JP2000071089A - Optical system driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical system driving device for realizing the precise optical system movement and speed-up (shortening) of the acceleration/ deceleration time. SOLUTION: An X-Y table accommodates a light condensing lens 16, and is guided so as to move on two dimensional plane relatively against a base plate 10. An X axial drive system is equipped with an X linear motor which includes a pair of permanent magnets 23 fixed on the base plate side, and an X motor coil 21 being fixed on the X-Y table side, placed between one pair of the permanent magnets, and movable in an X axial direction on the two dimensional plane by interaction between the magnetic flux and the current from the permanent magnets. A Y axial drive system is similarly equipped with one pair of the permanent magnets fixed on the base plate side, and a Y motor coil which is fixed on the X-Y table side, placed between one pair of the permanent magnets, and movable in a Y axial direction on the two dimensional plane by interaction between the magnetic flux and the current from the permanent magnets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system driving device for moving a table member on which an optical system is mounted in a two-dimensional plane relative to a fixed base, and more particularly to a laser processing device. The present invention relates to an optical system driving device suitable for performing laser processing by moving a laser irradiation nozzle and a table accommodating a condenser lens in a two-dimensional plane.

[0002]

2. Description of the Related Art In order to perform fine processing such as cutting or drilling with a laser beam, it is necessary to scan a laser beam condensing point condensed on the surface of an object with high precision. The scanning speed is determined by processing conditions such as the material and thickness of the processing target and the power of the laser light source.

[0003] In recent years, the scanning speed has tended to be higher due to the demand for higher power of laser light sources and higher production speed.
The irradiation nozzle containing the condenser lens is required to have a high-speed and high-accuracy trajectory generation capability. In order to meet such a demand, the present inventors have proposed an optical system driving device called a trepanning head (Japanese Patent Laid-Open No. 7-9178).

[0004] The trepanning head will be described with reference to FIGS.

FIG. 8 schematically shows a main part of the trepanning head. The condenser lens 81 is held by a structure 82. The structure 82 is held by a fixed base 80 via a structure 83 and couplings 84 and 85 so as to be movable in a two-dimensional direction. The structure 82 includes a core 90.
A coil 91 wrapped around is fixed, and a permanent magnet 92 is arranged to face the coil 91. Permanent magnet 92
Is mounted on a yoke 93 fixed to a fixed base 80. The position of the structure 82 is determined by displacement sensors 95a, 95
b is monitored in two axial directions.

When a controlled current is applied to the coil 91, a two-dimensional driving force acts on the coil 91 to drive the structure 82 in a two-dimensional plane. Although the structure in which the coil 91 is provided on the structure 82 holding the condenser lens 81 has been described, a permanent magnet is fixed to the structure 82 so that the structure is movable.
A coil fixed to the fixed base 80 so as to be opposed may be arranged. A return force for returning the structure 82 to the reference position can also be applied.

FIG. 9 schematically shows the principle of scanning the focal point 101 of the laser beam 100 by driving the condenser lens 81. When the laser beam 100 enters from an eccentric position with respect to the optical axis Ox of the condenser lens 81, the focal point 101 of the laser beam 100 moves with respect to the optical axis Ox.
Located on the opposite side. The condenser lens 81 is
When rotated around the zero axis, the condensing point 101 performs a circular motion. By such an operation, a minute circular opening or via hole can be formed in the object to be processed.

As described above, in order to drive the condenser lens 81 on a circular orbit, the structure 82 includes a combination of the coil 91 and the permanent magnet 92, and is provided with electromagnetic driving means for generating thrust in two directions. Have been.

FIG. 10 is a schematic diagram for explaining the function of the electromagnetic driving means. In FIG. 10, a plurality of permanent magnets 92 are arranged on a yoke 93. Permanent magnet 9
The two magnetic poles are oriented vertically in FIG. 10, and the poles on the upper surface are arranged so as to alternate with N pole, S pole, N pole, and S pole.

A coil 91 wound around a core 90 is disposed above the permanent magnet 92. The coil 91 is divided and arranged corresponding to each permanent magnet 92. Here, the width of one unit of the coil 91 is made smaller than the width of one unit of the permanent magnet 92 so that a uniform force can be exerted within the stroke range in which the coil 91 is driven.

