JPH0545997A - Image forming device - Google Patents

Abstract

PURPOSE:To provide the image forming device being structurally simple and compact where a pre-proof, especially a color pre-proof, can be produced directly from digitized image signal with ease and good operability. CONSTITUTION:The device is equipped with an exposure drum 12 on which a photosensitive layer 11 is provided on the outer periphery where a latent image or a visual image of (n) colors can be formed at a specified spacing, an exposure device 16 by which the image is exposed onto the photosensitive layer, developing devices 18 for n colors by which the photosensitive layer after exposure is developed, and a transfer roll 20 having 1/n diameter of the exposure drum 1, and one sheet of image reception paper is wound, transferring the certain color image formed on the exposure drum with one rotation, while in contact with the exposure drum directly or through an intermediate transfer body, and then, the image reception paper on which the images of n colors are formed is discharged after the images of n colors are transferred on the image reception paper with continuous rotation for n times of the transfer roll.

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,
Specifically, in an electronic plate making system applied to an electronic publishing system, a desktop publishing (DTP) system, etc., a color proof can be easily produced directly from an image signal converted into an electric signal, and the structure is simple and compact. Moreover, the present invention relates to an image forming apparatus capable of producing a high-quality color proof.

[0002]

2. Description of the Related Art With the spread of electronic plate making systems called layout scanners and total scanners, a proofreading machine or a proofing plate made in the same manner is used in a manufacturing process of printed matter to which the electronic plate making system is applied. Instead of proof printing using ink with a printing machine, so-called DDCP (Direct Digital Color Proofin)
Color proof according to g) is applied.

The DDCP is a method for directly producing a color proof from digital data for plate making without using a film such as a lith film.

Conventionally, as a plate making method which simplifies the work, computerization (CTS: Computer Type Setting System) of phototypesetting and typesetting, which has been conventionally performed by humans, and input of characters and charts are performed by a word processor. Computerization of not only electronically, but also plate making and layout of photographs using electronic plate making machines and layout scanners, etc., electronic publishing in which various processes from printing to publishing or all processes are managed by computer Has been. Further, electronic publishing has been promoted as a compound terminal such as a desk top publishing (DTP) in which a word processor, a personal computer, a facsimile, a copying machine, a telephone, and a communication function are integrated. In such electronic publishing and DTP, it is possible to use a plate-making film by digitizing the plate making of the printing original plate, or not.
An electronic plate-making system that simplifies the process and speeds up is used.

In the DDCP, digital data of a plate-making image in such an electronic plate-making system is subjected to image processing to form a full-color visible image according to the image data on a light-sensitive material or an image-receiving material to produce a color proof. The produced color proof is applied to various kinds of inner and outer schools in plate making work, and various uses such as a swatch for printing.

By the way, as an image forming apparatus applied to such a DDCP, a color image forming apparatus applying a silver salt photographic light-sensitive material, a transfer image forming apparatus applying a sublimation type heat-sensitive recording material, an ink jet method is used. A drawing image forming apparatus and a toner image forming apparatus using electrostatic recording electrophotography are mainly applied.

For example, as a toner image forming apparatus for electrostatic recording electrophotography applied to DDCP, one having the following configuration is known.

This device is basically an electrophotographic image forming device to which so-called raster scanning is applied, and is a laser for processing digital image information input to the image processing device and carrying plate-making image information. This laser beam exposes an exposure drum having an electrophotographic photosensitive material arranged on the outer periphery thereof with a laser beam to form an electrostatic latent image on the exposure drum (electrophotographic photosensitive member).

A four-color rotary developing mechanism and a transfer drum are provided in contact with the exposure drum. The four-color rotary developing mechanism has a developing device for developing each of BK (black), C (cyan), M (magenta), and Y (yellow) toner so that the outer circumference thereof is divided into four equal parts in the circumferential direction. It has a cylindrical shape and is rotated by 90 ° with development of each color, and the electrostatic latent images sequentially formed on the electrophotographic photosensitive member are developed with toner.

