JP2002258579A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which forms an overlapped color toner image with large layer thickness, has improved transferability, an intermediate transfer body driving method for preventing driving irregularity of the intermediate transfer body and in which heating of a process member such as an image forming body due to heat from a transfer/fixing part in the image forming apparatus is prevented. SOLUTION: The image forming apparatus is characterized in that a nip part is formed by the intermediate transfer body as a belt member having adherence and the image forming body, transfer bias is impressed on the intermediate transfer body by setting volume resistivity of the intermediate transfer body to be 10<8> to 10<12> Ω.cm, the image forming body is driven by adhesion and electrostatic force to be added to the nip part and a toner image is transferred to the intermediate transfer body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copying machine, a printer, a facsimile, etc., in which charging means, image exposing means, developing means, etc. are arranged around a plurality of image forming bodies, and A toner image is formed, the toner image is superimposed on the adhesive intermediate transfer body, and a superimposed color toner image is formed on the adhesive intermediate transfer body. The present invention relates to an image forming apparatus for transferring and fixing a transfer material.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a multi-color image, an image forming body of the same number as that of a required image and a charging means, an image exposing means and a developing means are provided around the image forming body. , The monochrome toner image formed on each image forming body,
An apparatus for superimposing a color image on an intermediate transfer member,
An apparatus that forms a color image superimposed on an image forming body by repeating charging, image exposure and development for each color by rotating one image forming body a plurality of times, and charging, image exposing and developing on one image forming body There is known an apparatus which transfers a toner image formed by an image forming method onto an intermediate transfer member, repeats the process for each color, and forms a color image superimposed on the intermediate transfer member.

[0003] In particular, an image forming body of the same number as that of a required color and an image forming process means such as a charging means, an image exposing means and a developing means are provided around the image forming body. A color image forming apparatus that forms a color image by superimposing a single-color toner image on an intermediate transfer member has recently been used as a device that forms a high-quality color image.

[0004]

SUMMARY OF THE INVENTION However,
In an image forming apparatus that forms a superimposed color toner image on an intermediate transfer member by a plurality of image forming process units including a charging unit, an image exposing unit, a developing unit, etc. Tends to be defective. Further, when the respective image carriers and the intermediate transfer member are independently driven, there arises a problem that image unevenness due to drive unevenness (image unevenness due to poor registration) occurs. Further, there is a problem that it is difficult for the intermediate transfer member to slide with the image forming member. Further, a process member such as an image forming body is heated by the heat from the transfer / fixing section of the intermediate transfer body, which causes a problem that the image forming body is deteriorated.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems and, in an image forming apparatus for forming a superposed color toner image having a large layer thickness, improves the transferability, and provides an intermediate transfer member which does not cause driving unevenness in an intermediate transfer member. It is an object of the present invention to provide an image forming apparatus having a method for driving a transfer body, and to provide an image forming apparatus that prevents a process member such as an image forming body from being heated by heat from a transfer / fixing unit.

[0006]

An object of the present invention is to transfer a toner image formed on a plurality of image forming bodies, superimpose the toner image on an intermediate transfer body, and place the toner image on the intermediate transfer body. An image forming apparatus for transferring and fixing the superimposed color toner image on a transfer material after forming the superimposed color toner image, wherein the intermediate transfer body is formed into a nip portion with the image forming body as an adhesive belt member. to form a, the volume resistivity of the intermediate transfer body 10 ⁸ ~10 ¹² Ω ·
cm, applying a transfer bias to the intermediate transfer body, driving the image forming body by the adhesive force and the electrostatic force applied to the nip portion, and transferring the toner image to the intermediate transfer body. This is achieved by an image forming apparatus characterized by the following.

[0007]

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 image forming apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional configuration diagram of a color image forming apparatus showing an embodiment of an image forming apparatus according to the present invention, and FIG. 2 is a diagram showing a transfer state of a toner image from an image forming body to an intermediate transfer body. FIG. 3 is a diagram showing a transfer state of a color toner image from an intermediate transfer body to a transfer material.

According to FIGS. 1 to 3, as shown in FIG. 1, the image forming apparatus of the present invention comprises an image reading section A, an image processing section B, an image forming section E and the like.

