JP5624580B2 - Image recording method and image recording system - Google Patents

Description

  The present invention relates to an image recording method and an image recording system for directly drawing a predetermined drawing pattern represented by digital data on a drawing object using a light beam.

  Conventionally, an image recording system for directly drawing a predetermined drawing pattern represented by digital data on a drawing object has been developed. As an image recording system, for example, a light beam modulated in accordance with a drawing pattern is applied to an exposed surface of an object to be drawn such as a printed wiring board or a glass panel for a flat panel display on which a photosensitive material is applied or adhered. There is known a digital exposure system that performs exposure recording without irradiating a mask.

  The digital exposure system is built into a large manufacturing system that integrates a series of processes from drawing pattern design and drawing object production to inspection of exposed drawing objects, packing, and shipping. It plays the role of pattern exposure. The drawing pattern is designed by, for example, CAD (Computer Aided Design), and vector data (or Gerber data) obtained by editing the drawing pattern designed by CAD by CAM (Computer Aided Manufacturing) is given to the digital exposure system. . In a digital exposure system, given vector data is rasterized by a raster image processor (RIP), and raster data generated thereby (whether exposure recording is performed for each pixel, “0” or “1”). Exposure recording is performed by driving and controlling a spatial light modulation element such as a DMD (Digital Micromirror Device (registered trademark)).

  In the digital exposure system, an important issue is how to accurately expose the drawing pattern at a normal position on the exposure surface of the drawing object due to the nature of the product to be handled. This is because if the exposure position of the drawing pattern is shifted, not only the performance of the product is remarkably deteriorated, but also the product may be defective and the yield may be deteriorated.

  However, the object to be drawn has some unevenness in the thickness direction due to the manufacturing conditions and the surrounding environment, such as thermal expansion when the press process is performed in the process before reaching the digital exposure system. For this reason, conventionally, the uneven shape of the exposure surface of the drawing object is measured, and the focus adjustment of the light beam is performed according to the measurement result. Specifically, an optical member such as a prism pair arranged at the light beam emission end is mechanically moved along the thickness direction of the drawing object.

  An object to be drawn is provided with an alignment mark for positioning when it is introduced into a digital exposure system and a land hole for mounting various electronic components. Conventional digital exposure systems distinguish between irregularities caused by manufacturing conditions and the surrounding environment from artificial formations such as alignment marks and land holes, and ignore the artificial formations to adjust the focus. (See Patent Document 1).

JP 2006-047958 A

  In mechanical focus adjustment using an optical member such as a prism pair, the range in which the optical member can be moved is limited, and thus the range in which focus adjustment is possible is naturally limited. Further, since exposure is performed on a drawing object that moves at a constant speed, the movement of the optical member may not be able to catch up with the movement of the drawing object, and there is a limit to the speed that can be followed by the movement of the optical member. Therefore, focus adjustment may not be performed when a part of the drawing object is warped and the uneven shape of the exposure surface is greatly changed or rapidly changed. In this case, there is no choice but to give up exposure to the object to be drawn, and the object to be drawn is discarded, resulting in a problem that the yield of the product is deteriorated.

  The present invention has been made in view of the above problems, and an object thereof is to provide an image recording method and an image recording system capable of improving the yield of products.

  In order to achieve the above object, an invention according to claim 1 is an image recording system for directly drawing a predetermined drawing pattern represented by digital data on a drawing object using a light beam. Based on the shape measurement means for measuring the uneven shape of the drawing surface of the drawing object to be formed, and the displacement data of the uneven shape by the shape measurement means, the light beam is focused on the drawing surface. A focus adjustment unit that mechanically adjusts the focus of the light beam and a correction unit that corrects the displacement data so as to enable the focus adjustment are provided.

  A difference calculating means for calculating a difference between the displacement data corrected by the correcting means and the original displacement data not corrected by the correcting means; a maximum value of the difference calculated by the difference calculating means and a threshold value; It is preferable that the image forming apparatus includes a drawing availability determination unit that determines whether or not the drawing is possible based on the comparison result.

  In this case, the drawing possibility determination unit determines that the drawing is possible when the maximum value of the difference is equal to or less than the threshold value, and does not allow the drawing when the maximum value of the difference is larger than the threshold value. It is determined that

The focus adjusting means is driven and controlled based on the displacement data corrected by the correcting means when the drawing possibility determining means determines that the drawing is possible.

It is preferable to provide operation input means for inputting the threshold value. The threshold value is preferably set according to at least the definition of the drawing pattern.

  It is preferable that the correction unit performs correction by performing a waveform blunting process that blunts the waveform of the uneven shape represented by the displacement data.

  The displacement data is analyzed, and is provided with a focus adjustment availability determination unit that determines whether or not the focus adjustment is possible, and the correction unit determines that the focus adjustment is impossible by the focus adjustment availability determination unit. Is preferably corrected.

