JP3910317B2 - Image recording method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image recording method and apparatus using a two-dimensional spatial light modulation element, and more particularly, to an image recording method and a method for performing multiple recording of one recording pixel by a plurality of pixels of a two-dimensional spatial light modulation element. It relates to the device.
[0002]
[Prior art]
Conventionally, various image recording apparatuses that record an image on a photosensitive recording medium using a light modulation element have been provided. They use a one-dimensional light modulation element typified by an LED array to expose a photosensitive recording medium in a line, and at the same time, place the one-dimensional light modulation element and the photosensitive recording medium in a direction substantially perpendicular to the line. It is roughly divided into a type that performs sub-scanning by moving it and a type that performs so-called surface exposure by projecting an image by a two-dimensional spatial light modulator such as a liquid crystal panel onto a photosensitive recording medium.
[0003]
For example, Japanese Patent Application Laid-Open No. 7-223337 discloses an example of the former type of image recording apparatus, and Japanese Patent Application Laid-Open No. 8-334838 discloses an example of the latter type of image recording apparatus.
[0004]
[Problems to be solved by the invention]
By the way, in the conventional image recording apparatus using the above-described one-dimensional light modulation element, if unevenness exists in the characteristics of the pixels of the light modulation element, stripes running in the sub-scanning direction appear in the recorded image, and the image quality is impaired. The problem is recognized.
[0005]
On the other hand, in a conventional image recording apparatus using a two-dimensional spatial light modulation element, if the number of pixels of the spatial light modulation element is small, a pixel of a recorded image (hereinafter referred to as “a pixel of the spatial light modulation element” Naturally, the number of “recording pixels” is also reduced, and it is recognized that it is difficult to record a high-definition, high-quality image.
[0006]
Therefore, in order to record a high-definition and high-quality image using a two-dimensional spatial light modulator having a relatively small number of pixels, the two-dimensional spatial light modulator and the photosensitive recording medium There is also known a multiple exposure method by so-called pixel shift, in which new recording pixels are written in such a manner that the recording pixels are relatively shifted and the gaps between recorded recording pixels are filled. However, in order to execute this, a mechanism for pixel shifting is required, which complicates the image recording apparatus.
[0007]
The present invention has been made in view of the above circumstances, and can record a high-definition and high-quality image even when a two-dimensional spatial light modulator having a relatively small number of pixels is used, and runs in the sub-scanning direction. An object of the present invention is to provide an image recording method and apparatus capable of preventing the occurrence of uneven stripes.
[0008]
[Means for Solving the Problems]
The image recording apparatus according to the present invention performs sub-scanning by relatively moving the two-dimensional spatial light modulation element and the photosensitive recording medium in a direction inclined with respect to the pixel arrangement direction of the two-dimensional spatial light modulation element. In addition to increasing the number of recording pixels in the scanning direction (direction substantially perpendicular to the sub-scanning direction), each of the recording pixels arranged in the main scanning direction is recorded by a plurality of pixels to suppress the occurrence of unevenness.
[0009]
That is, more specifically, the image recording apparatus of the present invention includes:
A light source that emits recording light;
A two-dimensional spatial light modulation element that has a plurality of pixels arranged two-dimensionally in a state of being adjacent to each other in one direction and another direction orthogonal thereto, and modulates the recording light;
Each pixel of the two-dimensional spatial light modulator is placed in a state in which pixels are adjacent to each other without any gap in one pixel arrangement direction to form a pixel row, and between the pixels in another pixel arrangement direction. An optical system that forms an image in a state where a void is generated;
A sub-scanning unit that disposes a photosensitive recording medium at an image forming position of the optical system, and that sub-scans the photosensitive recording medium in a direction that is inclined with respect to the pixel row and crosses the other pixel arrangement direction;
The two-dimensional spatial light modulation element is composed of k pixel groups (k ≧ 2) each composed of j pixels (j ≧ 2) adjacent to each other in one of the pixel columns, and the sub-scanning movement is performed. And control means for driving to record k pixels arranged in the main scanning direction substantially orthogonal to the direction.
