JP2001330966A - Laser plotter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser plotter capable of highly accurately performing the correcting processing of the uneven density of plotting pattern. SOLUTION: In the laser plotter for plotting pattern by modulating a laser beam by a plotting signal formed based on raster data, deflecting the modulated laser beam in a main scanning direction by a polygon mirror 67, and then, irradiating a substrate on a plotting stage 5 with the laser beam, and also moving the plotting stage 5 in a sub scanning direction, the laser plotter is provided with a light quantity correction circuit 123 for adjusting the light quantity of the laser beam at a correction position on one scanning line in accordance with light quantity correction data (c).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser drawing apparatus for drawing a desired pattern by irradiating a processing object such as a printed circuit board with a laser beam, and more particularly to a density unevenness and a positional deviation of a drawn pattern. The present invention relates to a technique for correcting a high accuracy.

[0002]

2. Description of the Related Art A conventional laser drawing apparatus includes a table on which a printed wiring board on which a photosensitive material is adhered, a polygon mirror for deflecting a drawing laser beam in a main scanning direction, an fθ lens, and the like. An image optical system and a moving mechanism for moving the table in the sub-scanning direction are provided. This apparatus modulates a laser beam based on raster data read by a drawing clock, deflects the modulated laser beam in the main scanning direction to irradiate a printed wiring board on a table, and simultaneously modulates the laser beam in the sub-scanning direction. By moving the table, a desired pattern is drawn on the printed wiring board. The fθ lens is used to make the spot of the laser beam linearly move on the printed wiring board at a constant speed in the main scanning direction.

[0003] By the way, as a demand for the fθ lens, it is necessary to increase the image recording density by reducing the image forming spot diameter over the entire effective area where image recording can be performed, and to increase the scanning angle to make the effective area wider. There is a request to do. If the fθ lens is designed with priority given to such a requirement, on the other hand, there is a problem that the fθ characteristic (linear constant velocity characteristic) is somewhat sacrificed. Due to this problem, even if the polygon mirror rotates stably at a constant angular speed, the main scanning speed of the beam spot on the printed wiring board is not constant, and the density of the drawing pattern is uneven in the main scanning direction. Will be lost.

In order to correct such unevenness in the density of the drawing pattern in the main scanning direction caused by the non-constant main scanning speed of the beam spot, for example, Japanese Patent Application Laid-Open Nos. 4-41616 and 4-41617. There is a laser drawing apparatus as shown in Japanese Patent Application Laid-Open Publication No. H11-209,873. These apparatuses adjust the frequency of the drawing clock applied to the modulating means for modulating the laser beam based on the raster data read by the drawing clock in accordance with the change in the main scanning speed of the beam spot caused by the characteristics of the fθ lens. It has frequency control means for controlling. In the device configured as described above, the frequency of the drawing clock applied to the modulating means is controlled in accordance with the change in the main scanning speed of the beam spot caused by the characteristics of the fθ lens. The main scanning pitch of the beam spot can be kept constant, and the density unevenness of the drawing pattern in the main scanning direction can be eliminated even if an fθ lens is used which is somewhat sacrificed.

Here, a description will be given of a conventional apparatus for the purpose different from that for eliminating the unevenness of density of a drawing pattern in the main scanning direction. This apparatus eliminates uneven density of a drawing pattern for each polygon surface caused by a variation in the reflectance of each reflecting mirror (polygon surface) of the polygon mirror.

For example, in an apparatus disclosed in Japanese Patent Application Laid-Open No. 10-186259, the light amount of a laser beam from each reflecting mirror of a polygon mirror is detected in advance by a start sensor, and the light amount of the laser beam detected by the start sensor is detected. Is controlled so as to be constant independently of the polygon surface to correct the light amount variation for each polygon surface, thereby eliminating the density unevenness of the drawing pattern for each polygon surface.

[0007]

However, the prior art having such a structure has the following problems. In the conventional apparatus described in JP-A-4-141616 and JP-A-4-141617 described above, it is not possible to correct the density unevenness of the drawing pattern in the main scanning direction caused by the non-constant main scanning speed of the beam spot. However, there is a problem that it is not possible to correct the density unevenness of the drawing pattern caused by the uneven light amount of the laser beam in one scan of the scanning optical system. Specifically, the unevenness in the light amount of the laser beam in one scan of the scanning optical system is caused by the variation in power efficiency of the laser beam in one scan of the scanning optical system. For example, even when the output of the laser light source is constant and the main scanning speed of the beam spot is controlled to be constant, factors in the optical path from the laser light source to the printed wiring board (for example, the laser beam irradiation range of the polygon surface) , Etc.), the power efficiency of the laser beam in one scan varies. For this reason, the laser beam intensity varies within one scan, and density unevenness occurs in the drawn pattern.

In the conventional apparatus disclosed in Japanese Patent Application Laid-Open No. H10-186259, unevenness in density of a drawing pattern for each polygon surface caused by variation in the reflectance of each reflecting mirror (polygon surface) of the polygon mirror is eliminated. However, as described above, it is not possible to correct the density unevenness of the drawing pattern caused by the unevenness in the light amount of the laser beam in one scan of the scanning optical system.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to provide a laser writing apparatus capable of performing a process of correcting uneven density of a writing pattern with high accuracy.

[0010]

The present invention has the following configuration in order to achieve the above object. That is, the laser drawing apparatus according to claim 1 modulates a laser beam with a drawing signal generated based on raster data, deflects the modulated laser beam in a main scanning direction by a deflecting unit, and places the laser beam on a mounting table. A laser drawing apparatus that draws a desired pattern on the processing target by irradiating the processing target with, and relatively moving the laser beam and the mounting table in the sub-scanning direction by a moving unit.
It is characterized in that it comprises a light amount adjusting means for adjusting the light amount at a correction position in one scanning line of the laser beam according to the light amount correction data.

According to a second aspect of the present invention, in the laser writing apparatus according to the first aspect, the light amount adjusting means adjusts a light amount correction value of a correction portion in one scanning line of the laser beam. It is characterized by comprising a memory unit for holding as correction data, and an adjusting unit for adjusting the light amount of the laser beam according to the light amount correction value from the memory unit.

According to a third aspect of the present invention, in the laser writing apparatus according to the first or second aspect, the light amount adjusting means is provided for each of a plurality of laser beams for simultaneous scanning and writing. It is characterized by the following.

According to a fourth aspect of the present invention, in the laser writing apparatus according to any one of the first to third aspects, the deflecting means is a scanning system including a polygon mirror. A light amount detecting means for detecting the light amount of the laser beam for each surface, and light amount correction data for each surface of the polygon mirror are calculated such that the light amount of the laser beam on each surface of the polygon mirror detected by the light amount detecting means is constant. Computing means for performing the operation.

According to a fifth aspect of the present invention, in the laser writing apparatus according to any one of the first to fourth aspects, the main scanning of the laser beam is started by receiving the laser beam. It is characterized by comprising a start sensor for detecting, and a start sensor light amount adjusting means for adjusting the light amount of the laser beam to the start sensor so that the amount of light received by the start sensor is constant.

[0015]

The operation of the first aspect of the present invention is as follows. The light amount adjusting means adjusts the light amount at a correction position in one scanning line of the laser beam according to the light amount correction data. Therefore, the unevenness in the amount of the laser beam in one scan of the scanning optical system is corrected, and the unevenness in the density of the drawing pattern is corrected with high accuracy.