  In this case, the correction means repeatedly corrects the displacement data until the focus adjustment availability determination means determines that the focus adjustment is possible.

  It is preferable that the focus adjusting unit includes a plurality of wedge-shaped optical members arranged at the light beam emission end. It is preferable that an exposure head having a spatial light modulator that modulates the light beam based on the digital data is provided.

  The invention according to claim 12 is an image recording method in which a predetermined drawing pattern represented by digital data is directly drawn on a drawing object using a light beam, and the drawing object on which the drawing pattern is formed is recorded. Based on the shape measuring step for measuring the uneven shape of the drawing surface and the displacement data of the uneven shape obtained in the shape measuring step, focus adjustment of the light beam so that the light beam is focused on the drawing surface And a correction step of correcting the displacement data so that the focus adjustment can be performed.

  According to the image recording method and the image recording system of the present invention, the displacement data of the uneven shape of the drawing surface of the drawing object on which the drawing pattern is formed is corrected so that the light beam can be focused. Therefore, drawing can be performed even when the drawing surface has irregularities that cannot be adjusted in focus. Therefore, the object to be drawn, which has conventionally been discarded because drawing is impossible, can be incorporated as a product without being discarded, and the yield of the product can be improved.

It is a perspective view which shows schematic structure of a digital exposure system. It is explanatory drawing which shows schematic structure of an exposure head. It is a perspective view which shows schematic structure of DMD. It is a figure for demonstrating the arrangement | positioning relationship between an exposure head and a shape measuring device. It is a block diagram which shows the internal structure of a digital exposure system. It is a block diagram which shows the internal structure of a control apparatus. It is a graph which shows the example of the measurement result of a shape measuring device. It is a graph which shows the process example of a waveform blunting process part. It is a graph which shows the example of a process of a difference calculation part. It is a flowchart which shows the operation | movement procedure of a digital exposure system. It is a flowchart which shows the procedure of the process performed by a control apparatus in response to the measurement result of a shape measuring device.

  In FIG. 1, the digital exposure system 2 includes a digital exposure machine 10, a light source unit 11, an image processing unit 12, and a control device 13. The digital exposure system 2 uses the image processing unit 12 to obtain vector data (or Gerber data) obtained by editing a predetermined drawing pattern (for example, a printed wiring pattern) designed by CAD (Computer Aided Design) using CAM (Computer Aided Manufacturing). Rasterization is performed on the basis of raster data generated by this (representing the presence / absence of exposure recording for each pixel in binary of “0” or “1”) using the digital exposure machine 10 and the light source unit 11. By exposing the drawing body 14, a desired image is formed on the drawing body 14 without a mask.

  The drawing object 14 is made of, for example, a printed wiring board in which a photosensitive material is applied or pasted to the exposure surface 14a, or a flat panel display glass substrate. An alignment mark 15 indicating the reference of the exposure position is provided on the exposure surface 14a. For example, the alignment marks 15 are formed by unevenness of a thin film, and a total of four alignment marks 15 are arranged at each of the four corners of the exposure surface 14a.

  The digital exposure machine 10 has a flat base 16. The base 16 is supported by the four legs 17 and is arranged in parallel to the horizontal plane. On the upper surface of the base 16, two guide rails 18 parallel to the Y direction (a direction parallel to the longitudinal direction of the base 16) are provided side by side. A moving stage 19 that sucks and holds the drawing target 14 is attached to the guide rail 18 so as to be slidable in the Y direction. The moving stage 19 is reciprocated in the Y direction by a stage driving unit 73 (see FIG. 5) including a driving source such as a linear motor. Although not shown, the moving stage 19 is provided with a mechanism for adjusting the position in the Z direction (direction orthogonal to the horizontal plane).

  An exposure unit 20 is disposed at the center of the base 16 in the Y direction. The exposure unit 20 is fixed to a gate-shaped first gate 21 erected so as to straddle the guide rail 18. The exposure unit 20 is provided with a total of eight cylindrical exposure heads 22 arranged in two rows of four in the X direction (a direction perpendicular to the Y direction on the horizontal plane).

  An optical fiber 23 drawn from the light source unit 11 and a signal cable 24 drawn from the image processing unit 12 are connected to the exposure head 22. The exposure head 22 is input from the light source unit 11 via the optical fiber 23 based on the frame data (the raster data divided for each exposure head 22) input from the image processing unit 12 via the signal cable 24. A laser beam (hereinafter abbreviated as LB) is modulated. Then, the modulated LB is irradiated to the drawing object 14 that passes directly under the movement of the moving stage 19 in the Y direction to perform exposure.