At the top of the image forming apparatus, there is provided a document table made of a transparent glass plate or the like, and a document placing section 111 composed of a document cover for covering the document D placed on the document table. Below and in the apparatus main body, there is provided an image reading unit A including a first mirror unit 112, a second mirror unit 113, a main lens 120, a color CCD 123, and the like. The first mirror unit 112 includes an exposure lamp 114 and a first mirror 115. The first mirror unit 112 is mounted in parallel with the document table and linearly movable in the horizontal direction of the drawing, and optically scans the entire surface of the document D. The second mirror unit 113 includes a second mirror 116 and a third mirror 117.
And the first so as to always maintain a predetermined optical path length.
It moves linearly in the same direction on both sides at half the speed of the mirror unit 112. Of course, the movement of the second mirror unit 113 is parallel to the platen similarly to the first mirror unit 112. The image of the document D on the document table illuminated by the exposure lamp 114 is
An image is formed on the color CCD 123 via the mirror 115, the second mirror 116, and the third mirror 117. When scanning is completed, the first mirror unit 112 and the second
The mirror unit 113 returns to the original position and waits for the next copy.

Image data of each color obtained by the color CCD 123 is subjected to image processing in an image processing section B, and laser writing is performed in an image forming section E described below as an image signal.

The image forming apparatus shown in FIG. 1 is a tandem-type color image forming apparatus using an intermediate transfer member composed of an adhesive belt member as an image forming portion E. A black (K), cyan (C), magenta (M), and yellow (Y) 4 are formed on the periphery of the adhesive transfer belt 14a as a transfer member.
Process unit 1 as a set of image forming process means
In each process unit 100, K, C, M, and Y toner images are formed on the photosensitive drum 10, and the toner images are superimposedly transferred on the adhesive transfer belt 14a and transferred. The transferred color toner images are collectively transferred and fixed onto recording paper P as a transfer material, and are discharged outside the apparatus.

Since all four process units 100 have a common structure, only one of them will be described.

The photosensitive drum 10 serving as an image forming body is formed by forming a conductive layer and a photoconductive layer of an organic photosensitive layer (OPC) on the outer periphery of a cylindrical substrate. It is driven by the belt 14a and rotated counterclockwise as indicated by the arrow with the conductive layer grounded.

Numeral 11 denotes a scorotron charger as charging means, which is attached to the photosensitive drum 10 in a direction perpendicular to the moving direction of the photosensitive drum 10 so as to face and be close to the photosensitive drum 10.
The photosensitive drum 1 is driven by corona discharge having the same polarity as the toner.
A uniform potential is given to 0.

Reference numeral 12 denotes an exposure optical system as image exposure means for performing K, C, M, and Y image exposure based on image data of an image portion (image forming portion). This is a scanning optical system that performs scanning in parallel with the rotation axis. A latent image is formed by performing image exposure on the uniformly charged photoconductor drum 10 by the exposure optical system 12.

A developing device 13 containing a one-component developer composed of only negatively charged toner or a two-component developer composed of toner and carrier is provided on the periphery of the photosensitive drum 10 to hold the developer. The latent image on the photosensitive drum 10 is reversibly developed in a contact or non-contact manner by a developing roller 13a as a developer transporter that rotates.

Between the developing roller 13a and the photosensitive drum 10, a DC voltage V _DC or a DC voltage V _DC or an AC voltage V _DC is applied.
A developing bias voltage with _AC superimposed is applied. Since charging of the toner is a DC voltage V _DC of the same polarity (negative), do not adhere to the high V _H portion of the absolute value of the potential from the DC voltage V _DC,
The toner amount corresponding to the potential difference adheres to the portion of _VL where the absolute value of the potential is low, and the image is visualized (reversal development).

As a carrier used for the developer, a magnetic carrier having a ferrite core as a core and an insulating resin coated around the core is used. As a toner, a polymerized toner described below is used. In the case of a two-component developer, Is
A mixture of a magnetic carrier and a polymerized toner so as to have a toner concentration of 5 to 10% by mass. The polymerized toner or the polymerized toner and the magnetic carrier are used as a developer.
The developer is regulated to a layer thickness of 0.1 to 0.6 mm on 3a, and is conveyed to the development area.

The polymerized toner used in the image forming apparatus of the present invention has a number average molecular weight of 1 produced by a suspension polymerization method or an emulsion polymerization method.
Secondary particles are prepared by salting out / fusing resin particles having a secondary particle diameter of 10 to 500 nm, and then polymerizing by adding an organic solvent, a coagulant, a polymerization catalyst, and the like, and the polymerization rate has advanced to 80%. The spherical secondary particles (spherical toner) in the solution can be produced by further adding a polymerization catalyst to complete the polymerization.

