JPH11143217A - Color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain a thin-shaped developing means by installing a developer layer forming means and a developer recovering means so that they may be relatively arranged oppositely to a horizontal plane passing through the center of a developer carrier while forming each specified angle in a direction separated from an image forming body with respect to a vertical plane passing through the center of the developer carrier. SOLUTION: In a Y and M developing unit 13a, the developer is scraped by a scraper 134a at the upper side part of a developing sleeve 131, then, the developer is carried on to a supply roller 135a and near a stirring screw 136. The developer is supplied to the developing sleeve 131 again by a thin layer forming bar 133 installed just under the scraper 134a and in the lower side part of the developing unit 13a. In this case, the thin layer forming bar 133 as the developer layer forming means and the scraper 134 as the developer recovering means are relatively arranged oppositely to the horizontal plane passing through the center of the developing sleeve 131 as the developer carrier while forming the angle α and β in a direction separated from a photoreceptor drum 10 as the image forming body with respect to the vertical plane passing through the center of the developing sleeve 131.

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 one method of forming a multi-color image, a color image is formed by sequentially charging, exposing and developing a plurality of colors within one rotation of one image forming body. Image forming apparatuses are known.

[0003] However, the above-mentioned color image forming apparatus is capable of forming a high-speed image in a method of forming a multi-color image, but the charging means, the image exposing means and the developing means within one rotation of the photosensitive member. And the image exposure means may be stained by toner leaking from the developing means which is close to the image exposure means, thereby deteriorating the image quality. To avoid this, it is necessary to increase the distance between the image exposure means and the developing device. For this reason, there is a disadvantage that the diameter of the photoreceptor is inevitably increased and the size of the apparatus is increased. For the purpose of avoiding this drawback, the substrate of the photoreceptor is formed of a translucent material, and a plurality of image exposure means are accommodated therein, and an image is exposed to the photoreceptor layer formed on the outer periphery thereof through the substrate. For example, an apparatus of the type is proposed in Japanese Patent Application Laid-Open No. 5-307307.

[0004]

However, in the color image forming apparatus proposed above, a plurality of image exposing means are accommodated in the image forming body to reduce the size, but the charging means and the charging means are provided on the outer periphery of the image forming body. It is necessary to arrange a large number of developing means, and the configuration of the arrangement is difficult. In particular, the developing means tends to be thick due to the developer layer forming means and the developer collecting means provided in the developing means, and the space occupied by the developing means is large,
Four sets of developing means arranged horizontally in parallel with the central axis of the photosensitive drum as an image forming body, and charging means arranged respectively upstream of the four sets of developing means in the rotation direction of the image forming body. The problem of interference occurs.

Further, the thick developing means increases the ratio of the developer transport provided in the developing means to the developer tank, so that the driving torque of the developer transport is large and uniform rotation of the developer transport is obtained. There is also the problem of not being able to do so. Further, there is a problem that the life of the developer is shortened due to the deterioration of the developer.

An object of the present invention is to provide a color image forming apparatus which solves the above problems, reduces the thickness of the developing means, and reduces the driving torque of the developer conveying member.

[0007]

The above object is achieved by providing a plurality of charging means and developing means on the outer peripheral surface of the image forming body and a plurality of image exposing means on the inner peripheral surface of the image forming body. During one rotation, charging of the image forming body by the charging unit, formation of a latent image by image exposure by the image exposing unit, and development of the latent image by the developing unit are repeated, and the periphery of the image forming body is rotated. In a color image forming apparatus that forms a color toner image by superimposing a plurality of toner images on a surface, a vertical plane passing through the center of the image forming body is located on the upstream side and the downstream side in the rotation direction of the image forming body. Two sets of developing means are vertically arranged, and the developer layer forming means and the developer collecting means provided in the developing means are arranged with respect to a vertical plane passing through the center of a developer carrier provided in the developing means. In the direction away from the image forming body Forms a degree α and beta, are achieved by a color image forming apparatus characterized by disposing relative to a horizontal plane passing through the center of the developer conveying member.

[0008]

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. Also, the following assertive description in the embodiment of the present invention indicates the best mode, and does not limit the meaning of the terms of the present invention or the technical scope.

An image forming process and each mechanism of an embodiment of the color image forming apparatus of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional configuration diagram of an embodiment of the color image forming apparatus of the present invention, FIG. 2 is a diagram showing a configuration of an image exposure unit of FIG. 1, and FIG. 3 is a perspective view of FIG. FIG. 4 is a cross-sectional configuration diagram of the image forming body of FIG. 1, FIG. 5 is a cross-sectional configuration diagram of a developing unit disposed on the right side of FIG. 1, and FIG. FIG. 3 is a cross-sectional view of a developing unit to be used.

