WO2013011731A1 - Device for detecting amount of surface inclination, processing position control device, and laser processing apparatus - Google Patents

Abstract

A device for detecting an amount of surface inclination is provided with: a part to be detected (11Y) as a first electrode that carries out the same movement as a galvano mirror (3Y) disposed on a rotating axis for the galvano mirror (3Y), which makes laser light deviate to a processing position set in a processing area; a fixed electrode (14Y) as a second electrode fixed and disposed so as to be separated by a prescribed distance from the part to be detected (11Y); a voltage detection part that detects a voltage across the electrodes corresponding to the electrostatic capacity between the part to be detected (11Y) and the fixed electrode (14Y); and an detection part for the amount of surface inclination that detects the amount of inclination of the galvano mirror (3Y) based on the voltage across the electrodes. The part for detecting the amount of surface inclination calculates the distance between the electrodes, which is the distance between the part to be detected (11Y) and the fixed electrode (14Y) as the amount of inclination of the galvano mirror (3Y).

Description

Surface tilt amount detection device, processing position control device, and laser processing device

The present invention relates to a surface tilt detection device, a processing position control device, and a laser processing device that detect surface tilt of a galvano scanner.

A laser processing apparatus that performs laser processing on a workpiece controls a laser beam irradiation position (processing position) on the workpiece by a galvano scanner. When the galvano scanner repeatedly moves the machining position at the same pitch, the surface tilt resonance of the rotor and the mirror is induced depending on the movement cycle of the machining position movement. When resonance occurs, the processing position is displaced in the direction orthogonal to the moving direction of the processing position by the galvano scanner.

However, the surface tilt resonance phenomenon cannot be detected only by detecting the angular position of the galvano scanner using an encoder. In addition, there is a method of reducing the surface tilt resonance phenomenon by strictly adjusting the weight balance of the rotor. However, as the required positioning speed increases, the excitation force increases. It has become difficult to obtain positioning accuracy. As a method for detecting such surface-inclined resonance, there is a method for detecting surface-inclined resonance based on the beam position of laser light (see, for example, Patent Documents 1 and 2).

JP-A 63-285512 JP-A-61-128222

However, the former and latter conventional techniques have a problem that it is difficult to actually detect the surface tilt of the galvanometer mirror because the configuration of the apparatus for detecting the beam position of the laser light is complicated and expensive. .

The present invention has been made in view of the above, and an object thereof is to obtain a surface tilt amount detection device, a processing position control device, and a laser processing device that easily detect the surface tilt of a galvanometer mirror with a simple configuration. .

In order to solve the above-described problems and achieve the object, the present invention is arranged on a rotation axis of a galvano mirror that deflects laser light to a processing position set in a processing area and performs the same operation as the galvano mirror. According to the capacitance between the first electrode, the second electrode fixedly spaced from the first electrode by a predetermined distance, and the capacitance between the first electrode and the second electrode A voltage detector that detects an interelectrode voltage between the first electrode and the second electrode; a surface tilt amount detector that detects a surface tilt amount of the galvanometer mirror based on the interelectrode voltage; The surface tilt amount detection unit calculates an inter-electrode distance that is a distance between the first electrode and the second electrode as the surface tilt amount of the galvanometer mirror.

According to the present invention, based on the inter-electrode voltage corresponding to the capacitance between the first electrode and the second electrode, the surface tilt amount of the galvano mirror is calculated as the first electrode and the second electrode. Since the distance between the electrodes, which is the distance between the two, is calculated, it is possible to easily detect the surface tilt of the galvanometer mirror with a simple configuration.

FIG. 1 is a diagram illustrating a configuration of a laser processing apparatus according to an embodiment. FIG. 2 is a block diagram illustrating a configuration of the control device. FIG. 3 is a diagram showing the configuration of the galvanometer mirror. FIG. 4 is a diagram illustrating a configuration of the surface tilt amount detection unit. FIG. 5 is a diagram illustrating another configuration of the surface tilt amount detection unit. FIG. 6 is a diagram illustrating the configuration of the galvano scanner. FIG. 7 is a diagram for explaining the surface tilt resonance phenomenon. FIG. 8 is a diagram for explaining the deviation amount of the reflection angle. FIG. 9 is a diagram for explaining the relationship between the displacement amount of the inter-electrode distance and the tilt angle of the mirror surface. FIG. 10 is a diagram for explaining the relationship between the deviation amount of the reflection angle and the deviation amount of the laser light irradiation position. FIG. 11 is a diagram for explaining the relationship between the deflection angle of the galvanometer mirror and the deviation amount of the reflection angle. FIG. 12 is a diagram showing a laser beam irradiation position when there is no deviation in the reflection angle. FIG. 13 is a diagram showing a laser beam irradiation position when there is a deviation in the reflection angle. FIG. 14 is a diagram for explaining the amount of positional deviation in the X direction. FIG. 15 is a diagram for explaining positional deviation correction in the X direction. FIG. 16 is a diagram illustrating a connection configuration between the detected portion and the fixed electrode. FIG. 17 is a diagram illustrating a configuration example of a capacitance detection sensor. FIG. 18 is a diagram for explaining a method for calculating the distance between the detected portion and the fixed electrode. FIG. 19 is a diagram illustrating the relationship between the capacitance and the inter-electrode distance. FIG. 20 is a diagram showing the relationship between the interelectrode voltage and the interelectrode distance. FIG. 21 is a diagram illustrating a configuration of the surface tilt amount detection unit when the interelectrode distance is calculated using the interelectrode voltage. FIG. 22 is a diagram illustrating a configuration example of a current source circuit. FIG. 23 is a diagram illustrating another configuration example of the capacitance detection sensor. FIG. 24 is a diagram illustrating a circuit configuration example of a circuit that performs voltage detection according to the distance between the electrodes. FIG. 25 is a diagram for explaining a conversion method from the detection voltage to the inter-electrode distance. FIG. 26 is a diagram illustrating a hardware configuration of the control device. FIG. 27 is a diagram for explaining an example of processing for creating instruction information to be sent to the galvanometer mirror. FIG. 28 is a diagram for explaining the change period of the surface tilt amount. FIG. 29 is a diagram for explaining another example of processing for creating instruction information to be sent to the galvanometer mirror. FIG. 30 is a diagram illustrating another configuration example of the fixed electrode. FIG. 31A is a diagram illustrating a configuration example of shield wiring. FIG. 31-2 is an enlarged view of the fixed electrode.

Hereinafter, the surface tilt amount detection device, the processing position control device, and the laser processing device according to the embodiment of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram illustrating a configuration of a laser processing apparatus according to an embodiment. The laser processing apparatus 100 is an apparatus that forms a minute hole in the workpiece W by irradiation (cycle pulse mode) with laser light (pulse laser light) L1.

In this embodiment, an electrostatic capacitance type distance sensor is attached to each of the X-axis and Y-axis galvanometer mirrors, and the amount of displacement (deviation amount) of the mirror surface due to surface tilt resonance of the galvanometer mirror is detected. Then, the positional deviation of the laser beam irradiation position (processing position) with respect to the displacement of the galvano mirror is canceled by the galvano mirror on which the mirror surface of the galvano mirror is not displaced, thereby improving the positioning accuracy of the processing position.

A laser processing apparatus 100 performs laser processing of a laser oscillator 1 that oscillates a laser beam L0, an image transfer optical mechanism 2 that shapes the laser beam L0 and adjusts it to a desired beam shape and beam energy, and a workpiece (workpiece) W. A laser processing unit 4 and a control device 20 are provided. In this cycle pulse mode, a plurality of drilling positions set on the workpiece W are sequentially scanned, and a laser beam is irradiated to each hole in a plurality of cycles (a cycle in which laser light is irradiated one shot at a time). Is processed multiple times).

Laser oscillator 1 oscillates laser beam L0 and sends it to image transfer optical mechanism 2. The image transfer optical mechanism 2 includes a collimation lens 2C and a mask 2M. The collimation lens 2C collects the laser beam L0 from the laser oscillator 1 and adjusts (parallelizes) the optical axis, and the mask 2M shapes the beam shape of the laser beam L0.

The laser processing unit 4 includes galvanometer mirrors 3X and 3Y, galvanometer scanners 5X and 5Y, an fθ lens 6, an XY table 8, and a surface tilt amount detection unit 10A. The galvano scanners 5X and 5Y have a function (positioning function) for changing the trajectory of the laser light L0 to move the irradiation position on the workpiece W, and for scanning the laser light L0 in the XY direction. Then, the galvanometer mirrors 3X and 3Y are rotated to a predetermined angle. Accordingly, the galvano scanners 5X and 5Y cause the galvanometer mirrors 3X and 3Y to deflect the laser light L1 to the processing position set in the processing area.

