JPS63235090A - Laser beam machining apparatus - Google Patents

Abstract

PURPOSE:To improve the accuracy and to enable high speed machining by driving a reflecting mirror by a driving device translating through a translation- swing movement conversion mechanism and arranging an encorder in the driving device. CONSTITUTION:A step motor 15 is rotated at the prescribed rotating angle and this rotation is transferred to a ball screw 23 through a coupling 21, and a rod 25 is translated by the ball screw 23 at minute unit corresponding to the rotating angle of the motor. The translation of the rod 25 is converted to an angle variation of an arm 27 by a link mechanism composing of a ball pin 29 and a long groove 30 together with an axial point 31, while securing translation of the rod 25. This angle variation rotates the reflecting mirror 13, and spot of the laser beam 73 from a laser beam generator 11 can be scanned toward X-axis or Y-axis direction.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a laser processing device for processing ceramic wiring boards, etc., using a laser beam. The present invention relates to a laser processing apparatus that performs secondary processing without moving the workpiece by moving the workpiece to a desired position on a plane.

(Prior Art) Such laser processing devices can be roughly divided into two types. The first method is to fix the position of the laser spot and process the workpiece by moving the workpiece loaded on a moving stage such as an XY table according to the processing pattern with respect to the fixed spot position. On the other hand, the second method is a method in which the position of the workpiece is fixed and the laser spot is moved with respect to the fixed position of the workpiece using an optical path changing element such as a mirror. The first method is capable of machining a wide area of the workpiece, and the second method is capable of machining a small area of the workpiece, but compared to the first method, the moving mechanism part can be machined. Since it is not affected by the weight of the object, it has the advantage of being able to process at higher speeds and reducing the space of the entire device.

For this reason, the second method is generally adopted in laser processing apparatuses that process wiring on ceramic wiring boards and the like. This second method is called a beam scanner method, and there are two other methods: a galvano scanner and an XY scanner.

Of these, the principle of the galvanometer type scanner will be explained based on FIG.
and a reflecting mirror 4 connected thereto and rotating around a rotation axis perpendicular to the reflecting mirror 2, and a condenser that focuses the beam on a plane at a constant distance, which is formed by changing the angle of incidence with respect to the optical axis. It is composed of a lens, a so-called fθ lens 5.

That is, the reflection mirror 2 receives the laser beam output from the laser oscillator, the rotation angle of this is controlled by the galvanometer 1, the laser beam is scanned in the X direction, and the reflection mirror 4
to be transmitted.

The reflection mirror 4 is controlled to rotate in a direction perpendicular to the reflection mirror 2 by the galvanometer 3, and the laser beam is scanned in the Y direction and transmitted to the fθ lens 5.

The fθ lens 5 focuses the laser beam scanned in the X and Y directions by the reflecting mirror 1.2 onto the surface of the workpiece 6 to perform processing. This mechanism has small inertia of the moving parts and is suitable for high-speed machining.

(Problem to be solved by the invention) However, since the rotation angle of the galvanometer 1.3 during processing is small (3 to 4.5 degrees), it is difficult to install a position correction device such as an encoder to improve reproducibility. This method has the disadvantage that it is difficult and the desired positioning accuracy cannot be obtained.

SUMMARY OF THE INVENTION The present invention aims to eliminate the above-mentioned conventional drawbacks and provide a laser processing apparatus that can perform laser processing at high speed and with high precision.

(Means for solving the problem) A laser processing apparatus of the present invention includes a laser beam generator,
An optical path changing element for changing a beam path of a laser, a driving device for driving the element, an optical system for forming a laser beam spot, and a mounting table for placing a workpiece, and driven by the driving device. In a laser processing device that processes a workpiece by scanning a spot of a laser beam in a two-dimensional direction using an optical path changing element, the driving device is a translational movement mechanism that performs translational drive, and the driving device further includes a link mechanism. The driving device is coupled to an arm member fixed to the reflecting mirror via the drive device to convert the translational movement by the driving device into an angular displacement of the arm member to cause an angular displacement of the reflecting mirror, and the driving device further includes a positioning device. Therefore, the present invention is characterized by being provided with an encoder that detects the amount of movement and feeds it back.

