JPH1052942A - Color exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a multichannel color exposure device, with which color images can be recorded at a high speed and which has a highly productive and simple structure, by a method wherein a color photosensitive material is scanned planarly with a plurality of modulated light beams imaged by means of a reduction optical system. SOLUTION: A color photosensitive material is scanned planarly with a plurality of modulated light beams imaged by means of a reduction optical system. An exposure device 10 consists of a light source part 12, a shaping optical system 14, a light modulator 16, an imagery optical system 18 and the like. An exposure device 10 executes an image exposure by planarly scanning a color photosensitive material A with recording light beams through a main scanning performed by applying the recording light beams modulated with the light modulator 16 to the rotating color photosensitive material A while an exposure drum 22, onto the outer peripheral surface of which the color photosensitive material A is closely contactingly held, is rotated to the direction indicated with the arrow (a) and through a sub-scanning performed by moving an optical unit 20 to the direction, which is normal to the rotational direction of the exposure drum 22 or indicated with the arrow (b) or parallel to the rotary shaft of the exposure drum 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color exposure apparatus for recording an image by scanning and exposing a color photosensitive material with a plurality of light beams, and more particularly, to a color exposure apparatus for emitting at least three kinds of light beams having different wavelengths. The present invention relates to a multi-channel color exposure apparatus capable of recording a color image on a color photosensitive material at high speed and with high image quality using a light source and the same number of temperature-controlled spatial modulation elements as those light sources.

[0002]

2. Description of the Related Art Exposure devices for scanning and exposing a photosensitive material such as a silver halide photographic material or an electrophotographic photosensitive member with a light beam modulated according to an image to be recorded are used in various printers and copying machines. At present, as such an exposure apparatus, there are an exposure apparatus of a plane scanning type and an exposure apparatus of a drum scanning type. The planar scanning type light beam scanning exposure apparatus deflects a light beam modulated according to a recorded image in the main scanning direction using an optical deflector such as a polygon mirror or a resonant scanner, and simultaneously deflects a photosensitive material into a light beam. The photosensitive material is two-dimensionally scanned and exposed by a modulated light beam by relatively moving in a sub-scanning direction substantially orthogonal to the main scanning direction, thereby recording an image (latent image or visible image). .

On the other hand, a drum-scanning light beam scanning exposure apparatus (drum scanner) irradiates a photosensitive material on a rotating drum with a light beam modulated in accordance with a recorded image to perform main scanning and performs drum scanning. The light beam is moved in the direction of the central axis to perform sub-scanning, whereby the photosensitive material is two-dimensionally scanned and exposed by the modulated light beam to record an image (latent image or visible image).

[0004]

However, when exposing an image to a large-sized photosensitive material such as A1 size (660 mm × 1010 mm) with one light beam, it is necessary to increase productivity. Since high-speed main scanning and sub-scanning are required, it is necessary to make the device configuration robust so that exposure unevenness due to scanning deviation does not occur. For example, in the flat-scanning method, a transfer table for fixing the photosensitive material for high-speed sub-scanning conveyance of the photosensitive material with respect to high-speed main scanning by a high-speed rotating optical deflector, and conveyance for holding or placing and conveying the photosensitive material It is necessary to make not only the structure of the roller pair and the transport belt and the like, but also the structure of the base, the platen and the housing that support them. In the drum scanning method,
It is necessary to rotate the drum at a high speed, and it is necessary to make a structure such as a housing for supporting the drum solid. Furthermore, a housing having a solid structure particularly requires measures against vibration. For this reason, the conventional scanning method has a problem that the exposure apparatus becomes more expensive. Further, in the case of the plane scanning method, there is a problem in that the beam diameter and scanning length of the light beam are limited, the main scanning angle is determined, and the size of the photosensitive material that can be exposed is limited. For this reason, there is also a problem in that, when the optical path length is increased to support a large-sized photosensitive material, the resolution is limited and the image quality is reduced.

[0005] In addition, in a conventional exposure apparatus,
In order to record three colors on a large-size color photosensitive material, it is necessary to combine three light beams for producing each color in order to form one light beam. A high-performance optical system is required.
If the recording is to be performed with the light beam of a book, the arrangement of the optical system becomes complicated, and there is also a problem that it is necessary to increase the positional accuracy of each element. For this reason, it is easiest to record a color image with one light beam for each color in RGB or CMY plane-sequentially with an optical system configuration. However, when plane-sequential recording is performed, a photosensitive material or a light beam (light source) is used. There is also a problem that productivity does not increase due to the necessity of reciprocating.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art, and to provide a high productivity, inexpensive, and simple multi-channel color printer capable of recording a color image on a large-sized color photosensitive material at high speed. An exposure apparatus is provided.

[0007]

In order to achieve the above object, the present invention provides a plurality of light sources for emitting light beams having different narrowband wavelengths, and a light source for shaping the light beams emitted from these light sources. A beam shaping optical system, and a plurality of spatial modulation elements provided corresponding to each of the plurality of light sources, each of which modulates each light beam shaped by the light beam shaping optical system according to an image signal to be recorded. A reduction optical system for reducing the modulated light beam modulated by these spatial modulation elements on a color photosensitive material to form an image, and a plurality of modulated light beams formed by the reduced optical system to form the color photosensitive material. A color exposure apparatus having a scanning unit for performing two-dimensional scanning.