Referring to FIGS. 1 to 4, a photosensitive drum 10 as a drum-shaped image forming member is, for example, a cylindrical light-transmitting resin substrate formed of a light-transmitting member made of a light-transmitting acrylic resin. Is provided inside, and a translucent conductive layer and an organic photoreceptor layer (OPC) are formed on the outer periphery of the substrate.
It is rotated in the direction 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 that can provide an appropriate contrast. Therefore, the light transmittance of the light-transmitting resin substrate of the photosensitive drum in the present embodiment does not need to be 100%, and may have a characteristic such that a certain amount of light is absorbed when the exposure beam is transmitted. . As the material of the light-transmitting substrate, an acrylic resin, particularly one polymerized using a methyl methacrylate monomer, has a light-transmitting property, strength,
Although it is excellent in accuracy, surface properties, and the like, it is preferably used, but various translucent resins such as fluorine, polyester, polycarbonate, polyethylene terephthalate, and the like used for other general optical members can be used. Also,
It may be colored as long as it has a property of transmitting the exposure light. The refractive index of these resins is approximately 1.5. As a method for forming the light-transmitting conductive layer, indium tin oxide (ITO), alumina, tin oxide, lead oxide, indium oxide can be formed by a vacuum evaporation method, an active reaction evaporation method, various sputtering methods, and various CVD methods. , Copper iodide, Au, Ag, Ni,
A light-transmitting thin film made of Al or the like is used,
A conductive resin composed of the above-mentioned metal fine particles and a binder resin is used by a dip coating method, a spray coating method or the like. Further, as the photoconductor layer, various organic photoreceptor layers (O
PC) can be used.

The following are examples of preferred image forming members.

After adding a catalyst for synthesizing and polymerizing the plastic material monomer, pour it into a cylindrical mold, seal it tightly with a side plate, fix it properly in an oil bath or hot water tank, and heat it at high speed. To promote uniform polymerization. After completion of the polymerization, the mixture is cooled, the obtained translucent resin substrate is taken out of the mold, cut and, if necessary, subjected to a finishing step to produce a transparent resin substrate for the photosensitive drum of the image forming apparatus (centrifugal weight). legal).

As a material for the light-transmitting resin substrate of a light-transmitting plastic molded by centrifugal polymerization, a material obtained by polymerizing a methacrylic acid methyl ester monomer as described above has a light-transmitting property, strength, accuracy, and surface property. In addition, polyethyl methacrylate, polybutyl methacrylate, polyethyl acrylate, polybutyl acrylate, polystyrene, polyimide, polyester, polyvinyl chloride, or the like, or a copolymer thereof can be used. In the centrifugal polymerization method, since the roundness is determined by the mold used for molding, a highly accurate substrate can be obtained. In addition, uneven thickness varies depending on rotation unevenness and viscosity during polymerization and heating conditions during polymerization.

As the conductive layer, indium tin oxide (I
TO), tin oxide, lead oxide, indium oxide, alumina,
A conductive resin obtained by mixing a resin and conductive fine particles made of copper iodide, Au, Ag, Ni, Al, or the like is used. As a film forming method, a dip coating method, a spray coating method, or the like is preferably used. .

The organic photoreceptor layer comprises a charge generating material (CGM)
And a charge transport layer (CTL) containing a charge transport material (CTM) as a main component. The organic photoreceptor layer having a two-layer structure has a low CGL, and thus has good transparency of image exposure light and is suitable for the present invention. The organic photoreceptor layer may have a single-layer structure containing a charge generation material (CGM) and a charge transport material (CTM) in one layer, and may have the single-layer structure or the two-layer structure. Usually contains a binder resin.

In the photosensitive drum having the two-layered organic photosensitive layer, the CGM contained in the CGL may be an azo pigment, an azulenium pigment, a phthalocyanine pigment which is sensitive to light from a light source such as an LED or an LD. , A perylene pigment is used, and red to infrared light (600 nm
Copper phthalocyanine pigments, titanyl phthalocyanine pigments, and the like are preferably used as the CGM of the OPC photoreceptor that is sensitive to light of about 850 nm.

As the binder resin used for CGL, a polyvinyl butyral resin or a polycarbonate resin is used, which is excellent in sensitivity, potential change upon repeated use, and the like. These binder resins can be used alone or as a mixture of two or more.

As a solvent or a dispersion medium used for forming CGL, a ketone-based or halogen-based solvent is preferably used, and the sensitivity, the potential change upon repeated use, and the like are further improved. In addition, these solvents can be used alone or as a mixed solvent of two or more kinds.

