JPH02262667A - Electrophotographic plate making device - Google Patents

Abstract

PURPOSE:To provide the device which is compact over the entire part and is low in cost by using a conductive material to constitute a transporting roller on the base side of a photosensitive body of the paired transporting rollers provided apart a prescribed spacing from each other on the upstream side for the transportation of a corona electrifier disposed only on the photosensitive layer side of the photosensitive body. CONSTITUTION:The conductive material is used to constitute a transporting roller 30a on the base side of the photosensitive body of the faired transporting rollers 30a, 30b which are provided apart the prescribed spacing on the upstream side for transportation of the corona electrifier 32 disposed only on the photosensitive layer side of the photosensitive body and are used for crimping and transporting the photosensitive body. The decrease in the electrostatic charge quantity is, therefore, obviated even without the corona electrifier for the rear surface and members for grounding, such as metallic rolls and destaticizing brushes. The electrifying part and eventually the device are formed compact over the entire part and the cost thereof is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a wet electrophotographic engraving device, and more particularly, it performs charging, laser exposure, wet toner development and The present invention relates to an electrophotographic engraving device that continuously performs fixing.

<Prior Art> Conventionally, a camera-type electrophotographic device has been used for directly photoengraving a printing original plate from a draft manuscript. FIG. 4 shows a cross-sectional structural view of an example of such an electrophotographic engraving apparatus, for example, the apparatus disclosed in Japanese Patent Application No. 89373/1989 filed by the present applicant.

As shown in the figure, in an electrophotographic engraving apparatus 100, an electrophotographic photoreceptor P is pulled out from a photoreceptor supply section 102 by a pull-out roller 104, and a corona i of a double corona system is used.
After being uniformly charged by a T-type device 108 and conveyed by a conveying means, and cut into a predetermined length by a cutter 106, the photographing unit 11
It is held at a predetermined position of 0 by suction means or the like.

On the other hand, the draft manuscript S is placed on the manuscript table with its manuscript side facing up.
2 is placed at a predetermined position.

Here, when a light source (not shown) emits light for a predetermined period of time, the photographing light irradiated from the light source onto the original manuscript S is reflected by the surface of the original manuscript S, is reflected by the upper mirror 114, and is reflected by the lens 1.
16. This focused photographing light is supplied from the photoreceptor supply section 102 by a conveying means, and is imaged on the electrophotographic photoreceptor P held in the photographing section 110, forming an electrostatic latent image. The photographed photoconductor P is conveyed by a conveyance means to a developing section 118, where its electrostatic latent image is developed with toner and fixed at a fixing section 120, and its non-image area is subjected to a hydrophilic treatment at an etching section 122. Thereafter, the photoreceptor P is dried and discharged from the outlet 124 as a printing original plate.

On the other hand, a document image is scanned and exposed to a uniformly charged sheet-like electrophotographic photoreceptor using laser light to form an electrostatic latent image, and then the electrophotographic photoreceptor on which the electrostatic latent image has been formed is exposed. A laser plate making device that develops and fixes toner was published in Japanese Patent Application Laid-Open No. 1986-12.
No. 5371 and No. 82-125372. The plate-making apparatus disclosed herein is an apparatus that continuously performs charging using a double corona method, laser exposure, toner development, and fixing while transporting an electrophotographic photoreceptor using a transport means. The electrophotographic photoreceptor is smoothly transported by the transport roller constituting the means, and the photoreceptor is smoothly transported within the toner developing section. The fixed electrophotographic photoreceptor obtained by these apparatuses is subjected to hydrophilic treatment by etching and used as a printing original plate.

By the way, the electrophotographic printing apparatus disclosed in Japanese Patent Application No. 63-89373 can obtain a printing original plate having a homogeneous image without unevenness in developed density, but since it performs one-shot exposure, at least plate making is possible. This requires a photographing stand the size of the largest original printing plate, which results in a large-sized device configuration, and a master iF4 is always required.

By the way, recently, for example, image information input from various media such as computers, graphics, videos, high-definition televisions, CAD/CAM cameras, image information created by plotting machines, etc., images read from manuscripts by scanners, etc. Information, digital image information converted into electrical signals such as character information manually generated from a computer phototypesetting machine or word processor, and digital image information already stored as a database on an optical disk, CDFLOM, magnetic disk, magnetic tape, etc. Attempts have been made to create a complete original for printing either by itself or by processing it with various image processing devices such as computers.
Further, attempts have been made to directly make a plate from this digital image information, but the above-mentioned plate making apparatus cannot cope with this attempt.