The galvanometer mirrors 3X and 3Y reflect the laser beam (light beam) L0 emitted from the mask 2M of the image transfer optical mechanism 2 and deflect it at an arbitrary angle. The galvanometer mirror 3X deflects the laser beam L0 in the X direction, and the galvanometer mirror 3Y deflects the laser beam L0 in the Y direction. The fθ lens 6 deflects the laser beam L0 in a direction perpendicular to the surface of the workpiece W, and condenses (irradiates) the laser beam L0 on the processing position (surface) of the workpiece W.

The galvanometer mirrors 3X and 3Y are respectively provided with detected parts (detected parts 11X and 11Y to be described later) that are used for detection of surface tilt resonance (wobbling). The detected part 11X included in the galvano mirror 3X is used for detecting the surface tilt resonance of the galvano mirror 3X, and the detected part 11Y included in the galvano mirror 3Y is used for detecting the surface tilt resonance of the galvano mirror 3Y. In the present embodiment, fixed electrodes (fixed electrodes 14X and 14Y described later) are arranged in the vicinity of the detected portions 11X and 11Y in order to detect surface tilt resonance that occurs during laser processing.

It is connected to the detected part 11X and the fixed electrode 14X, and is connected to the detected part 11Y and the fixed electrode 14Y. The surface tilt amount detection unit 10 </ b> A detects the amount of mirror surface displacement (surface tilt amount) due to surface tilt resonance of the galvanometer mirrors 3 </ b> X and 3 </ b> Y, and sends the detection result to the control device 20.

The surface tilt amount detection unit 10A is configured to detect the detected unit 11X based on the capacitance between the detected unit 11X and the fixed electrode 14X that changes according to the distance between the detected unit 11X and the fixed electrode 14X. The distance to the fixed electrode 14X is detected. Similarly, the surface tilt amount detection unit 10A detects the detection target based on the capacitance between the detection unit 11Y and the fixed electrode 14Y that changes according to the distance between the detection unit 11Y and the fixed electrode 14Y. The distance between the part 11Y and the fixed electrode 14Y is detected. The distance between the detected part 11X and the fixed electrode 14X and the distance between the detected part 11Y and the fixed electrode 14Y vary according to the surface tilt amount of the galvanometer mirrors 3X and 3Y, respectively.

The control device 20 is based on the detection result (the distance between the detected part 11X and the fixed electrode 14X, the distance between the detected part 11Y and the fixed electrode 14Y) sent from the surface tilt amount detecting part 10A. The position of the galvanometer mirrors 3X and 3Y is corrected. The control device 20 is configured by a computer such as a personal computer, and controls the laser oscillator 1, the image transfer optical mechanism 2, and the laser processing unit 4 by NC (Numerical Control) control or the like.

The workpiece W is a printed circuit board or the like, and a plurality of drilling processes are performed. The XY table 8 is used to place a workpiece W, and freely moves in a two-dimensional X-axis / Y-axis plane by driving an X-axis motor and a Y-axis motor (not shown). The XY table 8 moves the processing area irradiated with the laser light L1 in the XY direction.

FIG. 2 is a block diagram showing the configuration of the control device. The control device 20 is connected to the surface tilt amount detection unit 10A, and the surface tilt amount detection unit 10A is connected to the detected portions 11X and 11Y and the fixed electrodes 14X and 14Y. The control device 20 is connected to the XY table 8, the laser oscillator 1, and the galvano scanners 5X and 5Y.

The control device 20 includes an input unit 21, a machining program storage unit 22, a correction amount calculation unit 23, an instruction creation unit 24, and an output unit 25. The input unit 21 receives the detection result (distance between electrodes corresponding to the surface tilt amount of the galvano mirrors 3X and 3Y) from the surface tilt amount detection unit 10A and sends it to the correction amount calculation unit 23.

The machining program storage unit 22 is a memory that stores a machining program used for laser machining of the workpiece W. In the machining program, a machining position (coordinates) on the workpiece W is set.

The correction amount calculation unit 23 calculates a correction amount of the laser beam irradiation position (hereinafter referred to as a processing position correction amount) based on the surface tilt amount of the galvanometer mirrors 3X and 3Y. In the control device 20, the relationship between the machining position correction amount and the surface tilt amount is stored in advance in the machining program storage unit 22, and the correction amount calculation unit 23 detects the relationship between the machining position correction amount and the surface tilt amount and the detection. A machining position correction amount is calculated based on the surface tilt amount. The correction amount calculation unit 23 sends the calculated machining position correction amount to the instruction creation unit 24.

The instruction creating unit 24 creates instruction information for the XY table 8 and the laser oscillator 1 based on the machining program in the machining program storage unit 22. In addition, the instruction creation unit 24 creates instruction information for the galvano scanners 5X and 5Y based on the machining program. In addition, the instruction creating unit 24 according to the present embodiment creates a corrected position command for correcting the position command to the galvano scanners 5X and 5Y using the machining position correction amount calculated by the correction amount calculating unit 23. The instruction creating unit 24 creates a correction position command so that the positional deviation of the laser beam irradiation position caused by the surface tilt resonance is canceled (so that the desired laser beam irradiation position is irradiated with the laser beam). The instruction creating unit 24 creates instruction information (position instruction) for the galvano scanners 5X and 5Y using the position instruction based on the machining program and the corrected position instruction.

The instruction creating unit 24 sends the created instruction information to the output unit 25. The output unit 25 sends instruction information to the galvano scanners 5X and 5Y to the galvano scanners 5X and 5Y, and sends instruction information to the XY table 8 and the laser oscillator 1 to the XY table 8 and the laser oscillator 1, respectively.

Here, the configuration of the galvanometer mirrors 3X and 3Y will be described. Since the galvano mirror 3X and the galvano mirror 3Y have the same configuration, the configuration of the galvano mirror 3Y will be described below. Since the galvano scanner 5X and the galvano scanner 5Y have the same configuration, the galvano scanner 5Y will be described when describing the galvano scanner.

FIG. 3 is a diagram showing the configuration of the galvanometer mirror. The detected part 11Y is arranged on the rotation axis of the galvanometer mirror 3Y (substantially on the same axis as the rotor 52) and performs the same operation as the galvanometer mirror 3Y. The detected portion 11Y and the galvanometer mirror 3Y rotate with the axial direction of the rotor 52 as the rotation axis when positioning the machining position in the Y direction (operation a), and in the case of surface tilt resonance, the galvanometer mirror 3Y Move in a direction substantially perpendicular to the mirror surface (operation b).

The galvano mirror 3Y has a substantially flat plate shape. For example, the detected portion 11Y is arranged at one end (front end) in the longitudinal direction of the main surface, and is configured by a rod-like member at the other end (rear end). The rotor 52 is joined.

The detected portion 11Y has, for example, a cylindrical shape, and is joined to the galvanometer mirror 3Y so that its column axis is in the same direction as the column axis of the rotor 52. The detected part 11Y is formed using a conductor.

The rotor 52 is configured to be able to rotate with its column axis as a rotation axis. When the rotor 52 rotates, the galvano mirror 3Y rotates, so that the detected part 11Y has a shaft similar to the galvano mirror 3Y. Rotate.

In the vicinity of the detected part 11Y, the fixed electrode 14Y is arranged at a position separated by a predetermined distance so as not to contact the detected part 11Y even when there is a surface-inclined resonance. When surface tilt resonance occurs, the mirror surface of the galvano mirror 3Y tilts. The fixed electrode 14Y is fixedly disposed at a position facing the detected portion 11Y so that the distance between the fixed electrode 14Y and the detected portion 11Y that changes according to the tilt amount of the mirror surface can be detected.

The fixed electrode 14Y has a parallel curved surface that is substantially parallel to a part of the side surface (curved surface) of the detected part 11Y, and the curved surface of the detected part 11Y and the curved surface of the fixed electrode 14Y face each other at substantially equal distances. Thus, the fixed electrode 14Y is arranged. For example, the fixed electrode 14Y has a shape in which a part (bottom surface) of a rectangular parallelepiped is cut off. The shape cut out from the rectangular parallelepiped is a columnar shape having a substantially meniscus upper surface and bottom surface, and the columnar curved surface forms a parallel curved surface surrounding a part of the curved surface of the detected portion 11Y.

In other words, the opposing surface that faces the fixed electrode 14Y in the detected portion 11Y has a part of a cylindrical side surface, and the opposing surface that faces the detected portion 11Y in the fixed electrode 14Y is a cylindrical inner wall surface. Have some. And the to-be-detected part 11Y and the fixed electrode 14Y are arrange | positioned so that a part of inner wall surface of a cylinder may surround a part of side surface of a cylinder.

Note that the detected portion 11Y and the fixed electrode 14Y may have a configuration in which the shape of the fixed electrode 14Y and the shape of the detected portion 11Y illustrated in FIG. 3 are interchanged. Moreover, although the case where the to-be-detected part 11Y was provided in the front-end | tip of the galvanometer mirror 3Y was demonstrated here, you may arrange | position the to-be-detected part 11Y in any position.

