JP2003098843A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tandem-type image forming device of, capable of coping with the requirement for making it more compact in size. SOLUTION: An intermediate transfer cleaning device 900 is a proximity member, disposed close to the outside of the peripheral surface of an intermediate transfer belt 501. A cleaning roller 20 is a deflection member which presses from the outer peripheral side, a section of the intermediate transfer belt 501 which is bridged in between two rollers among a plurality of rollers, such as a belt drive roller 508 and a driven roller 509, so that the section of the intermediate transfer belt 501 is deflected toward the inside of the belt. The intermediate transfer cleaning device 900 is arranged so that at least a part of it is housed in the space generated, when the section is deflected by the cleaning roller 20.

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 facsimile and a printer, and more specifically, a latent image carrier for carrying an electrostatic latent image and a surface of the latent image carrier. Charging means for charging, latent image forming means for forming an electrostatic latent image on the latent image carrier, developing means for developing the electrostatic latent image into a toner image, A plurality of image forming means having a transfer means for transferring the toner image on the latent image carrier onto a belt-shaped image carrier whose surface moves endlessly while being stretched on a plurality of stretching members. The present invention relates to an image forming apparatus provided with image carrier surface moving means for moving the image carrier surface so as to sequentially face the surface of each latent image carrier of the plurality of image forming means.

[0002]

2. Description of the Related Art In recent years, in color image forming apparatuses such as color copying machines and color printers, there is an increasing demand for high-speed image formation of color images as fast as monochrome images. Therefore, each of the plurality of photoconductors arranged side by side is provided with a developing device individually, a monochromatic toner image is formed on each photoconductor, and the monochromatic toner images are once sequentially transferred to an intermediate transfer belt as an intermediate transfer body. Thereafter, a so-called tandem type image forming apparatus, which collectively transfers a composite color image from the intermediate transfer belt onto a transfer material, is drawing attention.

[0003]

However, in the above-mentioned tandem type image forming apparatus, the peripheral length of the intermediate transfer belt must be at least longer than that of the transfer material, and at least two or more photoconductors and each photoconductor are required. It is difficult to reduce the size of the apparatus because individual developing devices are arranged side by side on the body so as to face the intermediate transfer belt.

[0004] Here, the present applicant has filed Japanese Patent Application No. 2001-12.
No. 5551, a belt-shaped image carrier that moves endlessly while being stretched by a plurality of stretching members, and a portion of the image carrier that is stretched between two of the plurality of stretching members. By pressing from the outer peripheral surface side, the image carrier of the portion is bent toward the inner side of the belt, and at least a part of the cleaning member is housed in the space formed by the bending, thereby reducing the size of the apparatus. Image forming apparatus was proposed. Then, as a result of diligent study by the present inventor, the above-mentioned Japanese Patent Application No. 2001
It was concluded that the size of the image forming apparatus can be further reduced by applying the configuration of the invention proposed in No. 125551 to the tandem type image forming apparatus.

The present invention has been made in view of the above background, and an object of the present invention is to further reduce the size of a so-called tandem type image forming apparatus, and to satisfy the demand for further size reduction. An object of the present invention is to provide an image forming apparatus that can meet the requirements.

[0006]

In order to achieve the above object, the invention of claim 1 provides a latent image carrier for carrying an electrostatic latent image and a surface for charging the latent image carrier. Charging means, latent image forming means for forming an electrostatic latent image on the latent image carrier, developing means for developing the electrostatic latent image into a toner image, and the latent image carrier A plurality of image forming means having a transfer means for transferring the above toner image onto a belt-shaped image carrier whose surface moves endlessly while being stretched on a plurality of stretching members; and An image forming apparatus comprising image carrier surface moving means for moving the image carrier surface so as to sequentially face the surface of each latent image carrier of the plurality of image forming means, wherein an outer peripheral surface of the image carrier is provided. A proximity member arranged close to the outside and a portion stretched between two of the plurality of stretching members And a bending member that presses the image bearing member from the outer peripheral surface side to bend the image bearing member in the portion toward the inner side of the belt, and in a space generated by bending the portion by the bending member, The proximity member is arranged so that at least a part of the proximity member is accommodated.

In this image forming apparatus, a belt-shaped image carrier that is endlessly moved while being stretched by a plurality of stretching members is used.
The belt is bent inward by the bending member. Specifically, the portion of the image carrier that is stretched between two of the plurality of stretching members is bent by the bending member. Then, in the space created by this bending, a proximity member that is arranged close to the outside of the outer peripheral surface of the image carrier is arranged. As a result, in the vicinity of the belt-shaped image bearing member, when the image bearing member is stretched as it is between the two stretching members, that is, as compared with the case where the image bearing member in between is not bent by the bending member, Space saving can be achieved as much as at least part of the proximity member enters the space created by bending. Further, since the space generated by such space saving can be effectively used, the degree of freedom of layout is increased. As a result, it is possible to save the space of the entire device by appropriately setting the layout in the device.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the proximity member is a member that performs a predetermined process on the belt-shaped image carrier. .

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, there is provided secondary transfer means for transferring the toner image on the belt-shaped image carrier to a transfer member, and the proximity member is the The cleaning member is a cleaning member for cleaning the transfer residual toner remaining on the image carrier after the transfer by the secondary transfer means.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, a cleaning bias is applied to the cleaning member, which bias has a reverse polarity to the charging polarity of the toner image before being transferred by the secondary transfer means. It is characterized by having an applying means.