On the other hand, JP-A-62-125371 and JP-A-62-12
The electrophotographic engraving apparatus disclosed in No. 5372 laser-exposes a digital image signal read from a completed manuscript or a digital image signal processed by an image processing device such as a computer and completed as a manuscript onto an electrophotographic photoreceptor for plate making. Charging, laser exposure, toner development, and fixing can be performed continuously, and during these steps, the photoreceptor is conveyed smoothly, but laser exposure allows for higher image quality. No consideration is given to the problems that arise when obtaining a toner image.

In order to obtain high-quality images, it is necessary to increase the scanning line density during laser exposure using the raster scan method. For example, in a normal laser beam printer, 40
It can be said that the image quality is quite high at around 0 dPi, but the original printing plate (
(hereinafter referred to as a printing plate), it cannot be said that the image quality is high unless it is 1000 dPi or higher.

Therefore, in order to obtain a high-quality image by laser exposure, the sub-scanning speed, that is, the conveyance speed of the photoreceptor must be slow.
For example, the scanning speed in the above-mentioned high-quality laser exposure electrophotographic device depends on the scanning line density, but it is 1/2 of the photoreceptor conveyance speed in the one-shot exposure electrophotographic device.
The transport speed is as low as 1/25 to 1/4.

<Problem to be solved by the invention> By the way, the fourth patent disclosed in Japanese Patent Application No. 89373/1983
Even in the electrophotographic engraving device shown in the figure,
Also in the laser plate making apparatus disclosed in No. 2-125371 and No. 62-125372, in the charging section that applies electric charge to the sheet-like electrophotographic photoreceptor that becomes the printing original plate,
Since this is a double corona method in which corona chargers are placed on both sides of the photoconductor and corona charging is performed from both the front and back sides of the photoconductor, the structure of the charging section is complicated, and the charging section and the entire device become more compact and costly. This was a factor that prevented him from going down.

In addition, in a single corona method in which a corona charger is disposed only on the surface of the sheet-like electrophotographic photoreceptor, that is, only on the photosensitive layer side, and corona charging is performed only from the photosensitive layer side, a predetermined amount of charge is applied to the photosensitive layer. Since it is difficult to ground the photoreceptor, a conductive member such as a metal roll or a static elimination brush is placed on the back surface of the photoreceptor, that is, on the support side, facing the corona charger on the front surface, and brought into contact with the back surface of the photoreceptor. I had to take it.

For this reason, these have been a factor in increasing the cost of the charging section and, by extension, the entire device, and being a factor in preventing the device from becoming more compact.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a simple structure for making a printing original plate by continuously carrying out charging, laser exposure, toner development, and fixing while transporting an electrophotographic photoreceptor at a low speed. An electrophotographic engraving apparatus is provided, in which the charging section allows sufficient uniform charging even when corona charging is performed only from the photosensitive layer side of the photoreceptor, and the charging section and the entire apparatus can be made more compact and cost-reduced. It is on offer.

<Means for Solving the Problems> In order to achieve the above object, the present invention uniformly charges an electrophotographic photoreceptor having a photosensitive layer containing a photoconductive substance and a support supporting this photosensitive layer. a charging section for exposing the photoconductor, an exposure section for exposing the photoconductor, a developing section for developing toner on the exposed photoconductor, and a fixing section for fixing the developed photoconductor, and conveying the photoconductor. Charging, exposure, development,
In an electrophotographic engraving apparatus that continuously performs fixing and makes printing original plates, a corona charger provided in the charging section is disposed only on the photosensitive layer side of the photoreceptor, and the corona charger is disposed on the conveying upstream side of the corona charger. Provided is an electrophotographic engraving apparatus, characterized in that a pair of conveyance rollers which are provided at a predetermined distance from each other and are used to sandwich and convey the photoreceptor, the conveyance roller on the support side of the photoreceptor is made of a conductive material. It is something to do.

Preferably, the conductive material is metal.

Further, it is preferable that the distance between the corona charger and the clamping point of the pair of transport rollers is 50 mm or less.

Further, the sub-scanning conveyance speed of the photoreceptor is 100 am/
It is preferably less than sec, more preferably 25
mm/sec is good.

Further, the surface resistivity of the back surface of the support of the photoreceptor is 5×1
It is preferable that the resistance is 0.09 Ω or less.

