JP2005294373A - Multi-beam exposing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control an exposing head through adjustment to draw a pattern with higher accuracy on a recording surface in scanning and exposing with a multi-beam emitted from a means for selectively turning ON/OFF a plurality of pixels. <P>SOLUTION: The multi-beam exposing apparatus 10 is provided with a two-dimensional light detecting means 100 for simultaneously measuring, on the recording surface, position, shape, and amount of light of each optical beam irradiated from the means for selectively turning ON/OFF a plurality of pixels. Accordingly, at the time of exposing process with the beam emitted from the side of the means for selectively turning ON/OFF a plurality of pixels, a high quality exposed image can be obtained through high precision exposing process by adequately controlling the drive of the means for selectively turning ON/OFF a plurality of pixels, on the basis of the data about position of light beam, shape and amount of light of the light beam obtained with measurement on the recording surface with the two-dimensional light detecting means 100. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to the position, shape, and position of each multi-beam emitted from a means for selectively turning on / off a plurality of pixels such as a spatial light modulation element installed in an exposure head based on image data (pattern data). The present invention relates to a multi-beam exposure apparatus configured to be able to measure light quantity data.

  In recent years, a multi-beam exposure apparatus that uses a spatial light modulation element such as a digital micromirror device (DMD) as a pattern generator to perform image exposure on a member to be exposed by a light beam modulated according to image data. Development is underway.

  This DMD is a mirror device in which a large number of micromirrors whose reflecting surfaces change in response to a control signal, for example, are two-dimensionally arranged on a semiconductor substrate such as silicon, and the electrostatic force generated by charges stored in each memory cell. Thus, the angle of the reflection surface of the micromirror is changed.

  In a conventional multi-beam exposure apparatus using a DMD, for example, a laser beam emitted from a light source that emits a laser beam is collimated by a lens system, and a plurality of DMD micromirrors arranged at a substantially focal position of the lens system. An exposure head that reflects each laser beam and emits each beam from a plurality of beam exits is used.

  This multi-beam exposure apparatus uses a lens system having an optical element such as a microlens array for condensing each beam emitted from a beam emission port of an exposure head with one lens for each pixel (pixel). There has been proposed one that forms an image with a reduced spot diameter on the exposure surface of a member to be exposed and performs image exposure with high resolution (for example, see Patent Document 1).

  In such a multi-beam exposure apparatus, each of the DMD micromirrors is controlled on / off by a control device (not shown) based on a control signal generated according to image data or the like to modulate (deflect) the laser beam. Then, exposure is performed by irradiating the exposure surface (recording surface) with the modulated laser beam.

  In this multi-beam exposure apparatus, a photosensitive material (photoresist, etc.) is arranged on the recording surface, and a laser beam is irradiated onto each photosensitive material from a plurality of exposure heads so that the positions of the imaged beam spots are relative to the photosensitive material. Thus, each DMD is modulated in accordance with image data while being relatively moved, so that processing for exposing a high-definition pattern on the photosensitive material in a short time can be executed.

  In order to perform high-precision exposure processing with such a multi-beam exposure apparatus, the position, shape and light quantity data of each light beam projected from the exposure head is accurately measured on the recording surface, and the measurement result Based on the above, it is necessary to adjust and control the exposure head so that proper drawing is performed on the photosensitive material.

However, there is no conventional multi-beam exposure apparatus that can simultaneously measure the position, shape and light quantity data of each light beam on the recording surface.
Special table 2002-520840

  In view of the above-described circumstances, the present invention provides an image on a recording surface when scanning exposure with a multi-beam emitted from means for selectively turning on / off a plurality of pixels such as a spatial light modulation element installed in an exposure head. A multi-beam exposure apparatus equipped with means capable of simultaneously detecting the position, shape and light quantity data of each light beam on the recording surface in order to adjust and control the exposure head so as to perform accurate and appropriate drawing. The purpose is to provide a new one.

  A multi-beam exposure apparatus according to claim 1 of the present invention is a multi-beam exposure apparatus having an exposure head having means for selectively turning on / off a plurality of pixels, and selectively turning on / off the plurality of pixels. And a two-dimensional light detecting means for simultaneously measuring the position, shape and light quantity of each light beam emitted from the means for carrying out on the recording surface.

  By configuring as described above, when performing exposure processing with a beam emitted from the means side for selectively turning on / off a plurality of pixels of the exposure head, measurement is performed on the recording surface by a two-dimensional light detection means. By appropriately driving and controlling the means for selectively turning on / off a plurality of pixels based on the data relating to the position of the light beam, the shape of the light beam, and the amount of light obtained, high-precision exposure processing can be performed. So that a high-quality exposure image can be obtained.

  According to a second aspect of the present invention, in the multi-beam exposure apparatus according to the first aspect, a plurality of microlenses corresponding one-to-one to each pixel of the means for selectively turning on / off the plurality of pixels are integrated. When a predetermined pixel is turned on by means for selectively turning on / off a plurality of pixels and a plurality of light beams are detected by a two-dimensional light detection means Detecting the position and light quantity of each light beam to discriminate between an ON light beam by a lit pixel and a child light beam by stray light, and a means for selectively turning on / off a plurality of pixels and a microlens array And a means for selectively turning on / off a plurality of pixels so as to eliminate stray light by driving and controlling the position adjusting means based on the positional relation. And adjusting the relative positions of the b.

  With the configuration described above, in addition to the operation and effect of the invention of the first aspect, stray light can be reduced, and high-quality exposure images can be obtained by drawing with higher accuracy.

  A multi-beam exposure apparatus according to a third aspect of the present invention includes a light source unit that emits laser light, and spatially modulates the laser light emitted from the light source unit based on desired image data, and the modulated laser light. A spatial light modulation element for irradiating the photosensitive material on the recording surface as an exposure beam, and a two-dimensional light detection means for measuring a light amount distribution on the recording surface irradiated from the spatial light modulation element, When the light amount distribution on the recording surface detected by the two-dimensional light detection means is uneven, the light intensity distribution on the spatial light modulator is adjusted to make the light amount distribution on the recording surface uniform. And a light amount distribution adjusting means.

