阅读说明：本技术 多面镜、导光装置以及光扫描装置 (Polygonal mirror, light guide device, and optical scanning device ) 是由 中泽睦裕 大串修己 于 2020-02-06 设计创作，主要内容包括：多面镜以旋转轴为中心进行旋转。在多面镜的多个边中的2个以上的边上分别配置有第一反射面以及第二反射面。所述第一反射面形成为相对于与所述旋转轴垂直的平面倾斜的平面状。所述第二反射面形成为相对于与所述旋转轴垂直的平面倾斜的平面状。入射到该多面镜的光通过所述第一反射面反射,然后由所述第二反射面反射。在多个所述边之间,第一反射面的相对于与所述旋转轴垂直的平面倾斜的方向、以及沿旋转轴的方向的所述第一反射面与所述第二反射面之间的距离中至少有一个不同。(The polygon mirror rotates about a rotation axis. The first reflecting surface and the second reflecting surface are disposed on 2 or more sides of the polygon mirror. The first reflection surface is formed in a planar shape inclined with respect to a plane perpendicular to the rotation axis. The second reflecting surface is formed in a planar shape inclined with respect to a plane perpendicular to the rotation axis. Light incident to the polygon mirror is reflected by the first reflection surface and then reflected by the second reflection surface. At least one of a direction of the first reflecting surface inclined with respect to a plane perpendicular to the rotation axis and a distance between the first reflecting surface and the second reflecting surface in the direction of the rotation axis is different between the plurality of sides.)

1. A polygon mirror that rotates around a rotation axis, characterized in that:

a first reflection surface formed in a planar shape inclined with respect to a plane perpendicular to the rotation axis and a second reflection surface formed in a planar shape inclined with respect to a plane perpendicular to the rotation axis are arranged on 2 or more sides among the plurality of sides, respectively,

the light incident on the polygon mirror is reflected by the first reflection surface, then reflected by the second reflection surface, and

at least one of a direction of the first reflecting surface inclined with respect to a plane perpendicular to the rotation axis and a distance between the first reflecting surface and the second reflecting surface in the rotation axis direction is different between the plurality of sides.

2. The polygon mirror according to claim 1, wherein 2 sides in which the first reflecting surface is inclined with respect to a plane perpendicular to the rotation axis is included among the plurality of sides, and the first reflecting surface is inclined with respect to the plane perpendicular to the rotation axis

The distance between the first reflection surface and the second reflection surface in the rotation axis direction is equal between one side and the other side of the 2 sides.

3. The polygon mirror according to claim 1 or 2, wherein 2 sides in which the first reflection surface is inclined with respect to a plane perpendicular to the rotation axis in the same direction are included in the plurality of sides, and the first reflection surface is inclined with respect to the plane perpendicular to the rotation axis, and

the distance between the first reflection surface and the second reflection surface is different between one side and the other side of the 2 sides.

4. A light guide device is characterized by comprising:

a polygonal mirror according to any one of claims 1 to 3;

a first light reflector configured to guide light deflected on one of the plurality of sides of the polygon mirror to a first scanning area; and

and a second light reflector that guides the light deflected on the other side to a second scanning area different from the first scanning area.

5. An optical scanning device characterized in that:

comprises a light guide device according to claim 4, and

the first light reflecting part and the second light reflecting part are respectively provided with a plurality of reflecting surfaces for reflecting light,

the first light reflecting unit and the second light reflecting unit reflect light emitted from the rotating polygon mirror 2 or more times and guide the light to an arbitrary irradiated point included in a linear scanning line,

the optical path length from the incident position of the light to the polygon mirror to the irradiated point is substantially constant at all irradiated points on the scanning line

The scanning speed of the light guided from the polygon mirror by the first light reflecting unit and the second light reflecting unit on the scanning line is substantially constant.

Technical Field

The present invention relates generally to a light reflection device that deflects and reflects incident light.

Background

Conventionally, a technique of guiding light from a light source by a polygon mirror or the like to scan along a linear scanning line has been widely used in an image forming apparatus, a laser processing apparatus, and the like. Patent document 1 discloses an optical scanning device including a polygon mirror.

The optical scanning device of patent document 1 includes a light projecting means and a light reflecting means. The light projecting means includes a polygon mirror that reflects light incident from a predetermined direction on a reflection surface of each side of a regular polygon of a rotating polygon mirror, and emits light while rotating. And a light reflection means for reflecting the light emitted from the light projection means by the plurality of reflection units and guiding the light to an arbitrary irradiated point on a predetermined scanning line.

[ Prior art documents ]

[ patent document ]

Patent document 1: japanese patent No. 5401629

Disclosure of Invention

Technical problem to be solved by the invention

However, the configuration of patent document 1 constitutes the entire scanning line with a light deflection range corresponding to one side of the polygon mirror. Therefore, if a long scanning line is to be realized, it is necessary to secure a certain light deflection angle range, and it is difficult to increase the number of sides. In the case where the polygon of the polygon mirror has a small number of sides, when light is reflected in the vicinity of the polygon vertex, distortion of scanning may increase, and it is desired to improve such a situation.

In view of the above, an object of the present invention is to provide a polygon mirror capable of switching a scanning range at high speed and performing scanning with less distortion.

Technical scheme for solving problems

The problems to be solved by the present invention are as described above, and means for solving the problems and effects thereof will be described below.