The salting-out / fusing means that the resin fine particles produced in the polymerization step are salted out with an aggregating agent, excess dispersants, surfactants, etc. are removed, and the size of the resin particles is reduced by heat-sealing. Adjusting.

The number average primary particles are a light scattering electrophoresis particle size analyzer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.).
Can be measured.

The volume average particle size is determined by Coulter Counter TA
-2 or Coulter Multisizer (manufactured by Coulter Inc.).

The salting-out / fusion is carried out by mixing the resin particles with a dispersion liquid such as a release agent or a colorant necessary for forming the toner, or by using a toner composition such as a release agent or a colorant in a monomer. Number average primary particle size 1 prepared by a method such as emulsion polymerization after dispersing the components
It can be carried out by salting out / fusing resin particles of 0 to 500 nm.

That is, a coloring agent and, if necessary, various constituent materials such as a release agent, a charge control agent, and a polymerization initiator are added to the polymerizable monomer, and a homogenizer, a sand mill, a sand grinder, and an ultrasonic disperser are used. Various constituent materials are dissolved or dispersed in the polymerizable monomer by a machine or the like. The liquid in which the various constituent materials are dissolved or dispersed is dispersed in an oil medium having a desired size as a toner in an aqueous medium containing a dispersion stabilizer using a homomixer or a homogenizer. afterwards,
The mixture is transferred to a reactor equipped with a stirring mechanism having stirring blades, and heated so that the polymerization reaction proceeds up to 80% to form spherical particles (spherical toner). Further, a polymerization catalyst is added to proceed with the polymerization to complete the polymerization. After completion of the polymerization, the dispersion stabilizer is removed, filtered, washed, and dried to prepare a polymerized toner used in the image forming apparatus of the present invention.

Examples of the polymerizable monomer constituting the resin as a binder include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene and p-chlorostyrene. , 3,4-dichlorostyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene,
Styrenes such as p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, styrene derivatives, methacrylic acid Methyl, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, Methacrylate derivatives such as diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate,
Acrylate derivative such as isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, phenyl acrylate, etc .; olefins such as ethylene, propylene, isobutylene, vinyl chloride, vinylidene chloride Vinyl halides such as vinyl bromide, vinyl fluoride, vinylidene fluoride, vinyl esters such as vinyl propionate, vinyl acetate and vinyl benzoate; vinyl ethers such as vinyl methyl ether and vinyl ethyl ether; vinyl methyl ketone , Vinyl ethyl ketone, vinyl hexyl ketone, and other vinyl ketones, N-vinyl carbazole, N-vinyl indole, N-vinyl pyrrolidone, and other N-vinyl compounds, vinyl naphthalene, vinyl pyridine, and other vinyl compounds Acrylonitrile, methacrylonitrile, acrylic acid or methacrylic acid derivatives of acrylamide. Among them, vinyl monomers can be used alone or in combination.

It is more preferable to use a polymerizable monomer constituting the resin in combination with one having an ionic dissociation group. For example, those having a substituent such as a carboxyl group, a sulfonic acid group, and a phosphate group as a constituent group of the monomer, specifically, acrylic acid, methacrylic acid,
Maleic acid, itaconic acid, cinnamic acid, fumaric acid, monoalkyl maleate, monoalkyl itaconate, styrenesulfonic acid, allylsulfosuccinic acid, 2-acrylamido-2-methylpropanesulfonic acid, acid phosphooxyethyl Methacrylate,
3-chloro-2-acid phosphooxypropyl methacrylate and the like.

Further, divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol diacrylate, diethylene glycol dimethacrylate, diethylene glycol diacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, neopentyl glycol dimethacrylate,
Polyfunctional vinyls such as neopentyl glycol diacrylate can be used to form a crosslinked resin.

These polymerizable monomers can be polymerized using a radical polymerization initiator. In this case, an oil-soluble polymerization initiator can be used in the suspension polymerization method. As the oil-soluble polymerization initiator, 2,2'-azobis- (2,2
4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis-4-
Azo or diazo polymerization initiators such as methoxy-2,4-dimethylvaleronitrile and azobisisobutyronitrile, benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide , Di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-
Examples include peroxide-based polymerization initiators such as (4,4-t-butylperoxycyclohexyl) propane and tris- (t-butylperoxy) triazine, and polymer initiators having a peroxide in a side chain. .