  The exposure heads 22 are arranged without a gap between the first row and the second row. The exposure heads 22 are arranged so as to be shifted by 1/2 pitch (radius) in the X direction between the first row and the second row (see also FIG. 4). Thereby, the part which cannot be exposed with the exposure head 22 of the 1st row | line | column is exposed with the exposure head 22 of the 2nd row | line, and the to-be-drawn body 14 can be exposed in the X direction without gap. Note that the number of exposure heads 22 and the way in which they are arranged can be appropriately changed according to the specifications of the drawing target 14.

  In FIG. 2, the exposure head 22 includes an incident optical system 30, a light modulator 31, a first emission optical system 32, a microlens array 33, an aperture array 34, and a second emission optical system 35. The incident optical system 30 is disposed so as to face the exit end of the optical fiber 23. The incident optical system 30 includes a condenser lens 36, an optical integrator 37, an imaging lens 38, and a mirror 39.

  The condensing lens 36 condenses the LB (indicated by an arrow) emitted from the optical fiber 23 toward the optical integrator 37. The optical integrator 37 is disposed on the optical path of the LB that has passed through the condenser lens 36, and is made of, for example, a rectangular column-shaped translucent rod in which an incident end face and an exit end face are coated with an antireflection film. The optical integrator 37 converts the LB that travels while totally reflecting the inside thereof into substantially parallel light with uniform intensity in the beam cross section. The LB converted into substantially parallel light by the optical integrator 37 is guided to the mirror 39 by the imaging lens 38 and is incident on the light modulator 31 by the mirror 39.

  The light modulation unit 31 includes a digital micromirror device (hereinafter abbreviated as DMD) 40 that is a spatial light modulation element, a DMD driver 41 that controls the operation of the DMD 40, and an LB incident through a mirror 39. And a total reflection prism 42 that reflects toward the DMD 40.

  In FIG. 3, the DMD 40 is configured such that a micromirror 61 is tiltably supported by a column on each SRAM cell constituting the SRAM cell array 60. For example, the micromirrors 61 are arranged in a 600 × 800 two-dimensional square lattice pattern.

  Frame data is written into each SRAM cell via the DMD driver 41. The SRAM cell is configured by a flip-flop circuit, and the charge state is switched depending on the frame data (“0” or “1”) to be written. The inclination angle of the micromirror 61 is changed by the electrostatic force according to the charge state of the SRAM cell, and the reflection direction of the LB also changes accordingly. For example, the micromirror 61 of the SRAM cell in which the frame data “0” is written is tilted so that LB enters the first emission optical system 32. On the other hand, when “1” is written, LB is inclined so as to enter a light absorber (not shown). LB incident on the light absorber is absorbed by the light absorber and does not contribute to exposure. Note that the DMD 40 has a short side slightly inclined with respect to the Y direction (for example, 0.1 ° to 0.00 mm) in order to increase the exposure resolution by narrowing the interval in the X direction of the scanning trajectory by each exposure head 22. 5 °) (see FIG. 4).

  Returning to FIG. 2, the first emission optical system 32 includes lenses 43 and 44, and LB from the light modulation unit 31 is enlarged to a predetermined magnification and is incident on the microlens array 33. The microlens array 33 is made of a light-transmitting material, for example, quartz glass, and a plurality of plano-convex lens-like microlenses 45 are integrally formed. The microlenses 45 have a one-to-one correspondence with the micromirrors 61 and are positioned on the optical axis of the incident LB. Due to the action of the micro lens 45, the incident LB is sharpened and incident on the aperture array 34.

  The aperture array 34 has a plurality of apertures 46 corresponding to the micromirrors 61 and arranged in a two-dimensional square lattice. The aperture array 34 is formed, for example, by depositing a light shielding film such as chromium on a quartz glass plate, and forming holes serving as the apertures 46 in the light shielding film. The LB incident from the microlens array 33 is focused at the position of the aperture 46 and guided to the second emission optical system 35. The aperture array 34 prevents unnecessary light from passing due to chattering of the micromirror 61 and further increases the sharpness of the LB.

  The second emission optical system 35 includes lenses 47 and 48 and a prism pair (corresponding to a plurality of wedge-shaped optical members) 49. The lenses 47 and 48 enlarge the LB from the aperture array 34 to a predetermined magnification, or enter the prism pair 49 with the same magnification. The prism pair 49 is provided so as to be movable in the Z direction by a focus control unit 74 (see FIG. 5) including a drive source such as a stepping motor. By moving in the Z direction, LB is focused on the exposure surface 14a. As described above, the focus adjustment of the LB is performed.

  Returning to FIG. 1, the light source unit 11 is provided with a plurality of GaN-based semiconductor lasers that emit LB having an oscillation wavelength in the range of 350 nm to 450 nm (for example, 405 nm). The GaN-based semiconductor laser has a maximum output of about 100 mW in the multimode and about 50 mW in the single mode. The LB emitted from each of the GaN-based semiconductor lasers is guided to the incident end of the optical fiber 23 as it is or after being multiplexed several times. Note that other types of semiconductor lasers or light emitting diodes (LEDs) may be used instead of the GaN-based semiconductor lasers.