  With the configuration described above, the light quantity distribution on the recording surface is detected by the two-dimensional light detection means, and if the light quantity distribution is uneven at this time, the light quantity distribution adjustment means The relative position of the optical path to the spatial light modulation element is moved to adjust the spatial distribution of the light incident on the spatial light modulation element, and the light quantity distribution on the recording surface is made uniform, so high-precision exposure Processing can be performed to obtain a high-quality exposure image.

  According to the multi-beam exposure apparatus according to the present invention, each of the plurality of pixels such as a spatial light modulation element installed in the exposure head is subjected to scanning exposure with a multi-beam emitted from a unit that selectively turns on / off. By appropriately adjusting and controlling the exposure head based on the data simultaneously detected on the recording surface, the position, shape, and light quantity of the light beam, high-quality exposure images can be obtained by performing high-precision drawing. There is an effect.

Embodiments relating to the multi-beam exposure apparatus of the present invention will be described with reference to FIGS.
[Configuration of Image Forming Apparatus]
As shown in FIG. 1, an image forming apparatus 10 configured as a multi-beam exposure apparatus according to an embodiment of the present invention is configured as a so-called flat bed type, and is supported by four leg members 12A. A base 12 and a surface of a glass substrate such as a printed circuit board (PCB), a color liquid crystal display (LCD), or a plasma display panel (PDP) that moves in the Y direction in the figure provided on the base 12 A moving stage 14 on which a photosensitive material 11 such as a photosensitive material formed thereon is fixed and moved; and a light source unit 16 that emits a multi-beam including a UV wavelength region extending in one direction as a laser beam; This multi-beam is spatially modulated according to the position of the multi-beam based on the desired image data, and the photosensitive material has sensitivity in the multi-beam wavelength region The exposure head unit 18 irradiates the modulated multi-beam as an exposure beam, and the control unit 20 generates a modulation signal to be supplied to the exposure head unit 18 from the image data as the moving stage 14 moves. Configured.

  In the image forming apparatus 10, an exposure head unit 18 for exposing a photosensitive material is disposed above the moving stage 14. The exposure head unit 18 is provided with a plurality of exposure heads 26. Each exposure head 26 is connected with a bundled optical fiber 28 drawn from the light source unit 16.

  The image forming apparatus 10 is provided with a portal frame 22 so as to straddle the base 12, and a pair of position detection sensors 24 are attached to both sides thereof. The position detection sensor 24 supplies a detection signal when the passage of the moving stage 14 is detected to the control unit 20.

  In this image forming apparatus 10, two guides 30 extending along the stage moving direction are installed on the upper surface of the base 12. The moving stage 14 is mounted on the two guides 30 so as to be able to reciprocate. The moving stage 14 is configured to be moved by a linear motor (not shown) at a relatively low constant speed such as a moving amount of 1000 mm, for example, 40 mm / second.

  In the image forming apparatus 10, scanning exposure is performed while moving the photosensitive material (substrate) placed on the moving stage 14 with respect to the fixed exposure head unit 18.

  As shown in FIG. 2, a plurality of (for example, eight) exposure heads 26 arranged in a substantially matrix of m rows and n columns (for example, 2 rows and 4 columns) are installed inside the exposure head unit 18.

  The exposure area 32 by the exposure head 26 is configured in a rectangular shape having a short side in the scanning direction, for example. In this case, a strip-shaped exposed region 34 is formed for each exposure head 26 in the photosensitive material 11 along with the scanning exposure moving operation.

  Further, as shown in FIG. 2, each of the exposure heads 26 in each row arranged in a line is arranged at a predetermined interval (in the arrangement direction) so that the strip-shaped exposed regions 34 are arranged without gaps in the direction orthogonal to the scanning direction. The exposure area is shifted by a natural number times the long side). For this reason, for example, a portion that cannot be exposed between the exposure area 32 of the first row and the exposure area 32 of the second row can be exposed by the exposure area 32 of the second row.

  As shown in FIG. 3, each exposure head 26 includes a digital micromirror device (DMD) 36 as a spatial light modulation element that modulates an incident light beam for each pixel according to image data. Yes. The DMD 36 is connected to a control unit (control means) 20 having data processing means and mirror drive control means.

  The data processing unit of the control unit 20 generates a control signal for driving and controlling each micromirror in the region to be controlled by the DMD 36 for each exposure head 26 based on the input image data. Further, the mirror drive control means as the DMD controller controls the angle of the reflection surface of each micromirror in the DMD 36 for each exposure head 26 based on the control signal generated by the image data processing unit.

  As shown in FIG. 1, each exposure head 26 is led out from a light source unit 16, which is an illumination device that emits a multi-beam extending in one direction including an ultraviolet wavelength region as laser light. The bundled optical fiber 28 is connected.

  Although not shown, the light source unit 16 is provided with a plurality of multiplexing modules that combine laser beams emitted from a plurality of semiconductor laser chips and input them to the optical fiber. The optical fiber extending from each multiplexing module is a multiplexing optical fiber that propagates the combined laser beam, and a plurality of optical fibers are bundled into one to form a bundle-like optical fiber 28.

  As shown in FIG. 4, the DMD 36 is configured such that a micromirror (micromirror) 46 is supported on a SRAM cell (memory cell) 44 by a support column, and a large number of (pixels) (pixels) are formed. For example, it is configured as a mirror device in which 600 × 800) micromirrors are arranged in a lattice pattern. Each pixel is provided with a micromirror 46 supported by a support column at the top, and a material having high reflectance such as aluminum is deposited on the surface of the micromirror 46.

  Directly below each micromirror 46 is disposed a silicon gate CMOS SRAM cell 44 manufactured on a normal semiconductor memory manufacturing line via a post including a hinge and a yoke (not shown), and the whole is monolithic. (Integrated type).