According to a first aspect of the present invention, there is provided a polygon mirror of the following structure. That is, the polygon mirror rotates around the rotation axis. A first reflection surface and a second reflection surface are disposed on 2 or more sides of the polygon mirror. The first reflecting surface is formed in a planar shape inclined with respect to a plane perpendicular to the rotation axis. The second reflecting surface is formed in a planar shape inclined with respect to a plane perpendicular to the rotation axis. Light incident on the polygon mirror is reflected by the first reflecting surface and then reflected by the second reflecting surface. At least one of a direction of the first reflecting surface inclined with respect to a plane perpendicular to the rotation axis and a distance between the first reflecting surface and the second reflecting surface in the direction of the rotation axis is different between the plurality of sides.

Thus, the position (emission position) at which light is reflected on the emission surface is discontinuously switched in the rotation axis direction in accordance with the rotation of the polygon mirror. Therefore, by guiding the emitted light to different scanning regions according to the emission position in the rotation axis direction, it is possible to scan a plurality of regions while switching the scanning regions at high speed. In other words, the number of sides of the polygon mirror can be increased, so that a configuration for scanning a plurality of areas can be easily realized. This can shorten the polygon mirror, and thus can reduce scanning distortion at both ends of each scanning area.

According to a second aspect of the present invention, there is provided a light guide device configured as follows. That is, the light guide device includes the polygon mirror, the first light reflecting portion, and the second light reflecting portion. The first light reflecting unit guides light deflected by one of the plurality of sides of the polygon mirror to a first scanning area. The second light reflector guides the light deflected on the other side to a second scanning area different from the first scanning area.

Therefore, by guiding light to a plurality of scanning regions, various parts can be scanned flexibly. Since the scanning distortion in each scanning region is reduced, high-quality scanning can be performed as a whole.

According to a third aspect of the present invention, there is provided an optical scanning device having the following structure. That is, the optical scanning device includes the light guide device. The first light reflecting section and the second light reflecting section each include a plurality of reflecting surfaces that reflect light. The first light reflecting unit and the second light reflecting unit reflect light emitted from the rotating polygon mirror 2 or more times, respectively, and guide the light to an arbitrary irradiated point included in a linear scanning line. The optical path length from the incident position of the light on the polygon mirror to the irradiated point is substantially constant at all irradiated points on the scanning line. The scanning speed of the light guided from the polygon mirror by the light reflecting section on the scanning line is substantially constant.

Therefore, by scanning while switching the plurality of scanning regions, the entire linear scanning can be performed over a long distance. Incidentally, when the rotational phase of the polygon mirror is a rotational phase in which the irradiation range of the incident light covers a portion corresponding to the vertex of the polygon, the light intensity of the reflected light is unstable and cannot be used in the light scanning in practice. Further, in the case of a configuration in which the deflection angle range of the outgoing light corresponding to one side of the polygon mirror is divided and guided to different scanning regions, the same cannot be applied to the optical scanning when the angle of the outgoing light approaches the rotational phase of the divided boundary. In this regard, in the above configuration, the rotational phase of the polygon mirror that irradiates the polygon vertex with incident light and the rotational phase of the polygon mirror corresponding to switching of the scanning area can be made to be common. Accordingly, the range of the rotational phase of the polygon mirror that cannot be used for optical scanning is difficult to increase, and therefore, the polygon mirror can be effectively used for optical scanning, and scanning with less distortion can be realized.

Effects of the invention

According to the present invention, it is possible to provide a polygon mirror capable of switching a scanning range at high speed and performing scanning with less distortion.

Drawings

Fig. 1 is a perspective view schematically showing the configuration of a laser processing apparatus according to an embodiment of the present invention;

fig. 2 is a schematic view showing an optical path until a laser beam irradiated from a laser oscillator is irradiated onto a workpiece;

fig. 3 is a perspective view of the polygon mirror;

fig. 4 is a perspective view showing a state in which the emission position at which the laser beam is emitted from the polygon mirror is switched as the polygon mirror rotates;

fig. 5 is an exploded perspective view of the polygon mirror;

fig. 6 is a schematic diagram illustrating a state where the position of a virtual circular arc, which is a locus of which the focal point moves due to deflection of the laser light ray by rotation of the polygon mirror, is converted by the second light guiding part;

fig. 7 is a perspective view showing the polygon mirror and the second light guide;

fig. 8 is a schematic view illustrating irradiation of laser beams to different irradiation regions by switching the emission positions of the laser beams from the polygon mirror;

FIG. 9 is a view schematically showing an optical path of a laser beam before being reflected by a polygon mirror and irradiated on a workpiece;

fig. 10 is a perspective view of a polygon mirror of a first modification;

fig. 11 is a perspective view of a polygon mirror of a second modification;

fig. 12 is a schematic view showing a configuration of a second light guide portion corresponding to the polygon mirror of the second modification; and

fig. 13 is a schematic view showing a third modification of the second light guide unit.

Detailed Description

Embodiments of the present invention will be described below with reference to the drawings. Fig. 1 is a perspective view schematically showing the configuration of a laser processing apparatus 100 according to an embodiment of the present invention. Fig. 2 is a schematic diagram showing an optical path until the laser beam irradiated from the laser oscillator 21 is irradiated to the workpiece 10. Fig. 3 is a perspective view of the polygon mirror 5. Fig. 4 is a perspective view showing a state in which the emission position at which the laser beam is emitted from the polygon mirror 5 is switched as the polygon mirror 5 rotates. Fig. 5 is an exploded perspective view of the polygon mirror 5.

