JPH117084A - Image exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To use a spatial optical modulation element having general picture element structure as it is in an image exposure device where a picture element is shifted. SOLUTION: In this image exposure device where recording light L emitted from a light source 11 is modulated by the spatial optical modulation element 15 having plural picture elements arranged in a two-dimensional array state so as to irradiate photosensitive material 10; a light shielding mask 17 having plural apertures which are two-dimensionally juxtaposed at a pitch in similar relation to the two-dimensional disposing pitch of the picture element and whose numerical aperture in each arranging direction is <=50% is arranged between the light source 11 and the element 15. The image of the mask 17 is formed on the element 15 by an image-formation lens 14 so that each aperture part is positioned on one picture element. The mask 17 is moved by a driving means 18 so that the position of the aperture part on the picture element of the element 15 may be successively changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for exposing an image to a photosensitive material using a spatial light modulator such as a liquid crystal panel or a mirror array device, and more particularly, to a method for performing high-definition images by performing pixel shift. The present invention relates to an image exposure apparatus capable of performing exposure.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal panel has been known as a typical spatial light modulator. As a spatial light modulator, as shown in, for example, Japanese Patent Application Laid-Open No. 5-150173, a plurality of micromirrors arranged in a two-dimensional array and a drive for independently changing the direction of each of these micromirrors. And a mirror array device that selectively reflects incident light in one of two directions for each micromirror.

When such a mirror array device is used, by controlling the operation of the driving section according to an image signal, light incident on a predetermined projection surface via a minute mirror, each of which constitutes one pixel, is minutely reflected. An image can be projected on the projection surface by modulating each mirror. If a photosensitive material is arranged on the projection surface, an image can be exposed on the photosensitive material. In such a case, the on-time of each micromirror (the time during which light is incident on the photosensitive material) within the frame time is pulse-width-modulated, for example, so that each micromirror is incident on the photosensitive material. It is also possible to control the amount of light to expose a gradation image.

In the case where other spatial light modulators such as the liquid crystal panel described above are used, an image can be exposed on the photosensitive material by projecting similarly modulated recording light onto the photosensitive material.

By the way, when an image is exposed on a photosensitive material using the spatial modulation element as described above, it has been proposed to increase the pixel density of an exposed image to achieve higher definition by a technique called "pixel shift". I have. As shown in, for example, Japanese Patent Application Laid-Open No. 8-227108, this pixel shift is performed between the exposure dots on the photosensitive material formed by the light passing through the pixels of the spatial modulation element, and further between the exposure dots. In this method, the optical relationship between the spatial modulation element and the photosensitive material is changed so as to form an exposure dot by passing light, and image exposure is performed each time the optical relationship is changed.

Although the above-mentioned exposure dots are "pixels" with respect to the exposed image, in this specification, in order to avoid confusion with the pixel of the spatial modulation element, the exposed image is basically defined in this way. The term "exposure dot" is used.

Specifically, i spatial modulation elements are provided in the X direction,
In a case where j pixels are arranged in an array in the Y direction, if pixel shifting is performed once each in the X and Y directions, 2i pixels in the X and Y directions on the photosensitive material can be obtained.
2j exposure dots are recorded in the Y direction. That is, in this case, the same number of exposure dots can be recorded as in the case where exposure is performed once using 4 (i × j) spatial modulation elements, and high definition of an image is achieved.

In order to change the optical relationship between the spatial modulation element and the photosensitive material as described above, the spatial modulation element is moved, the photosensitive material is moved, or an optical member interposed between the two. Can be used.

In general, it is difficult to integrate a large number of pixels at a high density in a spatial modulation element such as a liquid crystal panel. However, if the above-described pixel shift is applied, the number of pixels is relatively small and the number of pixels is low. Even when using spatial modulation elements arranged in density,
High-density images can be exposed.

[0010]

However, conventionally, in order to perform the pixel shift, it is necessary to newly create a spatial light modulator having a special pixel structure.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an image exposure apparatus which can perform pixel shift using a spatial light modulator having a general pixel structure as it is. Things.

