JPH11271892A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of reducing the influence of chromatic aberration and obtaining a focused image with reference to every color, irrespective of a simple mechanism. SOLUTION: As for the image forming device for forming a color image by forming an image on a photosensitive material with plural kinds of light having different wavelength through a single image forming optical system arranged in array and exposing the image, a transparent member 18 whose refractive index on the short wavelength side is made larger than that on a long wavelength side is arranged on an optical path between the image forming optical system 17 and the photosensitive material. And, as for an optical path from the image forming optical system 17 to the photosensitive material as an image forming surface, there is an optical path difference between the short wavelength side light and the long wavelength light then, by making the expansion of the optical path of the short wave length side light larger than that of the optical path of the long wavelength side light, the difference between the optical paths up to the image forming surface is reduced as small as possible, then, the focused image of high quality is obtained with reference to every color.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus for forming a color image on a photosensitive material by a single imaging optical system.

[0002]

2. Description of the Related Art Conventionally, to form a color image,
It was common to use at least three printheads for red, green and blue exposure,
When each of the red, green, and blue lights is exposed using a single imaging optical system, an image can be formed with a single print head simply by replacing color filters in principle.

[0003] In particular, when a PLZT array print head is used as an exposure system, a large cost reduction effect can be expected, and this is also useful for making the entire system compact.

[0004]

However, when an image is to be exposed by such a method, since light beams having different wavelengths pass through the same optical system, an image forming position on a photosensitive material is different for each color having a different wavelength. On the other hand, there is a problem that the specific color is in focus but the other colors are not in focus, resulting in deterioration of image quality.

As a solution to the above problem, it has been attempted to provide a mechanism for moving the imaging optical system closer to or farther from the photosensitive material for each exposure color. This has led to difficulties.

In particular, in a system in which a plurality of light beams having different wavelengths are imaged on a photosensitive material via recording elements arranged in an array to perform exposure, a selfoc lens array (manufactured by Nippon Sheet Glass Co., Ltd.) Since the use of an imaging optical system having a small aperture angle, such as a rod lens array, is indispensable, the problems described above have become remarkable, and their solutions have been urgently required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an image forming apparatus capable of reducing the influence of chromatic aberration with a simple mechanism and obtaining images in which each color is in focus. And

[0008]

In order to achieve the above object, the present invention provides a method of forming a plurality of light beams having different wavelengths on a photosensitive material through a single imaging optical system arranged in an array.
In an image forming apparatus that forms a color image by performing exposure, a transparent member whose refractive index on the short wavelength side is larger than that on the long wavelength side is disposed on an optical path between the imaging optical system and the photosensitive material. The optical path from the imaging optical system to the photosensitive material serving as the imaging surface has a difference in the light path on the short wavelength side and the light on the long wavelength side. By making it larger than the extension of the optical path on the side, the difference in the optical path to the image plane is made as small as possible, so that a high-quality image in which each color is in focus is obtained.

The invention according to claim 2 is characterized in that the transparent member has a flat plate structure parallel to the image forming surface of the photosensitive material, and is arranged in an array and has a small aperture angle. The configuration is such that it is not necessary to dispose an optical system individually for each system, and simplification of manufacturing and adjustment can be achieved.

Further, the invention according to claim 3 is characterized in that the transparent member also serves as a regulating member for regulating the deformation of the image forming surface of the photosensitive material, and prevents the photosensitive material from being deformed at the exposure position. The system is configured so that the out-of-focus state that occurs when raised can be suppressed.

Further, the invention according to claim 4 is characterized in that the image formation is performed by controlling the amount of light by controlling the PLZT, so that the image formation can be speeded up.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 is a schematic cross-sectional view of an image printer to which the present invention is applied, FIG. 2 is a schematic perspective view of an enlarged optical recording system, and FIG. 3 is a flat transparent plate between an imaging optical system and a photosensitive material. FIG. 4 is an explanatory view showing the apparatus of the present application in which members are installed, FIG. 4 is an explanatory view showing a state in which deformation of the photosensitive material is suppressed at an exposure position between transport rollers, and FIG. FIG. 4 is an explanatory diagram of a comparative example showing a state where the occurrence of the phenomena.

Image printer body 1 to which the present invention is applied
Is a silver halide color photosensitive material (photographic paper) 4 drawn out of the photographic paper magazine 2 by the transport means 3 as shown in FIG.
Then, the image information captured by the scanner 5 is recorded by the optical recording system 6, and then is transported to the development processing unit 7 for development processing, cut to a predetermined size by the cutter 8, and It is configured so that it can be discharged to In addition,
Needless to say, the cutting may be performed before the sheet is conveyed to the development processing section 7 and further before the sheet is conveyed to the optical recording system 6.