The transfer drum is disposed on the downstream side of the four-color rotary developing mechanism in contact with the exposure drum with respect to the rotation direction of the exposure drum, holds the image-receiving paper, and contacts the exposure drum at a predetermined pressure. It rotates at the same peripheral speed as the drum,
The toner image formed on the exposure drum is transferred to the image receiving paper held on the transfer drum. In this manner, BK, C, M, and Y are sequentially transferred onto the image receiving paper held on the transfer drum to form a full-color image on the image receiving paper.

The formation of a full-color image in this toner image forming apparatus is specifically carried out as follows. A laser beam carrying image information is deflected in the main scanning direction, and a uniformly charged exposure drum rotating in a sub scanning direction substantially orthogonal to the main scanning direction is two-dimensionally scanned,
Form an electrostatic latent image. Here, if the developing devices provided in the four-color rotary developing mechanism are in the order of BK, C, M, and Y from the upstream side in the rotation direction of the four-color rotary developing mechanism, first, the C image on the exposure drum is A latent image is formed.

When the exposure drum rotates and the portion where the electrostatic latent image is formed comes into contact with the C image developing device of the four-color rotary developing mechanism, this electrostatic latent image is toner-developed to form a C toner image. It When the exposure drum rotates further, this C
The toner image comes into contact with the transfer drum holding the image receiving paper and is transferred to the image receiving paper.

On the other hand, when the formation of the electrostatic latent image of the C image on the exposure drum is completed, the electrostatic latent image of the M image is continuously formed, and similarly, toner development is performed to form the M toner image, which is transferred. It is transferred onto the C toner image on the image receiving paper held on the drum.

Similarly, the Y toner image and the BK toner image are further transferred onto the image receiving paper, and finally a full color image consisting of BK, C, M and Y is formed on the image receiving paper. The toner images thus formed on the exposure drum are sequentially transferred to the image receiving paper to form a color proof.

Further, after forming a full-color image of BK, C, M, and Y on an exposure drum having an electrophotographic photosensitive member mounted on the outer periphery, this color image is transferred to an image receiving paper via a transfer material to transfer a color image. An apparatus for making a proof has also been proposed.

In this apparatus, similarly to the previous apparatus, after forming an electrostatic latent image corresponding to, for example, C image on the uniformly charged exposure drum, this image is developed by the developing device. When the C image on the exposure drum is developed, the C image is fixed, and then the exposure drum is discharged with the C image held.

In this apparatus, the exposure drum is constructed so that it can be repeatedly used when the charge is removed. After the charge is removed, the exposure drum is uniformly charged again, and then, for example, a static image corresponding to an M image is statically charged. A latent image is formed. This electrostatic latent image is developed and fixed in the same manner as before, and the M image is formed on the C image. After forming the M image, the charge on the exposure drum is removed again, and the Y image and the BK image are formed in the same manner, and a full-color image including BK, C, M, and Y is formed on the exposure drum.

When a full-color image is formed on the photosensitive drum, the full-color image is transferred from the photosensitive drum to a transfer material and then transferred to an image receiving paper to form a color proof.

Regarding such an image forming apparatus, "Printing magazine (published by the Printing Society of Japan), Vol. 73.
No. 8 to Vol. 74 No. 9) DDCP
Forefront (1) and (2) ".

[0020]

By the way, an exposure drum having a photoconductor (photosensitive material) arranged on the outer periphery is applied to an image forming apparatus to which such electrophotographic image formation is applied, and exposure is performed. The DDCP system for producing a color proof by finally transferring an image formed on a drum (photoreceptor) to an image receiving paper has the following problems.

That is, in the conventional apparatus using the exposure drum, any of BK, C, M and Y images is formed on the same exposure drum (photoconductor). Therefore, in order to form an image with a predetermined density and form a high-quality full-color image in which the density of each of BK, C, M, and Y is not too high or low, a color-forming agent (image forming material) such as toner is used. It is necessary to highly adjust the characteristics of for each color. In particular, in an apparatus that performs batch transfer after four-color development of BK, C, M, and Y on the exposure drum (photoreceptor) as described above, the image of the first color is directly placed on the photoreceptor, The second and subsequent images may be formed on the previously formed image or may be formed directly on the photoconductor. Therefore, it is considered that the density control of the formed image is naturally difficult because the developing condition is largely different for each color and for each portion of each color formed image.

