JP4962508B2 - Laser processing apparatus and pulse signal output method for laser driving in laser processing apparatus - Google Patents

Description

The present invention sets a plate-like workpiece on a table, rotates it, irradiates the workpiece with pulsed laser light, and moves the irradiation position of the laser light in the radial direction of the table. The present invention relates to a laser processing apparatus that forms a processing trace (pit or reaction trace) in a spiral shape on the surface of an object. The present invention also relates to a method for outputting a laser driving pulse signal supplied to a laser light source in order to irradiate a laser beam in the laser processing apparatus.

Conventionally, a flat workpiece is set on a table and rotated to irradiate the workpiece with laser light, and the laser beam irradiation position is moved in the radial direction of the table to thereby move the surface of the workpiece. There is known a laser processing apparatus that performs laser processing on a spiral . When forming a plurality of pits or reaction traces for forming pits (hereinafter collectively referred to as pits) over the entire surface of the workpiece, for example, as proposed in Patent Document 1, A pulse signal (laser driving pulse signal) is supplied to a laser light source which is an emission source to irradiate a pulsed laser beam.

  Such laser processing by pulsed laser light irradiation is used, for example, when an LED substrate is formed. An LED is formed by stacking thin films on a substrate by chemical vapor deposition. By forming irregularities on the surface of the substrate, the LED has a light extraction ratio that can be extracted to the outside with respect to the light generated in the light emitting layer. Light extraction efficiency can be improved. For this reason, fine pits are formed on the substrate by pulsed laser light irradiation, and the entire surface of the substrate is processed to be uneven.

  When pits are formed on an LED substrate, for example, the rotation of the table is controlled so that the irradiation position of the laser beam is constant, and the pit interval and linear velocity are set with the period of the pulse signal for laser driving. If the distance that the irradiation position of the laser beam moves in the radial direction during one rotation of the table is set to the same value as the pit interval, the circumferential pit interval and the radial pit interval are And the pits can be arranged uniformly over the entire substrate surface.

JP 2007-216263 A

  However, in this method, when the irradiation position of the laser beam changes in the radial direction, the movement distance in the circumferential direction of the laser spot when the table rotates once also changes. As shown in the figure, even if the intervals of the pits P are the same, the pits P are not arranged so as to be at a square vertex position (intersection position of graph paper). Hereinafter, the arrangement of pits refers to an arrangement captured in a minute area.

  According to research by manufacturers who produce LED substrates, it is said that the light extraction efficiency varies depending on the arrangement of pits. Then, the light extraction efficiency is higher in the case where the pits P are arranged at the apexes of the square as shown in FIG. 7B than in the case where the pits P are arranged as shown in FIG. It is said that it tends to become.

  In order to arrange the pits so as to be at the apex position of the square, the rotation of the table is controlled at a constant angular velocity, and the period of the pulse signal for laser driving supplied to the laser light source is the timing at which the table rotates exactly once. A method of setting the pulse signals to have the same phase is conceivable. However, in this method, the linear velocity changes depending on the radial position of the laser beam irradiation position (distance from the rotation center of the table), so that the pit shape changes. Further, the pit interval in the circumferential direction also changes depending on the radial position.

  A method of controlling the rotation of the table at a constant linear velocity and modulating the laser driving pulse signal in synchronization with the rotation of the table is also conceivable, but this method increases the cost because the circuit configuration is complicated. Become. Further, the pit interval in the circumferential direction changes depending on the radial position of the laser light irradiation position.

  The present invention has been made in order to address the above-described problem, and provides a laser processing apparatus and a pulse signal output method for driving a laser in the laser processing apparatus capable of forming pits in an appropriate arrangement over the entire processing region of a processing target. It is to provide.

In order to achieve the above object, the present invention is characterized in that a table for setting a flat plate-like workpiece, a rotating means for rotating the table, and a workpiece on the workpiece set and rotated on the table are rotated. A radius that moves the irradiation position of the laser beam on the object to be processed in the radial direction of the table by changing a relative position between the machining head having a laser light source for irradiating light and the machining head and the table. Direction irradiation position moving means and laser driving for outputting a laser driving pulse signal to the laser light source, intermittently emitting laser light from the laser light source, and forming processing marks on the surface of the processing object at predetermined intervals Means, a radial position detecting means for detecting a radial position representing a distance from a rotation center of the table to an irradiation position of the laser beam, and the table. Based on a rotation signal output means for outputting a rotation detection signal each time the rod rotates by a predetermined angle, a radial position detected by the radial position detection means, and a rotation detection signal output by the rotation signal output means. A laser processing apparatus comprising: a rotation speed control means for controlling the rotation speed of the rotation means so that the linear velocity at the irradiation position of the laser light is a constant set speed;
Reference rotation position detecting means for detecting the reference rotation position every time the table rotates and reaches a preset reference rotation position, and a circumferential interval for setting a circumferential interval between machining marks formed on the workpiece. The setting means and the number of circumferential directions of the processing trace formed when the table rotates once are made the same in the inner and outer circumferences adjacent to each other in the laser beam irradiation locus, and the reference rotation For each laser beam irradiation position movement interval from the position until the next reference rotation position is detected, the circumferential interval is set based on the movement distance of the laser beam irradiation position in the irradiation position movement interval A circumferential interval correction unit that calculates a corrected circumferential interval by correcting a circumferential interval of the machining trace set by the unit, and the circumferential interval correction for each irradiation position movement section of the laser beam A pulse period calculating means for calculating a period of the laser driving pulse signal based on the corrected circumferential interval calculated by the stage and the constant linear velocity, and outputting the laser driving pulse signal of the calculated period Pulse signal information storage means for storing pulse signal information for driving, and at the time of laser processing, the laser drive at a cycle according to the irradiation position movement section of the laser light according to the pulse signal information stored in the pulse signal information storage means And a laser drive control means for outputting a laser drive pulse signal from the means.

The laser processing apparatus of the present invention includes a processing head having a laser light source, rotates the table in a state where the processing object is set (fixed) on the table, and irradiates the surface of the rotating processing object with laser light. Laser processing. The irradiation position of the laser beam is also moved in the radial direction of the table by the radial direction irradiation position moving means. Therefore, the irradiation locus of the laser beam on the object to be processed has a spiral shape . The laser light source is operated by a laser driving pulse signal output from the laser driving means, and intermittently emits laser light synchronized with the laser driving pulse signal. Therefore, processing marks are formed on the surface of the processing object at predetermined intervals. The processing trace means a pit (concave portion) or a reaction trace in which a pit is formed by post-processing with a developer or the like.

  During laser processing, the radial position detection means detects a radial position representing the distance from the rotation center of the table to the irradiation position of the laser beam, and the rotation signal output means rotates the table by a predetermined angle (a minute set angle). The rotation detection signal is output to. The rotation angle of the table can be detected from this rotation detection signal. The rotation speed control unit controls the rotation speed of the rotation unit based on the radial position and the rotation detection signal so that the linear velocity at the irradiation position of the laser light becomes a constant set speed.

  In the laser processing apparatus of the present invention, the reference rotation position of the table is set in advance, and the reference rotation position detecting means detects that the table has rotated and reached the reference rotation position. In performing laser processing, it is necessary to set the circumferential interval of the machining trace in advance, and the circumferential interval of the machining trace is set by the circumferential interval setting means. For example, an operator inputs circumferential interval information using an input device, and the circumferential interval is set by storing the information.

In order to arrange the processing traces in an appropriate positional relationship between the inner circumference and the outer circumference adjacent to each other in the laser beam irradiation trajectory, the number of circumferential directions of the machining traces formed when the table rotates once is adjacent to the inner circumference. Must be the same on the outer circumference and the outer circumference. In this case, the irradiation trajectory of the laser beam has a spiral shape, and therefore the circumference is different between the inner circumference and the outer circumference. Therefore, the circumferential interval correction means moves the irradiation position of the laser light irradiation position in the irradiation position movement section for each irradiation position movement section of the laser light from the reference rotation position until the next reference rotation position is detected. Based on the above, the circumferential interval of the machining trace set by the circumferential interval setting means is corrected. By correcting the circumferential interval, it is possible to set the circumferential interval of the machining trace according to the difference in the circumferential length.

