JP2011043674A - Galvano scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a galvano scanner having capability of high-speed operation. <P>SOLUTION: The galvano scanner includes: a shaft that is rotatable around the center of rotation and that has a first position detection mark formed along the rotating direction; a galvano mirror that is fixed to the shaft to reflect an incident light beam; a rotary mechanism that rotates the shaft around the center of the rotation; a light-emitting device that makes light incident on the first position detection mark of the shaft; a light-receiving device on which light from the light-emitting device, which is reflected by the first position detection mark of the shaft, is incident; and a rotary position-deriving part that derives the position in the rotating direction of the shaft on the basis of the incident light on the light-receiving device. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a galvano scanner that deflects and emits a light beam such as a laser beam.

  FIG. 4 is a perspective view showing a conventional galvano scanner. The galvano scanner is used, for example, in a laser drill apparatus that forms a via hole in a printed board.

  The galvano scanner includes a galvano mirror 10, a mirror mount 11, a shaft 12, bearings 13 a and 13 b, a coil 14, magnets 15 a and 15 b, and an encoder unit 16. The encoder unit 16 includes a hub 17, a disk 18, a slit 19, a light emitting element 20, and a light receiving element 21.

  A galvano mirror 10 that reflects and deflects an incident light beam is fixed to a shaft 12 via a mirror mount 11. The shaft 12 is supported by a housing of the galvano scanner by two bearings 13a and 13b so as to be rotatable around its central axis (rotation center). A coil 14 is fixed to the shaft 12 between the bearings 13a and 13b. A pair of magnets 15a and 15b having different polarities are disposed so as to sandwich the coil 14. The shaft 12 can be rotated by the magnets 15a and 15b and the coil 14 disposed in the magnetic field. That is, the turning mechanism for turning the shaft 12 includes the coil 14 and the magnets 15a and 15b.

  The encoder unit 16 is a detection unit that detects information for deriving the rotational position (rotation angle) of the shaft 12, and is installed on the opposite side of the galvanometer mirror 10 with the bearings 13a and 13b interposed therebetween. The disk 18 constituting the encoder unit 16 is fixed to the shaft 12 via the hub 17 and rotates with the rotation of the shaft 12. A slit 19 is formed in the disk 18. A light emitting element 20 and a light receiving element 21 are arranged across the slit 19 formation position of the disk 18. The light emitting element 20 is, for example, a light emitting diode (LED), and the light receiving element 21 is, for example, a photodiode (Photo Diode; PD). The light emitted from the light emitting element 20 and transmitted through the slit 19 enters the light receiving element 21.

  Based on the light received by the light receiving element 21, the rotation angle of the shaft 12 is grasped. When the galvano mirror 10 is rotated, control for rotating the galvano mirror 10 to a desired angle is performed with reference to the grasped rotation angle of the shaft 12.

  FIG. 5 is a cross-sectional view showing a part of a conventional galvano scanner. As described above, the disk 18 with slits is attached to the shaft 12 by the hub 17 in order to detect the rotational position (rotation angle) of the shaft 12. In order to improve detection accuracy, the number of slits is increased for the purpose of increasing resolution. Increasing the number of slits increases the diameter of the disk 18. When the diameter of the disk 18 increases, the mass of the disk 18 and the inertia (moment of inertia) of the rotating part increase, and the high-speed operation of the galvano scanner is hindered.

  An invention of a galvano scanner that enables highly accurate rotation angle measurement even during high-speed operation of a galvano mirror without being affected by changes in humidity has been disclosed (for example, see Patent Document 1).

JP 2003-307700 A

  An object of the present invention is to provide a galvano scanner capable of high-speed operation.

  According to one aspect of the present invention, a shaft that is rotatable around a rotation center and has a first position detection mark formed in the rotation direction, and a galvano that is fixed to the shaft and reflects an incident light beam. A mirror, a rotation mechanism that rotates the shaft around the rotation center, a light emitter that causes light to enter the first position detection mark of the shaft, and the first position detection mark of the shaft. There is provided a galvano scanner having a reflected light receiver that receives light from the light emitter, and a rotational position deriving unit that derives a position of the shaft in the rotational direction based on the light incident on the light receiver. .