As shown in FIG. 2, the optical recording system 6 transmits light K which is transmitted from a light source system (white light source) 10 through a rotary color filter 11 to an input unit 13 of a light transmission system (optical fiber) 12. Is guided to a print head (recording element array section) 14 through an optical fiber 12 and is exposed to the photosensitive material 4 via a single rod lens array (imaging optical system) 17.

The exposure is performed on the photosensitive material 4 transported in the direction of the arrow by transport rollers 3a and 3b rotating in connection with a drive source (not shown). The exposure of the color filter 11 is controlled in accordance with the R, G, and B values of the image data in accordance with commands from the image output control unit 15 and the filter switching control unit 16. When the exposure process is completed, as described above, the photosensitive material 4 is transported to the developing unit 7 and undergoes a predetermined developing process to obtain an output image.

The print head 14 includes a plurality of PLZT shutter elements arranged at 300 dpi in a row and a rod lens array (imaging optical system) 1.
7, which is particularly effective for increasing the recording speed.

Although the photosensitive material 4 has been described in the form of a roll, it may be cut paper from the beginning of paper feeding. The transport means 3 for the photosensitive material 4 is not limited to the transport rollers 3a and 3b shown in FIGS. further,
A method in which the photosensitive material 4 is fixed and the print head 14 moves, or a method in which the photosensitive material 4 and the print head 14 move together may be used.

When the rod lens array 17 is used as the imaging optical system, there is an advantage that it is possible to contribute to the realization of miniaturization and cost reduction of the whole apparatus. However, the present invention is not limited to this. Of course, it may be used.

Although the recording operation has been described as an example of an array in which the PLZT shutter elements employed in the print head are arranged in a single row, an array in which a plurality of recording elements are arranged or an array in which a two-dimensional panel is arranged may be used. By appropriately setting the timing with the recording position on the photosensitive material and performing exposure control, a color image can be recorded.

Further, as another embodiment of the present invention, the same effect can be obtained even when performing image recording by combining another optical shutter element such as a liquid crystal shutter array.

The rod lens array (imaging optical system) 1
A transparent member 18 is provided on the photosensitive material 4 on the optical path between the photosensitive material 4 and the photosensitive material 4 as shown in FIG. This transparent member 1
8 is used under the condition that the refractive index on the short wavelength side is larger than the refractive index on the long wavelength side.

The difference between an optical path (shown by a broken line) A 'on the short wavelength side from the image forming optical system 17 to the photosensitive material 4 to be an image forming surface and an optical path (shown by a broken line) B' on the long wavelength side ( ΔL ₁ ) is increased, but by providing the transparent member 18 under the above conditions on the optical path between the imaging optical system 17 and the photosensitive material 4,
By making the focal length of the light path A on the short wavelength side (shown by a solid line) longer than that of the light path B on the long wavelength side (shown by a solid line), the difference in the optical path to the photosensitive material (imaging plane) 4 is increased. (Δ
L ₂ ) is made as small as possible, and a high-quality image in which each color is in focus can be obtained.

As the transparent member 18 satisfying the above conditions,
In addition to general transparent glass plates, transparent acrylic resin plates, and other commercially available products having a low Abbe number, commercially available products, and special optical systems such as concave lenses and cylindrical lenses can also be used.

The wavelength region from short wavelength to long wavelength used for image recording is preferably a visible light region, because it is possible to use color paper generally used as a photosensitive material as it is. Specifically, image recording is performed using light in the blue, green, and red wavelength regions.

The transparent member 18 preferably has a flat plate structure parallel to the image forming surface of the photosensitive material 4. That is, it is not necessary to arrange optical systems such as concave lenses individually corresponding to the individual rod lenses of the rod lens array constituting the imaging optical system having a small aperture angle arranged in an array,
This is because the simplification of manufacturing and adjustment can be achieved because one transparent member 18 can be used.

The transparent member 18 is formed as shown in FIG.
It is desirable to install the photosensitive material 4 in the vicinity of the conveyance path because the photosensitive material 4 can also serve as a regulating member for regulating the deformation of the image forming surface of the photosensitive material 4. That is, the photosensitive material 4 is transported by the conveying rollers 3a, 3
b, but since there is no support means at the exposure position corresponding to the irradiation surface of the imaging optical system 17, the photosensitive material 4 deforms at the exposure position such as floating as shown in FIG. There is a possibility that a defocus may occur as a result of the occurrence, but the above configuration can suppress this phenomenon before it occurs.

The distance between the regulating member 19 on the side opposite to the exposure and the transparent member 18 is such that the photosensitive material 4 can be conveyed without requiring excessive force, that is, the photosensitive material 4
It is preferable to set the interval slightly larger than the thickness from the viewpoints of deformation suppression and transportability.