Here, it is preferable that the spatial modulation element is a multi-channel spatial modulation element having a plurality of modulation windows that are independently modulated. Further, it is preferable that the spatial modulation element has a temperature control unit. In addition, it is preferable that at least two of the light sources emit light beams that emit the same light.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color exposure apparatus according to the present invention will be described in detail below based on a preferred embodiment shown in the accompanying drawings. FIG. 1 is a schematic perspective view conceptually showing one embodiment of the color exposure apparatus of the present invention. FIG. 2A is an explanatory view schematically showing a cross section of the configuration of the color exposure apparatus shown in FIG. 1, and FIG. 2B is a conceptual view showing another embodiment of the color exposure apparatus of the present invention. FIG.

As shown in FIGS. 1 and 2 (a), a color exposure apparatus (hereinafter simply referred to as an exposure apparatus) 10 of the present invention.
Basically, a light source unit 12, a shaping optical system 14, an optical modulator 16, an imaging optical system 18, and the like include a housing (not shown).
And an optical unit 20 housed in a unit, and a cylindrical exposure drum 22. Exposure apparatus 1 in illustrated example
0 denotes the light modulator 16 while rotating the exposure drum 22 having the color photosensitive material A in close contact with the outer peripheral surface in the direction of arrow a in the figure.
The recording light beam L (L _M , L _C , L _Y ) modulated by the above is irradiated on the rotating color photosensitive material A to perform main scanning, and the optical unit 20 is moved in the direction of the arrow b perpendicular to the rotation direction of the exposure drum 22. that is, by parallel moving the rotational axis of the exposure drum 22 to the sub-scanning, the recording light beam L a color light-sensitive material _{a (L M, L C,} L Y) and two-dimensional scanning to image exposure by Is what you do. The present invention is not limited to moving the optical unit 20 for sub-scanning, but may be configured to rotate the exposure drum 22 in the direction of arrow a and simultaneously move in the direction of arrow b for sub-scanning. .

The light source unit 12 converts a color image into a color photosensitive material.
Three recording light beams L for recording on material A_M, L_C,
L_Y(Hereinafter collectively referred to as L)
And three light sources 12M, 12C, and 12Y. Illustrated example
Then, these three light sources 12M, 12C, and 12Y
Color light-sensitive material (hereinafter simply referred to as light-sensitive material) A spectrum
Recording light beams with different narrowband wavelengths according to sensitivity characteristics
L_M, L_C, L _Y) For each laser beam
Iodine (LD). Here, for example, as shown in FIG.
The maximum sensitivity in the infrared region for two of the three primary colors.
False-color photothermographic material with spectral sensitivity characteristics
(Pictrographic photosensitive material (Fuji Photo Film Co., Ltd.
), The light source 12M has a wavelength of 680 nm.
Magenta (M) coloring laser beam L_ML to inject
D, and the light source 12C is cyan (C) having a wavelength of 750 nm.
Laser beam L for coloring_CAnd a light source 12
Y is a laser beam for yellow (Y) coloring at a wavelength of 810 nm.
Room L_YCan be obtained. Of the present invention
In the exposure device 10, recording is performed by the optical modulator 16.
The light beam L is modulated according to a color recording image.
Therefore, the light sources 12M, 12C, 12Y
During image recording, the light beam L is continuously emitted.

The light source used in the present invention is not limited to these LDs, but is a narrow light source capable of emitting the colors of a color photosensitive material, for example, three primary colors (M, C, Y or R, G, B). Any light source may be used as long as it can emit the recording light beam L of the band wavelength, and for example, a semiconductor laser, an LED, a gas laser, a wavelength conversion laser using an SHG element, or the like can be used. On the other hand, as the color photosensitive material A used in the present invention, a material capable of emitting three primary colors by a light source that emits at least three recording light beams having different wavelengths and a narrow band wavelength is used.
There is no particular limitation, and examples thereof include photothermographic materials such as the false-color photothermographic material shown in FIG. 7, ordinary silver halide photographic materials, and pressure-sensitive photographic materials.
Therefore, in the present invention, a light source that emits a recording light beam having an appropriate narrow-band wavelength may be selected according to the spectral sensitivity characteristics of the color photosensitive material, or a light source that emits a narrow-band wavelength according to the narrow-band wavelength of the light beam emitted by the light source may be selected. In this case, an appropriate color light-sensitive material may be selected, or a material in which the combination of both is appropriate may be selected.

The shaping optical system 14 includes light sources 12M, 12C,
The light beams L _M , L _C , and L _Y emitted from the light source 12Y are horizontally elongated (long in the direction of arrow b) substantially parallel light beams, and the parallel light beams L _M , L _C , and L _Y are converted into an optical modulator 16 described later. (The corresponding spatial modulation elements 24M, 24C, 24Y)
Are formed so as to be able to irradiate the entire surface of the entire modulation window with a sufficient, preferably uniform light amount without excess and deficiency, and are provided corresponding to the light sources 12M, 12C, and 12Y, respectively.
Each light beam L _M, L _C, acting respectively on L _Y, vertical direction (direction of arrow b perpendicular direction) substantially parallel oblong light beam collimating cylindrical lens for shaping the 14M uniform light intensity, 14C, 14Y and the parallel light beams L _M and L
_It has a convex lens 15 acting on _C and _LY in common to converge their diffusion.