[0012]

SUMMARY OF THE INVENTION An image exposure apparatus according to the present invention uses a light-shielding mask having a plurality of openings through which recording light passes so as to make pixels of a spatial light modulation element seemingly finer. The pixel shift can be performed by using a spatial light modulation element having a simple pixel structure as it is. Specifically, a light source that emits recording light for exposing a photosensitive material and a plurality of light sources arranged in a two-dimensional array are provided. A spatial light modulation element disposed at a position for receiving the recording light, a projection optical system for projecting the recording light having passed through the spatial light modulation element onto a photosensitive material, and a two-dimensional A plurality of openings arranged two-dimensionally at a pitch similar to the arrangement pitch and having an aperture ratio of 50% or less in each arrangement direction, between the light source and the spatial light modulator; Disposed in an optical path of the recording light. A light-shielding mask, a mask image-forming optical system that forms an image of the light-shielding mask on the spatial light modulator so that each of the openings is positioned on one pixel, and Pixel shift means for changing the relative position between the image of the light-shielding mask and the spatial light modulator so that the position on the pixel sequentially changes, and each time the relative position changes by the pixel shift means, each pixel And a modulation circuit for controlling the spatial light modulation element so as to modulate the recording light.

[0013]

The relative position between the image of the light-shielding mask and the spatial light modulator is changed to change the position of each opening of the light-shielding mask image on the pixel of the spatial light modulator. Each time the position changes, the position of the pixel except the opening of the light-shielding mask image changes. That is, apparently, pixels smaller than the actual pixels of the spatial light modulator are in the same state as sequentially changing positions. Therefore, every time the position of the pixel apparently changes in this way, if the recording light is spatially modulated by the spatial light modulator to perform image exposure,
High-definition images can be exposed in the same manner as when performing normal pixel shift.

In this apparatus, since the pixels of the spatial light modulator are made apparently finer by using the above-described light-shielding mask, a spatial light modulator having a general pixel structure can be used as it is. In addition, the apparatus cost can be kept low.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows an image exposure apparatus according to one embodiment of the present invention.

As shown in the figure, the image exposure apparatus includes a light source 11 such as a halogen lamp that emits a non-polarized recording light L for exposing a photosensitive material 10 and a light source 11 disposed near a focal position. A condenser lens 12 for collimating the recording light L emitted from the light source 11, and a collimating recording light L
A polarizing beam splitter 13 disposed at a position where
An imaging lens 14 arranged at a position where the s-wave component of the recording light L reflected by the film surface 13a of the polarization beam splitter 13 is incident.
A reflection type liquid crystal panel 15 disposed at a position where the s-wave recording light L passing through the imaging lens 14 is incident; and a projection lens 16 disposed between the polarization beam splitter 13 and the photosensitive material 10. And

Also, the condenser lens 12 and the polarization beam splitter
A light-shielding mask 17 having a large number of minute openings arranged two-dimensionally is arranged in the optical path of the recording light L between the light-shielding mask 13 and the recording light L.
The light-shielding mask 17 is made movable in two juxtaposed directions of the openings by a pixel shift driving means 18 composed of, for example, two piezoelectric elements. The operation of the driving means 18 is controlled by a pixel shift control circuit 19.

On the other hand, the above-mentioned liquid crystal panel 15 includes a transparent whole-surface common electrode and a two-dimensional matrix pixel electrode arranged so as to sandwich a liquid crystal layer, and a switch matrix for controlling an applied voltage between each pixel electrode and the common electrode. Have
The operation of the liquid crystal panel 15 is based on an image signal S indicating a gradation image.
Is controlled by the modulation control circuit 20 to which is input. The modulation control circuit 20 and the pixel shift control circuit 19 are controlled by an overall control device 21.