As shown in FIG. 11, a line of magnetic force B emitted from the permanent magnet 92 intersects with the lower winding of the coil 91. When a current i as shown in FIG.
An electromagnetic force based on Fleming's law generates a force in the coil 91 in a direction perpendicular to the drawing.

[0012] As shown in FIG.
2 from the north pole to the south pole of the adjacent permanent magnet 92. When a current in the opposite direction is supplied to the adjacent coil 91, the reversal of the direction of the magnetic force lines incident on the adjacent coil 91 cancels out, and a thrust is generated in the same direction.

If a magnetic material is used for the core 90, the permanent magnet 9
The magnetic field lines emanating from 2 pass through the lower winding of the coil 91, enter the core 90, travel toward the adjacent permanent magnet 92, and hardly reach the upper winding of the coil 91. Therefore, by alternately reversing the magnetic poles of the permanent magnet 92 and supplying a current in the opposite direction to the adjacent coil 91, a thrust can be generated in a direction parallel to the plane of FIG. However, the use of a magnetic material for the core 90 is not an essential requirement and may be a non-magnetic material.

When a magnetic field line crosses the upper and lower windings of the coil 91, a force in the opposite direction is generated, but the distribution of the magnetic field lines is dense below the coil 91 and coarse above the coil 91. Therefore, as a whole, a thrust is generated in the direction of the force generated in the lower winding of the coil 91.

An electromagnetic drive means for driving in the X-axis direction and an electromagnetic drive means for driving in the Y-axis direction are provided in the XY plane in which the structure 82 is movable. It can be carried out.

Referring to FIG. 12, the working principle of the trepanning head will be described. The processing principle is that the entirety of the gas nozzle 200 containing the condensing lens 81 is moved in a two-dimensional plane using the above-described trepanning head, so that the condensing point (focal point) P of the laser beam 100 is scanned and cut. I do. Here, it is important that the direction and the flow rate of the assist gas supplied from the assist gas nozzle 201 to the cutting portion are constant as factors that determine the accuracy of the cutting process using the laser beam. Therefore, in this example, the entire gas nozzle 200 is driven.

[0017]

The problems of the trepanning head will be described below.

1) In the above-mentioned electromagnetic driving means, as shown in FIG. 10, the gap of the magnetic circuit of the thrust generating portion is large, and the magnetic resistance is large, so that the magnetic flux density in the thrust generating portion of the coil 91 is large. Is small. Therefore, the thrust constant (N / A) of the thrust generating portion is small, the ratio of generated thrust / mass of the movable portion (acceleration) is small, and the acceleration / deceleration capability is low.

2) Referring to FIG. 13 as well, one of the factors that determine the movement accuracy is a displacement sensor 9 for feedback.
5a (95b) and the mounting accuracy of the sensor target 110. In the former arrangement of the displacement sensors 95a (95b), the error due to the pitching motion generated in the guide system 111 is the difference between the Abbe error e due to the vertical distance L between the displacement sensor 95a (95b) and the focal point P. Cause. That is, the control target point while a converging point P, the guide system 111 to generate a pitching error theta _P, the focal point P in the Abbe error e (= L · sinθ _P) occurs. Further, since the orthogonality of the X-axis and the Y-axis depends on the orthogonality of the X-axis and the Y-axis at the time of mounting between the respective sensor targets, it is governed by the processing accuracy of the component and the processing accuracy of the mounting reference plane. For this reason, there is a limit to the movement accuracy.

For the reasons described above, there has been a limit to the speed and accuracy of the movement of the above-mentioned trepanning head in response to recent needs.

An object of the present invention is to increase the precision of the movement of the optical system and to increase (decrease) the acceleration / deceleration time.

[0022]

An optical system driving device according to the present invention has an optical system mounted thereon, and a table member guided to move in a two-dimensional plane relative to a fixed base; At least one pair of X-axis permanent magnets fixed to the base so that the magnetic pole faces face each other, and fixed to the table member, between the at least one pair of X-axis permanent magnets, and An X-axis drive system including an X-axis coil movable in the X-axis direction in the two-dimensional plane due to the interaction between the magnetic flux and the current; and at least one pair fixed to the fixed base so that the magnetic pole faces face each other. And the Y-axis permanent magnet is fixed to the table member, and is located between the at least one pair of Y-axis permanent magnets. Characterized in that a Y-axis drive system comprising and Y-axis direction to the movable Y-axis coil.