  Then, the pulse period calculation means is based on the corrected circumferential interval calculated by the circumferential interval correction means and the linear velocity (constant) controlled by the rotation speed control means for each irradiation position movement section of the laser beam. The period of the laser driving pulse signal is calculated, and the pulse signal information storage means stores pulse signal information for outputting the laser driving pulse signal of the calculated period. Since the cycle and frequency of the pulse signal are reciprocal, calculating the cycle includes calculating the frequency.

  After the pulse signal information is stored in this way, laser processing is performed. Alternatively, laser processing is performed while storing pulse signal information of a region where laser processing will be performed in the future. At the time of laser processing, the laser drive control means causes the laser drive means to output a laser drive pulse signal at a cycle according to the irradiation position movement section of the laser light in accordance with the pulse signal information stored in the pulse signal information storage means. . For example, the laser drive control means outputs, to the laser drive means, a pulse signal having a period specified by the pulse signal information corresponding to the laser light irradiation position movement section every time the reference rotation position is detected. Then, the laser driving means converts the input pulse signal into a laser driving pulse signal and outputs it to the laser light source.

  As a result, the arrangement of the processing traces can be maintained in an appropriate relationship between the adjacent inner circumference and outer circumference in the laser beam irradiation locus. Therefore, the processing traces can be evenly arranged over the entire processing region of the processing object. For example, the processing marks can be arranged so as to be at the apex position of the square, or can be arranged in a staggered manner. Thereby, for example, when unevenness is formed on the substrate of the LED using the laser processing apparatus of the present invention, an LED with high light extraction efficiency can be manufactured.

  Another feature of the present invention is that the circumferential interval correction unit allows a difference between a circumferential interval of the machining trace set by the circumferential interval setting unit and a corrected circumferential interval corrected for the circumferential interval. When the value exceeds the value, the number in the circumferential direction of the machining marks formed when the table rotates once is changed so that the difference falls within an allowable value.

  When the irradiation position of the laser beam is moved in the radial direction, the circumferential length of the irradiation path of the laser beam when the table rotates once changes gradually, so that the process formed when the table rotates once. When the number of traces in the circumferential direction is the same, the difference between the preset circumferential interval of the machining trace and the corrected corrected circumferential interval gradually increases. Therefore, in the present invention, when the difference between the circumferential interval of the machining trace set by the circumferential interval setting means and the corrected circumferential interval obtained by correcting the circumferential interval exceeds an allowable value, the irradiation position movement is performed. From the section, the number of machining traces formed when the table rotates once is changed so that the difference falls within the allowable value. Thereby, the difference from the circumferential direction space | interval of the preset processing trace can be maintained in an allowable range.

  When the number of machining traces in the circumferential direction is changed, the machining traces cannot be placed in an appropriate relationship in the adjacent circumference of the laser beam irradiation locus at the time of the change. Since the amount of change in the radial position that moves when the table rotates once with respect to the radial position of the laser beam is set to be extremely small, the circumference of the laser beam irradiation locus with respect to the change in the radial position of the laser beam irradiation position There is very little change. For this reason, the frequency of changing the number of processing marks in the circumferential direction is low, and the processing marks can be formed in an appropriate arrangement when viewed as the entire processing region of the processing object.

  Another feature of the present invention is that the circumferential interval correction unit is configured to determine, for each irradiation position movement section of the laser beam, a movement distance of the irradiation position of the laser beam in the irradiation position movement section by the circumferential interval setting unit. The purpose is to calculate a corrected circumferential interval by correcting the circumferential interval of the machining trace set by the circumferential interval setting means so that no remainder is generated when dividing by the circumferential interval of the set machining trace. .

  According to the present invention, since the processing trace can be arranged on a straight line starting from the rotation center of the table, the processing trace is arranged to be a square or rectangular vertex position when captured in a minute region. Can do. In this case, during one rotation of the table, the irradiation position of the laser beam moves in the radial direction of the table by the same distance as the circumferential interval of the machining trace set by the circumferential interval setting means or the corrected corrected circumferential interval. Thus, by providing the radial direction movement control means for controlling the radial direction irradiation position moving means, it is possible to arrange the processing traces so as to be the vertex positions of the square.

  Another feature of the present invention is that the laser drive control means has a low level after a set time shorter than a low level time width of the laser drive pulse signal has elapsed since the reference rotational position was detected. The laser driving means is controlled to output a laser driving pulse signal that changes from high to low.

  Since the laser driving pulse signal in the present invention is output at a cycle corresponding to the irradiation position moving section of the laser beam, the pulse signal for the laser driving is switched to a new cycle every time the reference rotation position is detected. When this reference rotation position is detected, if a laser drive pulse signal having a new period is output from a high level immediately after that, the influence of the rotation jitter of the table may appear in the machining trace shape. For example, if the pulse signal for laser drive is at a high level immediately before the reference rotation position is detected due to the effect of table rotation jitter, laser drive with a new period is detected when the reference rotation position is detected. When the pulse signal for output is output at a high level, the high level period continues across the reference rotation position, and the shape of the machining trace is destroyed.

  Therefore, in the present invention, the laser drive control means changes from the low level to the high level after a set time shorter than the low level time width of the laser drive pulse signal has elapsed since the reference rotational position was detected. Since the laser driving means is controlled so as to output the laser driving pulse signal to be outputted, it is possible to prevent the shape of the machining trace from being damaged by the rotational jitter.

  Another feature of the present invention resides in that the reference rotation position detection means detects a plurality of reference rotation positions set in one rotation of the table.

  In the present invention, since a plurality of reference rotation positions are set for one rotation of the table, the influence of rotation jitter is suppressed, and processing traces can be formed with a more accurate arrangement.

  In another feature of the present invention, the reference rotation position detecting unit detects a reference rotation position once in one rotation of the table, and the circumferential interval correction unit is configured to irradiate the laser beam in the irradiation position moving section. In order not to generate a remainder when a distance obtained by adding a distance that is a half of the circumferential distance of the set machining trace to the movement distance of the position is divided by the circumferential interval of the set machining trace, A corrected circumferential interval obtained by correcting the circumferential interval of the set machining trace is calculated, and the laser drive control means is configured to detect the laser drive pulse signal every other time when the reference rotation position is detected. Is to control the laser driving means so as to shift the timing of starting the output of ½ by one half of the calculated period of the pulse signal.

  According to the present invention, a processing trace can be formed at an intermediate position between adjacent processing traces in a laser beam irradiation trace. Therefore, the processing marks can be arranged in a staggered pattern on the surface of the processing object. In this case, during one rotation of the table, the laser beam is irradiated by a distance obtained by multiplying the circumferential interval of the machining trace set by the circumferential interval setting means or the corrected corrected circumferential interval by (√3) / 2. By providing the radial movement control means for controlling the radial irradiation position moving means so that the position moves in the radial direction of the table, it is possible to arrange the intervals between adjacent processing traces in a uniform staggered pattern.

  Furthermore, the implementation of the present invention is not limited to the invention of the laser processing apparatus, but can also be implemented as an invention of a method for outputting a pulse signal for driving a laser in the laser processing apparatus.