According to a fifth aspect of the present invention, in the image forming apparatus according to the first, second, third or fourth aspect, the charging polarity of the toner image before being transferred to the bending member by the secondary transfer means is the same. It is characterized in that it has a bias applying means for applying a bias.

The invention of claim 6 is the invention of claims 1, 2, 3, 4
Alternatively, in the image forming apparatus of No. 5, at least the outer peripheral surface of the belt-shaped image carrier is made of an elastic member.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a color electrophotographic copying machine (hereinafter referred to as "color copying machine") which is an image forming apparatus will be described below. Figure 1
FIG. 1 is a schematic configuration diagram of a tandem indirect transfer type color copying machine according to the present embodiment. A schematic configuration and an operation of an image forming unit which is a main part of the color copying machine according to the present embodiment will be described with reference to FIG. In addition to the image forming unit shown in FIG. 1, this color copying machine includes a color image reading unit (hereinafter referred to as a color scanner), a paper feeding unit, a control unit, and the like, which are not shown. The image forming unit is of a tandem type in which the photosensitive drums 100, 101, 102 and 103 are continuously arranged in parallel. Photoconductor drum 1
00, 101, 102, 103, photoconductor cleaning devices 300, 301, 302, 303 including charging chargers 200, 201, 202, 203, cleaning blades and fur brushes, respectively, and a writing optical unit and a developing unit (not shown). 400, 40
1, 402, 403, an intermediate transfer unit 500 as an intermediate transfer device, a paper transfer unit 600, a fixing unit 700 using a fixing roller pair 701, and the like.

The photoconductor drums 100, 101, 10
Reference numerals 2 and 103 are rotated counterclockwise by an unillustrated drive motor, and the toner in each developing device is charged to a desired polarity by stirring with the carrier. A developing bias voltage is applied to the developing sleeves (not shown) provided in the developing units 400, 401, 402, 403 by a developing bias power source (not shown), so that the developing sleeves 100, 101, 102, 103.
Is biased to a predetermined potential with respect to the metal base layer.

The intermediate transfer unit 500 includes an intermediate transfer belt 50 as an image carrier which is stretched around a plurality of rollers.
1 and the like, around the intermediate transfer belt 501,
A pre-transfer charger (hereinafter,
A “PTC” 502, a secondary transfer belt 601 as a transfer material carrier of the paper transfer unit 600, a secondary transfer bias roller 605 as a secondary transfer charge applying unit, and the like are arranged.

The intermediate transfer belt 501 includes a plurality of rollers, specifically, a primary transfer bias roller 110 as a primary transfer charge imparting means for each photosensitive drum,
111, 112, 113, a belt driving roller 508, a driven roller 509, a secondary transfer opposing roller 510, a cleaning opposing roller 511, and a belt charge eliminating roller 512 as a pre-primary charge eliminating means. Each roller is made of a conductive material, and the primary transfer bias roller 11
Each roller other than 0, 111, 112, 113 is grounded. Primary transfer bias rollers 110, 111, 11
2, 113, 1 controlled by constant current or constant voltage method
Next transfer power sources 800, 801, 802, 803 apply a transfer bias of a predetermined current or voltage according to the superposition of the toner images. Above PTC502
Is the photoconductor drums 100, 101, 1 at the primary transfer portion.
Before the toner image on the intermediate transfer belt 501 transferred from 02, 103 is transferred to a transfer paper as a transfer material, the toner image is uniformly charged. Further, the intermediate transfer belt 501 is driven in the clockwise direction by an arrow by a belt driving roller 508 which is rotationally driven by a driving motor (not shown).

Now, when making a copy using this color copying machine, an original is set on the color scanner and a start switch (not shown) is pushed. Then, the color scanner reads the original image. When the start switch is pressed, the belt driving roller 508 rotates and the intermediate transfer belt 501 is rotatably conveyed. At the same time, the photosensitive drum 10
0, 101, 102, 103 are rotated to form black, yellow, magenta, and cyan single-color images on the photosensitive drums, respectively. Then, the intermediate transfer belt 501
Along with the conveyance of the above, the single color images are sequentially transferred to form a composite color image on the intermediate transfer belt 501. Then, the secondary transfer belt 601 is rotated in synchronization with the composite color image on the intermediate transfer belt 501, and a transfer paper (not shown) is fed between the intermediate transfer belt 501 and the paper transfer unit 600, and the paper transfer unit 600 is operated. Transfer and record a color image on transfer paper. The transfer sheet after the image transfer is conveyed by the secondary transfer belt 601 and is sent to the fixing unit 700, where heat and pressure are applied by the fixing roller pair 701 to fix the transfer image, and then, a discharge tray (not shown). Discharged on top. On the other hand, the intermediate transfer belt 501 after the image transfer is removed by the intermediate transfer cleaning device 900 to remove the residual toner remaining on the intermediate transfer belt 501 after the image transfer and is ready for the next image formation.

Next, the characteristic structure of this embodiment will be described. FIG. 2 is a schematic configuration diagram showing the belt cleaning device 900 and its peripheral mechanism. The intermediate transfer belt 501 is pressed by the cleaning roller 20 from the surface holding the toner image and bent in the opposite direction, and the transfer cleaning unit 900 is arranged in the space formed by the bending, and the transfer unit configuration is small. It has become.

