JP2007333872A - Beam scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a beam scanner which is operated at a high speed. <P>SOLUTION: The beam scanner has: a supporting member; a rotation shaft supported by the supporting member; a yoke which is arranged facing to the circumferential direction of the side face of the rotation shaft, fixed on the supporting member, projected from the plane facing to the side face of the rotation shaft toward the rotation shaft, defining the gap with the rotation shaft, and includes a plurality of magnetic poles arranged in the rotating direction of the rotation shaft; a reflection mirror fixed on the rotation shaft; a pair of permanent magnets fixed in the rotating direction on the side face of the yoke side when the rotation shaft is stationary at a neutral position, and magnetized in the radial direction of the rotation shaft; and coils wound on the magnetic poles, wherein the magnetic poles are arranged symmetrically with respect to a neutral plane including a virtual straight line which is the rotation center of the rotation shaft, the pair of the permanent magnets have a geometrical shape symmetrical with respect to the neutral plane when the rotation shaft is stationary at the neutral position and have reversed polarities, and the coils are wound so that the end parts on the rotation shaft side of the magnetic poles arranged symmetrically with respect to the neutral plane may be magnetized in the same polarity. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a beam scanner including a mirror capable of reflecting and scanning an incident beam.

  When processing is performed by irradiating a laser beam, high-speed processing is possible by using a galvano scanner (beam scanner) that reflects and scans the beam with a galvano mirror (rotating mirror). Become.

  FIG. 4 is a schematic view of a laser processing apparatus including a galvano scanner. The laser processing apparatus includes a laser oscillator 12, a first galvano scanner 20, a second galvano scanner 24, an fθ lens 6, and a stage 8. The first and second galvano scanners 20 and 24 include rotating mirrors 20a and 24a, respectively. As shown in the figure, when the XYZ rectangular coordinate system is defined, the rotary mirror 20a of the first galvano scanner 20 rotates around an axis parallel to the Z axis, for example, and the rotary mirror 24a of the second galvano scanner 24 Rotate around an axis parallel to the axis.

  The laser oscillator 12 emits a pulse laser beam 14 in a direction parallel to the XY plane, for example. The emitted pulse laser beam 14 is reflected by the rotary mirror 20a of the first galvano scanner 20 in a predetermined direction parallel to the XY plane. The pulse laser beam 14 is further reflected in a predetermined direction by the rotating mirror 24 a of the second galvano scanner 24, passes through the fθ lens 6, and irradiates the workpiece 10 placed on the stage 8. The pulse laser beam 14 is deflected by the fθ lens 6 in a direction perpendicular to the surface of the workpiece 10 and is incident on the workpiece 10.

  The laser beam 14 scans the workpiece 10 by rotating the rotating mirrors 20a, 24a of the first and second galvano scanners 20, 24 and changing the traveling direction of the laser beam 14.

  FIG. 5 is a cross-sectional view schematically showing the moving coil galvano scanner. The galvano scanner has a rotating mirror 33 that reflects incident light, a rotating shaft 30 that holds the rotating mirror 33 at the tip and rotates around it, first and second bearings 31 and 32 that rotatably support the rotating shaft 30, and rotation. A coil 34 fixed to the shaft 30, a permanent magnet 35 and a yoke 36 for rotating the rotating mirror 33 by applying a driving force to the coil 34, and an angle sensor 37 for detecting the rotation angle of the rotating mirror 33 are included. Composed.

  When a current is passed through the coil 34 disposed in the magnetic field created by the permanent magnet 35 and the yoke 36, rotational torque is generated. The generated torque is transmitted to the rotating shaft 30 supported by the first and second bearings 31 and 32 to rotate the rotating mirror 33. The rotation angle of the rotary mirror 33 is measured by an angle sensor 42 attached to the end of the rotary shaft 30 opposite to the rotary mirror 33.

  There is an increasing demand for high-speed, high-precision driving of galvano scanners. However, in the galvano scanner shown in FIG. 5, since the rotary mirror 33, the coil 34, and the angle sensor 37 are arranged in series with the rotary shaft 30, resonance due to torsional deformation of the rotary shaft 30 is likely to occur. In particular, the rotating mirror 33 and the angle sensor 37 attached to both ends of the rotating shaft 30 are the main causes of the resonance phenomenon due to the torsional deformation of the rotating shaft 30 and hinder the high-speed driving of the rotating mirror 33.

