Actuator driving device and laser processing device

Abstract

To prevent a decrease in the operating accuracy of an actuator even when the power supply voltage changes.SOLUTION: A driving device (100) for an actuator (6A), in which a drive signal voltage (VO) is applied to one of a positive terminal (6Aa) and a negative terminal (6Ab), and a voltage (VN) of a power supply (32) is applied to the other, includes: an amplifier (121) configured to input the power supply voltage and a control signal voltage (VC) for controlling the actuator, amplify the control signal voltage at a predetermined ratio using the power supply voltage, and generate the drive signal voltage (VO) to be output to the actuator; and a level shift circuit (130) configured to input the control signal voltage from a control unit (10), shift it at a predetermined ratio according to changes in the power supply voltage, and output it to the amplifier. The driving signal voltage is output such that the fluctuation range of the drive signal voltage is made equivalent to the fluctuation range of the input control signal voltage, even though the power supply voltage is a first voltage or a second voltage higher than the first voltage.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an actuator driving device that outputs a driving signal voltage obtained by amplifying a control signal voltage to the actuator, and to a laser processing device. [Background technology]

[0002] For example, some laser processing devices, which irradiate printed circuit boards with laser light to perform drilling, use actuators such as piezoelectric elements to drive polygon mirrors, thereby deflecting the irradiation position of the laser light and controlling the irradiation position of the laser light on the printed circuit board (see Patent Document 1).

[0003] In an actuator driving device that drives and controls such an actuator, a control signal voltage (hereinafter referred to as "control signal voltage") is amplified by a class D amplifier using the voltage of a power supply, and the amplified voltage is output to the actuator as a drive signal voltage (hereinafter referred to as "drive signal voltage"). Specifically, as shown in FIG. 3, in a conventional actuator driving device 200, a control signal voltage VC output from a control unit 10 is amplified by a class D amplifier 221 of an actuator driving circuit 220 using voltages VP and VN of power supplies 31 and 32, to generate a drive signal voltage VO, which is output to actuator 6A. For example, if the control signal voltage VC varies within a range of +1V to -1V and the gain of the class D amplifier 221 is set to 50 times, the drive signal voltage VO output from the class D amplifier varies within a range of -50V to +50V (when the gain is A, this can be expressed mathematically as "VO = VC × (-A)").

[0004] The positive terminal 6Aa of the actuator 6A is connected to the output terminal 221e of the class-D amplifier 221, and the negative terminal 6Ab is connected to the negative side of the power supply 32, to which a voltage VN is applied. As a result, the applied voltage VL applied to the actuator 6A can be expressed mathematically as "VL = VO + VN = VC × A + VN." That is, the control signal voltage VC varies within a range of +1 V to -1 V, and the drive signal voltage VO varies within a range of -50 V to +50 V, so that the applied voltage VL of the actuator 6A varies within a range of 0 V to +100 V. In other words, the control unit 10 can vary the applied voltage VL of the actuator 6A within a range of 0 V to +100 V by varying the control signal voltage VC within a range of +1 V to -1 V. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-94122 Summary of the Invention [Problem to be solved by the invention]

[0006] In the actuator driver 200 described above, the drive signal voltage V0 is amplified using the voltage VN of the power supply 32, and the voltage VN of the power supply 32 is applied to the actuator 6A. Therefore, the applied voltage VL of the actuator 6A is affected by fluctuations in the voltage VN of the power supply 32. The output voltage of a typical power supply device is subject to error factors, such as initial setting accuracy, load fluctuations, input voltage fluctuations, temperature fluctuations, time drift, and aging. For example, if the voltage VN of the power supply 32 changes from 50 V to 51 V due to the above error factors, the applied voltage VL of the actuator 6A will change by +1 V, even though the control signal voltage VC remains unchanged. Thus, in the conventional actuator driver 200, the operation of the actuator 6A is affected by changes in the voltage VN of the power supply 32, resulting in a problem of reduced operational accuracy. This, in turn, results in a problem of reduced machining accuracy in the laser machining device.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an actuator driving device and a laser processing device that are capable of preventing a decrease in the operating accuracy of the actuator even when the voltage of the power supply changes. [Means for solving the problem]

