Laser processing device

Abstract

To provide a laser processing device configured to suppress voltage drop influenced by a cable inductance component between an amplifier and a galvano-scanner.SOLUTION: A laser processing device is equipped with: galvano-scanners (6 and 7) provided with galvano-mirrors (61 and 71) and galvano actuators (62 and 72) that rotationally drive the galvano-mirrors (61 and 71); driving parts (16 and 17) that output driving voltages for driving the galvano-actuators (62 and 72); and cables (36a, 36b, 37a and 37b) through which the driving parts (16 and 17) are connected to the galvano-actuators (62 and 72). The cables (36a, 36b, 37a and 37b) are low inductance cables.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a laser processing apparatus.

Background Art

[0002] Conventionally, a laser processing apparatus that deflects a laser oscillated from a laser oscillator by a galvanometer scanner to position an irradiation position is known (see Patent Document 1). The galvanometer scanner is driven by a command signal from a galvanometer scanner control device being converted into an analog signal (a current command signal for the galvanometer scanner), and this current command signal being amplified by an amplifier and applied as a drive current to an actuator of the galvanometer scanner.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a laser processing apparatus as described in Patent Document 1 above, its processing speed has been steadily increasing, and accordingly, the demand for speeding up the galvanometer scanner has also been increasing. Here, to speed up the galvanometer scanner, it is necessary to shorten its control cycle (increase the drive frequency). However, when the current fluctuates at high speed, there is a problem that the voltage drop due to the inductance component of the cable connecting the above-mentioned amplifier and the actuator of the galvanometer scanner becomes large.

[0005] Therefore, an object of the present invention is to provide a laser processing apparatus in which the influence of voltage drop due to the inductance component of the cable between the amplifier and the galvanometer scanner is reduced.

Means for Solving the Problems

[0006] One aspect of the present invention is a laser processing apparatus characterized by comprising: a laser pulse generating unit; a galvanometer scanner equipped with a galvanometer mirror that reflects laser pulses emitted from the laser pulse generating unit; a galvanometer actuator that rotates the galvanometer mirror; a drive unit that outputs a drive voltage to drive the galvanometer actuator; and a cable connecting the drive unit and the galvanometer actuator, wherein the cable is a low-inductance cable. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a laser processing apparatus that reduces the effect of voltage drop due to the inductance component of the cable between the amplifier and the galvanometer scanner. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram of a laser processing apparatus according to an embodiment of the present invention. [Figure 2] (a) A diagram illustrating the drive frequency of the galvanometer scanner, (b) A schematic diagram showing the motor cable, and (c) A diagram showing the equivalent circuit of the motor cable. [Modes for carrying out the invention]

[0009] The laser processing apparatus according to an embodiment of the present invention will be described below with reference to the drawings. In the following description, the X-axis direction and the Y-axis direction refer to the state of the workpiece as viewed from a plan view.

[0010] As shown in Figure 1, the laser processing apparatus 1 according to this embodiment is a laser processing apparatus that performs hole drilling on a printed circuit board W, which is placed on a processing table 2 that is movable in the XY axis direction. In addition to the processing table 2 described above, it is equipped with a laser pulse generation unit 3, a scanning unit 4, a focusing (Fθ) lens 8, a control unit 10, and the like.

[0011] The laser pulse generation unit 3 is equipped with a laser oscillator, such as a carbon dioxide (CO2) laser oscillator, and is configured to emit laser pulses (pulsed lasers).

[0012] Furthermore, the scanning unit 4 is positioned downstream of the laser pulse generation unit 3 on the optical path of the laser beam and includes a first galvanoscanner 61 that scans the processing laser pulse in the X-axis direction and a second galvanoscanner 7 that scans in the Y-axis direction. These first and second galvanoscanners 6 and 7 are each equipped with galvanoscanner mirrors 61 and 71 that reflect the incident laser pulse and galvanoscanner motors 62 and 72 that adjust the rotation angle of the galvanoscanner mirrors 61 and 71.

[0013] The laser pulses for processing are positioned on the printed circuit board W in the XY axis direction by a pair of galvanometer scanners 6 and 7 of the scanning unit 4. The laser pulses positioned by these galvanometer scanners 6 and 7 are then incident on the fθ lens 8, focused onto the printed circuit board W, and laser processing such as drilling is performed.

[0014] The control unit 10 includes an overall control unit 11 that controls the entire laser processing apparatus 1, and a galvanometer control unit 12 that inputs position commands from the overall control unit 11, which are digital signals, as analog current commands to the motor drive circuits 16 and 17. The motor drive circuits 16 and 17, which act as galvanometers (hereinafter also called galvanometers), output a voltage based on the current commands. The current commands amplified by the motor drive circuits 16 and 17 become the drive current for the galvanometer motors 62 and 72, and the rotation angle of the galvanometer mirrors 61 and 71 is controlled by the driving of the galvanometer motors 62 and 72.