A laser processing apparatus (optical scanning apparatus) 100 shown in fig. 1 can process a plate-shaped workpiece 10 with a laser beam by scanning with the laser beam. Various machining operations include, for example, dicing of the workpiece 10, and patterning to remove a thin film formed on the surface of the workpiece 10 serving as a substrate.

The laser processing apparatus 100 of the present embodiment performs the processing work by scanning the generated laser beam (light) on the workpiece 10. The scanning means that the irradiation position of light such as laser light is changed in a predetermined direction.

The laser processing apparatus 100 mainly includes a workpiece conveying device 1, a laser unit 2, and a control device 3.

The workpiece conveying apparatus 1 conveys a workpiece 10 in a horizontal posture in a predetermined direction at a constant speed. As shown in fig. 1, the horizontal posture is a posture in which the thickness direction of the workpiece 10 is the vertical direction.

The laser unit 2 generates a laser light and scans the workpiece 10 by the laser light. The detailed structure of the laser unit 2 will be described later.

The controller 3 controls the operations of the workpiece conveying device 1 and the laser oscillator 21. The control device 3 can be realized by a computer, which is configured by, for example, a CPU, a ROM, a RAM, a timer, and the like.

Next, the laser unit 2 will be described in detail. The laser unit 2 includes a laser oscillator 21 and a light guide device 22.

The laser oscillator 21 serves as a light source of laser light. The laser oscillator 21 generates a pulse laser beam having a short time width by pulse oscillation. The time width of the pulsed laser is not particularly limited, and may be set to a short time interval, for example, a nanosecond, picosecond, or femtosecond. The laser oscillator 21 can also generate CW (continuous wave) laser light by continuous wave oscillation. The laser oscillator 21 irradiates a laser beam to the light guide 22.

The light guide 22 guides the laser beam generated by the laser oscillator 21 to the workpiece 10. The light guide device 22 includes optical components such as lenses and prisms.

As shown in fig. 2, the light guide device 22 of the present embodiment includes a first light guide section 4, a polygon mirror 5, and a second light guide section (light guide section) 6. At least a part of these optical components is disposed inside the housing 22a of the light guide device 22.

The first light guide section 4 is composed of an optical component for guiding the laser beam generated by the laser oscillator 21 to the polygon mirror 5. The first light guide section 4 includes an introduction lens 41, an introduction prism 42, a first introduction mirror 43, and a second introduction mirror 44 in this order from the laser oscillator 21 side along the optical path of the laser beam.

The introduction lens 41 is used to focus the laser beam generated by the laser oscillator 21 on a focal point. The laser beam having passed through the introduction lens 41 is guided to the polygon mirror 5 via the introduction prism 42, the first introduction mirror 43, and the second introduction mirror 44.

The introduction prism 42, the first introduction mirror 43, and the second introduction mirror 44 constitute an optical unit on the upstream side of the plurality of mirrors 5 on the optical path, which bends the optical path to secure the optical path length necessary for the focal point to be located on the surface of the work 10. Further, optical components constituting the first light guide 4 may be omitted as appropriate, or another prism or mirror may be added as appropriate between the introduction lens 41 and the polygon mirror 5. The position of the introduction lens 41 may be in front of the polygon mirror 5 (upstream side of the large number of mirrors 5 in the optical path). That is, a part or all of the introduction prism 42, the first introduction mirror 43, and the second introduction mirror 44 may be disposed on the upstream side of the introduction lens 41.

The polygon mirror 5 is mounted to be rotatable about a rotation axis 5a passing through the center thereof. When the polygon mirror 5 is viewed along the rotation axis 5a, the polygon mirror 5 has a regular polygon shape. In the present embodiment, the polygon of the polygon mirror 5 is a hexadecagon having 16 sides. However, the number of sides of the polygon mirror 5 is arbitrary.

As shown in fig. 3, the polygon mirror 5 includes a plurality of first reflecting surfaces 51 and a plurality of second reflecting surfaces 52. Specifically, one first reflection surface 51 and one second reflection surface 52 are formed on each side of the polygonal mirror 5 formed in a polygonal shape. The first reflection surface 51 and the second reflection surface 52 are arranged so as to correspond to each other.

The first reflecting surface 51 and the second reflecting surface 52 are formed in a planar shape. The first reflecting surfaces 51 are arranged side by side around the rotation shaft 5 a. The second reflecting surfaces 52 are arranged side by side around the rotating shaft 5 a.

The plurality of first reflecting surfaces 51 are all arranged obliquely with respect to a virtual plane perpendicular to the rotation axis 5 a. On any 2 sides adjacent in the circumferential direction among the sides that the polygon of the polygon mirror 5 has, the respective first reflection surfaces 51 are inclined with respect to a virtual plane perpendicular to the rotation axis 5a at opposite orientations and at equal angles (specifically, 45 °) to each other. The position at which the first reflecting surface 51 is provided does not change in the direction of the rotation axis 5a, regardless of which side of the polygon mirror 5 has.