[0008] One aspect of the present invention is an actuator driving device comprising: an amplifier that receives a power supply voltage as input and a control signal voltage for controlling an actuator, amplifies the control signal voltage by a predetermined ratio using the power supply voltage, and generates a drive signal voltage to be output to the actuator; and a level shift circuit that shifts the control signal voltage input from a control unit by the predetermined ratio in accordance with changes in the power supply voltage and outputs the shifted control signal voltage to the amplifier, wherein whether the power supply voltage is a first voltage or a second voltage higher than the first voltage, the drive signal voltage is output with a fluctuation range that is equivalent to the fluctuation range of the input control signal voltage. [Effects of the Invention]

[0009] According to the present invention, it is possible to prevent the operational accuracy of the actuator from decreasing even when the voltage of the power supply changes. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing a laser processing device according to an embodiment of the present invention; [Figure 2] FIG. 2 is a schematic diagram showing a driving device for the actuator according to the present embodiment. [Figure 3] FIG. 1 is a schematic diagram showing a conventional actuator driving device. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment for carrying out the present invention will be described below with reference to Figures 1 and 2. Figure 1 is a schematic diagram showing a laser processing device according to this embodiment, and Figure 2 is a schematic diagram showing a drive device for an actuator according to this embodiment.

[0012] [Schematic configuration of laser processing equipment] The laser processing apparatus 1 according to this embodiment will be described with reference to Fig. 1. As shown in Fig. 1, the laser processing apparatus 1 includes a control unit 10, an actuator drive circuit 120 (described in detail below), an actuator 6A, a mirror 3, and a processing table 2, and drills a workpiece W placed on the processing table 2 with a laser beam L.

[0013] In detail, the control unit 10 controls the execution of the entire processing operation of the laser processing device 1, and in particular, the control unit 10 controls the laser irradiation position on the workpiece W by driving and controlling the actuator 6A via the actuator driving circuit 120 based on the given laser irradiation position information, and controlling the posture (angle) of the mirror 3 that reflects the laser light L.

[0014] Although the actuator 6A is shown as a single unit in FIG. 1, it is arranged, for example, so as to contact three points on the mirror 3, and is configured so that the angle of the reflective surface of the mirror 3 can be freely controlled. Therefore, it is preferable to provide three actuator drive circuits 120 corresponding to the actuators 6A. Each actuator 6A is provided with a piezoelectric element (not shown), and the mirror 3 is driven by applying a drive signal (drive signal voltage VO) from the actuator drive circuit 120 in response to a control signal (control signal voltage VC described later) output from the control unit 10. The mirror 3 driven in this manner polarizes the laser light L, and controls the position in the X and Y directions at which the laser light L is irradiated onto the workpiece W.

[0015] The relationship between the irradiation position on the workpiece W and the control signal voltage VC for applying the drive signal voltage VO to the piezoelectric element of the actuator 6A is stored as table information in a storage means (not shown), and by determining the irradiation position in the control unit 10, information on the control signal voltage VC corresponding to that irradiation position is read out and output from the control unit 10. As a result, the laser light is irradiated onto the desired irradiation position on the workpiece W, and the workpiece W is drilled.

[0016] [Configuration of actuator drive device] Next, the configuration of the actuator driving device 100 according to this embodiment will be described with reference to Fig. 2. As shown in Fig. 1, the actuator driving device 100 generally includes an actuator driving circuit 120 arranged so as to be interposed between the control unit 10, power sources 31 and 32, and the actuator 6A.

