Patent Application
20050018255
1. Field of the Invention
The present invention relates to an image-recording apparatus in which an image-recording head having a spatial light-modulation device is relatively moved with respect to an image-recording plane in a predetermined direction along the image-recording plane, where a great number of rows of image-recording elements are arranged in the spatial light-modulation device, a great number of image-recording elements are arranged along a line in each row of image-recording elements, and each image-recording element modulates incident light according to an inputted control signal. The present invention also relates to an image-recording method using the above image-recording apparatus.
2. Description of the Related Art
The following documents (1) and (2) disclose information related to the present invention.
In the DMD, when each micromirror is reset after image data (indicating “0” or “1”) is written in an SRAM, the micromirror tilts at a predetermined angle (corresponding to the ON or OFF state) according to the image data so that the direction to which light is reflected can be changed.
Incidentally, in order to complete the resetting operations of all of the micromirrors, it is necessary to transfer data to SRAMs, and change the tilt angles of the micromirrors after the transfer. Therefore, sometimes it takes a long time until the resetting operations are completed.
In order to overcome the above problem, the aforementioned document (1) discloses an image display system in which a spatial light modulator (SLM) is divided into reset groups, and the respective groups are connected to different reset lines. In this image display system, image data are loaded and images are displayed in the following manner. That is, after one of the reset groups is loaded with image data, the reset group, which is already loaded with the image data, can start and perform an image display operation while loading another reset group with other image data.
However, the manner disclosed in document (1) is applied to an image display system, and an application to an image-recording apparatus using, for example, lithography is not intended in document (1).
In addition, for example, document (2) proposes an exposure method which realizes exposure with little jaggies by relatively moving a photosensitive material with respect to a DMD so that areas irradiated with light beams reflected by adjacent micromirrors partially overlap each other. However, since the times necessary to update micromirrors cause a bottleneck, it is difficult to increase the scanning speed. In addition, it is also difficult to increase the resolution in the scanning direction while maintaining the scanning speed.
The present invention has been developed in view of the above circumstances.
A first object of the present invention is to provide an image-recording method which can reduce the time necessary to update a spatial light-modulation device.
A second object of the present invention is to provide an image-recording apparatus which can reduce the time necessary to update a spatial light-modulation device.
A third object of the present invention is to provide an image-recording method which can increase the resolution in a scanning direction while maintaining a scanning speed.
A fourth object of the present invention is to provide an image-recording apparatus which can increase the resolution in a scanning direction while maintaining a scanning speed.
(I) In order to accomplish the above first object, the first aspect of the present invention is provided. According to the first aspect of the present invention, there is provided an image-recording method for recording an image by relatively moving an image-recording head with respect to an image-recording plane in a predetermined direction along the image-recording plane, and realizing image formation on the image-recording plane with incident light modulated by a spatial light-modulation device, where the spatial light-modulation device is included in the image-recording head, and contains a plurality of rows of image-recording elements, and each of the image-recording elements modulates the incident light according to one of a plurality of control signals which is inputted to the image-recording element. The image-recording method according to the first aspect of the present invention is characterized in comprising the steps of: (a) determining a plurality of regions each containing at least one of the plurality of rows of image-recording elements by dividing the plurality of rows of image-recording elements; (b) outputting ones of the plurality of control signals to each of the plurality of regions on a region-by-region basis in succession; and (c) controlling ones of the image-recording elements in each of the plurality of regions on a region-by-region basis so that the ones of the image-recording elements start modulation of the incident light when an operation of inputting ones of the plurality of control signals into the region is completed.
In the above description of the first aspect of the present invention, the term “row of image-recording elements” means a group of image-recording elements arranged along a line in one of two array directions in a two-dimensional arrangement of the image-recording elements, where the one of the two array directions forms a greater angle with the scanning direction than the other of the two array directions. In addition, the term “modulate” means to exert an effect on incident light by actuating an image-recording element.
