Light reflection device

Abstract

To provide a light reflection device with reduced flatness deterioration of a reflection surface.SOLUTION: The light reflection device comprises: a reflection member including a reflection surface reflecting incident light and a rear surface facing the reflection surface and provided with a plurality of fitting holes; a connection member screw-engaged with each of the plurality of fitting holes; and a piezoelectric element propagating extension / contraction force via the connection member to the reflection member. The light reflection device inclines the reflection member by extending and contracting the piezoelectric element. On positions corresponding to the plurality of fitting holes in a side face of the reflection member, a space part shaped to include the fitting holes is provided in plane view of the reflection member.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a light reflecting device used, for example, in a laser processing device, for reflecting a laser beam emitted from a laser oscillator in order to irradiate a given position on a workpiece with the laser beam. [Background technology]

[0002] A conventional light reflecting device is known that has a configuration in which a single mirror (reflecting member) for reflecting laser light is driven by a plurality of piezoelectric elements connected to the rear surface of the mirror and spaced apart from each other, as shown in, for example, Fig. 4 of Patent Document 1. This type of light reflecting device controls the voltage applied to the piezoelectric elements to expand and contract each of the piezoelectric elements, thereby tilting the reflecting member at an arbitrary angle and reflecting the incident laser in an arbitrary direction.

[0003] Here, in a conventional light reflecting device of this type, as shown in FIG. 1, there is a configuration in which bolts 104 are screwed into a plurality of screw holes (mounting holes) 103 provided on a back surface 106 opposite to a reflecting surface 102 of a reflecting member 101, and these bolts 104 and piezoelectric element 105 are fixed with an adhesive or the like, and the device is held by a base 107. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 08-320441 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the bolt 104 is screwed into the mounting hole 103, the axial force of the bolt 104 causes distortion around the mounting hole 103, which causes a problem of deteriorating the flatness of the reflecting surface 102. As shown in FIG. 2, the amount of distortion of the reflecting surface 102 is large near the mounting hole 103, which is the source of the distortion. In recent years, there has been a demand for lighter reflecting members in order to further increase the driving speed of the light reflecting device, and thinning the reflecting member to reduce its weight has been considered. However, making the reflecting member thinner can cause more distortion of the reflecting surface, and it is therefore necessary to reduce this distortion. In order to reduce the distortion of the reflecting surface, it is possible to reduce the tightening torque of the bolt, but this is not appropriate because weakening the tightening torque may cause the bolt to become more likely to come off during repeated high-speed driving.

[0006] SUMMARY OF THE PRESENT DISCLOSURE An object of the present invention is to provide a light reflecting device which solves the above-mentioned problems and reduces the deterioration of the flatness of the reflecting surface. [Means for solving the problem]

[0007] In order to solve the above-mentioned problems in the conventional art, the present invention provides a light reflecting device comprising a reflecting member having a reflecting surface that reflects incident light and a back surface facing the reflecting surface and having a plurality of mounting holes provided therein, a connecting member that is screwed into each of the plurality of mounting holes, and a piezoelectric element that transmits an expansion and contraction force to the reflecting member via the connecting member, and in which the reflecting member is tilted by expanding and contracting the piezoelectric element, wherein at each position corresponding to the plurality of mounting holes on the side of the reflecting member, a space portion having a shape that includes each of the mounting holes when viewed in a plane of the reflecting member is provided. Effect of the Invention

[0008] According to the present invention, it is possible to provide a light reflecting device in which deterioration of the flatness of the reflecting surface is reduced. [Brief description of the drawings]

[0009] [Figure 1] 13A and 13B are diagrams illustrating a connection configuration between a reflecting member and a piezoelectric element of a conventional light reflecting device. [Diagram 2] 1A and 1B are diagrams illustrating the distribution of distortion amounts occurring on a reflecting surface. [Diagram 3] 1 is a schematic plan view of a light reflecting device according to an embodiment of the present invention; [Figure 4] 4 is a cross-sectional view taken along the line AA in FIG. [Diagram 5] 4A to 4C are diagrams illustrating a light reflecting member in one embodiment of the present invention. [Figure 6] 11A to 11C are diagrams illustrating modified examples of the cutout portion in the embodiment of the present invention. [Figure 7] FIG. 4 is a schematic block diagram of a control system of the light reflecting device according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Representative embodiments of the present invention will be described below with reference to the drawings. Fig. 3 is a schematic plan view of a light reflecting device according to one embodiment of the present invention, Fig. 4 is a cross-sectional view taken along the line AA in Fig. 3, and Fig. 5 is a diagram illustrating a light reflecting member according to one embodiment of the present invention.