[0017] The actuator drive circuit 120 has a control signal input terminal 120a that inputs a control signal voltage VC (positive voltage VC_P of the control signal voltage VC) for driving and controlling the actuator 6A from the control unit 10, a ground terminal 120b that is connected to the ground voltage of the control unit 10 (negative voltage VC_N of the control signal voltage VC), a positive voltage input terminal 120c that is connected to the positive terminal of the power supply 31, a negative voltage input terminal 120d that is connected to the negative terminal of the power supply 32, a ground terminal 120e that is connected to the ground terminal 120b and to a ground portion between the power supplies 31 and 32, and a drive signal output terminal 120f that outputs a drive signal voltage VO.

[0018] That is, the power supply 31 that supplies the voltage VP has its positive side connected to the positive voltage input terminal 120c and its negative side connected to the ground terminal 120e. Furthermore, the power supply 32 that supplies the voltage VN has its positive side connected to the ground terminal 120e and its negative side connected to the negative voltage input terminal 120d and the negative terminal 6Ab of the actuator 6A. That is, the voltage at the negative voltage input terminal 120d of the actuator drive circuit 120 is the negative voltage VO_N of the drive signal voltage VO applied to the actuator 6A. The positive terminal 6Aa of the actuator 6A is connected to the drive signal output terminal 120f of the actuator drive circuit 120. That is, the voltage at the positive terminal 6Aa of the actuator 6A is the positive voltage VO_P of the drive signal voltage VO applied to the actuator 6A.

[0019] The actuator drive circuit 120 is configured to include a class D amplifier (class D amplifier) ​​121 as a switching amplifier, and a level shift circuit 130. The class D amplifier 121 includes a control signal input terminal 121a as a control signal input unit to which a control signal voltage VC is input via the level shift circuit 130, a positive voltage input terminal 121b connected to the positive side of the power supply 31 via the positive voltage input terminal 120c, a negative voltage input terminal 121c connected to the negative side of the power supply 32 via the negative voltage input terminal 120d, a ground terminal 121d connected to the ground voltage of the control unit 10 via the ground terminal 120b, and a drive signal output terminal 121e that outputs a drive signal voltage VO to the positive terminal 6Aa of the actuator 6A via the drive signal output terminal 120f. That is, the class D amplifier 121 receives the voltages VP and VN of the power supplies 31 and 32 as input, as well as the control signal voltage VC for controlling the actuator 6A, amplifies the control signal voltage VC at a predetermined ratio (gain A) using the voltages VP and VN of the power supplies 31 and 32, and generates the drive signal voltage VO to be output to the actuator 6A.

[0020] The level shift circuit 130 has a control signal input terminal 130a as a control signal input unit that inputs a control signal voltage VC via the control signal input terminal 120a, a negative voltage input terminal 130b as a power supply voltage input unit that is connected to the negative side of the power supply 32 via the negative voltage input terminal 120d, a control signal output terminal 130c as a control signal output unit that outputs a control signal voltage VC shifted at a predetermined ratio to the control signal input terminal 121a of the class D amplifier 121, as will be described in detail later, and a ground wiring 130g as a ground unit that is connected to the ground terminal 120b (and the ground terminal 120e).

[0021] The level shift circuit 130 also includes a voltage divider circuit 131 that is interposed between the negative voltage input terminal 130b and the ground wiring 130g and outputs a voltage that is divided at a predetermined ratio between the voltage -VN of the power supply 32 and the ground (i.e., 0V), a buffer circuit 132 that is connected to the voltage divider circuit 131 and outputs the divided voltage -VN2 as a buffer output voltage, and an arithmetic circuit 133 that adds the control signal voltage VC and the buffer output voltage -VN2 to generate a shifted control signal voltage VA.

