JP2002090918A - Exposure device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an exposure device which is capable of forming high-quality full-color images. SOLUTION: This image exposure device forms full-color images by focussing the light rays of respective colors R, G and B time sequentially emitted from respective optical shutter elements 33 of an optical shutter array consisting of a PLZT chip 32 onto photosensitive paper 5 by a monofocal lens array 45. A prism 46 is installed on the exit surface side of the monofocal lens array 45. This prism 46 varies the exposure positions of the respective light rays of R, G and B emitted from the lens array 45 and exposes the respective light rays constituting one pixel onto a fixed position on the photosensitive paper 5 moving at a constant speed in a sub-scanning direction A.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus,
The present invention relates to an exposure apparatus for turning an optical shutter element such as a PLZT or the like and a light emitting element such as an LED on and off based on image data to form an image on a recording medium.

[0002]

2. Description of the Related Art Conventionally, as a print head used for high-quality image formation such as a digital copying machine, an electrophotographic optical printer, and an image forming apparatus for silver halide photosensitive paper, light having an electro-optical effect such as PLZT is used. Various exposure apparatuses using a light emitting element such as a shutter element or an LED as a light control element have been provided.

For example, in the case of an exposure apparatus using a PLZT optical shutter array, a pulse signal corresponding to image data is applied to each optical shutter element to emit light, and the emitted light is projected onto a recording medium by a single focus lens array. Make an image. The optical shutter elements are linearly arranged (hereinafter, referred to as a main scanning direction), and the recording medium is moved at a constant speed in a direction perpendicular to the main scanning direction (hereinafter, referred to as a sub-scanning direction). A two-dimensional image is formed on the recording medium.

In this type of exposure apparatus, a full-color image is formed by switching the color of illumination light from an optical shutter element in time sequence according to the color development characteristics of a silver halide photosensitive paper as an object to be exposed. are doing.

In such an exposure apparatus, the photosensitive paper moves at a constant speed in the sub-scanning direction and is sequentially exposed with the three primary colors of light, R, G, and B. Therefore, as shown in FIG. , R, G, and B are exposed at equal intervals during one pixel pitch P, and cannot be exposed at the same position. That is,
One pixel image that should be exposed at the same position is R, G,
There is a problem that the image quality is degraded for each B, and the quality of the image is deteriorated. Such a problem is more remarkable in a high-end machine which forms an image with high specifications.

Accordingly, an object of the present invention is to obtain a high-quality image, and particularly to form a R,
An object of the present invention is to provide an exposure apparatus capable of obtaining a high-quality image by eliminating the shift of each pixel of G and B.

[0007]

In order to achieve the above object, an exposure apparatus according to the present invention comprises a light control element in which a plurality of light control elements for turning on and off a plurality of lights having different wavelengths are linearly arranged. An array, a single focus lens array that forms an image of light emitted from the light control element on an object to be exposed, and different exposure positions of light of each wavelength emitted from the single focus lens array in the sub-scanning direction. An optical element.

In the exposure apparatus according to the present invention having the above-described configuration, since the exposure positions of the light beams of the respective wavelengths are made different in the sub-scanning direction, substantially the same position on the object to be exposed moving at a constant speed in the sub-scanning direction. , And as a result, almost the same image can be formed as one pixel with light of each wavelength.

In particular, in the exposure apparatus, the light control element emits red, green and blue light, which are the three primary colors of light, at regular intervals in synchronization with the moving speed of the object to be exposed in the sub-scanning direction. A full-color image can be formed with high quality. Further, the present invention can be preferably applied to an exposure apparatus in which the light control element is made of a material having an electro-optical effect.

In the exposure apparatus according to the present invention, if a prism is used as the optical element, the exposure position of each wavelength light can be made different in the sub-scanning direction with a simple configuration. If the installation position of the prism in the optical axis direction can be adjusted, the exposure interval of light of each wavelength can be finely adjusted.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an exposure apparatus according to the present invention will be described below with reference to the accompanying drawings.

