KR20130105333A - Galvano scanner - Google Patents

Abstract

PURPOSE: A galvano-scanner is provided to promote miniaturization by securing a reflection surface in a desired region. CONSTITUTION: A rotary mirror (20) is fixed in one end of a rotary shaft through a fixture (24). An encoder (22) is mounted in the other end of the rotary shaft. A motor (23) generates torque in the central part of the rotary shaft. The rotary shaft is rotatably supported by a bearing (26) in both sides of a motor. The rotary shaft, rotary mirror and encoder are reciprocally rotated in a specific range based on a rotational center line (31).

Description

Galvanos Scanner

This application claims priority based on Japanese Patent Application No. 2012-053998, filed March 12, 2012. The entire contents of which are incorporated herein by reference.

The present invention relates to a galvanoscopy scanner that reflects a light beam by a rotating mirror rotating within a predetermined angle range.

In a laser drill or the like, a galvano scanner is used to scan a laser beam. The galvanos scanner includes a rotating mirror and a motor for rotating the rotating mirror. When the rotating mirror reciprocates at high speed, deformation occurs in the rotating shaft or the rotating mirror, and resonance occurs. Patent Literature 1 discloses a galvanoscancer that raises a resonance frequency by supporting a rear surface of a rotating mirror with a plate-shaped member to increase rigidity. In this galvanosk scanner, the shaft center of a rotating shaft passes through the center of gravity of a rotating mirror and a plate-shaped member. As a result, resonance due to the asymmetry of the rotating mirror and the plate-shaped member is suppressed.

Japanese Patent Application Laid-Open No. 7-270701

In order to scan the laser beam in two directions, the x direction and the y direction, two galvanos scanners for x and y are used. The laser beam incident on the second stage galvanos scanner vibrates in one direction by the first stage galvanos scanner. For this reason, the rotation mirror of the galvanos scanner of the 2nd stage should be made larger than the rotation mirror of the galvanos scanner of a 1st stage. The larger the rotation mirror, the greater the moment of inertia, and thus the worse the response characteristics.

An object of the present invention is to provide a galvanoscopy scanner capable of suppressing a decrease in response characteristics even when the rotating mirror becomes large.

According to one aspect of the present invention,

Rotation axis,

A reflection surface parallel to the rotation center line of the rotation axis, the planar shape of the reflection surface is asymmetric with respect to the rotation center line, and with respect to the in-plane direction of the reflection surface, the center of gravity is the rotation center line Swivel mirror in position overlapping with

There is provided a galvano scanner.

According to another aspect of the present invention,

Rotation axis,

A rotating mirror mounted to the rotating shaft, the rotating mirror having a reflective surface parallel to the center of rotation of the rotating shaft;

A first reinforcing rib formed on the rear surface of the rotating mirror and extending from the mounting portion to the rotating shaft toward the tip along the rotation center line and tapering towards the tip;

A plurality of second reinforcing ribs formed on the rear surface of the rotating mirror and branching from the first reinforcing ribs and extending in a direction inclined to the side of the tip of the rotating mirror from a direction perpendicular to the rotation center line;

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The tip of the rotating mirror is provided with a galvanoscanner which is a free end.

By making the plane shape of the reflecting surface asymmetrical with respect to the rotation center line, the reflecting surface can be secured only in a desired area, and the size can be reduced. Even if the shape of the reflecting surface is asymmetrical, the excitation of the buckling mode can be suppressed by placing the center of gravity on the center of rotation.

1 is a schematic diagram of a laser drill using a galvanoscopy scanner according to the first embodiment.
FIG. 2A is a side view of the galvanoscopy scanner according to the first embodiment, FIG. 2B is a front view of the rotating mirror, and FIG. 2C is a rear view of the rotating mirror.
3A is a side view of the galvanoscopy scanner according to the first embodiment, and FIG. 3B is a sectional view of the rotating mirror.
4A and 4B are schematic diagrams of galvanos scanners as simulation targets, and FIG. 4C is a graph showing simulation results.
5A and 5B are schematic diagrams of galvanos scanners as simulation targets, and FIG. 5C is a graph showing simulation results.
6A and 6B are respectively a front view and a rear view of a rotation mirror of a galvanoscopy scanner according to a modification of the first embodiment.
7A and 7B are respectively a front view and a rear view of a rotating mirror of a galvanoscopy scanner according to the second embodiment.

