JP2007058196A - Image recording device and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress degradation in picture attributed to sensitivity unevenness and sensitivity variation of a recording medium. <P>SOLUTION: When a recording medium having a light-transmitting layer is irradiated with laser light in an image recording device, the transmittance of the light-transmitting layer changes as oscillating as shown in (A) with respect to wavelength changes in the laser light because of the resonance of the laser light. Since the layer thickness of the light-transmitting layer varies within a production allowance, the wavelength-transmittance characteristics in the light-transmitting layer at each portion of the recording medium changes as shown in (B), which results in sensitivity variation in each portion of the recording medium. When the wavelength of laser light changes with temperature change, the sensitivity in each portion of the recording medium changes. Therefore, the recording medium is irradiated with multiplexed laser beams from a plurality of laser light sources, and wavelengths of exiting laser beams from the laser light sources are controlled to be distributed in a range above the resonance minimum wavelength range corresponding to the range from a first wavelength where the transmittance of the light-transmitting layer is maximum and a second wavelength where the transmittance of the light-transmitting layer is minimum and the difference from the first wavelength is minimum (shown in (A)). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image recording apparatus and method, and more particularly, to combine laser beams emitted from a plurality of laser light sources, and combine the laser beams onto a recording medium in which a light transmission layer is provided above an irradiated body. The present invention relates to an image recording apparatus that records an image on a recording medium by irradiating light, and an image recording method applicable to the image recording apparatus.

  As a drawing method when creating a printed wiring board (PWB) or a flat panel display (FPD) board, a mask is conventionally formed by once exposing a wiring pattern to be formed on the board to a film. A method of drawing the wiring pattern on the substrate by surface exposure using this mask after creation (referred to as an analog drawing method) has been common, but in recent years, a digital that represents a wiring pattern without creating a mask. A so-called digital drawing method in which a wiring pattern is directly drawn on a substrate by a drawing device based on data (raster data for drawing) has come to be used.

As an example of a drawing apparatus applicable to this type of digital drawing method, Patent Document 1 discloses that laser light emitted from a single laser light source is modulated by a modulator such as an acousto-optic modulator and deflected by a polygon mirror. A direct writing type printed circuit board scanning device having a configuration in which a wiring pattern or the like is directly drawn on a printed circuit board by scanning on the printed circuit board is disclosed.
Japanese translation of PCT publication No. 2002-520644

  By the way, for miniaturization of various devices equipped with printed wiring boards and high definition of images displayed on flat panel displays, it is important to increase the density of wiring patterns formed on the board. Also, for drawing a wiring pattern on a substrate by a drawing apparatus, it is required to draw the wiring pattern with high resolution with a minimum resolution of about 15 to 20 μm. For this reason, a substrate used for drawing a wiring pattern by a drawing apparatus is a resist in which a light transmitting layer as a support made of PET (polyethylene terephthalate) and having a glossy surface and a photosensitive layer made of a photosensitive material are laminated. The film is attached so that the light transmission layer side is an upper layer, and the wiring pattern is drawn by exposing the wiring pattern to the substrate on which the resist film is attached.

  However, when a wiring pattern is drawn by irradiating a substrate with a resist film attached thereto as described above, the sensitivity to the irradiated laser beam is not constant in each part on the substrate, so-called uneven sensitivity occurs. There is. The width of each line in the wiring pattern drawn on the substrate changes according to the sensitivity to the irradiation laser light at the place where each line is drawn, and the line width becomes narrower as the sensitivity is lowered. For this reason, unevenness in sensitivity in each part on the substrate is undesirable because it causes quality defects such as line width variations and wiring pattern conduction defects in each part of the substrate. In addition, when a semiconductor laser such as an LD (laser diode) is used as the light source, the wavelength of the laser light emitted from the light source varies slightly with the temperature change of the light source, but the wavelength of the laser light emitted from the light source is There is also a problem that the sensitivity to the irradiated laser light at each portion on the substrate changes only by a slight deviation.

  The present invention has been made in view of the above facts, and an object of the present invention is to provide an image recording apparatus and an image recording method capable of recording an image so as to suppress image quality deterioration due to uneven sensitivity of the recording medium and sensitivity change. .

  The inventors of the present application have a phenomenon in which the sensitivity to the irradiated laser light is uneven in each part on the substrate, or the sensitivity to the irradiated laser light in each part on the substrate changes with a slight shift in the wavelength of the irradiated laser light. Estimated that the resonance of the laser beam in the light-transmitting layer of the resist film attached to the substrate was related, and measured the change in the light transmittance of the light-transmitting layer with respect to the change in the wavelength of the irradiated light An experiment was conducted. In this experiment, a film made of PET (indicated as “13 μm product” in FIG. 1) with a nominal film thickness of 13 μm (actual film thickness of 13.155 μm) that is actually used as a light transmission layer and a nominal film thickness of Using PET film of 18 μm (actual film thickness is 18.6 μm) (indicated as “18 μm product” in FIG. 1), each PET film is irradiated with light and the amount of light transmitted through each PET film (light transmittance) Was measured for each wavelength with a spectroscope. The refractive index n of each PET film is 1.63. The experimental results are shown in FIG.

  As is clear from FIG. 1, the above experiment confirmed that the light transmittance oscillates at a substantially constant period with respect to the change in the wavelength of the irradiated light in any PET film. In addition, in the PET film having a nominal film thickness of 13 μm, the wavelengths with the maximum light transmittance in the wavelength range of 400 to 410 nm are 400.8 nm, 404.6 nm, 408.4 nm, and the wavelengths with the minimum light transmittance are In a PET film having a film thickness of 402.7 nm and 406.5 nm and a nominal film thickness of 18 μm, the wavelengths having the maximum light transmittance in the wavelength range of 400 to 410 nm are 401.6 nm, 404.2 nm, and 407 nm.

  As an example, as shown in FIG. 2, when a spatial beam, which is a coherent light wave, is vertically incident on a pair of semitransparent plane mirrors # 1 and # 2 arranged in parallel from the semitransparent plane mirror # 1 side, Part of the spatial beam is reflected by the translucent plane mirror # 1 and the rest reaches the translucent plane mirror # 2, but some of this is reflected by the translucent plane mirror # 2 and translucent plane mirror # 1, # Round trip between the two. When the distance L between the semitransparent plane mirrors # 1 and # 2 is an integer multiple of the spatial beam wavelength / 2, a standing wave is generated and resonance occurs, and the light transmittance of the semitransparent plane mirrors # 1 and # 2 ( The power transmission) shows a maximum value. The resonator shown in FIG. 2 is called a Fabry-Perot resonator, and the power transmittance T in this resonator is n for the refractive index of the medium between the translucent flat mirrors # 1 and # 2, and When the power reflectance in reflection is R, it is expressed by the following equation (1).

Further, by substituting k ₀ = 2π / λ into k ₀ in the equation (1), a transmittance characteristic representing a change in power transmittance T (light transmittance) with respect to a change in wavelength λ of the spatial beam can be obtained. .

Here, the measurement conditions (refractive index n = 1.63, interval L = 13.155 μm, power reflectivity R = 0.05 (PET reflectivity)) for a PET film having a nominal film thickness of 13 μm are substituted into the above equation (1). In addition, when substituting k ₀ = 2π / λ and calculating the change in power transmittance T (light transmittance) within the wavelength range of 400 to 412 nm, the same wavelength as the experimental result is obtained as the wavelength at which the light transmittance is maximized. (400.8 nm, 404.6 nm, 408.4 nm) were derived, and the same wavelength (402.7 nm, 406.5 nm) as the experimental result was derived for the wavelength at which the light transmittance was minimized. Therefore, it can be determined that the vibrational change of the light transmittance with respect to the wavelength change as shown in FIG. 1 is caused by the resonance of the laser light in the light transmission layer of the resist film.