The weight ratio of CGM to the binder resin in the CGL is 100: 1 to 1000, the film thickness of the CGL is 0.01 to 10 μm, and the coating method for forming the CGL is a blade. There are various coating methods such as coating, wire bar coating, spray coating, dip coating and slide hopper coating.

Next, as the CTM contained in the CTL, hydrazone compounds, styryl compounds, benzidine compounds, stilbene compounds and the like are used.

The binder resin used in the CTL can be selected from a wide range of insulating resins as appropriate, and preferred binder resins include silicon-alkyd resins, phenol-formaldehyde resins, and poly-N- resins. Insulating resins such as vinyl carbazole and polysilane can be mentioned, and these binder resins can be used alone or in combination of two or more.

The mixing ratio of the binder resin and CTM is 1:
It is set to 10 to 500, and more preferably 1:20 to 150. The thickness of the CTL is set to 1 to 100 μm.
~ 50 μm is preferred.

As a coating method, a method similar to CGL can be used.

If necessary, an intermediate layer is provided between the organic photoreceptor layer and the conductive layer. Examples of the intermediate layer include polyvinyl chloride vinyl acetate copolymer, vinyl acetate vinyl acetate maleic acid copolymer, ethyl cellulose, carboxymethyl cellulose and the like. And a resin layer having a thickness of 0.01 to 2 μm, such as a copolymer type or modified type alcohol-soluble polyamide resin.

The use of the plastic cylindrical translucent resin substrate produced by the above-described production method enables uniform thickness, excellent cylindricality and circularity of the cylindrical substrate, and improvement of the image exposure light A photosensitive drum without a focus shift is provided.

The scorotron charger 11 serving as a charging means is used in image forming processes of yellow (Y), magenta (M), cyan (C) and black (K). A charging operation is performed on the body layer by a control grid maintained at a predetermined potential and corona discharge by a discharge wire, and a uniform potential is applied to the photosensitive drum 10.

An exposure optical system 12 as an image exposure means for each color of yellow (Y), magenta (M), cyan (C) and black (K) has an axis of the photosensitive drum 10 on a substrate 122 as an exposure system. A linear exposure element 12a in which an LED (light emitting diode) 121 as a plurality of light emitting elements arranged in a main scanning direction parallel to the above is arranged in an array, and a light converging light transmitter (trade name) as an imaging element , Selfoc lens)
2b, the selfoc lens 12b is fixed to the lens holder 12c by, for example, an adhesive indicated by a black circle in FIGS. 2 and 3, and the exposure element 12a is exposed by, for example, an adhesive indicated by a black circle. The lens holder 12c is fixed to the metal casing 12d with the exposure element 12a and the SELFOC lens 12b positioned so as to be fixed to a metal casing 12d as a holding member of the element.
Are fixed by, for example, an adhesive indicated by a black circle to constitute the exposure optical system 12. By using the metal casing 12d, the heat generated in the exposure element 12a is quickly transmitted and diffused, which affects the displacement between the exposure elements 12a due to thermal expansion and the fluctuation of the light amount, and the unevenness of the exposure element 12a. Temperature distribution and temperature rise are prevented.

Although the holding member of the exposure element is preferably a metal casing, it is not always limited to a metal member, and a casing made of resin or the like may be used.

In addition, FL (phosphor emission), EL (electroluminescence), PL (plasma discharge) and the like are used as the light emitting element.

The exposure optical system 12 for each color uses a spacer block 12e as a wedge-shaped block member, and a main scanning direction with the photosensitive drum 10 and a sub-scanning direction with respect to the rotation direction of the photosensitive drum 10 by a tool or the like in advance. The metal casing 12d and the spacer are provided on a support member 20 using a pipe-shaped hollow member such as a cylindrical pipe or a square pipe, which is a common support for the image exposure means for each color. The block 12e and the spacer block 12e and the support member 20 are fixed to each other with an adhesive indicated by a black circle in FIGS. 2 and 3, for example. With the exposure optical system 12 for each color held, the center axis of the support member 20 is aligned with the center axis of the photosensitive drum 10 so that the support member 20
0. Therefore, image exposure of the photosensitive drum 10 by the exposure optical system 12 is performed perpendicular to the central axis of the photosensitive drum 10.

The distance between the inner peripheral surface of the support member 20 and the outer peripheral surface of the substrate of the photoreceptor drum 10 is determined by the exposure optical system 1.
2, the bottom surface of the exposure optical system 12 has a circumferential surface which is always located outside the inner circumferential surface of the support member 20. The support member 20 does not need to break the cylindrical surface, the strength is maintained, and the exposure optical system 12 can be reliably held at a predetermined imaging position.