Under such conditions, that is, when a multicolor image is formed on the same photosensitive member to form a full-color image, a high-performance color-developing agent such as a toner that does not cause excess or deficiency of density is extremely developed. However, there is a limit to eliminating the density difference for each color by adjusting only the characteristics of the color former and improving the image quality.

In addition, in order to form a good full-color image, it is necessary to perform so-called registration, in which the images of the colors BK, C, M, and Y are superposed without any deviation. For alignment, it is necessary to highly control the formation position of the electrostatic latent image on the exposure drum and to synchronize the exposure drum and the transfer drum at a high level, which complicates the apparatus and increases the cost.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to use an image signal converted into an electrical signal in an electronic publishing system, a desktop publishing system, or an electronic plate making system using a word processor or various computers, especially a digitized image. Color proofs, especially digital color proofs, can be made directly from signals with ease and ease of operation.
An object of the present invention is to provide an image forming apparatus having a simple structure, compact size, and capable of producing a high-quality color proof.

[0025]

In order to achieve the above object, the present invention is directed to a single exposure drum having a photosensitive layer on its outer periphery on which n-color images can be formed as latent images or visible images at predetermined intervals. And is arranged along the outer periphery of this exposure drum,
An exposure device that digitally exposes the photosensitive layer to form an image of one color as a latent image or a visible image on the photosensitive layer; and an n-color developing device that develops the exposed photosensitive layer to the color. The color formed on the exposure drum has a diameter of 1 / n of that of the exposure drum and is wound around a sheet of image-receiving paper to make one rotation by contacting the exposure drum directly or through an intermediate transfer member. And a transfer roller for transferring the image, the n-color image is transferred to the image-receiving paper by continuously rotating the transfer roller n times, and then the image-receiving paper on which the n-color image is formed is discharged. An image forming apparatus characterized by the above is provided.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to the present invention will be described in detail with reference to the preferred embodiments shown in the accompanying drawings. FIG. 1 is a diagrammatic sectional view showing the configuration of an embodiment of the image forming apparatus of the present invention. As shown in the figure, the image forming apparatus 10 of the present invention.
Is an exposure drum having a photosensitive layer, an electrophotographic photosensitive drum having a photoconductor formed on its outer periphery as a photosensitive layer is used, and BK is provided at predetermined intervals on the photosensitive layer on the outer periphery of the drum.
After exposing the four color images of C, M and Y with laser light,
A color proof is produced by sequentially developing a latent image of each color with a wet toner, and transferring the toner images to an image receiving paper one after another and laminating the toner images. Such an image forming apparatus has a single exposure (photoreceptor) having an electrophotographic photosensitive layer 11 on its outer periphery capable of forming four color images of BK, C, M and Y as electrostatic latent images at predetermined intervals. ) The drum 12 and the photosensitive layer 1 disposed in the vicinity along the outer periphery of the exposure drum 12.
1. A charging unit 14 for uniformly charging 1 and a photosensitive layer 11 on the downstream side thereof.
An exposure device 16 for exposing the image according to the digital image data,
The developing device 1 for four colors of BK, C, M and Y is provided on the downstream side.
8, a transfer roller 20 having a diameter ¼ that of the exposure drum 12 on the downstream side thereof, which holds one sheet of image receiving paper C and rotates while contacting the exposure drum 12, and a photosensitive layer on the downstream side thereof. A static eliminator 22 that erases static electricity remaining on 11, a cleaning unit 24 that cleans the photosensitive layer 11 by removing the toner remaining on the photosensitive layer 11 on the downstream side thereof, and a toner transferred to the image receiving paper C. A fixing unit 26 for fixing an image, a feeder unit 28 for supplying the image receiving paper C to the transfer roller 20,
The color proof P on which images of four colors are stacked is discharged from the transfer roller 20 and is stacked thereon.