FIG. 4 is a diagram illustrating a configuration of the surface tilt amount detection unit. The surface tilt amount detection unit 10A includes a capacitance detection sensor 15 and a displacement amount calculation unit 16A. The electrostatic capacity detection sensor 15 is connected to the detected part 11Y and the fixed electrode 14Y, and detects the electrostatic capacity between the detected part 11Y and the fixed electrode 14Y. The capacitance detection sensor 15 sends the detected capacitance to the displacement amount calculation unit 16A.

The displacement amount calculation unit 16A converts the capacitance into a distance between the detected unit 11Y and the fixed electrode 14Y, and sends the conversion result (distance information) to the control device 20. The distance information is a distance (distance between the electrodes) between the detected portion 11Y and the fixed electrode 14Y according to the surface tilt amount (tilt amount) of the galvanometer mirror 3Y, and according to the angle deviation amount of the galvanometer mirror 3Y. Change. Note that the displacement amount calculation unit 16A may convert the distance information into a surface tilt amount and use the surface tilt amount as the distance information. The surface tilt amount is a displacement amount of the distance between the electrodes, and corresponds to an angle deviation amount from the reference position of the mirror surface.

The control device 20 creates instruction information (galvano command) to the galvano scanner 5X using the distance information from the displacement amount calculation unit 16A, and sends it to the galvano scanner 5X. As described above, when the surface tilt resonance occurs, a correction value is included in the axis (galvano mirror 3X) orthogonal to the axis (galvano mirror 3Y) where the surface tilt resonance occurs in order to cancel the surface tilt amount. Send a galvo command.

In addition, even if the distance between the detected part 11Y and the fixed electrode 14Y is the same, the capacitance between the detected part 11Y and the fixed electrode 14Y depends on the rotation angle (galvano angle position) of the galvano mirror 3Y. The capacitance may change. For this reason, the displacement amount calculation unit 16A may convert the capacitance into a capacitance according to the distance between the detected portion 11Y and the fixed electrode 14Y using the galvano angle position. This makes it possible to calculate an accurate capacitance.

FIG. 5 is a diagram showing another configuration of the surface tilt amount detection unit. Note that description of components having the same configuration as the surface tilt amount detection unit 10A of FIG. 4 is omitted. The surface tilt amount detection unit 10B here includes a displacement amount calculation unit 16B instead of the displacement amount calculation unit 16A. The displacement amount calculation unit 16 </ b> B includes a correction unit 17.

In order to reflect surface tilt resonance phenomenon in positioning servo control in real time, the detected surface tilt amount is added to (or subtracted from) the detected angle of the orthogonal axis to correct the misalignment due to surface tilt. Can do. As a result, it is possible to cancel the surface tilt resonance after starting to move to the target position in real time. Depending on the setting and arrangement of the positive and negative directions of the rotation axis, the setting of the X-axis direction, and the setting of the Y-axis direction, canceling the amount of surface tilt may result in addition or subtraction of a correction amount for the command position or detection position There is a case. For this reason, the sign for the correction calculation is set so that the cancel mechanism works appropriately.

The galvano angle position detected by an angle detector (encoder) 58 described later is input to the displacement amount calculation unit 16B. The correction unit 17 converts the electrostatic capacitance into a distance between the detected unit 11Y and the fixed electrode 14Y using the galvano angle position. In other words, the correction unit 17 corrects the distance between the detected portion 11Y corresponding to the capacitance and the fixed electrode 14Y to a distance according to the galvano angle position. In the following description, a case where the surface tilt amount detection unit 10B includes the displacement amount calculation unit 16B will be described.

FIG. 6 is a diagram showing the configuration of the galvano scanner. The galvano scanner 5Y includes a part of the rotor 52 extending from the galvano mirror 3Y side. In the galvano scanner 5Y, bearings 55, 57, a mirror driving unit 56, and an angle detector 58 are arranged on the rotor 52. The rotor 52 is rotatably supported by bearings 55 and 57.

The bearing 55 is disposed between the mirror driving unit 56 and the galvano mirror 3Y, and the bearing 57 is disposed between the mirror driving unit 56 and the angle detector 58. The rotor 52 expands and contracts in the axial direction due to the temperature change. For this reason, the bearing 55 is not completely fixed in the axial direction with respect to the rotor 52, and the rotor 52 is configured to pass through the bearing 55 when the rotor 52 expands and contracts. On the other hand, the bearing 57 fixes the rotor 52 in the axial direction.

The mirror driving unit 56 rotates the galvanometer mirror 3Y about the column axis of the rotor 52 as a rotation axis. The mirror drive unit 56 is configured using, for example, a magnet and a coil, and generates a torque with the magnet by flowing a current through the coil. As a result, the rotor 52 and thus the galvanometer mirror 3Y work so as to rotate.

The angle detector 58 is an encoder, for example, and detects the rotation angle (galvano angle position) of the galvanometer mirror 3Y. The angle detector 58 sends the detected galvano rotation angle to the displacement amount calculation unit 16B and the control device 20.

Here, the surface tilt resonance phenomenon will be described. FIG. 7 is a diagram for explaining the surface tilt resonance phenomenon. In FIG. 7, illustration of the mirror driving unit 56 and the angle detector 58 is omitted. The surface tilt resonance phenomenon is a phenomenon in which the galvanometer mirror 3Y swings in a direction substantially perpendicular to the mirror surface. For example, in the case of the galvanometer mirror 3Y, since the bearing 57 fixes the rotor 52 in the axial direction, a surface tilt resonance phenomenon occurs on the end side (galvanometer mirror 3Y side) of the bearing 57. The surface tilt resonance phenomenon is a phenomenon in which the angle of the mirror surface of the galvano mirror 3Y is changed by the deflection of the rotor 52 and the galvano mirror 3Y with the bearing 57 as a fixed part, and the traveling direction of the deflected laser light L0 is deviated. .

When the galvano scanner 5Y repeats the movement of the machining position at the same pitch in the same direction, the surface tilt resonance of the rotor 52 and the galvano mirror 3Y occurs at a certain movement cycle. In other words, the surface tilt resonance occurs when the moving period is close to the reciprocal of the surface tilt resonance frequency of the rotor 52 including the galvano mirror 3Y when the machining position is moved in the same direction at an equal pitch.

Surface tilt resonance is a natural vibration of mechanical bending of the rotor 52 including the galvanometer mirror 3Y. When the galvano movement is performed at an equal pitch, the acceleration / deceleration of the rotation of the galvano mirror 3Y occurs periodically. If the galvanometer mirror 3Y and the rotor 52 are unbalanced in weight from the center of this rotational motion, a shaft swing phenomenon occurs, and the rotational acceleration is converted into a shaft bending force. When this bending force becomes an excitation force, and the period is close to the period of the face-to-face resonance frequency, the face-to-face vibration gradually increases and a large position shift (position shift of the laser beam irradiation position) occurs at the machining point. Will occur. The position shift due to the surface tilt resonance appears, for example, in a direction perpendicular to the traveling direction of the machining position.

Therefore, if a surface tilt resonance occurs in the galvanometer mirror 3X that performs positioning in the X direction, the machining position is shifted in the Y direction. Similarly, when surface tilt resonance occurs in the galvanometer mirror 3Y that performs positioning in the Y direction, the processing position is shifted in the X direction.

During surface tilt resonance, the rotor 52 and the galvanometer mirror 3Y swing in a direction substantially perpendicular to the mirror surface of the galvanometer mirror 3Y with the bearing 55 and the bearing 57 as fixed positions. As a result, the reflection angle of the laser beam L0 at the galvano mirror 3Y is deviated by a predetermined amount from the desired reflection angle.

For example, in a state where the rotor 52 and the galvano mirror 3Y are bent to the maximum on the back side of the galvano mirror 3Y, the laser beam L0 is reflected by the reflection angle (+ θ1) in the X direction and reflected as the laser beam L2. On the other hand, in a state where the rotor 52 and the galvano mirror 3Y are bent to the maximum on the front side of the galvano mirror 3Y, the laser beam L0 is reflected by the reflection angle (−θ1) in the X direction and reflected as the laser beam L3.

In other words, when the rotor 52 and the galvano mirror 3Y are bent due to surface tilt resonance, the reflection angle of the laser beam L0 with respect to the X direction causes a shift amount corresponding to the bending amount. When the rotor 52 and the galvano mirror 3Y are bent to the maximum, the deviation amount of the reflection angle in the X direction of the laser light L0 is also maximized.

When the reflection angle of the laser beam L0 is shifted in the X direction, the position of the detected part 11X is shifted. For this reason, the distance between the detected part 11X and the fixed electrode 14X changes, and the electrostatic capacitance between the detected part 11X and the fixed electrode 14X changes. Similarly, when the reflection angle of the laser beam L0 is shifted in the Y direction, the position of the detected portion 11Y is shifted. For this reason, the distance between the detected part 11Y and the fixed electrode 14Y changes, and the electrostatic capacitance between the detected part 11Y and the fixed electrode 14Y changes. In the present embodiment, the positional deviation (processing) of the laser light irradiation position is based on the capacitance between the detected portion 11X and the fixed electrode 14X and the capacitance between the detected portion 11Y and the fixed electrode 14Y. (Positional deviation) is corrected.