It is needless to say that the shaping optical system 14 is preferably selected, designed, and arranged so that the light beam L does not leak to an extra area, particularly an area that affects the photosensitive material A. The shaping optical system 14 is not limited to the above as long as the shaping optical system 14 can achieve the above object, and various types of lenses, mirrors, and known optical elements such as an optical element combining these can be used. For example, FIG.
As a color exposure device 11 shown in (b), may shaping optical system 14 to each light beam L _M, L _C, a light guide 13M acting respectively L _Y, 13C, also be configured with 13Y. By doing so, the degree of freedom can be given to the layout of the optical system. However, in the exposure apparatus 10 of the present invention, the light beams L _M , L _C , and L _Y emitted from the light sources 12M, 12C, and 12Y respectively correspond to the spatial modulation elements 24M and 24 of the corresponding light modulator 16.
If the entire surface of each of the modulation windows C and 24Y can be sufficiently irradiated, the shaping optical system 14 need not be provided.

The light modulator 16 is a light modulator of the exposure apparatus 10 of the present invention.
It is a characteristic part, and the light beam L _M, L_C, L_YMosquito
According to the digital image signal corresponding to each pixel of the color image
Pulse width by turning on / off (transmitting / shading)
Modulation or pulse number modulation.
Is a light beam L using polarized light._M, L_C, L_YTo
On / off spatial modulation elements 24M, 24C, 24Y
(See FIG. 3). Here, the spatial modulation element 24M,
24C and 24Y are three lights arranged on the light source unit 12 side.
Polarizing plate 36a common to beam L and photosensitive material A side
An analyzing plate 36b common to the three light beams L
It is arranged between the plate 36a and the analyzer plate 36b,
Beam L_M, L_C, L_YLiquid crystal cell provided corresponding to
Arrays 37M, 37C, and 37Y. For use in the present invention
The spatial modulation element used is not particularly limited,
Any spatial modulation element to be used may be used.
However, for example, nematic liquid crystal material, cholesteric liquid
Liquid crystal materials such as crystalline materials and smectic liquid crystal materials,
Preferably smectic C^*Liquid crystal and more preferably
Ferroelectric liquid crystal such as mectic A liquid crystal (FLC; Ferr
oelectoric Liquid Crystal) material and LiNbO
_ThreeSystem, PLZT, LiTaO_ThreeSystems, optical semiconductor materials, etc.
Electro-optic materials using the electro-optic effect can be mentioned.
Wear.

The optical modulator 16 used in the present invention is shown in FIG.
The optical modulator module is composed of a spatial modulator element 24 in which spatial modulators 24M, 24C and 24Y are arranged at predetermined intervals, a pedestal 26 to which the spatial modulator 24 is attached, and a spatial modulator. It has a heat generating module 28 attached to the base 26 together with the modulating element module 24, and a temperature sensor 30 attached to the spatial modulating element module 24 and measuring the temperatures of the spatial modulating elements 24M, 24C, 24Y. Spatial modulation elements 24M, 2
Each of 4C and 24Y has a plurality of, for example, 64 or 512 modulation windows that can be independently modulated in accordance with an image signal for each pixel, and is a so-called multi-channel spatial modulation element having a plurality of, 64 or 512 channels, respectively. Yes, it is possible to record a plurality of pixels, 64 pixels or 512 pixels at a time. Spatial modulation element 24M,
The number of channels 24C and 24Y is not particularly limited, and may be appropriately selected as needed. Here, one pixel is recorded by one spatial modulation element channel, but the present invention is not limited to this, and recording may be performed by a plurality of channels.

Here, the pedestal 26 functions as a fixing member for fixing the spatial light modulating element module 24 and the heat generating module 28 at predetermined positions.
A member that also functions as a heat accumulator (heat accumulator) for controlling the temperatures of the M, 24C, and 24Y, and is formed of a metal plate having high thermal conductivity such as aluminum. In the spatial modulation elements 24M, 24C, and 24Y using an electro-optic material or a liquid crystal, particularly, a smectic A liquid crystal, the response speed, the modulation characteristics, and the transmittance vary depending on the temperature. Therefore, by adopting a configuration in which the pedestal 26 also serves as a heat accumulator, the temperature adjustment using the heat generating module 28 and the temperature sensor 30 can be performed better and more accurately, as described later. The pedestal 26 is provided with through holes for passing the light beams L _M , L _C , and L _Y corresponding to all the modulation windows of the spatial modulation elements 24M, 24C, and 24Y. The details of the spatial light modulator and the light modulator used in the present invention will be described later.

The image forming optical system 18 reduces the size of the image of the modulation window for each channel of the multi-channel spatial modulation elements 24M, 24C, 24Y of a predetermined size so that the image size becomes a pixel size of a desired recording density. A is for forming an image on A, and comprises two lenses 18a and 18b. For example, the recording density of a color image on photosensitive material A is 600 dp.
If i, the size of one pixel is 42.3 μm, and if it is 300 dpi, it is 84.6 μm. Therefore, the image of the modulation window for each channel of the spatial modulation elements 24M, 24C, and 24Y has a recording density of 42.3 at 600 dpi
μm and 300 dpi at 84.6 μm.
The focal lengths of the lenses 18a and 18b may be appropriately selected. In the illustrated example, the imaging optical system 18 is composed of two lenses 18a and 18b, but the present invention is not limited to this.
More than one lens may be used. By the way, it is more preferable to use two or more lens groups than to use one lens in terms of facilitating correction of various aberrations. However, when the number of lenses to be combined increases, the imaging optical system 18 becomes expensive. Therefore, about two lens groups are more preferable.