The exposure drum 12 is an electrophotographic photosensitive drum having a photoconductor as the photosensitive layer 11 on the outer peripheral surface thereof, and is BK (black), C (cyan), M (magenta), and Y (yellow). The four-color image can be formed as an electrostatic latent image on the photosensitive layer 11 around the electrostatic latent image at predetermined intervals, for example, at equal intervals, that is, with the phase shifted by 90 °. Such an image forming apparatus of the present invention has BK, C,
Since each image of M and Y is formed in another area on the photosensitive layer 11, it is possible to form a good image for each color without being adversely affected by other toners (coloring agent, coloring agent), A high quality color proof can be manufactured. Further, if necessary, not only the toner characteristics for each color but also the characteristics of the photoconductor can be adjusted according to each color (toner) of BK, C, M, and Y. Various color proofs can also be produced.

In the illustrated example, 4 of BK, C, M and Y
Although an image for each color is formed on one exposure drum 12 and the exposure drum 12 is used for a four-color plate, the present invention is not limited to this and may be necessary depending on the number of printing original plates to be color-calibrated. It is possible to form a large number of color plate images, that is, n color images on one exposure drum 12 and arrange them at predetermined intervals to use for n color plate. Here, n may be a natural number, but it is preferable that n is two or more colors. The intervals of the n-color images are not particularly limited as long as they are predetermined intervals, but it is preferable to arrange them at equal intervals every 1 / n of the entire outer peripheral length of the exposure drum 12.

As the photosensitive layer 11, the light of the electrophotographic photosensitive member is used.
What kind of material can be used as long as it forms a conductor?
May be, for example, metal such as aluminum (conductive)
Vacuum-deposited selenium (amorphous Se) and selenium on the surface of the support
And Te and As as impurities ₂ S₃ Complex type S including etc.
a photoconductive layer made of e, or aluminum, made conductive
Provided on a flexible conductive support such as plastic or paper.
Zinc oxide (ZnO), cadmium sulfide (CdS), etc.
Photoconductive material prepared by dispersing other photoconductive materials in a binder such as resin
Photoconductive layer containing substances (photosensitive resin-dispersed electrophotographic photoreceptor
Layer), titanium oxide, inorganic light such as amorphous silicon
Photoconductive layer containing conductive material, and phthalocyanine compound
A photoconductive layer containing an organic photoconductive material such as is used. This
The exposure drum 12 having these photosensitive layers 11 is made of aluminum.
Outside of a drum made of metal support itself such as um
The photoconductive layer may be formed directly on the surface,
Outside of a thin cylinder made of flexible conductive support in advance
Cylindrical electrophotographic image with the above photoconductive layer formed on the surface
The optical body may be externally fitted to a metal drum, or a sheet
-Shaped electrophotographic photoconductor in a cylindrical shape on a metal drum
It may be attached. The surface side of the photosensitive layer 11 should be protected.
It may have a protective layer.

The charging section 14 is the photosensitive layer 1 of the exposure drum 12.
1 for uniformly charging the photosensitive layer 11 with a corona charger or the like, but any material capable of uniformly charging the photosensitive layer 11 may be used.

As shown in FIG. 2, the exposure device 16 is arranged near the outer periphery of the exposure drum 12 on the downstream side of the charging section 14,
By exposing a uniformly charged photosensitive layer 11 moving at a predetermined sub-scanning speed on the exposure drum 12 rotating at a predetermined speed to a laser beam, a digital halftone image of a certain color is exposed. A laser light source 32 that emits a laser beam L, which is written as an electrostatic latent image, and an optical modulator 34 such as an AOM (acousto-optical modulator) that intensity-modulates the laser beam L according to an original document image, Intensity-modulated laser light L
On the exposure drum 16 and the optical deflector 36 such as a rotary polygon mirror for reflecting and deflecting the light and performing main scanning on the exposure position 16a in a direction substantially orthogonal to the rotation direction (the moving direction of the photosensitive layer 11). Scanning lens 38 which is composed of an fθ lens or the like for focusing a uniform beam diameter at any main scanning position on the photosensitive layer 11, a modulation circuit 40 which drives the light modulator 34, and digitally processes a master copy original image. And a digital halftone image signal, which is then D / A converted and supplied as an analog image signal.