The plurality of second reflecting surfaces 52 are arranged obliquely with respect to a virtual plane perpendicular to the rotation axis 5 a. On any 2 sides adjacent in the circumferential direction among the sides which the polygon of the polygon mirror 5 has, the respective second reflecting surfaces 52 are inclined with respect to a virtual plane perpendicular to the rotation axis 5a in opposite orientations and at equal angles (specifically, 45 °) to each other. In any 2 of the sides adjacent to each other in the circumferential direction, the positions where the second reflection surfaces 52 are provided are different from each other in the direction of the rotation axis 5 a.

The position and the inclination direction of the second reflecting surface 52 correspond to the inclination direction of the first reflecting surface 51 corresponding to the second reflecting surface 52 on the side. Accordingly, the second reflecting surface 52 and the first reflecting surface 51 are arranged so as to form a V-shape on any side of the polygon mirror 5.

The laser beam (incident light) guided by the second guiding mirror 44 irradiates the polygon mirror 5 in a direction perpendicular to the rotation axis 5a and toward the center of the polygon mirror 5. The position where the laser beam is irradiated is a portion of the outer peripheral surface of the polygon mirror 5 where the first reflection surfaces 51 are arranged in the circumferential direction.

For example, referring to fig. 4(a), the laser beam incident on the polygon mirror 5 is incident on the first reflection surface 51, reflected, incident on the second reflection surface 52, reflected again, and then emitted from the polygon mirror 5. When the polygon mirror 5 is rotated in a state where light is applied to any one side of the polygon mirror 5, the directions of the first reflection surface 51 and the second reflection surface 52 are continuously changed, and therefore the direction of light emitted from the second reflection surface 52 is smoothly changed in the direction indicated by the thick arrow. Therefore, the deflection of the emitted light can be realized.

The inclination angle of the first reflection surface 51 or the second reflection surface 52 with respect to a virtual plane perpendicular to the rotation axis 5a is 45 °. Therefore, the light emitted from the polygon mirror 5 is deflected in a virtual plane perpendicular to the rotation axis 5 a. The inclination directions of the first and second reflection surfaces 51 and 52 and the position of the second reflection surface 52 are switched for each side of the polygon mirror 5. As a result, as shown in fig. 4(a) and 4(b), the output position of the output light emitted from the polygonal mirror 5 (in other words, the plane including the range of the deflection angle of the output light) is discontinuously switched in the direction of the rotation axis 5a according to which side of the polygon of the polygonal mirror 5 the laser beam is irradiated. In the state of fig. 4 a, the output position is located on one side (the rear side of fig. 4) in the direction of the rotation axis 5a than the incident position, and in the state of fig. 4 b, the output position is located on the opposite side (the front side of fig. 4) in the direction of the rotation axis 5a than the incident position. In either state, the emitted light is deflected in a virtual plane perpendicular to the rotation axis 5 a.

As shown in fig. 5, the polygon mirror 5 of the present embodiment is configured by combining 2 sections that are bisected in the direction of the rotation axis 5 a. The divided parts are respectively of the same shape. In each divided component, a first reflection surface 51 and a second reflection surface 52 corresponding to each other are arranged on each side of the polygon mirror 5. This facilitates manufacturing. However, there is no limitation on how the polygon mirror 5 is manufactured. For example, the polygon mirror 5 can be formed of one piece.

The second light guide 6 shown in fig. 2 is adapted to reflect the laser beam emitted from the polygon mirror 5 and guide the reflected laser beam toward the surface of the workpiece 10. In the following description, a point at which the laser beam is irradiated onto the workpiece 10 may be referred to as an irradiated point.

The second light guide 6 is configured to reflect the laser beam a plurality of times and guide the laser beam to the surface of the workpiece 10. As shown in fig. 2, the second light guide section 6 includes a first light guide unit 61 and a second light guide unit 62, the first light guide unit 61 has a plurality of mirrors, and the second light guide unit 62 has a plurality of light guide components.

The first light guide unit 61 and the second light guide unit 62 are arranged so that the optical path length until reaching the surface of the workpiece 10 is substantially constant, regardless of the emission position and deflection angle of the laser beam from the polygon mirror 5. Thereby, regardless of the rotational phase of the polygon mirror 5, a state in which the focal point of the laser beam is substantially located near the surface of the workpiece 10 can be maintained.

The function of the second light guide 6 will be described in detail below. Fig. 6 is a schematic diagram illustrating a state where the position of a virtual circular arc, which is a locus on which the focal point moves due to deflection of the laser beam by the rotation of the polygon mirror 5, is converted by the second light guide section 6.

If the second light guide unit 6 is not provided, the focal point of the laser beam emitted from the polygon mirror 5 (a point at a predetermined distance from the laser oscillator 21) draws an arc-shaped trajectory as shown by the dashed-dotted line on the upper side of fig. 6 as the rotation angle of the polygon mirror 5 changes by an angle corresponding to one side. The center of the trajectory is a deflection center C that deflects the laser beam by the polygon mirror 5. The radius of the trajectory corresponds to the optical path length from the deflection center C to the focal point.

As described above, the emission positions of the laser beams emitted from the polygon mirror 5 are switched in 2 stages in the direction of the rotation axis 5a according to which side of the polygon mirror 5 the laser beams are irradiated. Therefore, although the upper arc-shaped locus in fig. 4 appears to be one, actually 2 loci (virtual arcs DA1, DA2) are superimposed.