1 is a system configuration diagram of a laser processing apparatus according to an embodiment. It is a flowchart showing a pulse signal creation routine. It is a flowchart showing a laser processing control routine. It is a flowchart showing a pulse signal output control routine. It is a table | surface showing the number of pits for every radial position, and correction | amendment circumferential direction pit space | interval. It is explanatory drawing showing the relationship between a pulse signal and a pit. It is an arrangement drawing showing arrangement of a pit formed in a processing object. It is an arrangement drawing showing arrangement of a pit formed in a processing object. It is explanatory drawing showing the relationship between a pulse signal and a pit. It is a flowchart showing the pulse signal output control routine as a modification.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic system configuration diagram of a laser processing apparatus 1 according to the embodiment. The laser processing apparatus 1 includes a table 21 as a support member that fixes and supports a flat plate-shaped object OB, and a processing head 30 that irradiates a laser beam toward the object OB and laser-processes the object OB. And. The processing object OB is used as an LED substrate by forming innumerable nano-sized ultra-fine pits on the surface by the laser light emitted from the processing head 30. The table 21 is formed in a disk shape and is driven by a spindle motor 22 and a feed motor 23. The processing head 30 is fixed by a head support frame (not shown) fixed to the apparatus main body.

  The spindle motor 22 rotationally drives the table 21 through the rotation shaft 22b by the rotation. The spindle motor 22 incorporates an encoder 22a that detects the rotation of the motor 22, that is, the table 21, and outputs a rotation signal representing the rotation. This rotation signal includes an index signal generated every time the rotation position of the table 21 reaches one reference rotation position, and a pulse train that alternately switches between a high level and a low level every time the table 21 rotates by a predetermined minute angle. Signal. The index signal is used to detect the reference rotational position of the table 21. The pulse train signal is used to detect the rotation angle of the table, and is composed of an A-phase signal and a B-phase signal that are out of phase with each other by π / 2 in order to identify the rotation direction. This pulse train signal corresponds to the rotation detection signal of the present invention. Hereinafter, the pulse train signal output from the encoder 22a is referred to as a rotation detection pulse train signal.

  The index signal is supplied to the pulse signal supply device 50 and the controller 90, and the rotation detection pulse train signal is supplied to the spindle motor control circuit 53. The spindle motor control circuit 53 starts to operate in response to a rotation speed instruction from the controller 90, calculates the rotation speed of the spindle motor 22 based on the number of pulses per unit time of the rotation detection pulse train signal output from the encoder 22a, and calculates The rotation of the spindle motor 22 is controlled so that the rotation speed becomes equal to the rotation speed instructed by the controller 90.

  The feed motor 23 rotates the screw rod 24 to drive the table 21 in the radial direction. The screw rod 24 is connected to one end of the screw rod 24 so as to rotate integrally with the rotation shaft of the feed motor 23, and is screwed to a nut (not shown) fixed to the support member 25 at the other end. The support member 25 fixedly supports the spindle motor 22 and is only allowed to move in the radial direction of the table 21. Therefore, when the feed motor 23 rotates, the spindle motor 22, the table 21, and the support member 25 are displaced in the radial direction of the table 21 by the feed screw mechanism 20 including the screw rod 24 and the nut. The movement direction of the table 21 is set so that a straight line representing the movement locus of the rotation center of the table 21 passes through the irradiation position of the processing head 30.

  Also incorporated in the feed motor 23 is an encoder 23a that detects the rotation of the feed motor 23 and outputs a rotation detection pulse train signal similar to the encoder 22a. The rotation detection pulse train signal output from the encoder 23 a is output to the feed motor control circuit 54 and the radial position detection circuit 52. The radial position detection circuit 52 counts up or down the number of pulses of the rotation detection pulse train signal from the encoder 23a according to the rotation direction of the feed motor 23, and the radial direction of the table 21 to which the laser beam is irradiated from the count value. A feed position (hereinafter referred to as a radial position) is detected, and a signal representing the radial position is output to the controller 90. The initial setting of the count value in the radial position detection circuit 52 is performed by an instruction from the controller 90 when the power is turned on.

  That is, the controller 90 instructs the feed motor control circuit 54 to move the support member 25 to the initial position and the radial position detection circuit 52 when the power is turned on. In response to this instruction, the feed motor control circuit 54 rotates the feed motor 23 to move the support member 25 to the initial position. This initial position is a drive limit position of the support member 25 driven by the feed motor 23. The radial position detection circuit 52 continues to input the rotation detection pulse train signal from the encoder 23a while the support member 25 is moving. When the support member 25 reaches the initial position and the rotation of the feed motor 23 stops, the radial position detection circuit 52 detects the stop of the rotation detection pulse train signal from the encoder 23a and sets the count value to “0”. Reset. At this time, the radial position detection circuit 52 outputs a signal for stopping the output to the feed motor control circuit 54, whereby the feed motor control circuit 54 stops outputting the drive signal to the feed motor 23. Thereafter, when the feed motor 23 is driven, the radial position detection circuit 52 counts up or down the number of pulses of the rotation detection pulse train signal according to the rotation direction of the feed motor 23, and based on the count value. Then, the radial position which is the feed position of the table 21 in the radial direction is calculated, and a signal representing the radial position is continuously output to the feed motor control circuit 54 and the controller 90.

  The feed motor control circuit 54 drives and controls the feed motor 23 according to an instruction from the controller 90 to move the irradiation position of the laser beam to a designated radial position of the table 21 or move the table 21 in the radial direction at a designated speed. Or Specifically, the feed motor control circuit 54 feeds using the radial position detected by the radial position detection circuit 52 when the movement of the irradiation position of the laser beam to the radial position designated by the controller 90 is instructed. The rotation of the motor 23 is controlled, and the feed motor 23 is rotated until the detected radial position becomes equal to the radial position designated by the controller 90. When the feed motor control circuit 54 is instructed to move the irradiation position of the laser beam in the radial direction of the table 21 at the moving speed designated by the controller 90, the feed motor control circuit 54 determines the table from the rotation detection pulse train signal output from the encoder 23a. The movement speed in the radial direction 21 is calculated, and the rotation of the feed motor 23 is controlled so that the calculated movement speed becomes equal to the movement speed designated by the controller 90.

  Next, the processing head 30 will be described. The processing head 30 includes a laser light source 31 and is configured to irradiate laser light emitted from the laser light source 31 toward the processing object OB and to receive the reflected light. The processing head 30 includes a laser light source 31, a collimating lens 32, a polarizing beam splitter 33, a quarter wavelength plate 34, an objective lens 35, a condenser lens 36, a cylindrical lens 37, a photodetector 38, a focus actuator 39, and the like. The laser light emitted from the laser light source 31 passes through the collimating lens 32, the polarizing beam splitter 33, the quarter wavelength plate 34, and the objective lens 35 and is condensed on the surface of the object OB to be processed. Further, the laser beam condensed on the surface of the processing object OB is reflected on the surface of the processing object OB. The reflected light reflected from the surface of the workpiece OB passes through the objective lens 35 and the quarter-wave plate 34, enters the polarization beam splitter 33, is reflected by the polarization beam splitter 33, and enters the condenser lens 36. . The condensing lens 36 condenses the light reflected by the polarization beam splitter 33 on the photodetector 38 via the cylindrical lens 37.

  The laser light source 31 is driven by a laser driving circuit 70. The laser drive circuit 70 starts to operate in response to a command from the controller 90. When a pulse signal is input from the pulse signal supply device 50, the laser drive signal having a pulse train waveform having the same cycle and the same duty ratio as the input pulse signal. Is output to the laser light source 31. The laser drive signal having this pulse train waveform corresponds to the laser drive pulse signal in the present invention. Therefore, the laser light source 31 intermittently emits laser light with the same cycle and the same duty ratio as the pulse signal output from the pulse signal supply device 50 by this laser drive signal. The laser drive circuit 70 outputs a continuous laser drive signal to the laser light source 31 when a DC signal is input from the pulse signal supply device 50. Accordingly, the laser light source 31 continuously emits laser light in response to this laser drive signal.