Here, the laser light source 32 is a laser such as a semiconductor laser (LD), a He-Ne laser, a gas laser such as an Ar laser, a CO ₂ laser, or the like, which has an emission wavelength at which the spectral sensitivity of the photosensitive layer becomes a predetermined value or more. Any laser can be used, and a light emitting diode (LED) can be used as long as it has sufficient light intensity. Also, L
When D or LED is used, LD or LED may be directly modulated without using the optical modulator 34. In addition to the laser light source 32, a normal light source such as a sodium lamp, a xenon lamp, or a mercury lamp may be used as the light source. Instead of the optical modulator 34, a known optical shutter using various linear and non-linear electro-optical materials such as a liquid crystal shutter and an electro-optical effect shutter using PLZT may be used. When the optical deflector 36 is not used, the above-mentioned optical shutters may be arranged in an array on the main scanning line defined at the exposure position 16a and the optical shutter array may be turned on / off (opened / closed) imagewise. Good. Further, exposure may be performed by arranging LDs and LEDs in an array instead of the optical shutter array and turning the LD array and LED array on and off in an imagewise manner.

The light deflector 36 is not limited to a polygon mirror, that is, a rotary polygonal mirror, and may be any one capable of deflecting the laser light L in a one-dimensional direction by a predetermined angle, and a galvanometer mirror, a resonant scanner or the like may be used. Is.

The image information signal which is image-processed by the image processing device 42 is a color negative film obtained by color separation from an original drawing, a photograph or a plate, a black negative film obtained from characters or a chart, or each of these colors. Even if the lith film of each color plate obtained from the plate negative film or the image signal of each color of each color plate read from the block copy document, electronic printing by a word processor or computer, DTP (desktop publishing ( It may be a digitized image signal of each color synthesized or produced by, for example, desktop publishing), or an image data signal obtained in an electronic plate making system, in particular, a digital image data signal subjected to digital processing after reading.

The developing section 18 is arranged in the vicinity of the outer periphery of the exposure drum 12 and on the downstream side of the exposure device 16, and transfers one or a color plate electrostatic latent image formed on the exposed photosensitive layer to the toner of that color. 1 for wet toner development, and in the example shown in FIG. 1, wet toner developing devices 18BK, 18C, 18M and 18 using four color liquid toners of BK, C, M and Y.
The liquid toner of four colors is used, and the liquid toner corresponding to the color is sprayed onto the image of the color plate (electrostatic latent image) only when the image of the color plate of the color comes, and toner development is sequentially performed. To do.

A wet toner developing device 18Y for developing a Y image will be described as a representative example of the wet toner developing device. As shown in FIG. 3, the tank 44 for containing the liquid toner developer F and the liquid toner developer F are used. A jet nozzle 46,
Two developing electrodes 48, 48 forming the ejection nozzle 46
, Liquid toner developer ejecting means 50 for ejecting liquid toner developer F from ejection nozzle 46, and squeeze roller 52.
Composed of and. In the wet toner developing device 18Y, the charged toner particle developing electrode 48 in the liquid toner developer F ejected from the ejection nozzle 46 by the ejection means 50,
Toner development is performed by adhering a predetermined amount to the image portion where the electrostatic latent image is formed according to the electric field strength between the photosensitive drum 11 and the photosensitive layer 11 of the photosensitive drum. Here, the excess liquid toner developer is squeezed from the toner image on the photosensitive layer 11 of the exposure drum 12 developed by the liquid toner developer F by the squeeze roller 52 that rotates in close contact with the photosensitive layer 11.

When the toner development for one color (color plate) is completed, the exposure drum 12 further rotates in the direction of the arrow, and the toner image electrostatically adhered to the photosensitive layer 11 by the Coulomb force is transferred to the downstream side thereof. It is dried by evaporating the excess insulating liquid by the arranged drum drying means 19. The drying means 19 supplies hot air or hot air for drying and does not necessarily have to be provided, but the squeeze roller 52 is used.
It is preferably provided when sufficient liquid removal cannot be achieved by the substrate.