  Based on the experimental results described above, the inventors of the present invention have uneven sensitivity to irradiation laser light in each part on the substrate because the thickness of the light transmission layer of the resist film in each part on the substrate is within the manufacturing tolerance. Because of the variation, the wavelength (resonance wavelength) at which the light transmittance of the light transmission layer is maximized in each part on the substrate varies, and accordingly, the light corresponding to the laser beam having a certain wavelength in each part on the substrate. This is because the light transmittance of the transmission layer varies (the apparent light intensity of each part on the substrate varies depending on the part of the substrate. It appears as a variation in sensitivity). In addition, the inventors of the present application also deal with the phenomenon in which the sensitivity to the irradiation laser light at each part on the substrate changes with a slight change in the wavelength of the irradiation laser light. This is because the light transmittance of the light transmission layer with respect to the irradiated laser light after the wavelength change and the wavelength change is different in each part on the substrate (with the change of the wavelength of the irradiated laser light, The light transmittance of the light transmission layer with respect to the irradiation laser light changes in each part, and the amount of irradiation laser light transmitted through the light transmission layer in each part on the substrate changes from before the wavelength change. The sensitivity in each part seems to have changed.

  Based on the above, the image recording apparatus according to the first aspect of the present invention is a recording medium including a photosensitive layer and a light transmission layer provided above the photosensitive layer by combining laser beams emitted from a plurality of laser light sources. An image recording apparatus for recording an image on the recording medium by irradiating the combined laser light on the plurality of laser light sources, wherein each of the laser light sources has a wavelength of the emitted laser light The difference between the first wavelength at which the transmittance is maximized and the light transmittance of the light transmitting layer is minimized and the difference between the first wavelength and the second wavelength at which the difference is minimum is equal to or greater than the resonance minimum wavelength range. It is characterized by being distributed within a predetermined wavelength range.

  The image recording apparatus according to the first aspect of the invention irradiates a recording medium including a photosensitive layer and a light transmission layer provided on the photosensitive layer by combining laser beams emitted from a plurality of laser light sources. As a result, an image is recorded on the recording medium. Here, when the layer thickness of the light transmission layer in each part on the recording medium varies within the manufacturing tolerance, the resonance wavelength of the light transmission layer in each part on the recording medium also varies, and this resonance wavelength variation Appears as a variation in sensitivity in each part of the recording medium, and this variation in sensitivity causes deterioration of the image quality of an image recorded on the recording medium. In addition, even when the wavelength of the laser light emitted from the laser light source changes due to a change in the ambient temperature of the laser light source, the light transmittance of the light transmission layer with respect to the irradiation laser light changes in each part on the recording medium, This change in light transmittance appears as a change in sensitivity in each part of the recording medium, and this change in sensitivity causes image quality degradation of images recorded on the recording medium.

  On the other hand, according to the first aspect of the present invention, the wavelength of the emitted laser light from each of the plurality of laser light sources is such that the light transmittance of the light transmitting layer is maximized as shown in FIG. The light transmittance of the first wavelength and the light transmission layer is minimized, and the difference between the first wavelength and the first wavelength is distributed within a predetermined wavelength range equal to or greater than the minimum resonance wavelength range corresponding to the second wavelength. It has been established. As a result, the wavelength of the laser light applied to the recording medium is also distributed within a predetermined wavelength range that is equal to or greater than the above-mentioned resonance minimum wavelength range, so that the laser light transmitted through the light transmission layer in each part on the recording medium Variations and changes in the amount of light transmitted through the light-transmitting layer of the laser light in each portion on the recording medium due to variations in the amount of light and variations in the emission wavelength of the laser light source are suppressed.

  As an example, the number of laser light sources is two, and the wavelengths of the laser beams emitted from the individual laser light sources are distributed within the minimum resonance wavelength range as shown as laser beams A and B in FIG. Think if you are. The wavelength-light transmittance characteristics of the light transmission layer in each part on the recording medium are shown in FIG. 3B as “the thickness of the light transmission layer due to the variation in the layer thickness of the light transmission layer in each part on the recording medium. It shifts along the wavelength axis as indicated by “variation due to variation”. Further, the wavelength itself of the laser light emitted from the laser light source is also shown as “variation caused by fluctuation of the ambient temperature of the laser light source” in FIG. Shift along the wavelength axis. For this reason, the amount of light transmitted through the light-transmitting layer of the laser light emitted from a single laser light source is affected by variations in the thickness of the light-transmitting layer in each part on the recording medium and fluctuations in the ambient temperature of the laser light source. In each part on the medium, the maximum light transmittance (light transmittance at the resonance wavelength (first wavelength)) and the minimum light transmittance (light at the second wavelength) of the wavelength-light transmittance characteristics of the light transmitting layer. It fluctuates with a light amount difference corresponding to the difference in transmittance.

  On the other hand, when the laser beams A and B emitted from the two laser light sources are combined and applied to each part on the recording medium, the wavelength of the laser beam A resonates among the parts on the recording medium. In a portion that matches the wavelength (first wavelength) and the amount of light transmitted through the light transmission layer of the laser light A is maximum, the wavelength of the laser light B does not match the first wavelength. Since the amount of light transmitted through the transmission layer is smaller than the maximum value, the amount of light transmitted through the light transmission layer of the irradiation laser light (laser light obtained by combining laser beams A and B) in the portion is smaller than the maximum value. Similarly, in each part on the recording medium, the wavelength of the laser light B is the part where the wavelength of the laser light A coincides with the second wavelength and the light transmission layer transmission light amount of the laser light A shows the minimum value. Is not coincident with the second wavelength, the amount of light transmitted through the light transmission layer of the laser beam B is larger than the minimum value, so that the light of the irradiation laser beam (laser beam obtained by combining the laser beams A and B) in that portion The amount of light transmitted through the transmission layer is smaller than the minimum value. Accordingly, the fluctuation range of the light transmission layer transmitted light amount of the entire irradiated laser light in each part on the recording medium is smaller than that in the case of using laser light emitted from a single laser light source.

  In the above example, the laser beams emitted from the two laser light sources are combined and irradiated to each part on the recording medium. The laser beams emitted from three or more laser light sources are combined. Even when irradiating each part on the recording medium, if the wavelength of the laser light emitted from each laser light source is distributed within the wavelength range equal to or greater than the resonance minimum wavelength range, the recording medium is similar to the above. The fluctuation range of the amount of light transmitted through the light transmission layer of the irradiation laser light in each of the upper portions becomes small. As the fluctuation range of the amount of light transmitted through the light transmission layer of the irradiated laser light in each part on the recording medium is reduced, the sensitivity variation in each part of the recording medium is reduced and the ambient temperature of the laser light source is changed. As a result, the change in sensitivity in each part of the recording medium when the wavelength of the laser light emitted from the laser light source changes is also reduced. Therefore, according to the first aspect of the present invention, it is possible to record an image so as to suppress deterioration in image quality due to unevenness of sensitivity of the recording medium and change in sensitivity.

  The predetermined wavelength range in the invention described in claim 1 may be a wavelength range that is twice or more the minimum resonance wavelength range as described in claim 2, for example, or as described in claim 3 The wavelength range may be four times or more the minimum resonance wavelength range. As described above, the distribution of the wavelengths of the laser beams emitted from a plurality of laser light sources over a wider frequency range (preferably as uniform as possible within the frequency range) makes irradiation on each part of the recording medium. The amount of laser light transmitted through the light transmission layer can be made more uniform. However, when the sensitivity of the photosensitive layer is not constant with respect to the wavelength change of the irradiation laser light, the sensitivity of the photosensitive layer itself is recorded even if the light transmission layer transmission amount of the irradiation laser light in each part of the recording medium becomes uniform. Since there is a possibility that each part of the medium may vary, the upper limit of the width of the predetermined wavelength range in the invention according to claim 1 may be set in consideration of a change in sensitivity of the photosensitive layer accompanying a change in wavelength of the irradiation laser light. desirable.

  Further, in the invention according to any one of claims 1 to 3, the plurality of laser light sources may be configured such that, for example, the wavelength of each emitted laser beam is distributed within a predetermined wavelength range and light is emitted. It is preferable that the light transmittance of the transmission layer is determined so as to have different wavelengths. As a result, fluctuations in the amount of light transmitted through the light transmission layer of the irradiated laser light in each part on the recording medium can be suppressed with higher accuracy, and deterioration in image quality due to unevenness of sensitivity and changes in sensitivity can be suppressed with higher accuracy. it can.