<Function of the Invention> The electrophotographic engraving apparatus of the present invention provides the electrophotographic photoreceptor, when the electrophotographic photoreceptor is transported, for example, when the electrophotographic photoreceptor is scanned and transported at a sub-scan transport speed of 25 mm/sec or less for laser exposure. A corona charger as a charging unit for uniformly charging the body is provided only on the photosensitive layer side of the photoreceptor, and a corona charger is provided upstream of the corona charger at a predetermined interval D, for example, 50 mm or less. By using a roller made of a conductive material, for example, a metal roller, as the conveyance roller on the support side of the photoreceptor among the set of clamping conveyance rollers, it is possible to eliminate the conventional method of disposing the conveyance roller facing the corona charger with the photoreceptor sandwiched therebetween. Even if the corona charger for the back side and the grounding members such as metal rolls and static elimination brushes are eliminated, the amount of charging does not decrease, and therefore the configuration of the charging section and the entire device can be made more compact and the cost can be reduced. The surface resistivity of the support side surface of the photoreceptor used here is 5X10'
Ω or less, and if the resistance is low, the predetermined interval can be made larger than 50 mm in order to obtain the same amount of charge. However, in order to obtain a desired amount of charge, the narrower the interval, the better, and the slower the conveyance speed, the better.

<Embodiments> Hereinafter, an electrophotographic engraving apparatus according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1 is a schematic cross-sectional view showing an embodiment of the electrophotographic engraving apparatus of the present invention.

As shown in the figure, the electrophotographic engraving apparatus 10 includes a photoreceptor supply section 12 that supplies an electrophotographic photoreceptor P, an f-electrification section 14 that uniformly charges the photosensitive layer of the photoreceptor P, and a --like charged photoreceptor. An exposure section 16 irradiates the photoconductor P with laser light to form an electrostatic latent image on the photoconductor P, and an exposure section 16 that forms an electrostatic latent image on the photoconductor P, and develops the electrostatic latent image formed on the photosensitive layer of the photoconductor P with wet toner to form a toner. It has a developing section 18 that forms an image, and a fixing section 20 that fixes the toner image formed on the photosensitive layer of the developed photoreceptor P.

The electrophotographic photoreceptor P used in the present invention is made of zinc oxide (ZnO) or cadmium sulfide (C), as shown in FIG.
A photosensitive layer P1 containing a photoconductive substance such as dS) is dispersed in a binder such as a resin, and a so-called resin-dispersed electron structure in which this photosensitive layer P1 is provided on a support P2 having at least a conductive surface. Any photographic photoreceptor can be used.

The support P2 may be any flexible conductive material; for example, it may be a conductive material support made of metal such as aluminum, or the surface of a plastic film, paper, etc. may be made of carbon, metal, etc. It is also possible to use materials treated with electrically conductive substances such as the above and composites of the above-mentioned materials. For example, a paper support treated with conductivity, a paper support treated with conductive waterproofing, a paper support coated or laminated with a conductive polymer on one or both sides, a conductive polymer support, etc. are suitable. The conductive polymer referred to herein may be a polymer itself that is conductive, or a polymer containing the above-mentioned conductive substance.In the present invention, the support P2 of the photoreceptor P used is
The surface resistivity of fllJ (back surface) is preferably 5×10 9 Ω or less.

Further, the support P2 may be either a belt-like material or a sheet-like material, but it is more preferably one that can be wound into a roll shape and cut into a sheet shape.

As the photosensitive layer P1, in addition to the above-mentioned zinc oxide and cadmium sulfide, a photoconductive layer containing an inorganic photoconductive substance such as titanium oxide and amorphous silicon, and a photoconductive layer containing an organic photoconductive substance such as a phthalocyanine compound are used. Furthermore, if necessary, an intermediate layer may be provided between the conductive support and the photoconductive layer, or a backing layer may be provided on the side of the support opposite to the photoconductive layer.

Here, the non-image areas of the photosensitive layer P1 are rendered hydrophilic by a hydrophilic treatment liquid (for example, an aqueous solution containing a ferrocyanide compound) after the toner image is fixed.

A typical example of such an electrophotographic photoreceptor is the electrophotographic master ELP mark, which is a zinc oxide-resin dispersion type.
and Electrophotographic Master ELP Mark II.

A magazine 22 that accommodates therein an electrophotographic photoreceptor P wound into a roll with the photoreceptor layer P1 inside is detachably attached to the photoreceptor supply unit 12, and an ejection port for the photoreceptor P of the magazine 22 is attached to the photoreceptor supply unit 12. Pull-out rollers 24a and 24b are provided corresponding to the slit-like opening in 22a. One pull-out roller 24a is connected to the other pull-out roller 24 indicated by a dotted line.
It is configured to be movable between a position away from b and a contact position shown by a solid line. Here, the pull-out roller 24a is in a separated position shown by the dotted line until the magazine 22 is installed, and the tip of the photoreceptor P protruding from the outlet of the magazine 22 is inserted between the take-out rollers 24a and 24b, and the magazine When the photoreceptor 22 is installed in a predetermined position, it moves to the position shown by the solid line and securely clamps the tip of the photoreceptor P between it and the pull-out roller 24b. At this time, it is preferable that the pull-out roller 24a is urged toward the pull-out roller 24b by an unillustrated urging means.