According to the second aspect of the present invention, the memory section holds the light amount correction value of the correction portion in one scanning line of the laser beam as light amount correction data. The adjusting unit adjusts the light amount of the laser beam according to the light amount correction value from the memory unit. Therefore, it is possible to realize a configuration that highly accurately corrects density unevenness of a drawing pattern caused by unevenness in the amount of a laser beam in one scan of a scanning optical system.

According to the third aspect of the present invention, the light amount adjusting means is provided for each of a plurality of laser beams for simultaneous scanning and drawing. Therefore, in multi-beam writing using a plurality of laser beams, the light amount at the correction position of each laser beam is adjusted according to the corresponding light amount correction data, and the density unevenness of the writing pattern in one scan of each laser beam is highly accurate. Is corrected to Further, the light amount of each laser beam is adjusted so as to be constant according to the light amount correction data, and the unevenness in the density of the drawing pattern for each laser beam due to the variation in the light amount for each laser beam is corrected with high accuracy.

According to the fourth aspect of the present invention, the light amount detecting means detects the light amount of the laser beam for each surface of the polygon mirror. The calculating means calculates light amount correction data for each surface of the polygon mirror such that the light amount of the laser beam on each surface of the polygon mirror detected by the light amount detecting means is constant. Therefore, the light amount correction data for each surface of the polygon mirror is automatically calculated, and the light amount of the laser beam on each surface of the polygon mirror is adjusted according to the calculated light amount correction data for each surface of the polygon mirror. In addition, the variation in the amount of the laser beam for each surface of the polygon mirror due to the variation in the reflectance of each surface of the polygon mirror is corrected, and the uneven density of the drawing pattern for each surface of the polygon mirror is corrected.

According to the apparatus described in claim 5, the start sensor detects the start of the main scanning of the laser beam by receiving the laser beam. The start sensor light amount adjusting means adjusts the light amount of the laser beam to the start sensor so that the amount of light received by the start sensor is constant. Therefore, even when the light amount of the laser beam is changed in accordance with the type of the processing object, the amount of light received by the start sensor can be kept constant, and the scanning by the start sensor due to the fluctuation of the light amount of the laser beam can be started. Signal jitter (position shift) is prevented.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. A printed wiring board manufacturing apparatus, which is an example of a laser drawing apparatus according to the present invention, has first to fourth correction functions as described below. (1) The first correction function is a function of correcting unevenness in density of a drawing pattern caused by unevenness in the amount of a laser beam in one scan of a scanning optical system. (First Correction Example) (2) In addition to the above-described first correction function, the second correction function
This function corrects uneven density of a drawing pattern for each polygon surface caused by variation in the reflectance of each reflecting mirror (polygon surface) of the polygon mirror. (Second Correction Example) (3) The third correction function is a function of correcting unevenness in density of a drawing pattern for each laser beam caused by a variation in the amount of light for each laser beam. (Third Correction Example) (4) The fourth correction function is a function of correcting a position shift of a drawing pattern caused by a fluctuation in the amount of laser beam to the start sensor. (Fourth Correction Example) A printed wiring board manufacturing apparatus having such first to fourth correction functions is configured as follows.

FIG. 1 is a perspective view showing a schematic configuration of a printed wiring board manufacturing apparatus which is an example of a laser drawing apparatus according to the present invention.

As shown in FIG. 1, the printed wiring board manufacturing apparatus according to this embodiment is roughly divided into a drawing stage 5 on which a printed wiring board (object to be processed) S on which a photosensitive material is applied is mounted. An imaging optical system 21 including a polygon mirror 67 and an fθ lens 68 for deflecting the drawing laser beam LB in the main scanning direction (x direction);
A moving mechanism for moving in the sub-scanning direction (y direction);
It comprises a data processing unit 101 for processing artwork data of a printed wiring board designed using D (Computer Aided Design), and a drawing control unit 102 for performing drawing control based on the data from the data processing unit 101. ing.

The moving mechanism of the drawing stage 5 is configured as follows. A pair of guide rails 3 is provided on the upper surface of the base 1 of the apparatus, and a feed screw 9 rotated by a servomotor 7 is provided between the guide rails 3. The drawing stage 5 is screwed to the feed screw 9 at its lower part. Drawing stage 5
Has a stage base 10 slidably mounted along the guide rails 3 and a mounting table 15 on which the printed wiring board S is mounted by suction.

The moving mechanism including the guide rail 3, the servo motor 7, and the feed screw 9 corresponds to the moving means in the present invention.

In the y direction (sub-scanning direction) in which the drawing stage 5 is moved by the drive of the servo motor 7, the processing position P
An imaging optical system 2 that irradiates a drawing laser beam LB downward while deflecting it in the x direction (main scanning direction) in Y.
1 is provided. The imaging optical system 21 is disposed above the base 1 by a gate-shaped frame. When the servo motor 7 is driven, the drawing stage 5 is connected to the imaging optical system 2.
It is designed to advance and retreat for one.

Next, the image forming optical system 21 will be described.
The laser light source 41 is, for example, a solid-state laser having a wavelength of 532 μm using a semiconductor as an excitation light source. This laser light source 41
The laser beam LBa emitted from the laser beam LBa is changed in direction by approximately 90 ° by the corner mirror 43 and is incident on the beam expander 45. The laser beam LBa adjusted to a predetermined beam diameter by the beam expander 45 is split into, for example, eight laser beams LBb by the beam splitter 47 (not shown in FIG. 1). The eight divided laser beams LBb are respectively condensed by a condenser lens 49 and a corner mirror 51 to obtain an acousto-optic modulator (AOM).
The light enters the crystal in the acousto-optic modulator 53 at the same time as being incident parallel to the light 53, and a drawing control unit 102 described later
Are independently modulated based on the raster data by the control signal from the CPU.

The laser beam LBc modulated by the acousto-optic modulator 53 is reflected by a corner mirror 55 and enters a relay lens system 57. The laser beam LBc emitted from the relay lens system 57 is guided to the polygon mirror 67 via the cylindrical lens 59, the corner mirror 61, the spherical lens 63, and the corner mirror 65. Then, a linear spot long in the main scanning direction (x direction) is formed on each surface of the polygon mirror 67.

The linear laser beam LBc, which has been deflected and scanned in the horizontal plane by the rotation of the polygon mirror 67 corresponding to the deflecting means of the present invention, passes through the fθ lens 68 and then has a long folding mirror 69 in the main scanning direction. Is folded downward. After being corrected by the field lens 71 so that the angle of incidence on the exposure surface becomes substantially vertical, the light is irradiated toward the mounting table 15 through the cylindrical lens 73. Cylindrical lens 7
Numeral 3 is long in the main scanning direction and has power only in the sub-scanning direction.

The linear spot on the polygon mirror 67 is divided into an fθ lens 68, a field lens 71,
The laser beam LB (maximum 8) moves in the main scanning direction (x direction) by rotating the polygon mirror 67 by forming a spot having a predetermined diameter on the mounting table 15 by the action with the cylindrical lens 73. Consisting of two laser beams).

The mirror surface of the polygon mirror 67 and the image forming surface have an optically conjugate positional relationship in the sub-scanning direction by the fθ lens 68, the field lens 71, and the cylindrical lens 73. The scanning position shift of the laser beam due to the tilting of the mirror surface from the vertical axis due to the processing error of each mirror surface is corrected.

A start sensor 7 is provided between the field lens 71 and the cylindrical lens 73 described above.
5 is provided with a mirror (not shown) for guiding the laser beam.