[0011] In the figure, 1 is a light reflecting device, 2 is a roughly cylindrical pedestal that forms the base of the light reflecting device, and inside pedestal 2 is formed a circular piezoelectric element housing section 3 that houses a piezoelectric element. 4a-c are piezoelectric elements that expand and contract in the length direction (up and down on the paper surface of FIG. 4) when a voltage is applied, and the amount of expansion and contraction is approximately proportional to the applied voltage. In piezoelectric element housing section 3, three piezoelectric elements 4a-c are arranged at equal intervals from each other on a circumference of a predetermined radius R that is concentric with the center of piezoelectric element housing section 3, and are fixed upright to pedestal 2.

[0012] Reference numeral 5 denotes a disk-shaped reflecting member. The reflecting member 5 is made of, for example, a beryllium metal material, and the reflecting surface 5a that reflects the incident laser is mirror-finished. On the back surface 5b opposite the reflecting surface 5a, three mounting holes 6a to 6c, the same as the number of piezoelectric elements, are provided at equal intervals on a circumference of a radius r that is concentric with the outer circumference of the reflecting member 5. The radius r and the radius R are the same value. A thread is engraved on the inner wall of each of the mounting holes 6a to 6c for threaded engagement with the bolts 8a to 8c, which are connecting members.

[0013] The spaces 7a to c are notched spaces provided at positions corresponding to the mounting holes 6a to c on the side surface of the reflecting member 5. As shown in FIG. 3 and FIG. 5(a), the spaces 7a to c are shaped as if they are surrounded by arcs of a predetermined radius having their centers on the straight lines connecting the center of the reflecting member 5 and the centers of the mounting holes 6a to c in a plan view of the reflecting member 5, and are formed at positions that include each mounting hole within each arc. Furthermore, as shown in FIG. 4 and FIG. 5(b), the spaces 7a to c are connected to the mounting holes 6a to c in a side view of the reflecting member 5, respectively, and the mounting holes are not formed on the reflecting surface 5a side through the spaces 7a to c. Such notched spaces can be formed, for example, by cutting the side surface of the reflecting member with a disk-shaped rotary cutting tool. In this embodiment, the positions corresponding to the mounting holes refer to the vicinity of the positions closest to each mounting hole on the side surface of the reflecting member.

[0014] In this embodiment, as shown in Fig. 3 to Fig. 5, the spaces 7a to 7c are sized so that they do not communicate with each other. By making the spaces larger, the distortion of the reflecting surface can be reduced, but if the spaces are made large enough to communicate with each other, the rigidity of the reflecting member itself during high-speed driving decreases. Therefore, in order to prevent the rigidity from decreasing too much, it is desirable to make the spaces large enough so that they do not communicate with each other, as in this embodiment.

[0015] Reference numerals 8a to c denote bolts serving as connecting members for connecting the reflecting member 5 and the piezoelectric elements 4a to c. One end of the bolts 8a to c is provided with a thread that thread-engages with the mounting holes 6a to c, and the other end is flat so as to be bonded to the top of the piezoelectric elements 4a to c. The end of the bolts 8a to c on the side where the thread is provided is fixed to the mounting holes 6a to c of the reflecting member 5 by thread engagement, and the flat end is fixed to the top of the piezoelectric elements 4a to c by an adhesive or the like. In this embodiment, the piezoelectric elements and the bolts are fixed with an adhesive or the like, but as long as the expansion and contraction force of the piezoelectric elements is transmitted to the reflecting member via the bolts, they do not need to be fixed by adhesion.

[0016] As described above, the reflecting member of the present invention has a space between the mounting hole, which is the source of distortion on the reflecting surface, and the reflecting surface. In other words, the physical connection between the mounting hole and the position on the reflecting surface facing the mounting hole (the position where the amount of distortion on the reflecting surface is large when there is no space) is cut off at the shortest distance between the two. This reduces the amount of distortion on the reflecting surface and suppresses deterioration of flatness.