The image-recording method according to the first aspect of the present invention may also have one or any possible combination of the following additional features (i) to (xiv).
In the descriptions of the feature (vi), the term “multiple recording operations” means a process of recording an image by scanning an identical scanning line with a plurality of image-recording elements. When the number of the image-recording elements with which an identical scanning line is scanned is N, the term “multiple” means N-ple.
In the above description of the feature (viii), the direction along which the projected spots are arranged is one of two array directions in a two-dimensional arrangement of the image-recording elements, where the one of the two array directions forms a smaller angle with the scanning direction than the other of the two array directions.
In the descriptions of the features (ix) and (x), the “lines formed by ones of the image-recording elements” are each a group of image-recording elements arranged along a line in one of two array directions in a two-dimensional arrangement of the image-recording elements, where the one of the two array directions forms a smaller angle with the scanning direction than the other of the two array directions.
(II) In order to accomplish the aforementioned second object, the second aspect of the present invention is provided. According to the second aspect of the present invention, there is provided an image-recording apparatus comprising an image-recording head which forms on a image-recording plane an image of incident light modulated by a spatial light-modulation device, and is relatively movable with respect to the image-recording plane in a predetermined direction along the image-recording plane, where the spatial light-modulation device is included in the image-recording head, and contains a plurality of rows of image-recording elements, and each of the image-recording elements modulates the incident light according to one of a plurality of control signals which is inputted to the image-recording element. The image-recording apparatus according to the second aspect of the present invention is characterized in further comprising a control unit which outputs ones of the plurality of control signals to each of a plurality of regions of the spatial light-modulation device each containing at least one of the plurality of rows of image-recording elements, on a region-by-region basis in succession, and controls ones of the image-recording elements in each of the plurality of regions on a region-by-region basis so that the ones of the image-recording elements start modulation of the incident light when an operation of inputting ones of the plurality of control signals into the region is completed.
The image-recording apparatus according to the second aspect of the present invention may also have one or any possible combination of the aforementioned additional features (ii), (iii), (vi), (viii), (ix), and (x) and the following additional features (xv) to (xxiv).
(III) The present invention has the following advantages.
In the image-recording method according to the first aspects of the present invention and the image-recording apparatus according to the second aspects of the present invention, the plurality of rows of image-recording elements are divided into a plurality of regions, ones of the plurality of control signals are outputted to each of the plurality of regions on a region-by-region basis in succession, and ones of the image-recording elements in each of the plurality of regions are controlled on a region-by-region basis so that the ones of the image-recording elements start modulation of the incident light when an operation of inputting ones of the plurality of control signals into the region is completed. Therefore, it is possible to reset image-recording elements in one of the plurality of regions to which the transfer of control signals has already been completed, while transferring control signals to another of the plurality of regions. Thus, the time necessary to update the spatial light-modulation device can be reduced.
In addition, in the case where the control signals are outputted to only a portion of the image-recording elements in the above image-recording method and image-recording apparatus, the number of image-recording elements required to be controlled is reduced, and therefore the time necessary to update the spatial light-modulation device can be further reduced.
Further, the time necessary to update the spatial light-modulation device can be reduced more effectively when the number of the plurality of regions satisfies the relationship, d≧t/(t−u), where d is the number of the plurality of regions, t is a time until operations of inputting the plurality of control signals into all of the plurality of regions are completed, and u is a time necessary for ones of the image-recording elements in each of the plurality of regions to modulate the incident light.
Furthermore, when the number of at least one of the plurality of rows of image-recording elements constituting one of the plurality of regions is different from the number of at least one of the plurality of rows of image-recording elements constituting another of the plurality of regions, it is possible to reduce the number of the plurality of regions which are individually controlled, and therefore the control of the spatial light-modulation device can be simplified.