A cutter 26 is provided adjacent to the front of the pull-out rollers 24a and 24b (here, the downstream side of the conveyance of the photoreceptor P).

In front of the cutter 26, a descending conveyance guide 28 is provided, and further in front of the conveyance guide 28, conveyance rollers 30a and 30b are provided at a predetermined distance from the cutter 26. In the present invention, the conveyance roller 30a that comes into contact with the back surface (support P2 side) of the photoreceptor P is made of a conductive material. Any conductive material may be used as long as it has a surface resistivity of 10'Ω or less, and for example, metal is preferable. As the metal, there is no particular restriction, but aluminum and the like are preferable. On the other hand, conveyance roller 3
Since Ob comes into contact with the photosensitive layer P1 of the photoreceptor P, it is preferable to have appropriate softness, and for example, it is preferable that at least the surface is made of carbon-containing acrylbutylene butadiene rubber (NBR).

The conveyance rollers 30a and 30b are rotationally driven by a drive source such as a motor (not shown) via a clutch. Here, the pull-out roller 24a.

24b, the photoreceptor P is pulled out from the magazine 22 with its photoreceptor layer P1 facing downward, and its leading end touches the conveyance roller 30.
a, 30b, the transport rollers 30a, 30b
The clutch is disengaged and its rotation is stopped, but the pull-out rollers 24a and 24b continue to rotate and pull out the photoreceptor P, so that the photoreceptor P is stored in a loop shape on the conveyance guide 28. After that, when a predetermined length of photoreceptor P is pulled out, the pull-out rollers 24a and 24b stop, and the cutter 26
cuts the photoreceptor P into a sheet.

In front of the conveyance rollers 30a and 30b, a corona charger 32 constituting the charging section 14 is disposed at a predetermined distance in front of the photoreceptor P only on the surface side (1!f!', light layer P1 side), and is separated by a predetermined distance. The sheet-like electrophotographic photoreceptor P conveyed by rollers 30a and 30b is uniformly charged.

Normally, the corona charger 32 applies an electric charge only to the surface of the photoreceptor P on the photosensitive layer P1 side, but at this time, an electric charge of the opposite sign is not supplied to the back surface of the photoreceptor P (the surface on the support P2 side). Otherwise, the photoreceptor FIPI cannot be charged properly. Therefore, in the present invention, the conductivity of the support P2 of the photoreceptor P is used to support the photoreceptor P at a position facing the corona charger 32 and at a position away from the corona charger 32. The surface on the body P2 side is a metal conveyance roller 30a.
It is grounded by this. Corona charger and conveyance roller 3
Clamping points 0a and 30b (to be precise, metal conveyance roller 3
The distance between 0a and the contact point with the back surface of photoreceptor P is 50 m.
This distance I! is preferably less than m! Although D is preferably narrower, the surface resistivity of the back surface of the electrophotographic photoreceptor P is 107
Although it is a high resistance material of ~10 ohms, when the surface resistivity of the photoreceptor P used in the present invention is set to 5×io''Ω or less, and the sub-scanning conveyance speed of the photoreceptor P is set to 25 rats/sec or less. Even if the distance is 50 mm, it is possible to sufficiently charge a predetermined amount of charge.

The exposure section 16 includes a large-diameter writing drum 34 that wraps around the surface of the photoreceptor P charged in a negative manner and conveys it in the sub-scanning direction;
A sub-scanning conveyance means that limits the exposure position 34a and brings the photoreceptor P into contact with the writing drum 34 without loosening. A photoreceptor detection sensor 40 and a laser light source 42 that emit laser light, a light modulator 44 such as an AOM (acousto-optic modulator) that modulates the intensity of the laser light according to the original image, and an intensity modulator 44 that modulates the intensity of the laser light according to the original image. an optical deflector 46, such as a rotating polygon mirror, which reflects and deflects the generated laser light to perform main scanning on the exposure position 34a of the writing drum 34 in a direction substantially perpendicular to the direction of rotation thereof (the conveyance direction of the photoreceptor P); A scanning lens 48 consisting of an fθ lens or the like that focuses the laser beam to a uniform beam diameter at any main scanning position on the writing drum 34, and a modulation circuit 50 that drives the optical modulator 44.
and an image processing device 52 that supplies the original image as an analog image signal.