  Also, in the invention according to any one of claims 1 to 3, the image recording apparatus, as described in claim 5, for example, changes an emission direction of a light beam incident on a modulation surface provided with a plurality of modulation regions. A surface modulation element that can be controlled independently with each of the partial light beams incident on the individual modulation regions as a unit, and a laser light beam that combines laser beams emitted from a plurality of laser light sources is converted into a modulation surface of the surface modulation element And a plurality of partial laser light beams emitted in a predetermined direction by the surface modulation element among the incident laser light beams were emitted from different modulation regions of the surface modulation element to each part on the recording medium. It is preferable that the image is recorded on the recording medium by guiding the partial laser beams so that at least a part of each of the partial laser beams is irradiated.

  When the wavelengths of laser beams emitted from a plurality of laser light sources are distributed within a certain wavelength range as in the present invention, the laser beams emitted from the plurality of laser light sources are combined even if they are combined. The distribution wavelength range of the laser beam (laser beam) is not necessarily uniform in each part of the laser beam (the partial wavelength ranges in each of the plurality of partial laser beams forming the laser beam as a whole may be different) There is). On the other hand, in the invention according to claim 5, the emission direction of the light beam incident on the modulation surface provided with a plurality of modulation areas is controlled independently for each partial light beam incident on each modulation area. A laser light beam obtained by combining laser beams emitted from a plurality of laser light sources is incident on the modulation surface of the surface modulation element, and a predetermined direction is determined by the surface modulation element of the incident laser light beam. In a configuration in which an image is recorded on a recording medium by irradiating the recording medium with a plurality of partial laser beams emitted to the portion, the portions emitted from different modulation areas of the surface modulation elements are formed on each portion of the recording medium. Since at least a part of each of the laser beams is irradiated repeatedly, even if the distribution wavelength ranges of the partial laser beams incident on the individual modulation regions of the surface modulation element are different, By partially irradiating at least a portion of the partial laser light fluxes having different distribution wavelength ranges, the exposure amount (integrated value of the laser light irradiation amount) on each portion on the recording medium can be made uniform. And the image quality of the recorded image can be improved.

  According to a sixth aspect of the present invention, there is provided an image recording method comprising: combining a laser beam emitted from a plurality of laser light sources onto a recording medium including a photosensitive layer and a light transmission layer provided on the photosensitive layer. Thus, in the image recording method for recording an image on the recording medium, the wavelength of the laser beam emitted from each of the plurality of laser light sources is a first wavelength at which the light transmittance of the light transmission layer is maximized. And the light transmittance of the light transmissive layer is minimized and the difference from the first wavelength is distributed in a predetermined wavelength range equal to or greater than the resonance minimum wavelength range corresponding to the minimum second wavelength. Therefore, similarly to the first aspect of the invention, it is possible to record an image so as to suppress deterioration in image quality due to uneven sensitivity of the recording medium and sensitivity change.

  As described above, the present invention irradiates a laser beam emitted from a plurality of laser light sources onto a recording medium including a photosensitive layer and a light transmission layer provided on the photosensitive layer, and records an image. The difference between the wavelength of the emitted laser light of each of the plurality of laser light sources is the difference between the first wavelength at which the light transmittance of the light transmitting layer is maximized and the first wavelength at which the light transmittance of the light transmitting layer is minimized. Since it is determined to be distributed within a predetermined wavelength range that is equal to or greater than the resonance minimum wavelength range corresponding to the minimum second wavelength, an image is recorded so that the image quality deterioration due to the sensitivity variation of the recording medium and the sensitivity change is suppressed. It has the excellent effect of being able to.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

[Configuration of image exposure apparatus]
FIG. 4 shows the appearance of the image exposure apparatus 100 according to the present embodiment. The image exposure apparatus 100 corresponds to the image recording apparatus according to the present invention, and includes a flat plate-like moving stage 152 that holds a sheet-like recording medium 150 by adsorbing to the surface. Two guides 158 extending along the stage moving direction are installed on the upper surface of the thick plate-like installation table 156 supported by the four legs 154, and the moving stage 152 has a longitudinal direction thereof. The guide 158 is arranged so as to be parallel to the longitudinal direction (stage moving direction / sub-scanning direction), and is supported by the guide 158 so as to be reciprocally movable. The moving stage 152 is moved along the guide 158 by a stage driving device 304 (see FIG. 20, details will be described later).

  A U-shaped gate 160 is provided at the center of the installation table 156 so as to straddle the movement path of the movement stage 152. Both ends of the gate 160 are fixed to both side surfaces of the installation table 156, respectively. Above the moving path of the moving stage 152, a scanner 162 is disposed on one side across the gate 160, and a plurality of (for example, two) sensors for detecting the leading end and the trailing end of the recording medium 150 on the opposite side. 164 is disposed. The scanner 162 and the sensor 164 are respectively attached to the side surfaces of the gate 160. The scanner 162 and the sensor 164 are connected to a controller (not shown) that controls them.

  The image exposure apparatus 100 is an apparatus having a function of directly drawing a wiring pattern represented by input image data (drawing raster data) on a substrate (recording medium 150) by a digital drawing method. It is used when manufacturing a printed wiring board for mounting these parts and a color filter substrate for a flat panel display. For example, when a printed wiring board is manufactured, a recording medium 150 as shown in FIG. 5C is set on the moving stage 152, for example. The recording medium 150 is manufactured as follows.

  That is, as a substrate used for manufacturing a printed wiring board, for example, a conductive layer 104B made of copper and having a thickness of about 18 μm is formed on the front and back surfaces of a flat substrate 104A made of glass epoxy and having a thickness of about 200 μm. The formed substrate 104 is used. A resist film 106 shown in FIG. 5A is prepared separately from the substrate 104. The resist film 106 is made of a photosensitive material and has a thickness of about 15 to 30 μm. The resist layer 106 is made of PET and has a nominal thickness of 13 μm (actual thickness is 13.15 μm) or a nominal 18 μm (actual thickness is 18.6 μm). ) And a back layer 112 made of polyethylene or polypropylene and having a thickness of about 20 to 25 μm. The light transmission layer 110 of the resist film 106 functions as a support and enables the image exposure apparatus 100 to draw a wiring pattern on the recording medium 150 with a minimum resolution of about 15 to 20 μm. Has gloss on the surface.

  Although the resist film 106 is wound in a roll shape, the recording medium 150 is drawn from the roll when the recording medium 150 is manufactured, and after the back layer 112 is peeled as shown in FIG. 5B, the resist film 106 is shown in FIG. In this manner, the light-transmitting layer 110 is overlaid on the substrate 104 so that the light-transmitting layer 110 side is an upper layer (so that the photosensitive layer 108 is in contact with the substrate 104). The resist film 106 is attached to the substrate 104 by being laminated by a laminator (not shown) while the photosensitive layer 108 is in close contact with the substrate 104. Thereby, the recording medium 150 is produced. Note that the recording medium 150 used when manufacturing the color filter substrate is manufactured by adhering the resist film 106 to a glass substrate instead of the substrate 104.

On the other hand, as shown in FIGS. 6 and 7B, the scanner 162 of the image exposure apparatus 100 has a plurality of (for example, 14) exposures arranged in a substantially matrix of m rows and n columns (for example, 3 rows and 5 columns). A head 166 is provided. 6 and 7B show an example in which four exposure heads 166 are arranged in the third row in relation to the width of the recording medium 150. FIG. Hereinafter, the exposure head 166 in the m-th row and the n-th column is referred to as an exposure head 166 _mn . As shown in FIG. 7B, the exposure area 168 by each exposure head 166 has a rectangular shape with the short side in the sub-scanning direction. Accordingly, as the moving stage 152 moves, a strip-shaped exposed area 170 (see FIG. 7A) is formed on the recording medium 150 for each exposure head 166. Hereinafter, an exposure area by the exposure head 166 in the m-th row and the n-th column is referred to as an exposure area 168 _mn .