FIG. 8 is a diagram for explaining the deviation amount of the reflection angle. When the face-down resonance does not occur in the rotor 52 and the galvanometer mirror 3Y, the rotor 52 and the galvanometer mirror 3Y do not bend toward the front surface side or the back surface side of the galvanometer mirror 3Y. In this case, there is no deviation in the reflection angle of the laser light L0 with respect to the X direction. Therefore, the laser beam L0 is reflected as the laser beam L1 at a desired reflection angle by the galvanometer mirror 3Y.

On the other hand, in the state where the rotor 52 and the galvano mirror 3Y are bent toward the front side or the back side of the galvano mirror 3Y, the reflection angle in the X direction is shifted and reflected as the laser light L2 or the laser light L3.

FIG. 9 is a diagram for explaining the relationship between the displacement amount of the inter-electrode distance and the tilt angle of the mirror surface. The displacement amount Dx of the inter-electrode distance is a deviation amount from the initial value of the inter-electrode distance, and changes according to the deflection amount of the rotor 52 and the galvano mirror 3Y due to surface tilt resonance. The surface tilt amount is detected by detecting a displacement amount Dx of the detected portion 11Y (mirror tip) in the surface tilt direction. Surface tilt occurs when the rotor 52 and the galvanometer mirror 3Y are bent with the bearing 55 and the bearing 57 as fulcrums. Therefore, if the distance from the bearing 55 that fixes the rotor 52 in the axial direction to the detected portion 11Y is L (mm), the displacement amount Dx (μm) of the inter-electrode distance, the rotor 52 and the galvanometer mirror 3Y The relationship with the deflection angle Φ (rad), which is the tilt angle, is Φ = Dx / (L × 1000).

FIG. 10 is a diagram for explaining the relationship between the deviation amount of the reflection angle and the deviation amount of the laser light irradiation position. In Figure 10, the galvanometer mirror 3Y, deviated laser beam L0 only the reflection angle theta ₂ in the X-direction shows a laser beam irradiation position P1 when it is reflected as the laser beam L4.

When the laser beam L0 is reflected by the galvanometer mirror 3Y without shifting the reflection angle in the X direction, the laser beam irradiation position on the workpiece W is shifted to the desired laser beam irradiation position P0 in the X direction. Laser light L0 is irradiated. Therefore, when the laser beam L0 is reflected by the reflection angle θ _{2 in the} X direction and reflected as the laser beam L4, the distance between the laser beam irradiation position P0 and the laser beam irradiation position P1 is the irradiation position deviation amount (laser beam). Irradiation position deviation amount) Δx. In this case, if the focal length of the fθ lens 6 is f, Δx = fθ ₂ .

Thus, the inclination of the galvanometer mirror 3Y in the surface tilt direction appears as an angle shift of the reflection angle of the laser light L0. Then, from the characteristics of the fθ lens 6, the angle deviation amount (change amount) θ _{2 of} the laser light L 4 is converted into a position displacement (irradiation position deviation amount) that satisfies Δx = fθ ₂ as a processing position.

FIG. 11 is a diagram for explaining how much the position to be processed is shifted when the galvanometer mirror is generally changed in angle Φ. When the galvanometer mirror 3Y bends at the deflection angle Φ, the laser light L0 is reflected by the reflection angle (2Φ) in the X direction and reflected as the laser light L4.

The laser beam irradiation position when the deflection angle of the galvano mirror 3Y is 0 is defined as the laser beam irradiation position P2, and the laser beam irradiation position when the galvano mirror 3Y is bent at the deflection angle Φ is defined as the laser beam irradiation position P3. When the galvano mirror 3Y bends at the bending angle Φ, the distance between the laser beam irradiation position P2 and the laser beam irradiation position P3 becomes the irradiation position deviation amount Δx. In this case, when the focal length of the fθ lens 6 is f, Δx = 2fΦ.

Thus, the deflection angle (tilt) Φ of the galvanometer mirror 3Y changes the emission angle of the laser light L4 by 2 × Φ. Therefore, Δx = 2f × Dx / (L × 1000). The actual surface tilt includes not only the linear deflection from the bearing 57 but also the curvature of the shaft (rotor 52) and the galvanometer mirror 3Y. For this reason, not only the irradiation position deviation amount Δx and the inter-electrode distance displacement amount Dx are treated as a linearly proportional relationship, but a higher-order equation that matches the actual phenomenon may be used.

The laser processing apparatus 100 may correct the position command to the galvano scanners 5X and 5Y based on the relationship between the deflection angle Φ of the galvano mirror 3Y and the irradiation position deviation amount Δx. In this case, the relationship between the deflection angle Φ of the galvano mirror 3Y and the irradiation position deviation amount Δx is stored in advance in the surface tilt amount detection unit 10B. Then, the surface tilt amount detection unit 10B calculates the deflection angle Φ based on the displacement amount Dx of the interelectrode distance. Further, based on the stored relationship and the deflection angle Φ of the galvano mirror 3Y, the surface tilt amount detection unit 10B calculates the irradiation position deviation amount Δx.

Note that the control device 20 may calculate the irradiation position deviation amount Δx. In this case, the relationship between the deflection angle Φ of the galvano mirror 3Y and the irradiation position deviation amount Δx is stored in advance in a memory such as the machining program storage unit 22. Then, based on the stored relationship and the deflection angle Φ of the galvano mirror 3Y, the control device 20 calculates a machining position correction amount corresponding to the irradiation position deviation amount Δx.

FIG. 12 is a diagram showing a laser beam irradiation position when there is no deviation in the reflection angle, and FIG. 13 is a diagram showing a laser beam irradiation position when there is a deviation in the reflection angle. 12 and 13 show the laser beam irradiation position when the laser beam L1 is irradiated at an interval d (pitch d) in the Y direction on the workpiece W from the negative to the positive direction. Specifically, the laser beam L1 is irradiated in the order of the first laser beam irradiation position H1, the second laser beam irradiation position H2, and the nth laser beam irradiation position Hn (n is a natural number of 3 or more). Is done.

As shown in FIG. 12, when there is no deviation in the reflection angle in the X direction, no deviation occurs in the laser beam irradiation position in the X direction. Then, the laser beam L1 is irradiated at an interval d in the Y direction on the workpiece W.

On the other hand, as shown in FIG. 13, when there is a deviation in the reflection angle in the X direction, a deviation occurs in the laser light irradiation position in the X direction. For this reason, the laser beam L5 is irradiated with a gap d in the Y direction on the workpiece W and with a positional shift amount corresponding to the shift amount of the reflection angle in the X direction. In the laser processing apparatus 100, the workpiece W may be irradiated with the laser beam L5 at a predetermined cycle (frequency), and the galvano mirror 3Y may be surface-reared and resonated at a predetermined cycle. In this case, in each laser beam irradiation position, a positional deviation amount in the X direction according to the emission frequency of the laser beam L5 and the surface tilt resonance frequency of the galvanometer mirror 3Y is generated.

In this case, in the example shown in FIG. 13, since there is no movement command in the X direction, it is desirable that the processing should proceed straight in the + Y direction. However, in actuality, displacement vibration of about ± 10 μm may occur at the processing point due to induction of surface tilt resonance. For example, when the laser processing apparatus 100 is a printed circuit board drilling laser processing apparatus, surface tilt resonance with a period of about 1 ms often occurs.

FIG. 14 is a diagram for explaining the amount of positional deviation in the X direction. Instruction information (Y mirror position command) for moving the laser light irradiation position by a predetermined distance d (here 2 mm) in the Y direction is sent to the galvanometer mirror 3Y.

Also, the laser oscillator 1 is sent with instruction information for emitting a pulse of the laser beam L0 at each laser beam irradiation position. When the laser beam L0 is emitted in pulses, the laser oscillator 1 is controlled so that the laser output P has a predetermined peak value. Here, a case is shown in which instruction information is sent to the galvanometer mirror 3Y and the laser oscillator 1 so that the laser beam L0 is irradiated to eight laser beam irradiation positions.

The surface tilt resonance of the galvanometer mirror 3Y is a surface tilt resonance in which the laser beam irradiation position is shifted in the X direction. When the galvanometer mirror 3Y resonates and resonates at a predetermined cycle, the surface tilt amount of the galvanometer mirror 3Y also changes at a predetermined cycle. When the galvano mirror 3Y resonates with a predetermined period, the laser beam L5 is irradiated to a position on the workpiece W according to the resonance position of the mirror surface of the galvano mirror 3Y at the timing when the laser beam L0 is emitted. . Thereby, for example, the amount of positional deviation in the X direction of the laser light irradiation position changes at a predetermined cycle.