  A gate-shaped second gate 25 is further erected on the base 16 so as to straddle the guide rail 18. A pair of length measuring devices 26 is attached to one end of the base 16 in the Y direction. The second gate 25 is provided with three cameras 27 that photograph from the upper side in the Z direction the subject to be drawn 14 that passes immediately below as the moving stage 19 moves in the Y direction. The camera 27 incorporates a solid-state imaging device such as a CCD image sensor, and outputs an imaging signal obtained by the solid-state imaging device to the position detection unit 75 (see FIG. 5).

  A shape measuring instrument 28 is attached to the other side surface of the second gate 25 provided with the camera 27. As the shape measuring instrument 28, for example, a laser interference type displacement meter is used that measures the uneven shape of the exposure surface 14a by irradiating the exposure surface 14a with laser light and receiving the reflected light. The resolution of the shape measuring instrument 28 is approximately 0.1 μm to 1 μm.

  As shown in FIG. 4, eight shape measuring instruments 28 are provided in the same number as the exposure head 22, and are arranged on a straight line passing through the center of the exposure head 22 and parallel to the Y direction. That is, the shape measuring instrument 28 measures the uneven shape of the exposure surface 14 a located at the center of the scanning range of the exposure head 22. The shape measuring instrument 28 is connected to the control device 13 (see FIG. 5), and outputs a measurement result to the control device 13. The laser beam emitted from the shape measuring instrument 28 is set to an oscillation wavelength that does not expose the drawing object 14.

  Similarly to the shape measuring instrument 28, the length measuring instrument 26 uses a laser displacement meter that irradiates the side end surface of the moving stage 19 with laser light and measures the position of the moving stage 19 in the Y direction. The length measuring device 26 is connected to the control device 13 (see FIG. 5), and outputs the length measurement result to the control device 13. In addition, as a shape measuring device and a length measuring device, you may use what consists of an ultrasonic transmitter / receiver and a stereo camera.

  In FIG. 5, the control device 13 comprehensively controls the overall operation of the digital exposure system 2. The control device 13 stores in advance a program and data for performing the above-described control in a storage unit (not shown) such as an HDD or a ROM. The control device 13 reads out necessary programs and data from the storage unit, develops them in a working memory such as a RAM, and sequentially processes the read programs.

  In addition to the light source unit 11 described above, the control device 13 includes a memory 70 of the image processing unit 12, a raster image processor (hereinafter abbreviated as RIP) 71, a frame data generation unit 72, and a digital exposure machine. Ten DMD drivers 41, a stage drive unit 73, a focus control unit 74, a position detection unit 75, a length measuring device 26, and a shape measuring device 28 are connected.

  The memory 70 temporarily stores vector data transmitted from an external device such as a CAM. The RIP 71 reads vector data from the memory 70 and rasterizes the vector data to generate raster data. The RIP 71 outputs the generated raster data to the frame data generation unit 72.

  The frame data generation unit 72 divides raster data from the RIP 71 for each exposure head 22 based on the exposure position of each exposure head 22 on the drawing target 14 determined by the arrangement of the micromirror 61 and the exposure head 22. Is generated. Further, the frame data generation unit 72 performs exposure at the same position as when no shift occurs according to the shift amount of the drawing object 14 with respect to the reference position on the moving stage 19 detected by the position detection unit 75. As described above, the frame data is corrected. The frame data generation unit 72 outputs the generated frame data to the DMD driver 41 of the corresponding exposure head 22. As described above, the DMD driver 41 writes the frame data from the frame data generation unit 72 to the SRAM cell.

  The position detection unit 75 converts the image pickup signal from the camera 27 into digital image data by known signal processing. Based on the converted image data, the position of the camera 27 in the X direction, and its shooting timing (both the position and the shooting timing are known), the position detection unit 75 positions the alignment mark 15 of the drawing object 14 on the moving stage 19. Is detected. The position detection unit 75 outputs the position detection result to the control device 13.

  The control device 13 receives the detection result from the position detection unit 75, and the X direction, the Y direction, and the θ direction of the drawing target 14 with respect to the reference position on the moving stage 19 (the rotation direction about the Z direction, 1) is calculated. The control device 13 calculates a correction amount of the frame data from the calculated shift amount, and outputs this information to the frame data generation unit 72. Further, the control device 13 receives the output from the length measuring device 26 and detects the position of the moving stage 19 in the Y direction.

  In FIG. 6, the control device 13 is provided with a focus adjustment availability determination unit 80. The focus adjustment availability determination unit 80 analyzes the output from the shape measuring instrument 28, that is, waveform data representing the uneven shape of the exposure surface 14a (hereinafter referred to as displacement data), and the uneven shape of the exposure surface 14a is converted into a prism. It is determined whether or not the focus adjustment by the pair 49 is possible.