[0010]
The above optical system includes, for example, an anamorphic optical system that has a refractive power only in the one pixel arrangement direction and reduces the entire pixel row, and a refractive power only in the other pixel arrangement direction. And a cylindrical lens array optical system that individually reduces the plurality of pixels.
[0011]
In the image recording apparatus of the present invention, preferably, so as to compensate for a shift in recording time between the respective pixel columns due to the image of the pixel columns of the two-dimensional spatial light modulator being inclined on the photosensitive recording medium, A delay is set in the driving time between the pixel columns of the two-dimensional spatial light modulator.
[0012]
On the other hand, in the image recording apparatus of the present invention, preferably, color filters of different colors are attached to the plurality of divided regions of the two-dimensional spatial light modulator, and the same portion of the color photosensitive recording medium is recorded by the recording light passing through each color filter. Can be recorded on the photosensitive recording medium.
[0013]
In addition, a plurality of light sources that emit light of different wavelengths are used as the light source, and the plurality of light sources are driven in a time-sharing manner in synchronization with the sub-scan feed of the color photosensitive recording medium so that a color image is displayed on the photosensitive recording medium. It may be possible to record.
[0014]
Furthermore, in the image recording apparatus of the present invention, preferably, pixels that are not used for image recording are set between the pixel groups.
[0015]
On the other hand, in the plurality of pixels in the pixel group, when the required exposure amount is minimum, one pixel at the center of the pixel group is in a light passing state, and gradually increases toward the end of the pixel group as the required exposure amount increases. It is desirable that the pixel is driven so as to be in a light passing state.
[0016]
The image recording method according to the present invention also provides a recording light by a two-dimensional spatial light modulation element having a plurality of pixels arranged two-dimensionally in a state of being adjacent to each other in one direction and another direction orthogonal thereto. In the following step a), each pixel of the two-dimensional spatial light modulator is adjacent to each other without any gap in one pixel arrangement direction. Forming a pixel row, forming a gap between the pixels in another pixel arrangement direction, and forming an image of the two-dimensional spatial light modulator on the photosensitive recording medium;
b) k pixels arranged in one direction of the photosensitive recording medium by k pixel groups (k ≧ 2) each composed of j pixels (j ≧ 2) adjacent to each other in one of the pixel columns. Record,
c) The photosensitive recording medium is recorded by sub-scanning movement in a direction inclined with respect to the pixel row.
It is characterized by including.
[0017]
【The invention's effect】
FIG. 5 shows the relationship between the pixel row 12b imaged by the optical system and the photosensitive recording medium 17. Here, as an example, one pixel column 12b is composed of 20 pixels, j = 5 pixels each form one pixel group, and k = 4 pixels exist in one pixel column. To do.
[0018]
If the two-dimensional spatial light modulator is arranged in a state where the extending direction of the pixel row 12b and the sub-scanning direction coincide with each other, the number of recording pixels in the main scanning direction is equal to the number of pixels in the main scanning direction of the two-dimensional spatial light modulator ( It is equal to 5 in the figure. On the other hand, when the two-dimensional spatial light modulator is tilted as shown in FIG. 5, one pixel is recorded by k = 4 pixel groups, so that four pixels can be recorded per pixel column. It becomes. Therefore, in the entire main scanning direction, four times the number of pixels in the main scanning direction (20 pixels according to the example in the figure) can be recorded, and a high-definition and high-quality image can be recorded.
[0019]
In addition, since one recording pixel is recorded by j = 5 pixels, even if characteristic unevenness exists in one or two of the five pixels, it is alleviated by other pixels, It is possible to prevent stripes running in the sub-scanning direction from appearing in the recorded image.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the overall configuration of an image recording apparatus according to an embodiment of the present invention. This image recording apparatus includes a light source 11 that emits recording light 10 and a plurality of pixels 12 that are two-dimensionally arranged to modulate the recording light 10, for example, a transmissive two-dimensional spatial light composed of a liquid crystal panel or the like. It has a modulation element 13, an optical system 16 comprising a pixel deformation optical system 14 and an imaging lens 15, and a sub-scanning means 18 for moving a long photosensitive recording medium 17 in the sub-scanning direction in the direction of the arrow y in the figure. .
