JPH09160326A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a color image forming device by fixing an electrifying means on the upper side or underside of a developing means, and forming a color image in such a manner that electrification, image exposure, and development are carried out in order within the one rotation of an image forming body. SOLUTION: Around the rotary photoreceptive drum 10, developing units 13 are arranged in color order. The Y and M developing units 13 are arranged on the left of the photoreceptive drum 10, and the C and K developing units 13, on the right of the photoreceptive drum 10, in the direction of the rotation of the photoreceptive drum 10, shown by an arrow. Y and M scorotron electrifiers 100 are arranged on the underside 132a of the developing casing 132 of the Y and M developing units 13, and Y and M scorotron electrifier 100 are arranged on the upper side 132b of the developing casing 132 of the C and K developing units 13, and each of them is fixed by a screw 135. Because the scorotron electrifiers as developing means and electrifying means for the separate colors are integrated, space can be saved and the color image forming device can be miniaturized.

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 such as a copying machine, a printer, a facsimile, etc., in which a plurality of sets of charging means, image exposing means and developing means are arranged around the image forming body. The present invention relates to an electrophotographic color image forming apparatus that forms a color image by superimposing toner images during one rotation.

[0002]

2. Description of the Related Art Conventionally, as a method for forming a multicolored image, an image forming body, a charging means, a developing means, etc., which are the same in number as the colors necessary for forming an image, are provided, and a single color formed on each image forming body Image forming apparatus that forms a color image by superimposing the toner image on the transfer material to form a color image, and forms a color image by repeating charging, image exposure and development for each color by rotating the image forming body a plurality of times. There is known an apparatus or a color image forming apparatus which forms a color image by sequentially performing charging, image exposure and development within one rotation of the image forming body.

However, each of the image forming apparatuses described above is provided with the same number of image exposing means, charging means, developing means and the like as the colors required for image formation, and the monochromatic toner images formed on the photoconductors are respectively superposed on the transfer material. A color image forming apparatus for forming a color image has a drawback that the volume of the apparatus is increased because a plurality of image forming bodies and transfer materials need to be conveyed. On the other hand, by rotating the image forming body a plurality of times, each color A color image forming apparatus that forms a color image by repeating charging, image exposure, and development has a smaller volume, but has a limitation that the size of the formed image is limited to the surface area of the photoreceptor or less.

In view of this, a color image forming apparatus which forms a color image by sequentially performing charging, image exposure and development within one rotation of the image forming body has no restriction on the size of the image and is capable of high speed image formation. There are advantages such as Furthermore,
For example, JP-A-5-307307 proposes a device in which a transparent substrate is used as a substrate of an image forming body and an image exposing means is arranged inside the image forming body to downsize the apparatus.

[0005]

However, a color image forming apparatus for forming a color image by sequentially performing charging, image exposure and development within one rotation of the above-mentioned image forming body is described below.
Since it is necessary to dispose a large number of charging means outside the image forming body, there is a problem that miniaturization is difficult.

The present invention improves and solves the above problems,
An object of the present invention is to enable miniaturization of a color image forming apparatus that forms a color image by sequentially performing charging, image exposure and development within one rotation of the image forming body.

Further, there is a problem that it is difficult to downsize the apparatus because a large number of image exposing means are provided inside. Also,
When image exposure is performed on the image forming body on which the toner image is formed by the image exposing means, there is a problem that a slight amount of toner scatters from the formed toner image due to the potential attenuation of the image forming body by the image exposure light. .

According to a second aspect of the present invention, the above problems are improved, and a color image forming apparatus that forms a color image by sequentially performing charging, image exposure and development within one rotation of the image forming body can be miniaturized. It is also intended to prevent toner scattering.

[0009]

The above-mentioned object is to provide a charging means for charging the image forming body around a rotating image forming body, and an image exposure for exposing the charged image forming body to form a latent image. And a developing unit for developing a latent image formed on the image forming body to form a toner image, a plurality of sets are arranged, and the charging unit is configured to charge the image forming body during one rotation of the image forming body. After a plurality of toner images are superposed on the image forming body by sequentially repeating the formation of a toner image by charging, image exposure by the image exposing means and development by the developing means, the superposed toner images are transferred. In the color image forming apparatus for transferring all at once to the color image forming apparatus, the charging means is attached to the upper surface or the lower surface of the developing means.

[0010]

Embodiments of the present invention will be described below. Note that the description in this column does not limit the technical scope of the claims and the meaning of terms. Further, the following affirmative description in the embodiments of the present invention shows the best mode, and does not limit the meaning or technical scope of the terms of the present invention.