Here, the nip rollers 36 and 38 are located at a predetermined distance from the writing drum 34 shown by the dotted line until the photoconductor P is conveyed, and the photoconductor detection sensor 40 detects the leading end of the photoconductor P. After a predetermined period of time has elapsed (for example, when the tip of the photoconductor P is inserted between the nip roller 36, 38 and the writing drum 34), the photoconductor P moves to the position shown by the solid line and the photoconductor P is inserted between the writing drum 34 and the nip roller 36, 38. The photoreceptor P is brought into contact with the writing drum 34 without any gaps. Further, the nip rollers 36 and 38 are applied to the writing drum 3 with a predetermined pressing force by a biasing means (not shown).
It is preferable to bias it toward the 4th side.

The writing drum 34 transports the photoreceptor P at a constant speed in the sub-scanning direction substantially perpendicular to the main scanning direction to write the original image in the main scanning direction using the laser beam, and transfers the photoreceptor P to the photosensitive layer P1 of the photoreceptor P using the laser beam. Since it performs two-dimensional writing, it is preferably driven by a DC motor with high rotational accuracy.

Due to the rotational drive of the writing drum 34, the sub-scanning conveyance speed of the photoreceptor P needs to be slow in order to obtain high image quality. For example, it is preferable that the scanning line is 1000 dPi or more, and in this case, the sub-scanning conveyance speed, that is, the conveyance speed of the photoreceptor P is the charging section 14, the exposing section 16, the developing section 18,
The fixing unit 20 is preferably 100 am/sec or less, preferably 25 am/sec, more preferably 10 m/sec or less. There is no need to set a lower limit, but it is too slow. Since plate making takes too much time, the speed may be set to about 2.5 am/sec.

The photoconductor detection sensor 40 may be of any type as long as it can detect the arrival of the photoconductor P. For example, it is composed of a light-emitting light-receiving element, and the tip of the photoconductor P passes between them and detects by blocking light. An optical sensor or the like can be used.

The laser light source 42 is a semiconductor laser (LD), He-Ne
Any laser can be used, such as a laser or a gas laser such as an Ar laser or a C02 laser, as long as it has an emission wavelength that makes the spectral sensitivity of the photosensitive layer P1 of the photoreceptor P equal to or higher than a predetermined value. A light emitting diode (LED) can also be used if it has one.

The optical deflector 46 is not limited to a polygon mirror, ie, a rotating polygon mirror, but may be any device that can deflect laser light at a predetermined angle in a one-dimensional direction, and a galvanometer or the like may also be used.

The image processing device 52 processes the original image signal, performs image processing as an analog signal or digital signal to suit laser exposure, and finally sends the analog image signal to a modulation circuit 50 that drives the optical modulator 44. There is no particular restriction as long as it can be supplied as

Further, the original original image signal may be an image information signal photoelectrically read from the original, for example, a completed draft manuscript, or may be an image information signal read from a computer, video, television, C
Image information signals input from various media such as AD/CAM cameras, image and character information signals input from drawing machines, computer typesetting machines, word processors, scanners, etc., and image and character information signals that have already been converted into electrical signals, such as optical disks, CDROMs, magnetic disks, etc. It may be an image information signal stored in a storage medium such as a magnetic tape as a database, or it may be an image information signal obtained by processing these signals with a computer or the like to create a manuscript. The information signal may be an analog signal or a digital signal.

That is, the image processing device 52 referred to here includes a reading device that reads the original document image signal, a computer that processes various image information signals to produce a complete document, and each of the devices described above. The modulation circuit 5 may be connected to these devices and simply receive the original original image signal.
0 as an analog image signal.

A conveyance guide 54 is disposed between the exposure section 16 and the development section 18, and the entrance side conveyance rollers 56a, 56b of the development section 18
The photoreceptor P is suitably guided. This conveyance guide 54 is connected to the photosensitive layer P1 of the photoreceptor P on which the electrostatic latent image is formed.
Since it comes into contact with the side surface, it must have appropriate smoothness and insulation.

The developing section 18 includes an entrance conveyance roller 56a.

56b, and exit side squeeze and conveyance rollers 58a and 58b.
and 2 forming a jet nozzle 60 for liquid toner developer F.
a back electrode 64 arranged on the back side of the photoconductor P and forming a transport path for the photoconductor P with the electrodes 62, 62, a tank 66 containing liquid toner developer F, and a liquid A liquid toner developer ejection means 68 for ejecting toner developer F from an ejection nozzle 60. When the photoreceptor P is conveyed to the developing section 18 with the photosensitive layer P1 facing downward, the charged toner particles in the liquid toner developer F ejected from the ejection nozzle 60 by the ejection means 68 are transferred to the electrodes 82.62. Toner development is performed by adhering a predetermined amount to an image area where an electrostatic latent image is formed depending on the electric field strength between the photoreceptor P and the photosensitive layer P1.