A scraper blade (not shown) is in contact with the surface of the cleaning roller 20, and the toner transferred to the cleaning roller 20 is scraped off and collected and stored in the apparatus. Therefore, it is desirable that the cleaning roller 20 be coated with Teflon (registered trademark) or the like having a good releasability so that the transferred toner can be scraped off well.

A toner collecting roller 12 is in contact with the fur brush 10, and the transfer residual toner scraped off by the fur brush 10 is electrostatically adsorbed by the biased toner collecting roller 12 and scraped by a scraper blade (not shown). It is dropped and stored in the device. The fur brush 10 and the toner collecting roller are provided on the upstream side of the cleaning roller 20 in the rotation direction of the intermediate transfer belt 501 by the fur brush supporting member 16.

A DC voltage having the same polarity as that of the transfer residual toner is applied to the cleaning roller 20 from a terminal 23 by a bias power source 21. Conductive fur brush 10
A DC voltage having a polarity opposite to the polarity of the transfer residual toner remaining on the intermediate transfer belt 501 due to peeling discharge generated when the transfer paper is separated after the secondary transfer is generated by the bias power supply 11 at the terminal 13.
Is applied via the toner collecting roller 12.

As shown in FIG. 3, the cleaning roller 2
0 is supported at both ends via electrically insulated bearings attached to the pre-transfer cleaning side plate 70 and the post-transfer cleaning side plate 71. A bearing 73 fixed to the transfer cleaning front side plate 70 and a bearing 75 fixed to the transfer cleaning rear side plate 71 are supported by a support shaft 74 fixed to the front and rear side plates of the image forming apparatus main body (not shown). There is. Further, the transfer cleaning pre-side plate 70 has an intermediate transfer belt tension adjusting groove 76, and the pre-transfer cleaning side plate 70 and the post-transfer cleaning side plate 71 are provided with the supporting shaft 74 as a fulcrum.
Is rotated so as to be pressed against the intermediate transfer belt 501, and is fixed to the front side plate of the image forming apparatus main body (not shown) so that the tension of the intermediate transfer belt 501 can be adjusted. The tension can be released by rotating the pre-transfer cleaning side plate 70 and the post-transfer cleaning side plate 71 so that the cleaning roller 20 separates from the intermediate transfer belt 501 with the support shaft 74 as a fulcrum, so that the intermediate transfer belt 501 is subjected to the intermediate transfer. Can be removed from the unit.

The front side plate 70 for transfer cleaning has a fur brush biting amount adjusting groove 17, and when the position of the cleaning roller 20 changes due to the tension of the intermediate transfer belt 501, the fur brush supporting member 16 is tilted to adjust the biting amount of the fur brush. Then, the fur brush can be fixed in the groove 17 for adjusting the bite amount.

After the transfer cleaning of the cleaning roller 20 of FIG. 4, the cleaning roller pulley 5 is provided on the side plate 71 side.
0 is connected. Cleaning roller pulley 50
Is connected via a timing belt 51 to a drive motor (not shown), and is rotationally driven so that the linear velocity on the surface of the intermediate transfer belt 501 and the linear velocity on the surface of the cleaning roller 20 become constant. On the other hand, the timing belt 51 has
The fur brush drive pulley 52 is interposed and is driven to rotate at the same time.

The fur brush driving pulley 52 is driven to rotate by rotating a gear 55 connected to the toner collecting roller 12 and a fur brush gear 54 via an idler gear 53.
The fur brush 10 connected to is rotated in the opposite direction to the toner collecting roller 12. The fur brush 10 rotates in the opposite direction to the running direction of the intermediate transfer belt 501. It is preferable to change the reduction ratio of the cleaning roller pulley 50 and the fur brush drive pulley 52 so that the rotation speed of the fur brush 10 is twice or more the traveling speed of the intermediate transfer belt 501.

The intermediate transfer belt 501 includes a surface layer, an intermediate layer,
The belt material has a multi-layered structure including a base layer.
The outer peripheral surface side, which contacts the photosensitive drum 100 and the like, is a surface layer and an elastic layer. The inner peripheral surface side is a base layer, which is a hard layer that does not expand or contract. Further, an adhesive layer for adhering both layers is interposed between the intermediate layer and the base layer. In this way, since the surface layer of the intermediate transfer belt 501, which is the toner image bearing surface, is an elastic layer, for example, at the transfer nip portion formed between the intermediate transfer belt 501 and the transfer paper conveyed by the secondary transfer belt 601, the intermediate transfer belt is formed. The surface layer of 501 is elastically deformed, and it is possible to prevent a transfer failure due to a step or the like of the toner image.

The photosensitive drums 100, 101, 10
As the photosensitive member constituting 2, 103, a conductive support is heated to 50 ° C. to 400 ° C., and a vacuum deposition method, a sputtering method, an ion plating method, a thermal CVD method, a photo CVD method is applied on the support. Silicon formed by a film forming method such as a plasma CVD method or a plasma CVD method (hereinafter, referred to as “a-S
i ". A-Si having a photoconductive layer composed of
System photoconductors can be used. In particular, plasma CVD
Method, that is, the source gas is decomposed by direct current or high frequency or microwave glow discharge, and aS is deposited on the support.
A photoreceptor having an i-deposited film is suitable. The a-Si-based photoconductor has a high surface hardness and a semiconductor laser (770 to 80).
It exhibits high sensitivity to long-wavelength light (such as 0 nm), and almost no deterioration is observed due to repeated use. For this reason,
It is used as a photoconductor for electrophotography in high-speed copying machines and laser beam printers (LBP).