  Here, the focus adjustment by the prism pair 49 is a mechanical adjustment performed by moving the prism pair 49 in the Z direction. Therefore, the range in which the focus adjustment is possible is naturally limited, and can follow the movement of the drawing object 14. There is a limit to the speed. Therefore, there is a case where the focus adjustment cannot be performed when a part of the drawing object 14 is warped and the uneven shape of the exposure surface 14a is greatly changed or rapidly changed.

  Therefore, the focus adjustment availability determination unit 80 obtains the unevenness change amount (for example, the difference between the maximum value and the minimum value or the difference between the average values) and the inclination thereof from the displacement data. Then, whether or not the focus adjustment is possible is determined by determining whether or not the obtained change amount and inclination are within the range in which the focus adjustment of the prism pair 49 can be performed and the speed in which the prism pair 49 can follow.

  The waveform blunting processing unit 81 performs an appropriate filtering process on the displacement data determined to be incapable of focus adjustment by the focus adjustment availability determination unit 80, and obtains a portion of the waveform that is greatly or rapidly changing. Blunt. The waveform blunting processing unit 81 feeds back the processed displacement data again to the focus adjustment availability determination unit 80 and repeats the waveform blunting processing until it is determined by the focus adjustment availability determination unit 80 that focus adjustment is possible. An example of the filtering process is a moving average widely used as a process for smoothing data. When the waveform blunting process is repeatedly performed, the range (mask size) to which the moving average is applied is gradually expanded, and the waveform is blunted little by little. Needless to say, the waveform blunting processing unit 81 naturally performs the waveform blunting processing on the displacement data determined to be focus adjustable in the first determination by the focus adjustment availability determination unit 80. Do not give. The displacement data determined to be focus adjustable in the first determination is output to the focus control signal generator 84 as it is.

  The difference calculation unit 82 determines that the focus adjustment is impossible by the focus adjustment availability determination unit 80, and displacement data (hereinafter referred to as original data) input from the focus adjustment availability determination unit 80 without passing through the waveform blunting processing unit 81. ) And the displacement data (hereinafter referred to as processed data) subjected to the waveform blunting processing by the waveform blunting processing unit 81 until it is determined that the focus adjustment is possible by the focus adjustment possibility determining unit 80. The calculation result is output to the exposure possibility determination unit 83.

  The exposure possibility determination unit 83 compares the maximum value of the difference between the original data from the difference calculation unit 82 and the processed data with a threshold value. The exposure possibility determination unit 83 determines that exposure is possible when the maximum value of the difference between the original data and the processed data is equal to or less than a threshold value. Conversely, when the maximum value is larger than the threshold value, it is determined that exposure is impossible. The exposure propriety determination unit 83 outputs an exposure propriety determination result to the focus control signal generation unit 84.

  The maximum difference between the original data and the processed data is how much the uneven shape (processed data) corrected by the waveform blunting process deviates from the actual uneven shape (original data) of the exposure surface 14a. It shows the degree. Further, the threshold value used as a reference for determining whether exposure is possible is determined by the definition of the drawing pattern and the required accuracy of exposure recording, and is input by the operator operating the operation unit 85 such as a keyboard or a mouse. The When focus control is performed based on processed data, the threshold value is set to a limit value that satisfies the required precision of the drawing pattern definition and exposure recording (the allowable range of the degree of deviation from the actual uneven shape). The Therefore, when the definition of the drawing pattern and the required accuracy of exposure recording are high (low), the threshold is set low (high), and the range that is determined to be possible by the exposure determination unit 83 is narrowed (expanded). It is done.

  The focus control signal generation unit 84 generates a focus control signal for controlling the movement of the prism pair 49 in the Z direction so that the LB is focused on the exposure surface 14 a by the focus adjustment by the prism pair 49. When it is determined by the first determination by the focus adjustment availability determination unit 80 that the focus adjustment is possible, the focus control signal generation unit 84 receives the displacement inputted as it is without passing through the waveform blunting processing unit 81 or the like. A focus control signal corresponding to the data is generated.

  On the other hand, it is determined that the focus adjustment is not possible by the focus adjustment availability determination unit 80, and there is displacement data that has been determined that the focus adjustment is possible via the waveform blunting processing unit 81, that is, processed data exists, and the processing When it is determined that exposure is possible with respect to the completed data, the focus control signal generation unit 84 generates a focus control signal corresponding to the processed data. When the exposure determination unit 83 determines that exposure is not possible, the focus control signal generation unit 84 does not generate a focus control signal, and therefore exposure recording itself is not performed. Here, only one unit such as the focus adjustment availability determination unit 80 is depicted, but in practice, the number of exposure heads 22 and the number of shape measuring instruments 28 (eight) are provided. Of course, each of the eight exposure heads 22 and the shape measuring instrument 28 may be provided one by one, and eight processes may be performed by one processing unit.