When an emulsion polymerization method is used, a water-soluble radical polymerization initiator can be used. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and salts thereof, and hydrogen peroxide.

Examples of the dispersion stabilizer include tricalcium phosphate, magnesium phosphate, zinc phosphate, aluminum phosphate, calcium carbonate, magnesium carbonate, calcium hydroxide, magnesium hydroxide, aluminum hydroxide, calcium metasilicate, and calcium sulfate. , Barium sulfate,
Bentonite, silica, alumina and the like can be mentioned. Further, those generally used as surfactants such as polyvinyl alcohol, gelatin, methyl cellulose, sodium dodecylbenzenesulfonate, ethylene oxide adduct, and higher alcohol sodium sulfate can be used as the dispersion stabilizer.

The polymerized toner used in the image forming apparatus of the present invention contains at least a resin and a colorant, but may contain, if necessary, a releasing agent or a charge control agent as a fixability improving agent. You can also. Further, an external additive composed of inorganic fine particles, organic fine particles and the like may be added to particles of the polymerized toner mainly composed of the resin and the colorant.

As the colorant used in the polymerized toner used in the image forming apparatus of the present invention, any of carbon black, dye, pigment and the like can be used.

As carbon black, channel black, furnace black, acetylene black, thermal black, lamp black and the like can be used.

As the dye, C.I. I. Solvent Red 1, 49, 52, 58, 63, 111, 1
22, C.I. I. Solvent Yellow 19, 44, 7
7, 79, 81, 82, 93, 98, 10
3, 104, 112, 162, C.I. I. Solvent Blue 25, 36, 60, 70, 93, 9
5 and the like, and a mixture thereof can also be used. Examples of the pigment include C.I. I. Pigment Red 5, 48: 1, 53: 1, 57: 1, 122,
139, 144, 149, 166, 177,
178, 222, C.I. I. Pigment Orange 3
1, 43, C.I. I. Pigment Yellow 14, 1
7, 93, 94, 138, C.I. I. Pigment Green 7, C.I. I. Pigment Blue 15: 3, 60
Etc. can be used. The above dyes and pigments can be used alone or as a mixture. Although the number average primary particle size of the colorant varies depending on the type, it is generally 10 to 200 nm.
Is preferred.

As a method of adding the colorant, a method of adding the colorant at the stage of polymerizing the monomer and polymerizing it into colored particles can be used. When the colorant is added at the stage of preparing the polymer, it is preferable to use the colorant after treating the surface with a coupling agent or the like so as not to inhibit the radical polymerizability.

Further, low molecular weight polypropylene (number average molecular weight = 1500 to 9000) or low molecular weight polyethylene as a fixing property improving agent may be added.

The charge control agents are also various known ones.
In addition, those that can be dispersed in water can be used. Specifically, nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines,
Quaternary ammonium salt compounds, azo-based metal complexes, salicylic acid metal salts or metal complexes thereof.

The particles of the charge control agent and the fixability improving agent have a number average primary particle diameter of 10 to 500 in a dispersed state.
It is preferable to set it to about nm.

Further, in the polymerized toner used in the image forming apparatus of the present invention, the effect can be more exerted by adding and using fine particles such as inorganic fine particles and organic fine particles as an external additive. It is presumed that the reason for this is that since the burying and desorption of the external additive can be effectively suppressed, the effect is remarkable.

As the inorganic fine particles, inorganic oxide particles such as silica, titania and alumina are preferably used.
Further, it is preferable that these inorganic fine particles have been subjected to a hydrophobic treatment with a silane coupling agent, a titanium coupling agent, or the like.

The polymerized toner formed as described above is
Good charge controllability and good transferability.