Each of the X-axis drive system and the Y-axis drive system has a substantially E-shaped yoke member fixed to the fixed base, and the same magnetic pole faces are respectively provided inside both outer legs. It is preferable that a permanent magnet is fixed so as to be opposed, and a central leg portion penetrates the coil, thereby forming a voice coil type linear motor.

It is desirable that the extension length of the coil in the moving direction is longer than the extension length of the permanent magnet in the same direction as the moving direction by the stroke of the coil.

The voice coil type linear motor for the X axis and the voice coil type linear motor for the Y axis are each disposed at a position where the thrust acting on each coil is directed toward the center of gravity of the movable portion including the table member. Is desirable.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. The whole is base plate 1
0, 2 sets (X-axis, Y-axis) of cross roller guides 11, 1
XY table guided by 2, drive system 2
It is composed of a set (X axis, Y axis) of linear motors 20, 30.

To explain the structure from the side of the machining head 13 which is a fixed structure, an intermediate stage 14 on which a linear motion is guided by a Y-axis cross roller guide 12 is provided on a base plate 10. On the intermediate stage 14, a center table 15, which is guided by the X-axis cross roller guide 11 in a direction perpendicular to the Y-axis cross roller guide 12, is guided. This constitutes an XY table.

Next, a gas nozzle 17 including a condenser lens 16 is fixed to the center table 15. The XY table including the gas nozzle 17 is a center table 1
X linear motors 20 and Y arranged in an L-shape
Driven by the linear motor 30. The linear motor used in the present embodiment employs a so-called voice coil motor using a moving coil, and is fastened to the center table 15 such that the center axes of the X motor coil 21 and the Y motor coil 31 are orthogonal to each other. I have.

Next, referring to FIG.
Will be described. This X linear motor 20
An E-shaped yoke 22, a pair of permanent magnets 23 fixed inside both outer legs of the yoke 21, and an X motor coil 21 provided on a central leg of the yoke 21. The pair of permanent magnets 23 are arranged so that their magnetic pole faces face each other, and the X motor coil 21 is arranged between them so as to be movable in the direction of the central axis.

The magnetic circuit formed by the yoke 22 and the pair of permanent magnets 23 is formed as shown by a broken line in FIG. The X motor coil 21 to be driven is a hollow coil bobbin 2
4, the magnetic flux of the upper permanent magnet 23 acts on the upper winding part in the figure, and the magnetic flux of the lower permanent magnet 23 acts on the lower winding part in the figure. When a current is applied to the X motor coil 21 in the direction applied to the windings, a force is generated in the same direction in the upper winding part in the figure and the lower winding part in the figure. A thrust F is generated in the middle X direction. This structure is exactly the same in the case of the Y linear motor 30, so that the description is omitted.

FIG. 4 is a top view of the X linear motor 20 shown in FIG. The X motor coil 21 of the X linear motor 20 is
It is fixed to a center table 15 that moves on an XY plane. For this reason, the extension length in the moving direction is set to the dimension obtained by adding the movable stroke to the dimension of the permanent magnet 23 in the thrust generation direction (X direction). The same applies to the Y motor coil 31, and the extension length in the moving direction is the dimension obtained by adding the movable stroke to the dimension of the permanent magnet 23 in the thrust generation direction (Y direction).

As shown in FIG. 1, the position of the XY table can be detected by simultaneously measuring two orthogonal axes on the XY plane.
This is performed by the -Y linear encoder 18. In the present embodiment, the center table 15 to which the gas nozzle 17 is fixed
The glass scale 19 which is a part of the XY linear encoder 18 is fixed to the end surface of the linear motor, and the sensor head is arranged on the stator of the linear motor. Therefore, the configuration is such that a cable for sensing is not required on the movable section side.
Since this type of XY linear encoder 18 is well known, detailed description is omitted.

In FIG. 1, the present apparatus and gas nozzle 17
Inside, a through hole is formed so that the optical path of the laser beam 100 can be secured at any position within the movable stroke range.