  When a digital signal is written to the SRAM cell 44 of the DMD 36, the micromirror 46 supported by the support is tilted in a range of ± a degrees (for example, ± 10 degrees) with respect to the substrate side on which the DMD 36 is disposed with the diagonal line as the center. It is done. FIG. 5A shows a state in which the micromirror 46 is tilted to + a degrees in the on state, and FIG. 5B shows a state in which the micromirror 46 is tilted to −a degrees in the off state. Therefore, by controlling the inclination of the micromirror 46 in each pixel of the DMD 36 as shown in FIG. 4 in accordance with the image signal, the light incident on the DMD 36 is reflected in the inclination direction of each micromirror 46. .

  FIG. 4 shows an example of a state in which a part of the DMD 36 is enlarged and the micromirror 46 is controlled to + a degree or −a degree. The on / off control of each micromirror 46 is performed by the control unit 20 connected to the DMD 36, and the light reflected by the on-state micromirror 46 is modulated into an exposure state, and the light of the DMD 36 The light enters the projection optical system (see FIG. 3) provided on the exit side. The light reflected by the micromirror 46 in the off state is modulated into a non-exposure state and is incident on a light absorber (not shown).

  Further, it is preferable that the DMD 36 is disposed slightly inclined so that the short side direction forms a predetermined angle (for example, 0.1 ° to 0.5 °) with the scanning direction. 6A shows the scanning trajectory of the reflected light image (exposure beam) 48 by each micromirror when the DMD 36 is not tilted, and FIG. 6B shows the scanning trajectory of the exposure beam 48 when the DMD 36 is tilted. Show.

In the DMD 36, a number of micromirror arrays in which a large number (for example, 800) of micromirrors 46 are arranged along the longitudinal direction (row direction) are arranged in a short direction (for example, 600 sets). 6B, by tilting the DMD 36, the pitch P ₂ of the scanning trajectory (scanning line) of the exposure beam 48 by each micromirror 46 becomes the pitch P of the scanning line when the DMD 36 is not tilted. Narrower than _{1 and} can greatly improve the resolution. On the other hand, since the tilt angle of the DMD 36 is very small, the scan width W ₂ when the DMD 36 is tilted and the scan width W ₁ when the DMD 36 is not tilted are substantially the same.

  Further, substantially the same position (dot) on the same scanning line is overlapped and exposed (multiple exposure) by different micromirror rows. In this way, by performing multiple exposure, it is possible to control a minute amount of the exposure position and to realize high-definition exposure. Further, the joints between the plurality of exposure heads arranged in the scanning direction can be connected without any step by controlling a very small amount of exposure position.

  Note that the same effect can be obtained by arranging the micromirror rows in a staggered manner at a predetermined interval in the direction orthogonal to the scanning direction instead of inclining the DMD 36.

  Next, a projection optical system (imaging optical system) provided on the light reflection side of the DMD 36 in the exposure head 26 will be described. As shown in FIG. 3, the projection optical system provided on the light reflection side of the DMD 36 in each exposure head 26 projects the light source image onto the photosensitive material 11 on the exposure surface on the light reflection side of the DMD 36, so The optical members for exposure of the lens systems 50 and 52, the microlens array 54, and the objective lens systems 56 and 58 are arranged in this order from 1 to the photosensitive material 11.

  Here, the lens systems 50 and 52 are configured as magnifying optical systems, and the exposure area 32 by the light beam reflected by the DMD 36 on the photosensitive material 11 is enlarged by enlarging the cross-sectional area of the light beam reflected by the DMD 36. The area (shown in FIG. 2) is enlarged to the required size.

  As shown in FIG. 3, in the microlens array 54, a plurality of microlenses 60 corresponding to the micromirrors 46 of the DMD 36 that reflect the laser light emitted from the light source unit 16 through the optical fibers 28 are integrated. Each microlens 60 is arranged on the optical axis of each laser beam transmitted through the lens systems 50 and 52, respectively.

  The microlens array 54 is formed in a rectangular flat plate shape, and an aperture 62 is integrally disposed in a portion where each microlens 60 is formed. The aperture 62 is configured as an aperture stop disposed in a one-to-one correspondence with each microlens 60.

  As shown in FIG. 3, the objective lens systems 56 and 58 are configured as, for example, an equal magnification optical system. The photosensitive material 11 is disposed at the rear focal position of the objective lens systems 56 and 58. The lens systems 50 and 52 and the objective lens systems 56 and 58 in the projection optical system are shown as one lens in FIG. 3, but a plurality of lenses (for example, a convex lens and a concave lens) are combined. It may be a thing.

  In the image forming apparatus 10 configured as described above, the two-dimensional light detection enables the data of the position, shape and light amount of each light beam irradiated from each exposure head 26 to be measured simultaneously on the recording surface. Means are provided.

  As shown in FIGS. 1 to 3 as a part of the two-dimensional light detection means, the image forming apparatus 10 includes an optical lens device for enlarging the recording surface image on the upstream side in the transport direction of the moving stage 14. A CCD (charge coupled device) camera 100 having an objective lens 102 is disposed. One or a plurality of CCD cameras 100 having the objective lens 102 are installed as necessary. In the present embodiment, a configuration in which three are arranged side by side is employed.

  Each of these CCD cameras 100 is connected to a control unit 20 which is a control means via a lead wire, and is configured to transmit photographed image data to the control unit 20.

  The CCD camera 100 with the objective lens 102 is integrally attached to the upstream edge portion along the transport direction (scanning direction) of the moving stage 14 via the moving operation mechanism 104.

  The moving operation mechanism 104 is configured such that the moving block member 108 can move on the guide rail member 106. The guide rail member 106 is formed in a rail shape having the entire length in the width direction of the moving stage 14 and is installed at the side end of the moving stage 14.