As shown in FIG. 7B, the exposure heads 166 in the same row are arranged along the main scanning direction (direction orthogonal to the sub-scanning direction), but the individual exposure heads 166 in the same column are band-shaped. The exposed areas 170 are arranged on the recording medium 150 without gaps along the main scanning direction (see FIG. 7A), and a predetermined distance along the main scanning direction with respect to the adjacent exposure heads 166 in the same row. They are arranged at different positions (for example, a distance equal to the length of the long side of the exposure area 168). Therefore, the gap between the exposure area 168 ₁₁ of the exposure head 166 _{11 in} the first row and the first column and the exposure area 168 ₁₂ of the exposure head 166 _{12 in} the first row and the second column is the exposure head 166 in the second row and the first column. will be exposed by the exposure area _{168 31} of the exposure heads _{166 31} the exposure area _{168 21} and third row first column _21.

As shown in FIGS. 8 and 9, the exposure heads 166 _{11 to} 166 _mn are digital devices manufactured by Texas Instruments, Inc. as spatial light modulators that modulate the incident light beam for each pixel in accordance with image data. -Each is provided with a micromirror device (DMD) 50. The DMD 50 is connected to a controller 302 (see FIG. 20, details will be described later) having a data processing unit and a mirror drive control unit. The data processing unit of the controller 302 generates a control signal for driving and controlling each micromirror in the region to be controlled in the DMD 50 for each exposure head 166 based on the input image data. The area to be controlled will be described later. The mirror drive control unit controls the angle of the reflection surface of each micromirror of the DMD 50 for each exposure head 166 based on the control signal generated by the image data processing unit. The control of the angle of the reflecting surface will be described later.

  On the light incident side of the DMD 50, the emission ends (light emitting points) of a plurality of optical fibers form a rectangular shape as in the exposure area 168 as a whole, and the long side direction is in the long side direction of the exposure area 168. A fiber array light source 66 having a laser emitting portion arranged so as to coincide with a corresponding direction, a lens system 67 for correcting the laser light emitted from the fiber array light source 66 and condensing it on the DMD, and a lens system 67 A mirror 69 that reflects the transmitted laser light toward the DMD 50 is sequentially arranged.

  Although schematically shown in FIG. 8, the lens system 67 is transmitted through the condenser lens 71 and the condenser lens 71 for condensing the laser light B emitted from the fiber array light source 66, as shown in FIG. A rod-shaped optical integrator (hereinafter referred to as a rod integrator) 72 inserted in the optical path of the laser beam B, and an imaging lens 74 arranged on the laser beam emission side of the rod integrator 72 are configured. The rod integrator 72 is, for example, a translucent rod formed in a square columnar shape, and the laser beam B incident on the rod integrator 72 has a uniform intensity distribution in the beam cross section while traveling while totally reflecting inside. The An antireflection film is formed on the entrance end face and exit end face of the rod integrator 72 in order to improve the light transmittance. The laser light emitted from the fiber array light source 66 is converted into a light beam that is close to parallel light and has a uniform intensity in the beam cross section by the condensing lens 71, the rod integrator 72, and the imaging lens 74 of the lens system 67. Then, the light is reflected by a mirror 69 arranged on the laser light emission side of the lens system 67 and is irradiated to the DMD 50 through a TIR (total reflection) prism 70. In FIG. 8, illustration of the TIR prism 70 is omitted.

  An imaging optical system 51 that images the laser beam B reflected by the DMD 50 on the recording medium 150 is disposed on the laser beam emission side of the DMD 50. Although the imaging optical system 51 is schematically shown in FIG. 8, as shown in FIG. 9, the first imaging optical system including the lens systems 52 and 54 and the second connection including the lens systems 57 and 58 are provided. The image optical system includes a microlens array 55 and an aperture array 59 inserted between these image forming optical systems.

  The microlens array 55 is configured by two-dimensionally arranging a large number of microlenses 55a corresponding to the respective pixels of the DMD 50. In the present embodiment, as described later, only 1024 × 256 rows of the 1024 × 768 rows of micromirrors of the DMD 50 are driven, and accordingly, 1024 × 256 rows of microlenses 55a are arranged. . The arrangement pitch of the micro lenses 55a is 41 μm in both the vertical and horizontal directions. As an example, the microlens 55a has a focal length of 0.19 mm, an NA (numerical aperture) of 0.11, and is formed from the optical glass BK7. The beam diameter of the laser beam B at the position of each microlens 55a is 41 μm. The aperture array 59 is formed by forming a large number of apertures (openings) 59a corresponding to the microlenses 55a of the microlens array 55. In the present embodiment, the diameter of the aperture 59a is 10 μm.

  The first imaging optical system forms an image on the microlens array 55 by enlarging the image by the DMD 50 three times. The second imaging optical system enlarges the image passing through the microlens array 55 by 1.6 times, and forms and projects the image on the recording medium 150. Therefore, as a whole, the image formed by the DMD 50 is magnified 4.8 times and formed on the recording medium 150 and projected. In this embodiment, a prism pair 73 is disposed between the second imaging optical system and the recording medium 150. By moving the prism pair 73 in the vertical direction in FIG. The focus of the image above can be adjusted. The recording medium 150 is conveyed in the direction of arrow F (sub-scanning direction) in FIG.

  As shown in FIG. 10, in the DMD 50, a large number (for example, 1024 × 768) of micromirrors (micromirrors) 62, each constituting a pixel (pixel), are arranged on a SRAM cell (memory cell) 60 in a lattice pattern. This is a mirror device. In each pixel, a micromirror 62 supported by a support column is provided at the top, and a material having high reflectance such as aluminum is deposited on the surface of the micromirror 62. The reflectance of the micromirror 62 is 90% or more, and the arrangement pitch is 13.7 μm in both the vertical and horizontal directions. A silicon gate CMOS SRAM cell 60 manufactured in a normal semiconductor memory manufacturing line is disposed directly below the micromirror 62 via a support including a hinge and a yoke, and the entire structure is monolithic. ing.

  In the DMD 50, when a digital signal is written to the SRAM cell 60, the micromirror 62 supported by the support is within a range of ± α degrees (for example, ± 12 degrees) with respect to the substrate side on which the DMD 50 is disposed with the diagonal line as the center. Be inclined. FIG. 11A shows a state where the micromirror 62 is turned on and tilted by + α degrees, and FIG. 11B shows a state where the micromirror 62 is turned off and tilted by −α degrees. Therefore, by controlling the tilt of the micromirror 62 in each pixel of the DMD 50 according to the image signal as shown in FIG. 10, the laser light B incident on the DMD 50 is reflected in the tilt direction of each micromirror 62. The FIG. 10 shows an example of a state in which a part of the DMD 50 is enlarged and the micromirror 62 is controlled to + α degrees or −α degrees. On / off control of each micromirror 62 is performed by a controller 302 connected to the DMD 50. A light absorber (not shown) is arranged in the emission direction of the laser beam B reflected by the micromirror 62 in the off state.

Further, it is preferable that the DMD 50 is arranged with a slight inclination so that the short side forms a predetermined angle θ (for example, 0.1 ° to 5 °) with the sub-scanning direction. 12A shows the scanning trajectory of the reflected light image (exposure beam) 53 by each micromirror when the DMD 50 is not tilted, and FIG. 12B shows the scanning trajectory of the exposure beam 53 when the DMD 50 is tilted. Show. In the DMD 50, a number of micromirror arrays in which a large number (for example, 1024) of micromirrors are arranged in the longitudinal direction are arranged in a short direction (for example, 756), but as shown in FIG. to, by inclining the DMD 50, the pitch P ₁ of the scanning locus of the exposure beams 53 from each micromirror (scanning line), since the narrower than the pitch P ₂ of the scanning lines if not inclined DMD 50, significantly resolution Can be improved. On the other hand, the inclination angle of the DMD 50 is small, the scanning width _{W 2} in the case of tilting the DMD 50, which is substantially equal to the scanning width _{W 1} when not inclined DMD 50.

  Further, by tilting the DMD 50, the same scanning line is overlapped and exposed (multiple exposure) by different micromirror rows. In this way, by performing multiple exposure on the same scanning line, a minute amount of the exposure position with respect to the alignment mark can be controlled, and high-definition exposure can be realized. Further, joints between a plurality of exposure heads arranged in the main scanning direction can be connected without a step by a slight amount of exposure position control. The same effect can be obtained by arranging the micromirror rows in a staggered manner instead of inclining the DMD 50.