Moreover, when the spatial light-modulation device is arranged in the image-recording head in such a manner that the lines of image-recording elements in the spatial light-modulation device form with the scanning direction of the image-recording head a predetermined angle greater than zero, and the image is recorded with the image-recording head on the image-recording plane by performing multiple recording operations with a multiplicity of N (which is a natural number greater than one), and image-recording points recorded by using the spatial light-modulation device are shifted in the scanning direction by an amount which is predetermined for each of the plurality of regions, it is possible to increase the resolution in the scanning direction without decreasing the scanning speed, as explained later in detail.
An embodiment of the present invention will be described in detail below with reference to the attached drawings. Although numerical values are indicated in the following descriptions, the present invention is not limited to such numerical values.
Construction of Exposure System
The image-recording apparatus according to an embodiment of the present invention is an exposure system of a so-called flat-head type. As illustrated in
A U-shaped gate 160 is arranged at the center of the mount table 156 so as to straddle the movement path of the stage 152. Two ends of the U-shaped gate 160 are respectively fixed to side surfaces of the mount table 156. A scanner 162 is fixed to one side of the U-shaped gate 160, and a plurality of sensors 164 (e.g., two sensors) are fixed to the other side of the U-shaped gate 160, in such a manner that the scanner 162 and the sensors 164 are fixedly located above the path of the stage 152. The plurality of sensors 164 are provided for detecting front and rear edges of the photosensitive sheet 150. The scanner 162 and the sensors 164 are connected to a controller (not shown) which controls the scanner 162 and the sensors 164. As will be described later, the scanner 162 and the sensors 164 are controlled so that the exposure heads 166 perform exposure at predetermined timings.
As illustrated in
As illustrated in
In addition, as illustrated in
As illustrated in
In addition, the mirror-actuation control unit controls the tilt angles of reflection surfaces of the respective micromirrors in the DMD 50 constituting each exposure head 166mn based on the control signals generated by the data processing unit.
On the light-entrance side of the DMD 50, a fiber-array light source 66, a lens system 67, and a mirror 69 are arranged in this order. The fiber-array light source 66 comprises a laser emission unit in which emission-end portions (light-emission points) of optical fibers are arranged to form a row along a direction corresponding to the longer sides of the exposure areas 168. The lens system 67 corrects laser light outputted from the fiber-array light source 66 so that the corrected laser light condenses on the DMD. The mirror 69 reflects the laser light which has passed through the lens system 67, toward the DMD 50.
The lens system 67 comprises a first pair of combined lenses 71, a second pair of combined lenses 73, and a condensing lens 75. The first pair of combined lenses 71 collimates the laser light outputted from the fiber-array light source 66, and the second pair of combined lenses 73 corrects the distribution of the intensity of the collimated laser light so as to make the distribution uniform. The condensing lens 75 condenses the laser light corrected by the second pair of combined lenses 73 onto the DMD. In the correction of the distribution of the intensity of the collimated laser light, each light beam is widened when the light beam passes through a portion of the second pair of combined lenses 73 near to the optical axis of the second pair of combined lenses 73 in the direction along which the light-emission points are arranged, or narrowed when the light beam passes through a portion of the second pair of combined lenses 73 far from the optical axis of the second pair of combined lenses 73, and the widths of the light beams in the direction perpendicular to the direction along which the light-emission points are not changed, so that the distribution of the intensity of the laser light becomes uniform.
Further, lens systems 54 and 58 are arranged on the light-output side of the DMD 50 so that an image of the laser light reflected by the DMD 50 is formed on a scanning plane (exposure plane) 56, and the DMD 50 and the exposure plane 56 are optically conjugate to each other.
As illustrated in
When a digital signal is written in an SRAM cell 60 in the DMD 50, a micromirror supported by a post tilts around a diagonal of the micromirror ±α degrees (e.g., 10 degrees) with respect to a substrate on which the DMD 50 is formed.