The optical unit 20 includes a light source section 12 having the three light sources 12M, 12C, and 12Y, a cylindrical lens 14M, 14C, and 14Y and a convex lens 15, and spatial modulation elements 24M, 24C, and 2
4Y, a light modulator 16 having a pedestal 26, a heating module 28, and a temperature sensor 30, and two lenses 18a, 1
The imaging optical system 18 having the lens 8b is attached to or housed in a housing (not shown). The imaging optical system 18 is moved at a predetermined sub-scanning speed in the direction of arrow b by driving means (not shown). What is necessary is just to design and configure suitably according to an optical element. Next, the exposure drum 22 holds the photosensitive material A of a predetermined size in close contact with its outer peripheral surface, and is rotated by a driving unit (not shown) at a predetermined main scanning speed in the direction of arrow a around the center axis as a rotation axis. A known exposure drum of a drum scanner may be used, and its size (radius and length) may be appropriately selected according to the size of the photosensitive material.

The exposure apparatus 10 of the illustrated example is basically configured as described above. Hereinafter, a spatial modulation element characteristic of the present invention and an optical modulator using the same will be described. In the following description, as a representative example of the spatial modulation elements 24M, 24C, and 24Y used in the illustrated exposure apparatus 10, a spatial modulation element that performs pulse width modulation using an optical shutter that uses liquid crystal, and A description will be given of a spatial modulation element including a multi-channel liquid crystal shutter array in which a plurality of modulation windows each having a liquid crystal optical shutter are formed in a direction parallel to the rotation axis of 22, but the present invention is not limited to this. . FIG. 4 shows a conceptual diagram of a structure of an example of the spatial modulation element, and a block diagram of a recording control system and a temperature adjustment control system thereof. Note that the spatial modulation elements 24M, 2
4C, 24Y, the light beam L _M incident, L _C, except that the thickness or total thickness of the liquid crystal layer 32 to be described later are different depending on the wavelength of L _Y, both have the same structure and the same recording control In the case where the same description is given, the spatial modulation element 24C will be described in detail as a representative example, and the other spatial modulation elements 24M and 24Y will not be described. In a representative example of the spatial modulation element 24C,
Since each channel has the same cross-sectional structure,
One channel (modulation window) will be described as a representative example.

The spatial modulation element 24C has a liquid crystal cell 37 in which the liquid crystal layer 32 is sandwiched and sealed between transparent electrodes 34a and 34b, and the liquid crystal cell 37 is sandwiched and corresponds to the transparent electrode 34a on the incident side. Plate polarizer (polarizer) 3
6a, plate-shaped analyzers (analyzers) 36b are arranged corresponding to the emission-side transparent electrodes 34b, respectively, and the laminated bodies are sandwiched between glass plates 38a and 38b. The polarizer 36a is an element that converts the incident light beam L into linearly polarized light, and decomposes the light into two linearly polarized light components that vibrate in directions perpendicular to each other in a plane perpendicular to the light traveling direction and passes the light. . The polarizer 36a
For example, a wave plate, for example, a λ / 2 wave plate can be used. On the other hand, the analyzer 36b is an element for inspecting the presence or absence and the direction of the polarization of the incident light beam L, and the same one as the polarizer is used, and the direction of the polarization of the light beam L incident on the analyzer 36b matches. Used only when the incident light beam L passes. Here, the polarizer 36a and the analyzer 36b
The polarization direction of the light that can pass through is, for example, configured to be different by 90 °, but the present invention is not limited to this, and may be appropriately selected according to the liquid crystal material or electro-optic material used. The transparent electrodes 34a and 34b and the polarizer 36
The a and the analyzer 36b are not particularly limited, and various known devices used for a liquid crystal display, a liquid crystal shutter, and the like can be used.

FIG. 5 conceptually shows the operation of such a spatial modulation element 24C. As described above, the polarization directions of light that can pass through the polarizer 36a and the analyzer 36b are different from each other by 90 °, and when no voltage is applied to the liquid crystal layer 32 by the transparent electrodes 34a and 34b, the polarizer 36a
Since the light beam L that has been linearly polarized by passes through the liquid crystal layer 32 as it is, it is shielded by the analyzer 36b. On the other hand, when a voltage is applied to the liquid crystal layer 32 by the transparent electrodes 34a and 34b, the alignment direction of the liquid crystal changes, and the polarization direction of the light passing through the liquid crystal layer 32 changes as indicated by θ in FIG. Change. That is, the light beam L is applied to the liquid crystal layer 32.
By applying a voltage sufficient to rotate the polarization direction of the light beam 90 by 90 °, the light beam L is
6) can be passed. Therefore, according to the recorded image,
By applying a predetermined voltage to the liquid crystal layer 32 by the transparent electrodes 34a and 34b, the light beam L can be shielded or passed according to a recorded image, and pulse width modulation can be performed. By the way, the spatial modulation element has wavelength dependency, and the transmission efficiency of the incident light beam changes depending on the wavelength.
Therefore, also in the spatial light modulator 24C, the liquid crystal layer 32 or the liquid crystal cell 37, depending on the wavelength λ of the incident light beam L,
Alternatively, it is preferable to set the thickness of the entire spatial modulation element 24C, for example, to set it to an odd or even multiple of the wavelength λ. In the illustrated exposure apparatus 10, three types of light beams L _M , L _C and L _Y having different wavelengths are used as recording light beams, so that the spatial modulation elements 24M, 24C and 24Y are used.
Uses the same liquid crystal material, the incident light beam L _M and the thickness and liquid crystal thickness of the sequence, L _C, it is preferable to use those varied according to the wavelength of L _Y lambda.