  Further, when torsional deformation occurs on the rotating shaft 30, there is a case where a deviation occurs between the actual rotation angle of the rotating mirror 33 and the measured value by the angle sensor 37, and the positioning accuracy of the laser irradiation position may be lowered.

  In order to solve such problems, a configuration in which a rotating mirror is not arranged in series at the end of the rotating shaft has been proposed (see, for example, Patent Documents 1, 2, and 3). Patent Document 1 discloses a galvanomirror device having a configuration in which a coil is directly attached to the back surface of a mirror. Patent Documents 2 and 3 disclose configurations in which coils are arranged at both ends of a mirror (mirror type optical path deflecting device and scanner device, respectively).

  These configurations are effective when a mechanism for rotating a small mirror is constructed in a compact manner. However, when the mirror is large, it is not easy to generate a torque sufficient for driving, and it is not suitable for high-speed and high-precision driving.

  In particular, in the configuration in which the coil is directly attached to the mirror, heat generated by the coil is easily transmitted to the mirror, and as a result, the cross-sectional shape and positioning accuracy of the laser beam reflected by the mirror may be deteriorated. For this reason, there is a problem that a current sufficient for high-speed driving cannot be supplied. Furthermore, since the heat generated in the coil reduces the rigidity of the coil, resonance is likely to occur in the movable part, making it difficult to achieve high speed and high accuracy.

  The moving coil galvano scanner has a configuration in which a coil is disposed on a rotor and a permanent magnet is disposed on a stator. On the other hand, a moving magnet type galvano scanner having a configuration in which a permanent magnet is disposed on a rotor and a coil is disposed on a stator is also known (see, for example, Patent Document 4).

  The galvano scanner (galvano mirror actuator) described in Patent Document 4 has a configuration in which a permanent magnet is disposed on the back surface of a mirror frame that holds a mirror. According to this configuration, conduction of heat generated in the coil to the mirror can be prevented. However, when the mirror is large, it is not easy to generate a torque sufficient for driving.

  A large torque can be obtained by increasing the number of turns of the coil. However, in this case, the coil gap also becomes thick, the permeance coefficient becomes small, and demagnetization occurs in the permanent magnet. In addition, the amount of heat generated in the coil increases. For this reason, increasing the number of turns of the coil cannot be said to meet the demand for high speed and high precision driving.

Japanese Patent Laid-Open No. 7-104207 JP-A-6-331909 JP 2003-43405 A JP 2000-81588 A

  An object of the present invention is to provide a beam scanner capable of operating at high speed.

  Another object of the present invention is to provide a beam scanner capable of operating with high accuracy.

  According to one aspect of the present invention, the support member, the rotation shaft rotatably supported by the support member, and the side surface of the rotation shaft are disposed so as to face a part of the region in the circumferential direction, A yoke fixed to the support member, protrudes from the surface facing the side surface of the rotary shaft toward the rotary shaft, defines a gap between the side surface of the rotary shaft, and the rotational direction of the rotary shaft A yoke including a plurality of magnetic poles arranged so as to be aligned with each other, a reflecting mirror fixed to the rotating shaft, and fixed to a side surface facing the yoke when the rotating shaft is stationary in a neutral position with respect to the rotation direction And a pair of permanent magnets arranged in the rotational direction and magnetized in the radial direction of the rotating shaft, and a coil wound around the magnetic pole, the magnetic pole having a rotational center of the rotating shaft A symmetric relationship with respect to the neutral plane containing the virtual line The pair of permanent magnets has a geometrical shape that is symmetrical with respect to the neutral plane when the rotating shaft is stationary at the neutral position, and the polarities are mutually different. A beam scanner is provided in which the coil is wound so that the end on the rotating shaft side of the magnetic pole arranged at a symmetrical position with respect to the neutral plane is excited to the same polarity.

  This beam scanner is a beam scanner having high speed and high accuracy in operation.

  According to the present invention, it is possible to provide a beam scanner capable of operating at high speed.

  Further, it is possible to provide a beam scanner that can operate with high accuracy.