[0022] The voltage-dividing circuit 131 is configured with a first resistor R1 and a second resistor R2 connected in series between the negative voltage input terminal 130b and the ground wiring 130g, and the ratio between the resistance values ​​of the first resistor R1 and the second resistor R2 is set to be the same as the gain A (predetermined ratio) of the class-D amplifier 121. The buffer circuit 132 is configured with a first operational amplifier OP1 that corrects and outputs the voltage of the power supply 32 divided by the voltage-dividing circuit 131. The arithmetic circuit 133 is configured with a third resistor R3 connected to the control signal input terminal 130a, a fourth resistor R4 connected to the first operational amplifier OP1, a second operational amplifier OP2 connected to the third resistor R3 and the fourth resistor R4 and also connected to the ground wiring 130g, and a fifth resistor R5 connected in parallel to the second operational amplifier OP2.

[0023] [Operation of the actuator drive unit] Next, the operation of the actuator drive device according to the first embodiment will be described. As described above, the first resistor R1 and the second resistor R2 form the voltage divider circuit 131 that divides the voltage −VN of the power supply 32 at a voltage division ratio of 1 / B (i.e., a predetermined ratio).

[0024] This voltage division ratio B is expressed by the following equation (1).

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[0025] The divided voltage is output through a buffer circuit 132 formed by a first operational amplifier OP1, and the output voltage −VN2 is given by the following equation (2).

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[0026] The third resistor R3, the fourth resistor R4, the fifth resistor R5, and the second operational amplifier OP2 constitute an arithmetic circuit 133 that adds the control signal voltage VC and the buffer output voltage −VN2. The shifted control signal voltage VA, which is the output voltage of the second operational amplifier OP2, is given by the following equation (3):

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[0027] On the other hand, the class D amplifier 121 amplifies the shifted control signal voltage VA output by the second operational amplifier OP2 by a gain of −A. The output Vo of the class D amplifier is given by the following equation (5).

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[0028] Furthermore, from equations (4) and (5), the drive signal voltage VO output by the class D amplifier 121 is given by the following equation (6).

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[0029] The positive terminal 6Aa of the actuator 6A is connected to the drive signal output terminal 121e of the class-D amplifier 121, and the negative terminal 6Ab is connected to the negative terminal of the power supply 32, so that the drive signal voltage VO and the voltage -VN of the power supply 32 are applied to the actuator 6A. Therefore, the applied voltage VL of the actuator 6A is given by the following equation (7).

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[0030] Furthermore, from the above equations (6) and (7), the voltage VL applied to the actuator 6A is given by the following equation (8).

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[0031] Therefore, if the third resistor R3, the fourth resistor R4, and the fifth resistor R5 are set to the same resistance value (R3=R4=R5) and the gain A of the class D amplifier 121 and the voltage division ratio B of the voltage divider circuit 131 are set to the same predetermined ratio (A=B), the effect of changes in the voltage VN of the power supply 32 on the applied voltage VL of the actuator 6A can be canceled.

[0032] A specific example is as follows: For example, if R3=R4=R5=1 [KΩ], A=50, R1=1 [KΩ], and R2=49 [KΩ], then the voltage division ratio B is 50 according to equation (1), and the relationship A=B is established.

[0033] By substituting these values ​​into equation (8), the voltage VL applied to the actuator 6A is given by the following equation (9).

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[0034] [Summary of this embodiment] As described above, the applied voltage VL of the actuator 6A is not affected by fluctuations in the voltage VN of the power supply 32, and the actuator 6A can be controlled by the control signal voltage VC without recalculating the control signal voltage VC. In other words, even if the voltage VN of the power supply 32 changes for some reason from a first voltage (50V) to a second voltage (51V), the actuator driver 100 can output a drive signal voltage VO with a fluctuation range (e.g., −50V to 50V) equivalent to the fluctuation range of the input control signal voltage VC (e.g., −1V to 1V), regardless of the voltage change of the power supply 32. Therefore, it is possible to provide an actuator driver 100 that is not affected by the initial setting accuracy of the voltage VN of the power supply 32, load fluctuations, input voltage fluctuations, temperature fluctuations, time drift, aging, etc. In short, the actuator driver 100 can prevent a decrease in the operational accuracy of the actuator 6A even when the voltage VN of the power supply 32 changes.