  When a pulse signal is input from the pulse signal supply device 50, the laser drive circuit 70 outputs a laser drive signal set to the processing intensity, and when a DC signal is input from the pulse signal supply device 50, the laser drive circuit 70 is not processed. Outputs a laser drive signal set to a desired intensity. The processing intensity means that the surface of the workpiece OB is processed by irradiating the surface of the workpiece OB with a laser beam emitted from the laser light source 31 (pits are formed by pit formation or post-processing such as a developing solution). (Reaction traces formed) and the intensity that enables focus servo control. On the other hand, the non-processing intensity means that the surface of the processing object OB is not changed by the irradiation of the laser light emitted from the laser light source 31 onto the surface of the processing object OB (the laser processing is not performed), and It means the strength that enables focus servo control. This non-processing intensity laser beam irradiation is performed when focus servo described later is started.

  The pulse signal supply device 50 has a built-in memory 50a for storing information of a pulse signal output to the laser driving circuit 70. When performing laser processing, the pulse signal supply device 50 inputs a pulse signal cycle T (may be a frequency) and a duty ratio Dy from the controller 90 in advance, and from the cycle T and the duty ratio Dy in the input order. The set pulse signal information is created and stored in the memory 50a. The pulse signal information only needs to be information that can generate a pulse signal (pulse signal with a cycle ratio T and a duty ratio Dy) to be output to the laser drive circuit 70. The pulse signal information includes high-level and low-level time width information and the like. Can do. When a pulse signal output command is input from the controller 90 during laser processing, the pulse signal supply device 50 generates a pulse signal based on pulse signal information stored in the memory 50a by a control process described later, and outputs the pulse signal to the laser drive circuit 70. To do. Further, when a DC signal output command is input from the controller 90, a DC signal is output to the laser driving circuit 70.

  Next, laser beam focus servo will be described. Reflected light from the surface of the workpiece OB of the laser light is received by the photodetector 38. The photodetector 38 is composed of four divided light receiving elements made up of four identical square light receiving elements separated by a dividing line, and the intensity of light incident on the light receiving areas A, B, C, and D arranged in the clockwise direction. A detection signal having a magnitude proportional to is output as a light reception signal (a, b, c, d). The photodetector 38 is fixed so that the reflected light is collected at the center where the four light receiving elements are arranged.

  The received light signals (a, b, c, d) output from the photodetector 38 are input to the HF signal amplifier circuit 61. The HF signal amplification circuit 61 amplifies the received light signals (a, b, c, d) and outputs the amplified signals to the focus error signal generation circuit 62. The focus error signal generation circuit 62 generates a focus error signal by calculation using the amplified light reception signals (a ′, b ′, c ′, d ′). In this embodiment, since the focus servo control by the astigmatism method is used, the calculation of (a ′ + c ′) − (b ′ + d ′) is performed, and the calculation result is used as a focus error signal, and the focus servo circuit 63 Output to. The focus error signal (a ′ + c ′) − (b ′ + d ′) represents the amount of deviation of the focal position of the laser beam from the surface of the workpiece OB.

  The focus servo circuit 63 is controlled in operation by the controller 90, generates a focus servo signal based on the focus error signal, and outputs the focus servo signal to the drive circuit 64. The drive circuit 64 controls the focus actuator 39 according to the focus servo signal to displace the objective lens 35 in the optical axis direction of the laser light. In this case, by generating a focus servo signal so that the value of the focus error signal (a ′ + c ′) − (b ′ + d ′) is always a constant value (for example, zero), the surface of the object OB is processed. The laser beam can be continuously collected.

  The controller 90 is an electronic control device including a microcomputer including a CPU, a ROM, and a RAM, a storage device such as a hard disk and a nonvolatile memory, an input / output interface, and the like. Connected to the controller 90 are an input device 91 for an operator to instruct various parameters, processing, and the like, and a display device 92 for visually informing the operator of inspection results, operating conditions, and the like. .

When performing laser processing, the operator uses the input device 91 to input the following values as laser processing conditions. Instead of the input from the input device 91, a value stored in the memory of the controller 90 may be read out.
Linear velocity: F
Initial radius position: Rf
Circumferential pit interval: Bwt
Radial pit interval: Bwr
End radius position: Re
Duty ratio: Dy

In the laser processing apparatus 1 of the present embodiment, as will be described later, the laser beam is emitted from the laser light source 31 of the processing head 30 in a state where the table 21 on which the processing object OB is set is rotated and moved in the radial direction. Are formed by spirally forming a plurality of ultrafine pits on the surface of the workpiece OB. Therefore, the linear velocity F is a velocity at which the laser spot (irradiation position) moves on the surface of the workpiece OB in the circumferential direction. The initial radius position Rf is the distance from the rotation center of the table 21 of the laser spot when laser processing is started. The circumferential pit interval Bwt is an interval for forming pits in the circumferential direction. The radial pit interval Bwr is the distance between the fine pits in the radial direction, that is, the amount of movement of the laser spot in the radial direction when the laser spot moves on the surface of the workpiece OB by one round. The end radius position Re is a distance from the rotation center of the table 21 of the laser spot when the laser processing is ended. The duty ratio Dy is a duty ratio of a pulse signal output from the pulse signal supply device 50 to the laser driving circuit 70.

  When the operator inputs the laser processing conditions, the operator uses the input device 91 to instruct the controller 90 to start a pulse signal creation routine. FIG. 2 is a flowchart showing a pulse signal creation routine. This pulse signal generation routine is stored as a control program in the ROM of the controller 90, and is started in step S100.

When the pulse signal generation routine is started, the controller 90 sets the value of the variable n to “0” in step S102. Subsequently, in step S104, an integer value N is calculated by the following equation.
N = INT [2π · {Rf + (n + ½) · Bwr} / Bwt]
Here, INT [] means a numerical value obtained by rounding down the decimal point of the solution of the calculation formula in []. Therefore, this integer value N is a numerical value obtained by rounding down the decimal part of 2π · {Rf + (n + ½) · Bwr} / Bwt. That is, in step S104, while the table 21 rotates once, the distance that the laser spot (irradiation position) moves on the surface of the workpiece OB is divided by the circumferential pit interval Bwt, and the decimal part of the solution is rounded down. This is a process for obtaining the integer value. Thus, the number of pits (or the number of pit intervals) to be formed on the workpiece OB during one rotation of the table 21 is obtained. Here, the reason why the radial pit interval Bwr is multiplied by (n + 1/2) is that the laser spot moves spirally on the surface of the workpiece OB. That is, the distance that the laser spot moves until the table 21 rotates once and the radial position of the laser spot changes from Rf + n · Bwr to Rf + (n + 1) · Bwr is the circumferential length 2π · {Rf + ( This is because it corresponds to (n + 1/2) · Bwr. Hereinafter, the integer value N is referred to as the pit number N.

Subsequently, in step S106, the controller 90 calculates the circumferential pit interval Bwt (n) by the following equation.
Bwt (n) = 2π · {Rf + (n + ½) · Bwr} / N
This calculation is to obtain a circumferential pit interval Bwt (n) obtained by dividing the moving distance of the laser spot during one rotation of the table 21 by the number of pits N. That is, the circumferential pit interval Bwt (n) obtained by correcting the circumferential pit interval Bwt input by the operator is calculated. As a result, when the distance of movement of the laser spot during one rotation of the table 21 is divided by the pit interval Bwt (n), there is no remainder (so small that it can be ignored). The phase of the signal waveform is the same. Hereinafter, this circumferential pit interval Bwt (n) is referred to as a corrected circumferential pit interval Bwt (n).

  Subsequently, in step S108, the controller 90 determines whether or not the difference between the circumferential pit interval Bwt input and set by the operator and the corrected circumferential pit interval Bwt (n) calculated in step S106 is within an allowable limit. Determine whether. Here, the value obtained by dividing the absolute value | Bwt−Bwt (n) | of the difference between the circumferential pit interval Bwt and the corrected circumferential pit interval Bwt (n) by the circumferential pit interval Bwt is an allowable value D. Or less.