In this way, the photosensitive layer 11 of the exposure drum 12 is exposed by the exposure device 16, and the developing portion 18, for example, 1
It is developed and dried by 8BK, and one color, for example, BK
When the (black) toner image is formed, a toner image of one color, for example, C (cyan) is formed next. By repeating the exposure and development by the exposure unit 16 and the development unit 18 as described above, toner images for four colors of BK, C, M, and Y are accurately formed at equal intervals in the circumferential direction of one exposure drum 12. You can go. In the case of n-color printing, the photosensitive layer 1 is similarly formed.
2 it is necessary to accurately form toner images for n colors in the circumferential direction of the exposure drum 12 at equal intervals. Therefore, the wet toner developing device requires n colors, and the exposure drum 12 requires n color plates. Need to

The liquid toner developer used in the present invention is not particularly limited, and any of those used in conventional wet development can be used. That is, the liquid toner in the normal wet development generally forms a fine image of organic, inorganic pigments, dyes, etc. classified into the particle size range required for the liquid medium using a petroleum odorless solvent as a general constitution. Particles and charge control agents, dispersion stabilizers and other additives are added. When an electrophotographic photoreceptor having an electrostatic latent image is dipped in this, a Coulomb force acts between the electrostatic charge forming the latent image and the charged particles in the liquid toner developer, and the charged particles are electrodeposited on the latent image. And developed.

As such a liquid developer, for example,
A dispersion of colored or uncolored polymer or copolymer particles in an insulating solvent such as a paraffinic solvent (for example, Isopar G or Isopar H) is used. When coloring, a pigment such as carbon black is used as the polymer. Those coated with or copolymer are used. Further, the liquid toner developer may contain various additives used in the art, such as a dispersant.

The transfer roller 20 is arranged on the downstream side of the developing unit 18 along the outer periphery of the exposure drum 12, around the outer periphery of which an image receiving paper is wrapped and held by a known holding means such as a paper gripper, and the like. The toner image carried on the photosensitive layer 11 of the exposure drum 12 is transferred to the image receiving paper held on the outer periphery thereof by contacting the toner 12 with a predetermined pressure.

Here, when the toner image on the exposure layer 11 of the exposure drum 12 has four color plate images of BK, C, M, and Y, the exposure drum 12 makes one rotation. The transfer roller 20 makes four full-color images on the held image-receiving paper by rotating four times while holding one image-receiving paper on the outer periphery thereof, thereby producing a full-color proof P. After that, the transfer roller 20 separates the color proof P on which the color image formation is completed, discharges it to the delivery unit 30, and holds the new image receiving paper sent from the feeder unit 28. Therefore, the diameter of the transfer roller 20 is ¼ of the diameter of the exposure drum 12, and the transfer roller 20 rotates forward at the same peripheral speed as the peripheral speed of the exposure drum 12. Of course, if the exposure drum 12 is for n-color plate, the diameter of the transfer roller 20 is 1 / n of the diameter of the exposure drum 12, and the transfer roller 20 rotates n times while the exposure drum 12 makes one rotation. Therefore, in the image forming apparatus of the present invention, it is not necessary to perform alignment (registration) between the exposure drum and the transfer roller as in the conventional apparatus, and it is possible to secure good workability with a simple configuration. ..

The static eliminator 22 is arranged on the downstream side of the transfer roller 20 along the outer periphery of the exposure drum 12, and the electric charge remaining on the photoconductor forming the photosensitive layer 11 of the exposure drum 12 after the toner image is transferred. A known static eliminator can be used to remove the.

Further, the cleaning means 24 is arranged on the downstream side of the static eliminator 22, and the photosensitive layer 1 of the exposure drum 12 after the transfer is transferred.
To remove the toner remaining on 1 and clean it,
A flexible substrate (cloth not shown) impregnated with a cleaning liquid such as an insulating carrier liquid used for the liquid toner developer F is pressed against the surface of the photosensitive layer 11 of the exposure drum 12 to leave the toner on the surface. It is cleaned by wiping off stains and dirt, and dried by a drying means (not shown). The cleaning unit 24 is not necessarily provided when the toner image is completely transferred from the photosensitive layer 11 of the exposure drum 12 onto the image receiving paper C, but is always clean before being uniformly charged by the charger 14. It is preferable to provide the outer surface.