(Schematic Configuration of Image Forming Apparatus, See FIG. 1) FIG. 1 shows an image forming apparatus provided with an exposure apparatus 1 according to an embodiment of the present invention. Denotes a chemical processing unit, and 15 denotes a paper discharge tray. Exposure device 1
Is composed of a light source unit 2 and a recording head 3, the details of which will be described below. The silver halide photosensitive paper 5 is set in a roll state in the storage section 6, is sequentially pulled out by a transport roller 7 and the like, and is transported at a constant speed in the direction of arrow A (sub-scanning direction). To form a latent image.

The silver halide photosensitive paper 5 on which the latent image is formed is sent to a chemical processing unit 10 where development / fixing / cutting is performed.
1 are sequentially stored on the tray 15.

(Exposure Apparatus, see FIGS. 2 to 5) Next, the exposure apparatus 1 will be described with reference to FIGS. Light source 2
Is composed of a halogen lamp 21, a heat insulating filter 22, a color correction filter 23, a light diffusion tube 24, and a color filter 25. The recording head 3 generally includes an optical fiber array 26, a slit plate 27, an optical shutter module 30, an imaging lens array 45, and a dustproof glass 47.

The color filter 25 is composed of three filters equally divided in the circumferential direction for transmitting the three primary colors of light, R, G, and B, at a constant speed, that is, one filter by the optical shutter module 30. The rotation is driven in synchronization with the writing operation for each color.

The optical fiber array 26 is formed by bundling a number of single optical fibers. One end 26a is bundled and faces the light source unit 2. The other end 26b is arranged linearly in the main scanning direction indicated by the arrow B, and emits light in a line.

As shown in FIG. 3, the optical shutter module 30 is provided with a plurality of optical shutter chips 32 made of PLZT on a substrate 31 (on a slit opening of a ceramic substrate or on a glass substrate) to form an array 38. In addition, a driving IC 39 is provided on the substrate 31 side by side with the chip 32.

As shown in FIG. 4, a number of light shutter elements (light control areas) 33 for turning on / off light corresponding to one pixel are formed in each light shutter chip 32, and a common electrode 34 and each light shutter element 33 are formed. An individual electrode 35 corresponding to the element 33 is provided. The optical shutter elements 33 are arranged in a staggered manner in two rows, and form one line of image in the main scanning direction B in two rows. By the main scanning and the sub-scanning of the photosensitive paper 5, a two-dimensional image is formed on the photosensitive paper 5.

Further, a polarizer 41 and an analyzer 42 are provided before and after the optical shutter module 30 (see FIG. 2). As is well known, PLZT is a translucent ceramic having a large Kerr constant and having an electro-optic effect, and the light linearly polarized by the polarizer 41 is applied to each element 33.
The rotation of the plane of polarization is caused by the electric field generated by applying a voltage to the light source, and the light emitted from the analyzer 42 is turned on and off.

The light emitted from the analyzer 42 passes through an imaging lens array 45 and a prism 46, which will be described below, and further through a dustproof glass 47, and forms an image on the photosensitive paper 5 in the exposure unit 9 to form a latent image. To form

(Imaging lens array and prism, FIG. 5,
6) The imaging lens array 45 is composed of a plurality of single-focal lenses having an erecting equal-magnification imaging function arranged in the main scanning direction. As the single-focal lens, for example, SELFOC (trade name: Japan) Plate glass) can be used.

As shown in FIG. 5, the prism 46 has a right-angled triangular cross section, and is generally made of BK7 as optical glass.
And is provided on the exit surface side of the imaging lens array 45. The light emitted from the imaging lens array 45 is exposed on the photosensitive paper 5 by the prism 46 by changing the optical path in the sub-scanning direction at a refractive index corresponding to the wavelength for each of R, G, and B colors. Specifically, the refractive index of the prism 46 is larger for blue light having a shorter wavelength, and R, G, B at intervals shown in FIG.
Are different in exposure position.