Actuation of DMD
In the present embodiment, the controller controls the actuation of the DMD so as to use only a portion of the micromirrors 62, e.g., only 192 rows located in a central area of the micromirrors 62 having 768 rows arranged in the scanning direction, as illustrated in
Since, generally, the data processing speed of the DMD 50 is limited, the time necessary to update pixels in each row is determined according to the number of used pixels. In order to update the micromirrors, both of the time for transferring digital signals to the SRAM cells and writing the digital signals in the SRAM cells and the time for resetting the respective micromirrors are necessary. Therefore, if all of the micromirrors 62 are used, the time for transferring the digital signals to all of the SRAM cells 60 is necessary. On the other hand, according to the present embodiment, the DMD 50 is partially actuated, i.e., only a portion of the micromirror rows is used. Therefore, the time necessary to transfer digital signals to the SRAM cells is reduced in correspondence with the reduction in the number of the used micromirrors.
Preferably, the number of the used micromirror rows is not less than 10 and not greater than 240. In this embodiment, it is assumed that the size of a micromirror corresponding to each pixel is 15×15 micrometers. Therefore, the preferable size of the used area of the DMD 50 corresponding to the above preferable range of the number of the used micromirror rows is from 12 mm×150 micrometers to 12 mm×3.6 mm.
When the number of the used micromirror rows corresponds to the above preferable size, the lens system 67 can almost completely collimate the laser light emitted from the fiber-array light source 66 so that the collimated laser light enters the DMD 50 as indicated in
In order to partially actuate the DMD 50, the used area of the DMD 50 may be micromirror rows located in either a central or near-edge area in the scanning direction. In addition, the used area of the DMD 50 may be changed as circumstances demand. For example, when a defect occurs in a portion of the micromirrors 62, one or more micromirror rows which contain no defective micromirror may be used instead of the portion having the defect. Further, an effect equivalent to that of the above partial actuation can be achieved by using a DMD which is produced so as to contain only micromirror rows corresponding to the aforementioned preferable size.
Furthermore, according to the present embodiment, as illustrated in
In the operations of
On the other hand, in the case where the divided reset actuation is performed according to the present embodiment, as indicated in
As described above, according to the present embodiment, both of the partial actuation and the divided reset actuation are performed. Therefore, compared with the case where only one of these method is performed, the time necessary to update the pixels of the DMD 50 is remarkably reduced. Table 1 shows examples of the times necessary to update the pixels of the DMD 50 in the four cases which are determined based on whether or not the partial actuation is performed and whether or not the divided reset actuation is performed. In Table 1, the ratio of the time necessary to update the pixels in each case to the time necessary to update the pixels in the case where neither of the partial actuation and the divided reset actuation is performed is indicated in parentheses.
As indicated in Table 1, the time necessary to update the pixels can be reduced to about 83% when only the divided reset actuation is performed, and to about 38% when only the partial actuation is performed. On the other hand, according to the present embodiment, the time necessary to update the pixels can be reduced to about 20% due to a synergistic effect of the partial actuation and the divided reset actuation.
Although, in the example illustrated in
Generally, when the time necessary to transfer the digital signals to all of the regions 1 to 5 is indicated by t, and the time necessary to reset the micromirrors in each of the regions 1 to 5 is indicated by u, and the number of the regions 1 to 5 is indicated by d, the time necessary for completing updating of the pixels of all of the regions 1 to 5 (i.e., the modulation time) is equal to a greater one of t and t/d+u. For example, in the example illustrated in
However, in the example illustrated in
d≧t/(t−u),
where t>u. For example, since, in the example of
Incidentally, it is preferable that the time t1 to transfer a digital signal to the SRAM cells 60 is shorter than the modulation time t2 (the time t2 to update one pixel (one micromirror)), i.e., t1≦t2. When the scanning speed of the exposure heads 166 is indicated by v, and the distance (exposure pitch) in the scanning direction by which the photosensitive sheet 150 moves until a pixel is updated is indicated by r, the modulation time t2 of a pixel is r/v. In addition, when m rows out of M rows arranged in the scanning direction are used, and the transfer time necessary to transfer digital signals to all of the M rows is indicated by T, the time t1 necessary to transfer digital signals to the used rows of the SRAM cells 60 is T×(m/M). Therefore, it is preferable that T×(m/M)≦r/v, i.e., m≦Mr/vT. For example, when M=768, and v=80 mm/sec, and r=2 micrometers, and T=100 microseconds, Mr/vT=192. In the above examples, the number m of the used rows is determined so as to satisfy the above relationship. At this time, the transfer time is T×(m/M)=100×192/768 =25 microseconds.