  1A to 1C are schematic cross-sectional views showing a galvano scanner according to the first embodiment.

  Reference is made to FIG. The galvano scanner according to the first embodiment is made of a magnetic material, and a swing axis C penetrating the inside in the length direction is defined. A shaft 52 that can rotate (rotate) around the swing axis C, A power source (a driving torque for rotating the shaft 52 together with the flat mirror 51 that is attached to the upper portion in the radial direction (light incident side), reflects the incident light, the permanent magnet 53 that is fixed to the lower portion in the radial direction of the shaft 52, and the permanent magnet 53. A salient pole yoke 62 and a coil 61 made of a magnetic material, which constitute a torque generation source). The mirror 51 is disposed on the opposite side of the salient pole yoke 62 with respect to the shaft 52.

  The coil 61 is disposed on the salient pole type yoke 62, and the salient pole type yoke 62 is fixed to the fixed base 65. The fixed base 65 defines a fixed reference position of the galvano scanner according to the embodiment.

  The shaft 52 oscillates (rotates) around the oscillating axis C at two points separated along the length direction by bearing holders 64a and 64b fixed to the fixed base 65 via the bearings 54a and 54b. It is supported freely.

  A stopper 55 is attached to one end of the shaft 52 in the length direction. The rotation range of the shaft 52 can be limited by the stopper 55 and the stopper holder 63 fixed to the bearing holder 64a.

  The galvano scanner also includes an angle sensor 42. The angle sensor 42 is indirectly fixed to the scale 42a fixed to the end of the shaft 52 opposite to the end to which the stopper 55 is attached, and to the fixed base 65 (position with respect to the fixed base 65). The encoder head 42b is included. An origin position is defined on the scale 42a. The encoder head 42b can detect the rotational position of the mirror 51 by reading the displacement of the origin position accompanying the swing of the scale 42a.

  FIG. 1B is a cross-sectional view taken along line 1B-1B in FIG.

  The vicinity of the center in the length direction of the shaft 52 has a shape in which, for example, a part of a cylinder is cut along the central axis (oscillation axis C) so that the cut surface becomes a plane. Therefore, the cross section of the shaft 52 at this position has a shape obtained by cutting a part of an arc from a circle into a chord shape. The mirror 51 is directly fixed on the cut plane portion of the shaft 52.

  Permanent magnets 53a and 53b having the same shape and the same characteristics are fixed to the cylindrical side surface of the shaft 52 opposite to the side where the mirror 51 is disposed. The permanent magnets 53 a and 53 b are a pair of permanent magnets that are arranged in the rotational direction of the shaft 52 and magnetized in the radial direction of the shaft 52.

  In the permanent magnets 53a and 53b, the S pole and the N pole are arranged in opposite directions. For example, the permanent magnet 53a is arranged with the S pole on the shaft 52 side and the N pole on the salient pole yoke 62 side, and the permanent magnet 53b has the N pole on the shaft 52 side and the S pole on the salient pole yoke 62 side. Placed.

  Further, the permanent magnets 53a and 53b are formed in parallel to the central axis (swing axis C) of the shaft 52. Further, a virtual plane P that includes the central axis (oscillation axis C) of the shaft 52 and intersects the plane mirror 51 perpendicularly (the virtual plane P is fixed to the shaft 52 and swings around the oscillation axis C together with the shaft 52. Is a moving virtual plane). The plane mirror 51 and the shaft 52 are also self-symmetric with respect to the virtual plane P.

  As shown, an XYZ coordinate system is defined. When the vertical direction is the Z direction and the fixed base 65 is disposed in a plane parallel to the XY plane, the shaft 52 is disposed such that the central axis (swing axis C) is parallel to the Y direction.

  The salient pole yoke 62 is disposed so as to face a part of the side surface of the shaft 52 in the circumferential direction. The salient pole-shaped yoke 62 is formed with a semi-cylindrical hollow having, for example, a swing axis C as a central axis, and a shaft 52 side (permanent magnet) is formed on the hollow surface (a surface facing the side surface of the shaft 52). 53a and 53b side), slots 66a to d which are convex portions protruding vertically are formed. For example, the slots 66a to 66d have the same shape. The slots 66a to 66d are arranged so as to define a gap with the side surface of the shaft 52 and to be aligned in the rotation direction of the shaft 52.