In the present invention, as shown in FIG. 3, the spatial modulation element 24C includes a plurality of, for example, 512, transparent electrode pairs 34a and 34b formed in the liquid crystal layer 32 in the illustrated example. The electrode pairs are arranged in the direction of the rotation axis, and are configured to be controllable independently of each other. That is, the spatial modulation element 24C is a liquid crystal shutter array in which 512 (512 channels) independent liquid crystal shutters are arranged. Therefore, the light beam L incident on the spatial light modulating element 24C passes therethrough and is modulated independently by the spatial light modulating element 24C to form 512 independent light beams L _C (L _{C1 to} L _C.
C512 ).

That is, in the exposure apparatus 10 shown in FIG.
12-channel spatial modulation elements 24M, 24C, 24Y
Are used, each of the 512 light beams L _M , L
_C, M in L _Y, C, and simultaneously forming a 512 scanning lines for each color of Y can exposing the photosensitive material A, for example, in the case where one channel corresponds to the image recording of one pixel Can simultaneously record an image of 512 pixels at a time, and can achieve extremely high-speed recording of a color image. According to the exposure apparatus 10 of the illustrated example, compared with the field sequential recording of a color image by one recording light beam by the conventional color exposure apparatus,
A color image can be exposed at a recording speed that is 512 times that of recording a color image by 1536 (3 × 512) times and three combined light beams. Further, the spatial modulation element 2
The light beams L _M , L _C , which have passed through 4M, 24C, 24Y,
Image forming optical system 18 for forming an image of L _Y on photosensitive material A
By adjusting the magnification, focus state, and the like, the spot shapes and intervals of the light beams L _M , L _C , and L _Y formed on the photosensitive material A can be arbitrarily set, and the resolution (recording density) can be easily set. Can be selected to match the system.

Therefore, the exposure apparatus 10 according to the present invention as described above.
According to this method, high-resolution and high-quality color images can be recorded at high speed by multi-channel exposure. In addition, since the number of liquid crystal shutters (the number of channels) of the spatial modulation elements 24M, 24C, and 24Y can be easily set to a desired number, it is possible to easily cope with higher-speed image recording without lowering the resolution. can do. Moreover,
Unlike the conventional light beam scanning exposure, image exposure is not performed by deflection scanning using an optical deflector. Therefore, by selecting the size of the exposure drum 22, it is possible to easily cope with large-sized image recording such as A1 size. be able to.

The spatial modulation element 24 of the exposure apparatus 10 of the present invention
As the liquid crystal used for the M, 24C, and 24Y, various liquid crystals can be used as long as the response speed of the change in the arrangement direction to the application of the voltage sufficiently corresponds to the target recording speed. Typically, ferroelectric liquid crystal (FLC)
The most preferred is a smectic (SMECTIC) liquid crystal, particularly a smectic A liquid crystal (used in the state of smectic A phase). The ferroelectric liquid crystal has an excellent response speed, and generally, the liquid crystal state changes from a smectic C ^* phase to a smectic A phase with an increase in temperature. Here, the ferroelectric smectic C ^* liquid crystal also has a much faster response speed than a liquid crystal display or a nematic liquid crystal usually used for a conventional liquid crystal shutter array, but the ferroelectric smectic A liquid crystal is
A better response speed can be obtained, and the present invention is more suitably used in the present invention for high-speed recording. In addition, since the ferroelectric liquid crystal, particularly the ferroelectric smectic A liquid crystal has a high linearity in the change of the rotation angle of the polarization direction with respect to the applied voltage, the spatial modulation elements 24M, 24
Control of C and 24Y can also be easily performed.

FIG. 6 shows an example of a ferroelectric liquid crystal (M7).
64E; I-Abdulhalim et al. Appl. Phys. Lett. 55 (16), 1
6 October 1989) shows the relationship between the applied voltage and the response speed of the change in the arrangement direction using the temperature of the liquid crystal as a parameter. This ferroelectric liquid crystal becomes a smectic A phase at a temperature above 29 ° C. as a transition point, and becomes a smectic C ^* phase at a temperature lower than that. As is clear from FIG. 6, the smectic C ^* phase has a better response speed than the nematic liquid crystal or the like, but when the smectic A phase (smectic A liquid crystal) is reached, the smectic A ^* phase is nearly two orders of magnitude faster than this. Excellent response speed can be obtained. Moreover, in the smectic A phase, the fluctuation of the response speed with respect to the voltage is extremely small, and a stable operation can be performed.

In the present invention, various known ferroelectric liquid crystals can be used. In particular,
A liquid crystal represented by the following formula [A] or a liquid crystal represented by the above formula [A] is mixed (blended) with a liquid crystal represented by the following formula [B].
Liquid crystal, so-called DO represented by the following formula [C]
BAMBC is exemplified.

[0029]

Embedded image Further, the ferroelectric liquid crystal disclosed in U.S. Pat. No. 5,116,527 can also be suitably used.