  According to the present invention, a galvano scanner capable of high-speed operation can be provided.

(A) is the schematic which shows the encoder part 16 of the galvano scanner by an Example, (B) And (C) is sectional drawing which shows the shaft 12 in the encoder part 16. FIG. A correspondence between an analog signal indicating the intensity of light reflected at the positions where the slits 19a and 19b are formed and detected by the light receiving elements 21a and 21b and a reflection position where the slits 19a and 19b are formed is shown. It is a block diagram which shows the operation control of the galvano scanner by an Example. It is a perspective view which shows the conventional galvano scanner. It is sectional drawing which shows a part of conventional galvanometer scanner.

  FIG. 1A is a schematic diagram illustrating an encoder unit 16 of a galvano scanner according to an embodiment. FIGS. 1B and 1C are cross-sectional views illustrating a shaft 12 in the encoder unit 16. The configuration of the galvano scanner according to the embodiment other than the encoder unit 16 is the same as that of the conventional galvano scanner shown in FIG.

  Reference is made to FIG. The encoder section 16 of the galvano scanner according to the embodiment includes, for example, two rows of slits 19a, 19b formed on the surface (cylindrical surface) of a cylindrical shaft 12 made of stainless steel (SUS) and having a diameter of 7 mm. The light emitting element 20, light receiving elements 21a and 21b, and imaging lenses 22a and 22b are included. The light emitting element 20 is, for example, an LED, and the light receiving elements 21a, 21b are, for example, photodetectors.

  The slits 19 a and 19 b are, for example, concave portions extending in the extending direction (axial direction and length direction) of the shaft 12, and both the formation row of the slit 19 a and the formation row of the slit 19 b are along the rotation direction of the shaft 12. Are arranged.

  The light emitted from the light emitting element 20 is reflected by the slit 19a, 19b formation region of the shaft 12, passes through the imaging lenses 22a, 22b, and enters the light receiving elements 21a, 21b. At this time, one fixed point (fixed position) on the cylindrical side surface (the rotating surface of the shaft 12 as a rotating body) through which the surface of the shaft 12 passes as the shaft 12 rotates in the light emitted from the light emitting element 20. The light reflected by the light receiving element 21a is received by the light receiving element 21a, and the light reflected by another fixed point (fixed position) is received by the light receiving element 21b. One fixed point (fixed position) and the other fixed point (fixed position) have the same position coordinates along the rotation direction of the shaft 12. That is, the reflection position of the light incident on the light receiving element 21a on the surface of the shaft 12 and the reflection position of the light incident on the light receiving element 21b on the surface of the shaft 12 are on a straight line extending in the extending direction of the shaft 12. The imaging lenses 22a and 22b image the surface of the shaft 12 on the light receiving elements 21a and 21b.

  Reference is made to FIG. This figure shows a part of a cross section perpendicular to the extending direction of the shaft 12 in the formation part of the slit 19a row. Slits 19 a having a slit width of about 40 μm are periodically formed along the rotation direction of the shaft 12 at intervals of about 40 μm.

  Reference is made to FIG. In this figure, a part of the cross section perpendicular to the extending direction of the shaft 12 in the formation part of the slit 19b row is shown together with that in the formation part of the slit 19a row. Also in the slit 19b row forming portion, slits 19b having a slit width of about 40 μm are periodically formed along the rotation direction of the shaft 12 at intervals of about 40 μm. The formation period of the slit 19b is equal to that of the slit 19a. However, the formation position of the slit 19 b is shifted from the formation position of the slit 19 a by a half pitch phase along the rotation direction of the shaft 12.

  The rotational position (rotation angle) of the shaft 12 is grasped based on the light emitted from the light emitting element 20 and reflected by the slit 19a, 19b formation region of the shaft 12 and detected by the light receiving elements 21a, 21b.

  FIG. 2 shows signals (analog signals obtained from the encoder unit 16) indicating the intensity of light reflected at the slits 19a and 19b and detected by the light receiving elements 21a and 21b, and reflection positions at the slits 19a and 19b. The correspondence with is shown. With reference to this figure, the method to grasp | ascertain the rotational position (rotation angle) of the shaft 12 is demonstrated.