  The slots 66a to 66d are formed at regular intervals, for example, parallel to the Y axis, that is, parallel to the swing axis C. Further, they are arranged so as to have a symmetrical relationship with respect to a plane including the swing axis C and parallel to the YZ plane (neutral plane, a plane that coincides with the virtual plane P in FIG. 1B). The slot 66a and the slot 66d are formed at symmetrical positions, and the slot 66b and the slot 66c are formed at symmetrical positions.

  Coils 61a to 61d are wound around the slots 66a to 66d, respectively.

  As described above, in the galvano scanner according to the embodiment, the mirror 51 is directly fixed to the shaft 52. When the mirror 51 is attached to the shaft 52, for example, a mirror frame that holds the mirror 51 is not used, so that the rigidity can be increased. Thereby, resonance due to bending deformation of the mirror 51 and resonance due to torsional deformation of the shaft 52 can be suppressed, and the mirror 51 can be positioned with high speed and high accuracy.

  The coils 61a to 61d are disposed in the yoke 62 (slots 66a to 66d) and are not disposed on the shaft 52 side. Therefore, it is possible to prevent deterioration of the shape and positioning accuracy of the laser beam (laser beam reflected by the mirror 51) generated by the heat generated in the coils 61a to 61d being conducted to the mirror 51.

  The structure and operation of the power source will be described with reference to FIG. This figure shows a state where the shaft 52 is stationary with respect to the rotation direction at an equilibrium position (neutral position) when the coil is not energized and the magnetic force of the permanent magnets 53a and 53b is not taken into consideration.

  The slots 66a to 66d of the salient pole yoke 62 stand up vertically toward the central axis (oscillation axis C) of the shaft 52. For this reason, the center line of each of the slots 66a to 66d extends toward the swing axis C.

  The permanent magnets 53a and 53b are fixed to the side surface of the shaft 52 facing the salient pole yoke 62 side, and have a geometric shape that is symmetrical with respect to the neutral plane.

  The permanent magnets 53a and 53b are disposed between two slots adjacent to each other in the rotation direction of the shaft 52. In the first embodiment, the permanent magnet 53a is disposed between the center line of the slot 66a and the center line of the slot 66b, and the permanent magnet 53b includes the center line of the slot 66c and the center line of the slot 66d. It is arranged between. Both of the cross-sectional shapes of the permanent magnets 53a and 53b are shapes obtained by removing the shaft 52 from the fan shape centered on the swing axis C.

  In the slots 66a to 66d, coils 61a to 61d are formed with the same number of turns, respectively, by a single continuous wire. The coil is wound so that the ends of the slots 52 (slots 66a and 66d, slots 66b and 66c) arranged at symmetrical positions with respect to the neutral plane are excited with the same polarity. . The winding direction of the coil 61a and the coil 61d is equal, and the winding direction of the coil 61b and the coil 61c is equal. For this reason, when current flows in one direction, magnetic poles in the same direction are formed in the slots 66a and 66d. In addition, when current flows in one direction, magnetic poles in the same direction are formed in the slots 66b and 66c. The direction of the magnetic poles of the slots 66a and 66d is opposite to the direction of the magnetic poles of the slots 66b and 66c.

  For example, when a current is passed along the arrow of “current direction” in the figure, an N pole is formed in the center (swing axis C) direction for the slots 66a and 66d, and the center (swinging) for the slots 66b and 66c. The south pole is formed in the direction of the moving axis C).

  In this figure, the lines of magnetic force formed in the galvano scanner are shown with an arrow on the closed curve. A magnetic circuit is formed in the direction of the permanent magnet 53a, the slot 66b (coil 61b), the salient pole yoke 62, the slot 66d (coil 61d), the permanent magnet 53b, the shaft 52, and the permanent magnet 53a.

  In the state where the magnetic poles are formed as shown, a repulsive force acts between the permanent magnet 53a and the slot 66a, and an attractive force acts between the permanent magnet 53a and the slot 66b. Further, a repulsive force acts between the permanent magnet 53b and the slot 66c, and an attractive force acts between the permanent magnet 53b and the slot 66d.