A storage unit (not shown), such as an RA, which is read by an image scanner or input by an external signal or the like.
The image signal of each color stored in M is sequentially read from the storage unit through the control unit of the apparatus main body, and input as an electric signal to the exposure optical system 12 for each color, and the LED 121
Are emitted by, for example, a pulse width modulation method (PWM method). The emission wavelength of the light emitting element used in this embodiment is in the range of 600 to 900 nm.

As described above, each of the exposure optical systems 12 is attached to the support member 20 using a hollow member in the form of a pipe and is accommodated in the base of the photosensitive drum 10. Drawn out metal casing 12d
LED1 through connector C attached to the lower end of the
21 lead wires WA are provided. Lead wire W for each color
A is pulled out of the insertion hole 20H and bundled, and the support member 2
The through-hole 30H is drawn out of the side board 30 through the through hole 30H.

Each insertion hole 20H is connected to the connector C and the lead wire W.
A, after the connection with the sealing member S
With this, the lead wire WA is closed together with the lead wire WA, thereby preventing the scattered toner and dust from entering the exposure optical system 12. Further, an adhesive or an elastic member such as urethane foam or a rubber material is filled in the insertion hole 20H to prevent intrusion of toner or dust. As the sealing material S, for example, a hardening type silicone rubber sheet is used, and each insertion hole 20H is closed by an adhesive or the like, thereby maintaining airtightness. As a result, the lead wire WA is easily connected to the fixed electrode PA along the inner peripheral surface of the support member 20 without being strongly bent. Further, the holding member of the exposure element does not receive the stress due to the lead wire WA and does not come off due to bending of the lead wire WA.

A thin hollow member made of a light metal material such as aluminum or stainless steel, preferably a cylindrical pipe or a square pipe, is used for the support member 20 which is a common support for each exposure optical system 12. Accordingly, the weight and the heat capacity of the supporting member 20 using the metallic hollow member are reduced, and the weight of the image forming unit is reduced, the heat capacity is small, the heat conductivity is good, and the temperature control is achieved. Efficiency is increased. In addition, cylindrical and prismatic pipes are also resistant to mechanical deformation.

The developing devices 13a and 13b as developing means are formed in a thin shape described later, and are located on the right side of a vertical plane PL1 passing through the central axis of the photosensitive drum 10 in FIG. The yellow (Y) and magenta (M) developing units 13a are arranged on the upstream side in the rotation direction of the photosensitive drum 10 with respect to the vertical plane PL1 passing through the central axis. Vertical surface P passing
A developing device 13b for cyan (C) and black (K) is arranged downstream of L1 in the rotation direction of the photosensitive drum 10, and yellow (Y), magenta (M), cyan (C) and black (K). One-component or two-component developer, respectively, and in the same direction as the rotation of the photoconductor drum 10 (counterclockwise rotation in FIG. 1) while maintaining a predetermined gap with respect to the peripheral surface of the photoconductor drum 10. A developing sleeve 131 (rotating clockwise in FIG. 1), which is a rotating developer conveying body, is provided.

Since the developing property differs depending on the moving direction of the developing sleeve 131 as the developer conveying body and the photosensitive drum 10 as the image forming body, all the developing sleeves 1 for each color are used.
It is preferable from the standpoint of image quality that the rotation of the photosensitive drum 31 is set to the same direction (clockwise rotation in FIG. 1) as the rotation direction of the photosensitive drum (counterclockwise rotation in FIG. 1).

The developing units 13a and 13b for each color are
Inverted development of the electrostatic latent image formed on the photosensitive drum 10 by the charging by the scorotron charger 11 and the image exposure by the exposure optical system 12 in a non-contact state by a non-contact development method by applying a developing bias voltage. I do.

The original image is obtained by temporarily storing an image read by an image sensor of an image reading apparatus separate from the apparatus or an image edited by a computer as image signals for respective colors of Y, M, C and K. And store it.

At the start of image recording, a photoconductor drive motor (not shown) is rotated to rotate the photoconductor drum 10 in the counterclockwise direction in FIG. 1, and at the same time, a Y scorotron disposed to the right of the photoconductor drum 10 The application of a potential to the photosensitive drum 10 is started by the charging action of the charger 11.

After the photosensitive drum 10 is applied with a potential, exposure is started by an electrical signal corresponding to the first color signal, that is, the Y image signal in the Y exposure optical system 12, and the surface of the photosensitive drum 10 is scanned by rotating the drum. An electrostatic latent image corresponding to the Y image of the original image is formed on the photosensitive layer.