Here, the start sensor 75 will be described with reference to FIG. FIG. 2A shows a start sensor 75.
FIG. 2B is a diagram showing a detection waveform of the start sensor 75 when laser beams having different light amounts are respectively received, and FIG. 2C is a perspective view showing the configuration of FIG.
FIG. 2B is a diagram showing the output timing of the scanning start signal a when the laser beam having the light amount Pa shown in FIG. 2B is received, and FIG. 2D shows the light amount Pb shown in FIG. 2B (light amount Pb> light amount). FIG. 7 is a diagram illustrating output timing of a scanning start signal a when a laser beam of Pa) is received. Start sensor 7
5 has a light receiving surface 75a for receiving a laser beam scanned in the x direction, as shown in FIG. The width of the light receiving surface 75a in the x direction through which the laser beam passes is formed, for example, larger than the spot diameter (20 μm) of the laser beam. The start sensor 75 is, for example, as shown in FIG.
When a laser beam having the light amount Pa shown in FIG.
As shown in FIG. 2C, the scan start signal a is output at time t2 when the detection voltage reaches the threshold. FIG. 2 (b)
When a laser beam having the light amount Pb shown in FIG.
As shown in (d), the time t when the detection voltage reaches the threshold value
At 1 (time earlier than time t2), a scan start signal a is output. Thus, the start sensor 75 detects the start of scanning of the laser beam in the main scanning direction (x direction).
The scanning start signal a output from the start sensor 75 is
This is given to a drawing control unit 102 described later, and drawing is started after a predetermined time from that point.

Next, the data processing unit 101 and the drawing control unit 1
02 will be described with reference to FIG. FIG. 3 is a block diagram showing a schematic configuration of the printed wiring board manufacturing apparatus. The data processing unit 101 receives artwork data of a printed wiring board designed using CAD and converts the artwork data into run-length data for raster scan drawing. As the data processing unit 101, for example, a workstation or a personal computer is used.

The drawing control unit 102 includes a light amount distribution calculating unit 89
, A run-length data buffer 112, a raster conversion circuit 113, a drawing data buffer memory 114, and a drawing processing unit 115.

As shown in FIG. 1, for example, a light receiving sensor 88 for measuring the light intensity of the laser beam is movable at the tip of the mounting table 15 in the sub-scanning direction in the main scanning direction (x direction). It is provided in. Before starting laser drawing on the printed wiring board S, the mounting table 15 is moved so that the light receiving sensor 88 is located at the processing position PY. In this state, the laser beam is irradiated sequentially at predetermined intervals in the main scanning direction in the drawing effective range, and the light receiving sensor 88 is appropriately moved to the spot position of the laser beam so as to receive the laser beam. The measured light intensity data (multi-value light amount data) is output to the light amount distribution calculation unit 89. In this way, the light intensity distribution of the laser beam at predetermined intervals in the main scanning direction is measured. The light amount distribution calculation unit 89 is based on these multi-value light amount data of the laser beam measured by the light receiving sensor 88,
Light amount correction data c for correcting unevenness in the light amount of the laser beam is calculated, and the calculated light amount correction data c is output to the main controller 121 of the drawing processing unit 115.

The run-length data buffer 112 temporarily stores all the run-length data converted by the data processing unit 101. The raster conversion circuit 113 converts the sequentially read run-length data into binary raster data in pixel units. Drawing data buffer memory 114
Stores raster data for each scan. The drawing processing unit 115 gives a raster conversion instruction to the raster conversion circuit 113, reads out the raster data stored in the drawing data buffer memory 114 with the drawing clock signal d from the internal drawing clock generation circuit 122, and converts the raster data into The voltage (amplitude) of the drawing signal e generated based on the light amount is corrected based on the light amount correction data c from the light amount distribution calculating unit 89, and the corrected drawing signal f is output to the acousto-optic modulator 53. The acousto-optic modulator 53 modulates (light intensity modulation) the laser beam from the laser light source 41 based on the corrected drawing signal f.

The drawing processing unit 115 includes a main controller 121, a drawing clock generation circuit 122, a light amount correction circuit 123, a polygon rotation control unit 124, and a Y-axis synchronization control unit 125.

The main controller 121 includes light amount correction data c calculated by the light amount distribution calculator 89, a scan start signal a detected by the start sensor 75 for each scan,
Surface signal i from polygon surface detector 126 (signal indicating surface of polygon mirror 67 irradiated with laser beam)
Is entered. The main controller 121 controls the light amount correction circuit 123 based on the drawing clock signal d from the drawing clock generation circuit 122 and the light amount correction data c from the light amount distribution calculation unit 89, and controls the polygon rotation control unit 12
4 and the Y-axis synchronization control unit 125.

The polygon surface detector 126 detects the surface of the polygon mirror 67 irradiated with the laser beam. This polygon surface detector 126
For example, the mark formed on the polygon mirror 67 is optically detected to detect the first surface of the polygon mirror 67, and the remaining second to n-th surfaces of the polygon mirror 67 are shown in FIG. As described above, the scanning start signal a from the start sensor 75 is detected by counting by the counter unit 126a.

The drawing clock generating circuit 122 generates a drawing clock signal d and outputs it to the drawing data buffer memory 114 and the main controller 121 as shown in FIG. The polygon rotation control unit 124 controls the rotation of the polygon mirror 67 according to an instruction from the main controller 121. The Y-axis synchronization control unit 125 drives and controls the drawing stage 5 in the y-axis direction in synchronization with laser drawing according to an instruction from the main controller 121.

The light amount correction circuit 123 is provided for each laser beam as shown in FIG. FIG. 4 is a block diagram illustrating a configuration of a main part of the drawing control unit. The drawing signal e generated based on the raster data of each beam read from the drawing data buffer memory 114 is input to the corresponding light amount correction circuit 123 for each beam. These light amount correction circuits 123 correct the input drawing signal e based on the light amount correction data c set for themselves, and output the corrected drawing signal f to the acousto-optic modulator 53.
Respectively. These light quantity correction circuits 123
A light quantity correction memory 131, a reference voltage output circuit 132,
A light amount control circuit 133 is provided. The main controller 121 stores the light amount correction data c for each beam from the light amount distribution calculator 89 in the corresponding light amount correction memory 1.
31 is set for each beam. Here, the light amount correction data c is for correcting the light amount control voltage setting (multi-value light amount setting value) which is the amplitude of the drawing signal.

The light amount correction memory 131 stores and holds a light amount correction value at a correction position in one scanning line of the laser beam as light amount correction data c. Reference voltage output circuit 132
Generates a reference voltage h for light quantity correction according to the light quantity correction data c read from the light quantity correction memory 131.
The light quantity control circuit 133 corrects the light quantity control voltage setting (multi-value light quantity set value) in the drawing signal e according to the light quantity correction reference voltage h from the reference voltage output circuit 132, and the corrected drawing signal f is output to the acousto-optic modulator 53.
The reference voltage output circuit 132 converts, for example, the light amount correction data c, which is digital data read from the light amount correction memory 131, into a reference voltage h for light amount correction, which is analog data, and outputs the D / A. (Digital-analog) converters and the like. Also, the light amount control circuit 1
33, for example, the drawing data buffer memory 11
4 is a digital data for generating a drawing signal by converting the raster data read out from the data No. 4 into a multi-valued data. D / A that corrects according to voltage h and outputs a drawing signal that is analog data after the correction
(Digital-analog) converters and the like.