  Rotational torque (in the case shown in the figure) that swings the movable part (the shaft 52, the mirror 51, the permanent magnets 53a, 53b, and the scale 42a) around the swing axis C by these attractive force and repulsive force. Counterclockwise direction).

  In the galvano scanner according to the first embodiment, the permanent magnets 53a and 53b are arranged with the south pole and the north pole opposite to each other, but both the same magnetic poles are directed in the radial direction toward the salient pole yoke 62. May be. In this case, the coils 61a to 61d are arranged so that the same direction magnetic pole is generated in the slot 66a and the slot 66c, and the same direction magnetic pole in the opposite direction is generated in the slot 66b and the slot 66d.

  FIG. 2 is a schematic sectional view showing the vicinity of the power source of the galvano scanner according to the second embodiment, and corresponds to FIG. The galvano scanner according to the second embodiment differs from the galvano scanner according to the first embodiment in the configuration of the power source. This figure shows a state where the shaft 52 is stationary with respect to the rotation direction at an equilibrium position (neutral position) when the coil is not energized and the magnetic force of the permanent magnets 53a and 53b is not taken into consideration.

  In the second embodiment, the salient pole yoke 62 is formed with three slots 66a to 66c. The slot 66a and the slot 66c are formed at symmetrical positions with respect to the neutral plane (a plane that coincides with the virtual plane P in FIG. 2). The slot 66b is formed so that the center line is in the neutral plane. Thus, the galvano scanner according to the second embodiment is the first implementation in that one of the slots is arranged on the neutral plane and the slot has a symmetrical geometry with respect to the neutral plane. Different from the example. Coils 61a to 61c are disposed in the slots 66a to 66c, respectively.

  Permanent magnets 53a and 53b are arranged with the south and north poles in opposite directions. For example, the permanent magnet 53a is arranged with the S pole on the shaft 52 side and the N pole on the salient pole yoke 62 side, and the permanent magnet 53b has the N pole on the shaft 52 side and the S pole on the salient pole yoke 62 side. Placed. The permanent magnet 53a is disposed between the center line of the slot 66a and the center line of the slot 66b, and the permanent magnet 53b is disposed between the center line of the slot 66b and the center line of the slot 66c. .

  Coils 61a to 61c are formed in the slots 66a to 66c by a single continuous wire. The winding direction of the coil 61a and the coil 61c is equal, and the winding direction of the coil 61b is opposite to that. Moreover, the number of turns of the coil 61a and the coil 61c is equal, and is ½ of the number of turns of the coil 61b.

  For this reason, when current flows in one direction, magnetic poles in the same direction are formed in the slots 66a and 66c, and magnetic poles in the opposite direction are formed in the slots 66b.

  For example, when a current is passed along the arrow of “current direction” in the figure, an N pole is formed in the center (oscillation axis C) direction for the slots 66a and 66c, and the center (oscillation axis) for the slot 66b. C) A south pole is formed in the direction.

  The lines of magnetic force formed in the galvano scanner are shown with an arrow on the closed curve. A magnetic circuit is formed in the direction of the permanent magnet 53a, the slot 66b (coil 61b), the salient pole yoke 62, the slot 66c (coil 61c), the permanent magnet 53b, the shaft 52, and the permanent magnet 53a.

  In the state where the magnetic poles are formed as shown, a repulsive force acts between the permanent magnet 53a and the slot 66a, and an attractive force acts between the permanent magnet 53a and the slot 66b. Further, a repulsive force acts between the permanent magnet 53b and the slot 66b, and an attractive force acts between the permanent magnet 53b and the slot 66c.

  By these suction force and repulsive force, a rotational torque that causes the movable portion to swing around the swing axis C is generated in the counterclockwise direction in the case shown in the figure.

  The galvano scanner according to the first and second embodiments can generate a large torque sufficient for high-speed driving of the large mirror. Further, the resonance due to the bending deformation of the mirror and the torsional deformation of the shaft can be suppressed, and the mirror can be positioned stably at high speed. Further, the amount of heat generated by the coil is small, and demagnetization of the permanent magnet is unlikely to occur. The galvano scanner according to the embodiment can realize high-speed and high-precision operation even when a large mirror is used.

  FIG. 3 is a graph showing torque characteristics of the galvano scanner according to the first and second embodiments.