An example of the layer structure of the a-Si type photoreceptor will be shown below. FIG. 5 is a cross-sectional view when the photoconductor is cut in the layer thickness direction in order to explain four examples of the layer structure of the a-Si-based photoconductor. FIG. 5A shows a photoconductor 150a in which a photoconductive layer 152a made of a-Si: H, X is formed on a support 151a. FIG. 5B shows a photoconductor 150b in which a photoconductive layer 152b made of a-Si: H, X and an a-Si-based surface layer 153b are laminated in this order on a support 151b. ing. Figure 5
(C) is a photoconductive layer 1 made of a-Si based charge injection blocking layer 154c and a-Si: H, X on the support 151c.
52c and a-Si system surface layer 153c show the photoconductor 150c formed by laminating in this order. Figure 5
In (d), a photoconductive layer including a charge transport layer 156d including a-Si: H, X and a charge generating layer 155d is formed on a support 151d, and an a-Si based surface layer is formed thereon. The photoconductor 150d on which 153d is formed is shown.

The support 151 of the photoconductor may be conductive or electrically insulating. As the material of the conductive support 151, Al, Cr, Mo, Au, In, Nb, Te, V,
Metals such as Ti, Pt, Pd, and Fe and alloys thereof such as stainless steel can be used. As the electrically insulating support 151, at least the surface on the side where the photosensitive layer is formed may be subjected to a conductive treatment. As a material of the electrically insulating support 151, synthetic resin such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polystyrene, polyamide, or glass, ceramic or the like can be used. The shape of the support 151 may be cylindrical, plate-shaped, endless belt-shaped, or the like having a smooth or uneven surface, and its thickness is such that a photoreceptor having desired characteristics can be formed. It is set appropriately. When the photoreceptor is required to have flexibility, it is made as thin as possible within a range in which the function as the support 151 can be sufficiently exhibited. However, the support 151 is usually set to 10 μm or more in terms of manufacturing and handling, mechanical strength and the like.

As shown in FIG. 5 (c), the a-Si-based photosensitive member may be provided with a charge from the conductive support side between the conductive support 151c and the photoconductive layer 152c as required. It is desirable to provide a charge injection blocking layer 154c that functions to block the injection. That is, the charge injection blocking layer 154c is
The photosensitive layer has a function of preventing charges from being injected from the side of the support 151c to the side of the photoconductive layer 152c when the free surface is subjected to a charging process of a constant polarity, and is subjected to a charging process of the opposite polarity When it does, such a function is not exhibited, and it has so-called polarity dependence. In order to impart such a function, the charge injection blocking layer 154c contains a larger number of atoms for controlling the conductivity than the photoconductive layer 152c.
The layer thickness of the charge injection blocking layer 154c is 0.1 in view of obtaining desired electrophotographic characteristics and economical effects.
It is preferably -5 μm, more preferably 0.3-4 μm, and most preferably 0.5-3 μm.

The photoconductive layer 152 has photoconductivity,
If necessary, it is formed on the undercoat layer. Photoconductive layer 15
The layer thickness of 2 is appropriately determined in terms of obtaining desired electrophotographic characteristics and economic effects, and is preferably 1 to 100 μm, more preferably 20 to 50 μm, and 23 to 45 μm. It is best to have.

The charge transport layer 156d is the photoconductive layer 15
It is a layer mainly exhibiting the function of transporting charges when the two are functionally separated. The charge transport layer 156d may be formed of a-SiC: H, F, O containing at least a silicon atom, a carbon atom and a fluorine atom, and if necessary, a hydrogen atom and an oxygen atom, as its constituent elements. it can. The charge transport layer 156d is appropriately formed so as to obtain desired photoconductive properties, particularly charge retention properties, charge generation properties, and charge transport properties. In the present embodiment, it is particularly preferable that the oxygen atom is contained. The layer thickness of the charge transport layer 156d is appropriately determined in view of obtaining desired electrophotographic characteristics and economic effects, and is preferably 5 to 50 μm, more preferably 10 to 40 μm, and 20 Optimally, it is ˜30 μm.

The charge generation layer 155d is the photoconductive layer 15
It is a layer mainly exhibiting the function of generating charges when the two are functionally separated. The charge generation layer 155d includes, as a constituent element, at least silicon atoms, substantially no carbon atoms, and if necessary, a hydrogen atom containing a-Si:
It can be formed of H. The charge generation layer 155d is appropriately formed so as to obtain desired photoconductive characteristics, particularly charge generation characteristics and charge transport characteristics. The layer thickness of the charge generation layer 155d is appropriately determined in view of obtaining desired electrophotographic characteristics and economical effects, and is preferably 0.5 to 15 μm, more preferably 1 to 10 μm. ,
The optimum value is 1 to 5 μm.

A surface layer 153 can be further provided on the photoconductive layer 152 formed on the support 151 in the a-Si type photoreceptor, if necessary. This surface layer 153
Is preferably an a-Si system. The surface layer 153 is
It has a free surface, mainly moisture resistance, continuous repeated use characteristics,
It is formed so as to obtain desired characteristics in terms of electrical pressure resistance, use environment characteristics, and durability. The layer thickness of the surface layer 153 is usually 0.01 to 3 μm, preferably 0.05.
˜2 μm, optimally 0.1 to 1 μm. Here, if the layer thickness is less than 0.01 μm, it is likely to be lost during use as a photoreceptor due to wear or the like, and if it exceeds 3 μm, electrophotographic characteristics such as increase in residual potential may occur. Is likely to decrease.