Next, the operation of the image exposure apparatus will be described. At the time of image exposure, the light source 11 is turned on, and the unpolarized recording light L emitted from the light source 11 enters the polarization beam splitter 13. Of the recording light L, a polarization beam splitter
The component incident as a p-wave on the film surface 13a of the
Is transmitted, and the component incident as an s-wave is reflected by the film surface 13a and enters the imaging lens 14. The recording light L condensed by the imaging lens 14 is reflected by the liquid crystal panel 15 and is spatially modulated by the liquid crystal panel 15 at that time.

That is, the modulation control circuit 20 controls the voltage applied to each pixel (the portion between the common electrode and one pixel electrode) of the liquid crystal panel 15 based on the input image signal S, Controls the tilt of the liquid crystal molecules for each pixel. Therefore, the recording light L incident on the liquid crystal panel 15 is modulated into a polarization form according to the inclination of the liquid crystal molecules, and is converted into elliptically polarized light or circularly polarized light.

The modulated recording light L is applied to an imaging lens
After passing through 14, the light re-enters the film surface 13a of the polarizing beam splitter 13. At this time, the recording light L is s for each pixel of the liquid crystal panel 15.
A state between a wave state (in the case of no modulation) and a p-wave state (in the case of maximum modulation) is taken. The s-wave component of the recording light L is reflected by the film surface 13a, while the p-wave component is transmitted through the film surface 13a and enters the projection lens 16, where the s-wave component is projected onto the photosensitive material 10.

As described above, the recording light L whose intensity has been modulated based on the image signal S for each pixel of the liquid crystal panel 15 is projected on the photosensitive material 10 and the floor indicated by the image signal S is projected on the photosensitive material 10. The toned image is exposed.

In this embodiment, a monochrome image is exposed, but an R (red) filter and a G (green) filter are used.
By sequentially inserting each color filter of the filter and the B (blue) filter into the optical path of the recording light L, and driving the liquid crystal panel 15 based on each color image signal corresponding to the color while each color filter is inserted, It is also possible to expose a color image to a color photosensitive material.

Next, the pixel shift will be described. During the period of exposing one image, the position of the light-shielding mask 17 is changed in four ways by the driving means 18, and each time the image is exposed based on the image signal S.

That is, the liquid crystal panel 15 is driven in a state where the light shielding mask 17 is arranged at the first position. At this time, due to the action of the imaging lens 14, the light shielding mask is placed on the liquid crystal panel 15.
17 images are formed in the state shown in FIG. That is, as shown in the figure, the light-shielding masks 17 are formed in two-dimensionally arranged at pitches similar to the two-dimensionally arranged pitches of the pixels 15a of the liquid crystal panel 15, and are arranged in the respective openings in the respective arrangement directions. It has a plurality of openings 17a whose ratio is slightly lower than 50%, and the light-shielding mask is placed in such a state that these openings 17a are located on a region A of about 1/4 of each pixel 15a of the liquid crystal panel 15. 17 images are formed.

At this time, the liquid crystal panel 15 is driven based on an image signal S relating to pixels in odd rows and odd columns of an image to be exposed. As a result, the photosensitive material 10
Exposure dots D are recorded as indicated by "1" in (1) of FIG. In FIG. 3, the shape of the exposure dot D is schematically shown as a circle.

Next, the light-shielding mask 17 is moved by a predetermined amount in the direction perpendicular to the plane of FIG. 1 by the driving means 18 and arranged at the second position, and the liquid crystal panel 15 is driven in this state. At this time, an image of the light-shielding mask 17 is formed in a state where the opening 17a of the light-shielding mask 17 is located on a region B (see FIG. 2) of about 1/4 of each pixel 15a of the liquid crystal panel 15. .

At this time, the liquid crystal panel 15 is driven based on an image signal S relating to pixels in odd rows and even columns of an image to be exposed. As a result, the photosensitive material 10 has an exposure dot D as shown in FIG.
Is recorded.