An image forming process and each mechanism of a color image forming apparatus according to an embodiment of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus according to an embodiment of the present invention, FIG. 2 is an enlarged cross-sectional view of an essential part of FIG. 1, and FIG. 3 is an enlarged view of an essential part of FIG. FIG. 4 is a view showing a mounting state of the charging means, and FIG.
[Fig. 3] is an assembly drawing of a charging means.

In the color image forming apparatus of this embodiment, a photosensitive drum having a conductive layer and a photosensitive layer provided on the outer peripheral surface of a transparent substrate is used as an image forming body, and an image is formed inside the photosensitive drum. The structure is such that the exposure unit is arranged outside, and the image forming process unit such as the charging unit, the developing unit, the transfer unit, the static eliminator, and the cleaning unit is arranged outside.

The photosensitive drum 10, which is an image forming body, is provided with a cylindrical substrate formed of a transparent member of transparent acrylic resin inside, and a transparent conductive layer, an a-Si layer or an organic photosensitive layer (OPC). ) Is formed on the outer circumference of the substrate, and is rotated clockwise in the state of being grounded as shown by the arrow in FIG.

In the present embodiment, it is sufficient that the photoconductive layer of the photosensitive drum has an exposure light amount capable of imparting an appropriate contrast. Therefore, the light transmittance of the transparent substrate of the photosensitive drum in the present embodiment does not need to be 100%, and may have a characteristic that some light is absorbed when the exposure beam is transmitted. As the material of the translucent substrate, an acrylic resin, particularly one polymerized using methyl methacrylate monomer, has transparency, strength, accuracy,
Acrylic, fluorine used for other general optical members, etc.
Various translucent resins such as polyester, polycarbonate, and polyethylene terephthalate can be used. The light-transmitting conductive layer was made of indium tin oxide (ITO), tin oxide, lead oxide, indium oxide, copper iodide, Au, Ag, Ni, Al, etc. A metal thin film is used, and as a film forming method, a vacuum vapor deposition method, an active reaction vapor deposition method, various sputtering methods, various CVs.
D method, dip coating method, spray coating method and the like are used.
Further, as the photoconductor layer, amorphous silicon (a
-Si) alloy photosensitive layer, amorphous selenium alloy photosensitive layer, and various organic photosensitive layers (OPC) can be used.

A scorotron charger 100 as a charging means
Is used in the image forming process of each color of yellow (Y), magenta (M), cyan (C) and black (K), and is held at a predetermined potential with respect to the above-described organic photoconductor layer of the photoconductor drum 10. The control grid and the corona discharge by the discharge electrode perform a charging action to give a uniform potential to the photosensitive drum 10.

The corona discharge electrode 101 is attached and fixed to, for example, an adhesive on the tapered surface 102a of the triangular portion of the support member 102 made of an insulating resin such as ABS resin. The control grid 105 is provided on the support member 102 in parallel with the longitudinal direction of the sharpened electrode plate 110, and the side plates 102b, 102 for attaching the control grids at both ends of the support member 102 are provided.
The scorotron charger 100 is formed by attaching and fixing to c by a resin screw (not shown).

The sharpened electrode plate 110 has a common electrode 111.
A sharpened electrode 112 which is a plurality of discharge electrodes arranged at a constant pitch with a constant interval from the common electrode 111;
It is composed of a plurality of sharpened electrodes 112 and a resistor 115 for electrically connecting the common electrode 111. The sharp electrode plate 110 is provided on the insulating substrate 120, for example, a ceramic or glass substrate, and the corona discharge electrode 101 is provided.
Is formed.

The sharpened electrode 112 and the common electrode 111 are
The tip portion 11 of the sharpened electrode 112 is formed on the insulating substrate 120 by a conductive member such as a stainless material or a copper material.
3 is provided on the insulating substrate 120 without protruding from the surface of the insulating substrate 120. The curvature of the tip portion 113 of the sharpened electrode 112 is R = 40 μm or less. The resistor 115 is provided between the sharpened electrode 112 and the common electrode 111, for example, by printing a resistor paste.
The resistance value of the resistor 115 is preferably set to approximately 1 MΩ to 100 MΩ. The control grid 105 is made by etching a single stainless plate having a plate thickness of 0.1 mm, for example.