Based on the above, in the present embodiment, as shown in FIG. 21, the DMD 50 is tilted so that the exposure area 168 is tilted by the tilt angle θ = ± tan ⁻¹ (n / L) with respect to the sub-scanning direction. Has been placed. In FIG. 21, the exposure area 168 obtained by a single DMD 50 is divided into K regions (divided regions 168D) for each of L rows × M columns along the sub-scanning direction, and n is L. On the other hand, it is a relatively prime natural number or a number equal to L. In FIG. 21, n = 1, and the clockwise direction when viewed from the scanning line L1 is the positive direction of the inclination direction. As an example, in FIG. 21, L = 4, M = 32, and K = 5, but actually, a single exposure area 168 is configured by a larger number of exposure beams 53.

By tilting the exposure area 168 as described above, the pitch of the scanning trajectory (scanning line) of the exposure beam 53 by each micromirror becomes narrower than when the exposure area 168 is not tilted, and the resolution can be improved. Further, since the inclination angle θ of the exposure area 168 with respect to the sub-scanning direction is set to θ = ± tan ⁻¹ (n / L), each scanning line is respectively reflected by the reflected light image (exposure beam) 53 of each divided region 168D. As a result, each scanning line is exposed to multiple (K times) exposure beams 53 reflected by different micromirrors 62 of the DMD 50. For example, paying attention to the scanning line L1 shown in FIG. 21, a single exposure beam 53 (see the exposure beam 53 indicated by “●” in FIG. 21) of each divided region 168D scans on the scanning line L1, respectively. As a result, it is exposed five times. In this way, by performing multiple exposure, it is possible to eliminate variation in image density and obtain an image with uniform density.

  That is, the individual exposure beams 53 constituting the exposure area 168 (corresponding to the partial laser beam according to claim 5) may have slight variations in the amount of light, and the distribution wavelength range is not uniform. For this reason, if only a single exposure beam 53 is scanned on each scanning line, the light transmittance of the light transmission layer 110 due to variations in the amount of light of the exposure beam 53 and non-uniformity in the distribution wavelength range. Fluctuations) appear as variations in image density on the corresponding scanning line, and variations in density occur in images exposed and recorded on the recording medium 150. On the other hand, in this embodiment, multiple exposure is performed by scanning each scanning line with a plurality of exposure beams 53. Therefore, the exposure amount of the exposure beam 53 on each part of the recording medium 150 (irradiation of the exposure beam 53). (Integrated value of light quantity) can be made uniform, and the density of the image to be exposed and recorded on the recording medium 150 can be made uniform.

  The DMD 50 corresponds to the surface modulation element according to claim 5, and the surface of the DMD 50 on which the micromirror 62 is provided (the surface on which laser light is incident) is the modulation surface according to claim 5. Of the laser light incident surface, regions corresponding to the individual micromirrors 62 provided on the laser light incident surface correspond to the modulation regions according to claim 5, respectively.

  As shown in FIG. 13, the fiber array light source 66 includes a plurality of (for example, 14) laser modules 64, and one end of the multimode optical fiber 30 is coupled to each laser module 64. An optical fiber 31 having the same core diameter as that of the multimode optical fiber 30 and a smaller cladding diameter than the multimode optical fiber 30 is coupled to the other end of the multimode optical fiber 30. As shown in detail in FIG. 14, seven end portions of the multimode optical fiber 31 opposite to the optical fiber 30 are arranged along the main scanning direction orthogonal to the sub-scanning direction, and they are arranged in two rows to form a laser. An emission unit 68 is configured. As shown in FIG. 14, the laser emitting portion 68 constituted by the end portion of the multimode optical fiber 31 is sandwiched and fixed between two support plates 65 having a flat surface. In addition, a transparent protective plate such as glass is preferably disposed on the light emitting end face of the multimode optical fiber 31 for protection. The light exit end face of the multimode optical fiber 31 is easily collected and easily deteriorated due to its high light density. However, by arranging the protective plate as described above, the dust adheres to the end face and is deteriorated. Can be delayed.

  As shown in FIG. 15, in this embodiment, an optical fiber 31 having a length of about 1 to 30 cm and having a small cladding diameter is coaxially coupled to a tip portion of the multimode optical fiber 30 having a large cladding diameter on the laser light emission side. ing. These optical fibers 30 and 31 are coupled by fusing the incident end face of the optical fiber 31 to the outgoing end face of the optical fiber 30 in a state where the respective core axes coincide. As the multimode optical fiber 30 and the optical fiber 31, any of a step index type optical fiber, a graded index type optical fiber, and a composite type optical fiber can be applied. For example, a step index type optical fiber manufactured by Mitsubishi Cable Industries, Ltd. can be used. In the present embodiment, the multimode optical fiber 30 and the optical fiber 31 are step index type optical fibers, and the multimode optical fiber 30 has a cladding diameter = 125 μm, a core diameter = 50 μm, NA = 0.2, and the transmittance of the incident end face coating. = 99.5% or more, and the optical fiber 31 has a cladding diameter = 60 μm, a core diameter = 50 μm, and NA = 0.2.

  The laser module 64 is composed of a combined laser light source (fiber light source) shown in FIG. This combined laser light source includes a plurality of (for example, seven) chip-like lateral multimode or single mode GaN-based semiconductor lasers LD1, LD2, LD3, LD4, LD5, LD6, and LD7 arranged and fixed on the heat block 10. A collimator lens 11, 12, 13, 14, 15, 16, and 17 provided corresponding to each of the semiconductor lasers LD1 to LD7, a single condenser lens 20, and one multimode optical fiber 30. It consists of The number of semiconductor lasers LD is not limited to seven, but may be other numbers. Further, instead of the seven collimator lenses 11 to 17, a collimator lens array in which these lenses are integrated can be used. The semiconductor lasers LD1 to LD7 have the same maximum output (for example, about 100 mW for a multimode laser and about 50 mW for a single mode laser). The oscillation wavelength of the semiconductor laser LD is determined as follows.

  That is, since a single exposure head 166 is provided with a plurality of laser modules 64, and each laser module 64 is provided with a plurality of semiconductor lasers LD, the single exposure head 166 serves as a laser light source. A large number of semiconductor lasers LD are provided (the number of laser modules 64 provided in a single exposure head 166 is 14, and the number of semiconductor lasers LD provided in each laser module 64 is seven. If there is, the total number of semiconductor lasers LD provided in the single exposure head 166 is 98), but in this embodiment, all the semiconductor lasers LD provided in the single exposure head 166 The oscillation wavelength is determined to be approximately uniformly distributed within a wavelength range of 400 to 410 nm (405 ± 5 nm).

  As shown in FIGS. 17 and 18, the above combined laser light source is housed in a box-shaped package 40 having an upper opening together with other optical elements. The package 40 includes a package lid 41 created so as to close the opening thereof, and is formed by introducing a sealing gas after the deaeration process and closing the opening of the package 40 with the package lid 41. The combined laser light source is hermetically sealed in a closed space (sealed space). A base plate 42 is fixed to the bottom surface of the package 40, and the heat block 10, a condensing lens holder 45 that holds the condensing lens 20, and the multimode optical fiber 30 are disposed on the top surface of the base plate 42. A fiber holder 46 that holds the incident end is attached. The exit end of the multimode optical fiber 30 is drawn out of the package from an opening formed in the wall surface of the package 40.

  A collimator lens holder 44 is attached to the side surface of the heat block 10, and the collimator lenses 11 to 17 are held on the collimator lens holder 44. An opening is formed in the lateral wall surface of the package 40, and wiring 47 for supplying a drive current to the semiconductor lasers LD1 to LD7 is drawn out of the package through the opening. In FIG. 18, in order to avoid complication of the drawing, only the reference numeral of the semiconductor laser LD7 among the plurality of semiconductor lasers is shown, and only the reference numeral of the collimator lens 17 is shown among the plurality of collimator lenses.