Next, the light-shielding mask 17 is moved by a predetermined amount in a direction parallel to the plane of FIG. 1 by the driving means 18 and arranged at the third position, and the liquid crystal panel 15 is driven in this state. At this time, the image of the light-shielding mask 17 is formed in a state where the opening 17a of the light-shielding mask 17 is located on a region C (see FIG. 2) of about 1/4 of each pixel 15a of the liquid crystal panel 15. .

At this time, the liquid crystal panel 15 is driven based on an image signal S relating to pixels in even rows and even columns of an image to be exposed. As a result, the photosensitive material 10 has an exposure dot D as shown by adding “3” in FIG.
Is recorded.

Next, the light-shielding mask 17 is moved by a predetermined amount in the direction perpendicular to the plane of FIG. 1 by the driving means 18 and is arranged at the fourth position, and the liquid crystal panel 15 is driven in this state. At this time, the image of the light-shielding mask 17 is formed in a state where the portion of the opening 17a of the light-shielding mask 17 is located on a region D (see FIG. 2) of about 1/4 of each pixel 15a of the liquid crystal panel 15. .

At this time, the liquid crystal panel 15 is driven based on an image signal S relating to pixels in even rows and odd columns of an image to be exposed. As a result, the photosensitive material 10 has an exposure dot D as shown by adding "4" in FIG.
Is recorded.

As described above, the pixel 15 of the liquid crystal panel 15
Since the pixel shift is performed once in each of the arrangement directions X and Y, the exposure dots D in each of these directions X and Y are twice as many as the number of pixels 15a arranged in parallel.
Is recorded, and a high-definition image is exposed.

Thereafter, the photosensitive material 10 undergoes a normal developing process, whereby the exposed image is visualized.

In the above example, the pixel 15 of the liquid crystal panel 15
The pixel shift is performed once in each of the arrangement directions X and Y of a, but the number of pixel shifts is not limited to this. For example, if the pixel shift is performed twice in each of the arrangement directions X and Y of the pixels 15a, the exposure dots D that are three times the number of the pixels 15a arranged in each of these directions X and Y are recorded. In this case, the light-shielding mask 17 may have an aperture ratio of about 33% in each direction in which the openings 17a are arranged.

In the present invention, not only the liquid crystal panel but also other reflective or transmissive spatial light modulators such as the above-mentioned mirror array device can of course be used. Furthermore, even when a liquid crystal panel is used, the liquid crystal panel is not limited to the electric address type described in the above embodiment.
An optical address type liquid crystal panel is also applicable.

[Brief description of the drawings]

FIG. 1 is a plan view of an image exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing a positional relationship between a pixel of a liquid crystal panel and a light shielding mask image in the image exposure apparatus.

FIG. 3 is a schematic diagram illustrating a recording state of exposure dots by the image exposure apparatus.

[Explanation of symbols]

 10 Photosensitive material 11 Light source 12 Condensing lens 13 Polarizing beam splitter 14 Imaging lens 15 Liquid crystal panel 15a Liquid crystal panel pixel 16 Projection lens 17 Light shielding mask 17a Light shielding mask opening 18 Pixel shift driving means 19 Pixel shift control circuit 20 Modulation control Circuit 21 Overall control device L Recording light

Claims (1)

[Claims] 1. A light source for emitting recording light for exposing a photosensitive material, a spatial light modulator having a plurality of pixels arranged in a two-dimensional array, and arranged at a position for receiving the recording light; A projection optical system for projecting the recording light having passed through the spatial light modulation element onto a photosensitive material, and each arrangement direction two-dimensionally arranged at a pitch similar to the two-dimensional arrangement pitch of the pixels. A plurality of apertures each having an aperture ratio of 50% or less, and a light-shielding mask disposed in the optical path of the recording light between the light source and the spatial light modulator; A mask image forming optical system for forming an image so that each of the openings is positioned on one pixel, and the light-shielding mask so that the position of the opening on the pixel is sequentially changed. The relative position between the image of the A pixel shifting unit that, each time the relative position is changed by the pixel shifting means, the image exposure device including a modulation circuit for controlling said spatial light modulator to modulate the recording light by each pixel.