In FIG. 1, the movable part is an XY table,
The gas nozzle 17, the X motor coil 21, and the Y motor coil 31. These movable parts are guided in translation in the X-axis direction by an X-axis cross roller guide 11, and are guided in translation (Y-axis direction) perpendicular to the translation direction by a Y-axis cross roller guide 12. As a result, it is guided on a two-dimensional plane, that is, an XY plane, while restricting the rotational movement in the yaw direction.

Referring to FIG. 3, the thrust in the X-axis direction for driving the movable portion will be described. As described above, the magnetic circuit shown by the broken line causes the magnetic flux flowing downward in the upper gap 26 and the current flowing in the upper winding of the X motor coil 21 to framing left (or right) in the figure. Generates electromagnetic force according to the law In the lower gap 27, the direction of the magnetic flux is upward in the figure, but the X motor coil 2
The direction of the current flowing through the lower winding in FIG. 1 is also reversed, so that a thrust is generated in the same direction as the upper gap 26. X
The configuration in which thrust is generated on both upper and lower surfaces of the motor coil 21 makes it possible to generate a thrust constant (N /
A) can be increased.

Also, in order to reduce the magnetic resistance in the magnetic circuit, the yoke 22 is shaped as shown in FIG. 3 to increase the magnetic flux density in the gap of the thrust generating portion. Similarly, the thrust in the Y-axis direction is obtained by another set of Y linear motors 30 arranged so as to be orthogonal to the X-axis direction. In particular, as described with reference to FIG. 4, the area facing the permanent magnet 23 of the X motor coil 21 or the Y motor coil 31 is changed so that a uniform thrust (conducting current is constant) can be generated over the entire stroke. 2
The size is obtained by adding the stroke in the plane (the X-axis direction and the Y-axis direction) to the area of No. 3. Further, the X motor coil 21 and the Y motor coil 31 are directly attached to the center table 15. Thereby, the gas nozzle 17 as the driven portion can be directly driven in both the X-axis direction and the Y-axis direction.

Further, the relationship between the current supplied to the linear motor shown in FIG. 5 and the generated thrust can be obtained at an arbitrary position.

As described above, an arbitrary movement can be performed by applying an arbitrary thrust vector F (X axis, Y axis) to the movable portion by each linear motor. Further, a driving method without backlash can be provided by using a linear motor capable of directly applying a thrust to a movable portion.

FIG. 6 shows the configuration of a position control system of the optical system driving device. In the present position control system, the X linear motor 20 and the Y linear motor 30 are respectively controlled by the position control devices 41 and 42 via the current amplifiers 43 and 44 based on the command values Xref and Yref of the X and Y axes, respectively. Drive. The displacement of the movable part is XY linear encoder 18
Is measured in a non-contact manner on the upper surface of the center table 15, and the measured X-axis direction displacement Xap and Y-axis direction displacement Yap are fed back to the position controllers 41 and 42 through the subtracters 45 and 46, respectively. Position control by so-called feedback control is performed.

Although the position control object of the present apparatus is originally the movement of the condenser lens 16 in the gas nozzle 17, the measurement by the XY linear encoder 18 is performed in the vicinity of the condenser lens 16. The measurement error (Abbe error) due to the pitching motion of the lens is designed to be low.

In this embodiment, the X linear motor 2 is used to ensure the following accuracy with respect to the trajectory command at the time of high speed / high acceleration / deceleration.
The 0 and Y linear motors 30 are arranged at the same height position as the center of gravity of the movable unit in FIG. 1 and the thrust generation direction (X-axis direction, Y-axis direction) of each motor is toward the center of gravity of the movable unit. are doing. As a result, the generation of the moment by the motor thrust is suppressed by the guide of the guide system, the pitching error is eliminated, and the trajectory accuracy during the acceleration / deceleration movement is secured.

In the present embodiment, X,
Although one set of linear motors is arranged on each axis of Y, if a higher acceleration is desired, as shown in FIG.
Two sets of linear motors 20-1, 20-2, 3 per axis
0-1 and 30-2 may be arranged. In this case, a pair of X linear motors 20-1 and 20-2 and a pair of Y linear motors 30-1 and 30-2 are arranged at target positions with the center table 15 therebetween.

In the above-described embodiment, the case where the present invention is applied to a laser processing apparatus has been described. However, the present invention is not limited to this.
It is also applicable to the -Y stage.