The spatial light modulator 24M used in the present invention,
The number of channels of 24C and 24Y is not particularly limited, and may be appropriately determined according to the performance required of the exposure apparatus 10, but is preferably 16 to 512 in order to record a high-resolution image at high speed. The number of channels is approximately, more preferably, approximately 32 to 256 channels. The exposure apparatus 10 in the illustrated example performs pulse width modulation, but the present invention is not limited to this, and may perform pulse number modulation. Further, in the present invention, the rotation angle of the polarization direction of the liquid crystal material or the electro-optic material used for the spatial modulation elements 24M, 24C, 24Y changes according to the applied voltage. the light beam L passing through the analyzer 36b by changing the rotation angle of the polarization direction Te (L _M, L _C, L _Y) to adjust the amount of light may be performed image exposure by intensity modulation. However, in particular, spatial modulation elements 24M and 2M using ferroelectric smectic A liquid crystal are used.
In 4C and 24Y, the light amount control of the light beam L is relatively difficult, and there may be a problem in stability. Therefore, the pulse width modulation or the pulse number modulation is more preferably used in terms of controllability and goodness. . Further, in the exposure apparatus 10 of the present invention, the light beam L is
It is not necessary to completely block light at M, 24C, and 24Y, and the light beam L that does not reach the exposure amount of the lowest density color of the photosensitive material A
May enter the photosensitive material A after passing through the spatial modulation elements 24M, 24C, and 24Y. However, it is not preferable that an extra light beam L is incident on the photosensitive material A, even if the light is of a light amount that does not produce color. Therefore, the unnecessary light beam L is completely removed by the spatial modulation elements 24M, 24C, and 24Y. It is preferable to configure so that light can be shielded from light.

As shown in FIG. 4, the driving system of such a spatial modulation element 24C basically includes an image data conversion correction look-up table (hereinafter simply referred to as a correction LUT) 40, a D / A converter 42, And a driving driver 44 for the spatial modulation element. In the example shown,
Image data from an image data supply source R such as an image reading device is corrected L as digital image data for each channel.
It is supplied to the UT 40. The correction LUT 40 corrects the difference in transmitted light intensity (light amount) for each channel of the spatial modulation element 24C from the digital image data, and exposes the same digital image data to the light beam L passing through each channel. This is for converting the data into exposure amount data to which so-called shading correction is added so that the amount becomes uniform. That is, the correction LUT 40 converts the digital image data into the corresponding correction exposure amount data and, in pulse width modulation, into a digital time width in which a predetermined voltage is applied between the transparent electrodes 34a and 34b of the spatial modulation element 24C. You.

As described above, in the exposure apparatus 10, the shaping optical system 14 converts the light beam L _C into parallel light and makes it incident on all channels of the spatial light modulator 24C. Therefore, due to the distribution of light amount (light intensity) of the light source 12C, the aberration of the shaping optical system 14, the difference in the light beam L _C passing position, etc., the light amount of the light beam L _C incident on the spatial light modulator 24C is completely reduced for all channels. Is not uniform. Also, the spatial modulation element 24
The transmittance and response speed of each channel of C are not completely uniform, and there is a difference even if it is slight. Therefore, even when exposing the photosensitive material A by modulating the recording light beam L _C just as the spatial modulation element 24C, a difference in the exposure amount for each channel occurs, becomes uneven image density.

In order to eliminate such inconveniences, in the illustrated example, an LUT (look-up table) is provided for each channel to absorb the difference in the passing light amount and the response speed for each channel and to eliminate density unevenness. The image data supplied from the image data supply source R is preset and stored in the correction LUT 40, and the image data supplied from the image data supply source R is corrected by the corresponding LUT and converted into appropriate exposure amount (exposure time width) data to eliminate density unevenness. It is possible to obtain a high-quality recorded image. There is no particular limitation on the method of creating the LUT. For example, similarly to a correction table of a known exposure apparatus, a light amount measurement of the light beam L passing through each channel or a density measurement is performed by actually exposing the photosensitive material A. From the results, uniform exposure (recording) according to the supplied image data for each channel
An example is a method of calculating a correction coefficient, a function, and the like that can be used to create an LUT.

The exposure amount (exposure time width) data converted from the image data by the correction LUT 40 is supplied to the D / A converter 4.
The data is converted from the digital exposure amount data into an analog exposure amount (exposure time width) value by 2 and sent to the drive driver 44. Upon receiving the analog exposure value, that is, the exposure time width value, the drive driver 44 applies a predetermined drive voltage to each channel of the spatial modulation element 24C for a time width corresponding to the exposure time width value, and enters the spatial modulation element 24C. thereby modulating the light beam L _C that is in the recorded image.

The transmittance and response speed of the spatial light modulator 24C using liquid crystal are affected by temperature. In particular, in the ferroelectric smectic A liquid crystal suitably used in the exposure apparatus of the present invention, as shown in FIG. 6, the transmittance and the response speed greatly change due to the temperature change. In addition, a normal liquid crystal element is used at normal temperature, but in order to change the state of the ferroelectric liquid crystal to the smectic A phase (preserve the smectic A liquid crystal), it is necessary to set the environmental temperature higher than normal temperature. . Therefore, as shown in FIG. 3 and FIG.
Reference numeral 6 has a temperature adjusting means for keeping the temperature of the spatial modulation element 24C (24M and 24Y) within a predetermined temperature range.

In the optical modulator 16 shown in the figure, the temperature adjusting means of the spatial light modulating element 24C is constituted by the above-mentioned heating module 28, a temperature sensor 30, and a pedestal 26 functioning as a heat accumulator. The device is controlled by a control system including an A / D converter 46, a control device 48, and a driving driver 50 of the heat generating module 28. The heating module 28 used in the present invention is not particularly limited, and various known heating elements can be used as long as they can be heated to an adjusted temperature range or further cooled and have sufficient responsiveness. ,
For example, a power transistor, a thermoelectric cooler (TEC), a Peltier element, and the like are exemplified. In addition, as long as the temperature sensor 30 has sufficient accuracy and responsiveness, various known sensors can be used.
A thermistor, a thermocouple and the like are exemplified.