The latent image is reversal-developed by the Y developing device 13a 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 is charged on the yellow (Y) toner image by a charging action of a magenta (M) scorotron charger 11 disposed on the right side of the photosensitive drum 10 and above Y. And exposure is performed by an electrical signal corresponding to the second color signal of the M exposure optical system 12, ie, the M image signal, and the yellow (Y) is obtained by non-contact reversal development by the M developing unit 13a. A magenta (M) toner image is sequentially superimposed on the toner image.

By the same process, the cyan (C) scorotron charger 11, the exposure optical system 12 of C, and the developing device 13b of C arranged at the upper left of the photosensitive drum 10 further correspond to the third color signal. A cyan (C) toner image is further formed by a black (K) scorotron charger 11, a K exposure optical system 12, and a K developing device 13b, which are disposed below the C on the left side of the photosensitive drum 10. A black (K) toner image corresponding to the color signal is sequentially superposed, and a color toner image is formed on the peripheral surface within one rotation of the photosensitive drum 10.

The Y, M, C and K exposure optical systems 12
Exposure to the organic photosensitive layer of the photosensitive drum 10 is performed from the inside of the drum through the above-described translucent substrate. 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 sleeve 131 is kept out of contact with the photosensitive drum 10 with a predetermined value, for example, a gap of 100 μm to 1000 μm. A developing bias to which an alternating current is applied is applied, jumping development is performed with a one-component developer or a two-component developer accommodated in the developing device, and the photosensitive drum 10 that grounds the light-transmitting conductive layer is the same as toner. Non-contact reversal development in which a DC bias of a polarity is applied and toner adheres to an exposed portion is performed.

The color toner image formed on the peripheral surface of the photosensitive drum 10 is once transferred onto the peripheral surface of the intermediate transfer belt 14 provided as an intermediate transfer means.

The intermediate transfer belt 14 serving as an intermediate transfer member is an endless rubber belt having a thickness of 0.5 to 2.0 mm, and is made of silicon rubber or urethane rubber at 10 ⁸ to 10 ¹² Ω · cm.
And a resistance value of 10 ¹⁰ to 10 ¹⁶ Ω as a toner filming preventing layer on the outside of the rubber substrate.
-It has a two-layer structure in which a fluorine coating having a thickness of 5 to 50 µm is performed in cm. This layer also preferably has a similar semiconductivity. 0.1-0.5m thickness instead of rubber belt base
m, a semiconductive polyester, polystyrene, polyethylene, polyethylene terephthalate, or the like can also be used. The intermediate transfer belt 14 has rollers 14A, 14B,
The photosensitive drum 10 is stretched between the rollers 14C and 14D, and is circulated clockwise in synchronization with the peripheral speed of the photosensitive drum 10 by the power transmitted to the roller 14D.

The intermediate transfer belt 14 has a roller 14A.
The belt surface between the roller 14B and the roller 14B is in contact with the peripheral surface of the photosensitive drum 10, while the belt surface on the outer periphery of the roller 14C is in contact with the transfer roller 15, which is a transfer member, to form a toner image transfer area at each contact point. ing.

The color toner image adhered to the peripheral surface of the photosensitive drum 10 is first subjected to intermediate transfer by applying a bias voltage having a polarity opposite to that of the toner to the roller 14B at the contact point with the intermediate transfer belt 14. The image is transferred to the peripheral surface of the belt 14. That is, the color toner image on the drum is conveyed to the transfer area without scattering the toner by the guidance of the roller 14A that is grounded,
The intermediate transfer belt 14 is applied by applying a bias voltage of kV.
It is efficiently transferred to the side.

On the other hand, the transfer paper P as the transfer material is carried out by the operation of the paper feed roller 17 of the paper feed cassette (not shown) and fed to the timing roller 18, and the color toner image on the intermediate transfer belt 14 is formed. Transfer roller 1 in synchronization with conveyance
No. 5 is fed to the transfer area.

The transfer roller 15 is connected to the intermediate transfer belt 14.
The transfer paper P fed in the counterclockwise direction is synchronized with the peripheral speed of the intermediate transfer in the transfer area formed by the nip portion between the transfer roller 15 and the roller 14C in the ground state. The color toner images are successively transferred onto the transfer paper P by applying a bias voltage of the opposite polarity to the toner of 1 to 2 kV to the transfer roller 15 in close contact with the color toner image on the belt 14.

The transfer paper P to which the color toner image has been transferred is neutralized, conveyed to the fixing device 91 via the conveyance plate 19, sandwiched and conveyed between the heat roller 91A and the pressure roller 91B, and heated. After the toner is fused and fixed, the toner is discharged to the outside of the apparatus via a discharge roller 92.