[Example 1]

1, the schematic diagram of the laser drill using the galvanoscopy scanner which concerns on Example 1 is shown. The laser beam emitted from the laser light source 10 passes through the bending mirror 11, the first stage galvanos scanner 12, the second stage galvanos scanner 13, and the fθ lens 14. It enters into (15). However, a beam expander, mask, lens, etc. are arrange | positioned as needed. An xy rectangular coordinate system whose surface of the object to be processed 15 is an xy plane is defined.

The first stage galvanos scanner 12 moves the incident point of the laser beam in the x direction on the surface of the object to be processed 15. When the traveling direction of the laser beam is vibrated by the first stage galvanos scanner 12, the incident point of the second stage galvanos scanner 13 into the rotation mirror 20 moves in the x direction. The second stage galvanos scanner 13 moves the incident point of the laser beam in the y direction on the surface of the object to be processed 15. The fθ lens 14 focuses the laser beam on the surface of the object to be processed and makes vertical incidence.

In FIG. 2A, the schematic side view of the galvano scanner 13 of the 2nd step | paragraph is shown. The rotating mirror 20 is fixed to one end of the rotating shaft 21 via the fixing tool 24. The encoder 22 is attached to the other end of the rotating shaft 21. The motor 23 generates torque in the center portion of the rotation shaft 21. The rotating shaft 21 is rotatably supported by the bearing 26 on both sides of the motor 23. The rotating shaft 21, the rotating mirror 20, and the encoder 22 are reciprocally rotated within a predetermined range around the rotation center line 31.

In FIG. 2B, the front view of the rotating mirror 20 when it faces the reflection surface 20A of the rotating mirror 20 in front is shown. The reflective surface 20A is parallel to the rotation center line 31. When the laser beam is scanned on the first stage galvanos scanner 12 (FIG. 1), the beam end surface 30 of the laser beam moves along the rotation center line 31 on the reflecting surface 20A. Since the reflective surface 20A is inclined with respect to the advancing direction of the incident laser beam, the beam end surface 30 which cut out the laser beam by the reflective surface 20A becomes an ellipse. The beam end face 30B when the long end of the beam end surface 30A when the laser beam was vibrated to one end by the galvanos scanner 12 (FIG. 1) of 1st stage, and the end surface to the other end. The major axis of is inclined in the opposite direction with respect to the center of rotation 31.

20 A of reflecting surfaces have an external shape slightly larger than the external shape of the area | region to which the beam cross section 30 moves when a laser beam is vibrated with the galvanos scanner 12 (FIG. 1) of a 1st stage | paragraph. For example, the external shape of the reflective surface 20A includes a pair of straight portions parallel to the rotation center line 31 and a curved portion connecting the ends of the pair of straight portions. The length of a pair of linear part mutually differs. The curved portion is smoothly connected to the straight portion and has a convex shape toward the outside. In other words, the reflective surface 20A has a shape in which a pair of trapezoidal inclined sides are inflated outward.

The outer shape of the reflecting surface 20A is slightly larger than the outer shape of the moving range of the beam end face 30 in order to secure a margin for absorbing mounting errors of the optical system, manufacturing deviation of the rotating mirror 20, and the like. . The holding part 43 is formed in the edge of the rotating mirror 20. The holding part 43 is gripped by the fixture 24 (FIG. 2A), and the rotating mirror 20 is fixed to the rotating shaft 21. As shown in FIG.

Since the beam end surfaces 30A and 30B are inclined in mutually opposite directions with respect to the rotation center line 31, the external shape of the reflection surface 20A becomes asymmetrical with respect to the rotation center line 31. As shown in FIG. More specifically, one area of the reflection surface 20A is wider than the other area with the rotation center line 31 as the center. For this reason, when the rotating mirror 20 is made into uniform thickness, the center of gravity G of the rotating mirror 20 will deviate from the rotating center line 31. FIG. In the first embodiment, as described later, the center of gravity G of the rotation mirror 20 is positioned on the rotation center line 31 with respect to the in-plane direction of the reflective surface 20A.