Fiber-array Light Source
As illustrated in
Each multimode optical fiber 30 and each optical fiber 31 may be a step-index type, a graded-index type, or a composite-type optical fiber. For example, the multimode optical fibers 30 and the optical fibers 31 may be formed by using the step-index type optical fiber manufactured by Mitsubishi Cable Industries, Ltd.
Each of the above laser modules 64 is constituted by a combined-laser-light source (fiber light source) illustrated in
The GaN-based semiconductor lasers LD1 through LD7 have an identical oscillation wavelength and an identical maximum output power. For example, the oscillation wavelength is 405 nm, and the maximum output power is 100 mW in the case where the GaN-based semiconductor lasers LD1 through LD7 are multimode semiconductor lasers, and 30 mW in the case where the GaN-based semiconductor lasers LD1 through LD7 are single-mode semiconductor lasers. Further, the oscillation wavelength is not limited to 405 nm, and the GaN-based semiconductor lasers LD1 through LD7 may have any oscillation wavelength in the range of 350 to 450 nm.
As illustrated in
A base plate 42 is fixed on the inner bottom surface of the package 40. The aforementioned heat block 10, a condensing-lens holder 45 for holding the condensing lens 20, and a fiber holder. 46 for holding the light-entrance end of the multimode optical fiber 30 are fixed to the upper surface of the base plate 42. The light-emission end portion of the combined-laser-light source is led out of the package 40 through an opening formed in a wall of the package 40.
In addition, a collimator-lens holder 44 for holding the collimator lenses 11 through 17 is attached to a side wall of the heat block 10. Further, wirings 47 for supplying driving currents to the GaN-based semiconductor lasers LD1 through LD7 are led out of the package 40 through openings formed in a side wall of the package 40.
In
Each of the GaN-based semiconductor lasers LD1 to LD7 comprises an active layer having an emission width of 2 micrometers. For example, the spread angle of each of laser beams B1 through B7 emitted from the GaN-based semiconductor lasers LD1 to LD7 is 10 degrees in the direction parallel to the active layer and 30 degrees in the direction perpendicular to the active layer.
The GaN-based semiconductor lasers LD1 to LD7 are arranged so that the light-emission points of the GaN-based semiconductor lasers LD1 to LD7 are aligned along a line parallel to the active layers of the GaN-based semiconductor lasers LD1 to LD7. Therefore, the laser beams B1 through B7 emitted from the GaN-based semiconductor lasers LD1 to LD7 respectively enter the collimator lenses 11 through 17 so that the direction of the greater spread angle of each of the laser beams B1 through B7 coincides with the length direction of each of the collimator lenses 11 through 17, and the direction of the smaller spread angle of each of the laser beams B1 through B7 coincides with the width direction of each of the collimator lenses 11 through 17 (which is perpendicular to the length direction).
The condensing lens 20 has a shape which is obtained by cutting with parallel planes a round lens having an aspherical surface so as to leave an elongated portion containing the optical axis of the round lens. Thus, the condensing lens 20 is elongated in the (horizontal) direction along which the collimator lenses 11 through 17 are arranged, and has a small dimension in the direction perpendicular to the direction along which the collimator lenses 11 through 17 are arranged. For example, the condensing lens 20 has a focal length f2 of 23 mm and a numerical aperture (NA) of 0.2. The condensing lens 20 can be formed, for example, by molding from resin or glass.
Operations of Exposure System
The operations of the exposure system according to the present embodiment will be described below.