The scorotron charger 100 described above is mounted so as to face the photosensitive drum 10, but the sharpened electrode plate 110 is mounted downstream of the photosensitive drum 10 in the rotational direction of the photosensitive drum 10. Since the discharge spreads, the charging is stable, which is preferable.

As shown in FIGS. 2 and 3, the exposure unit 12 as an image exposing means for each color is provided with a photosensitive drum 10.
The exposure position above is set to the developing casing 132 of the developing device 13.
Inside the developing sleeve 131, the developing sleeve 131 is arranged on the upstream side in the rotation direction of the photosensitive drum. By performing image exposure by the image exposure means at a position inside the developing casing, the color image forming apparatus can be downsized and toner scattering can be prevented. In particular, when reversal development is used, since the charging polarity and the toner polarity are the same, when a voltage common to the control grid is applied to the developing casing, the toner is repelled by the developing casing and the toner is scattered to the outside. Prevented and preferred.

The exposure unit 12 is a light emitting element L arranged in the main scanning direction in parallel with the axis of the photosensitive drum 10.
A linear exposure element 12a in which a plurality of EDs (light emitting diodes) are arranged in an array and a SELFOC lens 12b as an equal-magnification imaging element are configured as a unit attached to a holder (not shown). The exposure unit 12 is attached to a fixed member 20 that holds the exposure unit 12 provided inside the photoconductor drum 10, and the image data of each color stored in the memory is sequentially read from the memory so that each color can be read. Is input to each exposure unit 12 as an electric signal.

As the exposure element, other linear elements in which a plurality of light emitting elements such as FL (fluorescent substance light emission), EL (electroluminescence), PL (plasma discharge), LED (light emitting diode) are arranged in an array are used. Used. The emission wavelength of the light emitting device used in this embodiment is 600 to 9
It is in the range of 00 nm.

The developing device 13, which is a developing means for each color, contains one-component or two-component developers of yellow (Y), magenta (M), cyan (C) and black (K), respectively, and is exposed to light. A developing sleeve 131 is provided which rotates in the same direction as the rotation direction of the photoconductor drum 10 at the developing position while maintaining a predetermined gap with respect to the peripheral surface of the body drum 10.

The developing unit 13 for each color is the charging and exposure unit 12 by the scorotron charger 100 described above.
The electrostatic latent image formed on the photosensitive drum 10 by the image exposure by and is reverse-developed in a non-contact state by a non-contact developing method by applying a developing bias voltage.

In the present embodiment, the rotation of the photosensitive drum 10 indicated by the arrow in FIG. 1 is performed according to the color order in which images are formed and the arrangement of the developing devices provided on the rotated photosensitive drum in accordance with the color order. Y, M developing unit 1 with respect to direction
3 is arranged on the left side of the photosensitive drum 10, and the C and K developing devices 13 are arranged on the right side of the photosensitive drum 10, so that Y, M
The Y and M scorotron chargers 100 are provided on the lower surface 132a of the developing casing 132 of the developing device 13 and the C and K scorotron chargers 100 are provided on the upper surface 132b of the C and K developing device 132, respectively. Screw 1
It is fixed by screws 35. By integrating the developing means for each color and the scorotron charger as a charging means, space can be saved and the color image forming apparatus can be downsized. In particular, by using a sharpened electrode that can perform a narrow discharge, the size of the electric device and the size of the color image forming apparatus can be further reduced.

As the original image, an image read by an image pickup device of an image reading apparatus separate from this apparatus or an image edited by a computer is temporarily stored as image data for each color of Y, M, C and K. Store and store in.

At the start of image recording, a photoconductor drive motor (not shown) is rotated to rotate the photoconductor drum 10 in the clockwise direction shown by the arrow in FIG. 1, and at the same time, the left side of the photoconductor drum 10 is colored yellow (Y). Development casing 132 of the developing device 13
Y scorotron charger 1 placed on the lower surface 132a of the
The charging action of 00 causes the application of electric potential to the photoconductor drum 10.

After the photosensitive drum 10 is applied with an electric potential, the Y exposure unit 12 starts exposure by an electric signal corresponding to the first color signal, that is, Y image data, and the surface of the photosensitive drum 10 is exposed to light by rotational scanning of the drum. An electrostatic latent image corresponding to the Y image of the original image is formed on the layer.