  The moving block member 108 is moved by itself on the guide rail member 106 by a moving mechanism having a drive motor (not shown) controlled by the control unit 20 that is a control means, and is precisely positioned to a required position. Configure to be stoppable. Further, the moving block member 108 is configured such that the CCD camera 100 can be moved in the Z direction perpendicular to the plane (XY plane) of the moving stage 14 and stopped at a required position by a moving operation mechanism or the like (not shown). Instead of providing the movement block member 108 with a movement operation mechanism in the Z direction, a height adjustment mechanism (not shown) that moves the movement stage 14 in the Z direction may be used.

  Next, a structure for adjusting the light amount distribution on the exposure surface provided in the exposure head 26 will be described.

  As shown in FIG. 3, each exposure head 26 is equipped with a light amount distribution adjusting means for improving unevenness of the light amount distribution on the exposure surface (exposure area 32). This light amount distribution adjusting means is configured as a fine movement adjusting mechanism for adjusting the light path position on the light source side incident on the DMD 36 by a small amount in each exposure head 26.

  The fine movement adjusting mechanism constituting the light amount distribution adjusting means is installed at the end of the bundle-like optical fiber 28 that is connected to the exposure head 26 and drawn from the light source unit 16. This fine movement adjusting mechanism urges a pressurizing spring 112, which is a compression coil spring, between the casing 110 of the exposure head 26 and one side of the bundle-like optical fiber 28 and urges it. An electromechanical conversion element (piezoelectric piezoelectric element or the like) 114 is arranged on the other side part of 28 (the side part opposite to the side where the pressurizing spring 112 is arranged).

  The electromechanical transducer 114 is controlled by the control unit 20 to expand and contract the entire length of the piezoelectric element by a required amount, thereby performing an operation of moving and adjusting the bundle-like optical fiber 28 in a direction perpendicular to the optical path. FIG. 3 shows a configuration in which one minute movement adjustment mechanism is provided. However, this minute movement adjustment mechanism has a scanning direction (arrow Y direction) and a direction orthogonal to the scanning direction (arrow X direction). It may be provided corresponding to each and configured to be capable of two-dimensional movement adjustment.

  Next, a structure for adjusting the relative positional relationship between the DMD 36 and the microlens array 54 provided in the exposure head 26 will be described.

  Each exposure head 26 is provided with a position adjusting means for the microlens array 54 as shown in FIGS. This position adjustment means is irradiated from the DMD 36 and an XY adjustment mechanism that moves and adjusts the microlens array 54 in a two-dimensional manner on a plane orthogonal to the optical path, for example, in the X direction and the Y direction orthogonal to each other And a rotation adjusting mechanism that adjusts the rotation around a central axis (a central axis that passes through the approximate center of the exposure area 32 at a right angle) corresponding to the approximate center of the optical path of the light beam.

  This rotation adjusting mechanism includes a ring-shaped driven base member 116 on which a microlens array 54 formed in a rectangular flat plate shape is installed, a support base member 118 that rotatably supports the driven base member 116, and a driven A micro-rotation adjustment mechanism that performs a relative rotation operation between the base member 116 and the support base member 118 is provided.

  The support base member 118 is formed in a ring shape having substantially the same shape as the driven base member 116. Further, since the support base member 118 rotatably supports the driven base member 116 on the same core, although not shown, for example, a cylindrical shaft member is fitted into the ring hole of the support base member 118. The ring hole of the driven base member 116 is assembled around the cylindrical shaft member so that the ring hole of the driven base member 116 can freely rotate, so that the driven base member 116 can freely rotate on the receiving base member 118. Configure.

  In addition, in order to constitute a minute rotation adjusting mechanism, the support base member 118 is provided with two quadrangular columnar support members 120 and 122 projecting in a bowl shape from the outer peripheral surface thereof at a predetermined interval. . Further, on the outer peripheral surface of the driven base member 116, a quadrangular columnar operation projecting member 124 projecting in the radial direction (radiation direction) is projected. Then, both are assembled in a state where the operation projecting member 124 of the driven base member 116 is positioned between the pair of support members 120, 122 of the support base member 118.

  Further, a pressurizing spring 126, which is a compression coil spring, is installed between one support member 120 and the operation projecting member 124 and biased, and an electromechanical conversion element (piezoelectric piezoelectric element or the like) is applied to the other support member 122. 128 is arranged to constitute a minute movement adjustment mechanism.

  The electromechanical conversion element 128 is controlled by the control unit 20 connected by a signal line (not shown) and expands and contracts the entire length of the piezoelectric element by a required amount, thereby moving and operating the operation projecting member 124 and the support base member 118. On the other hand, an operation of rotating and adjusting the microlens array 54 integrated with the driven base member 116 on the concentric shaft is performed.

  Further, in the position adjusting means of the microlens array 54, the rotation adjusting mechanism configured as described above is installed on the XY adjusting mechanism in the position adjusting means of the microlens array 54 so as to be integrally configured.

  For this reason, the support base member 118 of the rotation adjustment mechanism is fixed on the driven table member 130 of the XY adjustment mechanism. The driven table member 130 and the support base member 118 may be formed in an integral structure.

  The driven table member 130 is formed in a rectangular plate shape having an opening formed in a portion corresponding to the microlens array 54, and a rectangular plate formed in the same size and having an opening formed in a portion corresponding to the microlens array 54. In the state where the opening is matched with the plane of the bed member 132 in the form of a plate, it is slidably attached.

  In addition, the driven table member 130 has two sets of opposing side surfaces, and the front end surfaces of the operation end portions of the electromechanical conversion elements (piezoelectric elements, etc.) 134X and 134Y are slidable at the center of one of the side surfaces. The urging end of the pressurizing spring 136, which is a compression coil spring, is slidably slidably contacted with the center of the other side surface (the amount of movement is small, so that the urging end of the pressurizing spring 136 is urged). The end portion may be fixed to the driven table member 130), and the driven table member 130 is in pressure contact with the electromechanical conversion elements 134X and 134Y simultaneously (the driven table member 130 is in contact with the electromechanical conversion elements 134X and 134Y). In a state in which the pressure springs 136 are elastically pressed against each other by the pressurizing springs 136.