In each of the exposure heads 166 in the scanner 162, the laser beams B1 through B7 emitted from the GaN-based semiconductor lasers LD1 through LD7 in the fiber-array light source 66, which are divergent, are respectively collimated by the corresponding collimator lenses 11 through 17. Then, the collimated laser beams B1 through B7 are collected by the condensing lens 20, and converge on the light-entrance end face of the core 30a of the multimode optical fiber 30.
In this example, the collimator lenses 11 through 17 and the condensing lens 20 constitute an optical condensing system, and the optical condensing system and the multimode optical fiber 30 constitute an optical combining system. Thus, the laser beams B1 through B7 collected by the condensing lens 20 as above enter and propagate in the core 30a of the multimode optical fiber 30, in which the laser beams B1 through B7 are combined (optically multiplexed) into a single laser beam B. Then, the laser beam B is outputted from the multimode optical fiber 30, enters another optical fiber 31 coupled to the multimode optical fiber 30, and is outputted from the optical fiber 31.
As described before, in the laser emission end 68 of the fiber-array light source 66, a plurality of light-emission points are arranged along a line in the main scanning direction, and the intensity of the laser light emitted from each of the light-emission points is high. On the other hand, the conventional fiber light sources in each of which a light beam from a single semiconductor laser is merely coupled to a single optical fiber have low output power. Therefore, when the conventional fiber light sources are used in the exposure system, a great number of light sources are required to be used, and the optical fibers of the light sources are required to be arranged in a great number of rows. However, since the output power of the combined-laser-light source used in the present embodiment is high, it is possible to obtain desired output power even when the number of rows of the optical fibers arranged in the laser emission end of the combined-laser-light source is small (e.g., one) Image data representing an exposure pattern is inputted into the controller (not shown) connected to the DMD 50, and is temporarily stored in a frame memory provided in the controller. The image data represents the density of each pixel by a binary value indicating whether or not a dot is to be recorded.
The stage 152 which holds a photosensitive sheet 150 on its surface by suction is moved at a constant speed by the aforementioned driving device (not shown) along the guides 158 from the upstream side to the downstream side of the U-shaped gate 160. When the stage 152 passes under the U-shaped gate 160, and the front edge of the photosensitive sheet 150 is detected by the sensors 164 fixed to the U-shaped gate 160, the image data stored in the frame memory is successively read out in groups of a plurality of lines, and a control signal for each of the exposure heads 166 is generated by the aforementioned data processing unit based on the image data which is read out. Then, each of the micromirrors 62 in the DMD 50 in each of the exposure heads 166 is on-off controlled by the mirror-actuation control unit based on the control signal.
When the laser beams emitted from the fiber-array light source 66 is applied to the DMD 50, portions of the laser beams reflected by portions of the micromirrors which are in the ON state pass through the lens systems 54 and 58, and form an image on the exposure plane 56 of the photosensitive sheet 150.
As described above, the laser beams emitted from the fiber-array light source 66 are on-off controlled on a pixel-by-pixel basis, so that the photosensitive sheet 150 is exposed on a pixel-by-pixel basis, where the pixels of the DMD 50 almost correspond to the pixels exposed on the photosensitive sheet 150 (and realized by the exposure areas 168 ).
As described before, according to the present embodiment, both of the partial actuation and the divided reset actuation are used for actuation of the DMD 50. Therefore, compared with the case where only one of the partial actuation and the divided reset actuation is used, the time necessary to update pixels is remarkably reduced. Thus, high-speed exposure is enabled.
In addition, since the photosensitive sheet 150 is moved at a constant speed together with the photosensitive sheet 150, the photosensitive sheet 150 is scanned in the direction opposite to the direction in which the photosensitive sheet 150 is moved, and bandlike exposed areas 170 are formed in correspondence with the exposure heads 166, respectively.