In accordance with the drawing signal f corrected by each light amount control circuit 133, the corresponding laser beam is modulated, and each modulated laser beam is irradiated on the printed wiring board S to correct the light amount unevenness and correct the density. A drawing pattern in which unevenness has been corrected is formed on the printed wiring board S.

The above-mentioned light amount correction circuit 123 corresponds to the light amount adjusting means in the present invention, the above-mentioned light amount correction memory 131 corresponds to the memory section in the present invention, and the above-described reference voltage output circuit 132 and light amount control circuit 133. Correspond to the adjustment unit in the present invention.

Here, a multi-beam configuration in this embodiment will be described. In order to eliminate mutual interference of laser beams, the multi-beams are arranged so as to be oblique to the scanning line. That is, the distance between adjacent beams in the main scanning direction (x direction) is adjusted to be about 100 μm, and the distance between adjacent beams in the sub scanning direction (y direction) is adjusted to be 5 μm in units of pixels for raster drawing. . Accordingly, the distance between the beam centers of CH (channel) 1 to CH8 in the eight beams is approximately 700 μm in the x direction and 35 μm in the y direction.

Subsequently, in the printed wiring board manufacturing apparatus according to the embodiment having the above-described configuration, the above-described first to fourth correction examples will be sequentially described.

<First Correction Example> Here, in the printed wiring board manufacturing apparatus of the embodiment having the above configuration, the laser beam (for example, CH
An operation (first correction function) for correcting the density unevenness of the drawing pattern caused by the uneven light amount of the (one laser beam) will be described.

Before starting the laser drawing on the printed wiring board S, the calculation and the setting of the light quantity correction data c are performed as follows. First, as shown in FIG. 1, the drawing stage 5 is moved so that the light receiving sensor 88 is positioned at the processing position PY.
Is moved. In this state, the light receiving sensor 88 is sequentially moved in the main scanning direction at intervals of 10 mm in the laser beam drawing effective range, and the light receiving sensor 88 is appropriately irradiated with the laser beam (CH1), and the light intensity data ( Multi-level light quantity data) and measures the light quantity distribution calculation unit 8
9 (see FIG. 3). In this way, the light intensity distribution of the laser beam (CH1) at every 10 mm in the main scanning direction is measured. The light amount distribution calculation unit 89 includes the light receiving sensor 8
8, light amount correction data c for correcting unevenness in the light amount of the laser beam (CH1) is calculated based on the multilevel light amount data of the laser beam (CH1), and the calculated light amount correction data c is drawn. Output to the main controller 121 of the unit 115. Specifically, based on the light intensity distribution of the laser beam (CH1) measured at intervals of 10 mm, for example, 32 pixels (32 × 5 pixels) such that the light amount of the laser beam (CH1) is constant over one scanning line. μm =
2500 light correction data c per unit (160 μm) (scan width
It is calculated over 400 mm / 32 pixels (160 μm) = 2500 pixels. The light amount distribution calculation unit 89 calculates as described above.
The 2500 light quantity correction data c in units of 32 pixels are output to the main controller 121. Main controller 1
21 sets the 2500 light quantity correction data c in units of 32 pixels in the light quantity correction memory 131 of the light quantity correction circuit 123.

The light amount correction circuit 123 is a light amount correction memory 1
The light amount correction data c of 2500 pixels, which is set to 31 and extends in units of 32 pixels, is written in address order in the drawing clock generation circuit 122.
Is read out in a correction unit obtained by dividing 32 clocks and output to the reference voltage output circuit 132. The reference voltage output circuit 132 generates a reference voltage h for light quantity correction in accordance with 2500 light quantity correction data c in units of 32 pixels read out from the light quantity correction memory 131 in order of addresses and outputs the reference voltage h to the light quantity control circuit 133. Light intensity control circuit 1
Reference numeral 33 denotes a reference voltage output circuit which sets the light amount control voltage setting (multi-value light amount setting value) of the drawing signal e generated based on the CH1 raster data read from the drawing data buffer memory 114 by the drawing clock signal d. 132 is corrected according to the reference voltage h for light amount correction from CH 132, and the corrected CH
1 is output to the acousto-optic modulator 53. In this way, according to the 2500 light quantity correction data c in units of 32 pixels, the corrected drawing signal f of one scan line sequentially adjusted to the desired light quantity control voltage setting is output by the acousto-optic modulator. It is output to 53.

The acousto-optic modulator 53 outputs the corrected CH
The laser beam (CH1) is modulated (light intensity modulation) based on the drawing signal f of No. 1. Modulated laser beam (CH
1) is applied to the printed wiring board S, and a drawing pattern without density unevenness is formed on the printed wiring board S.
The drawing pattern by the laser beam (CH1) is shown in FIG.
As shown in (b), the corrected CH1 corrected based on the light amount correction data c from the main controller 121.
The density unevenness is corrected by the drawing signal f. FIG.
5A is a view showing that density unevenness occurs in a drawing pattern due to uneven light amount of the laser beam (CH1) in one scan of the scanning optical system, and FIG.
FIG. 4 is a diagram in which the density unevenness of the drawing pattern shown in FIG.

As shown in FIG. 5 (a), even if the drawing signal e of CH1 in the uncorrected state is set to a desired constant light amount in one scanning period, the laser beam in one scanning of the scanning optical system is changed. Power efficiency varies,
It will occur light quantity unevenness in light amount distribution L ₁ of the laser beam (CH1) This variation, so that the drawing pattern P ₁ having a density unevenness is formed. Yes The drawing pattern P _1, for example, the concentration is higher portion D _1, and partial D ₂ is a desired concentration, and low concentration portions D _3, and the portion D ₃ than the concentration is lower portions D ₄ And uneven density occurs.

Therefore, in the present embodiment, as shown in FIG. 5B, the CH1 in the uncorrected case shown in FIG.
Is corrected based on the light amount correction data c from the light amount distribution calculating unit 89, and the corrected drawing signal f of CH1 is output to the acousto-optic modulator 53, so that one scan of the scanning optical system can be performed. the laser beam the light intensity distribution L ₁ of the laser beam (CH1) with a light amount unevenness is corrected to the light amount distribution L ₂ becomes constant amount due to variations in the power efficiency, to form a free drawing pattern P ₂ density unevenness in. The drawing pattern P ₂ is uniformly formed at a portion D ₂ is a desired concentration. Here, the laser beam (CH
Although 1) has been described as an example, density unevenness correction can be similarly performed for CH2 to CH8.

As described above, since the light amount correction circuit 123 can adjust the light amount at the correction position in one scanning line of the laser beam according to the light amount correction data c, the laser light in one scanning of the scanning optical system can be adjusted. It is possible to accurately correct unevenness in the light amount of the laser beam caused by variations in the power efficiency of the beam, and to accurately correct unevenness in density of a writing pattern, thereby realizing high-quality writing.

<Second Correction Example> Subsequently, in addition to the above-described first correction function, the density unevenness of the drawing pattern for each polygon surface caused by the variation in the reflectance of each reflecting mirror (polygon surface) of the polygon mirror 67 is determined. Correction operation (second correction function)
Will be described.

The apparatus according to the present embodiment is designed to correct the laser beam for each surface of the polygon mirror 67 in order to correct the uneven density of the drawing pattern for each polygon surface due to the variation in the reflectance of each reflecting mirror (polygon surface) of the polygon mirror 67. Light receiving sensor 88 for detecting the light amount of the beam and polygon surface detector 126
And a light amount distribution calculation unit 89 for calculating light amount correction data c for each surface of the polygon mirror 67 so that the light amount of the laser beam on each surface of the polygon mirror 67 is constant.