  Immediately after the number of pits N is set, the difference between the circumferential pit interval Bwt and the corrected circumferential pit interval Bwt (n) is within the allowable limit, so the determination in step S108 is “Yes”, and the controller 90 advances the process to step S110. In step S110, the controller 90 calculates the pulse signal period T (n) by dividing the corrected circumferential pit interval Bwt (n) by the linear velocity F. Subsequently, in Step S112, the controller 90 outputs the pulse signal cycle T (n) and the duty ratio Dy set by the operator to the pulse signal supply device 50. Accordingly, the pulse signal supply device 50 creates pulse signal information representing the pulse signal P (n) based on the pulse signal cycle T (n) and the duty ratio Dy, and stores the pulse signal information in the memory 50a.

Subsequently, the controller 90 increments the variable n by the value “1” in step S114, and in the subsequent step S116, confirms that the radius position (Rf + n · Bwr) does not exceed the end radius position Re. The process returns to step S106. Accordingly, in this case, the circumferential length of the second circumference starting from the outer position by the radial pit interval Bwr from the initial radial position Rf (the distance of the second circumference in which the laser spot moves in a spiral shape ) is the number of pits N The divided value is calculated as a corrected circumferential pit interval Bwt (n). The corrected circumferential pit interval Bwt (n) is calculated so that the number of pits N is the same in the first and second laps, and the phase of the pulse signal waveform is the same at the position where the table 21 has just made one rotation. Therefore, the first and second pits are aligned on the line starting from the rotation center of the table 21.

  By repeating such processing, if the difference between the circumferential pit interval Bwt and the corrected circumferential pit interval Bwt (n) is within the allowable limit, the corrected circumferential pit interval Bwt (n) for the same number of pits N is calculated. The corresponding pulse signal period T (n) and duty ratio Dy (constant) are sequentially output to the pulse signal supply device 50. As the value of the variable n increases, the radial position of the laser spot increases and the corrected circumferential pit interval Bwt (n) also increases. As a result, the difference between the circumferential pit interval Bwt and the corrected circumferential pit interval Bwt (n) gradually increases. If it is determined in step S108 that the difference between the circumferential pit interval Bwt and the corrected circumferential pit interval Bwt (n) exceeds the allowable limit, the controller 90 advances the process to step S104. Therefore, a new pit number N corresponding to the radial position is calculated. In step S106, a corrected circumferential pit interval Bwt (n) corresponding to the new pit number N is calculated.

  At the radial position where the number of pits N has been changed, the pits are not aligned on the line starting from the rotation center of the table 21, but since the entire workpiece OB is only a part, the influence is almost not. Absent. Further, by changing the number of pits according to the radial position, the change in the circumferential pit interval at the radial position can be made minute.

  When such a process is repeated and the radius position (Rf + n · Bwr) exceeds the end radius position Re in step S116, the controller 90 ends the pulse signal generation routine in step S118. The controller 90 outputs a pulse signal cycle T (n) and a duty ratio Dy for each radial position to the pulse signal supply device 50 by executing this pulse signal generation routine. Then, the pulse signal supply device 50 creates pulse signal information for each radial position, and stores the created pulse signal information in the memory 50a.

  In the present embodiment, since the index signal is output from the encoder 22a only once during one rotation of the table 21, the time from when the reference rotation position is detected until the next reference rotation position is detected. The interval between the laser beam irradiation position movements is the circumference of one round of the laser beam irradiation locus. Therefore, in the pulse signal creation routine, for each irradiation position movement section, the corrected circumferential pit interval is set so that no remainder is generated when the circumferential length, which is the movement distance of the irradiation position, is divided by the circumferential pit interval Bwt. Bwt (n) is calculated. In this case, the variable n represents the number of rounds from the position where n = 0 as the radial position in the innermost circumference. Thereby, pits can be arranged on a line starting from the rotation center of the table 21.

FIG. 5 is a table showing actual numerical values calculated by executing the pulse signal generation routine. From the left line, the variable n, the radial position (mm), the movement distance (mm) of the irradiation position movement section (one turn), the number of pits N (pieces), and the corrected circumferential pit interval Bwt (n) (nm) To express. In this example,
Initial radius position Rf = 30mm
Circumferential pit spacing Bwt = 400 nm
Radial pit spacing Bwr = 400nm
It is said.
In this case, the circumferential pit interval Bwt and the radial pit interval Bwr are made equal in order to evenly arrange the pits at the positions of the apexes of the square (intersection of the graph paper).

  In the example shown in FIG. 5, the allowable limit of the difference between the circumferential pit interval Bwt and the corrected circumferential pit interval Bwt (n) is set to 0.1% (0.4 nm). Therefore, when the variable n changes from n = 74 to n = 75, when n = 150 changes to n = 151, when n = 226 changes to n = 227, the number of pits N is changed. At the radial position where the number of pits N is changed, the pits are not aligned on the line starting from the rotation center of the table 21, but as can be seen from this example, it is only a part of the whole, so There is no problem in creating the substrate.

  Next, laser processing will be described. The operator sets the workpiece OB on the table 21 and uses the input device 91 to instruct the controller 90 to start the laser machining start routine. FIG. 3 is a flowchart showing a laser processing control routine. The laser processing control routine is stored as a control program in the ROM of the controller 90, and is started in step S200.

  When the laser processing control routine is started, the controller 90 first outputs a rotation start command to the spindle motor control circuit 53 in step S202. The controller 90 inputs a signal representing the radial position detected by the radial position detection circuit 52 when outputting the rotation command, and the spindle motor is such that the linear velocity at the radial position of the laser spot becomes the designated linear velocity F. 22 is calculated, and the calculated rotation speed is output to the spindle motor control circuit 53. The spindle motor control circuit 53 calculates the rotation speed of the spindle motor 22 using the rotation detection pulse train signal (A-phase signal, B-phase signal) from the encoder 22a, and the calculated rotation speed is the rotation input from the controller 90. The rotation control of the spindle motor 22 is started so as to be equal to the speed. After outputting the rotation start instruction, the controller 90 repeats the calculation of the rotation speed of the spindle motor 22 according to the radial position by an interrupt routine different from this routine, and the calculated rotation speed is converted to the spindle each time. Output to the motor control circuit 53.

  Subsequently, the controller 90 outputs a movement command to the initial radius position to the feed motor control circuit 54 in step S204. The initial radius position is an initial radius position Rf input in advance by the operator. The feed motor control circuit 54 controls the rotation of the feed motor 23 until the irradiation position of the laser beam coincides with the initial radial position Rf while inputting the radial position detected by the radial position detection circuit 52 according to this movement command. The table 21 is moved. When the radial position detected by the radial position detection circuit 52 becomes equal to the initial radial position Rf, the feed motor control circuit 54 stops the rotation of the feed motor 23.

  When the controller 90 outputs a movement command in step S204, in step S206, the controller 90 inputs the radius position from the radius position detection circuit 52 and waits until the radius position becomes the initial radius position Rf. When it is confirmed that the table 21 has moved to the initial radius position Rf (S206: Yes), a drive start command is output to the laser drive circuit 70 and a DC signal is output to the pulse signal supply device 50 in step S208. The start command is output. As a result, the laser drive circuit 70 outputs a continuous laser drive signal set to the non-processing intensity to the laser light source 31. The laser light source 31 is driven by the drive signal output from the laser drive circuit 70 and emits non-processing laser light. As a result, a light spot of non-machining laser light is formed on the surface of the workpiece OB, and the reflected light of this light spot is detected by the photodetector 38. In this case, the processing object OB is not processed by the irradiation of the non-processing laser beam.

  Subsequently, in step S210, the controller 90 outputs a focus servo start command to the focus servo circuit 63, a circuit that drives the focus actuator 39 (not shown), and the S-shaped detection circuit. Thereby, the focus position of the laser beam moves in the optical axis direction of the laser beam, and the focus servo is started at the timing when the focus position of the laser beam coincides with the surface of the workpiece OB. Then, the objective lens 35 is driven and controlled in the optical axis direction of the laser light so that the focal position of the laser light coincides with the surface of the workpiece OB.