[0017] In this embodiment, the space portions 7a to c are notches having a circular arc shape in plan view. However, in the present invention, as long as a space portion is provided between the reflecting surface and the mounting hole that is the source of distortion occurring on the reflecting surface, the shape of the space portion is not limited to this. Therefore, for example, as shown in FIG. 6, the side hole shape may be a substantially rectangular shape extending from the side surface to the center of the reflecting member 5 on a straight line connecting the center of the reflecting member 5 and the center of each of the mounting holes 6a to c in a plan view of the reflecting member 5, and including each mounting hole. In addition, such a side hole can be formed, for example, by drilling a hole from the side surface of the reflecting member with a drill having the same diameter as or larger than the mounting holes.

[0018] Fig. 7 is a schematic block diagram of a control system of an optical reflector in one embodiment of the present invention. The control and operation of the optical reflector in one embodiment of the present invention will be described with reference to Fig. 7. In Fig. 7, reference numeral 10 denotes a reflector control unit that controls the reflecting member 5 to tilt at a desired angle by adjusting the voltage applied to each of the piezoelectric elements 4a-c. The reflector control unit 10 includes piezoelectric element drive circuits 11a-c that are connected to the piezoelectric elements 4a-c, respectively, and apply a predetermined voltage to each of the piezoelectric elements.

[0019] In such a configuration, the light reflecting device 1 of the present invention tilts the reflecting member 5 at any angle by adjusting the voltage applied by the reflecting device control unit 10 to each of the piezoelectric elements 4a-c, thereby expanding and contracting each piezoelectric element and changing the height of the reflecting member at each position where the reflecting member and the piezoelectric element are connected.

[0020] More specifically, for example, when the light reflection device 1 is used in a laser processing device, the reflection device control unit 10 changes the voltage applied to each piezoelectric element based on the laser irradiation position information provided from a higher-level control unit (not shown), and tilts the reflection member 5 to an arbitrary angle. That is, the reflection member 5 is tilted to an angle at which the laser L incident on the reflection member 5 is incident on the laser irradiation position on the workpiece (not shown). Note that, regarding a control method for tilting the reflection member 5 to an arbitrary angle (that is, for tilting to an angle at which the reflected laser light is incident on an arbitrary position on the workpiece), a known method such as that described in JP 2018-185352 A can be used. This publication discloses a control method for expanding and contracting three piezoelectric elements arranged on the back surface of the reflection member, as in this embodiment, to tilt the reflection member to an arbitrary angle (to tilt to an angle at which the reflected laser is incident on an arbitrary position).

[0021] As described above, in the present invention, the space is provided at the shortest distance between the mounting hole and the position on the reflecting surface facing the mounting hole position (the position where the amount of distortion of the reflecting surface is large when there is no space), and the physical connection between the two is cut off at that position. This reduces the transmission of distortion caused by the axial force of the bolt, which is the connecting member, to the reflecting surface, and reduces the deterioration of the flatness of the reflecting surface. In addition, the present invention contributes to increasing the driving speed of the reflecting device because the reflecting member is made lighter by providing the space. Furthermore, in the present invention, the size of each space is such that they do not communicate with each other, thereby suppressing the decrease in rigidity of the reflecting member. This stabilizes the mechanical characteristics of the light reflecting device when it is driven at high speed, and improves the processing quality of the laser processing device using it. [Explanation of symbols]

[0022] 1: light reflecting device, 2: base, 3: piezoelectric element housing, 4a-c: piezoelectric element, 5: reflecting member, 5a: reflecting surface, 5b: back surface, 6a-c: mounting holes, 7a-c: space, 8a-c: bolts (connecting members), 10: light reflecting device control section, 11a-c: piezoelectric element driving circuit

Claims

1. a reflecting member including a reflecting surface that reflects incident light and a back surface facing the reflecting surface and having a plurality of mounting holes; a connecting member that is threadably engaged with each of the plurality of mounting holes; a piezoelectric element that transmits an expansion and contraction force to the reflecting member via the connecting member, In a light reflection device in which the piezoelectric element is expanded and contracted to tilt the reflection member, A space portion having a shape including each of the mounting holes in a plan view of the reflecting member is provided at each of the positions corresponding to the plurality of mounting holes on the side surface of the reflecting member. A light reflecting device characterized by:

2. The spaces are provided so as not to communicate with each other.

2. The light reflecting device according to claim 1.

3. A reflecting device control unit that controls the inclination of the reflecting member by driving each of the piezoelectric elements so that the light incident on the reflecting member is reflected to an arbitrary position.

3. The light reflecting device according to claim 1 or 2.

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