The second light guide unit 6 converts the positions of the 2 virtual arcs DA1 and DA2 so as to be substantially aligned in the scanning direction on the workpiece 10 by bending the optical path from the deflection center C to the focal point. That is, the positions of the virtual arcs DA1, DA2 are switched by the second light guide 6 so that the directions of the corresponding virtual chords VC1, VC2 substantially coincide with the scanning line L. Thus, the entire assembly of the 2 virtual arcs DA1 and DA2 after the switching position extends substantially linearly so as to cover the length of the scanning line L.

In this way, the first light guide unit 61 and the second light guide unit 62 reflect light a plurality of times so that the chords VC1 and VC2 of the 2 virtual arcs DA1 and DA2 are in the same direction as the scanning direction (arranged in the scanning direction), and the 2 virtual arcs DA1 and DA2 are generated by switching the emission positions of the laser beams emitted from the polygon mirror 5 in 2 stages.

In this way, in order to convert the plurality of virtual arcs DA1 and DA2 to different positions, it is necessary to reflect light in different directions according to the virtual arcs DA1 and DA 2. In this regard, as described above, the position of the laser beam emitted from the polygon mirror 5 changes in the direction of the rotation axis 5a for each of the 2 virtual arcs DA1 and DA 2. Therefore, it is possible to easily avoid mechanical interference of the reflecting mirror, the light guide component, and the like, and to realize a configuration in which light is reflected in different directions for each arc.

The virtual arcs DA1, DA2 are relocated on the scanning line L at 2 points on both ends thereof by the second light guide unit 6, and the virtual arcs DA1, DA2 (i.e., the curves connecting the 2 points) are relocated on the optical axis direction downstream side of the scanning line L. As the polygon mirror 5 rotates, the focal point of the laser beam moves along the arcs DA1, DA2 whose positions are switched in this manner.

If the central angle of the arc is not large, the virtual arcs DA1, DA2 are approximate to the corresponding virtual chords VC1, VC 2. Accordingly, the movement of the focal point along the virtual arcs DA1 and DA2 by the rotation of the polygon mirror 5 can be considered to be substantially equivalent to the constant-velocity linear motion along the scanning line L.

This enables the focal point of the laser beam to be scanned substantially linearly and at a constant speed in the vicinity of the surface of the workpiece 10.

Next, the first light guide unit 61 and the second light guide unit 62 will be described in detail. Fig. 7 is a perspective view showing the polygon mirror 5 and the second light guide 6. Fig. 8 is a schematic diagram illustrating irradiation of laser beams to different irradiation regions by switching the emission positions of the laser beams from the polygon mirror 5. Fig. 9 is a diagram schematically showing an optical path from the polygon mirror 5 to the irradiation of the workpiece 10 by reflecting the laser beam.

As shown in fig. 7 and 8, the first light guide unit 61 includes a first reflecting mirror 61a and a second reflecting mirror 61 b. The second light guide unit 62 includes a first light guide part 62a and a second light guide part 62 b. The first light reflecting portion 71 is composed of a first reflecting mirror 61a and a first light guide part 62 a. The second light reflecting unit 72 includes a second reflecting mirror 61b and a second light guiding member 62 b.

The first reflecting mirror 61a and the second reflecting mirror 61b are provided so as to correspond to 2 emission positions of the light emitted from the polygon mirror 5 in the direction of the rotation axis 5 a. As shown in fig. 7, the first mirror 61a and the second mirror 61b are provided at different positions from each other in the direction of the rotation axis 5a of the polygon mirror 5.

The first reflecting mirror 61a is disposed within an angular range in which the outgoing light is deflected as indicated by the bold arrow in fig. 4(a) so that the light is reflected toward the first light guide part 62 a.

The first light guide part 62a is disposed corresponding to the first reflecting mirror 61 a. The first light guide part 62a reflects the light guided from the first reflecting mirror 61a while shifting it in the direction of the rotation axis 5 a. Although the first light guide part 62a is schematically illustrated in fig. 7, the first light guide part 62a may be formed of, for example, a V-shaped mirror.

The light reflected by the first light guide member 62a is guided along a virtual plane disposed between the first reflecting mirror 61a and the second reflecting mirror 61b, and is irradiated to a portion of the virtual chord VC1 of the workpiece 10. The irradiation region (first scanning region) corresponding to this virtual line VC1 corresponds to the range of the deflection angle of the outgoing light in fig. 4 (a).

The second reflecting mirror 61b is disposed in a range where the outgoing light is deflected as indicated by a thick arrow in fig. 4(b) so that the light is reflected toward the second light guide element 62 b.

The second light guide member 62b is disposed to correspond to the second reflecting mirror 61 b. The second light guide 62b reflects the light guided from the second reflecting mirror 61b while shifting the light in the direction of the rotation axis 5 a. Although the second light guide part 62b is schematically illustrated in fig. 7, the second light guide part 62b may be formed of a V-shaped mirror, for example.

The light reflected by the second light guide member 62b is guided along a virtual plane disposed between the first reflecting mirror 61a and the second reflecting mirror 61b, and is irradiated to a portion of the virtual chord VC2 of the workpiece 10. The irradiation region (second scanning region) corresponding to this virtual line VC2 corresponds to the range of the deflection angle of the outgoing light in fig. 4 (b).