  As shown in FIG. 19, each of the collimator lenses 11 to 17 is formed in a shape in which a region including the optical axis of a circular lens having an aspherical surface is cut out in a parallel plane. This elongated collimator lens can be formed, for example, by molding resin or optical glass. The collimator lenses 11 to 17 are closely arranged in the arrangement direction of the light emitting points so that the length direction is orthogonal to the arrangement direction of the light emitting points of the semiconductor lasers LD1 to LD7 (left and right direction in FIG. 19). On the other hand, as the semiconductor lasers LD1 to LD7, lasers having an active layer with an emission width of 2 μm and emitting laser beams B1 to B7 whose divergence angles in a direction parallel to the active layer and a direction perpendicular to the active layer are 10 ° and 30 °, respectively. Is used. These semiconductor lasers LD1 to LD7 are arranged so that the light emitting points are arranged in a line in a direction parallel to the active layer.

  Therefore, in the laser beams B1 to B7 emitted from the respective light emitting points, the direction in which the divergence angle is large coincides with the length direction and the divergence angle is small with respect to the elongated collimator lenses 11 to 17 as described above. Incident light is incident in a state where the direction coincides with the width direction (direction perpendicular to the length direction). The condensing lens 20 has a flat shape in which a region including the optical axis of a circular lens having an aspherical surface is cut out in a parallel plane, and the longitudinal direction of the flat shape is an arrangement of the collimator lenses 11 to 17. It arrange | positions along a direction, ie, a horizontal direction. The laser beams B <b> 1 to B <b> 7 that have passed through the collimator lenses 11 to 17 are collected by the condenser lens 20 and are incident on the incident end portions of the multimode optical fiber 30.

  As shown in FIG. 20, the image exposure apparatus 100 includes an overall control unit 300 that controls the operation of the entire image exposure apparatus 100, and a modulation circuit 301 is connected to the overall control unit 300. Is connected to a controller 302 for controlling the DMD 50. Further, an LD driving circuit 303 that drives the laser module 64 and a stage driving device 304 that drives the moving stage 152 are connected to the overall control unit 300.

[Operation of image exposure apparatus]
Next, the operation of the image exposure apparatus 100 will be described as an operation of the present embodiment. When exposing and recording an image such as a wiring pattern on the recording medium 150, the overall control unit 300 applies the semiconductor lasers LD 1 to LD 7 provided in each laser module 64 of each exposure head 166 of the scanner 162 via the LD drive circuit 303. Each emits light. As a result, the laser beams B1, B2, B3, B4, B5, B6, and B7 are respectively emitted as divergent light from the semiconductor lasers LD1 to LD7 provided in each laser module 64 of each exposure head 166, and these lasers are emitted. The lights B1 to B7 are converted into parallel lights by the corresponding collimator lenses 11 to 17, respectively. The collimated laser beams B <b> 1 to B <b> 7 are collected by the condenser lens 20 and converge on the incident end face of the core 30 a of the multimode optical fiber 30.

  In the present embodiment, a condensing optical system is configured by the collimator lenses 11 to 17 and the condensing lens 20, and a combining optical system is configured by the condensing optical system and the multimode optical fiber 30. The laser beams B <b> 1 to B <b> 7 collected by the lens 20 are incident on the core 30 a of the multimode optical fiber 30, propagate through the optical fiber, and are combined into one laser beam B to be output from the multimode optical fiber 30. The light is emitted from the optical fiber 31 coupled to the emission end. In each laser module 64, for example, when the coupling efficiency of the laser beams B1 to B7 to the multimode optical fiber 30 is 0.9 and each output of the semiconductor lasers LD1 to LD7 is 50 mW, the individual laser modules 64 ( A combined laser beam B having an output of 315 mW (= 50 mW × 0.9 × 7) can be obtained from each of the optical fibers 31 arranged in an array. Accordingly, the entire 14 multi-mode optical fibers 31 can obtain a laser beam B with an output of 4.4 W (= 0.315 W × 14).

  In addition, when exposing and recording an image such as a wiring pattern on the recording medium 150, image data (rendering raster data) representing an image to be exposed and recorded is input from the modulation circuit 301 to the controller 302, and the input image data is the controller. 302 is temporarily stored in a frame memory built in 302. This image data is data representing the density of each pixel constituting the image by binary values (whether or not dots are recorded). Further, during exposure recording of an image on the recording medium 150, the moving stage 152 that attracts the recording medium 150 to the surface is moved at a constant speed from the upstream side to the downstream side of the gate 160 along the guide 158 by the stage driving device 304. Is done.

  When the leading end of the recording medium 150 is detected by the sensor 164 attached to the gate 160 when the moving stage 152 passes directly below the gate 160, the image data stored in the frame memory of the controller 302 is the data of the controller 302. A plurality of lines are sequentially read out by the processing unit, and the data processing unit generates a control signal for each exposure head 166 based on the read image data. Further, the mirror drive control unit of the controller 302 controls the micromirrors of the DMD 50 to be switched on or off for each exposure head 166 based on the control signal generated by the data processing unit.

  When each of the exposure heads 166 irradiates the DMD 50 with the laser light B from the fiber array light source 66, the laser light reflected by the on-state micromirrors of the DMD 50 passes through the lens systems 54 and 58. Then, an image is formed on the recording medium 150. As a result, the laser light emitted from the fiber array light source 66 is subjected to on / off modulation for each pixel, and the recording medium 150 has a pixel unit (exposure) that is substantially the same as the number of pixels used by the DMD 50 (the number of micromirrors that are on / off controlled). It is exposed in area 168). Further, by moving the recording medium 150 together with the moving stage 152 at a constant speed, sub-scanning is performed with respect to the scanner 162 in which the recording medium 150 moves in a direction opposite to the stage moving direction. A strip-shaped exposed area 170 corresponding to the exposure head 166 is formed, and an image is exposed and recorded on the recording medium 150.

  Here, the exposure recording of the image on the recording medium 150 is performed when the laser light irradiated on the recording medium 150 passes through the light transmission layer 110 of the resist film 106 and reaches the photosensitive layer 108. However, since the thickness of the light transmission layer 110 of the resist film 106 in each part of the recording medium 150 varies within the range of manufacturing tolerances, the resonance frequency of the light transmission layer 110 is also different in each part of the recording medium 150. Assuming that the laser light applied to the recording medium 150 is a single-wavelength laser light, the amount of laser light that passes through the light transmission layer 110 and reaches the photosensitive layer 108 (light transmission layer transmission light amount) is recorded. Variations in the amount of light transmitted through the light transmission layer appear as uneven sensitivity of the photosensitive layer 108 in each part of the recording medium 150, and the exposure recording is performed on the recording medium 150 accordingly. The width of each line in the wiring pattern varies at each portion of the recording medium 150. In particular, since the recording medium 150 has the gloss of the light transmission layer 110, the amplitude of the laser light transmitted through the light transmission layer 110 is increased accordingly, and the resonance frequency of the light transmission layer 110 is the same as that of the recording medium 150. The difference in each part appears more prominently as variations in the amount of light transmitted through the light transmission layer in each part of the recording medium 150.

  In contrast, in the image exposure apparatus 100 according to the present embodiment, as described above, a single exposure head 166 is provided with a large number of semiconductor lasers LD as laser light sources. The oscillation wavelengths of all the provided semiconductor lasers LD are determined so as to be approximately uniformly distributed within a wavelength range of 400 to 410 nm (405 ± 5 nm). As is apparent from FIG. 1, the above wavelength range of 400 to 410 nm is wider than the resonance minimum wavelength range of the light transmission layer 110 (PET film) having a nominal film thickness of 13 μm (actual film thickness is 13.15 μm). (Details are more than 4 times the minimum resonance wavelength range) and wider than the minimum resonance wavelength range of the light transmission layer 110 (PET film) having a nominal film thickness of 18 μm (actual film thickness is 18.6 μm). Is at least four times the minimum resonance wavelength range).

  The laser light emitted from a large number of semiconductor lasers LD provided in the single exposure head 166 has the same multimode in units of a plurality of semiconductor lasers LD provided in the same laser module 64. After condensing, combining and propagating to the optical fiber 30, all of the light is combined by the lens system 67, so that the intensity in the beam cross-section is made uniform close to parallel light, and each of the wavelengths within the above wavelength range is also obtained. A laser beam having a wavelength is irradiated onto the DMD 50 as a synthesized laser beam. After being modulated by the DMD 50, an area corresponding to the exposure head 166 in the recording medium 150 is irradiated as an exposure laser beam.