Exposure is performed by the color filter 25 described above.
As shown in FIG. 6, switching is performed in synchronization with the moving speed of the photosensitive paper 5 in the sub-scanning direction in the time sequence of R, G, and B. Then, R, G, and B lights are sequentially exposed to the same position on the photosensitive paper 5 that moves at a constant speed in the sub-scanning direction. FIG. 7 shows such an exposure state, in which exposure of R, G, and B constituting one pixel is performed at the same position on the photosensitive paper 5 in the sub-scanning direction. In FIG. 7, a symbol P indicates a pitch of one pixel in the sub-scanning direction.

The installation position of the prism 46 is indicated by an arrow C
Can be adjusted in the direction of the optical axis. Prism 46
By changing the position in the direction of the optical axis, the intervals between the exposure positions of R, G, and B are finely adjusted.

As described above, in the present exposure apparatus 1, the exposure position of the light emitted from the imaging lens array 45 is changed for each wavelength by using the prism 46, and the exposure position is changed to the same position on the photosensitive paper 5. Since the exposure is performed, each color of R, G, and B can be formed without shifting in one pixel, and a high-quality full-color image can be obtained.

(Other Embodiments) The exposure apparatus according to the present invention is not limited to the above embodiment, but can be variously modified within the scope of the invention.

In particular, the details of the light source section or the recording head of the exposure apparatus are arbitrary. Further, as the light control element, a material having an electro-optical effect other than the PLZT described in the above embodiment or a liquid crystal, or a light emitting element such as an LED or a fluorescent display tube can be used.

The prism may not be provided independently of the imaging lens array, but may be integrated into the imaging lens array. Further, as an optical element for changing the optical path, any element having an equivalent function other than the prism can be used.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an image forming apparatus provided with an exposure apparatus according to the present invention.

FIG. 2 is a perspective view showing an embodiment of an exposure apparatus according to the present invention.

FIG. 3 is a front view showing an optical shutter module incorporated in the exposure apparatus.

FIG. 4 is a perspective view showing an optical shutter chip constituting the optical shutter module.

FIG. 5 is an explanatory view showing an exposure state by the exposure apparatus.

FIG. 6 is a chart showing a switching state of R, G, and B light by the exposure apparatus.

FIG. 7 is a graph showing an exposure amount on an object to be exposed by the exposure apparatus.

FIG. 8 is a graph showing an exposure amount on an object to be exposed by a conventional exposure apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Exposure apparatus 30 ... Optical shutter module 32 ... Optical shutter chip 33 ... Optical shutter element 38 ... Optical shutter array 45 ... Imaging lens array 46 ... Prism

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C162 AE28 FA09 FA36 FA44 FA49 FA54 FA59 FA67 2H106 AB04 BA55 BH00 2H110 CC03 CD17 CE03

Claims (6)

[Claims] 1. A light control element array in which a plurality of light control elements for turning on and off light having different wavelengths are linearly arranged, and light emitted from the light control elements is imaged on an object to be exposed. An exposure apparatus, comprising: a single-focus lens array for causing the laser beam to emit light of each wavelength emitted from the single-focus lens array; 2. The light control element according to claim 1, wherein the light of three primary colors of light, red, green, and blue, is switched at regular intervals in synchronization with the moving speed of the object in the sub-scanning direction and emitted. The exposure apparatus according to claim 1, wherein 3. The exposure apparatus according to claim 2, wherein the optical element exposes the red, green, and blue light to substantially the same position as the object to be exposed moves in the sub-scanning direction. 4. The exposure apparatus according to claim 1, wherein the light control element is made of a material having an electro-optic effect. 5. The exposure apparatus according to claim 1, wherein the optical element is a prism. 6. An exposure apparatus according to claim 5, wherein said prism can adjust an installation position in an optical axis direction.