The liquid toner developer used in the present invention is not particularly limited, and any developer used in conventional wet development can be used. In other words, the liquid toner used in normal wet development uses a petroleum-based odorless solvent as a liquid medium to produce images containing fine organic and inorganic pigments, dyes, etc. classified into the required particle size range. Particles to be formed and additives such as charge control agents and dispersion stabilizers are added. When an electrophotographic photoreceptor having an electrostatic latent image is immersed in this,
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 onto the latent image and developed.

As such a liquid developer, for example, one in which colored or non-colored polymer or copolymer particles are dispersed in an insulating solvent such as a paraffin solvent (for example, Isopar G, Isopar H) is used. If you do,
A pigment such as carbon black coated with a polymer or copolymer is used. Additionally, the liquid toner developer can contain various additives used in the art, such as dispersants.

Examples of such liquid toner developers include 11, for example, a toner developer ELP (manufactured by Fuji Photo Film Co., Ltd.) that typically contains positively charged toner particles in a paraffin solvent.
can be mentioned.

Here, a voltage having a polarity opposite to that of the charge on the photosensitive layer P1 may be applied between the electrode 62 and the back electrode 64 in order to reduce toner fog in the non-image area.

The fixing section 20 is for fixing a toner image on the photoconductor P which has been developed with toner by the development section 18 and has had excess liquid toner developer squeezed out by its exit conveyance rollers 58a and 58b. It consists of heaters 70 and 72 arranged on both sides of the conveyance path.

The heaters 70 and 72 may be of any type as long as they can dry the photoreceptor P and heat and fix the toner image formed on the photosensitive layer P1 of the photoreceptor P. For example, a lamp heater, a panel heater, or the like may be used. Although the heater 72 does not need to be provided, it is preferable to provide it in order to increase the drying speed and fixing speed.

In front of the fixing section 20, a take-out roller rough 4a is provided.

74b is provided, and the photoreceptor P on which the toner image has been fixed in the fixing section is conveyed by take-out rollers 74a and 74b and sent out to a take-out tray 76 that protrudes outside from the main body of the electrophotographic engraving apparatus 10.

Thereafter, the photoreceptor P having this toner image is subjected to a hydrophilic treatment using an etching liquid to form a printing original plate, that is, a printing plate.

In the electrophotographic engraving apparatus 10 of the present invention, the pull-out roller 24a pulls out the photoreceptor P.

24b, conveying rollers 30a, 30b, 56a,
56b, 58a, 58b, take-out rollers 74a, 74b and nip rollers 36.38 are - numerically carbon-containing acrylonitrile butadiene rubber (NBR);
A roller made by the company is used. This is because the rubber hardness of NBR is moderate at about 50 to 60 degrees because it contains carbon, and is suitable for conveying the photoreceptor P.

The material of the roller used in the present invention may be any material as long as it does not damage the photosensitive layer P1 of the photoreceptor P and has appropriate hardness. rubber, EPT rubber (ethylene propylene terpolymer (EPM%EPDM) rubber), and the like.

Although the electrophotographic engraving apparatus 10 of the present invention shown in FIG. 1 does not have an etching section for engraving the non-image area of the developed electrophotographic photoreceptor P, it is different from the conventional one shown in FIG. The device may include an etching section, such as an electrophotographic device.

EXPERIMENTAL EXAMPLES> The electrophotographic engraving apparatus of the present invention will be specifically explained below using experimental examples.

(Experiment Example 1) In the electrophotographic engraving apparatus 10 shown in FIG.
The relationship between m) and charging speed (1 m+11/5IIC) was investigated.

(i) The voltage applied to the corona charger 32 is 8kV and 6k
v, the 100% value of the highest charging value (6kV only) and 9
Measurements were made for the 0% value. The electrophotographic photoreceptor P used here was an electrophotographic master ELP Mark II, and the surface resistivity of the back surface was 1.02×10′Ω.

The results are shown in Figure 3a.

As is clear from the figure, if the distance 111D is 50 mm or less, the charging speed is 25 cm/sec or less, and the charging speed is 90 cm/sec or less.
% charge value could be achieved without fail, and even 100% charge value could be achieved at a charging speed of 20 B/sec or less. By setting the distance 111D to about 15 mm, a 100% charging value could be achieved even at a charging speed of 25 mm/sec or less.

(ii) When the voltage applied to the corona charger 32 is 8 kV, the surface resistivity of the back side is 1.02 x 10 6 Ω, 5.0
Using an electrophotographic photoreceptor P having a resistance of X10'Ω and 2.43X1010Ω,
Measurements were made for the 0% value.

The results are shown in Figure 3b.