  Subsequently, in step S212, the controller 90 reads a rotation signal indicating the rotation of the spindle motor 22 from the encoder 22a, and waits until an index signal is input. This index signal is a signal output from the encoder 22a every time the rotation position of the table 21 reaches the reference rotation position, that is, a signal output at the reference rotation position only once while the table 21 rotates once.

  When the controller 90 detects that the index signal is input in step S212, the controller 90 outputs a pulse signal output start command to the pulse signal supply device 50 in step S214, and in step S216, the controller 90 outputs to the feed motor control circuit 54. In response, a command to start moving in the radial direction is output. When receiving the pulse signal output start command output from the controller 90, the pulse signal supply device 50 outputs the pulse signal P (n) to the laser driving circuit 70 in accordance with the pulse signal information stored in the memory 50a. As a result, laser light having a processing intensity is intermittently emitted from the laser light source 31. At the same time, the feed motor 23 is driven by the feed motor control circuit 54 and the table 21 also moves in the radial direction.

  When the controller 90 outputs a movement command in the radial direction, the controller 90 inputs a signal indicating the radial position detected by the radial position detection circuit 52, and the table 21 rotates once based on the radial position and the linear velocity F. Then, the moving speed at which the moving distance in the radial direction of the table 21 becomes the radial pit interval Bwr is calculated, and the rotation speed corresponding to the calculated moving speed is output to the feed motor control circuit 54. The feed motor control circuit 54 calculates the rotation speed of the feed motor 23 using the rotation detection pulse train signal output from the encoder 23a, and feeds the calculated rotation speed to be equal to the rotation speed input from the controller 90. The rotation control of the motor 23 is started. The controller 90 repeats the calculation of the rotation speed of the feed motor 23 by an interrupt routine different from this routine after outputting the radial movement instruction in step S216, and each time the calculated rotation speed is calculated. Output to the feed motor control circuit 54.

  Here, the processing of the pulse signal supply device 50 started in step S214 will be described with reference to FIG. FIG. 4 is a flowchart showing a pulse signal output control routine executed by the pulse signal supply device 50. The pulse signal supply device 50 includes, for example, a microcomputer as a main part, and stores a pulse signal output control routine in the ROM as a control program.

  When the pulse signal output device 50 receives a pulse signal output start command from the controller 90, the pulse signal supply device 50 starts a pulse signal output control routine in step S300. First, in step S302, the pulse signal supply device 50 sets the value of the variable n to “0”. Subsequently, in step S <b> 304, the pulse signal P (n) is output to the laser driving circuit 70. The pulse signal P (n) is output based on the pulse signal information stored in the memory 50a by the above-described pulse signal creation routine. Accordingly, the controller 90 outputs a pulse signal (pulse train signal) from which the designated pulse signal cycle T (n) and the duty ratio Dy are obtained. As a result, laser light having a processing intensity is intermittently emitted from the laser light source 31 in synchronization with the pulse signal P (n).

  Subsequently, in step S306, the pulse signal supply device 50 increments the variable n by the value “1”, and in the subsequent step S308, determines whether or not the index signal is input from the encoder 22a. While the index signal is not input, it is determined in step S310 whether or not a stop command is input from the controller 90. If no stop command is input, the process returns to step S308. During this time, the pulse signal supply device 50 continues to output the pulse signal to the laser drive circuit 70. When an index signal is input from the encoder 22a (S308: Yes), the process returns to step S304. Accordingly, the pulse signal supply device 50 switches to the pulse signal period T (n) corresponding to the outer circumference of the one and outputs the pulse signal to the laser driving circuit 70.

  Thus, each time the table 21 rotates once and the index signal is input, the pulse signal supply device 50 switches the pulse signal output to the laser driving circuit 70 to a new cycle. Thereby, as shown in FIG.7 (b), the pit P is formed in the arrangement | positioning used as the vertex position of a square on the surface of the workpiece OB.

  Returning to the explanation of the laser processing control routine of FIG. When the laser processing is started in steps S214 and S216, the controller 90 subsequently determines in step S218 whether or not the radial position detected by the radial position detection circuit 52 is equal to or greater than the end radial position Re. The end radius position Re is a value input and set in advance by the operator as a laser processing condition. The process of step S218 is repeated until the radius position becomes equal to or greater than the end radius position Re. Accordingly, during this period, a pulse signal is output from the pulse signal supply device 50, and laser processing of the workpiece OB is continued.

  When the laser processing advances and the radius position detected by the radius position detection circuit 52 becomes equal to or greater than the end radius position Re (S218: Yes), the controller 90 outputs an operation stop command to the focus servo circuit 63 in step S220. Thus, the focus servo control by the focus servo circuit 63 is stopped. Subsequently, the controller 90 outputs a laser beam irradiation stop command to the laser driving circuit 70 in step S222. At the same time, a pulse signal output stop command is output to the pulse signal supply device 50.

  When the pulse signal supply device 50 receives a pulse signal output stop command, the determination in step S310 in the pulse signal output control routine of FIG. 4 is “Yes”, and in step S312, the output of the pulse signal P (n) is stopped. In step S314, the pulse signal output control routine is terminated.

  When the output of the pulse signal is stopped in this way, the controller 90 outputs a radial movement stop command to the feed motor control circuit 54 in step S224. As a result, the feed motor control circuit 54 stops the feed motor 23. Subsequently, the controller 90 outputs a rotation stop command to the spindle motor control circuit 53 in step S226. As a result, the spindle motor control circuit 53 stops the rotation of the spindle motor 22. And the controller 90 complete | finishes a laser processing control routine in step S228.

  Here, the pulse signal output from the pulse signal supply device 50 will be supplementarily described. The pulse signal supply device 50 switches the pulse signal at the timing at which the index signal is input. As shown in FIG. 6A, this pulse signal has a low level width in the pulse signal from the time when the index signal is input. It is set to become a high level after a time of about 1/2 of WL (time) has elapsed. Hereinafter, this reason will be described.

  In calculation, the pulse signal before the index signal is input and the pulse signal after the index signal is input should have the same phase at the timing when the index signal is input. However, the phase shifts to some extent due to rotational jitter. For this reason, if a signal starting from a high level is output at the timing when the index signal is input, and the phase of the pulse signal before the index signal is input is advanced, the state of the high level is also maintained immediately before the index signal is input. Become. Therefore, the high level state continues before and after the timing when the index signal is input, and the shape of the pit P is destroyed as shown in FIG.

  Therefore, in this embodiment, 1 / of the low level width WL (time) from the time when the index signal is input so that the shape of the pit does not collapse even if such a phase shift due to rotational jitter occurs. A pulse signal that becomes high level after about 2 hours has elapsed is output. In setting this time, if it is shorter than the low level time, it can be appropriately changed after confirming the range of phase shift.

  According to the laser processing apparatus 1 of the present embodiment described above, the number of pits for one round is the same as the number of pits for one round at one inner radial position, and the laser spot at each radial position is A circumferential pit interval is calculated for each radial position so that a remainder is not generated when the movement distance is divided by the circumferential pit interval. The calculated circumferential pit interval Bwt (n), that is, the corrected circumferential pit interval Bwt. Based on (n), the pulse signal period T (n) is determined. Then, the pulse signal information specified by the pulse signal period T (n) and the duty ratio Dy is stored in the memory 50a, and the pulse signal of the pulse signal period T (n) corresponding to the radial position at the time of laser processing is stored. Output to the laser drive circuit 70.

  Further, since the phase of the pulse signal is set so as to become high level at a timing when about half of the low-level width WL has elapsed from the time when the index signal is input to the pulse signal supply device 50, The effect of rotational jitter does not appear in the pit shape. As a result, as shown in FIG. 7B, the pits P can be formed on the surface of the workpiece OB in an arrangement where the apexes of the square are located. Therefore, if the laser-processed workpiece OB is used as an LED substrate, the light extraction efficiency can be improved.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the object of the present invention.