Cleaning devices 100 and 140 as cleaning means are installed on the photosensitive drum 10 and the intermediate transfer belt 14, respectively, and the blades of the respective devices are constantly pressed against each other to remove the remaining adhered toner. The surrounding surface is always kept clean.

In general, the photoconductor drum 10 may be replaced depending on the size of the apparatus and the limitations of the plurality of scorotron chargers 11, the plurality of developing devices 13a and 13b, the cleaning device 100, etc., which are installed on the outer peripheral surface of the photoconductor drum 10. Diameter 5
A drum having a diameter between 0 mm and 200 mm is preferably used. In this case, for the purpose of maintaining rigidity, the thickness of the substrate of the photosensitive drum 10 is set to 2 mm to 10 mm corresponding to the drum diameter. As the support member 20 for supporting the photosensitive drum 10 described above, the exposure optical system 12
The diameter is reduced by an amount corresponding to the image forming distance, and the outer diameter is set to 20 mm to 160 mm in the case of a cylindrical pipe, and the thickness of the support member 20 is set to 0.5 mm to 5 mm corresponding to the outer diameter, so that the strength is sufficient and Each of the exposure optical systems 12 can be set on the support member 20 with a margin.

According to FIG. 4 and FIG.
Reference numeral 0 denotes a photosensitive drum that supports the flange members 10A and 10B at the end of the photosensitive drum 10 via a bearing B1 held directly on the outer periphery and a bearing B2 held by a disk member 22 integrated with the support member 20. 10 to flange member 10
A is rotatably supported by the power of a driving gear G that meshes with an internal gear 10G provided on the inner peripheral surface of A.

With the support member 20 supporting the photosensitive drum 10, the concave portions at both end surfaces, ie, the inner peripheral surfaces, are the protrusions provided on the side substrate 30 of the apparatus main body, ie, the engaging portions 3 projecting from the inner surface.
1 and is fixed between the side substrates 30 by being inserted. When the support member 20 is held, the engagement pin 32 provided on the outer peripheral surface of the engagement portion 31 of the one side substrate 30 engages with the notch 20A on the end surface of the support member 20, and the fixing angle of the support member 20 is regulated. Each exposure optical system 12 is set at a predetermined position with respect to the apparatus main body, and a scorotron charger 1 as a charging unit disposed along the peripheral surface of the photosensitive drum 10.
The correct positional relationship is maintained with respect to the developing device 13 and the developing devices 13a and 13b as developing means.

The support member 20 is provided on the photosensitive drum 10.
A disk member 22 is coaxially and integrally provided on the side opposite to the side on which the internal gear 10G is provided, and the disk member 22 serves as a support member for supporting one bearing B2 provided between the photosensitive drum 10 and the disk member 22. Is also used.

The outer peripheral portions of the flange members 10A and 10B for holding the photosensitive drum 10 are in contact with the abutting rollers 130A as position regulating members provided on both ends of the developing sleeves 131 on the same axis. Thereby, the position of the developing sleeve 131 as the developer conveying member is regulated,
A predetermined gap is set between the peripheral surface of the developing sleeve 131 and the peripheral surface of the photosensitive drum 10.

Vertical plane PL1 passing through the central axis of the photosensitive drum
FIG. 5 shows the configuration of a developing unit 13a as a Y and M developing means disposed on the right side of FIG. 1, that is, on the upstream side in the rotation direction of the photosensitive drum 10 with respect to a vertical plane PL1 passing through the center axis of the photosensitive drum 10. This will be described with reference to FIG. A common developing unit is used for the Y and M developing units, and the Y developing unit will be described as a representative. In the following description, a two-component developer will be described as a developer, but a one-component developer may be used.

The developing sleeve 131, which is a developer conveying member, rotates the photosensitive drum 10 while keeping a predetermined gap from the peripheral surface of the photosensitive drum 10 by abutting rollers 130A provided at both ends of the developing sleeve 131 (see FIG. 1). It is rotated in the same direction (counterclockwise rotation in FIG. 5) (clockwise rotation in FIG. 1).

The fixed magnet 132 has a diameter of 15 mm to 35 m.
m, and N and S magnetic poles are alternately arranged, and are fixed concentrically with the developing sleeve 131 to apply a magnetic force to the peripheral surface of the non-magnetic sleeve.

A thin layer forming rod 133 as a developer layer forming means
Is a member that regulates the layer thickness of the two-component developer on the peripheral surface of the developing sleeve 131, is made of a magnetic material having a circular cross section of a magnetic material having a diameter of 3 to 10 mm, and is formed by an elastic member 133a. The surface is evenly pressed with a predetermined load.