  Each electromechanical conversion element (piezo piezoelectric element or the like) 134X, 134Y is connected to the control unit 20 via a signal line (not shown), and is configured to be drive-controllable by the control unit 20.

  In the XY adjustment mechanism in the position adjusting means of the microlens array 54 configured in this way, the control unit 20 drives and controls the electromechanical conversion elements 134X and 134Y, respectively, thereby rotating the microlens array 54 installed. The driven table member 130 on which the mechanism is mounted is guided by the bed member 132 and moved in the XY directions in FIG. 16 by a necessary adjustment distance, thereby enabling two-dimensional position adjustment. Here, the scanning direction is taken as the Y axis, and the direction orthogonal to this is taken as the X axis.

  Next, with the objective lens 102 provided in the image forming apparatus 10 as a two-dimensional light detecting means for simultaneously measuring the position, shape and light quantity data of each light beam irradiated from the exposure head 26 on the recording surface. An exposure surface detection method using the CCD camera 100 will be described. In this exposure surface detection method, image processing and arithmetic processing are performed by the control unit 20 to which the CCD camera 100 is connected, and an image photographed by the CCD camera 100 displayed on the monitor screen provided in the control unit 20. Alternatively, the operator can work while viewing the image-processed data.

  First, a case where the light beam position is detected from an image taken by the CCD camera 100 will be described.

  In this case, the control unit 20 drives and controls the movement operation mechanism 104 to move and set the position of a set of three CCD cameras 100 to a position that matches the exposure area 32 of the exposure head 26 to be measured. To do. At this time, the position in the x direction orthogonal to the scanning direction of the CCD camera 100 is derived from the feed amount that the moving block member 108 has moved on the guide rail member 106. The position in the y direction, which is the scanning direction of the CCD camera 100, is derived from the feed amount of the moving stage 14 in the scanning direction. From the above, the position of the CCD camera 100 is determined.

  Here, when a light beam when a specific pixel (pixel) to be measured in the DMD 36 is turned on, as shown in FIG. The relative position of the light beam with respect to the image sensor is determined by which pixel of the image NO1 photographed by the first CCD camera 100 the light beam ONB1 that is present. Similarly, in the second and third CCD cameras 100, the image sensor of the light beam depends on which pixel of the image NO2 or NO3 the respective positions of the lit light beams ONB2 and ONB3 are captured. Find the relative position with respect to. In principle, the position of a particular light beam can be measured as described above.

  Next, a method for automatically processing an image captured by the CCD camera 100 by the control unit 20 and deriving the pixel position of the reflected light beam will be described.

  Here, it is assumed that the image taken by the CCD camera 100 is, for example, as shown in FIG. In this example, of the two reflected light beams B1 and B2, the right light beam B1 in the drawing is a strong ON light beam, and the left light beam B2 in the drawing has a strength. It is assumed that the light beam B2 is weak and is a stray light beam B2 caused by stray light generated by a positional shift between the DMD 36 and the micro lens array 54.

  Since this CCD camera 100 can detect intensity data for each imaging unit, when the detected intensity distribution is displayed with contour lines D1, D2, and D3, it is as illustrated in FIG. Therefore, a pixel with intensity data that exceeds the threshold value is set for the intensity data of the image, including the meaning of removing noise on the image, using commonly used image processing technology. Binarized image processing is performed in which the intensity of the position is 1 and the intensity data below the threshold is 0. Here, assuming that the boundary between D1 and D2 on the contour line is a threshold value, the data after image processing is as illustrated in FIG.

  In FIG. 10, only the positions B1 and B2 have intensity values, and the intensity is zero at the later positions. In the state where the image processing is performed as shown in FIG. 10, since there is no significant data other than the place where the light beams B1 and B2 exist, the two regions in FIG. 10 are independent light beams B1. , B2 can be automatically recognized.

Therefore, in the subsequent processing, each of the two areas corresponding to the light beams B1 and B2 is processed independently. For example, as shown in FIG. 11, when the center position of the light beam B1 is obtained only for the light beam B1, a pixel at an arbitrary point included in the region of the light beam B1 is (x_i, y_i), and the light beam Assuming that the total number of pixels included in the area of B1 is S, the position coordinate of the center of the light beam B1 is obtained by calculation according to the following equation.
x_c = (Σx_i) ÷ S
y_c = (Σy_i) ÷ S
Although not shown in the figure, the center position coordinate is similarly calculated for the stray light beam B2.

  Next, a light amount detection method for automatically acquiring the light amount of the light beam from the image data acquired by the CCD camera 100 will be described.

  First, the center position of the light beam is automatically calculated from the acquired data obtained by processing the image captured by the CCD camera 100 by the method for detecting the light beam position described above.

  For example, when two light beams B1 and B2 are shown as shown in FIG. 8, the position information about each of the light beams B1 and B2 is (x_c1, y_c1), (x_c2,) as shown in FIG. It is assumed that y_c2) is calculated.

  After obtaining the position information by this calculation, it returns to the original acquired data, and as shown in FIG. 13, for the two light beams B1 and B2 centered on (x_c1, y_c1) and (x_c2, y_c2), respectively. Intensity values are integrated over the entire fixed image area to obtain data corresponding to the light amounts of the light beams B1 and B2.

  Next, a method for automatically calculating the intensity ratio between the light beam B1 and the child beam B2 of the ON pixel from the image data acquired by the CCD camera 100 will be described.

  In this case, the position and the amount of light beam are automatically calculated by processing and calculating the image data acquired by the CCD camera 100 described above. After that, in order to determine which of the two reflected light beams B1 and B2 is the ON pixel light beam B1 in the DMD 36 and which is the child beam B2 caused by stray light, for example, as described in FIG. With respect to the image data binarized by taking the threshold value, the size of the area of each region remaining on the image data is compared to determine the ON light beam and the child beam.