The temperature of the spatial modulation element 24C detected by the temperature sensor 30 is converted into digital data by the A / D converter 46 and sent to the control device 48. The control device 48 has a temperature control algorithm or an LUT indicating a relationship between the temperature detected by the temperature sensor 30 and the energy supplied to the heat generating module 28, which is set in advance by a known method. The control device 48 includes the spatial modulation element 24
The set temperature PF which is the optimum temperature of C is supplied or stored, the measured temperature data is compared with the set temperature PF, the difference is taken, and the difference is supplied to the heat generating module 28 using the control algorithm or the like. The energy (applied voltage or voltage application time) is determined, and an instruction is issued to the driver 50. The driver 50 supplies the energy according to the instruction from the control device 48 to the heat generating module 28, thereby keeping the temperature of the spatial modulation element 24C constant.

In the present invention, the temperature adjustment range is not particularly limited, and the spatial modulation elements 24C (24M, 24
The temperature may be appropriately set according to the temperature dependency of the characteristic Y), but is preferably about ± 1 ° C., more preferably about ± 0.1 ° C. Further, as described above, in the exposure apparatus 10 of the illustrated example, since the optical modulator 16 and the like are housed in the optical unit 20, the spatial modulator 2
In order to adjust the temperature of 4C (24M, 24Y), it is preferable to adjust the temperature so that the inside of the optical unit 20 is also maintained at a predetermined temperature.

The set temperature is determined by the spatial modulation element 24C (24
M, 24Y), a temperature at which a stable operation can be obtained may be appropriately set according to the liquid crystal material or electro-optical material used in (M, 24Y). For example, as described above, a ferroelectric liquid crystal generally changes its liquid crystal state from a smectic C ^* phase to a smectic A phase due to a rise in temperature, and it is necessary to maintain the smectic A phase at a high temperature of room temperature or higher. However, considering the influence on other optical elements, it is not preferable to set the set temperature too high. On the other hand, if the set temperature is too close to the displacement point, the liquid crystal state may change due to temperature fluctuation. Therefore, the spatial light modulator 24C (24M, 24
When Y) uses a ferroelectric smectic A liquid crystal, the set temperature is preferably such that the liquid crystal state can be stably maintained in the smectic A phase and the temperature is as low as possible ^. It is preferable to set the temperature to about 5 ° C. higher than the displacement point between the phase and the smectic A phase.

In the optical modulator 16 shown in the drawing, one heat generating module 28, one temperature sensor 30, and one temperature control system are provided for the spatial modulation element module 24 having the spatial modulation elements 24M, 24C, and 24Y. Although the temperature is simultaneously adjusted for the three spatial modulation elements 24M, 24C, and 24Y, the present invention is not limited to this, and the temperature is adjusted for each of the spatial modulation elements 24M, 24C, and 24Y or with any two of them. A heating module 28, a temperature sensor 30, and a temperature control system may be provided for the remaining one, and the temperature of the spatial modulation elements 24M, 24C, and 24Y may be adjusted independently or any two and the remaining one may be individually adjusted. . At this time, the base 26 functioning as a heat accumulator for attaching the spatial modulation elements 24M, 24C, 24Y is separated for each of the spatial modulation elements 24M, 24C, 24Y, or for any two and the remaining one. May be.

As described above, such an optical modulator 16
The light beam L modulated according to the recorded image by the (spatial modulation elements 24M, 24C, 24Y) is transmitted to the imaging optical system 1
8, the exposure drum 22 as ₅₁₂ light beams L (for example, L _{C1 to} L C512) having a predetermined size and a predetermined resolution (density), for example, 600 dpi (42.3 μm intervals).
The image is formed on the photosensitive material A held by the image forming apparatus. Exposure drum 22
Is rotating in the direction of arrow a at a predetermined speed about the axis,
At the time when the optical unit 20 makes a predetermined speed in the direction of arrow b parallel to the axis, for example, when the exposure drum 22 makes one rotation,
The next first channel light beams L _M , L _C and L _Y are
A predetermined interval corresponding to a predetermined resolution, for example, 600
At a distance of 42.3 μm according to dpi, the light beam is moved at such a speed as to be adjacent to the scanning line by the light beams L _M , L _C , and L _Y of the previous 512th channel on the downstream side in the direction of arrow b. material a light beam L _M, L _C, is exposed to two-dimensionally over the entire surface by L _Y.

In the exposure apparatus 10 according to the present invention,
And 512 light beams L for each color _M, L_C, L_YFor
Exposure for high-resolution, high-quality color images.
However, stable high-speed color image recording can be performed.
Can be. In the exposure apparatus 10 of the present invention,
Adjust or select the power and refraction characteristics of the imaging optical system 18
Light beam that forms an image on photosensitive material A
L_M, L _C, L_YEach spot shape and size, each beam
And the spacing between channels can be adjusted.
Thereby, it is possible to improve the resolution and the like.