In FIG. 2C, the rear view of the rotating mirror 20 is shown. The first reinforcing rib 41 and the second reinforcing rib 42 are formed on the rear surface 20B of the rotating mirror 20 to increase rigidity. The first reinforcing rib 41 extends from the grip portion 43 along the rotation center line 31 toward the tip of the rotation mirror 20. The width of the first reinforcing rib 41 is tapered toward the tip.

The second reinforcing rib 42 branches off from the first reinforcing rib 41. The second reinforcing ribs 42 extend from the direction perpendicular to the rotation center line 31 in the inclined direction inclined in the direction of the tip of the rotation mirror 20. The number of the second reinforcing ribs 42 (two in FIG. 2C) arranged around the rotation center line 31 with the area of the reflective surface 20A relatively larger is the area of the reflective surface 20A. The number of the second reinforcing ribs 42 disposed on the relatively smaller side (three in Fig. 2C) is smaller. By adjusting the number of the second reinforcing ribs 42, the center of gravity G of the rotation mirror 20 can be positioned on the rotation center line 31 with respect to the in-plane direction of the reflection surface 20A.

Instead of adjusting the number of second reinforcing ribs 42, the height of the first reinforcing ribs 41 and the second reinforcing ribs 42 is made non-uniform, so that the center of rotation of the reflection surface 20A is in the plane of the plane. (31) may pass through the center of gravity (G). As an example, even if the second reinforcing rib 42 disposed on the side where the area of the reflective surface 20A is relatively larger than the second reinforcing rib 42 disposed on the side where the area of the reflective surface 20A is relatively smaller, do. In addition, even if the second reinforcing rib 42 disposed on the side where the area of the reflective surface 20A is relatively larger than the second reinforcing rib 42 disposed on the side where the area of the reflective surface 20A is relatively smaller, do.

As a material of the rotating mirror 20, for example, beryllium is used. In the production of the rotating mirror 20, first, a powder of beryllium is sintered to obtain a structure close to the final shape. Then, the rotating mirror 20 is manufactured by shaving the surface of this structure and adjusting a shape.

In FIG. 3A, the schematic side view of the state which rotated the rotation mirror 20 of the 2nd-stage galvanoscopy scanner 13 by 90 degrees from the state of FIG. 2A is shown. The holding part 43 of the rotating mirror 20 is fitted to the fixing tool 24 and is fixed to the rotating shaft 21. The rotating mirror 20 and the fastener 24 are mutually fixed by an adhesive agent, for example. The first reinforcing ribs 41 are formed on the back surface 20B.

3B, sectional drawing of the rotating mirror 20 and the fixture 24 is shown. The height from the back surface 20B to the upper surface (surface facing downward in FIG. 3B) is higher than the height from the back surface 20B to the reflective surface 20A. The center of gravity G of the rotating mirror 20 is located on the side opposite to the reflective surface 20A with respect to the rear surface 20B. By adjusting the heights of the first reinforcing ribs 41 and the second reinforcing ribs 42 (FIG. 2C), the position of the center of gravity G can be adjusted with respect to the thickness direction of the rotating mirror 20. In Example 1, the height of the 1st reinforcement rib 41 and the 2nd reinforcement rib 42 is set so that the rotation center line 31 may pass through the center of gravity G. As shown in FIG.

Conventionally, the shape of the reflective surface 20A is symmetrical with respect to the rotation center line 31. For this reason, each of the reflective surfaces 20A on both sides should be the same as or larger than the relatively larger reflective surface 20A shown in FIG. 2B with the rotation center line 31 as the center. Therefore, the weight of the rotating mirror 20 becomes heavy. As in the first embodiment, by making the shape of the reflective surface 20A asymmetrical with respect to the rotation center line 31, the rotation mirror 20 can be miniaturized and reduced in weight.