  Based on the discrimination result between the ON light beam and the child beam, the intensity ratio is calculated from the light amount of the ON light beam and the light amount of stray light that is the child beam.

  Next, a method for automatically calculating the beam shape from the image data acquired by the CCD camera 100 will be described.

  For example, it is assumed that when the image is taken by the CCD camera 100, a light beam B1 having an irregular shape is captured as shown in FIG.

  In this case, it is detected from the image data obtained by performing the above-described binarized image processing that the captured light beam B1 is an elliptical beam. At the same time, the length of the minor axis of the elliptical beam can be obtained from the maximum value and the minimum value of x among the position coordinates in the region remaining in the processed image shown in FIG. The long axis length of the elliptical beam can be obtained from the maximum value and the minimum value. The short axis length and the long axis length of the elliptical beam thus obtained are used as parameters representing the light beam shape.

  Next, a method for adjusting the relative positional relationship between the DMD 36 and the microlens array 54 provided in the exposure head 26 by the exposure surface detection method using the CCD camera 100 provided in the image forming apparatus 10 will be described. To do. In carrying out this adjustment method, position adjusting means for the microlens array 54 shown in FIGS. 16 and 17 is used.

  In this microlens array adjustment method, the positional relationship between the field of view and the exposure surface of each CCD camera 100 when the exposure surfaces are imaged by the three CCD cameras 100 is as illustrated in FIG. In other words, the detection area of the first to third CCD cameras 100 covers three nine pixels or more by multiplying the drawing unit of the exposure system by three.

  First, an adjustment method in the case where the relative positional relationship between the DMD 36 and the microlens array 54 is shifted due to translation is described.

  In this adjustment method, the DMD 36 is controlled so that the pixel at the center of the detection area of each CCD camera 100 is lit (ON state).

  Here, when the relative positional relationship between the DMD 36 and the microlens array 54 is shifted in the direction of the arrow X in FIG. The acquired data (NO1, NO2, NO3) is as shown in FIG.

  Therefore, the control unit 20 calculates the center position of the light beam from the acquired data obtained by processing the image captured by the CCD camera 100 by the above-described method of detecting the light beam position. Furthermore, the control unit 20 integrates the intensity values over the entire fixed image areas of the two light beams B1 and B2 based on the position information obtained by this calculation, and the light beams B1 and B2 Data corresponding to the amount of light is derived.

  Then, the control unit 20 calculates the light quantity of each ON light beam B1 (light quantity of the ON pixel) and the light quantity of the stray light B2 that is the child beam from the acquired data (NO1, NO2, NO3) of each CCD camera 100. Thus, an average value P_o of the light amount of the ON pixel B1 and an average value P_a of the light amount of the stray light B2 are obtained.

Here, when the pitch of the microlenses 60 arranged in the microlens array 54 is S, the microlens array 54 is moved by the amount of movement obtained from the following equation by the position adjusting means of the microlens array 54 shown in FIGS. It is moved to improve the relative positional relationship between the DMD 36 and the microlens array 54.
Movement amount = ((P_o−P_a) / (P_o + P_a)) × S
In addition, when the stray light B2 comes out to the right with respect to the figure with respect to ON pixel B1, it moves to the reverse direction to the arrow X of FIG. Alternatively, when the stray light B2 appears downward with respect to the ON pixel B1, the relative position between the DMD 36 and the microlens array 54 is moved by moving the microlens array 54 in the arrow Y direction. Improve relationships.

  Next, an adjustment method in the case where the relative positional relationship between the DMD 36 and the microlens array 54 is shifted due to rotational movement will be described.

  In this case, the acquired data (NO1, NO2, NO3) of the first to third CCD cameras 100 are as shown in FIG.

  Therefore, the control unit 20 calculates the center position of the light beam from the acquired data obtained by processing the image captured by the CCD camera 100 by the above-described method of detecting the light beam position. Furthermore, the control unit 20 integrates the intensity values over the entire fixed image areas of the two light beams B1 and B2 based on the position information obtained by this calculation, and the light beams B1 and B2 Data corresponding to the amount of light is derived.

  Then, the control unit 20 calculates the light quantity of each ON light beam B1 (light quantity of the ON pixel) and the light quantity of the stray light B2 that is the child beam from the acquired data (NO1, NO2, NO3) of each CCD camera 100. Thus, an average value P_o of the light amount of the ON pixel B1 and an average value P_a of the light amount of the stray light B2 are obtained.

Here, if the pitch of the microlenses 60 arranged in the microlens array 54 is S, and the distance of the ON pixel between the first CCD camera 100 (NO1) and the third CCD camera 100 (NO3) is L, FIGS. The relative position relationship between the DMD 36 and the microlens array 54 is improved by moving the microlens array 54 by the rotation amount θ obtained from the following equation by the position adjusting means of the microlens array 54 shown in FIG.
Tanθ = ((P_o−P_a) / (P_o + P_a)) × (S / L)
The microlens array 54 is slightly rotated by the rotation amount θ.

  Next, an adjustment method when the relative positional relationship between the DMD 36 and the microlens array 54 is shifted due to a mixture of parallel movement and rotational movement will be described.

  In this case, the acquired data (NO1, NO2, NO3) of the first to third CCD cameras 100 are as shown in FIG.

  In such a case, first, the parallel movement amount is calculated from the data of the second CCD camera 100 corresponding to the center position of the microlens array 54, and the parallel component of the deviation is removed. The amount of parallel movement at this time is the same as the method described with reference to FIG. Thereafter, the rotation amount θ is obtained in the same manner as the improvement method in the case of the rotational movement described above with reference to FIG. Thus, the relative positional relationship between the DMD 36 and the microlens array 54 is improved.

  Next, a light amount distribution adjusting method in the exposure head 26 by the exposure surface detection method using the CCD camera 100 provided in the image forming apparatus 10 will be described. In carrying out this light quantity distribution adjusting method, a fine movement adjusting mechanism constituting the light quantity distribution adjusting means shown in FIG. 3 is used.