[0021]
The driving of the light source 11, the two-dimensional spatial light modulator 13 and the sub-scanning means 18 is controlled by the light source controller 20, the spatial light modulator controller 21 and the sub-scan feed system controller 22, respectively. The light source control unit 20, the spatial light modulation element control unit 21, and the sub-scan feed system control unit 22 are controlled by the overall control unit 23.
[0022]
Next, the pixel deformation optical system 14 will be described in detail. FIGS. 2 and 3 show the planar shape and side surface shape of the optical system 16 comprising the pixel deformation optical system 14 and the imaging lens 15, respectively. 1 to 3 and FIG. 4 to be described later, the two-dimensional spatial light modulator 13 is shown as having 5 × 5 = 20 pixels 12 for convenience, but the actual number of pixels is larger than that. There are many.
[0023]
The pixel deformation optical system 14 includes a plurality of cylindrical lens arrays 30, a cylindrical lens 31, and a cylindrical lens array 32 in order from the two-dimensional spatial light modulator 13 side. The cylindrical lens arrays 30 and 32 are arranged in the horizontal direction by the same number of cylindrical lenses as shown in FIG. 2 having the refractive power only in the plane shown in FIG. The image 12a of each pixel is reduced and formed in a state where a gap is generated between them. On the other hand, the cylindrical lens 31 has refractive power only in the plane shown in FIG. 3, and reduces the image 12a of pixels arranged adjacent to each other in the vertical direction of the two-dimensional spatial light modulator 13. Here, the pixel reduction rate by the cylindrical lens 31 and the pixel reduction rate by the cylindrical lens arrays 30 and 32 are set to be equal to each other.
[0024]
In addition, instead of the cylindrical lens 31 used in the pixel deformation optical system 14, another anamorphic optical system may be used to refract light only within the plane shown in FIG.
[0025]
FIG. 4 shows the above in an easy-to-understand manner. FIG. 2A shows a state in which pixels are juxtaposed in the two-dimensional spatial light modulator 13, FIG. 2B shows a pixel deformation image by a cylindrical lens 31, and FIG. 3C shows a cylindrical lens array 30 and 32. Each pixel deformation image is shown.
[0026]
The image of the pixel 12 formed as described above is imaged and projected onto the photosensitive recording medium 17 by the imaging lens 15 as shown in FIGS. FIG. 5 shows a pixel row image 12b projected on the photosensitive recording medium 17. As shown in FIG. As shown in the figure, the long photosensitive recording medium 17 is disposed at an angle θ with respect to the pixel array image 12b, and is sent in the length direction thereof. This photosensitive recording medium feed direction (arrow y direction) is referred to as the sub-scanning direction, and the direction perpendicular to it (arrow x direction) is referred to as the main scanning direction. The main scanning direction x and the sub-scanning direction y may be set slightly deviated from directions that are completely orthogonal to each other.
[0027]
Here, the angle θ is an angle that substantially satisfies the relationship L · tan θ = p, where the length and interval of the pixel array image 12b are L and p, respectively. As a result, even if there are gaps between the pixel array images 12b, when the photosensitive recording medium 17 is moved in the sub-scanning direction, the photosensitive recording medium 17 is either one over the entire effective main scanning width. With this pixel image, writing is performed without a gap.
[0028]
Next, driving of the two-dimensional spatial light modulator 13 will be described with reference to FIGS. In FIG. 6, each of the squares forming the diagonal row is not a pixel 12 itself of the two-dimensional spatial light modulator 13 but a pixel image, but for the sake of simplification of explanation, Is described as “pixel”.
[0029]
In this example, it is assumed that one pixel column of the two-dimensional spatial light modulator 13 is composed of 20 pixels 12. Of these 20 pixels 12, one pixel is recorded by a pixel group composed of j = 5 pixels adjacent to each other, and therefore k = 4 pixels per pixel column in the main scanning direction. Is to be recorded.