With the above configuration, when the polygon mirror 5 is rotated, the scanning of 2 irradiation regions is alternately repeated at the focal point of the laser beam. Specifically, when light is irradiated to one side of the polygon mirror 5, the light emitted from the polygon mirror 5 is reflected by the first light reflecting section 71, and the irradiation field corresponding to the virtual chord VC1 in fig. 8(a) is scanned. On the other hand, when light is irradiated on an adjacent side, the light emitted from the polygon mirror 5 is reflected by the second light reflecting section 72, and the irradiation field corresponding to the virtual string VC2 in fig. 8(b) is scanned. In fig. 8, the polygon mirror 5 is schematically shown as a triangle focusing only on one side of light reflection. This enables the entire scanning line to be linearly scanned along the long scanning line L.

In the configuration of the present embodiment, by rotating only the polygon mirror 5, the output position of the output light can be switched in the direction of the rotation axis 5a at a timing synchronized with a period in which the deflection angle of the output light changes from one end to the other end of the predetermined angle range. Therefore, by guiding the light emitted from different positions in the direction of the rotation axis 5a to different positions, the irradiation region can be switched at high speed.

In the present embodiment, the irradiation region is switched by changing the emission position of the emitted light discontinuously in the direction of the rotation axis 5 a. Therefore, the range of the deflection angle of the outgoing light corresponding to one side of the polygon mirror 5 can be reduced as compared with the case where the irradiation field is switched by dividing the range of the deflection angle of the outgoing light (in the circumferential direction) and guiding each light to a different portion. That is, the number of sides of the polygon mirror 5 can be increased.

In view of the polygonal prism-shaped polygon mirror, strictly speaking, the distance between the point (reflection point) at which light is reflected by the polygon mirror and the rotation axis of the polygon mirror is not constant. Considering the polygon of the polygon mirror, when light is irradiated to the bisector of each side, the distance between the reflection point and the rotation axis is shortest. The distance between the reflection point and the rotation axis gradually increases as the irradiation point of the light beam approaches the end of the side from the bisector. As such, the position of the reflection point periodically changes with the rotation of the polygon mirror 5.

The position of the reflection point varies depending on the variation in the optical path length. Therefore, scanning distortion is caused particularly when light is irradiated in the vicinity of an end (in other words, a vertex) of a side of a polygon of the polygon mirror.

In this regard, since the polygon mirror 5 of the present embodiment can increase the number of sides as described above, each side can be shortened. As a result, the positional change of the reflection point causing the scan distortion can be reduced. That is, distortion caused by the situation where the laser beam is irradiated to a portion near the vertex (ridge) of the polygon mirror 5 can be reduced.

In the polygon mirror 5 of the present embodiment, the following operations are performed simultaneously by causing the light irradiation point to pass through the vertex of the polygon mirror 5: the deflection angle of the output light is discontinuously shifted from one end to one end of the predetermined angle range, and the emission position of the output light is discontinuously changed in the direction of the rotation axis 5a to switch the irradiation region. This can substantially prevent an increase in the time during which the laser beam cannot be irradiated to the polygon mirror 5.

The following specifically explains the process. The laser beam is not meant to be infinitely thin but has a certain thickness. Therefore, when the laser beam is irradiated to the polygon mirror 5, the irradiation area has a certain area.

Since the polygon mirror 5 rotates, a timing including a vertex (ridge) of the polygon mirror 5 is repeatedly generated within the irradiation area of the laser light. At this timing, since the intensity of the light emitted from the polygon mirror 5 and irradiated on the workpiece 10 is unstable, the work such as machining cannot be performed satisfactorily. Therefore, at this timing, irradiation of the laser beam from the laser oscillator 21 is temporarily interrupted so that the laser beam does not enter the polygon mirror 5.

In the configuration of patent document 1, the range of the deflection angle of the outgoing light on one side of the polygon mirror is divided (in the circumferential direction), and each of the divided light beams is guided to a different irradiation region. In this configuration, since the intensity of light applied to the workpiece 10 is unstable not only at the timing when the vertex of the polygon mirror 5 is included in the irradiation region of the laser beam but also at the timing when the output light approaches the boundary of the divided deflection angle range, it is necessary to block the laser beam in the same manner as described above.

In this regard, in the present embodiment, when the vertex of the polygon mirror 5 passes through the irradiation region of the laser beam, the irradiation region is also switched at the same time. Therefore, the scanning distortion can be reduced without substantially increasing the timing at which the laser beam must be interrupted (the same irradiation rate as in patent document 1).

The diameter of the laser beam irradiated on the polygon mirror 5 is, for example, several millimeters. However, for example, if the laser beam is converged to the order of 1/100mm in the focal point, it may be necessary to set the diameter of the polygon mirror at the time of irradiationIn this way, when the diameter of the laser beam is large, if the side of the polygon mirror 5 is not long enough, the proportion of time for which the laser beam must be blocked may increase. On the other hand, increasing the length of the side of the polygon mirror 5 leads to an increase in the size of the polygon mirror 5. In this sense, the configuration of the present embodiment, which does not increase the timing at which the laser beam must be blocked, is advantageous in that the effective use of the laser beam and the miniaturization of the polygon mirror 5 can be achieved at the same time.