  When the light amount distribution on the exposure surface of one exposure head 26 to be measured is in a state as shown in FIG. 21, the light amount on the exposure surface is the third CCD camera compared to the first CCD camera 100 side. The amount of light on the 100 side is low. The light projected onto the first (NO1), second (NO2), and third (NO3) CCD camera 100 positions corresponds to positions A, B, and C on the DMD 36 surface.

  That is, when the exposure surface has a light amount distribution as shown in FIG. 21, the light amount distribution on the light source side of the exposure head 26 is assumed to be as shown in FIG. 22 on the DMD 36 surface.

  In such a case, the spatial distribution of the light irradiated from the light source unit 16 through each bundled optical fiber 28 and the positional relationship of the DMD 36 are shifted, resulting in a loss of light quantity. Become.

  Therefore, the position of the exit of the bundle-like optical fiber 28 drawn out from the light source unit 16 is moved and adjusted by driving and controlling the electromechanical conversion element 114 of the minute movement adjustment mechanism, so that the unevenness of the light amount distribution on the exposure surface can be reduced. Improve. For example, in the case shown in FIG. 23, the position of the emission end of the bundle-like optical fiber 28 is adjusted by the electromechanical conversion element 114, and the light quantity distribution on the DMD 36 is changed from a dotted line to a solid line.

When the position on the light source side is moved and adjusted in this way, the light amount distribution on the DMD 36 surface is made more uniform, and the light amount distribution on the exposure surface is also improved.
[Operation of Image Forming Apparatus]
Next, the operation of the image forming apparatus 10 configured as described above will be described.

  A light source unit 16 that is a fiber array light source provided in the image forming apparatus 10 is not shown, but collimates a laser beam such as ultraviolet light emitted from each of the laser light emitting elements in a divergent light state by a collimator lens and uses a condensing lens. Condensed light, incident from the incident end face of the core of the multimode optical fiber, propagated in the optical fiber, combined with one laser beam at the laser output portion, and coupled to the output end portion of the multimode optical fiber The light is emitted from the optical fiber 28.

  In the image forming apparatus 10, image data corresponding to the exposure pattern is input to the control unit 20 connected to the DMD 36 and temporarily stored in a memory in the control unit 20. This image data is data representing the density of each pixel constituting the image by binary values (whether or not dots are recorded). This image data is appropriately corrected by the control device based on the drawing distortion amount (distortion state) detected by the drawing distortion amount detecting means described above.

  The moving stage 14 that has adsorbed the photosensitive material 11 to the surface is moved at a constant speed from the upstream side to the downstream side in the transport direction along the guide 30 by a driving device (not shown). When the leading end of the photosensitive material 11 is detected by the position detection sensor 24 attached to the portal frame 22 when the moving stage 14 passes under the portal frame 22, a plurality of lines of image data stored in the memory are obtained. The data is sequentially read out in minutes, and a control signal is generated for each exposure head 26 by a control device as a data processing unit. Based on the generated control signal, each of the micromirrors of the spatial light modulator (DMD) 36 is on / off controlled for each exposure head 26.

  When the spatial light modulator (DMD) 36 is irradiated with laser light from the light source unit 16, the laser light reflected when the micromirror of the DMD 36 is on is imaged at an exposure position for drawing. In this manner, the laser light emitted from the light source unit 16 is turned on / off for each pixel, and the photosensitive material 11 is exposed.

  Further, when the photosensitive material 11 is moved at a constant speed together with the moving stage 14, the photosensitive material 11 is scanned in the direction opposite to the stage moving direction by the exposure head unit 18, and a strip-shaped exposed region is provided for each exposure head 26. 34 (shown in FIG. 2) is formed.

  When the scanning of the photosensitive material 11 by the exposure head unit 18 is completed and the rear end of the photosensitive material 11 is detected by the position detection sensor 24, the moving stage 14 is moved along the guide 30 by the driving device (not shown) in the conveyance direction. It returns to the origin on the upstream side, and again moves along the guide 30 from the upstream side in the transport direction to the downstream side at a constant speed.

  In the image forming apparatus 10 according to the present embodiment, the DMD is used as the spatial light modulation element used in the exposure head 26. For example, a micro electro mechanical systems (SMEM) type spatial light modulation element (SLM) is used. A spatial light modulator other than the MEMS type, such as a modulator, an optical element (PLZT element) that modulates transmitted light by an electro-optic effect, or a liquid crystal light shutter (FLC) can be used in place of the DMD.

  Note that MEMS is a general term for a micro system that integrates micro-sized sensors, actuators, and control circuits based on a micro-machining technology based on an IC manufacturing process. A MEMS-type spatial light modulator is an electrostatic force. It means a spatial light modulation element driven by an electromechanical operation using

  In the image forming apparatus 10 according to the present embodiment, the spatial light modulation element (DMD) 14 used for the exposure head 26 may be replaced with a unit that selectively turns on / off a plurality of pixels. The means for selectively turning on / off the plurality of pixels includes, for example, a laser light source that can selectively emit on / off a laser beam corresponding to each pixel, or each minute laser emission surface. Is arranged corresponding to each pixel to form a surface-emitting laser element, and each micro-laser light-emitting surface can be selectively turned on / off so as to be able to emit light.

  It should be noted that the multi-beam exposure apparatus of the present invention is not limited to the above-described embodiment, and it is needless to say that various other configurations can be adopted without departing from the gist of the present invention.