[0015] Furthermore, current detectors 26 and 27 are connected to motor cables 36 and 37 that connect the motor drive circuits 16 and 17 to the galvanometer motors 62 and 72. The galvanometer control unit 12 detects the drive current of the galvanometer scanners 6 and 7 using the current detectors 26 and 27, and performs feedback control on the command value (current command) based on the detected drive current.

[0016] In recent years, with the increasing speed of laser processing equipment, the period of the current command has become shorter, and as shown in Figure 2(a), the driving frequencies of the galvanometer scanners 6 and 7 have also increased. When the current fluctuates rapidly, the voltage drop due to the inductance component of the cable between the galvanometer amplifier and the galvanometer scanner can no longer be ignored.

[0017] Therefore, in this embodiment, the motor cables 36a, 36b, 37a, and 37b between the galvanometer amplifiers 16 and 17 and the galvanometer scanners 6 and 7 are made of low-inductance cables, as shown in Figure 2(b). Specifically, in this embodiment, the motor cables 36a, 36b, 37a, and 37b are made of a single coaxial cable or a cable in which multiple coaxial cables are connected in parallel.

[0018] This allows for lower inductance in motor cables 36a, 36b, 37a, and 37b, thereby reducing voltage drop across them. Furthermore, reducing voltage drop across motor cables 36a, 36b, 37a, and 37b suppresses the increase in drive voltage of galvanometers 62 and 72 in the feedback control of galvanometer amplifiers 16 and 17 described above. This allows for securing the output voltage necessary for increasing the speed of galvanometer scanners 6 and 7 while keeping the upper limit of the output voltage of the galvanometer amplifier low. As a result, the speed of galvanometer scanners 6 and 7 can be increased without increasing heat generation, increasing the size of the housing, or increasing costs.

[0019] For example, a motor cable or the like can be considered as an equivalent circuit as shown in Fig. 2(c). Therefore, the voltage drop ΔV of the cable is ΔV = R * A R = 2π * f * L f = 1 / T2 where in the above formula, A is the drive current, T2 is the period of the current command, and L is the cable inductance.

[0020] As an example, when the current command during the drive of the galvanoscanners 6 and 7 is 30A_10kHz, if a cable with a cable inductance of 5 μH that is not a coaxial cable is used, the voltage drop of the cable is 9.42V. On the other hand, when using a coaxial cable as in this embodiment and reducing the cable inductance to 0.5 μH, which is 1 / 10 times the original, it is possible to suppress the voltage drop of the cable to 0.942V, which is 1 / 10 times the original.

[0021] <Summary> The laser processing apparatus (1) according to this embodiment includes a laser pulse generation unit (3), a galvanomirror (61, 71) that reflects the laser pulse emitted from the laser pulse generation unit (3), and a galvanoscope (6, 7) including a galvanic actuator (62, 72) that rotationally drives the galvanomirror (61, 71), a drive unit (16, 17) that outputs a drive voltage for driving the galvanic actuator (62, 72), and a cable (36a, 36b, 37a, 37b) that connects the drive unit (16, 17) and the galvanic actuator (62, 72), where the cable (36a, 36b, 37a, 37b) is a low-inductance cable, which is a feature of this invention.

[0022] By using low-inductance cables 36a, 36b, 37a, and 37b to supply drive current to the galvanometer actuators 62 and 72, the voltage drop across cables 36a, 36b, 37a, and 37b can be kept low even when the drive frequency of the galvanometer scanners 6 and 7 is increased. As a result, the upper limit of the output voltage of the drive units 16 and 17 can be kept low, enabling faster response times for the galvanometer scanners 6 and 7 and increasing the processing speed, while allowing the drive units 16 and 17 to be configured with low loss, compactness, and low cost.

[0023] In the above-described embodiment, the galvanometer mirrors 61 and 71 were rotationally driven by galvanometer motors 62 and 72. However, for example, a piezo actuator may be used as the galvanometer actuator that rotationally drives the galvanometer mirrors 61 and 71. Also, galvanometer amplifiers 16 and 17 were used as the drive unit that outputs the drive voltage for the galvanometer actuator, but an inverter may be used instead. Furthermore, in the above-described embodiment, coaxial cables were used as the cables 36a, 36b, 37a, and 37b through which the drive current for the galvanometer scanners 6 and 7 flows. However, twisted pair wires or parallel plate structured power supply lines may be used instead. [Explanation of symbols]

[0024] 1: Laser processing equipment 3: Laser pulse generation unit 6,7: Galvanometer Scanner 16,17: Drive unit (galvanometer amplifier) 61,71: Galvano Mirror 62,72: Galvanometer actuator (galvanometer motor) 36a, 36b, 37a, 37b: Cable (motor cable)

Claims

1. a laser pulse generating unit; a galvanometer scanner including a galvanometer mirror that reflects the laser pulse emitted from the laser pulse generating unit and a galvanometer actuator that rotationally drives the galvanometer mirror; a driving unit that outputs a driving voltage for driving the galvano actuator; a cable connecting the drive unit and the galvano actuator, The cable is a low inductance cable. A laser processing device characterized by:

2. The low inductance cable is a coaxial cable, a twisted pair cable, or a parallel plate structure power supply line.

2. The laser processing device according to claim 1.

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