The light receiving sensor 88 and the polygon surface detector 126 correspond to the light amount detecting means in the present invention.
The light amount distribution calculation unit 89 corresponds to a calculation unit in the present invention.

Before starting the laser drawing on the printed wiring board S, the amount of the laser beam for each surface of the polygon mirror 67 is detected, and the detected amount of the laser beam for each surface of the polygon mirror 67 is kept constant. The calculation of the light amount correction data c for each surface of the polygon mirror 67 and the setting of the calculated light amount correction data c for each surface of the polygon mirror 67 in the light amount correction memory 131 are performed as follows. Do.

First, as shown in FIG.
Is moved so that is positioned at the processing position PY. In this state, the light receiving sensor 88 and the polygon surface detector 126 detect the light amount of the laser beam for each surface of the polygon mirror 67. For example, as shown in FIG. 3, the main controller 121 detects the first surface of the polygon mirror 67 based on the surface signal i from the polygon surface detector 126, and draws a laser beam by the first surface of the polygon mirror 67. The laser beam is controlled so as to be sequentially irradiated at intervals of 10 mm in the main scanning direction from the reference position to the drawing end position, and the light receiving sensor 88 is sequentially moved to the position of the spot of the laser beam to be irradiated so that the laser beam is irradiated. Control is performed to receive light as appropriate. Thus, the light intensity data (multi-value light amount data) measured for the first surface of the polygon mirror 67 is used as the light amount distribution calculating unit 89.
Is output to In addition, the remaining second of the polygon mirror 67
The light intensity data (multi-value light amount data) for the surfaces from the surface to the n-th surface are also output to the light amount distribution calculation unit 89 in the same manner as described above, and the light amounts of the laser beams on the second to n-th surfaces of the polygon mirror 67 are also detected. Is done.

The light amount distribution calculator 89 calculates the light intensity distribution data (multi-value light amount data) of the laser beams on all the surfaces of the polygon mirror 67 detected as described above. Light amount correction data c for each surface of the polygon mirror 67 for correcting the light amount of the laser beam so that the light amount of the laser beam on the first surface to the n-th surface is constant is calculated. Specifically, based on the light intensity data (multi-value light amount data) of each laser beam measured at every 10 mm interval for all the surfaces (first surface to n-th surface) of the polygon mirror 67 as described above. Polygon mirror 6
In order to make the light amount of the laser beam on all the surfaces of 7 constant, 2501 (2501 scanning widths of 400 mm / 32 pixels, 160 μm = 2500 and adding one start sensor 75) 32 The light amount correction data c for each pixel is calculated for each surface of the polygon mirror 67. The light amount distribution calculation unit 89 outputs the light amount correction data c for each pixel of the polygon mirror 67 calculated in the above manner in units of 32 pixels over 2501 units to the main controller 121.

The main controller 121 is shown in FIG.
Thus, for each surface of the polygon mirror 67, 2501
Light amount correction data c (c₀~ C_end)
Is set in the light quantity correction memory 131. This light intensity correction memo
From the first surface to the n-th surface of the polygon mirror 67,
Each time, a memory address from "0" to "end"
There are provided 2501 divided recording areas. n
Calculate as above for each recording area that covers
The output light amount correction data c for each 32 pixels is set.
Is defined. However, if the memory address is "end"
The recording area is located on the next surface of the polygon mirror 67.
Initial value (used first on the next surface of polygon mirror 67)
Light intensity correction in units of 32 pixels for power start sensor 75
Data c _end) Is recorded.

As described above, the light amount correction data c (c ₀ -c) for each surface of the polygon mirror 67 to the light amount correction memory 131.
After the setting of c _end ) is completed, laser drawing on the printed wiring board S is started.

Next, the operation of laser writing on the printed wiring board S will be described. As shown in FIG. 7, the main controller 121 specifies a surface to be irradiated with a laser beam from among the surfaces of the polygon mirror 67 based on the surface signal i from the polygon surface detector 126. The main controller 121 controls the light amount correction data c _{end in} units of 32 pixels recorded in the recording area of the memory address “end” on the surface before the specified surface.
, And then the memory addresses “0”, “1”, “2”,.
The light amount correction data c (c ₀ , c ₁ , c ₂ ,...) Recorded in the recording area in the order of 32 pixels is read out and output to the reference voltage output circuit 132. 131 is controlled. The light amount correction data c _{0 to} c _{end in} units of 32 pixels are supplied to the light amount correction memory 131 in accordance with the read clock signal g generated every 32 clocks of the drawing clock signal d in synchronization with the scanning start signal a.
And output to the reference voltage output circuit 132.

The reference voltage output circuit 132 generates a reference voltage h for light amount correction in accordance with light amount correction data c (c _{0 to} c _end ) in units of 32 pixels read from the light amount correction memory 131 in the order of memory addresses. Output to the light amount control circuit 133. The light-amount control circuit 133 outputs a light-amount control voltage setting (multi-value light-amount setting value) of the drawing signal e generated based on the raster data read out from the drawing data buffer memory 114 by the drawing clock signal d, to a reference voltage output. Circuit 1
Correction is performed in accordance with the reference voltage h for light amount correction from the light source 32, and the corrected drawing signal f is output to the acousto-optic modulator 53.

Accordingly, as shown in FIG. 7, the voltage value of the corrected drawing signal f is 32 in accordance with the polygon surface.
It is adjusted to a desired multi-level light quantity set value for each pixel. Specifically, the multi-level light amount set value of the drawing signal e generated based on the raster data from the drawing data buffer memory 114 is stored in the polygon first surface in the light amount correction data c _end corresponding to the polygon first surface. , C ₀ , c ₁ , c ₂ , ...
The correction is performed for every 32 pixels in the order of _，, c _end−1 , and a laser beam modulated by the corrected drawing signal f is applied. Similarly to the above, the multi-level light amount setting value of the drawing signal e generated based on the raster data from the drawing data buffer memory 114 is corrected for the polygon second surface to the polygon n-th surface. A laser beam corrected by data and modulated (light intensity modulated) by the corrected drawing signal f is applied.

As described above, the light amount of the laser beam for each surface of the polygon mirror 67 is detected by the light receiving sensor 88 and the polygon surface detector 126, and the laser light of each surface of the polygon mirror 67 is detected by the light amount distribution calculator 89. Light amount correction data c (c _{0 to} c _end ) for each surface of the polygon mirror 67 is calculated so that the light amount of the beam is constant, and the calculated light amount correction data c (c for each surface of the polygon mirror 67 is calculated. ₀
To c _end ) are set in the light amount correction memory 131 by the main controller 121, and the light amount correction circuit 123 sets the light amount correction data c (c _{0 to} c _end ) for each surface of the polygon mirror 67 set in the light amount correction memory 131. And the laser beam is modulated by the corrected drawing signal f. Therefore, the light amount of the laser beam on each surface of the polygon mirror 67 can be made constant. It is possible to correct unevenness in the light amount of the laser beam for each polygonal surface caused by variation in the reflectance of each reflecting mirror (polygonal surface), and to correct unevenness in the density of the drawing pattern.

<Third Correction Example> Next, an operation (third correction function) for correcting the density unevenness of the drawing pattern for each laser beam caused by the variation in the light amount for each laser beam will be described.