With reference to FIG. 4A-FIG. 4C, the effect of the galvano scanner by Example 1 is demonstrated. The response characteristics of the galvanoscopy scanner shown in FIG. 4A and FIG. 4B were calculated | required by simulation. The galvanos scanner shown in Fig. 4A has the same configuration as the galvanos scanner according to the first embodiment described above. The galvano scanner shown in FIG. 4B is supported by a bearing 27 at the tip of the rotating mirror 20. That is, the rotation shaft 21 is supported at three points of two bearings 26 which support the rotation shaft 21 and the bearing 27 which supports the rotation mirror 20 at the front-end | tip. In contrast, the rotary shaft 21 of the galvanos scanner shown in Fig. 4A is supported at two points.

When the structure which supports a rotating shaft at three points is employ | adopted, the vibration of a bending mode will be excited when the bearing center of three bearings is out. By supporting the rotating shaft 21 at two points, the excitation of the bending mode is suppressed. However, if the tip of the rotating mirror 20 is the open end, the vibration of the buckling mode is likely to be excited when the center of gravity G of the rotating mirror 20 is out of the center of rotation.

4C shows the analysis results by the finite element method of the speed open loop frequency response characteristics of gain and phase. The horizontal axis represents the frequency in logarithmic scale, the left vertical axis represents the gain in units of "dB", and the right vertical axis represents the phase in units of "degrees". The input of the open loop frequency response characteristic is a sine wave current supplied to the motor 23, and the output is a rotation speed of the motor 23. The solid line 4A shows the response characteristic of the two point support galvanos scanner shown in FIG. 4A, and the broken line 4B shows the response characteristic of the three point support galvanos scanner shown in FIG. 4B. Even in a two-point support galvanoscancer, resonance does not occur in the frequency region lower than the anti-resonance point. That is, resonance of the buckling mode does not occur. This is because the center of gravity G of the rotation mirror 20 is located on the rotation center line 31, as shown to FIG. 2B, FIG. 2C, FIG. 3B.

Next, with reference to FIG. 5A-FIG. 5C, the effect of miniaturizing the rotating mirror 20 is demonstrated. The response characteristics of the galvano scanner shown in Figs. 5A and 5B were obtained by simulation.

The galvanos scanner shown in FIG. 5A has the same configuration as the galvanos scanner of the first embodiment, and the reflecting surface 20A of the rotation mirror 20 is asymmetric with respect to the rotation center line 31. The reflecting surface of the rotation mirror 20 of the galvanoscopy scanner shown in FIG. 5B is symmetrical with respect to the rotation center line 31. For this reason, the rotating mirror 20 shown in FIG. 5B is heavier than the rotating mirror 20 shown in FIG. 5A.

Fig. 5C shows the analysis results by the finite element method of the frequency open loop frequency response characteristics of gain and phase. The horizontal axis and the vertical axis are the same as the horizontal axis and the vertical axis of the graph shown in FIG. 4C. It can be seen that the frequency of the anti-resonance point of the galvano scanner shown in FIG. 5A is higher than the frequency of the anti-resonance point of the galvano scanner shown in FIG. 5B. This is because the inertia moment is reduced by miniaturizing the rotating mirror 20.

In the first embodiment, as shown in FIG. 2B, when the laser beam is scanned by the first stage galvanos scanner 12, the beam end surface 30 of the laser beam is formed by the second stage galvanos scanner 13. It moved in the direction parallel to the rotation center line 31. As shown in FIG. Depending on the postures of the galvanoscopy scanners 12 and 13 in the first and second stages, the moving direction of the beam end face 30 may not be parallel to the rotation center line 31.

6A, the front view of the rotating mirror 20 in the case where the moving direction of the beam cross section 30 and the rotation center line 31 are not parallel is shown. The linear portion of the outer shape of the reflective surface 20A is slightly inclined with respect to the rotation center line 31. Also in this case, as described later, the center of gravity G of the rotation mirror 20 is positioned on the rotation center line 31.

6B, the rear view of the rotating mirror 20 is shown. The first reinforcing ribs 41 extend along the rotation center line 31, not in the moving direction of the beam end face 30 (FIG. 6A). The planar shape and height of the first reinforcement ribs 41 and the second reinforcement ribs 42 are set such that the center of gravity G is located on the rotation center line 31.

[Example 2]

7A and 7B show front and rear views of the rotating mirror of the galvanoscopy scanner according to the second embodiment, respectively. Hereinafter, the difference with the galvanoscopy scanner which concerns on the said Example 1 is demonstrated, and description is abbreviate | omitted about the same structure.