As is clear from the figure, when the surface resistivity of the back surface of the photoreceptor is 5X10''Ω or less, the maximum charging value and 90% value are determined by the distance @D compared to when it is 2.43X1010Ω.
If they are the same, a high charging speed can be obtained, and if the charging speed is the same, a large distance can be obtained. In particular, in the case of 5X10'Ω or less, the distance HD is 50 mm or less and the charging speed is 25 m.
m/sec, 90% chargeability can be achieved without fail.

(Experiment Example 2) In the electrophotographic engraving apparatus 10 of the present invention shown in FIG.
The conveying roller 30a that contacts the back surface of the photoreceptor P is a metal roller made of aluminum, and the distance 1iD between the clamping point of the conveying rollers 30a, 30b and the corona charger 32 is 20 mm.
And so.

Further, the voltage applied to the corona charger 32 was -6.5 kV. The surface resistivity of the back surface of the electrophotographic photoreceptor P used was 108Ω. Further, the sub-scanning conveyance speed of the photoreceptor P was 5 mm/sec.

At this time, the surface potential of the photosensitive layer surface of the photoreceptor P was 480 .mu.m.

(Reference Example 1) In 10 shown in FIG. 1, the conveyance roller 30a that contacts the back surface of the photoconductor P is made of NBR, and a similar corona charger is arranged at a position opposite to the corona charger 32 with the photoconductor P in between. A charging test was conducted in the same manner as in Example 1 except that the double corona method was used. The applied voltage of the double corona charger was -6.5 kV.

At this time, the surface potential of the photosensitive layer P1 side of the electrophotographic photoreceptor P was 480V.

(Reference Example 2) The corona charger on the back side of the photoconductor P in Reference Example 1 is connected to the photoconductor P.
A charging test was conducted in exactly the same manner as in Reference Example 1, except that the static elimination brush was changed to be in contact with the back surface of the sample.

At this time, the surface potential of the electrophotographic photoreceptor P on the photosensitive layer P1 side was 480V.

As mentioned above, as is clear from the results of Example 2 and Reference Examples 1 and 2, the charging section of the electrophotographic engraving apparatus of the present invention is of a single corona type, and is brought into contact with the back surface of the photoreceptor of the upstream conveyance roller pair. By simply using a metal roller as the roller, it was possible to achieve a charging potential completely equivalent to the conventional double corona method of Reference Example 1 and the single corona method using a conventional static elimination brush of Reference Example 2.

<Effects of the Invention> As described in detail above, according to the present invention, a corona charger is disposed only on the photosensitive layer surface side of the electrophotographic photoreceptor in the charging section, and is isolated for a predetermined period on the upstream side of the corona charger. Of the pair of conveyance rollers that hold and convey the photoreceptor, a simple configuration in which the conveyance roller that contacts the back surface of the photoreceptor, that is, the support, is a roller made of a conductive material allows corona charging to occur on both the front and back surfaces of the photoreceptor. Even in the conventional double corona method and the single corona method, a grounding member such as a metal roll or a static elimination brush that contacts the back side of the photoreceptor is placed at a position facing the corona charger across the photoreceptor. The charging potential is exactly the same as the conventional single corona method (
It is possible to obtain a printing original plate on which a high-quality toner image of sufficient density without unevenness is formed without a decrease in toner image density when toner development is performed after laser exposure.

Therefore, the number of components of the charging section can be reduced! This makes it possible to downsize and reduce the cost of the electronics section and, by extension, of the entire electrophotographic device.