The developer used in this embodiment will be described below. The developer has a weight average diameter of 4 to
15 μm is desirable in terms of improving the resolution of the image. The weight average diameter can be measured by the following procedure. First, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of an electrolytic aqueous solution. here,
The electrolyte is approximately 1% NaCl using first-grade sodium chloride.
An aqueous solution was prepared. Then, 2 to 20 mg of the measurement sample is further added, and the electrolytic solution in which the measurement sample is suspended is
Disperse with an ultrasonic disperser for about 1 to 3 minutes, for example,
The volume and number of toner particles or toner are measured with a 100 μm aperture using a measuring device such as ISOTON-II (manufactured by Coulter). Since the volume distribution and the number distribution can be calculated from the measurement result, the weight average particle diameter and the number average particle diameter of the toner can be obtained from the distribution.

As a channel, 2.00 to 2.52
Less than μm; 2.52 to less than 3.17 μm; 3.17 to
4. 4.0 μm or less; 4.00 to 5.04 μm or less;
04 to less than 6.35 μm; 6.35 to less than 8.00 μm; 8.00 to less than 10.08 μm; 10.08 to 1
Less than 2.70 μm; 12.70 to less than 16.00 μm;
16.00 to less than 20.20 μm; 20.20 to 25.
Less than 40 μm; 25.40 to less than 32.00 μm; 3
13 channels of 2.00 to less than 40.30 μm are used, and particles of 2.00 μm to less than 40.30 μm are targeted.

The developer may be a one-component developer or a two-component developer. Examples of the material forming the toner contained in the developer include a binder resin and a colorant. The proportion of these materials in the entire toner is 75% to 93% of the binder resin, 3% to 10% of the colorant, 3% to 8% of the release agent, and 1% to 7% of the other components. is there.

The binder resin used is, for example, a homopolymer of styrene such as polystyrene, poly-p-chlorostyrene, or polyvinyltoluene or a substitution product thereof; styrene-p-chlorostyrene copolymer, styrene-vinyl. Toluene copolymer, styrene-vinyl naphthalene copolymer, styrene-acrylic acid ester copolymer, styrene-methacrylic acid ester copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, Examples thereof include styrene-vinyl methyl ether copolymer, styrene-vinyl ethyl ether copolymer and styrene-vinyl methyl ketone.

As the colorant, conventionally known inorganic or organic dyes / pigments can be used, and examples thereof include carbon black, aniline black, acetylene black, naphthol yellow, Hansa yellow, Rhodamune lake, and alizarin lake. , Red iron oxide, phthalocyanine blue, and indanthrene blue.

If necessary, a magnetic material can be used as the coloring agent. Examples of magnetic materials include magnetite, γ-iron oxide, ferrite iron, iron oxides such as excess type ferrite; magnetic metals such as iron, cobalt and nickel; iron oxides and magnetic metals, and cobalt, tin, titanium, copper,
Mention may be made of complex metal oxide alloys or mixtures with metals such as lead, zinc, magnesium, manganese, aluminum, silicon. The average particle size of these magnetic particles is preferably in the range of 0.05 to 1.0 μm, more preferably in the range of 0.1 to 0.6 μm, and further preferably in the range of 0.1 to 0.4 μm. It is better to be within the range.
The BET specific surface area of these magnetic particles by the nitrogen adsorption method is preferably in the range of 1 to 20 m ² / g, particularly 2.5.
To 12 m ² / g, and the Mohs hardness is preferably 5 to 7. The shape of the magnetic particles includes octahedron, hexahedron, sphere, needle, and scale, but the octahedron, hexahedron, and sphere having less anisotropy are preferable. When used as a magnetic toner, the magnetic toner particles containing the magnetic material preferably contain 10 to 150 parts by mass, preferably 20 to 120 parts by mass of the magnetic material with respect to 100 parts by mass of the binder resin.

The toner used in this embodiment may contain a small amount of additives within a range that does not have a substantial adverse effect. Examples of the additive include lubricant powders such as Teflon (registered trademark) powder, zinc stearate powder, polyvinylidene fluoride powder; abrasives such as cerium oxide powder, silicon carbide powder, and strontium titanate powder; for example, titanium oxide powder, Flowability-imparting agents or anti-caking agents such as aluminum oxide powders; Conductivity-imparting agents such as carbon black powders, zinc oxide powders, tin oxide powders;
And organic fine particles or inorganic fine particles having opposite polarities.

Further, the toner used in this embodiment includes
A release agent may be added to improve the fixability and the like. Examples of the release agent include paraffin wax and its derivatives, microcrystalline wax and its derivatives, Fischer-Tropsch wax and its derivatives,
Examples thereof include polyolefin wax and its derivative, and carnauba wax and its derivative. The derivative is an oxide,
It includes block copolymers with vinyl monomers and graft modified products of vinyl monomers. In addition, alcohols, fatty acids, acid amides, esters, ketones, hydrogenated castor oil and its derivatives, plant waxes, animal waxes, mineral waxes and petrolactam can also be used.