  The horizontal axis of the graph shows the rotation angle from the 0 ° position in the unit “degree (°)”, and the vertical axis shows the torque with the maximum torque as the reference (100%) in the unit “%”. It was. Here, the 0 ° position means a position at which the virtual plane P coincides with the neutral plane, as shown in FIGS.

  The angle formed by the neutral plane and the virtual plane P when the movable part swings was defined as the rotation angle. In FIG. 1C and FIG. 2, when the virtual plane P is rotated counterclockwise from the 0 ° position, the rotation angle is defined as positive, and when rotated in the clockwise direction, the rotation angle is defined as negative. .

  Curve a shows the relationship between the rotation angle and generated torque for the galvano scanner according to the first embodiment, and curve b shows the relationship between the galvano scanner according to the second embodiment. The graph was created assuming that the current flowing through the coil was constant.

  For both the first and second embodiments, the generated torque decreases as the absolute value of the rotation angle increases.

  Further, it can be seen that the galvano scanner according to the first embodiment has a smaller torque fluctuation due to the rotation angle than the galvano scanner according to the second embodiment.

  As mentioned above, although this invention was demonstrated along the Example, this invention is not limited to these. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  It can be used in general for laser processing and laser processing apparatus. In particular, it is suitably used for laser processing that requires high-speed and high-accuracy beam scanning, such as laser drilling and laser marking, and an apparatus for performing such laser processing. Further, it is used in laser processing and laser processing apparatus in which a large mirror is suitably used.

(A)-(C) are schematic sectional drawings which show the galvano scanner by a 1st Example. It is a schematic sectional drawing which shows the motive power source vicinity of the galvano scanner by a 2nd Example. It is a graph which shows the torque characteristic of the galvano scanner by the 1st and 2nd Example. It is the schematic of the laser processing apparatus containing a galvano scanner. It is sectional drawing which shows the outline of a moving coil type galvano scanner.

Explanation of symbols

6 fθ lens 8 stage 10 workpiece 12 laser oscillator 14 laser beam 20 first galvano scanner 20a rotating mirror 24 second galvano scanner 24a rotating mirror 30 rotating shaft 31 first bearing 32 second bearing 33 rotating mirror 34 coil 35 permanent magnet 36 Yoke 37 Angle sensor 42 Angle sensor 42a Scale 42b Encoder head 51 Mirror 52 Shaft 53, 53a, 53b Permanent magnet 54a, 54b Bearing 55 Stopper 61, 61a-d Coil 62 Salient pole type yoke 63 Stopper holder 64a, 64b Bearing holder 65 Fixed base 66a-d Slot C Oscillating axis P Virtual plane

Claims (3)

A support member;
A rotating shaft rotatably supported by the support member;
A yoke that is disposed so as to face a part of the side surface of the rotating shaft in the circumferential direction and is fixed to the support member, from the surface facing the side surface of the rotating shaft toward the rotating shaft A yoke including a plurality of magnetic poles protruding and defining a gap with a side surface of the rotation shaft and arranged to be aligned in a rotation direction of the rotation shaft;
A reflector fixed to the rotating shaft;
A pair of permanent magnets fixed to the side facing the yoke side and arranged side by side in the rotational direction and magnetized in the radial direction of the rotational shaft when the rotational shaft is stationary at a neutral position in the rotational direction; ,
A coil wound around the magnetic pole,
The magnetic poles are arranged so as to have a symmetric relationship with respect to a neutral plane including a virtual straight line serving as a rotation center of the rotation axis,
The pair of permanent magnets have geometric shapes that are symmetrical with each other with respect to the neutral plane when the rotation shaft is stationary in a neutral position, and the polarities are opposite to each other;
The coil is a beam scanner in which the coil is wound so that the end on the rotating shaft side of the magnetic pole arranged at a symmetric position with respect to the neutral plane is excited to the same polarity.   The beam scanner according to claim 1, wherein the permanent magnet is disposed between the two magnetic poles adjacent to each other with respect to a rotation direction when the rotation shaft is stationary at a neutral position.   3. The beam scanner according to claim 1, wherein one of the magnetic poles is disposed on the neutral plane and has a symmetrical geometrical shape with respect to the neutral plane.

Images