[0035] Even if the voltage of the power supply 32 changes in this way, the drive signal voltage VO is stable relative to the control signal voltage VC, so the actuator 6A can be controlled with high precision, and a laser processing device 1 equipped with this can perform drilling with high precision.

[0036] [Possibilities for other embodiments] In the above-described embodiment, the actuator 6A is described as driving the galvanometer scanner 6 in the laser processing apparatus, but the present invention is not limited to this and may be an actuator for driving any object, such as a mirror or a lens. In particular, the driving device 100 of this actuator is not limited to being mounted on the laser processing apparatus 1, and may be mounted on other devices such as machine tools.

[0037] Furthermore, in this embodiment, a class D amplifier (switching amplifier) ​​is used for the actuator driving device 100, but this is not limiting and any amplifier may be used, for example, a linear amplifier configured with a bipolar transistor or a MOS-FET.

[0038] In addition, in this embodiment, the drive signal voltage is input to the positive terminal 6Aa of the actuator 6A, and the voltage VN of the power supply 32 is applied to the negative terminal 6Ab. However, for example, the negative terminal 6Ab may be connected to ground, or the terminals may be connected so that the positive and negative polarities are reversed. When applying the voltage VN of the power supply 32 to the actuator 6A, it does not matter whether it is applied to the positive terminal or the negative terminal; in other words, it is sufficient that the drive signal voltage is applied to one of the positive terminal and the negative terminal of the actuator, and the power supply voltage is applied to the other. [Explanation of symbols]

[0039] 3...laser oscillator / 6...galvanometer scanner (deflection section) / 6A...actuator / 6Aa...positive terminal / 6Ab...negative terminal / 10...control section / 32...power supply / 100...actuator driver / 121...class D amplifier (amplifier) ​​ / 130...level shift circuit / 130a...control signal input terminal (control signal input section) / 130b...negative voltage input terminal (power supply voltage input section) / 130c...control signal output terminal (control signal output section) / 130g...ground wiring (ground section) / 131...voltage divider circuit / 132...buffer circuit / 133...arithmetic circuit / VA...shifted control signal voltage / VC...control signal voltage / VN...power supply voltage / VN2...buffer output voltage / VO...drive signal voltage

Claims

1. an amplifier that receives a power supply voltage and a control signal voltage for controlling an actuator, amplifies the control signal voltage at a predetermined ratio using the power supply voltage, and generates a drive signal voltage to be output to the actuator; a level shift circuit that shifts the control signal voltage input from the control unit at the predetermined ratio in response to a change in the voltage of the power supply and outputs the shifted control signal voltage to the amplifier; whether the voltage of the power supply is a first voltage or a second voltage higher than the first voltage, the fluctuation range of the drive signal voltage is made equal to the fluctuation range of the input control signal voltage and is output. A driving device for an actuator characterized by:

2. The actuator has a positive terminal and a negative terminal to which the drive signal voltage is applied and to which the power supply voltage is applied.

2. The actuator driving device according to claim 1.

3. The level shift circuit includes: a control signal input unit for inputting the control signal voltage; a power supply voltage input unit for inputting the voltage of the power supply; a ground portion connected to the ground; a control signal output unit that outputs the shifted control signal voltage; a voltage dividing circuit interposed between the power supply voltage input section and the ground section, and outputting a voltage divided at the predetermined ratio; a buffer circuit connected to the voltage divider circuit and outputting the divided voltage as a buffer output voltage; an arithmetic circuit that adds the control signal voltage and the buffer output voltage to generate the shifted control signal voltage; 2. The actuator driving device according to claim 1.

4. The actuator drive device according to claim 1; a laser oscillator that emits laser light; The control unit; the actuator; a deflection unit that is driven by the actuator and deflects the laser light by being driven by the actuator, A laser processing device characterized by:

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