When the scanning of the photosensitive sheet 150 by using the scanner 162 is completed, and the rear edge of the photosensitive sheet 150 is detected by the sensors 164, the driving device (not shown) moves the stage 152 back to its initial position along the guides 158, where the initial position is the most upstream position of the guides 158. Thereafter, the driving device moves the stage 152 again from upstream to downstream along the guides 158 at the constant speed for the next exposure operation.
Further, in the so-called multiple exposure systems, identical scanning lines are multiply exposed with light beams reflected by different micromirrors. When DMDs in the multiple exposure systems are actuated as in the present embodiment, the resolution in the scanning direction can be improved by the divided reset actuation.
Variations of Divided Reset Actuation
(i) In the above embodiment, the numbers of the micromirror arrays in the respective regions for the divided reset actuation are approximately identical. However, it is unnecessary to equalize the numbers of the micromirror arrays in the respective regions for the divided reset actuation. That is, it is possible to differentiate the number of micromirror arrays in at least one region from the numbers of micromirror arrays in the other regions. For example, in the case where only 240 micromirror arrays are used for partial actuation, and the time t necessary to transfer control signals to all of the regions for the divided reset actuation is 32 micrometers, and the time u necessary to reset micromirrors in each of the regions (the reset time of each region) is 18 micrometers, it is preferable that the number d of division is 3, 4, or 5 in consideration of the condition obtained by the following calculation.
d≧t/(t−u)=32/(32−18)=2.29
Therefore, in the case where d=3, for example, the numbers of micromirror arrays in the regions 1 through 3 may be respectively: 96, 96, and 48; or 96, 48, and 96; or 48, 96, and 96. In addition, in the case where d=4, for example, the numbers of micromirror arrays in the regions 1 through 4 may be respectively: 96, 48, 48, and 48; or 48, 96, 48, and 48; or 48, 48, 96, and 48; or 48, 48, 48, and 96. Further, in the case where d=5, the number of micromirror arrays in each of the regions 1 through 5 may be 48, as in the embodiment explained before.
Even when the numbers of micromirror arrays in the respective regions are different, it is possible to achieve a similar effect to the effect which is achieved when the numbers of micromirror arrays in the respective regions are identical. For example,
(ii) As illustrated in
Alternatively, instead of arranging the DMDs 50 in a rotated orientation, the micromirrors 62 per se may be slightly obliquely arranged with respect to the scanning direction as illustrated in
Since the divided reset actuation is performed in the present invention, it is possible to increase the resolution in the scanning direction without decreasing the scanning speed, by applying the present invention to the multiple exposure system. Specifically, when the DMDs 50 are arranged in an orientation slightly rotated from the scanning direction so that each scanning line is scanned with laser beams reflected by more than one micromirror, and the divided reset actuation is performed, it is possible to produce a group of exposed spots at a different position for each of the regions for the divided reset actuation. Therefore, the resolution in the scanning direction can be increased without decreasing the scanning direction.
In order to clarify the effect of increasing the resolution, first, the exposed areas in the case where multiple exposure is simply performed without performing the divided reset actuation is explained.
When triple exposure is performed without the divided reset actuation, as illustrated in
On the other hand,
In addition, in the case where the divided reset actuation is performed, the positions of the exposed spots (dots) can be adjusted by controlling the output timings of the control signals supplied to the respective regions according to the movement of the photosensitive sheet 150. For example, the positions of the exposed spots (dots) can be dispersed. Thus, it is possible to obtain an exposed image having a desired resolution by controlling the output timings of the control signals supplied to the respective regions so that spots (dots) exposed on the photosensitive sheet 150 are desirably located. That is, when the above control is realized, it is possible to increase the resolution without decreasing the moving speed of the photosensitive sheet 150.
Further, in the case where the divided reset actuation is performed, it is preferable that the control signals are generated in consideration of the movement of the photosensitive sheet 150 and the differences in the input timings of the control signals to the respective regions. That is, it is preferable to generate image-recording data for each dot based on image data representing the image to be exposed, in consideration of the movement of the photosensitive sheet 150 and the differences in the input timings of the control signals to the respective regions, and reflect the image-recording data in the control signals to be outputted to the spatial light-modulation device.