  In the encoder section 16 of the galvano scanner according to the embodiment, slits 19 a and 19 b having a slit width of about 40 μm are formed at intervals of about 40 μm on the surface of the shaft 12 having a diameter of 7 mm. Accordingly, 512 convex portions and concave portions (slits 19a and 19b) are alternately arranged at the positions where the slits 19a and 19b are formed. In this drawing, the numbers 1 to 512 are given to the convex portions at the positions where the slits 19a and 19b are formed. Further, the convex portions at the positions where the slits 19a and 19b are formed generate reflected light having a relatively high intensity, and the concave portions generate reflected light having a relatively low intensity. For this reason, the analog signals indicating the intensity of light detected by the light receiving elements 21a and 21b are, for example, sinusoidal waves as illustrated.

  An analog signal (sine wave) is input to the interpolator. The interpolator A / D converts and digitizes the analog signals (sine waves) related to the light receiving elements 21a and 21b, and obtains the phase difference between them from the Lissajous waveform.

  A phase difference can be detected with high resolution by dividing one cycle of the Lissajous into multiple sections. For example, as in the embodiment, when the slit row is not two rows but only one row is formed, the resolution is 512 pulses per rotation of the shaft 12 (512 pulses / round, 360 ° / 1024), m By dividing, a resolution of 512 × m pulses / circulation is realized. In the case of 1000 division, the resolution is 512000 pulses / circumference.

  The rotation angle can be derived, for example, by counting the number of pulses after multiple division with a counter. By accumulating the rotation angles, the current rotation position (current rotation angle) of the shaft 12 is derived.

  The slits 19a and 19b can be formed by irradiating the surface of the shaft 12 with a laser beam. It is also possible to form a photoresist film on the surface of the shaft 12 or attach a photoresist film, and perform exposure, development and etching. For example, by forming the non-etched part (convex part) in black and the etched part (concave part) in white or vice versa, the light receiving elements 21a and 21b can effectively detect the reflected light in the slit 19a and 19b formation regions. be able to.

  FIG. 3 is a block diagram illustrating operation control of the galvano scanner according to the embodiment. The analog signal acquired by the “encoder unit” 16 (the light intensity signal detected by the light receiving elements 21a and 21b) is input to the “interpolator”. The interpolator A / D-converts and digitizes analog signals (sine waves) related to the light receiving elements 21a and 21b, obtains the phase difference between them from the Lissajous waveform, and outputs it. The information output from the interpolator is input to the “rotational position deriving unit”. The rotational position deriving unit includes a counter and a deriving unit.

  For example, the counter counts the number of pulses after dividing one Lissajous cycle. For example, the deriving unit derives the rotation angle of the shaft 12 and the current rotation position (current rotation angle) of the shaft 12 based on the count number of the counter.

  Information on the rotational position of the shaft 12 derived and grasped by the rotational position deriving unit is fed back to the position control loop and used for control to rotate the galvanometer mirror 10 to a desired position.

In rotating the galvanometer mirror 10 to a desired position by rotating the shaft 12, first, a "position command" is sent to the "position control amplifier" together with the current rotational position information of the shaft 12 output from the rotational position deriving unit. Entered. The position control amplifier generates and outputs a speed command that commands the rotation speed of the shaft 12 from the input information. The speed command output from the position control amplifier uses the current rotation speed information obtained by differentiating the current rotation position output from the rotation position deriving unit, and feed forward (FF) as the position control amplifier. It is input to the “speed amplifier” together with the derivative of the position command input to. The speed amplifier generates and outputs a current command for instructing a current to flow through the coil 14 from the input information in order to set the rotational speed of the shaft 12 to a desired value. The current command is input to the “current amplifier” together with the current value of the coil 14 through the “notch filter” that attenuates the frequency component of the resonance band. The current amplifier causes a current of a value calculated from input information to flow through the coil 14 and rotates the shaft 12 to rotate the mirror 10 of the galvano scanner to a desired position. The galvano scanner according to the embodiment includes a slit 19a. , 19b are formed on the shaft 12, light from the light emitting element 20 is reflected in the formation region and read by the light receiving elements 21a and 21b, and the rotational position (rotation angle) of the shaft 12 is grasped. For example, unlike the conventional galvano scanner shown in FIG. 4, since the hub and the disk are not attached to the shaft, the galvano scanner according to the embodiment can reduce the inertia of the rotating portion and realize high-speed operation. . Further, even when high speed operation is performed, the resonance frequency can be increased.

    Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto.

  For example, in the embodiment, the encoder unit 16 is installed on the side opposite to the galvanometer mirror 10 with the bearings 13a and 13b interposed therebetween, but may be installed on the same side as the galvanometer mirror 10. Moreover, installation between the bearings 13a and 13b is also possible.

  In the embodiment, the shaft 12 is made of SUS. However, it can be made of ceramic or the like.

  Furthermore, in the embodiment, the light emitted from one light emitting element 20 is received by the two light receiving elements 21a and 21b. However, different light emitting elements can be used for each light receiving element.

  Further, the slit need not be formed over the entire circumference of the shaft, and may be formed in a movable range of the galvanometer mirror, for example, in a range of 20 ° in the circumferential direction (rotation direction) of the shaft.

  Furthermore, in the example, a plurality of recesses (slits 19a and 19b) were formed in the shaft 12, and light from the light emitting element 20 was reflected in a recess forming region combined with the protrusions defined between the recesses. The recessed portion forming region is a region in which recessed portions and protruding portions are alternately arranged periodically along the rotation direction of the shaft 12. The convex portion generates reflected light having a relatively high intensity, and the concave portion generates reflected light having a relatively low intensity. For example, a linear scale tape in which white lines and black lines of equal width appear alternately at equal intervals is applied to the shaft 12 so that the line direction and the extending direction of the shaft 12 are parallel to each other, and the white line and the black line are adhered. You may reflect light in the formation area of a line. The light reflected by the white line is relatively strong and the light reflected by the black line is relatively weak. It is only necessary that a mark serving as a reference for detecting the position of the shaft 12 in the rotational direction is formed in the region where the light is reflected by the light intensity signal detected when the reflected light is received by the light receiving elements 21a and 21b. .

  In the embodiment, two slit rows are formed. However, when used for applications where the resolution is not important, the slit row may be one.

  It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like can be made.

  It can be suitably used for laser processing performed by irradiating a laser beam.

DESCRIPTION OF SYMBOLS 10 Mirror 11 Mirror mount 12 Shaft 13a, 13b Bearing 14 Coil 15a, 15b Magnet 16 Encoder part 17 Hub 18 Disk 19, 19a, 19b Slit 20 Light emitting element 21, 21a, 21b Light receiving element 22a, 22b Imaging lens

Claims (4)

A shaft that is rotatable around the center of rotation and has a first position detection mark formed along the direction of rotation;
A galvanometer mirror fixed to the shaft and reflecting an incident light beam;
A rotation mechanism for rotating the shaft around the rotation center;
A light emitter that makes light incident on the first position detection mark of the shaft;
A light receiver that is reflected by the first position detection mark of the shaft and that receives light from the light emitter;
A galvano scanner having a rotation position deriving unit for deriving a position of the shaft in the rotation direction based on light incident on the light receiver.   The first position detection mark includes a first region and a second region that are alternately and periodically arranged in a first period along a rotation direction of the shaft, and the first region includes: The galvano scanner according to claim 1, wherein reflected light having higher intensity than that of the second region is generated.   Furthermore, it includes a second position detection mark formed at a position different from the first position detection mark along the length direction of the shaft, and the second position detection mark extends in the rotation direction of the shaft. A third region and a fourth region that are periodically and alternately arranged in the first period, and the third region emits reflected light having a stronger intensity than the fourth region. The galvano scanner according to claim 2, wherein the galvano scanner is generated and is out of phase with the phase of the first position detection mark.   The galvano scanner according to claim 3, wherein the second region and the fourth region are concave portions formed in the shaft.

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