The apparatus of this embodiment is provided with a light amount correction circuit 123 for each laser beam as shown in FIG. 4 in order to correct the density unevenness of the drawing pattern for each laser beam due to the variation in the light amount for each laser beam. ing.

For example, the variation in the amount of light for each laser beam is caused by the variation in power efficiency for each laser beam in the scanning optical system. Specifically, even when the output of the laser light source is constant and the main scanning speed of the beam spot is controlled to be constant, factors in the optical path from the laser light source to the printed circuit board (for example, an acousto-optic modulator) The power efficiency of each laser beam varies due to the dispersion of the optical characteristics of each of the 53 laser beams, the dispersion of the reflectance in the irradiation range of each laser beam on the polygon surface, and the like. Due to the variation in power efficiency of each laser beam of the scanning optical system, the laser beam intensity varies for each laser beam, and the density unevenness occurs in the drawing pattern for each laser beam. I have. Here, calibration is performed in such a case.

Before starting laser writing on the printed wiring board S, calculation and setting of the light quantity correction data c for each laser beam are performed as follows. First, as shown in FIG. 1, the drawing stage 5 is moved so that the light receiving sensor 88 is located at the processing position PY. In this state, the light receiving sensor 88 is sequentially moved in the main scanning direction at intervals of 10 mm in the laser beam drawing effective range, and the light receiving sensor 88 is appropriately irradiated with the laser beam (CH1) to thereby obtain the light intensity (multiple). Value light quantity data) and outputs it to the light quantity distribution calculation unit 89 (see FIG. 3). In this way, the light intensity distribution of the laser beam (CH1) at every 10 mm in the main scanning direction is measured. The remaining laser beams (CH2 to CH8) were measured in the same manner as described above, and the laser beams (CH2 to CH8) were measured in the main scanning direction.
The light intensity distribution is measured at intervals of 10 mm.

The light quantity distribution calculator 89 controls the light quantity of the laser beam of all CHs based on the multi-level light quantity data of the laser beam for all CHs (CH1 to CH8) measured by the light receiving sensor 88. The light amount correction data c for each laser beam is calculated, and the calculated light amount correction data c for each laser beam is
Output to 1. Specifically, based on the light intensity distribution of the laser beam for all CHs measured at 10 mm intervals for each laser beam for each CH, the laser beam for each CH is controlled so that the light amount of the laser beam for all CHs becomes constant. For example, 32 pixels (32
× 5 μm = 160 μm) 2500 light intensity correction data c per unit
The calculation is performed over the entire number (scanning width 400 mm / 32 pixels (160 μm) = 2500). The light quantity distribution calculator 89 outputs the light quantity correction data c (8 beams × 2500 = 20000) for each laser beam calculated as described above to the main controller 121.

The main controller 121 converts the light amount correction data c (8 beams × 2500) for each laser beam into
Light amount correction circuit 123 corresponding to each laser beam
Is set in the light amount correction memory 131 of FIG.

Each of the light quantity correction circuits 123 converts the 2500 light quantity correction data c set in its own light quantity correction memory 131 in units of 32 pixels into a drawing clock signal d from the drawing clock generating circuit 122 in the order of 32 clocks. The data is read out by the divided correction unit and output to the reference voltage output circuit 132. The reference voltage output circuit 132 is a light amount correction memory 1
A reference voltage h for light amount correction is generated and output to the light amount control circuit 133 in accordance with the light amount correction data c in units of 32 pixels, which is read out from 31 and in the order of 2500 addresses in 2500 units. The light amount control circuit 133 uses the light amount control voltage setting (multi-value light amount setting value) of the drawing signal e generated based on the corresponding raster data read from the drawing data buffer memory 114 by the drawing clock signal d as a reference. Voltage output circuit 132
The correction is performed in accordance with the reference voltage h for correcting the light amount from the controller, and the corrected drawing signal f is output to the acousto-optic modulator 53. In this way, the corrected drawing signal f for each laser beam sequentially adjusted to a desired light amount is output to the acousto-optic modulator 53 according to the light amount correction data c for each laser beam.

The acousto-optic modulator 53 modulates the corresponding laser beam (light intensity modulation) based on the corrected drawing signal f for each laser beam. The modulated laser beams (CH1 to CH8) are irradiated on the printed wiring board S, and a drawing pattern without density unevenness is formed on the printed wiring board S for each laser beam.

For example, as shown in FIG. 8B, the drawing pattern of the CH1 and CH2 laser beams is corrected for the uneven density by the corrected CH1 and CH2 drawing signals f ₁ and f ₂ . FIG. 8A is a view showing that density unevenness occurs in a drawing pattern due to uneven light amount of each laser beam, and FIG. 8B is a view showing density unevenness of the drawing pattern shown in FIG. FIG.

As shown in FIG. 8A, even if the drawing signal e of CH1 and CH2 in the uncorrected state is set to a desired constant light amount in one scanning period, each of the laser beams of the scanning optical system has If there is a variation in the power efficiency, the variation causes a light amount distribution L _CH1 of the laser beam (CH1).
And the light amount distribution L _CH2 of the laser beam (CH 2), and the drawing pattern P _CH having the density unevenness is formed for each laser beam. The drawing pattern P _CH includes, for example, a portion D ₀ having the highest density,
The next highest concentration D ₁ (D ₀ > D ₁ > D ₂ );
A portion D ₂ having a desired concentration, a portion D ₃ having a low concentration,
A portion D ₄ having a lower concentration than the portion D ₃ ,
Density unevenness has occurred.

Therefore, in this embodiment, as shown in FIG. 8B, the uncorrected CH shown in FIG.
1 and CH2 are corrected based on the corresponding light amount correction data c, and the corrected signals CH1 and C2 are corrected.
By outputting the drawing signals f ₁ and f ₂ of H2 to the acousto-optic modulator 53, the laser beam (CH) having uneven light amount due to variation in power efficiency of each laser beam of the scanning optical system.
1, the light intensity distribution L _CH1, L _CH2 of CH2) corrected to the light amount distribution L becomes constant amount, no density irregularities drawing pattern P
_CH 'is forming. This drawing pattern P _CH ′ is formed uniformly in a portion D ₂ having a desired density.

As described above, since the light amount correction circuit 123 is provided for each of a plurality of laser beams to be simultaneously scanned and drawn, even in multi-beam drawing using a plurality of laser beams, one laser beam can be scanned within one scan. In this case, the density unevenness of the writing pattern can be corrected with high accuracy, the variation in the amount of light for each laser beam can be corrected with high accuracy, and the density unevenness of the writing pattern for each laser beam can be corrected with high accuracy.

In the third correction example, the light amount correction memory 131, the reference voltage output circuit 132, and the light amount control circuit 13
3 is provided for each laser beam. However, if the variation in the amount of light for each laser beam is not a problem, as shown in FIG. It suffices that only the light amount control circuit 133 constitutes 123 and only a single light amount correction memory 131 and a single reference voltage output circuit 132 are provided. In this case, since the variation of the light amount for each laser beam does not matter, it is only necessary to measure the light amount distribution of any one beam, and the measurement of the light amount distribution of all the beams can be omitted. The main controller 121 outputs the reference voltage h for light quantity correction from the reference voltage output circuit 132 with a delay of the beam CH interval time for each laser beam.

<Fourth Correction Example> Subsequently, the start sensor 7
The operation (fourth correction function) of correcting the displacement of the drawing pattern caused by the fluctuation in the light amount of the laser beam to the position 5 will be described.