  As a result, among the parts on the recording medium 150, the laser light of other wavelengths included in the exposure laser light in the part where the light transmission layer transmitted light amount of the laser light of the specific wavelength included in the exposure laser light shows the minimum value. The light transmission layer transmitted light amount of the above shows a value larger than the minimum value, a decrease in the light transmission layer transmitted light amount as the entire exposure laser light in the portion is suppressed, and among the portions on the recording medium 150, Even in the portion where the light transmission layer transmission light amount of the laser light of the specific wavelength included in the exposure laser light shows the maximum value, the light transmission layer transmission light amount of the laser light of other wavelengths included in the exposure laser light is smaller than the maximum value. By indicating the value, an increase in the amount of light transmitted through the light transmission layer as the entire exposure laser beam in the portion is suppressed. Therefore, the variation in the amount of light transmitted through the light transmission layer of the entire exposure laser beam in each part on the recording medium 150 can be reduced, and the apparent sensitivity unevenness of the photosensitive layer 108 in each part of the recording medium 150 can be suppressed. As a result, it is possible to prevent the widths of individual lines in the wiring pattern exposed and recorded on the recording medium 150 from varying in each part of the recording medium 150.

  Even when the wavelength of the laser beam emitted from each semiconductor laser LD of the exposure head 166 changes due to a change in the internal temperature of the exposure head 166 (ambient temperature of the semiconductor laser LD) or the like, In the portion, laser light whose light transmission layer transmission light amount decreases in the exposure laser light than before the wavelength change is generated, while laser light whose light transmission layer transmission light amount increases in the exposure laser light than before the wavelength change. As a result, fluctuations in the amount of light transmitted through the light transmission layer as the entire exposure laser beam at each portion on the recording medium 150 are suppressed. As a result, it is possible to suppress changes in the apparent sensitivity of the photosensitive layer 108 in each part of the recording medium 150 due to fluctuations in the wavelength of the laser light accompanying fluctuations in the ambient temperature of the semiconductor laser LD. The change of the width of each line in the wiring pattern exposed and recorded in 150 can be suppressed. Therefore, the variation in the thickness of the light transmission layer 110 in each part of the recording medium 150 and the variation in the wavelength of the laser light due to the variation in the ambient temperature of the semiconductor laser LD cause the image quality of the image to be exposed and recorded on the recording medium 150. An adverse effect can be avoided, and an image can be exposed and recorded on the recording medium 150 with high image quality and high definition.

  In the above, by determining the oscillation wavelengths of all the semiconductor lasers LD provided in the single exposure head 166 so as to be approximately uniformly distributed within the wavelength range of 400 to 410 nm (405 ± 5 nm), The oscillation wavelength of the semiconductor laser LD irradiated to the recording medium 150 by combining the emitted laser light is changed to the light transmission layer 110 of the recording medium 150 (specifically, the nominal film thickness is 13 μm or 18 μm (the actual film thickness is 13.15 μm). In addition, although an example in which the PET film is 18.6 μm) distributed uniformly in a wavelength range of four times or more of the minimum resonance wavelength range has been described, the present invention is not limited to this, and the emitted laser beam The oscillation wavelength of the semiconductor laser LD irradiated to the recording medium 150 after being combined with each other may be distributed within a wavelength range that is twice or more the minimum resonance wavelength range of the light transmission layer 110 of the recording medium 150. Light transmission through medium 150 The layer 110 may be distributed within a wavelength range that is equal to or greater than the resonance minimum wavelength range. In this case, the effect of suppressing image quality deterioration due to uneven sensitivity of the recording medium or sensitivity change can be obtained.

  Further, in the above description, the oscillation wavelength of the semiconductor laser LD irradiated with the recording medium 150 by combining the emitted laser light is approximately “uniform” within a wavelength range equal to or greater than the resonance minimum wavelength range of the light transmission layer 110 of the recording medium 150. However, the present invention is not limited to this, and it is desirable to distribute the oscillation wavelength of the laser light source approximately “uniformly” within the above wavelength range. Even if the oscillation wavelength is simply distributed within the above wavelength range (even if there is some deviation in the oscillation wavelength distribution within the above wavelength range), the recording medium is irradiated with laser light of a single wavelength In comparison, it is possible to obtain an effect of suppressing image quality deterioration due to uneven sensitivity of the recording medium and sensitivity change.

  Further, in the above description, a configuration in which laser beams emitted from a large number of semiconductor lasers LD are combined and applied to the recording medium 150 (the number of laser modules 64 provided in a single exposure head 166 is 14, When the number of semiconductor lasers LD provided in the laser module 64 is seven, the total number of semiconductor lasers LD provided in a single exposure head 166 (the emission laser light is combined to irradiate the recording medium 150). The total number of semiconductor lasers LD) is 98), but the number of laser beams to be combined (number of semiconductor lasers LD) is not limited to the above numerical values and may be plural. As described above with reference to FIG. 3, even if the number of laser light sources that multiplex the emitted laser light is two, the wavelength of the laser light emitted from each laser light source is within the resonance minimum wavelength range. If distributed, an effect of suppressing image quality deterioration due to uneven sensitivity of the recording medium or sensitivity change can be obtained as compared with the case where the recording medium is irradiated with laser light having a single wavelength.

  Further, in the above, as a recording medium according to the present invention, the resist film 106 provided with the light transmission layer 110 and only one photosensitive layer 108 is made of copper on the front and back surfaces of the base 104A made of glass epoxy. The recording medium 150 formed by being attached to the substrate 104 on which the conductive layer 104B is formed has been described as an example. However, the present invention is not limited to this, and for example, a configuration in which the resist film is attached to a glass substrate. It is also possible to apply the present invention to these recording media. This type of recording medium is used when manufacturing a color filter substrate used for a flat panel display or the like. The color filter substrate is formed by attaching a resist film to a glass substrate to form a recording medium, and exposing and recording a filter pattern of a specific color among R, G, and B on the recording medium, developing, etc. The process of forming the filter pattern of a specific color on the glass substrate through the process is repeated for each of R, G, and B colors. Further, the resist film is not limited to the configuration in which only one photosensitive layer is provided as shown in FIG. 5, and a plurality of photosensitive layers are laminated and a light transmission layer is provided on the laser light incident side. It is also possible to apply the present invention to a recording medium manufactured by using a resist film having the above structure and attaching the resist film to a substrate.

  In the above description, the recording medium according to the present invention has been described by way of example of a recording medium manufactured by sticking a resist film provided with a light transmission layer and a photosensitive layer to a substrate or the like. The present invention can be applied to any recording medium provided with a photosensitive layer and a light-transmitting layer on the photosensitive layer. The image recording apparatus according to the present invention is not limited to the configuration of the image exposure apparatus 100 described above, and may be any recording medium provided with a photosensitive layer and a light transmission layer on the upper layer. Needless to say, the present invention can be applied to an image recording apparatus having an arbitrary configuration for recording an image.

  Next, the results of analysis studies conducted by the present inventors in order to confirm the effects of the present invention will be described. In this analysis study, based on the result of an experiment in which the change in the light transmittance of the light transmission layer with respect to the change in the wavelength of the irradiation light was measured for a light transmission layer made of a PET film having a nominal film thickness of 13 μm (see FIG. 1). It was confirmed by calculation how the degree of fluctuation of the light transmittance of the light transmission layer accompanying the fluctuation of the wavelength range of the irradiation light changes depending on the width of the wavelength distribution range of the irradiation light. First, the results of the experiment are shown numerically in the following Table 1.

  The inventors of the present application based on the results of the above experiment, as a comparative example, a wavelength range of 401.0 to 402.2 (nm) (Comparative Example 1) set so that the width of the wavelength range is less than the resonance minimum wavelength range K, The wavelength range of 402.0 to 403.2 (nm) (Comparative Example 2), the wavelength range of 402.8 to 404.2 (nm) (Comparative Example 3), and the wavelength range of 403.8 to 405.2 (nm) (Comparative Example 4) Each of the average values of the light transmittances is calculated, and the difference between the maximum and minimum values of the light transmittances obtained for each wavelength range of Comparative Examples 1 to 4 and the total average value are calculated. The maximum value−minimum value / total average value ”was also calculated. In addition, the wavelength range of Comparative Examples 1-4 is each shown by the arrow in FIG.