A charge control agent may be added to the toner used in this embodiment. As the charge control agent for controlling the toner to be negatively charged, for example, an organic metal complex or a chelate compound is effective, and a monoazo metal complex, an acetylacetone metal complex, an aromatic hydroxycarboxylic acid metal complex, an aromatic dicarboxylic acid metal is used. A complex can be mentioned.
Others include aromatic hydroxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, their anhydrides, their esters, and phenol derivatives such as bisphenol. On the other hand, as a charge control agent for controlling the toner to be positively charged, a modified product of nigrosine and a fatty acid metal salt; tributylbenzylammonium-1-hydroxy-4-
Naphtosulfonates, quaternary ammonium salts such as tetrabutylammonium tetrafluoroborate, and onium salts such as phosphonium salts which are analogs thereof and lake pigments thereof, triphenylmethane dyes and lake pigments thereof (lake forming agent). As, phosphotungstic acid, phosphomolybdic acid, phosphotungsten molybdic acid,
Tannic acid, lauric acid, gallic acid, ferricyanide, ferrocyanide). The number average particle size of the fine particle charge control agent is preferably 4 μm or less, and 3
More preferably, it is less than or equal to μm. When these charge control agents are internally added to the toner particles, the toner particles are preferably contained in an amount of 0.1 to 20 relative to 100 parts by mass of the binder resin.
Parts by mass, more preferably 0.2 to 10 parts by mass of the charge control agent are contained.

Further, the toner used in the present embodiment is, if necessary, an additive for a toner which is generally widely used, for example, a fluidizing agent such as colloidal silica, a metal oxide such as titanium oxide or aluminum oxide. The material, abrasives such as silicon carbide, lubricants such as fatty acid metal salts, and the like may be contained. The inorganic fine powder is preferably used in an amount of 0.1 to 2% by weight based on the toner. If it is less than 0.1% by weight, the effect of improving toner aggregation is poor, and if it exceeds 2% by weight, problems such as toner scattering between fine lines, contamination inside the machine, and scratches and abrasion of the photoconductor tend to occur. is there.

As a method of mixing the additive with the toner,
A known method can be used, and mixing can be performed with a device such as a Henschel mixer or a speed kneader. As a method for producing toner powder after kneading and cooling the toner, a conventionally known method may be used, for example, after kneading and cooling,
It is obtained by crushing this with a jet mill and classifying.

The toner for developing an electrostatic charge image produced by such a method can be used as a dry one-component developer and a dry two-component developer. When used as a two-component developer, the mixing ratio of the toner and the carrier is generally about 0.5 to 6.0 parts by weight of the toner per 100 parts by weight of the carrier. When used as a dry two-component developer, the amount of the carrier and the toner of the present invention used is such that the toner particles adhere to the carrier surface of the carrier particles and have a surface area of 3
It is preferable to mix both particles to the extent that they occupy 0 to 90%. As the core particles of the carrier, known particles can be used, and examples thereof include ferromagnetic metals such as iron, cobalt and nickel; alloys and compounds such as magnetite, hematite and ferrite; And the like.

The carrier is for the purpose of increasing durability.
It is preferable to coat the surface with a resin. Examples of the resin forming the coating layer include polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene, and chlorosulfonated polyethylene; polystyrene, acrylic (for example, polymethylmethacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, Polyvinyl and polyvinylidene resins such as polyvinyl chloride, polyvinylcarbazole, polyvinyl ether, and polybiliketone; vinyl chloride-vinyl acetate copolymers; silicone resins composed of organosiloxane bonds or modified products thereof (for example, alkyd resins, polyester resins, epoxy resins). , Modified products such as polyurethane); polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroe Polyamides; polyesters; fluoroplastic Len and polyurethane; polycarbonates; - urea amino resins such as formaldehyde resins, epoxy resins and the like. Of these, silicone resins or modified products thereof, and fluororesins, particularly silicone resins or modified products thereof, are preferable from the viewpoint of preventing toner spent.

As for the method of forming the coating layer, the coating liquid for forming the coating layer may be applied to the surface of the carrier core particles by a spraying method, a dipping method or the like as in the conventional method. The thickness of the coating layer is 0.1-2
0 μm is preferable.

An example of a method for producing a two-component developer as the developer will be described below. A mixture having the composition shown below was melt-kneaded, and then pulverized and classified. Polyester resin (weight average particle size: 300 μm, softening temperature: 80.2 ° C.) 100 parts by weight carbon black 10 parts by weight Polypropylene (weight average particle size: 180 μm) 5 parts by weight Quaternary ammonium salt 2 parts by weight

Further, 0.3 part by weight of hydrophobic silica was mixed with 100 parts by weight of the base colored particles to give an average particle size of 9.
A toner of 0 μm was obtained. Further, 2 parts by weight of polyvinyl alcohol and 60 parts by weight of water were put into a ball mill and mixed for 12 hours with respect to 100 parts by weight of magnetite prepared by a wet method to prepare a magnetite slurry. This slurry was spray-granulated with a spray dryer to give spherical particles. The particles were fired in a nitrogen atmosphere at a temperature of 1000 ° C. for 3 hours and then cooled to obtain core particles 1.

Next, the following mixture was dispersed with a homomixer for 20 minutes to prepare a coating layer forming liquid. Silicone resin solution 100 parts by weight Toluene 100 parts by weight γ-aminopropyltrimethoxysilane 15 parts by weight Carbon black 20 parts by weight

Using the fluidized bed coating apparatus, 1000 parts by weight of core particles were coated with this coating layer forming liquid to obtain a silicone resin coated carrier. Then, with respect to 97.5 parts by weight of this carrier, toner 2.
A two-component developer was prepared by mixing 5 parts by weight.