  For example, in this embodiment, pulse signal information for each rotation of the table 21 is stored in advance in the memory 50a of the pulse signal supply device 50, and the pulse signal is switched each time an index signal is input during laser processing. However, the pulse signal information for each (1 / m) rotation may be stored in the memory 50a, and the pulse signal output from the pulse signal supply device 50 may be switched each time the table 21 rotates (1 / m). . Note that m is an integer of 2 or more. In this case, a rotational position detection circuit 80 may be provided as indicated by a broken line in FIG. The rotational position detection circuit 80 counts the number of pulses of the rotation detection pulse train signal output from the encoder 22a provided in the spindle motor 22, and the count value is a set value (A, 2A, 3A ..., (m-1) A). The reference rotational position detection signal is output to the pulse signal supply device 50 each time. The count value is reset each time an index signal is input. The set value A is the number of pulses of a rotation detection pulse train signal output from the encoder 12a when the table 21 rotates (1 / m).

  As a result, the pulse signal supply device 50 receives the reference rotation position detection signal including the index signal every time the table 21 reaches the set reference rotation position, and outputs it to the laser drive circuit 70 each time the signal is input. Switch the pulse signal to be used.

In this case, the calculation of the number of pits N in step S104 in the pulse signal creation routine of FIG.
N = INT [2π · {Rf + ((2n + 1) / 2m) · Bwr} / (Bwt · m)]
And the calculation of the circumferential pit interval Bwt (n) in step S105 is
Bwt (n) = 2π · {Rf + ((2n + 1) / 2m) · Bwr} / N · m
And it is sufficient.

  Thus, if the pulse signal is switched every time the table 21 rotates (1 / m), it becomes difficult to be influenced by the rotational jitter, and a pit having a good shape can be formed. In the above-described example, the reference rotation position for setting the timing for switching the pulse signal is set to an angular position obtained by equally dividing one rotation (360 °) of the table 21. However, it is not always necessary to set the reference rotation position equally. If the circumferential pit interval Bwt (n) is obtained by calculation according to the movement distance between the reference rotation positions, any angular position can be set.

  In addition, the pits may be arranged in a staggered pattern as shown in FIG. 8 as well as the square apex position as shown in FIG. 7B. That is, the formation position of the pits P may be provided on a straight line L connecting the center position C between the adjacent pits P and the rotation center O on the inner circumference (the locus along which the laser spot moves). In this case, the radial pit interval Bwr is a distance between adjacent circumferential trajectories.

  In such a staggered uniform arrangement, the pits can be formed most densely by setting the circumferential pit interval Bwt to a value obtained by multiplying the radial pit interval Bwr by (√3) / 2. Light extraction efficiency can be increased.

  In order to form the pits in a zigzag uniform arrangement, as shown in FIG. 9, the output timing of the pulse signal every other round is delayed by a half of the pulse signal period T (n). do it. FIG. 10 shows a pulse signal output control routine when pits are formed in a staggered uniform arrangement. This pulse signal output control routine is obtained by adding the processes of steps S309 and S311 to the pulse signal output control routine (FIG. 4) of this embodiment.

  When the pulse signal supply device 50 receives the index signal in step S308, it determines whether or not the variable n is an odd number in step S309. If the variable n is an odd number, in step S311, after waiting for a time ½ of the pulse signal period T (n), the process proceeds to step S304 to output the pulse signal P (n). On the other hand, if the variable is an even number, the process of step S311 is skipped, the process proceeds to step S304 as it is, and the pulse signal P (n) is output. Accordingly, the timing at which the pulse signal is output every other round is shifted by a time that is ½ of the pulse signal period T (n), so that the pits can be formed in a staggered pattern as shown in FIG.

  In this case, when calculating the circumferential pit interval Bwt (n) (S104, S106) in the pulse signal generation routine of FIG. 2, the moving distance [2π · {Rf + (n + 1/2) · Bwr for one round at the radial position]. }] Plus a value [2π · {Rf + (n + ½) · Bwr} + Bwt / 2] obtained by adding 1/2 of the circumferential pit interval Bwt input and set by the operator for one round at the radial position What is necessary is just to calculate as a distance.

  In the present embodiment or the modification, the controller 90 is instructed to start a pulse signal creation routine, and after the pulse signal information is stored in the pulse signal supply device 50, laser processing is started. When the start of the laser processing control routine is instructed to the controller 90, a pulse signal generation routine may be started separately from this routine. Even in such a case, since a predetermined time is required until the laser processing is started after the start of the laser processing control routine is instructed, the memory 50a of the pulse signal supply device 50 is necessary for laser processing within this time. The pulse signal information is sufficiently stored.

  Further, if the time taken to create the pulse signal information is shorter than the time during which the laser beam moves through the irradiation position moving section, the pulse signal supply device 50 stores the pulse signal information in one section of the irradiation position moving section and then the laser. Processing may be started, and pulse signal information in the next irradiation position movement section may be generated and stored in the pulse signal supply device 50 while the laser beam moves in the irradiation position movement section. According to this, since the capacity of the memory 50a of the pulse signal supply device 50 can be reduced, the cost of the device can be suppressed.

  In this embodiment or the modification, the rotation signal (index signal, rotation detection pulse train signal) output from the encoder 22a is used for detecting the reference rotation position. However, any configuration that can detect the set rotation position is possible. For example, it is not limited to this. For example, a configuration may be adopted in which a mark is provided on the side surface of the table 21 and a sensor facing the side surface of the table 21 is provided so that a detection signal of the reference rotation position is output every time the sensor detects the mark.

  In the present embodiment, the table 21 is moved when the irradiation position of the laser beam is moved in the radial direction of the table 21, but the processing head 30 is moved in the radial direction of the table 21. May be. Further, both the table 21 and the processing head 30 can be moved in association with each other.

  Furthermore, in this embodiment, at the time of laser processing, the irradiation position of the laser beam is moved from the side closer to the rotation center of the table 21 to the side farther, that is, in the direction in which the radius increases. You may make it move from the far side to the near side from the center of rotation, that is, in a direction in which the radius decreases. In the present embodiment, the radial pit interval Bwr is the same as the circumferential pit interval Bwt, but it is not necessarily required to be the same.

  The spindle motor 22 in the present embodiment corresponds to the rotating means of the present invention, the feed motor 23 in the present embodiment corresponds to the radial direction irradiation position moving means of the present invention, and the laser drive circuit 70 in the present embodiment is the main drive circuit. The encoder 23a and the radial position detection circuit 52 in the present embodiment correspond to the radial position detection means of the present invention, and the encoder 22a in the present embodiment corresponds to the rotation signal output means of the present invention. The spindle motor control circuit 53 and the controller 90 in this embodiment correspond to the rotational speed control means of the present invention. Further, the encoder 22a in the present embodiment corresponds to the reference rotational position detecting means of the present invention, the input device 91 and the controller 90 in the present embodiment correspond to the circumferential interval setting means of the present invention, and the pulse signal generation in the present embodiment. The functional unit of the controller 90 that performs steps S102 to S108 of the routine corresponds to the circumferential interval correction unit of the present invention. Further, the functional unit of the controller 90 that performs step S110 of the pulse signal generation routine in the present embodiment corresponds to the pulse period calculation means of the present invention, and the functional unit of the controller 90 that performs step S112 of the pulse signal generation routine in the present embodiment. The pulse signal supply device 50 including the memory 50a corresponds to the pulse signal information storage means of the present invention. The pulse signal supply device 50 in this embodiment corresponds to the laser drive control means of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Laser processing apparatus, 21 ... Table, 22 ... Spindle motor, 22a ... Encoder, 23 ... Feed motor, 23a ... Encoder, 30 ... Processing head, 31 ... Laser light source, 38 ... Photo detector, 39 ... Focus actuator, 50 ... Pulse Signal supply device 50a ... Memory 52 ... Radial position detection circuit 53 ... Spindle motor control circuit 54 ... Feed motor control circuit 70 ... Laser drive circuit 80 ... Rotation position detection circuit 90 ... Controller 91 ... Input device 92. Display device.