[0030]
That is, as shown in FIG. 6, the first recording pixel m11 arranged in the main scanning direction is recorded by the five pixels R111, R112, R113, R114, R115 of the first pixel column, and the next five pixels are recorded. The second recording pixel m12 arranged in the main scanning direction is recorded by R121, R122, R123, R124, and R125, and the third recording arranged in the main scanning direction by the next five pixels R131, R132, R133, R134, and R135. The pixel m13 is recorded, and the fourth recording pixel m14 arranged in the main scanning direction is recorded by the next five pixels R141, R142, R143, R144, and R145. Then, the fifth recording pixel m21 arranged in the main scanning direction is recorded by the five pixels R211, R212, R213, R214, and R215 of the second pixel column, and thereafter, similarly, the total number of pixel columns is 4 Double the number of recording pixels arranged in one direction and recorded, and one main scanning line is recorded.
[0031]
FIG. 7 shows the drive timing of each pixel 12 of the two-dimensional spatial light modulator 13 controlled by the spatial light modulator control unit 21 to perform the above-described recording. As shown in FIG. 1, the spatial light modulator control unit 21 determines the opening / closing timing and the opening (transmittance) of each pixel 12 based on an image signal S carrying a two-dimensional gradation image input thereto. Control. The pulse waveform for each pixel in FIG. 7 indicates the opening / closing timing and the exposure amount corresponding to the opening (this is represented by the height of the pulse waveform). For example, the total exposure amount for the recording pixel m11 is the sum of the exposure amounts by the pixels R111, R112, R113, R114, and R115 within the time T11 in the figure. The same applies to the total exposure amount for other recording pixels.
[0032]
As described above, in order to change the opening degree of each pixel 12, it may be changed continuously by controlling the voltage applied thereto, or it may be kept open within a certain open period. The time to be kept may be controlled, and further, the number of times of opening in the form of a pulse in a predetermined cycle within a certain open period may be controlled.
[0033]
Note that if the delay time indicated by Td in FIG. 7 is set between the start of driving adjacent pixel columns, the positional deviation in the sub-scanning direction due to the inclination of the pixel columns is compensated, and A plurality of recording pixels forming one main scanning line can be recorded at the same position in the sub-scanning direction.
[0034]
Next, another embodiment of the present invention will be described with reference to FIG. In FIG. 8, elements that are the same as those already described are given the same reference numerals, and redundant descriptions thereof are omitted (the same applies hereinafter).
[0035]
In the above-described embodiment, the transmission type two-dimensional spatial light modulation element 13 is used. However, as shown in FIG. 8, the reflection type two-dimensional spatial light modulation element 40 is used in this embodiment. Yes. As such a reflective two-dimensional spatial light modulator 40, for example, a reflective liquid crystal panel, a DMD (digital micromirror device), or the like can be applied.
[0036]
The recording light 10 that is reflected by the two-dimensional spatial light modulation element 40 and carries an image by each pixel 41 is guided to a cylindrical lens array 30 similar to that shown in FIG. Subsequent deformation, reduction, and projection of the pixel image are performed in the same manner as in the previous embodiment.
[0037]
In the present invention, since the pixel array image of the two-dimensional spatial light modulator is tilted with respect to the sub-scanning direction on the photosensitive recording medium, the recording position of each pixel is the main scanning in the multiple recording of one pixel by j pixels. There is a possibility that the recording pixel width increases and interference occurs between the recording pixels. In order to prevent this, as shown in FIG. 9 (1), some of the pixels forming one pixel column of the two-dimensional spatial light modulator are not used (hatched in the figure). It may be as well.
[0038]
The recording pixel width in such a case is the width indicated by d1 in FIG. On the other hand, the recording pixel width when using all the pixels of the two-dimensional spatial light modulator (in this example, seven per recording pixel) is large as indicated by d2 in FIG.