The fixing unit 26 is arranged in the conveyance path of the image receiving paper C (color proof P) between the transfer roller 20 and the delivery unit 30, and from the photosensitive layer 11 of the exposure drum 12 as the transfer roller 20 rotates. This is for fixing the toner image transferred to the image receiving paper adhered to the outer periphery of the transfer roller 20, and is composed of a heater such as a lamp heater or a panel heater for heating and fixing the toner image on the image receiving paper.

The feeder unit 28 automatically feeds the stacked sheet-shaped image receiving sheets one by one to transfer the transfer rollers 2 to each other.
Although not shown, a friction type or a suction type that uses a suction cup to move only the topmost paper by pressing the ridges or wheels against the topmost image receiving paper, and air or vibration as necessary It is possible to use a conventionally known automatic sheet feeding device for sheets, which uses, for example, sorting by the above, and further uses a roller conveying system, a belt conveying system, and the like. The delivery unit 30 receives the color proof in the color image format from the transfer roller 20 and discharges or stacks the color proof at a predetermined position, and an automatic or semi-automatic paper discharge device can be applied. For example, a conventionally known paper discharge device such as a roller transport system, a belt transport system chain delivery, or pile delivery can be used. When the number of color proofs P is small at a time, the delivery unit 30 may be composed of a tray, a stacker, etc. provided at the rear of the transport system.

In the illustrated example, the toner development by the developing unit 18 is wet toner development, but by selecting the photosensitive layer 11 of the electrophotographic photosensitive member which becomes the exposure drum 12,
Dry development may be performed by using the developing unit 18 as a dry toner developing device. In this case, it is not necessary to provide the drying means 19. The dry toner for dry development and the dry toner developing device are not particularly limited, and conventionally known dry toner and dry toner developing device can be used.

The electrophotographic image forming apparatus for producing the color proof shown in FIG. 4 is basically constructed as described above, but the image forming apparatus of the present invention is not limited to this. The image forming apparatus shown in FIGS. 4 to 6 is also included in the scope of the present invention depending on the photosensitive material having a photosensitive layer used for image formation.

The image forming apparatus 60 shown in FIG. 4 uses a roll-shaped photosensitive material 64 as a photosensitive material having a photosensitive layer, and has a photosensitive material supply device 62 in the exposure drum 12 and the photosensitive material 64. After being attached and fixed to the entire outer periphery of the exposure drum 12, the image of each color plate is exposed by the exposure device 16 at predetermined intervals for each color, and only the image portion of each color of the exposed photosensitive material 64 is exposed. After being developed by the developing device 18, the color proof P is manufactured by transferring the image onto a sheet of image-receiving paper wound around the outer periphery of the transfer roller 20 so that each color is superimposed.

The photosensitive material supply device 62 is used for the exposure drum 12.
The used photosensitive material 64b is wound around the entire circumference of the exposure drum 12, and at the same time, the unused photosensitive material 64a is unwound around the entire circumference of the exposure drum 12,
To the outer circumference of the exposure drum 12, and has a fixing means (not shown) for fixing the winding rollers 68, 68 for winding the used photosensitive material 64b.

In the image forming apparatus 60 of the illustrated example, the developing devices 18BK ', 18C', 19M for the respective colors of the developing section 18 are used.
A developing device suitable for the photosensitive material 64 used may be used for ′ ′ and 19Y ′. For example, when the photosensitive material itself has a color-developing property, images of all colors are
You may make it develop with one developing device.

The exposure device 16 may also be selected as the most suitable one according to the photosensitive material 64 used. Further, the fixing unit 26 may not be provided depending on the photosensitive material 64 used.

As described above, in the present invention, the exposure drum having a photosensitive layer is not limited to the electrophotographic photosensitive drum shown in FIG. 1, but the roll-shaped photosensitive material shown in FIG. 4 or a sheet not shown. It is possible to use a metal drum or the like in which a photosensitive material having a shape of a circle is fixed to the outer periphery thereof by a known method. As such a photosensitive material, a photosensitive material such as an electrophotographic photosensitive material, a photosensitive resin material (photopolymer), a photosensitive pressure-sensitive resin material, a photosensitive heat-sensitive resin material, or a silver salt photosensitive material can be used.