1 is an overall schematic perspective view of an image forming apparatus according to an embodiment of a multi-beam exposure apparatus of the present invention. FIG. 3 is a schematic perspective view of a main part showing a state in which a photosensitive material is exposed by each exposure head of an exposure head unit provided in the image forming apparatus according to the embodiment of the present invention. 1 is a schematic configuration diagram of an optical system related to an exposure head of an image forming apparatus according to an embodiment of the present invention. It is a principal part expansion perspective view which shows the structure of DMD used for the exposure apparatus which concerns on embodiment of this invention. (A) And (B) is explanatory drawing for demonstrating operation | movement of DMD used for the exposure apparatus which concerns on embodiment of this invention. (A) is a principal part top view which shows the scanning locus | trajectory of the reflected light image (exposure beam) by each micromirror in the image forming apparatus which concerns on embodiment of this invention, when DMD is not inclined, (B) is DMD. It is a principal part top view which shows the scanning trace of the exposure beam at the time of making it incline. It is explanatory drawing which shows a state when image | photographing an exposure area with the CCD camera provided in the image forming apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows the image which image | photographed with the CCD camera provided in the image forming apparatus which concerns on embodiment of this invention, and showed the child light beam by a stray light. It is explanatory drawing which shows the image which displayed the intensity distribution of the ON light beam and the child light beam by a stray light which were image | photographed with the CCD camera provided in the image forming apparatus which concerns on embodiment of this invention by the contour line. Explanatory drawing which shows the image when the image of the ON light beam and the child light beam by the stray light imaged with the CCD camera provided in the image forming apparatus according to the embodiment of the present invention is binarized. It is. It is explanatory drawing which shows the case where the image processing of the ON light beam image | photographed with the CCD camera provided in the image forming apparatus which concerns on embodiment of this invention is binarized, and the center position is calculated | required. It is explanatory drawing which shows the state which image-processes the image of the ON light beam and the child light beam by a stray light image | photographed with the CCD camera provided in the image forming apparatus which concerns on embodiment of this invention, and calculates | requires positional information. The image of the ON light beam and the child light beam caused by stray light, which is captured by the CCD camera provided in the image forming apparatus according to the embodiment of the present invention, is subjected to image processing, and data corresponding to the light amounts of the light beams B1 and B2 is obtained. It is explanatory drawing which shows the state obtained. It is explanatory drawing which shows the state imaged with the shape of the ON light beam image | photographed with the CCD camera provided in the image forming apparatus which concerns on embodiment of this invention becoming distorted. It is explanatory drawing which shows the state when the image which the shape of the ON light beam image | photographed with the CCD camera provided in the image forming apparatus which concerns on embodiment of this invention became distorted performs the image processing of binarization. . FIG. 5 is a perspective view showing a microlens array position adjusting means provided in the exposure head of the image forming apparatus according to the embodiment of the present invention. FIG. 3 is a schematic side view showing a main part of a position adjusting unit of a microlens array provided in an exposure head of an image forming apparatus according to an embodiment of the present invention. The acquired data of each CCD camera in the case where the relative positional relationship between the DMD and the microlens array taken by the CCD camera provided in the image forming apparatus according to the embodiment of the present invention is shifted by translation is shown. It is explanatory drawing. The acquired data of each CCD camera in the case where the relative positional relationship between the DMD and the microlens array taken by the CCD camera provided in the image forming apparatus according to the embodiment of the present invention is rotated and shifted is shown. It is explanatory drawing. Each CCD imaged by the CCD camera provided in the image forming apparatus according to the embodiment of the present invention in the case where the relative positional relationship between the DMD and the microlens array is shifted due to a mixture of parallel movement and rotational movement. It is explanatory drawing which shows the acquisition data of a camera. It is explanatory drawing which shows the state of the light quantity distribution in the exposure surface about the exposure head image | photographed with the CCD camera provided in the image forming apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows the state of the light quantity distribution in DMD surface about the exposure head image | photographed with the CCD camera provided in the image forming apparatus which concerns on embodiment of this invention. It is explanatory drawing which shows the change of light quantity distribution in the DMD surface before and behind light source position adjustment about the exposure head image | photographed with the CCD camera provided in the image forming apparatus which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Photosensitive material 14 Moving stage 16 Light source unit 20 Control unit 26 Exposure head 28 Bundled optical fiber 32 Exposure area 46 Micro mirror 48 Exposure beam 54 Micro lens array 60 Micro lens 100 Camera 102 Objective lens 104 Moving operation mechanism 106 Guide rail member 108 Moving block member 114 Electromechanical conversion element 116 Driven base member 118 Support base member 120 Support member 122 Support member 124 Operation protrusion member 128 Electromechanical conversion element 130 Driven table member 132 Bed member 134X Electromechanical conversion element 134Y Electricity Mechanical conversion element

Claims (3)

In a multi-beam exposure apparatus provided with an exposure head having means for selectively turning on / off a plurality of pixels,
A two-dimensional light detection means for simultaneously measuring the position, shape, and light amount of each light beam emitted from the means for selectively turning on / off a plurality of pixels on the recording surface is provided. Multi-beam exposure system. A microlens array in which a plurality of microlenses corresponding to each pixel of the means for selectively turning on / off the plurality of pixels is formed integrally is formed, and the plurality of pixels are selectively turned on. When a predetermined pixel is turned on by the off / off means and a plurality of light beams are detected by the two-dimensional light detection means, the lighted pixel is detected by detecting the position and light amount of each light beam. And determining the relative positional relationship between the microlens array and the means for selectively turning on / off the plurality of pixels, based on the positional relationship. The relative position of the means for selectively turning on / off the plurality of pixels and the microlens array is adjusted so as to eliminate the stray light by driving and controlling the position adjusting means. Multi-beam exposure apparatus according to Motomeko 1. A light source unit that emits laser light;
A spatial light modulation element for spatially modulating the laser light emitted from the light source unit based on desired image data and irradiating the photosensitive material on the recording surface with the modulated laser light as an exposure beam;
Two-dimensional light detection means for measuring the light amount distribution on the recording surface irradiated from the spatial light modulator;
If the light intensity distribution on the recording surface detected by the two-dimensional light detection means is uneven, the light intensity distribution on the recording surface is made uniform by adjusting the light intensity distribution on the spatial light modulator. Light intensity distribution adjusting means to
A multi-beam exposure apparatus comprising:

Images