In this embodiment, the case where the intermediate transfer belt 11 is bent by the bending roller 11 has been described, but a photosensitive belt or the like may be used.

As described above, according to this embodiment, the photosensitive drum as the latent image carrier for carrying the electrostatic latent image and the charging as the charging means for charging the photosensitive drum. A charger, a writing optical unit as a latent image forming means for forming an electrostatic latent image on the photosensitive drum, and a developing unit as a developing means for developing the electrostatic latent image into a toner image. And an intermediate transfer belt as a belt-shaped image carrier whose surface moves endlessly in a state where the toner image on the photosensitive drum is stretched around a plurality of stretching members such as a belt driving roller and a driven roller. A plurality of image forming means having a primary transfer bias roller as a transfer means for transferring to the intermediate transfer means, and the intermediate transfer so as to sequentially face the surface of each photoconductor drum of the plurality of image forming means. Be In the image forming apparatus having a belt driving roller as an image bearing member surface moving means for moving the door surface, and the transfer cleaning section as a proximity member that is arranged close to the outer circumferential surface outside of the intermediate transfer belt,
A bending member that presses the portion of the intermediate transfer belt that is stretched between two of the plurality of belt driving rollers and driven rollers from the outer peripheral surface side and bends the portion of the intermediate transfer belt in the belt inward direction. And the transfer cleaning section is arranged such that at least a part of the transfer cleaning section is housed in a space generated by bending the section by the cleaning roller. In this image forming apparatus, the intermediate transfer belt, which moves endlessly while being stretched around a plurality of stretching members such as belt driving rollers and driven rollers, is bent inward by the cleaning roller. Specifically, the portion of the intermediate transfer belt stretched between two of the plurality of stretching members is bent by the cleaning roller. Then, in the space created by this bending, a transfer cleaning section is arranged in proximity to the outside of the outer peripheral surface of the intermediate transfer belt. As a result, around the intermediate transfer belt,
Compared to when the intermediate transfer belt is stretched between the two stretching members as it is, that is, when the intermediate transfer belt between them is not bent by the cleaning roller, at least a part of the transfer cleaning portion is formed by bending. Space can be saved as much as it enters.
Further, since the space generated by such space saving can be effectively used, the degree of freedom of layout is increased. As a result, by appropriately setting the layout in the apparatus, it is possible to save the space of the so-called tandem type image forming apparatus, which tends to be large in size. Further, in the image forming apparatus, the proximity member is a member that performs a predetermined process on the intermediate transfer belt as the belt-shaped image carrier. In this image forming apparatus, at least a part of a member that performs a predetermined process on the intermediate transfer belt is arranged so as to be accommodated in a space formed by bending. Taking a cleaning device for cleaning the intermediate transfer belt as an example, a cleaning member such as a cleaning blade or a cleaning roller corresponds to this member. Here, for example, when the cleaning member is arranged in the same arrangement as the conventional one and only the toner tray for receiving the toner collected by the cleaning member is accommodated in the space formed by the bending, the space saving is efficient. Cannot be realized. Therefore, in this image forming apparatus, a member that performs a predetermined process on the intermediate transfer belt is a proximity member, and at least a part of the member is arranged to be accommodated in a space formed by bending. This makes it possible to efficiently save space. The image forming apparatus further includes a paper transfer unit as a secondary transfer unit that transfers the toner image on the intermediate transfer belt as the belt-shaped image carrier onto a transfer paper as a transfer member, and the proximity member. Is a fur brush as a cleaning member for cleaning the transfer residual toner remaining on the intermediate transfer belt after the transfer by the paper transfer unit. As a cleaning member for cleaning the transfer residual toner on the intermediate transfer belt, a blade cleaning method using a cleaning blade can be considered. However, in this blade cleaning method, if a small particle size toner is used or a polymerized toner in which particles are uniformly spherical is used for higher image quality, the attraction force between the transfer residual toner and the intermediate transfer belt is strong. However, it is difficult to scrape off with a cleaning blade, resulting in poor cleaning. Also, for example, when using an elastic material for the intermediate transfer belt, the friction between the intermediate transfer belt and the cleaning blade increases and the cleaning blade squeals,
There is a problem of getting involved. In order to solve these problems, there is a brush cleaning system that uses a fur brush as a cleaning member. However, the brush cleaning method using the fur brush occupies a wide area in the apparatus because the cleaning apparatus becomes large and the degree of freedom of layout is limited. Therefore, the image forming apparatus is arranged so that at least a part of the fur brush is housed in the space formed by bending. As a result, the degree of freedom in the storage arrangement of the cleaning device, which is difficult to miniaturize, increases, so that efficient space saving can be achieved. In the image forming apparatus,
For the fur brush as the cleaning member, the above 2
It has a bias power source as a cleaning bias applying means for applying a bias having a polarity opposite to the charging polarity of the toner image before being transferred by the paper transfer unit as the next transfer means. In this image forming apparatus, a bias power source applies a bias having a polarity opposite to the charging polarity of the toner image before being transferred by the paper transfer unit to the fur brush. Accordingly, when the transfer residual toner on the intermediate transfer belt is collected by the fur brush, the transfer residual toner can be electrostatically adsorbed to the fur brush and collected. Therefore, the cleaning performance by electrostatic attraction can be added to the cleaning performance of the fur brush itself. In the image forming apparatus, as a bias applying unit that applies a bias having the same polarity as the charging polarity of the toner image before being transferred by the paper transfer unit as the secondary transfer unit to the cleaning roller as the bending member. Has a bias power supply. In this image forming apparatus, a bias power source applies a bias having the same polarity as the charging polarity of the toner image before being transferred by the paper transfer unit to the cleaning roller.
The charge polarity of the transfer residual toner on the intermediate transfer belt may change to the opposite polarity due to peeling discharge that occurs when the transfer paper is separated from the intermediate transfer belt after the transfer by the paper transfer unit. The bias applied to the fur brush is
Since it has the same polarity as the transfer residual toner of the opposite polarity, it becomes difficult to electrostatically adsorb it to the fur brush and collect it. In this image forming apparatus, a bias having the same polarity as the charging polarity of the toner image before being transferred by the paper transfer unit, that is, a bias having the opposite polarity to the transfer residual toner having the opposite polarity is applied to the cleaning roller. The transfer residual toner can be electrostatically adsorbed to the cleaning roller and collected.
Further, since the transfer residual toner having the opposite polarity has the same polarity as the polarity applied to the fur brush, it may repel and scatter from the intermediate transfer belt. It can also be prevented. That is, the cleaning roller as the bending member in the image forming apparatus also functions as the cleaning member. In the image forming apparatus,
At least the outer peripheral surface of the intermediate transfer belt as the belt-shaped image bearing member is made of an elastic member. In this image forming apparatus, the toner image bearing surface of the intermediate transfer belt,
For example, since the outer peripheral surface of the intermediate transfer belt is elastically deformed at the transfer nip portion formed between the transfer sheet and the transfer sheet conveyed by the secondary transfer belt, it is possible to prevent a transfer failure due to a step of the toner image or the like. it can.