Further, such a light-sensitive material may have a color-developing property for each color, or a specific dye, for example, in the case of four colors, BK, C, M and Y dyes are mixed. , By exposing, and further developing if necessary,
It may be a photosensitive material that can be transferred to an image receiving paper. Further, even when the light-sensitive material itself has a color-forming property, the light-sensitive material itself may be a material of the same quality and may develop a color for each color by exposure and / or development. At the position to be exposed and formed, the color forming property of the light-sensitive material is set to one frame (1
It may be a photosensitive material in which coma is made continuous so as to be different for each portion (on which an image of one color plate is formed). Therefore, since it is possible to use one frame of photosensitive material that develops only that color for each of the BK, C, M, and Y images, it is possible to use a single photosensitive material to form a color image as compared with a conventional apparatus. It is relatively easy to obtain excellent color development and produce a high-quality color proof.

In the above-mentioned example, the color images of the respective colors formed on the exposure drum are directly transferred to the image receiving paper.
The present invention is not limited to this, and the image forming apparatus 7 shown in FIG.
0, the intermediate transfer drum 72 may be interposed between the exposure drum 12 and the transfer roller 20.

The image forming apparatus according to the present invention has been described above with reference to the preferred embodiments, but the present invention is not limited to this. For example, depending on the photosensitive layer of the exposure drum,
It is not always necessary to have both the exposure device and the developing section, and it may consist of only the exposure device, may have a large number of exposure devices, and may not have heat rays such as laser beams. For example, one that forms an image on a heat-sensitive material by using it, one that transfers the image formed on the surface layer of the exposure drum by an inkjet method to image-receiving paper, or one that obtains a copied image or a reproduced image other than color proof. It goes without saying that various improvements and design changes can be made without departing from the scope of the invention.

[0057]

As described in detail above, according to the present invention,
Images of n colors are accurately written in the photosensitive layer formed or held on the outer periphery of one exposure drum at equal intervals in the circumferential direction, and then developed, and images of each color are sequentially held by the transfer roller. By repeating the transfer to the image receiving paper, a color image of n colors is formed. Therefore, even in full color, it is not necessary to align (register) the images of each color. Further, since the image forming apparatus of the present invention forms n-color images at different positions on the photoconductor (photosensitive material), each image is not adversely affected by another image. Furthermore, not only the characteristics of each color material but also the characteristics of the photoconductor can be adjusted for each color image (color material),
A high quality color proof can be manufactured.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an example of an image forming apparatus according to the present invention.

FIG. 2 is a schematic sectional view of an example of an exposure device section of the image forming apparatus according to the present invention.

FIG. 3 is a schematic sectional view of an example of the developing device of the image forming apparatus according to the present invention.

FIG. 4 is a schematic sectional view of another embodiment of the image forming apparatus according to the present invention.

FIG. 5 is a schematic sectional view of another embodiment of the image forming apparatus according to the present invention.

[Explanation of symbols]

 10, 60, 70, image forming apparatus 11 photosensitive layer 12 exposure drum 14 charging section 16 exposure apparatus 18 developing section 20 transfer roller 22 charge eliminating section 24 cleaning means 26 fixing section 28 feeding section 30 delivery section

Claims (1)

[Claims] 1. An exposure drum having, on its outer periphery, a photosensitive layer capable of forming an n-color image as a latent image or a visible image at predetermined intervals, and is arranged along the outer periphery of the exposure drum.
An exposure device for image-exposing the photosensitive layer to form an image for one color as a latent image or a visible image on the photosensitive layer; an n-color developing device for developing the exposed photosensitive layer to the color; Having a diameter of 1 / n of the exposure drum, one sheet of image-receiving paper is wound around and rotated once by contacting the exposure drum directly or via an intermediate transfer member, and the one of the color formed on the exposure drum is rotated. A transfer roller for transferring an image, wherein the transfer roller is continuously rotated n times to transfer an image of n color onto the image receiving paper, and then the image receiving paper on which the image of n color is formed is discharged. An image forming apparatus characterized by.