Specifically, in the example of
Other Variations and Additional Matters
(i) In the above examples, the exposure heads comprise a DMD as a spatial light-modulation device. The DMD is a reflection-type, spatial light-modulation device. Alternatively, it is possible to use a transmission-type, spatial light-modulation device. For example, the spatial light-modulation devices may be: MEMS (micro electromechanical systems) type SLMs (spatial light modulators); optical elements which modulate transmitted light by the electro-optical effect, e.g., PLZT (lanthanum-doped lead zirconate titanate) elements; or liquid crystal shutter arrays, e.g., FLC (ferroelectric liquid crystal) shutters; where Microsystems in which micro-size, sensors, actuators, and control circuits are integrated by using the micromachining technology based on the IC manufacturing processes are collectively called MEMS, and the MEMS type SLMs are spatial light-modulation devices which are actuated by electromechanical operations utilizing electostatic forces.
Further, it is possible to form a spatial light-modulation device by two-dimensionally arranging GLVs (grating light valves).
When the GLVs or the transmission-type, spatial light-modulation devices such as the liquid crystal shutter arrays are used, it is possible to use a lamp or the like as the light source.
(ii) In the present embodiment, the fiber-array light source comprising arrayed combined-laser-light sources is used as a laser-light source. However, other types of light sources can be used. For example, it is possible to use a fiber-array light source in which a plurality of fiber light sources are arrayed, and each of the fiber light sources is constituted by a single semiconductor laser having a single light-emission point and a single optical fiber outputting laser light which is emitted from the semiconductor laser and enters the optical fiber.
Further, it is possible to use a light source in which a plurality of light-emission points are two-dimensionally arranged. For example, the plurality of light-emission points may be a plurality of laser diodes or a plurality of organic electroluminescent elements. In this case, when the plurality of light-emission points are respectively arranged in correspondence with pixels, the aforementioned construction for spatial light modulation can be dispensed with.
(iii) In the above examples, the entire area of the photosensitive sheet 150 is scanned with the scanner 162 in the X-direction in a single scanning cycle, as illustrated in
Alternatively, it is possible to scan the entire photosensitive sheet 150 in a plurality of scanning cycles, as illustrated in
(iv) Although the exposure system in the present embodiment is a so-called flat-head type exposure system, the present invention can also be applied to so-called outer-drum type exposure systems, which comprise a drum around which a photosensitive material is placed.
(v) For example, the exposure system according to the present embodiment can be used for formation of color filters in manufacturing processes of liquid-crystal display devices (LCDs), and exposure of dry film resists (DFRs) in manufacturing processes of printed wiring boards (PWBs), thin-film transistors (TFTs), or plasma display panels (PDPs).
(vi) In the exposure system according to the present embodiment, either of the photon-mode photosensitive material and the heat-mode photosensitive material can be used. In the photon-mode photosensitive material, information is recorded directly by exposure to light. In the heat-mode photosensitive material, information is recorded by heat generated by exposure to light. When the photon-mode photosensitive material is used, GaN-based semiconductor lasers or wavelength-conversion solid-state lasers can be used as the laser devices. When the heat-mode photosensitive material is used, AlGaAs-based semiconductor lasers (infrared lasers) or solid-state lasers can be used as the laser devices.
(vii) The divided reset actuation according to the present invention can also be applied to image-recording control in printers such as inkjet printers. For example, image-recording dots produced by squirts of ink can be controlled in a similar manner to the present invention. That is, the present invention can also be applied to image-recording control in printers by substituting the image-recording elements in the present invention by the elements which produce image-recording dots by squirts of ink or the like.
(viii) In addition, all of the contents of the Japanese patent applications Nos. 2003-277613 and 2004-205415 are incorporated into this specification by reference.
| Number | Date | Country | Kind |
|---|---|---|---|
| 277613/2003 | Jul 2003 | JP | national |