The apparatus according to the present embodiment controls the start sensor 75 so that the amount of light received by the start sensor 75 becomes constant in order to correct the displacement of the drawing pattern caused by the fluctuation in the light amount of the laser beam to the start sensor 75. And a light amount distribution calculator 89 for adjusting the light amount of the laser beam. Further, in order to change the light amount of the laser beam according to the type of the printed wiring board S, a function of adjusting the light amount of the laser beam applied to the printed wiring board S according to the type of the printed wiring board S to be drawn is provided. The main controller 121 is also provided. The type of the printed wiring board S is classified according to the sensitivity characteristics of the printed wiring board S.

The above-mentioned light amount distribution calculating section 89 corresponds to the start sensor light amount adjusting means in the present invention.

Next, the operation of the apparatus of this embodiment for correcting the displacement of the drawing pattern caused by the fluctuation of the amount of light to the start sensor 75 will be described.

In the above-described second correction example, the light amount correction data c (c ₀₎ in the effective drawing range of the laser beam.
Since the calculation of .about.c _end-1 ) and its setting in the light amount correction memory 131 have already been described, here, the light amount correction data c _end for adjusting the light amount of the laser beam to the start sensor 75 is described here. The calculation and the setting of the calculated light amount correction data _{cend in} the light amount correction memory 131 will be described.

The light quantity distribution calculator 89 calculates the light quantity correction data c (c ₀ -c) in the effective drawing range of the laser beam.
In calculating c _end-1 ), light amount correction data c _end for correcting the light amount of the laser beam to the start sensor 75 to a desired constant value is also calculated. This light quantity correction data c
_{The end} is determined in consideration of a variation in the light amount of each polygon surface of the laser beam such that the amount of the laser beam received by the start sensor 75 becomes a desired constant value. The light quantity distribution calculator 89 outputs the light quantity correction data c (c _{0 to} c _end ) calculated in this way to the main controller 121. The main controller 121 sets the light amount correction data c (c _{0 to} c _end ) in the light amount correction memory 131 in order of addresses.

Next, the operation of laser writing on the printed wiring board S will be described. As shown in FIG. 7, the main controller 121 specifies a surface to be irradiated with a laser beam from among the surfaces of the polygon mirror 67 based on the surface signal i from the polygon surface detector 126. The main controller 121 controls the light amount correction data c _{end in} units of 32 pixels recorded in the recording area of the memory address “end” on the surface before the specified surface.
, And then the memory addresses “0”, “1”, “2”,.
The light amount correction data c (c ₀ , c ₁ , c ₂ ,...) Recorded in the recording area in the order of 32 pixels is read out and output to the reference voltage output circuit 132. 131 is controlled. The light amount correction data c _{0 to} c _{end in} units of 32 pixels are supplied to the light amount correction memory 131 in accordance with the read clock signal g generated every 32 clocks of the drawing clock signal d in synchronization with the scanning start signal a.
And output to the reference voltage output circuit 132.

The reference voltage output circuit 132 responds to the light quantity correction data c (c _end , c ₀ , c ₁ , c ₂ ,..., C _{end -1} ) read out from the light quantity correction memory 131 in units of 32 pixels. Then, a reference voltage h for light quantity correction is generated and output to the light quantity control circuit 133. The light amount control circuit 133 outputs a reference voltage output (multi-value light amount setting value) for light amount control of the drawing signal e generated based on the raster data read from the drawing data buffer memory 114 by the drawing clock signal d. The correction is performed according to the reference voltage h for light quantity correction from the circuit 132, and the corrected drawing signal f is output to the acousto-optic modulator 5.
Output to 3.

Therefore, the corrected drawing signal f is
As shown in FIG. 7, a desired multi-level light quantity setting value is adjusted every 32 pixels. Specifically, the multi-level light amount set value of the drawing signal e generated based on the raster data from the drawing data buffer memory 114 is stored in the first polygon surface in the light amount correction data c corresponding to the first polygon surface. _end , c
_{0, c 1, c 2,} ···, corrected to 32 for each pixel in the order of c _{end- 1,} a laser beam modulated (intensity modulation) in this corrected drawing signal f is irradiated. Light intensity correction data c _end
The laser beam modulated by the drawing signal f corrected by the above is irradiated to the start sensor 75 during the scanning invalid period, and the light amount correction data c ₀ , c ₁ , c ₂ ,..., C
_The laser beam modulated by the drawing signal f corrected at _end-1 is sequentially applied to the drawing effective area of the printed wiring board S. Also on the polygon second surface to polygon n-th surface, a laser beam whose light amount has been corrected in the same manner as described above is applied to the start sensor 75 and the printed wiring board S in this order. As can be understood from the drawing surface and the actual light amount distribution at the start sensor 75 shown in FIG.
Is constant regardless of the polygon surface, and the jitter of the scanning start signal a does not occur for each polygon surface, and the drawing start position can be made constant for each polygon surface. Therefore, the problem that the drawing pattern is displaced for each polygon surface can be solved.

Here, a case where laser drawing is performed on printed wiring boards S of different types having different sensitivity characteristics will be described.

The main controller 121 adjusts the light amount of the laser beam itself according to the type of the printed wiring board S having a different sensitivity characteristic to be drawn, and also adjusts the light amount correction data c _end from the light amount distribution calculator 89.
To adjust. More specifically, the light amount in the laser beam drawing effective range is adjusted so that the light amount of the laser beam becomes the light amount required for the printed wiring boards S of different types having different sensitivity characteristics to be drawn. the controller 121 adjusts the light quantity correction data c _{end the} as the amount of light received by the start sensor 75 is constant irrespective of the type of the printed circuit board S. The light amount correction data c thus adjusted according to the type of the printed wiring board S
_{The end} is set in the light quantity correction memory 131. The light amount correction data c (c
The processing after the reading of _{0 to} c _end ) is performed in the same manner as described above, and the laser drawing is performed with the laser beam modulated by the corrected drawing signal.

As described above, since the light amount distribution calculating unit 89 for adjusting the light amount of the laser beam to the start sensor 75 is provided so that the amount of light received by the start sensor 75 becomes constant, Even when the light amount of the laser beam is changed, the amount of light received by the start sensor 75 can be kept constant, and the jitter (position shift) of the scan start signal a at the start sensor 75 due to the fluctuation of the light amount of the laser beam can be maintained. ) Can be prevented, and the drawing start position can be prevented from shifting, so that the writing pattern can be prevented from shifting.
Therefore, even for a wide variety of printed wiring boards S having different photosensitive characteristics, laser writing can be performed with high accuracy without causing density unevenness or positional deviation in the drawn pattern, and the range of use can be expanded.

The present invention can be modified as follows.

(1) In the above-described embodiment, the run length data and the raster data containing only the on / off information of the drawing are used. However, the run length data and the raster data containing the on / off information and the gradation information are used. Can also be used. When the latter is used, when a drawing signal is generated based on raster data, the light amount control voltage setting (multi-value light amount set value) is determined based on the gradation information.

(2) In the above embodiment, the laser light source 41 and the acousto-optic modulator 53 are used, but a laser diode may be used instead. In this case, the on / off control of the laser diode may be directly performed, and the structure can be simplified.

(3) In the above embodiment, the imaging optical system 2
1 was fixed and the drawing stage 5 was moved,
Conversely, the present invention is applicable to a configuration in which the imaging optical system 21 moves.