Claims (10)

A table for setting a flat workpiece,
Rotating means for rotating the table;
A machining head having a laser light source for irradiating a workpiece to be rotated set and set on the table;
Radial irradiation position moving means for moving the irradiation position of the laser beam on the workpiece in the radial direction of the table by changing the relative position between the processing head and the table;
Laser driving means for intermittently emitting laser light from the laser light source by outputting a laser driving pulse signal to the laser light source, and forming processing marks at predetermined intervals on the surface of the processing object;
A radial position detecting means for detecting a radial position representing a distance from the rotation center of the table to the irradiation position of the laser beam;
Rotation signal output means for outputting a rotation detection signal each time the table rotates by a predetermined angle;
Based on the radial position detected by the radial position detection means and the rotation detection signal output by the rotation signal output means, the rotation is performed so that the linear velocity at the irradiation position of the laser light becomes a constant set speed. A laser processing apparatus comprising: a rotational speed control means for controlling the rotational speed of the means;
A reference rotation position detecting means for detecting the reference rotation position every time the table rotates and reaches a preset reference rotation position;
A circumferential interval setting means for setting a circumferential interval between machining traces formed on the workpiece;
The number of processing traces formed when the table rotates once is made the same in the inner circumference and the outer circumference adjacent to each other in the laser beam irradiation trajectory, and from the reference rotation position to the next For each laser beam irradiation position movement section until the reference rotation position is detected, it is set by the circumferential interval setting means based on the movement distance of the laser light irradiation position in the irradiation position movement section. A circumferential interval correction means for calculating a corrected circumferential interval in which the circumferential interval of the processed trace is corrected;
Pulse period calculation means for calculating the period of the pulse signal for laser driving based on the corrected circumferential interval calculated by the circumferential interval correction means and the constant linear velocity for each irradiation position movement section of the laser light When,
Pulse signal information storage means for storing pulse signal information for outputting a laser drive pulse signal of the calculated period;
Laser drive control means for outputting a laser drive pulse signal from the laser drive means at a cycle according to the irradiation position movement section of the laser light according to the pulse signal information stored in the pulse signal information storage means at the time of laser processing; A laser processing apparatus comprising:   When the difference between the circumferential interval of the machining trace set by the circumferential interval setting unit and the corrected circumferential interval after correcting the circumferential interval exceeds an allowable value, the circumferential interval correction unit 2. The laser processing apparatus according to claim 1, wherein the number of the processing traces formed when the table rotates once is changed so that the difference falls within an allowable value.   The circumferential interval correction means, for each irradiation position movement section of the laser beam, the movement distance of the irradiation position of the laser beam in the irradiation position movement section in the circumferential direction of the machining trace set by the circumferential interval setting means The corrected circumferential interval is calculated by correcting the circumferential interval of the machining trace set by the circumferential interval setting means so that a remainder does not occur when dividing by the interval. Laser processing equipment.   The laser drive control means is configured to change the laser drive level from a low level to a high level after a set time shorter than a low level time width of the laser drive pulse signal has elapsed since the reference rotational position was detected. 4. The laser processing apparatus according to claim 1, wherein the laser driving means is controlled to output a pulse signal for use.   5. The laser processing apparatus according to claim 1, wherein the reference rotation position detection unit detects a plurality of reference rotation positions set in one rotation of the table. 6. The reference rotation position detecting means detects a reference rotation position once in one rotation of the table,
The circumferential interval correction means is set to a distance obtained by adding a distance of half the circumferential interval of the set processing trace to the moving distance of the irradiation position of the laser beam in the irradiation position moving section. Calculating a corrected circumferential interval that corrects the set circumferential interval of the machining trace so that no remainder is generated when dividing by the circumferential interval of the machining trace,
The laser drive control means sets the timing at which the output of the laser drive pulse signal is started every other time when the reference rotational position is detected to a half of the calculated period of the pulse signal. 3. The laser processing apparatus according to claim 1, wherein the laser driving means is controlled so as to be shifted by a distance. A table for setting a flat workpiece,
Rotating means for rotating the table;
A machining head having a laser light source for irradiating a workpiece to be rotated set and set on the table;
Radial irradiation position moving means for moving the irradiation position of the laser beam on the workpiece in the radial direction of the table by changing the relative position between the processing head and the table;
Laser driving means for intermittently emitting laser light from the laser light source by outputting a laser driving pulse signal to the laser light source, and forming processing marks at predetermined intervals on the surface of the processing object;
A radial position detecting means for detecting a radial position representing a distance from the rotation center of the table to the irradiation position of the laser beam;
Rotation signal output means for outputting a rotation detection signal each time the table rotates by a predetermined angle;
Based on the radial position detected by the radial position detection means and the rotation detection signal output by the rotation signal output means, the rotation is performed so that the linear velocity at the irradiation position of the laser light becomes a constant set speed. Rotational speed control means for controlling the rotational speed of the means;
A method for outputting a pulse signal for laser drive in a laser processing apparatus, comprising: a reference rotation position detection unit that detects the reference rotation position every time the table rotates and reaches a preset reference rotation position;
A circumferential interval setting step for setting a circumferential interval between machining traces formed on the workpiece;
The number of processing traces formed when the table rotates once is made the same in the inner circumference and the outer circumference adjacent to each other in the laser beam irradiation trajectory, and from the reference rotation position to the next For each laser beam irradiation position movement interval until the reference rotation position is detected, the circumferential interval setting step is set based on the movement distance of the laser beam irradiation position in the irradiation position movement interval. A circumferential interval correction step for calculating a corrected circumferential interval in which the circumferential interval of the processed trace is corrected;
A pulse period calculating step for calculating a period of the laser driving pulse signal based on the corrected circumferential interval calculated by the circumferential interval correcting step and the constant linear velocity for each irradiation position movement section of the laser light. When,
A pulse signal information storage step for storing pulse signal information for outputting a laser drive pulse signal of the calculated period;
A laser drive control step of outputting a laser drive pulse signal from the laser drive means at a cycle according to the laser beam irradiation position movement section in accordance with the pulse signal information stored in the pulse signal information storage step. A method of outputting a pulse signal for driving a laser in a laser processing apparatus.   In the circumferential interval correction step, when the difference between the circumferential interval of the machining trace set in the circumferential interval setting step and the corrected circumferential interval in which the circumferential interval is corrected exceeds an allowable value, 8. The pulse signal for laser driving in a laser processing apparatus according to claim 7, wherein the number of the processing traces formed when the table rotates once is changed so that the difference falls within an allowable value. Output method.   The circumferential interval correction step includes, for each irradiation position movement section of the laser beam, a movement distance of the irradiation position of the laser beam in the irradiation position movement section in a circumferential direction of the machining trace set by the circumferential interval setting step. 9. The corrected circumferential interval obtained by correcting the circumferential interval of the machining trace set by the circumferential interval setting means is calculated so that a remainder does not occur when dividing by the interval. Of a pulse signal for laser drive in the laser processing apparatus. The reference rotation position detecting means detects a reference rotation position once in one rotation of the table,
In the circumferential interval correction step, the distance obtained by adding a half distance of the circumferential interval of the set processing trace to the movement distance of the irradiation position of the laser beam in the irradiation position movement section is set. Calculating a corrected circumferential interval that corrects the set circumferential interval of the machining trace so that no remainder is generated when dividing by the circumferential interval of the machining trace,
In the laser drive control step, when the reference rotation position is detected, the timing for starting the output of the laser drive pulse signal every other time is set to 1/2 of the calculated period of the pulse signal. 9. The laser driving pulse signal output method in a laser processing apparatus according to claim 7, wherein the laser driving means is controlled so as to be shifted by a distance.

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