Therefore, by treating the photoreceptor on which the thus obtained toner image is formed with a hydrophilic treatment using an etching liquid, a high-quality printing original plate, which has a toner image of sufficient thickness and excellent printing durability, can be produced. A printing plate can be obtained, and printed matter printed by this printing plate can have a high-quality image.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an embodiment of an electrophotographic engraving apparatus according to the present invention. FIG. 2 is a sectional view showing the structure of an electrophotographic photoreceptor used in the electrophotographic engraving apparatus of the present invention. FIGS. 3a and 3b show the distance 1! between the corona charger of the charging section of the electrophotographic engraving apparatus of the present invention and the clamping point of the pair of upstream transport rollers! It is a graph showing the relationship between iD and charging speed. ′! Figure J4 is a schematic cross-sectional view of one embodiment of a conventional electrophotographic engraving apparatus. Explanation of symbols 10... Electrophotographic engraving device, 12... Photoreceptor supply section, 14... Charging section, 16... Exposure section, 18... Developing section, 20... Fixing section, 22 ... Magazine, 22a... Ejection port, 24a, 24b... Pull-out roller, 26... Cutter, 28... Conveyance guide, 30a, 30b... Conveyance roller, 32... Corona charger, 34 ...Writing drum, 34a...Exposure position, 36.38...Nip roller, 40...Photoconductor detection sensor, 42...Laser light source, 44...Light modulator, 46...Light Deflector, 48... Scanning lens, 50-... Modulation circuit, 52... Image processing device, 54... Conveyance guide, 56a, 56b... Inlet side conveyance roller, 58a, 58
b...Output conveyance roller, 60...Ejection nozzle, 62.62-...Electrode, 64...Back electrode, 66...Tank, 68...Ejection means, 70.72... Heater, 100... Electrophotographic engraving device, 102... Sensitive material supply unit, 104... Pulling roller, 106-... Cutter, 108... Corona charger, 110... Photographing unit, 112- ...Original table, 114...Mirror 116...Lens, 118...Developing section, 120...Fixing section, 122...Etching section, 124...Ejecting port, P...Electronic photograph Photosensitive material, S... Original manuscript FIG, 2 FIG, 3a 90% value charging speed of Izumi high value (mm 1 sec) FIG, 3b Charging speed (mm/sec) Procedure report (self-produced) Heisei March 28, 2002 1. Display of the case 1999 Patent Application No. 84278 2. Name of the invention Electrophotographic printing device 3. Person making the amendment Relationship to the case Patent applicant name (520) Fuji Photo Film Co., Ltd. 4,
Agent Address: 4th Floor, Chiyoda Iwamoto Building, 3-2-2 Iwamoto-cho, Chiyoda-ku, Tokyo 101 8864-4498 Fax: 864-6280 "Detailed Description of the Invention" and "Brief Description of Drawings" in the Specification
Each column and drawing (Figure 1) 6. Contents of amendment (1) "Preferred,
" should be corrected to "preferably, more preferably 5×10'Ω or less." (2) Insert "preferably 5 x 10'Ω or less" after "less than" on page 11, line 13. (3) r on page 13, line 20 is preferred. " should be corrected to "preferably, more preferably 5×10'Ω or less." (4) Insert "(both manufactured by Fuji Photo Film ■)" after "Mark +1 J" on page 14, line 20. (5) On the second and third lines of page 17, "When clamped, the conveyance roller" is "clipped and conveyed." After a predetermined period of time after the photoconductor detection sensor 40 detects the tip of the photoconductor P. (For example, if the tip of the photoreceptor P is at the nip roller 3
6.38 and the writing drum 34)
, conveyance roller”. (6) Insert "Made of conductive material, for example" in front of "Made of metal" in the 4th line of page 18. (7) Change the distance between 1 and 1 on the 8th line of page 18 to the distance between (
interval)”. (8) “This distance...” on page 18, lines 9-10.
``It is preferable, but'' ``It is preferable that this interval be narrower.By the way, it is corrected to ``It is conventional and normal''. (9) On page 18, line 12, after “of photoreceptor P”, “
Insert "" on the back. (10) In the 1st to 5th lines of page 20, ``When the photoconductor detection sensor is inserted),'' is corrected to ``When the photoconductor P is transported.'' (11) In the fifth line of page 21, ``, the fixing unit 20J is corrected to ``and in the fixing unit 20''. (12) "Media" in line 18 of page 22 is corrected to "media." (13) Insert "Development" before "electrode" on page 24, line 7, 's8, line 17, \S26S26, line 8, and page 36, line 12. (14) Delete "odorless" on page 25, line 5. (15) "Photosensitive layer..." on page 18, lines 9-10 of the same
. . Voltage" is corrected to "voltage so that the developing electrode 62 has the same polarity as the charge on the photosensitive layer P1." (16) Delete "r30a," on page 27, line 16. (17) “Terpolymer (EP)” on page 28, line 10 of the same
M, EPDM) Delete J. (18) Insert "(manufactured by Fuji Photo Film ■)" after "Mark II J" on page 29, line 14. (19) "Photosensitive material" on page 37, line 10 is corrected to "photoreceptor." (20) Figure 1 of the drawing is corrected as shown in the attached sheet.

Claims (1)

[Claims] (1) a charging unit for uniformly charging an electrophotographic photoreceptor having a photosensitive layer containing a photoconductive substance and a support supporting the photosensitive layer; and an exposure unit for exposing the photoreceptor to light; A developing unit for developing toner on the exposed photoreceptor, and a fixing unit for fixing the developed photoreceptor, and continuously performs charging, exposure, development, and fixing while transporting the photoreceptor to form a printing original plate. An electrophotographic engraving apparatus, in which a corona charger provided in the charging section is disposed only on the photosensitive layer side of the photoreceptor, and a corona charger is provided on the transport upstream side of the corona charger at a predetermined interval, and 1. An electrophotolithography apparatus, characterized in that, of a pair of conveyance rollers for pinching and conveying a body, a conveyance roller on the support side of the photoreceptor is made of a conductive material.