[0055]

According to the first aspect of the invention, the belt-shaped image carrier is bent to save space, and at least a part of the proximity member is housed in the space created by the bending. Further space saving can be achieved,
The degree of freedom in layout increases. As a result, there is an effect that it is possible to save the space of the so-called tandem type image forming apparatus and to achieve miniaturization.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a main part of a tandem type color copying machine according to an embodiment.

FIG. 2 is an enlarged view of the vicinity of an intermediate transfer cleaning device.

FIG. 3 is a perspective view of the vicinity of an intermediate transfer cleaning device.

FIG. 4 is a view in the vicinity of the intermediate transfer cleaning device, and FIG.
The perspective view seen from the back side in the figure.

5A to 5D are cross-sectional views of the photoconductor when cut in the layer thickness direction in order to explain four examples of the layer structure of the a-Si-based photoconductor.

[Explanation of symbols]

10 Fur Brushes 11, 21 Bias Power Supply 20 Cleaning Rollers 100, 101, 102, 103 Photosensitive Drums 200, 201, 202, 203 Charging Chargers 300, 301, 302, 303 Photosensitive Cleaning Devices 400, 401, 402, 403 Developing Units 500 Intermediate Transfer Unit 501 Intermediate Transfer Belt 510 Secondary Transfer Opposing Roller 600 Paper Transfer Unit 601 Secondary Transfer Belt 605 Secondary Transfer Bias Roller 804 Secondary Transfer Power Supply 900 Intermediate Transfer Cleaning Device

Claims (6)

[Claims] 1. A latent image carrier for carrying an electrostatic latent image,
Charging means for charging the surface of the latent image carrier, latent image forming means for forming an electrostatic latent image on the latent image carrier, and developing the electrostatic latent image into a toner image. And a transfer means for transferring the toner image on the latent image carrier onto a belt-shaped image carrier whose surface moves endlessly while being stretched by a plurality of stretching members. An image including a plurality of image forming means having the image forming means, and an image carrier surface moving means for moving the surface of the image carrier so as to sequentially face the surface of each latent image carrier of the plurality of image forming means. In the forming apparatus, the proximity member arranged close to the outside of the outer peripheral surface of the image carrier and the part of the image carrier that is stretched between two of the plurality of stretching members are And a bending member that presses from the side to bend the image carrier of the portion toward the inner side of the belt, The space formed by bending the partial by song member, such that at least a portion of the proximity member is housed, an image forming apparatus characterized in that a said proximity member. 2. The image forming apparatus according to claim 1, wherein the proximity member is a member that performs a predetermined process on the belt-shaped image carrier. 3. The image forming apparatus according to claim 2, wherein the toner image on the belt-shaped image carrier is transferred to a transfer member.
An image forming apparatus having a secondary transfer unit, wherein the proximity member is a cleaning member for cleaning transfer residual toner remaining on the image carrier after the transfer by the secondary transfer unit. 4. The image forming apparatus according to claim 3, wherein the cleaning member has a cleaning bias applying means for applying a bias having a polarity opposite to a charging polarity of the toner image before being transferred by the secondary transfer means. An image forming apparatus characterized by. 5. The image forming apparatus according to claim 1, 2, 3 or 4, wherein a bias having the same polarity as the charging polarity of the toner image before being transferred by the secondary transfer means is applied to the bending member. An image forming apparatus having an applying unit. 6. The image forming apparatus according to claim 1, 2, 3, 4 or 5, wherein at least the outer peripheral surface of the belt-shaped image carrier is made of an elastic member.