  Hereinafter, the operation of each unit will be described with specific examples. First, it is assumed that the corrugated waveform of the exposure surface 14a by the eight shape measuring instruments 28 is as shown in FIG. That is, one end of the drawing object 14 is floating above the moving stage 19, and the displacement in the Z direction of one waveform A indicated by a thick line is large and suddenly changes at the end of the Y direction position (portion surrounded by a dotted line). Consider the case where you were. Then, it is assumed that only the displacement data representing the waveform A is determined by the focus adjustment availability determination unit 80 to be unable to adjust the focus.

  The displacement data representing the waveform A is subjected to waveform blunting processing by the waveform blunting processing unit 81 until it is determined by the focus adjustment availability determining unit 80 that focus adjustment is possible, and the waveform A ′ indicated by the dotted line in FIG. Thus, the part surrounded by the dotted line which is large and changes rapidly is blunted.

  Next, as shown in FIG. 9, the difference calculation unit 82 calculates the displacement data represented by the waveforms A and A ′, that is, the difference Δ between the original data and the processed data. The difference Δ is calculated at regular intervals with respect to the position in the Y direction, for example.

  Then, the exposure propriety determination unit 83 compares the maximum difference Δmax with the threshold value to determine whether exposure is possible. If it is determined that exposure is possible, a focus control signal is generated based on the processed data represented by the waveform A ′. If it is determined that exposure is impossible, exposure recording is not performed.

  On the other hand, the displacement data representing a waveform other than the waveform A (indicated by a thin line in FIG. 7) that has been determined that the focus adjustment is possible by the focus adjustment availability determination unit 80 and has not passed through the waveform blunting processing unit 81 is directly focused. The signal is output to the signal generator 84, and a focus control signal is generated based on this.

  Next, the operation procedure of the digital exposure system 2 configured as described above will be described with reference to the flowcharts of FIGS. First, in S10, prior to exposure recording, vector data is transmitted from an external device such as a CAM to the memory 70, and the vector data is stored in the memory 70.

  The vector data stored in the memory 70 is read out to the RIP 71. In S11, the RIP 71 rasterizes the vector data to generate raster data.

  After the raster data is generated, when exposure recording on the drawing object 14 is instructed, the drawing object 14 is set on the moving stage 19 located at the position shown in FIG. 1 in S12. In S13, the stage drive unit 73 is driven by the control device 13, and the moving stage 19 is moved toward the second gate 25 at a constant speed in the Y direction.

  The moving stage 19 is moved in the Y direction and passes directly under the second gate 25. At this time, the drawing object 14 on the moving stage 19 is photographed by the camera 27 in S14. An imaging signal obtained by the camera 27 is output to the position detection unit 75. Further, the shape measuring device 28 measures the uneven shape of the exposure surface 14a. The measurement result of the shape measuring instrument 28 is output to the control device 13.

  In FIG. 11, the control device 13 receives the measurement result of the shape measuring instrument 28, and as shown in S <b> 30, the displacement data is analyzed by the focus adjustment availability determination unit 80 to determine whether focus adjustment is possible. When it is determined that the focus adjustment is possible in the first determination (both yes in S31 and 32), the focus control signal generator 84 generates a focus control signal corresponding to the displacement data, as shown in S33. Generated.

  When it is determined that the focus adjustment is impossible (no in S31), the displacement data is output to the waveform blunting processing unit 81, and the waveform blunting processing unit 81 performs the waveform blunting processing in S34. The displacement data subjected to the waveform blunting process is fed back to the focus adjustment availability determination unit 80, and the focus adjustment availability determination unit 80 determines again whether the focus adjustment is possible (return to S30).

  When the waveform blunting processing unit 81 performs the waveform blunting processing and it is determined that the focus adjustment is possible by the determination again (yes in S31, no in S32), as shown in S35, the difference calculation unit 82 and the original data The difference from the processed data is calculated. The calculation result of the difference calculation unit 82 is output to the exposure possibility determination unit 83.

  In S 36, the exposure possibility determination unit 83 compares the maximum value of the difference between the original data and the processed data from the difference calculation unit 82 and the threshold value input from the operation unit 85. If the maximum difference between the original data and the processed data is equal to or less than the threshold value, it is determined that exposure is possible (yes in S37). Conversely, when the maximum value is larger than the threshold value, it is determined that exposure is impossible (no in S37). The determination result of the exposure possibility determination unit 83 is output to the focus control signal generation unit 84.