FIG. 15 is a diagram for explaining positional deviation correction in the X direction. Here, the positional deviation correction with respect to the positional deviation amount in the X direction described with reference to FIG. 14 will be described. When the galvanometer mirror 3Y resonates due to surface tilt, the laser light irradiation position is displaced by a distance (X direction) corresponding to the surface tilt amount. Therefore, in the present embodiment, the correction amount calculation unit 23 of the control device 20 calculates a processing position correction amount for correcting the irradiation position deviation amount Δx corresponding to the surface tilt amount of the galvanometer mirror 3Y. The laser beam irradiation position is shifted in the X direction by the surface tilt resonance generated in the galvanometer mirror 3Y. Therefore, the correction amount calculation unit 23 calculates the processing position correction amount for the galvano mirror 3X. The processing position correction amount for the galvanometer mirror 3X is a correction amount for the position command to the galvanometer mirror 3X.

When the position command to the galvanometer mirror 3X is 0, the surface tilt amount of the galvanometer mirror 3X is also zero. In this case, the galvanometer mirror 3X is controlled based on the machining position correction amount calculated by the correction amount calculation unit 23. Therefore, instruction information (X mirror position command) for moving the laser light irradiation position by the position correction amount corresponding to the machining position correction amount with respect to the X direction is sent to the galvanometer mirror 3X.

Next, a method for measuring the irradiation position deviation will be described. FIG. 16 is a diagram illustrating a connection configuration between the detected portion and the fixed electrode. As shown in the figure, the detected part 11Y and the fixed electrode 14Y are arranged apart from each other by a predetermined distance. And the to-be-detected part 11Y and the fixed electrode 14Y are each connected to the current source 61 which is an alternating current source. The current source 61 is disposed, for example, in the aforementioned capacitance detection sensor 15.

FIG. 17 is a diagram illustrating a configuration example of a capacitance detection sensor. Here, the capacitance of the capacitor 62 formed by the detected portion 11Y and the fixed electrode 14Y is indicated by a capacitance Cx. Of the wiring between the detected portion 11Y and the current source 61 and the wiring between the fixed electrode 14Y and the current source 61, the wiring connected to the OP amplifier 64 (for example, the fixed electrode 14Y and the current source 61). Is shielded by a shield wire 60 or the like.

As an angular frequency of the current to which ω is applied, when a current I ₀ sinωt is supplied from the current source 61 at a voltage of Vs, a current of i is supplied to the capacitor 62 at a voltage of Vx (interelectrode voltage). The non-inverting input side of the OP amplifier 64 is connected to the wiring between the detected portion 11Y and the current source 61 or the wiring between the fixed electrode 14Y and the current source 61. A shield line 60 is connected to the inverting input side and the output side of the OP amplifier 64.

In this case, i = Vs × jωCx holds. Therefore, Vs = i / jωCx. When the shield of the wiring by the shield line 60 is good, Vs and the interelectrode voltage Vx are substantially equal. Therefore, the value of the interelectrode voltage Vx can be obtained by measuring Vs. As described above, since the shield wire 60 is arranged in the capacitance detection sensor 15, the interelectrode voltage Vx can be measured without being affected by the stray capacitance of the metal (wiring) around the capacitor 62. Is possible. Of the wires connecting the capacitor 62 and the current source 61, the wire on the side where the OP amplifier 64 is not connected may be connected to the ground.

The calculation unit 63 of the capacitance detection sensor 15 detects the interelectrode voltage Vx that changes according to the capacitance Cx, calculates the capacitance Cx using the value of the interelectrode voltage Vx, and calculates the displacement amount calculation unit. 16B calculates the inter-electrode distance D between the detected portion 11Y and the fixed electrode 14Y using the capacitance Cx. FIG. 18 is a diagram for explaining a method for calculating the distance between the detected portion and the fixed electrode.

In FIG. 18, for convenience of explanation, the detected portion 11Y is indicated by a disk-like electrode 63A, and the fixed electrode 14Y is indicated by a disk-like electrode 63B. Electrode distance D between the electrode 63A and the electrode 63B is D, if the electrode 63A, the area of 63B which is S, respectively, if established relationship S»D ² is (S is compared to the square of D And much larger), Cx = ε × S / D. Therefore, the displacement amount calculation unit 16B calculates the inter-electrode distance D using the relationship of Cx = ε × S / D and the value of the capacitance Cx. Here, ε is the dielectric constant between the electrodes. Therefore, since the capacitance Cx is inversely proportional to the interelectrode distance D, the change in the interelectrode distance D can be measured by determining the change in the capacitance Cx.

The displacement amount calculation unit 16B stores the relationship between the interelectrode distance D and the capacitance Cx in advance, and calculates the interelectrode distance D based on the relationship between the interelectrode distance D and the capacitance Cx. Also good. FIG. 19 is a diagram illustrating the relationship between the capacitance and the inter-electrode distance. For example, the displacement amount calculation unit 16B calculates the inter-electrode distance D using the relationship between the capacitance Cx and the inter-electrode distance D illustrated in FIG.

Further, the displacement amount calculation unit 16B stores in advance the relationship between the displacement amount Dx of the inter-electrode distance and the capacitance Cx, and based on the relationship between the displacement amount Dx of the inter-electrode distance and the capacitance Cx, A distance displacement amount Dx may be calculated.

Further, the displacement amount calculation unit 16B stores in advance the relationship between the interelectrode voltage Vx and the interelectrode distance D applied between the electrodes, and based on the relationship between the interelectrode voltage Vx and the interelectrode distance D, the interelectrode distance D is stored. May be calculated. FIG. 20 is a diagram showing the relationship between the interelectrode voltage and the interelectrode distance. The displacement amount calculation unit 16B calculates the interelectrode distance D using, for example, the relationship between the interelectrode voltage Vx and the interelectrode distance D shown in FIG. The relationship between the interelectrode distance D and the capacitance Cx shown in FIG. 19 and the relationship between the interelectrode voltage Vx and the interelectrode distance D shown in FIG. 20 are stored in the displacement amount calculation unit 16B, for example.

Further, the displacement amount calculation unit 16B stores in advance the relationship between the interelectrode voltage Vx applied between the electrodes and the displacement amount Dx of the interelectrode distance, and is based on the relationship between the interelectrode voltage Vx and the displacement amount Dx of the interelectrode distance. Thus, the displacement amount Dx of the interelectrode distance may be calculated.

The configuration of the surface tilt amount detection unit when the surface tilt amount detection unit calculates the inter-electrode distance D using the relationship between the interelectrode voltage Vx and the inter-electrode distance D will be described. FIG. 21 is a diagram illustrating a configuration of the surface tilt amount detection unit when the interelectrode distance is calculated using the interelectrode voltage. Here, the case where one electrode of the capacitor 62 is connected to the current source 61 and the other electrode is connected to the ground is shown. The surface tilt amount detection unit 10 </ b> C includes a high impedance voltage detection unit 68, a rectifier circuit 69, an A / D conversion unit 70, an interelectrode distance calculation unit 71, and a correction unit 17.

The high impedance voltage detector 68 detects the voltage between the electrodes of the capacitor 62 (interelectrode voltage), and the detected interelectrode voltage is converted into a direct current by the rectifier circuit 69. The direct current voltage converted into direct current by the rectifier circuit 69 is subjected to A / D conversion (conversion from an analog signal to a digital signal) by the A / D conversion unit 70. Then, the interelectrode distance calculation unit 71 calculates the interelectrode distance D using the A / D converted signal. At this time, the interelectrode distance calculation unit 71 calculates the interelectrode distance D using, for example, the relationship between the interelectrode voltage Vx and the interelectrode distance D shown in FIG. Then, the correction unit 17 corrects the interelectrode distance D to the interelectrode distance D corresponding to the galvano angle position. The correction unit 17 sends the corrected inter-electrode distance D to the control device 10.

The correction amount calculation unit 23 of the control device 20 calculates the machining position correction amount for correcting the position command to the galvano scanners 5X and 5Y using the inter-electrode distance D calculated by the displacement amount calculation unit 16B. In the control device 20, the relationship between the inter-electrode distance D and the machining position correction amount is stored in advance in the machining program storage unit 22 or the like. The correction amount calculation unit 23 calculates the machining position correction amount using the relationship between the interelectrode distance D and the machining position correction amount.

Note that the relationship between the interelectrode voltage Vx and the machining position correction amount may be stored in advance, and the machining position correction amount may be calculated based on the relationship between the interelectrode voltage Vx and the machining position correction amount. In this case, the displacement amount calculation unit 16B may calculate the machining position correction amount, or the correction amount calculation unit 23 may calculate the machining position correction amount. When the displacement amount calculation unit 16B calculates the machining position correction amount, the relationship between the interelectrode voltage and the machining position correction amount is stored in, for example, the displacement amount calculation unit 16B. When the correction amount calculation unit 23 calculates the machining position correction amount, the relationship between the interelectrode voltage and the machining position correction amount is stored in the machining program storage unit 22, for example.