[0039]
Further, there is no problem in controlling j pixels (j ≧ 2) adjacent to each other for recording one recording pixel so that the opening degree is always equal to each other. When control is performed so that different pixels are mixed, the pixel recording position may move in the main scanning direction in accordance with the exposure amount (that is, recording density). FIG. 10 illustrates this.
[0040]
For example, here, it is assumed that one recording pixel is recorded with j = 9 pixels adjacent to each other, and the lower pixel is opened sequentially from the upper pixel in FIG. 10 as the exposure amount increases. . In this case, when the exposure amount is relatively small, for example, as shown in FIG. 1A, only the uppermost one pixel is opened, and a relatively low density recording pixel is relatively illustrated in the sub-scanning direction. It is recorded so that the center is located on the middle left side. On the other hand, when the exposure amount is relatively large, all the pixels are opened, for example, as shown in FIG. 2B, and the center of the relatively high density recording pixel is located on the right side of the drawing as compared with the above case. Will be recorded as follows.
[0041]
In order to prevent this problem, when the exposure amount is minimum, the center pixel is opened among j = 9 pixels, and the pixels on the edge side are sequentially opened from there as the exposure amount increases. Thus, the driving of the two-dimensional spatial light modulator may be controlled.
[0042]
Although the embodiment for recording a monochrome gradation image has been described above, the image recording apparatus of the present invention can be configured to record a color gradation image. Hereinafter, an embodiment configured as described above will be described with reference to FIG. 11 and FIG. 12.
[0043]
FIG. 11 shows a two-dimensional spatial light modulator 50 formed for recording a color gradation image. The two-dimensional spatial light modulator 50 has a plurality of pixels 51 arranged two-dimensionally, and has a red filter 52R, a green filter 52G, and a blue filter in three regions divided in the vertical direction in the figure. 52B is attached.
[0044]
By combining the two-dimensional spatial light modulator 50 with the optical system 16 shown in FIGS. 2 and 3, for example, an image of the pixel array of the light modulator 50 is obtained as a color photosensitive recording medium 53 as shown in FIG. Can be imaged and projected onto. In the figure, 54R is a red pixel row image, 54G is a green pixel row image, and 54B blue pixel row image. Then, by moving the color photosensitive recording medium 53 in the sub-scanning direction, the same portion of the color photosensitive recording medium 53 can be sequentially exposed with red light, green light, and blue light, and a color image can be recorded on the recording medium 53. .
[0045]
In order to record a color image, in addition to using the color filter as described above, a three-color light source is used, and they are driven in a time-sharing manner in synchronization with the sub-scan feed of the color photosensitive recording medium. Exposure may be performed.
[Brief description of the drawings]
FIG. 1 is a schematic perspective view showing an image recording apparatus according to an embodiment of the present invention. FIG. 2 is a plan view showing a part of the image recording apparatus. FIG. 3 is a side view showing a part of the image recording apparatus. FIG. 4 is a diagram for explaining the operation of a pixel deformation optical system of the image recording apparatus. FIG. 5 is a diagram showing a relationship between a pixel image and a photosensitive recording medium in the image recording apparatus. FIG. 7 is a diagram illustrating a method for driving a spatial light modulation element. FIG. 7 is a diagram illustrating a method for driving a two-dimensional spatial light modulation element in the image recording apparatus. FIG. 8 is an optical system used in another embodiment of the present invention. FIG. 9 is a diagram for explaining another method for driving a two-dimensional spatial light modulator according to the present invention. FIG. 10 is a diagram for explaining another method for driving a two-dimensional spatial light modulator according to the present invention. A two-dimensional sky used in another embodiment of the present invention Front view of the optical modulator 12] [Description of symbols is a graph showing a relation between a pixel image and the photosensitive recording medium by the two-dimensional spatial light modulator of FIG. 11
10 Recording light
11 Light source
12 Pixels of 2D spatial light modulator
12a pixel image
12b Pixel array image
13 Two-dimensional spatial light modulator
14 pixel deformation optics
15 Imaging lens
16 optics
17 Photosensitive recording media
18 Sub-scanning means
20 Light source controller
21 Spatial light modulator control unit