(Function) According to the present invention, the drive device for driving the optical path changing element is a translational movement mechanism, and the translational movement of the translational movement mechanism is caused by the angular displacement of the arm member fixed to the reflecting mirror by the link mechanism.
Therefore, since the configuration is such that the angular displacement of the reflective mirror is converted to drive the reflective mirror, the translational movement can be increased compared to a small angular displacement of the reflective mirror.
Therefore, the position can also be finely adjusted. Furthermore, by disposing an encoder in the translational movement mechanism, errors in position control are compensated for, and the reproducibility of the laser beam spot is improved.

Furthermore, by appropriately changing the length of the arm member and the length from the reflecting mirror to the workpiece, the accuracy of the translation mechanism can be changed by the ratio of these, and by setting this ratio to an appropriate value. , machining accuracy can be increased.

(Example) Embodiments of the present invention will be described based on the drawings.

FIG. 1 shows an example of a laser processing apparatus according to the present invention.

In this figure, for clarity of explanation, we will explain the case where the laser beam is scanned in the -dimensional direction, that is, the spot of the laser beam 1 is scanned in the primary direction by driving the reflecting mirror in the X-axis or Y-axis direction. do. However, it is intended that spot scanning in two-dimensional directions can be easily understood from now on.

11 is a laser beam generator, 13 is a reflection mirror that reflects the laser beam, 15 is a step motor that drives the reflection mirror 13, and 17 is a workpiece scanned by the laser beam spot, such as a ceramic wiring board. are shown respectively.

A ball screw 23 is coupled to the shaft 19 of the step motor 15 via a coupling 21, and the ball screw 23 converts the rotational motion of the step motor 15 into translational motion.

A rod 25 is provided on the ball screw 23, and this rod 25 is connected to an arm 27 via a link mechanism. This link mechanism connects a ball pin 29 provided at the tip of a rod 25 to a long groove 30 provided at one end of an arm 27.
It is constructed by fitting the

In this link mechanism, the ball pin 29 slides within the long groove 30 in response to the translational movement of the rod 25, thereby ensuring the translational movement of the rod 25. The other end of the arm 27 is fixed to a reflecting mirror 13, and the reflecting mirror 13 is disposed such that its center is rotatable about an axis 31 perpendicular to the plane of the drawing. Therefore, when the ball pin 29 slides in the long groove 30 as the rod 25 translates, the arm 27 swings around the shaft 31. Therefore arm 2
A reflecting mirror 13 fixed to the other end of the mirror 7 swings about the shaft 31.

By the way, the step motor 15 is provided with a rotary encoder 33.
outputs a pulse proportional to the rotation angle of the input shaft, and by feeding this output back to the step motor 15, the rotation angle of the step motor 15 can be corrected by a known control circuit. This encoder 33 is essential for more accurate positioning.

The operation of the laser processing apparatus configured as described above will be explained below.

When the step motor 15 rotates to a predetermined rotation angle, this rotation is transmitted to the ball screw 23 via the coupling 21, and the ball screw 23 translates the rod 25 in minute units according to the rotation angle of the motor. move it. rod 2
5, the translational movement of the rod 25 is ensured by a link mechanism composed of a ball pin 29 and a long groove 30, and the arm 27 is caused to wrestle with the shaft 31 to cause an angular displacement of the arm 27. This angular displacement causes the reflection mirror 13 to By rotating, the spot of the laser beam 33 from the laser beam generator 11 can be scanned in the X-axis or Y-axis direction.

By the way, the step motor 15 is a rotary encoder 3.
3 has a semi-closed loop, and errors in the rotation angle of the motor are compensated for, but thermal expansion of the rod 25 and arm 27, errors in the ball screw, and errors in the link mechanism still remain. Distance to axis of movement. The accuracy can be changed by the ratio between the distance L2 and the distance L2 from the optical axis to the workpiece.

For example, when the step motor 15 and the ball screw 23 can translate with an accuracy of 1μ, Ll
: If L2・10:1, on the workpiece, 0, 1
It is possible to scan with an accuracy of μ.