FIG. 22 is a diagram illustrating a configuration example of a current source circuit. Here, the case where the current source circuit of the current source 61 is connected to the ground is shown. The current source circuit of the current source 61 includes an AC voltage source 65 that generates a voltage of E ₀ sinωt, an OP amplifier 72, and a resistor 73 having a resistance value R. As a result, a current of i = E ₀ / Rsinωt is generated from the current source 61. For example, good characteristics can be obtained when an AC frequency of about 250 kHz to 1 MHz and a resistor of about R = 100 kΩ to 1 MΩ are used.

FIG. 23 is a diagram showing another configuration example of the capacitance detection sensor. The description of the same components as those of the capacitance detection sensor shown in FIG. 17 is omitted. One electrode of the capacitor 62 is connected to the ground, and the other electrode is connected to the non-inverting input side of the OP amplifier 64 and the current source 61. The shield line 60 is connected to the inverting input side and the output side of the OP amplifier 64. With this configuration, the calculation unit 63 detects the interelectrode voltage Vx and calculates the capacitance Cx using the value of the interelectrode voltage Vx, and the displacement amount calculation unit 16B detects the detected value using the capacitance Cx. An interelectrode distance D between the portion 11Y and the fixed electrode 14Y is calculated.

Since a high-impedance detection circuit is required so that current from the applied current source i does not flow into the voltage detection circuit side, a voltage follower configuration is used. Moreover, the electric wire connected to the electrode (the fixed electrode 14Y or the detected part 11Y) actually has a stray capacitance, and an excess current flows, resulting in a detection error. For this reason, the same voltage as the detection voltage is applied to the shield line 60 through buffer amplification with a low output impedance so that the influence of stray capacitance does not appear.

Here, another example of the voltage detection method according to the interelectrode distance D will be described. FIG. 24 is a diagram illustrating a circuit configuration example of a circuit that performs voltage detection according to the distance between the electrodes. The voltage detection circuit shown in FIG. 24 includes an AC voltage source 77, a constant current amplifier circuit 79, a phase shift circuit 83, a voltage detection circuit 80, a synchronous rectification circuit 81, and a low-pass filter 82.

One electrode of the capacitor 62, the constant current amplification circuit 79, and the voltage detection circuit 80 are connected. Here, the case where the fixed electrode 14Y, which is one electrode of the capacitor 62, is connected to the constant current amplifier circuit 79 and the voltage detection circuit 80, and the detected part 11Y, which is the other electrode, is connected to the ground will be described. To do.

The AC voltage source 77 is used as a reference waveform generation source, and the constant current amplifier circuit 79 outputs an AC current proportional to the input voltage. The voltage detection circuit 80 detects a voltage (voltage drop) generated in the fixed electrode 14Y. The phase shift circuit 83 shifts the phase of the input AC voltage source 77 to advance the phase to a predetermined phase or process the phase to be output.

The AC voltage source 77 and the constant current amplifier circuit 79 generate an input signal, and the phase shift circuit 83 and the synchronous rectifier circuit 81 have an AC signal detected by the voltage detection circuit 80 and an AC signal generated by the AC voltage source 77. And the frequency and phase of these are matched.

In the voltage detection circuit 80 shown in FIG. 24, the AC constant voltage sin2πft generated by the AC voltage source 77 is input to the constant current amplifier circuit 79. The constant current amplifier circuit 79 outputs an AC current proportional to the input voltage and is fixed. Supply to the electrode 14Y. At this time, the voltage Vc of the fixed electrode 14Y is applied to the voltage detection circuit 80 as Vc = i / 2πfC, but the input impedance of the voltage detection circuit 80 is very large, and the value of the current flowing into the voltage detection circuit 80 is Can be ignored. The voltage detected by the voltage detection circuit 80 is input to the synchronous rectification circuit 81.

The synchronous rectifier circuit 81 synchronously rectifies the detection signal of the voltage detection circuit 80 based on the phase information of the signal of the phase shift circuit 83, rectifies a signal of only a specific frequency that has passed through the phase shift circuit 83, Remove frequency components. The output of the synchronous rectifier circuit 81 is input to the low pass filter 82. The low-pass filter 82 removes unnecessary high frequency components and obtains an accurate detection output (interelectrode voltage Vx) as a distance information output. The voltage generated at both ends of the capacitance Cx is delayed by 90 ° with respect to the applied current i, but the phase is matched by the phase shift circuit 83 so that a synchronous detection output is obtained. Yes. Therefore, the synchronous rectification circuit 81 can extract the detection signal of the voltage detection circuit 80 by synchronous rectification based on the phase information of the signal of the phase shift circuit 83. As a result, the low-pass filter 82 can remove unnecessary high-frequency components from the signal input as the output of the synchronous rectification circuit 81 and output an accurate detection output as distance information.

Thus, in the voltage detection circuit, even if noise components mixed in the signal are superimposed, the noise components can be removed because the frequencies do not match. As a result, it is possible to detect a voltage that ignores the influence of noise components.

Next, a conversion method from the detection voltage (interelectrode voltage Vx) to the interelectrode distance D will be described. When the area of the electrode is ideally infinite, there is an inversely proportional relationship between the capacitance Cx and the inter-electrode distance D. However, since the area is actually finite, it is out of the inversely proportional relationship. As shown in FIG. 19, there is a relationship that the capacitance Cx decreases as the interelectrode distance D increases. When the capacitance Cx decreases, the interelectrode voltage Vx increases. Therefore, as the interelectrode distance D increases, the interelectrode voltage Vx increases. However, since it has a finite electrode area, it deviates from the ideal inverse proportion, and actually there is a monotone curve relationship between the interelectrode distance D and the interelectrode voltage Vx as shown in FIG.

The conversion from the interelectrode voltage Vx to the interelectrode distance D is performed by the interelectrode distance calculation unit 71 of the displacement amount calculation unit 16B shown in FIG. FIG. 25 is a diagram for explaining a conversion method from the detection voltage to the inter-electrode distance. Since the relationship between the displacement of the interelectrode distance D and the interelectrode voltage Vx is not linear as shown in FIG. 20, an interelectrode distance calculation unit 71 is provided so that it is convenient for subsequent processing. The signal is converted so that the displacement of the distance D is proportional to the output signal.

The interelectrode distance calculation unit 71 receives an A / D converted signal (A / D conversion value X of the interelectrode voltage). The interelectrode distance calculation unit 71 converts the A / D conversion value X of the interelectrode voltage into the interelectrode distance D using a correction formula such as AX ⁴ + BX ³ + CX ² + DX + E. As described above, the interelectrode distance calculation unit 71 converts the interelectrode voltage Vx into the interelectrode distance D by using a fourth-order polynomial approximation formula or the like. The correction formula used when the A / D conversion value X of the interelectrode voltage is converted into the inter-electrode distance D is not limited to the quartic formula, and may be a correction formula of the third order or lower, or the fifth order or higher. It may be a correction formula.

FIG. 26 is a diagram illustrating a hardware configuration of the control device. In FIG. 26, the whole structure of the control system of the laser processing apparatus 100 is shown. The control device 20 includes a processing machine control unit 88, galvano control units 90X and 90Y, and a table drive control unit 92. The processing machine control unit 88 is based on the surface tilt amount of the galvano scanners 5X and 5Y sent from the processing program and the surface tilt amount detection unit 10B, and the galvano control units 90X and 90Y, the table drive control unit 92, and the laser oscillator 1 Send instruction information to.

The processing machine control unit 88 sends a position command in the X direction to the galvano control unit 90X, and sends a position command in the Y direction to the galvano control unit 90Y. Specifically, the processing machine control unit 88 sends commands for positioning target coordinates to the galvano scanners 5X and 5Y to the galvano control units 90X and 90Y.

In the present embodiment, when the galvano mirror 3X is tilted and resonates, the irradiation position of the laser beam L5 is shifted in the Y direction, so that a position command including a machining position correction amount is sent to the galvano controller 90Y. In addition, when the galvano mirror 3Y resonates and resonates, the irradiation position of the laser beam L5 shifts in the X direction, and therefore a position command including the machining position correction amount is sent to the galvano control unit 90X.

The galvano control unit 90X controls the galvano scanner 5X in accordance with the instruction information from the processing machine control unit 88. Further, the galvano control unit 90Y controls the galvano scanner 5Y according to the instruction information from the processing machine control unit 88. Specifically, the galvano controllers 90X and 90Y perform positioning servo operations on the galvano scanners 5X and 5Y, respectively. Then, the galvano scanners 5X and 5Y rotate the galvanometer mirrors 3X and 3Y, respectively, by a predetermined angle with the rotor 52 as the rotation axis.

The galvano mirrors 3X and 3Y are made of, for example, lightweight and highly rigid beryllium, and the galvano scanners 5X and 5Y are designed to have high rigidity. Therefore, the positioning operation can be completed at a much higher speed than when the machining position is controlled only by driving the XY table 8. The laser processing apparatus 100 performs positioning about 3000 times per second, for example.