  In addition, the inventors of the present application, as Example 1, have a wavelength range of 400.6 to 402.8 (nm) set so that the range of the wavelength range is not less than the resonance minimum wavelength range K and less than 2K (twice the resonance minimum wavelength range K). Wavelength range (Example 1-1), 401.6-403.8 (nm) wavelength range (Example 1-2), 402.4-404.8 (nm) wavelength range (Example 1-3), 403.4-405.6 (nm) For each wavelength range (Example 1-4), the average value of the light transmittance of the light transmission layer was calculated, and the average value of the light transmittance determined for each wavelength range of Examples 1-1 to 1-4 The difference between the maximum value and the minimum value and the total average value were calculated, and “(maximum value−minimum value) / total average value” was also calculated. The wavelength ranges of Examples 1-1 to 1-4 are indicated by arrows in FIG.

  In addition, the present inventors set 400.6 as Example 2 so that the width of the wavelength range is 2K (twice the minimum resonance wavelength range K) or more and less than 4K (four times the minimum resonance wavelength range K). ~ 404.8 (nm) wavelength range (Example 2-1), 401.6-405.6 (nm) wavelength range (Example 2-2), 402.4-406.6 (nm) wavelength range (Example 2-3), For the wavelength range of 403.4 to 407.6 (nm) (Example 2-4), the average value of the light transmittance of the light transmissive layer was calculated, and determined for each wavelength range of Examples 2-1 to 2-4. The difference between the maximum value and the minimum value of the average value of light transmittance and the total average value were calculated, respectively, and “(maximum value−minimum value) / total average value” was also calculated. The wavelength ranges of Examples 2-1 to 2-4 are indicated by arrows in FIG.

  Furthermore, the inventors of the present application, as Example 3, set a wavelength range of 400.6 to 408.6 (nm) in which the width of the wavelength range is set to 4K (4 times the minimum resonance wavelength range K) (Example 3- 1), a wavelength range of 401.6 to 409.6 (nm) (Example 3-2), a wavelength range of 402.4 to 410.6 (nm) (Example 3-3), a wavelength range of 403.4 to 411.6 (nm) (Example 3) -4) for each of the average value of the light transmittance of the light transmission layer, and the maximum and minimum values of the average value of the light transmittance obtained for each wavelength range of Examples 3-1 to 3-4 The difference and the total average value were calculated, respectively, and “(maximum value−minimum value) / total average value” was also calculated. The wavelength ranges of Examples 3-1 to 3-4 are indicated by arrows in FIG. The results of the above calculation are shown in Table 2 below.

  The (maximum value−minimum value) / total average value obtained in the above analysis study is the light transmittance of the light transmission layer when the wavelength range of the irradiation light irradiated to the light transmission layer is shifted with a temperature change or the like. It corresponds to the fluctuation rate. According to the results of the analysis study by the inventors of the present application, as shown in Table 2 above, the value of (maximum value−minimum value) / total average value increases as the wavelength range becomes wider as in Comparative Example → Example 3. Obviously it is getting smaller. From the above results, by combining laser beams emitted from a plurality of laser light sources and irradiating the combined laser beam on a recording medium including a photosensitive layer and a light transmission layer provided on the upper layer of the photosensitive layer. When recording an image on a recording medium, the wavelength distribution range of laser light emitted from a plurality of laser light sources is at least the minimum resonance wavelength range, preferably at least twice the minimum resonance wavelength range, more preferably the minimum resonance If the wavelength range is at least four times the wavelength range, the variation rate of the light transmittance of the light transmission layer when the wavelength distribution range of the laser light emitted from a plurality of laser light sources is shifted due to a temperature change or the like is suppressed to be small. It can be understood that fluctuations in the image quality of the recorded image can be suppressed.

It is a diagram which shows the wavelength-light transmittance characteristic of PET film. It is a schematic block diagram of a Fabry-Perot resonator. (A) is the minimum resonance wavelength range, and (B) is a diagram showing the wavelength-light transmittance characteristics of the light transmission layer for explaining the operation of the present invention, taking the case of using two laser light sources as an example. is there. It is a perspective view which shows the external appearance of the image exposure apparatus which concerns on this embodiment. It is the schematic which shows an example of a recording medium. It is a perspective view which shows the outline of the scanner of an image exposure apparatus. (A) is a plan view showing an exposed area formed on a recording medium, and (B) is a plan view showing an array of exposure areas of each exposure head. It is a perspective view which shows schematic structure of the optical system of an exposure head. It is a block diagram which shows the detail of the optical system of an exposure head. It is a perspective view which expands and shows DMD partially. FIG. 4A is a perspective view showing a DMD micromirror in an on state and FIG. FIG. 5A is a plan view showing the arrangement of exposure beams and scanning lines when DMD is not inclined, and FIG. It is a perspective view which shows a fiber array light source. It is a front view which shows the arrangement | sequence of the light emission point in the laser emission part of a fiber array light source. It is a side view which shows the coupling | bond part of a multimode optical fiber. It is a top view which shows the structure of a combined laser light source. It is a top view which shows the structure of a laser module. It is a side view which shows the structure of a laser module. It is a front view which shows the collimator lens of a laser module. It is a block diagram which shows schematic structure of the control system of an image exposure apparatus. It is explanatory drawing of the exposure area which shows the position of the exposure beam by DMD arranged in inclination. It is a diagram which shows the wavelength range of the comparative example in the analysis examination which this inventor etc. implemented. It is a diagram which shows the wavelength range of the Example in the analysis examination which this inventor etc. implemented.

Explanation of symbols

20 Condensing lenses 30, 31 Optical fiber 50 DMD
71 Condensing lens 72 Rod integrator 100 Image exposure apparatus 104 Substrate 106 Resist film 108 Photosensitive layer 110 Light transmitting layer 150 Recording medium 166 Exposure head LD Semiconductor laser

Claims (6)

By combining laser beams emitted from a plurality of laser light sources and irradiating the combined laser beam onto a recording medium including a photosensitive layer and a light transmission layer provided on the photosensitive layer, the recording medium An image recording apparatus for recording an image on
In the plurality of laser light sources, each of the emitted laser beams has a wavelength at which the light transmittance of the light transmissive layer is maximized, a light transmittance of the light transmissive layer is minimized, and the first An image recording apparatus characterized by being distributed so as to be distributed within a predetermined wavelength range equal to or greater than a resonance minimum wavelength range corresponding to a second wavelength having a minimum difference from the wavelength.   The image recording apparatus according to claim 1, wherein the predetermined wavelength range is a wavelength range that is twice or more the minimum resonance wavelength range.   The image recording apparatus according to claim 1, wherein the predetermined wavelength range is a wavelength range that is four times or more the minimum resonance wavelength range.   The plurality of laser light sources are characterized in that the wavelengths of the respective emitted laser beams are distributed within the predetermined wavelength range, and the light transmittances of the light transmission layers are different from each other. The image recording apparatus according to any one of claims 1 to 3.   The image recording apparatus includes a surface modulation element capable of independently controlling an emission direction of a light beam incident on a modulation surface provided with a plurality of modulation regions in units of partial light beams incident on the individual modulation regions. A laser beam that is a combination of laser beams emitted from the plurality of laser light sources is incident on the modulation surface of the surface modulation element, and is emitted in a predetermined direction by the surface modulation element of the incident laser beam. By guiding the plurality of partial laser light fluxes that are emitted from different modulation regions of the surface modulation element to each part on the recording medium so that at least a part thereof is overlapped. 4. The image recording apparatus according to claim 1, wherein the image recording apparatus is configured to record an image on the recording medium. An image for recording an image on the recording medium by combining and irradiating a recording medium including a photosensitive layer and a light transmission layer provided on the photosensitive layer with laser beams emitted from a plurality of laser light sources. A recording method,
The wavelength of the emitted laser light of each of the plurality of laser light sources includes a first wavelength at which the light transmittance of the light transmissive layer is maximized, a light transmittance of the light transmissive layer is at a minimum, and the first wavelength. The image recording method is characterized in that it is determined so as to be distributed within a predetermined wavelength range equal to or greater than the resonance minimum wavelength range corresponding to the second wavelength having the smallest difference.

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