As shown to FIG. 7A, the reflecting surface 20A of the rotation mirror 20 of the galvano scanner which concerns on Example 2 is symmetric about the rotation center line 31. As shown in FIG. As shown in FIG. 7B, the first reinforcing rib 41 extends along the rotation center line 31 from the grip portion 43 in the same manner as in the first embodiment, and becomes thinner toward the tip. The second reinforcing rib 42 branches from the first reinforcing rib 41 similarly to the first embodiment. In addition, the second reinforcing ribs 42 extend in a direction inclined toward the distal end of the rotation mirror 20 from a direction perpendicular to the rotation center line 31. The first reinforcing rib 41 and the second reinforcing rib 42 have a planar shape symmetrical with respect to the rotation center line 31. Since the reflective surface 20A is symmetrical with respect to the rotation center line 31 and the first reinforcing rib 41 and the second reinforcing rib 42 are also symmetrical with respect to the rotation center line 31, the reflective surface 20A With respect to the in-plane direction of, the center of gravity G of the rotation mirror 20 is located on the rotation center line 31.

Since the first reinforcing rib 41 is tapered from the grip portion 43 toward the distal end, the moment of inertia is reduced as compared with the case of the equal width. As a result, the response characteristic can be improved. In particular, since the tip is relatively light, the free tip can be provided without supporting the tip with a bearing. Thereby, the excitation of the vibration of a bending mode can be suppressed.

In Example 1 and Example 2, the example in which the center of gravity G of the rotation mirror 20 is located on the rotation center line 31 was shown. However, the center of gravity G may deviate slightly from the rotation center line 31 due to the deviation of the machining precision. When the deviation from the rotation center line 31 to the center of gravity G is 100 μm or less, it can be said that the center of gravity G is substantially positioned on the rotation center line 31.

While the present invention has been described with reference to the above embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various changes, improvements, combinations, and the like are possible.

10 laser light source
11 bending mirror
12 first-stage galvanos scanner
13 Galvanos scanner of the second step
14 fθ lens
15 Object
20 rotating mirror
20A reflective surface
20B back
21 Rotary shaft
22 encoder
23 Motor
24 fixture
26, 27 bearing
30, 30A, 30B beam cross section
31 center of rotation
41 1st reinforcement rib
42 Second Reinforcement Rib
43 grip

Claims (6)

A rotating shaft,
A reflection surface parallel to the rotation center line of the rotation axis, the planar shape of the reflection surface is asymmetric with respect to the rotation center line, and with respect to the in-plane direction of the reflection surface, the center of gravity is the rotation center line Swivel mirror in position overlapping with
Galvanos scanner with. The method according to claim 1,
A galvanoscanner at a position in which the center of gravity of the rotating mirror overlaps with the center of rotation with respect to the thickness direction perpendicular to the reflective surface. The method according to claim 1 or 2,
Galvanoscancers, which are formed on the rear surface of the rotating mirror, extend from the mounting portion to the rotating shaft toward the tip along the rotation center line and further have a first reinforcing rib tapering toward the tip. The method according to claim 3,
A galvano further formed on the rear surface of the rotating mirror and further having a plurality of second reinforcing ribs branching from the first reinforcing ribs and extending in a direction inclined toward the distal end of the rotating mirror from a direction perpendicular to the rotation center line. scanner. The method according to any one of claims 1 to 4,
The tip of the rotating mirror is a free end galvanoscanner. A rotating shaft,
A rotating mirror mounted to the rotating shaft, the rotating mirror having a reflective surface parallel to the center of rotation of the rotating shaft;
A first reinforcing rib formed on the rear surface of the rotating mirror and extending from the mounting portion to the rotating shaft toward the tip along the rotation center line and tapering toward the tip;
A plurality of second reinforcing ribs formed on the rear surface of the rotating mirror and branching from the first reinforcing ribs and extending in a direction inclined toward the distal end of the rotating mirror from a direction perpendicular to the rotation center line;
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The tip of the said rotating mirror is a galvanosscanner which becomes a free end.

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