Further, the processing machine control unit 88 instructs the laser oscillator 1 on conditions and timing for irradiating a laser pulse having a desired laser output and pulse width. Thereby, the laser oscillator 1 can emit a laser pulse at a timing required for processing.

As shown in FIG. 1, the laser processing apparatus 100 includes an XY table 8 on which the workpiece W is placed, and the control apparatus 20 controls a table drive control unit that controls the positioning of the XY table 8. 92. The table drive control unit 92 controls the drive of the servo amplifiers 93X and 93Y in order to control the positioning of the XY table 8 in the XY direction. As a result, the motors M94 and M94 operate to move the XY table 8 in the XY direction. Further, the table drive control unit 92 performs positioning drive control on the vertical height direction (Z direction) of the fθ lens 6 and the vertical height direction of the Z-axis head portion on which the galvano scanners 5X and 5Y are mounted. Specifically, the table drive control unit 92 drives and controls the servo amplifier 93Z. As a result, the motor M96 operates to move the fθ lens 6 and the Z-axis head portion in the Z direction.

FIG. 27 is a diagram for explaining an example of processing for creating instruction information to be sent to the galvano mirror. Since the galvano scanners 5X and 5Y have the same configuration, the configuration of the galvano scanner 5X will be described here.

The instruction creating unit 24 of the control device 20 uses a position command (position command in the X direction) based on the machining program and a corrected position command corresponding to the machining position correction amount to a position command ( Instruction information) is created. The instruction information sent from the control device 20 to the galvano scanner 5X is not limited to the position command but may be an angle command. Here, a case where the instruction information sent from the control device 20 to the galvano scanner 5X is an angle command will be described.

The instruction creating unit 24 converts the created position command into an angle command to the galvano mirror 3X, and the output unit 25 sends the converted angle command to the galvano scanner 5X. The galvano scanner 5X sends an angle command to the feed forward gain (Kff) 101. Further, the feedback gain (K) 102 is inputted by subtracting the angle command sent to the galvanometer mirror 3X from the angle command sent from the control device 20.

The acceleration (current signal) of the angle command output from the feedforward gain 101 is added to the angle command (current signal) output from the feedback gain 102 and input to the notch filter 103.

In the notch filter 103, the torsional resonance frequency component of the rotor 52 and the galvanometer mirror 3X is removed. The angle command from which the torsional resonance frequency is removed is sent to the torque conversion circuit 105 via the current amplifier gain (Ki) 104. The torque conversion circuit 105 multiplies the current by a torque constant K _T to convert it into torque, and further divides by the inertia J _S to output acceleration. The inertia here is the sum of the inertia of the rotor 52 and the inertia of the galvano mirror 3X.

Acceleration output from the torque conversion circuit 105 is sent to the integration circuits 106A and 106B and integrated by the integration circuits 106A and 106B. As a result, an angle command is output from the integrating circuit 106B to the galvanometer mirror 3X. This angle command is used for feedback control. Specifically, the angle command sent to the galvanometer mirror 3X is subtracted from the angle command sent from the control device 20 and sent to the feedback gain 102.

Note that since a predetermined time is required to detect the capacitance Cx between the electrodes, the correction position command may be created based on the change period of the surface tilt amount of the galvano mirror 3Y. In this case, the change cycle of the surface tilt amount of the galvanometer mirror 3Y is detected in advance, and the change cycle is set in the machining program storage unit 22 in the control device 20 or the like. Then, the correction amount calculation unit 23 issues a correction position command based on the change period of the surface tilt amount of the galvanometer mirror 3Y and the surface tilt amount of the galvanometer mirror 3Y detected by the surface tilt capacitance detection sensor 15. create. Specifically, the correction amount calculation unit 23 creates a correction position command for correcting, for example, the surface tilt amount detected in the previous cycle.

By the way, if the conventional galvano control system is a galvano scanner in the X-axis direction, in addition to a control system that feeds back a signal from a sensor (such as a rotary encoder) that detects the rotation angle of the axis, in order to perform positioning at high speed Assuming a model to be controlled in advance, positioning operation was performed using feedforward control.

However, information from other than the sensor that detects rotation is not used, and the configuration is not configured to suppress the surface collapse phenomenon that the shaft generates. In the present embodiment, in order to correct the surface tilt, the displacement amount of the machining position is obtained from the detected surface tilt amount. Then, the correction is performed by adding the displacement amount of the processing position to the position command to the galvano scanner 5X having the orthogonal axis. For this reason, it is configured to correct each other's position command so that mutual tilting of the surfaces in the X direction and the Y direction are similarly canceled. Thereby, the surface tilt amount Δy generated in the galvano mirror 3Y that controls the position in the X-axis direction is canceled by the galvanometer mirror 3Y in the Y-axis direction, and corresponds to the surface tilt amount generated in the galvano mirror 3Y in the Y-axis direction. The irradiation position deviation amount Δx can be canceled by the galvanometer mirror 3X in the X-axis direction. Therefore, even if the surface tilt phenomenon occurs, the laser beam L0 can be deflected to a desired target position, and laser processing with high accuracy can be performed.

FIG. 28 is a diagram for explaining a change cycle of the amount of surface collapse. In FIG. 28, the horizontal axis represents time (t), and the vertical axis represents the surface tilt amount (dy) of the galvanometer mirror 3Y. As shown in the figure, the surface tilt amount of the galvanometer mirror 3Y changes at a predetermined cycle.

FIG. 29 is a diagram for explaining another example of processing for creating instruction information to be sent to the galvanometer mirror. Here, a case where instruction information (angle command) to be sent to the galvanometer mirror 3X is created using the change period of the surface tilt amount will be described.

In the detection of the capacitance Cx, there is an arithmetic processing for obtaining the amplitude of the AC signal and converting the voltage into a distance as described above, and therefore there is a tendency to be slightly delayed from the actual phenomenon. When there is this delay, the correction accuracy may be improved by performing time difference compensation that performs delay processing for correcting the delay time. Since the surface tilt frequency is determined by the mechanical configuration and is substantially constant, if the distance detection delay time is corrected so as to have a specific time difference, the canceling effect works well. Therefore, the time difference compensation unit 107 is provided in the correction amount calculation unit 23. Then, the time difference compensation unit 107 adjusts the time difference of the correction processing in consideration of the delay with respect to the laser processing apparatus 100.

The time difference compensation unit 107 has a function of creating a correction position command for compensating for a delay time due to capacitance detection. The time difference compensation unit 107 creates a correction position command for correcting the amount of surface tilt detected in a cycle before a predetermined cycle (for example, one cycle). The time difference compensation unit 107 may create a correction position command based on the interelectrode voltage Vx before a predetermined period, the capacitance Cx before the predetermined period, and the distortion angle Φ before the predetermined period. Thus, the correction accuracy of the amount of surface tilt can be increased by performing the cancel operation in the state of surface tilt one cycle before.

The instruction creating unit 24 uses the position command (position command in the X direction) based on the machining program and the corrected position command for correcting the surface tilt amount detected in the previous cycle to the galvano scanner 5X. Position command is created. Thereafter, in the galvano scanner 5X, an angle command to be sent to the galvanometer mirror 3X is created by a process similar to the process described in FIG.

In the present embodiment, the case where the fixed electrode 14Y has a parallel curved surface substantially parallel to a part of the side surface (curved surface) of the detected portion 11Y has been described. However, the detected portion 11Y of the fixed electrode 14Y. The facing surface that faces is not limited to a curved surface. For example, the opposed surface of the fixed electrode 14Y that faces the detected portion 11Y may be a flat surface.

FIG. 30 is a diagram illustrating another configuration example of the fixed electrode. As shown in the figure, the fixed electrode 108 has a flat surface facing the detected portion 11Y. Here, the case where the fixed electrode 108 is disc-shaped and the disc-shaped bottom surface is a facing surface facing the detected portion 11Y is shown.

Next, the configuration of the shield wire 60 that shields the wiring between the fixed electrode 14Y and the current source 61 will be described. FIG. 31A is a diagram illustrating a configuration example of the shield wiring, and FIG. 31-2 is an enlarged view of the fixed electrode. The shield wire 60 is an outer conductor of a coaxial cable, for example. The center of the coaxial cable is a central conductor (wiring between the fixed electrode 108 and the current source 61), and the periphery of the central conductor is covered with insulating endothelium (not shown). Furthermore, the periphery of the insulating inner skin is covered with an outer conductor (shield wire 60), and the outer conductor is covered with an insulating outer skin (not shown).

Furthermore, the periphery of the fixed electrode 108 is covered with an insulator, and the periphery of the insulator is covered with a conductor 110. The fixed electrode 14Y may be covered with an insulator and the insulator may be covered with the conductor 110.

In this embodiment, the processing position correction amount is calculated based on the interelectrode voltage Vx, and the correction position command is generated from the processing position correction amount. However, the correction position command is generated from the interelectrode voltage Vx. May be. Further, a corrected position command may be created from any one of the capacitance Cx, the interelectrode distance D, the interelectrode distance displacement amount Dx, and the deflection angle Φ.