(4) In the above-described embodiment, the light amount correction data c in units of 32 pixels stored in the light amount correction memory 131 is read out in address units in units of 32 pixels and output to the reference voltage output circuit 132. , Reference voltage output circuit 13
2 only when the light amount correction data c is changed to 2.
Light amount correction memory 131 stores light amount correction data c in units of 32 pixels.
And may be set in the reference voltage output circuit 132. Further, although the light quantity correction data c is set to a unit of 32 pixels, the light quantity correction data c is not limited to the unit of 32 pixels, and may be handled as a unit other than 32 pixels.

(5) In the above-described embodiment, a printed wiring board manufacturing apparatus has been described as an example. However, the present invention is not limited to such an apparatus, and an apparatus for performing an exposure process using a laser beam. Applicable to

[0097]

As is apparent from the above description, according to the first aspect of the present invention, there is provided the light amount adjusting means for adjusting the light amount of the correction portion in one scanning line according to the light amount correction data. Therefore, the unevenness in the amount of the laser beam in one scan of the scanning optical system can be corrected with high accuracy, and the unevenness in density of the drawing pattern can be corrected with high accuracy, and high-quality drawing can be realized.

According to the second aspect of the present invention, the light amount adjusting means includes: a memory unit for holding a light amount correction value of a correction portion in one scanning line of the laser beam as light amount correction data; An adjustment unit that adjusts the light amount of the laser beam according to the light amount correction value from the unit enables highly accurate correction of the density unevenness of the drawing pattern caused by the uneven light amount of the laser beam in one scan of the scanning optical system. Can be realized.

According to the third aspect of the present invention, since the light amount adjusting means is provided for each of a plurality of laser beams for simultaneous scanning and drawing, multi-beam drawing using a plurality of laser beams is also possible. The density unevenness of the drawing pattern in one scanning of each laser beam can be corrected with high accuracy, and furthermore, the unevenness of the density of the drawing pattern for each laser beam due to the variation in the light amount of each laser beam can be corrected with high accuracy.

According to the apparatus described in claim 4, the light quantity detecting means for detecting the light quantity of the laser beam for each face of the polygon mirror, and the laser light of each face of the polygon mirror detected by the light quantity detecting means. Calculation means for calculating light amount correction data for each surface of the polygon mirror so that the light amount of the beam is constant is provided, so that light amount correction data for each surface of the polygon mirror can be automatically calculated. According to the calculated light amount correction data for each surface of the polygon mirror, the light amount of the laser beam on each surface of the polygon mirror is adjusted to be constant. The variation in the light amount of the beam is corrected, and the density unevenness of the drawing pattern for each surface of the polygon mirror can be corrected with high accuracy.

According to the apparatus described in claim 5, the start sensor for detecting the start of the main scanning of the laser beam by receiving the laser beam, and the amount of light received by the start sensor is constant. The start sensor light amount adjusting means for adjusting the light amount of the laser beam to the start sensor is provided, so that even when the light amount of the laser beam is changed according to the type of the processing target, The amount of received light can be kept constant, and the jitter (positional deviation) of the scanning start signal at the start sensor due to the fluctuation of the amount of light can be prevented. Therefore, laser drawing can be performed with high accuracy even on a wide variety of types of processing objects, and the range of use can be expanded.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a printed wiring board manufacturing apparatus which is an example of a laser drawing apparatus according to the present invention.

2A is a perspective view illustrating a configuration of a start sensor, FIG. 2B is a diagram illustrating detection waveforms of the start sensor when laser beams having different light amounts are respectively received, and FIG. FIG. 4B is a diagram showing the output timing of the scanning start signal a when the laser beam having the light amount Pa shown in FIG. 4B is received, and FIG. 6D is a diagram showing the light amount Pb (light amount Pb) shown in FIG.
FIG. 7 is a diagram showing output timing of a scanning start signal a when a laser beam having a light amount (> Pa) is received.

FIG. 3 is a block diagram illustrating a schematic configuration of a printed wiring board manufacturing apparatus according to an embodiment.

FIG. 4 is a block diagram illustrating a configuration of a main part of a drawing control unit.

5A is a diagram illustrating density unevenness of a drawing pattern, and FIG. 5B is a diagram in which the density unevenness of the drawing pattern illustrated in FIG.

FIG. 6 is a diagram showing a light quantity correction memory map.

FIG. 7 is a timing chart showing timing for correcting raster data.

FIG. 8A is a diagram illustrating density unevenness of a drawing pattern due to uneven light amount of each laser beam, and FIG.
FIG. 4 is a diagram in which the density unevenness of the drawing pattern shown in FIG.

FIG. 9 is a block diagram showing a configuration different from the printed wiring board manufacturing apparatus of the embodiment.

[Explanation of symbols]

 3 Guide rail (moving means) 5 Drawing stage (mounting table) 7 Servo motor (moving means) 9 Feed screw (moving means) 41 Laser light source 53 Acousto-optic modulator 67 Polygon mirror (deflecting means) 73 ... cylindrical lens 75 ... start sensor 88 ... light receiving sensor (light amount detecting means) 89 ... light amount distribution calculating unit (calculating means) 121 ... main controller 122 ... drawing clock generating circuit 123 ... light amount correcting circuit (light amount adjusting means) 126 ... polygon Surface detector (light amount detecting means) 131: Light amount correction memory (memory unit) 132: Reference voltage output circuit (adjustment unit) 133: Light amount control circuit (adjustment unit) S: Printed wiring board (processing object) LB: Laser beam

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Akira Kuwahara 4-chome Tenjin Kitamachi 1-chome, Horikawa-dori-Terauchi, Kamigyo-ku, Kyoto F-term in Dainippon Screen Mfg. Co., Ltd. F-term (reference) 2C362 AA53 AA55 AA56 AA61 AA63 AA69 BA56 BA67 BB33 2H097 AA03 AB05 BA10 BB01 CA17 EA01 LA09 5C072 AA03 BA08 DA04 FB12 FB15 HA02 HA06 HA12 HB04 XA01 XA04

Claims (5)

[Claims] 1. A laser beam is modulated by a drawing signal generated based on raster data, and the modulated laser beam is deflected in a main scanning direction by a deflecting means to irradiate an object to be processed on a mounting table. A laser writing apparatus that draws a desired pattern on the processing object by relatively moving a laser beam and a mounting table in a sub-scanning direction by a moving unit; A laser writing apparatus comprising: a light amount adjusting unit that adjusts a light amount according to light amount correction data. 2. The laser writing apparatus according to claim 1, wherein the light amount adjusting unit includes: a memory unit that holds, as light amount correction data, a light amount correction value of a correction portion in one scanning line of the laser beam; A laser beam drawing apparatus comprising: an adjusting unit that adjusts the light amount of the laser beam according to the light amount correction value from the unit. 3. The laser writing apparatus according to claim 1, wherein the light amount adjusting means is provided for each of a plurality of laser beams for simultaneous scanning and writing. 4. The laser writing apparatus according to claim 1, wherein the deflecting unit is a scanning system including a polygon mirror, and detects a light amount of a laser beam for each surface of the polygon mirror. Light amount detecting means; and calculating means for calculating light amount correction data for each surface of the polygon mirror such that the light amount of the laser beam on each surface of the polygon mirror detected by the light amount detecting means is constant. Laser drawing apparatus. 5. The laser writing apparatus according to claim 1, wherein: a start sensor for detecting main scanning start of the laser beam by receiving the laser beam; A laser writing apparatus comprising: a start sensor light amount adjusting unit that adjusts the amount of a laser beam to the start sensor so that the amount of received light is constant.