Fig. 9(a) schematically shows an optical path of the laser beam reflected by the polygon mirror 5 and reaching the first reflecting mirror 61a or the second reflecting mirror 61b in the configuration of fig. 7 and 8. Fig. 9(b) schematically shows an optical path of the laser beam reflected by the first reflecting mirror 61a or the second reflecting mirror 61b until the laser beam reaches the workpiece 10 after being reflected by the first light guide part 62a or the second light guide part 62 b.

As shown in fig. 9(a), the emission positions P1 and P2 of the laser beam emitted from the polygon mirror 5 are switched in the direction of the rotation axis 5a so as to be symmetrical with respect to the incident position Q1 of the laser beam on the polygon mirror 5. In other words, when considered in the direction of the rotation axis 5a, the distance from one exit position P1 to the incident position Q1 is equal to the distance from the other exit position P2 to the incident position Q1. Thus, by symmetrically configuring the first light guide unit 61 and the second light guide unit 62, even when the emission positions P1, P2 of the laser beams are switched in the direction of the rotation axis 5a, it is easy to keep the optical path length until reaching the optical path of the workpiece 10 substantially constant. Therefore, a simple configuration can realize scanning with less distortion.

As described above, the polygon mirror 5 of the present embodiment rotates about the rotation axis 5 a. The first reflection surface 51 and the second reflection surface 52 are disposed on 2 or more sides among the plurality of sides of the polygon mirror 5. The first reflecting surface 51 is formed in a planar shape inclined with respect to a virtual plane perpendicular to the rotation axis 5 a. The second reflecting surface 52 is formed in a planar shape inclined with respect to a virtual plane perpendicular to the rotation axis 5 a. The light incident on the polygon mirror 5 is reflected by the first reflection surface 51 and then reflected by the second reflection surface 52. The first reflecting surface 51 is inclined in a different direction with respect to a virtual plane perpendicular to the rotation axis 5a among the plurality of sides.

Thereby, the position (emission position) of the light emitted from the polygon mirror 5 is discontinuously switched in the direction of the rotation axis 5a according to the rotation of the polygon mirror 5. Therefore, by guiding the emitted light to different scanning regions according to the emission position in the direction of the rotation axis 5a, it is possible to scan a plurality of regions while switching the scanning regions at high speed. In contrast, the number of sides of the polygon mirror 5 can be increased, and a configuration for scanning a plurality of areas can be easily realized. This can shorten the sides of the polygon mirror 5, and thus can reduce scanning distortion at both ends of each scanning area.

In the polygon mirror 5 of the present embodiment, 2 sides opposite to the direction in which the first reflection surface 51 is inclined are included among the plurality of sides, and the first reflection surface 51 is inclined with respect to a virtual plane perpendicular to the rotation axis 5 a. The distance between the first reflection surface 51 and the second reflection surface 52 in the direction of the rotation axis 5a is equal between one side and the other side of the 2 sides.

Therefore, by providing the configuration in which the emitted light is guided to the respective scanning regions symmetrically, even if the emission position from the polygon mirror 5 is switched in the direction of the rotation axis 5a, the change in the optical path length can be reduced. Therefore, high-quality scanning can be achieved.

The light guide device 22 according to the present embodiment includes the polygon mirror 5, the first light reflecting section 71, and the second light reflecting section 72. As shown in fig. 8(a), the first light reflecting section 71 guides the light deflected on one of the sides of the polygon mirror 5 to the scanning region corresponding to the virtual chord VC 1. As shown in fig. 8(b), the second light reflecting part 72 guides the light deflected on the other side of the polygon mirror 5 toward the scanning area corresponding to the virtual chord VC 2.

Therefore, by guiding light to a plurality of scanning areas, various kinds of parts can be flexibly scanned. Since the scanning distortion in each scanning area is reduced, high-quality scanning can be performed as a whole.

The laser processing apparatus 100 of the present embodiment includes a light guide device 22. The first light reflecting portion 71 and the second light reflecting portion 72 each include a plurality of reflecting surfaces that reflect light. The first light reflecting unit 71 and the second light reflecting unit 72 reflect the light emitted from the rotating polygon mirror 5a plurality of times and guide the light to an arbitrary irradiation point included in the linear scanning line L. The optical path length from the incident position of the light on the polygon mirror 5 to the irradiated point is substantially constant at all the irradiated points on the scanning line L. The scanning speed on the scanning line L is substantially constant by the light guided from the polygon mirror 5 by the first light reflector 71 and the second light reflector 72.

Therefore, by scanning while switching the plurality of scanning regions, the entire linear scanning can be performed over a long distance. Incidentally, when the rotational phase of the polygon mirror is a rotational phase in which the irradiation range of the incident light covers a portion corresponding to the vertex of the polygon, the light intensity of the reflected light is unstable and cannot be practically used for light scanning. Further, in the case of a configuration in which the deflection angle range of the outgoing light corresponding to one side of the polygon mirror is divided and guided to different scanning regions, the same cannot be applied to the optical scanning when the angle of the outgoing light approaches the rotational phase of the divided boundary. In this regard, in the configuration of the present embodiment, the rotational phase of the polygon mirror 5 in which incident light is irradiated to the polygon vertex and the rotational phase of the polygon mirror 5 corresponding to the switching of the irradiation region can be made to be the common phase. Accordingly, the range of the rotational phase of the polygon mirror that cannot be used for optical scanning is not increased, and therefore, the scanning of light can be effectively used, and scanning with less distortion can be realized.