An example of the laser processing apparatus of the present invention has been described above, and as a modification of this laser processing apparatus, a case will be described in which the driving device is a linear motor.

FIG. 2 shows a schematic diagram of a modified example. This modification differs from the device shown in FIG. 1 in that the linear motor 55 and its positioning devices, linear encoders 6163 and 65, are replaced by a step motor and a rotary encoder. Furthermore, the link mechanism has been changed from a ball pin and long groove to a linear ball bearing 67.

First, to briefly explain the structure of this modified example, a shaft 59 that extends from a linear motor 55 and moves in translation by the drive of the linear motor 55 has a slit plate 61 in which slits are formed at regular intervals in the middle part of the shaft 59. A light emitting diode (LED) 63 is disposed on one surface side of this slit plate 61, and a phototransistor (PT) or photodiode (PT) is disposed on the opposite surface side.
PD) 65 is disposed, and the light from the light emitting diode 63 that has passed through the thrift plate 61 is transferred to the phototransistor 65.
The amount of movement is counted and the signal is used for feedback control.

The end of the shaft 59 is rotatably attached to a linear ball bearing 67 that slides on an arm 69, and the arm 69 is fixed to a reflecting mirror 53.
is rotatable about a shaft 71. Therefore, by the same operation as in the first embodiment, the translational movement of the shaft 59 is controlled by the arm 6.
9 is converted into an oscillating motion of the reflecting mirror 53. Note that 51 is a laser beam generator, and 57 is a workpiece scanned by the spot of the laser beam.

Briefly explaining the operation of the modified example configured in this way, the shaft 59 is translated by a predetermined amount by the linear motor 55, and this translational movement is carried out by the linear ball bearing 67.
This is converted into a rotational movement of the arm 69 about the axis 71 of the reflecting mirror 53, resulting in a rotational movement of the reflecting mirror 53, and the beam from the laser beam generator 51 is reflected by this reflecting mirror 53, and the workpiece is 57 one-dimensional scans can be performed. This modification differs from the embodiment shown in FIG. 1 in that the rotational movement of the motor can be omitted by using a linear motor, which contributes to higher accuracy.

Further, the translational movement is performed by a photoelectric linear encoder 61,
The amount of movement is detected by 63 and 65 and fed back to the linear motor 55 to efficiently move the shaft 5.
Move 9. For example, if the linear motor 55 is controlled to accelerate or decelerate using a trapecloid curve, high-speed positioning without residual vibration or overshoot can be performed. Further, the change in accuracy is the same as the explanation regarding FIG. 1.

Above, an example has been described in which the laser processing device of the present invention scans the surface of a workpiece in one dimension. However, in order to scan the laser processing device in a two-dimensional direction, it is necessary to separate Two-dimensional scanning can be easily achieved by appropriately arranging these devices and rotating these reflecting mirrors in the X-axis direction and the Y-axis direction, respectively.

(Effects of the Invention) According to the laser processing device of the present invention, by driving the reflecting mirror through the translational-oscillation motion conversion mechanism and by mounting an encoder on the driving device, semi-closed Troop control improves accuracy and enables high-speed machining comparable to galvanometer methods.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a laser processing apparatus of the present invention, FIG. 2 is a schematic diagram showing a modification of the embodiment shown in FIG. 1, and FIG. 3 is an explanatory diagram showing the principle of a conventional galvano scanner. .

Claims (1)

[Claims] 1. A laser beam generator, an optical path changing element that changes the beam path of the laser, and a driving device that drives the element;
It is equipped with an optical system that forms a spot of a laser beam, and a mounting table on which a workpiece is placed, and the spot of the laser beam is divided into two by an optical path changing element driven by the drive device.
In a laser processing device that processes a workpiece by scanning in a dimensional direction, the drive device is a translational movement mechanism that performs translational drive, and the drive device is further coupled to an arm member fixed to a reflecting mirror via a link mechanism. and converts the translational movement by the drive device into an angular displacement of the arm member to cause an angular displacement of the reflecting mirror, and further, the drive device is provided with an encoder that detects and feeds back the amount of movement for positioning. A laser processing device characterized by the following.