A scraper 134 as a developer collecting means for removing the two-component developer from the developing sleeve 131
“a” is a plate-shaped elastic member made of, for example, SUS, urethane rubber or the like, which is provided by pressing one end of a long side of the belt in parallel with the developing sleeve 131. The two-component developer scraped off by the scraper 134a falls onto the supply roller 135a.

The stirring screws 136 and 137 rotate at a constant speed in directions opposite to each other, and stir and mix the toner and the carrier in the developing device 13 with a two-component developer containing a predetermined toner component evenly. I do. Further, the supply roller 13
The two-component developer obtained by uniformly stirring and mixing the toner components by 5a is conveyed and supplied to the pressure contact portion between the developing sleeve 131 and the thin layer forming rod 133.

The Y and M developing units 13 described with reference to FIG.
The developer a is scraped off by a scraper 134a on the upper side of the developing sleeve 131 (the right side in FIG. 5), conveyed to a supply roller 135a or near a stirring screw 136, and directly under the scraper 134a. 5 is re-supplied to the developing sleeve 131 by a thin layer forming rod 133 provided on the lower side (the right side in FIG. 5), and the developing sleeve is combined with the following arrangement angle of the thin layer forming rod 133 and the scraper 134a. A thin structure that is not substantially different from the diameter of 131 can be realized.

In the above-described Y and M developing units 13a, the thin layer as the developer layer forming means forms an angle α in a direction away from the photosensitive drum 10 with respect to a vertical plane PL2 passing through the center of the developing sleeve 131. The contact point of the forming rod 133 is arranged, and the tip of the scraper 134a as the developer collecting means is arranged at an angle β in a direction away from the photosensitive drum 10 with respect to a vertical plane PL2 passing through the center of the developing sleeve 131. . Further, both the angles α and β are set to 45 ° ± 25 °, and the thin layer forming rod 133 and the scraper 134a are opposed to each other (to the opposite sides) with respect to a horizontal plane PL3 passing through the center of the developing sleeve 131, and the photosensitive layer It is arranged on the surface opposite to the body drum 10. Angles α and β are both 4
By setting the angle to 5 ° ± 25 °, the developing device 13a is made thinner, interference with surrounding charging means is reduced, and the ratio of the developing sleeve 131 immersed in the developer tank is reduced to 1 / one of one circumference.
By reducing it to about 3, the driving torque of the developing sleeve 131 is reduced, uniform rotation is achieved, and the life of the developer is prolonged.

In the above case, when a one-component developer is used as the developer, a cylindrical toner supply member using a disk-shaped plate or a brush (not shown) is used instead of the stirring screws 136 and 137. .

Next, the photosensitive drum 10 is disposed on the left side of the vertical plane PL1 passing through the central axis of the photosensitive drum 10 in FIG. 1, that is, on the downstream side in the rotation direction of the photosensitive drum 10 with respect to the vertical plane PL1 passing through the central axis of the photosensitive drum 10. The configurations of the C and K developing units will be described with reference to FIG. A common developing unit is used for the developing units of C and K, and the developing unit of K will be described as a representative. Members having the same functions and structures as those of the Y and M developing units described with reference to FIG.
The same reference numerals are given. In the following description, a two-component developer will be described as a developer, but a one-component developer may be used.

The developing sleeve 131, which is a developer transporting member, rotates the photosensitive drum 10 while keeping a predetermined gap with respect to the peripheral surface of the photosensitive drum 10 by abutting rollers 130A provided at both ends of the developing sleeve 131. It is rotated in the same direction (counterclockwise rotation in FIG. 6) (clockwise rotation in FIG. 1).

The fixed magnet 132 has a diameter of 15 mm to 35 m.
m, and N and S magnetic poles are alternately arranged, and are fixed concentrically with the developing sleeve 131 to apply a magnetic force to the peripheral surface of the non-magnetic sleeve.

A thin layer forming rod 133 as a developer layer forming means
Is a member that regulates the layer thickness of the two-component developer on the peripheral surface of the developing sleeve 131, is made of a magnetic material having a circular cross section of a magnetic material having a diameter of 3 to 10 mm, and is formed by an elastic member 133a. The surface is evenly pressed with a predetermined load.

A collection roller 134 serving as a developer collection means for removing the two-component developer from the developing sleeve 131.
Reference numeral b denotes an elastic roller member made of, for example, foamed urethane rubber and provided in parallel with and in pressure contact with the developing sleeve 131. The developing sleeve 13 is moved by the collecting roller 134b.
The developer scraped from 1 is conveyed to the stirring screw 136 by the collection roller 134b so as not to stay at the bottom of the developing device 13b.