  When it is determined that exposure is possible, the focus control signal generation unit 84 generates a focus control signal corresponding to the processed data, as shown in S38. It should be noted that S38 and S33 are the same as the processing items, but note that the types of displacement data from which the focus control signal is generated are different. After the focus control signal is generated, the process proceeds to S18 in FIG. On the other hand, if the exposure determination unit 83 determines that exposure is not possible, the focus control signal is not generated, and the process proceeds to S20 in FIG.

  Returning to FIG. 10, in S15, in the position detection unit 75, the imaging signal input from the camera 27 in S14 is converted into digital image data, and the image data, the position of the camera 27 in the X direction, and the shooting timing thereof. Based on the above, the position of the alignment mark 15 of the drawing object 14 on the moving stage 19 is detected. The detection result of the position detector 75 is output to the control device 13.

  In the control device 13, the detection result of the alignment mark 15 from the position detection unit 75 is analyzed, and deviation amounts in the X direction, the Y direction, and the θ direction of the drawing target 14 with respect to the reference position on the moving stage 19 are calculated. The Next, as shown in S16, the correction amount of the frame data is calculated from the calculated shift amount. The calculated correction amount of the frame data is output to the frame data generation unit 72.

  Next, as shown in S <b> 17, the frame data generation unit 72 generates frame data corresponding to each exposure head 22. At this time, the frame data is corrected in accordance with the correction amount from the control device 13 so that the exposure is performed at the same position as when no deviation has occurred. The generated frame data is output to the DMD driver 41 of the corresponding exposure head 22. When the generation of the frame data and the generation of the focus control signal in S33 or S38 of FIG. 11 are finished, the moving stage 19 moves at the same speed toward the original position, as shown in S18, as opposed to the initial direction. In S19, the light source unit 11 is driven by the control device 13, and exposure recording by the exposure unit 20 is started.

  The frame data output to the DMD driver 41 is sequentially written into the SRAM cell according to the position in the Y direction of the moving stage 19 measured by the length measuring device 26. As a result, the charge state of the SRAM cell is switched depending on the frame data to be written, and the inclination angle of the micromirror 61 is changed, so that the reflection direction of LB from the light source unit 11 given through the optical fiber 23 and the incident optical system 30 is also changed. Changed. That is, the LB from the light source unit 11 is optically modulated according to the frame data by the optical modulation unit 31 configured by the DMD 40 or the like.

  The LB modulated by the light modulator 31 is enlarged to a predetermined magnification by the first emission optical system 32, sharpened by the microlens 45, and incident on the aperture array 34. Then, the aperture array 34 further sharpens and prevents unnecessary light from passing due to chattering of the micromirror 61.

  The LB that has passed through the aperture array 34 is magnified to a predetermined magnification by the second emission optical system 35 or is incident on the prism pair 49 with the same magnification, and the prism pair 49 performs focus adjustment. At this time, the movement of the prism pair 49 in the Z direction is controlled by the focus control unit 74 based on the focus control signal generated in S33 or S38. The LB whose focus has been adjusted by the prism pair 49 is irradiated onto the drawing object 14 on the moving stage 19, whereby a desired image is exposed and recorded on the drawing object 14.

  After the exposure recording on one drawing object 14 is completed, or when it is determined that the exposure is impossible by the exposure determination unit 83 and there is a next drawing object 14 (Yes in S20), as shown in S21, The drawing object 14 for which exposure recording has been completed or that has been determined to be non-exposure is collected from the moving stage 19, and the process returns to S 12 to set the next drawing object 14 on the moving stage 19. The process is repeated.

  On the other hand, when there is no next drawing object 14 (no in S20) and replacement of vector data is instructed (yes in S22), a drawing object 14 that matches the exchanged vector data is prepared, and in S10 Returning, the following steps such as rasterization are repeated. If the replacement of vector data is not instructed (no in S22), the process ends.

  As described above, when the uneven shape of the exposure surface 14a is determined to be impossible to adjust the focus, the waveform is blunted so that the focus can be adjusted. Even if the image is slightly out of specification, exposure recording can be performed. That is, the allowable range of the quality of the drawing object 14 is expanded. In other words, it is not necessary to strictly manage the manufacturing conditions of the drawing object 14 and the surrounding environment in order to eliminate a large or abrupt change in the uneven shape of the exposure surface 14a. That is, stable control is maintained regardless of uncertain factors that are difficult to identify, such as disturbances due to manufacturing conditions of the drawing object 14 and the surrounding environment, design errors, and the like (to improve the robustness of the digital exposure system 2). Can do.

  Since the difference between the original data and the processed data is calculated and the final exposure recording is determined from the comparison result between the maximum value and the threshold value, the required minimum quality can be ensured.

  In the above-described embodiment, the waveform blunting processing unit 81 performs the waveform blunting process on the displacement data that has been determined that the focus adjustment is impossible after the focus adjustment propriety determination unit 80 determines whether the focus adjustment is possible. However, it may be determined whether or not the focus adjustment is possible after the waveform blunting process is first performed unconditionally on all the displacement data. Further, a limit may be set for the number of repetitions of the waveform blunting process, and it may be determined that the exposure is impossible when it is determined that the focus adjustment is impossible even if the waveform blunting process is repeated several times.