In the exposure apparatus 10 described above, the temperatures of the spatial modulation elements 24M, 24C, and 24Y are detected by the temperature sensor 30, and the heating module 28 is driven in accordance with the detected result to bring the spatial modulation element 24 to a predetermined temperature. I kept it,
The present invention also provides a recording light beam L _M , which has passed through the spatial modulation elements 24 M, 24 C, and 24 Y of the light modulator 16.
At least one of L _C and L _Y is measured by a light amount sensor such as a photodiode, a photomultiplier, or a CCD sensor, and the heat generating module 28 is driven in accordance with the result, and the spatial modulation elements 24M, 24C, 2
4Y may be maintained at a predetermined temperature, or the spatial light modulators 24M and 24M may be corrected by correcting the recording image data of each color according to the measurement result of the light amount sensor described above.
The exposure amounts of the recording light beams L _M , L _C and L _Y by C and 24Y may be configured to be appropriate. As a result, the exposure apparatus of the present invention can record a high-resolution color image stably and at high speed.

[0044] In the embodiments described above, a light source 12M for emitting a light beam L _M for magenta color to record a color image on a color photosensitive material, light beam L for cyan color
A light source 12C that emits _C, light beam L for yellow color
_Although three primary colors of magenta (M), cyan (C), and yellow (Y) are generated using three types of light sources including a light source 12Y that emits Y, the present invention is not limited to this. R), green (G), and blue (B) may be used, or one of the light sources that emit these three primary colors of R, G, and B, for example, green (G) may be used. When the light amount of the light source is insufficient for the color photosensitive material to be recorded, two light sources that emit green (G) may be used to emit green (G) at a predetermined density. That is, in the present invention, even if the number of light sources is increased, it can be easily coped with only by increasing the number of light beam cylindrical lenses and spatial modulation elements. When using, by using a plurality of light sources, without increasing the size of the device configuration too much,
It is possible to easily cope with insufficient light quantity.

As described above, the color exposure apparatus of the present invention has been described in detail with reference to the various embodiments described above. However, the present invention is not limited to these embodiments. Of course, various improvements and changes may be made. For example, the above-mentioned color exposure apparatus
Although the configuration has one optical unit, the present invention is not limited to this. The configuration is such that a plurality of optical units are arranged corresponding to the rotation direction of the exposure drum, and exposure is performed simultaneously by the plurality of optical units. May be.

[0046]

As described above in detail, according to the present invention, a multi-channel color printer having a high productivity, an inexpensive and simple structure capable of recording a color image on a large-size color photosensitive material at a high speed. An exposure apparatus can be provided. In the present invention, a spatial modulator using a ferroelectric liquid crystal, particularly preferably a ferroelectric smectic A liquid crystal, is used to perform multi-channel exposure with a simple and inexpensive structure to achieve high resolution and high resolution. High-quality color images can be recorded at high speed.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an embodiment of a color exposure apparatus according to the present invention.

2A is a schematic configuration diagram of the color exposure apparatus shown in FIG. 1, and FIG. 2B is a schematic configuration diagram of another embodiment of the color exposure apparatus according to the present invention.

FIG. 3 is a schematic perspective view of one embodiment of a light modulator module of the color exposure apparatus shown in FIG.

4 is a schematic configuration diagram of a spatial modulation element of the color exposure apparatus shown in FIG. 3 and a block diagram of a drive control system and a temperature control system thereof.

FIG. 5 is a schematic perspective conceptual view for explaining the operation of the spatial light modulator shown in FIG.

6 is a graph showing the relationship between the applied voltage and the response speed of a ferroelectric smectic A liquid crystal used in the spatial light modulator shown in FIG.

FIG. 7 is a graph showing an example of spectral sensitivity characteristics of a color photosensitive material used in the color exposure apparatus of the present invention.

[Explanation of symbols]

10, 11 color exposure apparatus 12 light source unit 12M, 12C, 12Y light source 13M, 13C, 13Y light guide 14 shaping optical system 14M, 14C, 14Y cylindrical lens 15 convex lens 16 optical modulator 18 imaging optical system 18a, 18b lens 20 optical Unit 22 Exposure drum 24 Spatial modulation element module 24M, 24C, 24Y Spatial modulation element 26 Pedestal 28 Heating module 30 Temperature sensor 32 Liquid crystal layer 34a, 34b Transparent electrode 36a Polarizer 36b Analyzer 37 Liquid crystal cell 37M, 37C, 37Y Liquid crystal cell array 38a , 38b glass plate 40 image data correction LUT (look-up table) 42 D / A converter 44 driver 46 A / D converter 48 the control device 50 driver A color light-sensitive material L, L _M, L _{C, Y} light beam

Claims (4)

[Claims] 1. A plurality of light sources for emitting light beams having different narrowband wavelengths, a light beam shaping optical system for shaping light beams emitted from these light sources, and a plurality of light sources corresponding to the plurality of light sources, respectively. A plurality of spatial light modulators, each of which modulates each light beam shaped by the light beam shaping optical system in accordance with an image signal to be recorded, and a color light beam modulated by these spatial light modulators. A reduction optical system configured to reduce and form an image on a material; and a scanning unit configured to two-dimensionally scan the color photosensitive material with a plurality of modulated light beams formed by the reduction optical system. Color exposure equipment. 2. The color exposure apparatus according to claim 1, wherein said spatial modulation element is a multi-channel spatial modulation element having a plurality of modulation windows that are independently modulated. 3. The color exposure apparatus according to claim 1, wherein said spatial modulation element has a temperature control means. 4. A color exposure apparatus according to claim 1, wherein at least two of said light sources emit light beams for emitting the same light.