The latent image is reversal-developed by the Y developing device 13 in a state where the developer on the developing sleeve is not in contact with the developer, and a yellow (Y) toner image is formed in accordance with the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 has a magenta (M) developing unit 1 on the yellow (Y) toner image and further on the left of the photosensitive drum 10 and above the yellow (Y).
An electric potential corresponding to the second color signal of the M exposure unit 12, that is, the image data of M is given a potential by the charging action of the magenta (M) scorotron charger 100 disposed on the lower surface 132a of the developing casing 132 of No. The signal exposure is performed, and the non-contact reversal development by the developing unit 13 for M forms a magenta (M) toner image on the yellow (Y) toner image in sequence.

By the same process, the developing casing 13 of the cyan (C) developing device 13 is provided on the right side of the photosensitive drum 10.
The cyan (C) scorotron charger 100, the exposure unit 12 of C, and the developing device 13 of C, which are arranged on the upper surface 132b of No. 2, further expose a cyan (C) toner image corresponding to the third color signal. Right side of body drum 10, C
The developing casing 13 of the black (K) developing device 13 at the bottom of the
The black (K) scorotron charger 100, the exposure unit 12, and the developing device 13 arranged on the upper surface 132b of No. 2 sequentially form a black (K) toner image corresponding to the fourth color signal. , Photoconductor drum 10
Within one rotation, a color toner image is formed on the peripheral surface.

These Y, M, C and K exposure units 1
Exposure of the organic photosensitive layer of the photosensitive drum 10 by 2 is performed from the inside of the drum through the transparent substrate described above. Therefore, the exposure of the images corresponding to the second, third, and fourth color signals is performed without any influence from the previously formed toner image, and the same exposure as the image corresponding to the first color signal is performed. It is possible to form an electrostatic latent image.

The developing device 13 and a predetermined value, for example, 100 μm to 10 μm from the photosensitive drum 10 are provided by an abutting roller not shown.
The developing sleeve 13a is kept in a non-contact state with a gap of 00 .mu.m, and when developing by the developing device 13 for each color.
To the photosensitive drum 10 having a transparent conductive layer grounded, a developing bias with a direct current or an alternating current applied thereto is applied to carry out jumping development with a one-component or two-component developer housed in the developing device. A non-contact reversal development for applying toner to the exposed portion is performed by applying a DC bias of the same polarity.

A transfer sheet P, which is a transfer material, is sent out from a paper feed cassette 15 which is a transfer material storage means, and is conveyed to a timing roller 16. The color toner image formed on the peripheral surface of the photoconductor drum 10 is discharged by the pre-transfer charge eliminator 100a, and then the transfer roller 14a drives the timing roller 16 to remove the toner image on the photoconductor drum 10. The image is transferred onto a transfer paper P that is a transfer material that is fed in synchronization.

FIG. 4 shows the structure of the pre-transfer charge eliminator 100a.
Although a discharge electrode having a sharpened electrode similar to the one shown in Fig. 2 is used, the discharge electrode is not necessarily limited to this, and a wire discharge electrode may be used, and an optical charge eliminator for removing charge by light exposure is used. May be. In addition, the transfer device 14a described above
A discharge electrode having a sharpened electrode having a structure similar to that shown in FIG. 4 may be used for the static eliminator 14b described later.

The transfer paper P on which the toner image has been transferred is discharged from the drum peripheral surface in the static eliminator 14b and separated from the drum peripheral surface, and then is conveyed to the fixing device 17 by the conveying belt 14e which is a conveying means. After being heated and pressed in the fixing device 17 to fuse and fix the toner on the transfer paper P, the toner is discharged from the fixing device 17, conveyed by a pair of discharge conveyance rollers 18 a, and is transferred to the upper tray of the apparatus via the discharge rollers 18. Is discharged with the toner image surface facing down.

On the other hand, the photosensitive drum 10 from which the transfer paper is separated
Is rubbed against the surface of the photoconductor drum 10 by the cleaning blade 19a in the cleaning device 19 to remove and clean the residual toner and continue to form the toner image of the original image, or temporarily stop the toner image of a new original image. Formation. The waste toner scraped off by the cleaning blade 19a and the cleaning roller 19b is discharged to the waste toner container 82 through the toner transport screw 19c and the toner transport pipe 19d.
After the cleaning is completed, the cleaning blade 19a and the cleaning roller 19b are kept apart from the photoconductor drum 10 in order to prevent damage to the photoconductor drum 10.

Another example of the charging means will be described with reference to FIG. FIG. 5 is a diagram showing another example of the charging means.