  In the above embodiment, an example in which the threshold value is input from the operation unit 85 has been described. However, the threshold value may be set at least according to the definition of the drawing pattern, and the threshold value for the definition of the drawing pattern is set in advance by the control device 13. It is good also as a structure which memorize | stores in this memory | storage part and reads this to the exposure availability determination part 83. FIG. Further, a threshold value may be set according to the resolution of the raster data. Alternatively, a threshold value may be set by referring to this data by measuring how much the line width of the drawing pattern is shifted when the focus is shifted. In short, it is only necessary that the threshold is set to a value that can ensure the minimum quality.

  If the exposure determination unit 83 determines that exposure is not possible, the operator may be notified by displaying such information on a monitor or by sounding a warning sound from a speaker. In this case, the operator may be able to know which part of the exposure surface 14a is deformed by displaying a waveform by the shape measuring instrument 28.

  Another method for improving the product yield is to analyze the displacement data and create a histogram showing the frequency of appearance of the amount of displacement in the Z direction on the exposure surface 14a, and match the LB with the most frequent amount of displacement. There is a method of generating a focus control signal so as to focus. Alternatively, it is conceivable that the depth of field of various optical systems constituting the exposure head 22 is increased so that the focus adjustment itself is unnecessary. Further, the exposure surface 14a may be corrected so as to be flat enough to enable focus adjustment by increasing the suction force of the moving stage 19 to the drawing target 14, for example.

  In the above embodiment, the DMD 40 is shown as the spatial light modulation element. However, the spatial light modulation element is not limited to this, and for example, an SLM (Special Light Modulator), a liquid crystal optical shutter, and a PLZT (Piezo-electric Lanthanum). -modified lead Zirconate Titanate) element may be used. Further, in the above-described embodiment, the drawing object 14 on which a photosensitive material is applied or stuck as an exposure target is shown. However, for example, a photographic film or photographic paper may be used. Furthermore, in the above-described embodiment, an example in which the present invention is applied to the digital exposure system 2 has been described.

DESCRIPTION OF SYMBOLS 2 Digital exposure system 10 Digital exposure machine 11 Light source unit 12 Image processing unit 13 Control apparatus 14 Drawing object 14a Exposure surface 20 Exposure part 22 Exposure head 28 Shape measuring device 40 DMD
49 Prism Pair 74 Focus Control Unit 80 Focus Adjustability Determining Unit 81 Waveform Blur Processing Unit 82 Difference Calculation Unit 83 Exposure Allowability Determining Unit 85 Operation Unit

Claims (5)

In an image recording system for directly drawing a predetermined drawing pattern represented by digital data on a drawing object using a light beam,
A shape measuring means for measuring an uneven shape of a drawing surface of the drawing object on which the drawing pattern is formed;
A focus adjusting unit that mechanically adjusts the focus of the light beam so that the light beam is focused on the drawing surface based on the displacement data of the uneven shape by the shape measuring unit;
Correction means for correcting the displacement data so that the focus adjustment is possible;
A focus adjustment availability determination unit that analyzes the displacement data and determines whether the focus adjustment is possible;
The correction means, until it is determined by the focus adjustment availability determination means that the focus adjustment is possible, with respect to the displacement data determined that the focus adjustment is impossible by the focus adjustment availability determination means. An image recording system characterized by repeatedly performing correction.   The image recording system according to claim 1, wherein the correction unit performs correction by performing a waveform blunting process that blunts the waveform of the uneven shape represented by the displacement data. 3. The image recording system according to claim 1, wherein the focus adjustment unit includes a plurality of wedge-shaped optical members disposed at an emission end of the light beam. The image recording system according to any one of claims 1 to 3, characterized in that it comprises an exposure head having a spatial light modulator for modulating the light beam on the basis of the digital data. In an image recording method for directly drawing a predetermined drawing pattern represented by digital data on a drawing object using a light beam,
A shape measuring step of measuring the uneven shape of the drawing surface of the drawing object on which the drawing pattern is formed;
A focus adjustment step of mechanically adjusting the focus of the light beam based on the displacement data of the concavo-convex shape obtained in the shape measurement step, so that the light beam is focused on the drawing surface;
A correction step of correcting the displacement data so as to enable the focus adjustment;
A focus adjustment availability determination step of analyzing the displacement data and determining whether the focus adjustment is possible,
In the correction step, until it is determined that the focus adjustment is possible in the focus adjustment availability determination step, with respect to the displacement data determined that the focus adjustment is impossible in the focus adjustment availability determination step, An image recording method comprising repeatedly performing correction.

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