¡As the operating speed of galvano scanners and galvano mirrors increases, the angular acceleration increases, and the excitation force in the direction of surface tilt tends to increase. Furthermore, even with the same mechanical configuration, the amount of surface tilt is large, and it is difficult to achieve both the processing speed desired by the user and the processing accuracy. In the present embodiment, even when surface tilt resonance occurs by increasing the processing speed, the position command to the galvanometer mirrors 3X and 3Y is corrected based on the surface tilt amount. It is possible to achieve both accuracy.

Thus, according to the embodiment, based on the interelectrode voltage (potential difference) between the detected portion 11Y and the fixed electrode 14Y and the interelectrode voltage (potential difference) between the detected portion 11X and the fixed electrode 14X. Since the amount of surface tilt is detected, the amount of surface tilt can be easily detected with a simple configuration. Moreover, since the amount of surface tilt is detected based on the interelectrode voltage Vx corresponding to the capacitance Cx, the amount of surface tilt can be accurately detected. Therefore, even when surface tilt resonance occurs, the position command to the galvanometer mirrors 3X and 3Y can be accurately corrected based on the surface tilt amount, and the laser beam L1 is irradiated to a desired position. It becomes possible.

Further, since the opposing surfaces of the fixed electrode 14Y and the detected portion 11Y are parallel curved surfaces, it is possible to detect an accurate surface tilt amount regardless of the rotation angle of the galvanometer mirror 3Y. In addition, the opposing surface that faces the fixed electrode 14Y in the detected portion 11Y has a part of a cylindrical side surface, and the opposing surface that faces the detected portion 11Y in the fixed electrode 14Y is one of the inner wall surfaces of the cylinder. Since it has a portion, it is possible to detect an accurate amount of surface tilt.

Further, since the interelectrode distance (surface fall amount) is detected using the relationship between the interelectrode distance and the capacitance shown in FIG. 19, it is possible to easily detect the surface fall amount. Further, since the inter-electrode distance (surface fall amount) is detected using the relationship between the inter-electrode voltage and the inter-electrode distance shown in FIG. 20, it is possible to easily detect the surface fall amount.

In addition, since the correction position command is created based on the change period of the surface tilt amount of the galvano mirror 3Y, even if it takes time to detect the capacitance Cx, the position correction amount for the surface tilt is accurately performed. It becomes possible.

As described above, the surface tilt amount detection device, the processing position control device, and the laser processing device according to the present invention are suitable for laser processing while positioning to the processing position.

DESCRIPTION OF SYMBOLS 1 Laser oscillator 3X, 3Y Galvano mirror 4 Laser processing part 5X, 5Y Galvano scanner 10 Control apparatus 10A-10C Surface fall amount detection part 11X, 11Y Detected part 14X, 14Y, 108 Fixed electrode 15 Capacitance detection sensor 16A, 16B Displacement amount calculation unit 17 Correction unit 20 Control device 22 Machining program storage unit 23 Correction amount calculation unit 24 Instruction creation unit 52 Rotor 58 Angle detector 60 Shield wire 62 Capacitor 63 Calculation unit 63A, 63B Electrode 68 High impedance voltage detection unit 71 Electrode Distance calculation unit 90X, 90Y Galvano control unit 100 Laser processing device 107 Time difference compensation unit D Distance between electrodes Dx Displacement of distance between electrodes L0 to L5 Laser beam W Workpiece

Claims (14)

1. A first electrode disposed on a rotation axis of a galvano mirror for deflecting laser light to a processing position set in a processing area and performing the same operation as the galvano mirror;
   A second electrode fixedly disposed at a predetermined distance from the first electrode;
   A voltage detection unit that detects an interelectrode voltage between the first electrode and the second electrode according to a capacitance between the first electrode and the second electrode;
   A surface tilt amount detection unit for detecting the surface tilt amount of the galvanometer mirror based on the voltage between the electrodes;
   With
   The surface tilt amount detection unit calculates an inter-electrode distance that is a distance between the first electrode and the second electrode as the surface tilt amount of the galvanometer mirror. apparatus.
2. 2. The surface tilt amount detection device according to claim 1, wherein the surface tilt amount detection unit includes a correction unit that corrects the inter-electrode distance to an inter-electrode distance corresponding to a rotation angle of the galvanometer mirror.
3. The first opposing surface in which the first electrode opposes the second electrode and the second opposing surface in which the second electrode opposes the first electrode are parallel curved surfaces that are parallel to each other. The surface tilt amount detection device according to claim 1, wherein
4. A first storage unit that stores a first correspondence relationship that is a correspondence relationship between the inter-electrode voltage and the inter-electrode distance;
   4. The surface tilt amount detection apparatus according to claim 1, wherein the surface tilt amount detection unit calculates the inter-electrode distance using the first correspondence relationship.
5. A capacitance calculating unit that calculates the capacitance based on the voltage between the electrodes;
   The surface tilt amount according to any one of claims 1 to 3, wherein the surface tilt amount detection unit calculates the inter-electrode distance using the capacitance calculated by the capacitance calculation unit. Detection device.
6. A second storage unit that stores a second correspondence relationship that is a correspondence relationship between the capacitance and the inter-electrode distance;
   The surface tilt amount detection device according to claim 5, wherein the surface tilt amount detection unit calculates the inter-electrode distance using the second correspondence relationship.
7. The first opposing surface and the second opposing surface have one opposing surface having a part of a cylindrical side surface and the other opposing surface having a part of an inner wall surface of a cylinder, The surface tilt amount detection device according to claim 3, wherein the first electrode and the second electrode are arranged so that a part of the cylinder surrounds a part of a side surface of the cylinder.
8. A first electrode disposed on a rotation axis of a galvano mirror for deflecting laser light to a processing position set in a processing area and performing the same operation as the galvano mirror;
   A second electrode fixedly disposed at a predetermined distance from the first electrode;
   A voltage detection unit that detects an interelectrode voltage between the first electrode and the second electrode according to a capacitance between the first electrode and the second electrode;
   A control device that corrects a positional deviation of a processing position due to the surface tilt with respect to the galvanometer mirror that deflects the laser light in a deflection direction perpendicular to the deflection direction controlled by the galvanometer mirror in which the surface tilt occurs.
   With
   The said control apparatus produces | generates the correction command which correct | amends the said position shift based on the said electrode voltage, and outputs the produced | generated correction amount to the said galvanometer mirror, The machining position control apparatus characterized by the above-mentioned.
9. 9. The machining position control device according to claim 8, wherein the control device outputs the correction amount to a galvanometer mirror in which a positioning direction of the machining position is orthogonal to the galvanometer mirror in which the surface tilt is detected. .
10. The control device generates instruction information to the galvano mirror using the correction instruction and a position instruction to the galvano mirror according to a machining program, and outputs the generated instruction information to the galvano mirror. The processing position control apparatus according to claim 9.
11. Further comprising a surface tilt amount detection unit for detecting the surface tilt amount of the galvanometer mirror based on the voltage between the electrodes,
    The surface tilt amount detection unit calculates an inter-electrode distance, which is a distance between the first electrode and the second electrode, as the surface tilt amount of the galvanometer mirror.
    The machining position control device according to any one of claims 8 to 10, wherein the control device generates the correction command based on the surface tilt amount.
12. The control device extracts an inter-electrode voltage before a predetermined period from a change period of the inter-electrode voltage acquired in advance, and generates the correction command based on the extracted inter-electrode voltage. Item 9. The machining position control device according to Item 8.
13. A galvanometer mirror that deflects the laser beam to the machining position set in the machining area;
    A first electrode disposed on a rotation axis of the galvanometer mirror and performing the same operation as the galvanometer mirror;
    A second electrode fixedly disposed at a predetermined distance from the first electrode;
    A voltage detection unit that detects an interelectrode voltage between the first electrode and the second electrode according to a capacitance between the first electrode and the second electrode;
    A control device that corrects a positional deviation of a processing position due to the surface tilt with respect to the galvanometer mirror that deflects the laser light in a deflection direction perpendicular to the deflection direction controlled by the galvanometer mirror in which the surface tilt occurs.
    With
    The control device generates a correction command for correcting the positional deviation based on the inter-electrode voltage and outputs the generated correction amount to the galvanometer mirror.
    The galvanometer mirror deflects the laser beam to a machining position set in a machining area using the correction command.
14. The galvanometer mirror includes a first galvanometer mirror that positions a machining position in a first direction, and a second galvanometer mirror that positions a machining position in a second direction orthogonal to the first direction. Have
    The control device outputs the correction amount to the second galvanometer mirror when detecting a surface tilt from the first galvanometer mirror, and detects the surface tilt from the second galvanometer mirror, The laser processing apparatus according to claim 13, wherein the correction amount is output to a first galvanometer mirror.

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