In the scorotron charger 200 as the charging means of this embodiment, the triangular portion of the supporting member shown in FIG. 3 has a U shape, and as shown in FIG.
The pointed electrode 1 is formed on the insulating substrate 120 in the U-shaped portion of 2.
The corona discharge electrode 101 provided with 12 and the control grid 105 are attached. The mounting method to each developing device 13 is the same as that in the above-described embodiment, and the developing means for each color and the scorotron charging device as the charging means are integrated so that space saving is achieved and a color image forming apparatus is provided. Can be miniaturized. Further, when a specific developing device is replaced, the corresponding scorotron charger can be replaced at the same time.

A cleaning means for cleaning the sharpened electrode of the charging means using the sharpened electrode described in FIG. 4 will be described with reference to FIG. FIG. 6 is a diagram showing a cleaning means for cleaning the sharpened electrode.

The cleaning means 300 comprises a supporting member 10.
The slide member 301 that slides around slide shafts 303 and 304 that are fixed to the side plates 102b and 102c on both ends of 2 and the sharpened electrode 112 of the corona discharge electrode 101 provided on the insulating substrate 120 during sliding. The cleaning pad 302 for cleaning the sharpened electrode 112, and the actuating rod 305 having one end fixed to the slide member 301 and the other end that can be pulled out by receiving the side plate 102c (not shown).

When the slide member 301 is moved left and right by the actuating rod 305 as shown by the arrow in FIG. 6, the cleaning pad 302 slides on the sharpened electrode 112 to clean the sharpened electrode 112. At this time, the cleaning pad 302 not only cleans the sharpened electrode 112, but also the whole sharpened electrode plate 110 or the sharpened electrode plate 110.
The entire insulating substrate 120 provided with may be rubbed for cleaning.

In the above-described embodiment of the present invention, the discharge electrode having the sharpened electrode shown in FIG. 4 is used as the structure as the charging means attached to the developing means. The structure may use a sharpened electrode plate in which the tip of the sharpened electrode protrudes from the flexible substrate, or may use a wire discharge electrode.

In the present invention, by providing the image exposure means inside, the charging means and the developing means can be arranged close to each other. When the image exposure unit is provided outside the image forming body, the charging unit and the developing unit are integrated by using an optical system such as a laser optical system that can perform exposure even in a narrow width between the charging unit and the developing unit. It can be configured.

[0045]

According to the first aspect of the present invention, it is possible to miniaturize a color image forming apparatus which forms a color image by sequentially performing charging, image exposure and development within one rotation of the image forming body.

According to the second aspect of the invention, the color image forming apparatus is downsized and the toner scattering is prevented by performing the image exposure of the image exposing means at the position inside the developing casing.

According to the third aspect of the present invention, by using the sharpened electrode which discharges particularly narrowly, the size of the electric device can be reduced,
In addition, the size of the color image forming apparatus can be further reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is an enlarged view of a main part of FIG. 2, showing a mounting state of a charging unit.

FIG. 4 is an assembly diagram of a charging unit.

FIG. 5 is a diagram showing another example of a charging unit.

FIG. 6 is a view showing a cleaning means for cleaning a sharpened electrode.

[Explanation of symbols]

 10 Photoreceptor Drum 12 Exposure Unit 13 Developer 100,200 Scorotron Charger 101 Corona Discharge Electrode 102,202 Support Member 110 Sharpened Electrode Plate 112 Sharpened Electrode 120 Insulating Substrate 132 Developing Casing 300 Cleaning Means 301 Slide Member 302 Cleaning Pad

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuuo Endo 2970 Ishikawa-cho, Hachioji, Tokyo Konica stock company (72) Inventor Toru Komatsu 2970 Ishikawa-cho, Hachioji, Tokyo stock Konica stock company

Claims (3)

[Claims] A charging unit configured to charge the image forming body around the rotating image forming body; an image exposing unit configured to perform image exposure on the charged image forming body to form a latent image; And developing means for developing the formed latent image to form a toner image, wherein during one rotation of the image forming body, the image forming body is charged by the charging means and the image is formed by the image exposing means. A color image in which a plurality of toner images are superimposed on the image forming body by sequentially repeating formation of a toner image by exposure and development by the developing unit, and then the superimposed toner images are collectively transferred to a transfer material. In the forming device,
A color image forming apparatus, wherein the charging means is attached to an upper surface or a lower surface of the developing means. 2. The color image forming apparatus according to claim 1, wherein the image exposing unit is arranged inside the image forming body and performs image exposure at a position in a developing casing of a corresponding developing unit. apparatus. 3. The color image forming apparatus according to claim 1, wherein the charging unit has a sharpened electrode as a discharge electrode.