[0044]

Advantages of the Invention 1) It is possible to control the movement trajectory of the nozzle with high accuracy and high speed. Moreover, in the conventional machine, the orthogonality of the movement in the X-axis direction and the Y-axis direction depends on the assembly accuracy of the device. In the present invention, however, this error is small because it depends on the measurement accuracy of the XY linear encoder. it can.

2) In the conventional arrangement of the electromagnetic driving means, the thrust difference between the electromagnetic driving means generates an unnecessary moment in the guide system during the acceleration / deceleration movement. However, in the present invention, when the thrust of the linear motor is generated. This is a motor arrangement in which the motion error due to the moment is suppressed low.

3) By giving a command of an arbitrary shape to the linear motor, the linear motor can be moved to an arbitrary shape, and as a result, it becomes possible to process an arbitrary shape.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration of a main part when an optical system driving device according to the present invention is applied to a laser processing device.

FIG. 2 is a view of the apparatus of FIG. 1 as viewed from a line AA.

FIG. 3 is a diagram for explaining the X linear motor shown in FIG.

FIG. 4 is a top view for explaining a relationship between a coil and a permanent magnet in the X linear motor of FIG. 3;

FIG. 5 is a characteristic diagram showing a relationship between current and generated thrust of a linear motor used in the present invention.

FIG. 6 is a diagram showing a configuration of a position control system in the optical system driving device according to the present invention.

FIG. 7 is a diagram showing another example of a combination of linear motors used in the present invention.

FIG. 8 is a cross-sectional view showing a configuration of a main part for describing an example of a conventional optical system driving device.

FIG. 9 is a diagram for explaining a relationship between a condenser lens and a laser beam in FIG. 8;

FIG. 10 is a diagram showing a configuration of an electromagnetic driving means in FIG. 8;

FIG. 11 is a diagram for explaining a thrust generating action by an interaction between a permanent magnet and a coil in FIG. 10;

12 is a diagram for explaining a processing principle when the optical system driving device of FIG. 8 is applied.

FIG. 13 is a schematic diagram for explaining Abbe error in a conventional optical system driving device.

[Explanation of symbols]

 Reference Signs List 10 base plate 11 X-axis cross roller guide 12 Y-axis cross roller guide 13 machining head 14 intermediate stage 15 center table 16 condenser lens 17 gas nozzle 18 XY linear encoder 19 glass scale 20 X linear motor 21 X motor coil 22 yoke 23 permanent Magnet 24 Coil bobbin 30 Y linear motor 31 Y motor coil 100 Laser beam

Claims (4)

[Claims] 1. A table member on which an optical system is mounted and which is guided to move in a two-dimensional plane relative to a fixed base, and fixed to the fixed base so that magnetic pole faces face each other. The two-dimensional plane is fixed between the at least one pair of X-axis permanent magnets and the table member, and is located between the at least one pair of X-axis permanent magnets and interacts with a magnetic flux and current from the X-axis permanent magnet. X movable in the X-axis direction of
An X-axis drive system including a shaft coil; at least a pair of Y-axis permanent magnets fixed to the fixed base so that magnetic pole faces face each other; and the at least one pair of Y-axis fixed to the table member. Between the Y-axis permanent magnet and the magnetic flux from the Y-axis permanent magnet, and the Y-axis movable in the Y-axis direction in the two-dimensional plane by the interaction between the Y-axis permanent magnet and the current.
An optical system drive device comprising: a Y-axis drive system including a shaft coil. 2. The optical system driving device according to claim 1, wherein the X-axis driving system and the Y-axis driving system each have a substantially E-shaped yoke member fixed to the fixed base, and both outer sides thereof. Permanent magnets are fixed so that the same magnetic pole surfaces face each other inside the legs, and the center leg penetrates the coil, thereby constituting a voice coil type linear motor. Optical system drive. 3. The optical system driving device according to claim 2, wherein the extension length of the coil in the moving direction is longer than the extension length of the permanent magnet in the same direction as the moving direction by the stroke of the coil. An optical system driving device, comprising: 4. The optical system driving device according to claim 2, wherein the X-axis voice coil type linear motor and the Y-axis voice coil type linear motor each have a thrust acting on each coil applied to the table. An optical system driving device, which is arranged at a position facing a center of gravity of a movable portion including a member.