[0028]

Example 1 Using one PLZT array print head, rotating a color filter on a disk composed of a red part (R), a green part (G), and a blue part (B),
An image forming apparatus for performing exposure recording in the order of G and B is prepared, and between the image forming optical system 17 and the photosensitive material (silver halide color photosensitive material) 4 as shown in FIG. A flat transparent member (flat glass; n _R <n _G <
n _B [n _R is a bending rate with respect to the wavelength of the R light, n _G is a bending rate with respect to the wavelength of the G light, and n _B is a bending rate with respect to the wavelength of the B light. ]) Was inserted. As a result, the spread of the green light exposure spot, the red light exposure spot, and the blue light exposure spot was reduced, and a good image output result with a large degree of overlap and a small color shift was obtained.

[0029]

As described above, according to the present invention, a plurality of light beams having different wavelengths are imaged on a photosensitive material through a single imaging optical system arranged in an array, and exposure is performed to form a color image. In the image forming apparatus to be formed, on the optical path between the imaging optical system and the photosensitive material, a transparent member having a refractive index on the short wavelength side larger than that on the long wavelength side is provided. Therefore, light on the short wavelength side and light on the long wavelength side, where the optical path from the imaging optical system to the photosensitive material serving as the imaging surface has a difference,
By making the elongation of the optical path on the short wavelength side larger than the elongation of the optical path on the long wavelength side, a high-quality image in which each color is focused by minimizing the difference in the optical path to the image plane, that is, An excellent effect is obtained in that the disturbance to the sharpness of the recorded image can be suppressed and the disturbance to the color shift can be remarkably improved.

Further, the invention according to claim 2 is characterized in that the transparent member has a flat plate structure parallel to the image forming surface of the photosensitive material. This eliminates the need to dispose optical systems individually for each of the image optical systems, and achieves an excellent effect that simplification of manufacturing and adjustment can be achieved.

Furthermore, the invention according to claim 3 is characterized in that the transparent member also serves as a regulating member for regulating the deformation of the image forming surface of the photosensitive material. An excellent effect is achieved in that the out-of-focus generated when the deformation occurs can be suppressed.

Further, the invention according to claim 4 is characterized in that image formation is performed by controlling the amount of light by controlling the PLZT, and has the effect that the speed of image formation can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an image printer to which the present invention is applied.

FIG. 2 is an enlarged schematic perspective view of an optical recording system.

FIG. 3 is an explanatory view showing the apparatus of the present application in which a transparent member made of a flat plate is provided between an imaging optical system and a photosensitive material.

FIG. 4 is an explanatory diagram showing a state where deformation of a photosensitive material is suppressed at an exposure position between conveyance rollers.

FIG. 5 is an explanatory diagram of a comparative example showing a state in which a photosensitive material is deformed at an exposure position between conveyance rollers.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image printer main body 2 Printing paper magazine 3 Conveying means 3a, 3b, drive roller 4 Recording medium (silver halide color photosensitive material) 5 Scanner 6 Recording head 7 Development processing part 8 Cutter 9 Discharge tray 10 Light source system (white light source) DESCRIPTION OF SYMBOLS 11 Color filter 12 Optical transmission system (optical fiber) 13 Optical fiber input part 14 Print head (recording element array part) 15 Image output control part 16 Filter switching control part 17 Imaging optical system (rod lens array) 18 Transparent member 19 Opposite exposure Surface regulating member K Light A Between the imaging optical system and the photosensitive material Light path on the short wavelength side in the case of a transparent member dovetail B Optical path on the long wavelength side Same as between the imaging optical system and the photosensitive material optical path B 'same, the optical path [Delta] L ₁ a long wavelength side' of the short wavelength side when the transparent member without the B 'and the difference (large) [Delta] L ₂ a of the optical path of the B The difference of the optical path (small)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI G03B 27/50 G03B 27/50 D (72) Inventor Shoichi Nomura 1 Sakuracho, Hino City, Tokyo Konica Corporation

Claims (4)

[Claims] A plurality of light beams having different wavelengths are imaged on a photosensitive material through a single imaging optical system arranged in an array;
In an image forming apparatus that forms a color image by performing exposure, a transparent member whose refractive index on the short wavelength side is larger than that on the long wavelength side is disposed on an optical path between the imaging optical system and the photosensitive material. An image forming apparatus, comprising: 2. The image forming apparatus according to claim 1, wherein the transparent member has a flat plate structure parallel to an image forming surface of the photosensitive material. 3. The image forming apparatus according to claim 1, wherein the transparent member also serves as a regulating member that regulates deformation of an image forming surface of the photosensitive material. 4. The image forming apparatus according to claim 1, wherein the image formation is performed by controlling the amount of light by controlling the PLZT.