotatably supports the movable part such that the second rotating shaft is located and the reflective surface is exposed upward;
A permanent magnet fixed to a surface opposite to the side supporting the movable part of the magnetic column;
The first plane has a U-shaped cross-sectional shape that is open on the upper side that is symmetrical with respect to the central axis, and the upper surface that is symmetrical with respect to the central axis on the second plane. A magnetic body having a cross-sectional shape and having the permanent magnet fixed so that the magnetic column is positioned on the upper side;
A first coil wound around the magnetic body so as to generate a first magnetic flux that passes through a portion of the magnetic body that forms the cross-sectional shape of the first plane when an electric current flows;
A second coil wound around the magnetic body so as to generate a second magnetic flux that passes through a portion of the magnetic body that forms the cross-sectional shape of the second plane when an electric current flows;
An optical scanner, wherein an AC voltage having a frequency matched to a resonance frequency of the movable part is applied to the first coil, and a DC voltage that changes stepwise is applied to the second coil.   An inner surface parallel to the central axis of the magnetic body has a shape that forms a certain gap with respect to an end track when the movable portion rotates. Item 3. The optical scanner according to Item 2.   An extended magnetic body having a shape that forms a certain gap with respect to the end orbit when the movable portion rotates is provided on the inner surface parallel to the central axis of the magnetic body. The optical scanner according to claim 2.   The optical scanner according to claim 2, wherein an inner surface parallel to the central axis of the magnetic body has a stepped shape that descends inward.

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