The agitating screws 136 and 137 rotate at a constant speed in directions opposite to each other, agitate and mix the developer conveyed by the collection roller 134b, the toner and the carrier in the developing device 13, and form a predetermined toner component. And a supply roller 135b provided above the recovery roller 134b with the partition plate 139 as a partition.
Feed to The two-component developer obtained by uniformly stirring and mixing the toner components by the supply roller 135b is
1 and the thin layer forming rod 133 are conveyed and supplied to the press contact portion.
When the developer is a one-component developer, the collection roller 134b functions as a memory removal roller.

The C and K developing units 13 described with reference to FIG.
6B, the developer is scraped off by a collecting roller 134b at the lower side (left side in FIG. 6) of the developing sleeve 131, is conveyed to the vicinity of the stirring screw 136, and is supplied to the supply roller 135.
b, and is supplied to the developing sleeve 131 again by a thin layer forming rod 133 provided on the upper side (left side in FIG. 6) of the developing device 13b just above the collecting roller 134b. In combination with the arrangement angle of the rod 133 and the collection roller 134b, a thin structure that is not substantially different from the diameter of the developing sleeve 131 can be realized.

In the above-described C and K developing units 13b, a thin layer forming means serving as developer layer forming means is formed by forming an angle α in a direction away from the photosensitive drum 10 with respect to a vertical plane PL2 passing through the center of the developing sleeve 131. Arrange the contact points of the rod 133,
The contact point of the collecting roller 134b, which is a developer collecting means, is arranged at an angle β in a direction away from the photosensitive drum 10 with respect to a vertical plane PL2 passing through the center of the developing sleeve 131. Further, the angles α and β are both 45 ° ± 25 °, and the thin layer forming rod 133 and the collection roller 134b are opposed to each other (on the opposite sides) with respect to a horizontal plane PL3 passing through the center of the developing sleeve 131, and Photoconductor drum 10
And placed on the opposite side. Angles α and β are both 45 ° ±
By setting the angle to 25 °, the developing device 13b is made thin,
The interference with the surrounding charging means is reduced, and the ratio of the developing sleeve 131 immersed in the developer tank can be reduced to about ３ of one round, the driving torque of the developing sleeve 131 is reduced, and uniform rotation is achieved. In addition, the life of the developer can be extended.

In the above, when a one-component developer is used as the developer, a cylindrical toner supply member using a disk-shaped plate or brush (not shown) is used instead of the stirring screws 136 and 137. .

[0079]

According to the first or second aspect of the present invention, the thickness of the developing means is reduced, the interference with the surrounding charging means is reduced, and the ratio of the developer carrier immersed in the developer tank of the developing means is reduced. The driving torque of the developer conveying member is reduced, so that the uniform rotation of the developer conveying member and the life of the developer are prolonged.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a configuration of an image exposure unit in FIG. 1;

FIG. 3 is a perspective view of FIG. 2;

FIG. 4 is a cross-sectional configuration diagram of the image forming body of FIG. 1;

FIG. 5 is a cross-sectional configuration diagram of a developing unit disposed on the right side of FIG.

FIG. 6 is a cross-sectional configuration diagram of a developing unit disposed on the left side of FIG. 1;

[Explanation of symbols]

 Reference Signs List 10 photoconductor drum 11 scorotron charger 12 exposure optical system 13a, 13b developing device 131 developing sleeve 132 fixed magnet 133 thin layer forming rod 133a elastic member 134a scraper 134b recovery roller 135a, 135b supply roller 136,137 stirring screw PL1, PL2 vertical Plane PL3 horizontal plane

Continuing on the front page (72) Inventor ▲ Hama ▼ Shuta Ta 2970 Ishikawacho, Hachioji-shi, Tokyo Konica Corporation

Claims (2)

[Claims] 1. An image forming apparatus comprising: a plurality of charging means and developing means on an outer peripheral surface; and a plurality of image exposing means on an inner peripheral surface, each of which includes four sets of image exposing means. The charging of the body by the charging unit and the formation of the latent image by image exposure by the image exposure unit and the development of the latent image by the developing unit are repeated, and a plurality of toner images are superimposed on the peripheral surface of the image forming body. In a color image forming apparatus for forming a color toner image together, two sets of developing means are respectively arranged on the upstream side and the downstream side in the rotation direction of the image forming body with respect to a vertical plane passing through the center of the image forming body. And the developer layer forming means and the developer collecting means provided in the developing means are angled in a direction away from the image forming body with respect to a vertical plane passing through the center of a developer carrying body provided in the developing means. forming α and β, A color image forming apparatus, wherein the color image forming apparatus is disposed so as to face a horizontal plane passing through the center of an image agent transporter. 2. The color image forming apparatus according to claim 1, wherein said developer layer forming means and said developer collecting means are arranged at angles α and β of 45 ° ± 25 °.