22 Sub-scan feed controller
23 Overall control unit
30, 32 Cylindrical lens array
31 Cylindrical lens
40, 50 Two-dimensional spatial light modulator
51 Pixels of two-dimensional spatial light modulator
52R Red filter
52G Green filter
52B Blue filter
53 Color photosensitive recording media
54R Red pixel array image
54G Green pixel array image
54B Blue pixel array image

Claims (8)

A light source that emits recording light;
A two-dimensional spatial light modulation element that has a plurality of pixels arranged two-dimensionally in a state of being adjacent to each other in one direction and another direction orthogonal thereto, and modulates the recording light;
Each pixel of the two-dimensional spatial light modulator is placed in a state in which pixels are adjacent to each other without any gap in one pixel arrangement direction to form a pixel row, and between the pixels in another pixel arrangement direction. An optical system that forms an image in a state where a void is generated;
A sub-scanning unit that disposes a photosensitive recording medium at an image forming position of the optical system, and that sub-scans the photosensitive recording medium in a direction that is inclined with respect to the pixel row and crosses the other pixel arrangement direction;
The two-dimensional spatial light modulation element is composed of k pixel groups (k ≧ 2) each composed of j pixels (j ≧ 2) adjacent to each other in one of the pixel columns, and the sub-scanning movement is performed. An image recording apparatus comprising control means for driving so as to record k pixels arranged in the main scanning direction substantially orthogonal to the direction. The optical system has an refracting power only in the one pixel arrangement direction and anamorphic optical system for overall reduction of the pixel row;
The image recording apparatus according to claim 1, further comprising a cylindrical lens array optical system that has a refractive power only in the other pixel arrangement direction and individually reduces the plurality of pixels.   The pixel rows of the two-dimensional spatial light modulation element are compensated for so as to compensate for the recording time shift between the pixel rows due to the tilt of the image of the pixel row of the two-dimensional spatial light modulation element on the photosensitive recording medium. The image recording apparatus according to claim 1, wherein a delay is set in the driving time.   Color filters of different colors are attached to the plurality of divided regions of the two-dimensional spatial light modulation element, and the same portion of the color photosensitive recording medium is irradiated with the recording light that has passed through each color filter, and the photosensitive recording medium is colored. 4. The image recording apparatus according to claim 1, wherein an image can be recorded.   A plurality of light sources that emit light of different wavelengths are used as the light source, and the plurality of light sources are driven in a time-sharing manner in synchronization with the sub-scan feed of the color photosensitive recording medium to record a color image on the photosensitive recording medium. The image recording apparatus according to claim 1, wherein the image recording apparatus is an image recording apparatus.   The image recording apparatus according to claim 1, wherein a pixel that is not used for image recording exists between the pixel group.   When a plurality of pixels in the pixel group has a minimum required exposure amount, one pixel at the center of the pixel group is in a light-passing state, and as the required exposure amount increases, the pixels on the pixel group end side gradually increase. The image recording apparatus according to claim 1, wherein the image recording apparatus is driven so as to be in a light passing state. Recording light is modulated by a two-dimensional spatial light modulation element having a plurality of pixels arranged two-dimensionally in one direction and in a direction perpendicular to each other and recorded on a photosensitive recording medium. In the next step a), each pixel of the two-dimensional spatial light modulator is placed in a state in which pixels are adjacent to each other in the pixel arrangement direction without forming a gap, thereby forming a pixel row. An image of the two-dimensional spatial light modulator is formed on the photosensitive recording medium in such a state that a gap is generated between the pixels in the pixel arrangement direction.
b) k pixels arranged in one direction of the photosensitive recording medium by k pixel groups (k ≧ 2) each composed of j pixels (j ≧ 2) adjacent to each other in one of the pixel columns. Record,
c) The photosensitive recording medium is recorded by sub-scanning movement in a direction inclined with respect to the pixel row.
An image recording method comprising:

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