Next, a plurality of modifications of the polygon mirror 5 will be described. In the following description of the present modification, the same reference numerals as in the drawings are given to the same or similar members as those of the above-described embodiment, and the description thereof will be omitted.

The polygon mirror 5x of the first modification shown in fig. 10 is configured as a regular dodecagon when viewed from the direction of the rotation axis 5 a. A first reflection surface 51 and a second reflection surface 52 are disposed on each side. In the polygon mirror 5x of the present modification, the direction in which the first reflecting surface 51 is inclined with respect to the virtual plane perpendicular to the rotation axis 5a is the same on all sides. The direction of inclination of the second reflecting surface 52 with respect to a virtual plane perpendicular to the rotation axis 5a is also the same on all sides. The positions where the second reflecting surfaces 52 are provided in any 2 of the circumferentially adjacent sides are different from each other in the direction of the rotation axis 5 a. Therefore, the distance between the first reflection surface 51 and the second reflection surface 52 in the direction of the rotation axis 5a is different between the adjacent 2 sides.

In the present modification, the laser beam incident on the polygon mirror 5x is first reflected by the first reflecting surface 51, then reflected by the second reflecting surface 52, and then emitted from the polygon mirror 5 x. The emission position from which the laser beam is emitted from the polygon mirror 5x is switched in 2 stages in the direction of the rotation axis 5a according to which side of the polygon mirror 5x the laser beam is irradiated.

Unlike the polygon mirror 5 of fig. 3, the polygon mirror 5x of the present modification has an asymmetric relationship between the 2 emission positions and the incident position. Therefore, in the polygon mirror 5x of the present modification, the optical path length from the time of incidence on the polygon mirror 5x to the time of emission slightly changes according to the switching of the emission position. However, by appropriately adjusting the position of the reflecting mirror or the like of the second light guide 6, the difference in the optical path length can be canceled out.

As described above, in the polygon mirror 5x of the present modification, 2 sides having the same direction in which the first reflection surface 51 is inclined are included among the plurality of sides of the polygon mirror 5x, and the first reflection surface 51 is inclined with respect to the virtual plane perpendicular to the rotation axis 5 a. The distance between the first reflecting surface 51 and the second reflecting surface 52 is different between one side and the other side of 2 sides adjacent in the circumferential direction.

This makes it possible to switch the positions at which the laser beams are emitted from the polygon mirror 5x with a simple configuration.

The polygon mirror 5y of the second modification shown in fig. 11 is configured as a regular thirty-two polygon when viewed from the direction of the rotation axis 5 a. In the polygon mirror 5y of the present modification, the output position of the laser beam can be switched in four stages in the direction of the rotation axis 5a by combining the switching of the tilt direction of the first reflecting surface 51 on the polygon mirror 5 of fig. 3 and the switching of the distance between the first reflecting surface 51 and the second reflecting surface 52 on the polygon mirror 5x of fig. 10. The output position of the laser beam is cyclically switched between 4 positions in accordance with the rotation of the polygon mirror 5 y.

In the case of using this polygon mirror 5y, as shown in fig. 12, the second light guide section 6 can be configured to guide the outgoing light deflected at the 4 outgoing positions to the corresponding 4 irradiation areas. Therefore, the first light guiding unit 61 includes a first reflecting mirror 61a, a second reflecting mirror 61b, a third reflecting mirror 61c, and a fourth reflecting mirror 61 d. The second light guide unit 62 includes a first light guide part 62a, a second light guide part 62b, a third light guide part 62c, and a fourth light guide part 62 d.

Next, a modification of the second light guide unit 6 will be described.

The second light guide 6 may be configured to divide each deflection angle range (in other words, virtual arcs DA1 and DA2) corresponding to one side of the polygon mirror 5 in the circumferential direction and to arrange the divided arcs on the scanning line L. Fig. 13 shows a structure of this modification.

In the modification of fig. 13, the range of the deflection angle of the outgoing light is divided into two for each of 2 outgoing positions in the direction of the rotation axis 5 a. This division can be achieved by arranging a mirror or the like so as to correspond to only a part of the deflection range of the laser beam. Thus, the laser beam is guided to the total of 4 irradiation regions (and the virtual chord)The corresponding irradiation zone).

By dividing the virtual arcs shorter, each arc can be made to better approximate a straight line. Therefore, distortion of scanning can be reduced.

While the preferred embodiment and the modified examples of the present invention have been described above, the above configuration can be modified as follows, for example.

The number of polygon sides of the polygon mirrors 5, 5x, and 5y can be changed arbitrarily.

The emission positions of the light from the polygon mirrors 5, 5x, 5y may be changed so as to be switched in three stages, eight stages, or the like, for example, without two stages or four stages.

The first reflection surface 51 and the second reflection surface 52 may be implemented by using prisms. Similarly, the second light guide part 62b can also be implemented using a prism.

The work conveying apparatus 1 can be omitted. That is, the laser processing can be performed on the fixed workpiece 10 while adjusting the position of the laser unit 2.

The polygon mirrors 5, 5x, and 5y can be used for optical scanning other than laser processing.

Description of the reference numerals

5. 5x, 5y polygon mirror

5a rotating shaft

6 second light guide part

22 light guide device

51 first reflecting surface

52 second reflecting surface

71 first light reflecting part

72 second light reflecting part

100 laser processing apparatus (optical scanning apparatus).