An adhesive transfer belt 14a, which is an intermediate transfer member made of an adhesive belt member, in which black (K), cyan (C), magenta (M), and yellow (Y) process units 100 face in parallel. is the volume resistivity of 10 ⁸ ~10 ¹² Ω · cm, a surface resistivity of 10 ⁸ to 10 ¹² Omega
/ □ endless belt, for example, a conductive material dispersed in engineering plastic such as modified polyimide, thermoset polyimide, ethylene tetrafluoroethylene copolymer, polyvinylidene fluoride, nylon alloy, etc., having a thickness of 1
This is a seamless belt in which an adhesive layer is coated with a silicone rubber or urethane rubber having a thickness of about 50 to 150 μm on the outside of a resin film substrate having a layer thickness of about 00 to 300 μm. The adhesive transfer belt 14a is stretched around and circumscribes a transfer / fixing roller 14f, a driven roller 14e, and a tension roller 14k, which also serves as a drive. The fixing roller 14f is rotated in the direction indicated by the arrow in the figure. At the transfer position for each color where the primary transfer roller 14c is provided, the pressure of the adhesive transfer belt 14a is set between the adhesive transfer belt 14a and the photosensitive drum 10 by the pressing of the pressing rollers ROa provided at both ends of the transfer position inside the adhesive transfer belt 14a. A nip portion Nc is formed, and the photosensitive drum 10 is driven to rotate by the adhesive force of the adhesive transfer belt 14a and the electrostatic force of the transfer bias VTa applied to the primary transfer roller 14c. The transfer / fixing roller 14f is formed by providing a rubber roller layer (not given) on the outer peripheral surface of a metal pipe (not given), and a halogen lamp HLa as a heating means is provided inside the transfer / fixing roller 14f. And
The transfer / fixing roller 14f is heated.

The primary transfer roller 14c, which is a roller member for transferring a toner image on the image forming body for each color, is connected to the photosensitive drum 10 for each color with the adhesive transfer belt 14a interposed therebetween.
And a transfer area (no symbol) for each color formed of the nip portion Nc between the adhesive transfer belt 14a and the photosensitive drum 10 for each color. A transfer bias VTa composed of a DC voltage of the opposite polarity (positive polarity in this embodiment) to the toner is applied to the primary transfer roller 14c for each color.
(Primary transfer bias) is applied to the adhesive transfer belt 14a.
The toner image on the photosensitive drum 10 for each color is transferred onto the adhesive transfer belt 14a by the adhesive force of the transfer bias VTa and the electrostatic force of the transfer bias VTa.

At the start of image recording, the adhesive transfer belt 14a is driven and rotated by the start of an intermediate transfer member drive motor (not shown), and receives the drive rotation of the adhesive transfer belt 14a to reduce the adhesive force of the adhesive transfer belt 14a and 1 Due to the electrostatic force of the transfer bias VTa applied to the next transfer roller 14c, the photosensitive drum 10 is closely adhered to the adhesive transfer belt 14a and is driven to rotate, so that the black (K) process unit 1 is rotated.
00 is rotated in the direction indicated by the arrow in the figure. At the same time, application of a potential to the K photoconductor drum 10 is started by the charging action of the K scorotron charger 11.

After a potential is applied to the K photosensitive drum 10, image writing by an electric signal corresponding to the K image data is started by the K exposure optical system 12, and the surface of the K photosensitive drum 10 is written. An electrostatic latent image corresponding to the K image of the original image is formed.

The K latent image is subjected to reversal development in a contact or non-contact state by a K developing unit 13, and a toner image is formed by K toner in accordance with the rotation of the K photosensitive drum 10.

The K toner image formed on the K photoreceptor drum 10 serving as an image forming body by the above-described image forming process is converted into a primary image of K in the K transfer area (no symbol) formed by the nip portion Nc. The image is transferred onto the adhesive transfer belt 14a by the transfer roller 14c.

Next, the adhesive transfer belt 14a is synchronized with the K toner image, and the C toner corresponding to the C image data formed on the C photosensitive drum 10 by the cyan (C) process unit 100. An image is formed by being superimposed on the K toner image by the C primary transfer roller 14c in the C transfer area (no symbol) formed by the nip portion Nc.

By the same process, the image is synchronized with the superposed toner images of K and C, and corresponds to the image data of M formed on the photosensitive drum 10 of M by the process unit 100 of magenta (M). When the M toner image is transferred to the M transfer area (not shown) including the nip portion Nc,
Are formed on the K and C toner images so as to overlap each other.

Further, synchronization with the K, C, and M superposed toner images is established, and the yellow (Y) process unit 100
The Y toner image corresponding to the Y image data formed on the Y photoreceptor drum 10 by the Y primary transfer roller 14c in the Y transfer area (no symbol) formed by the nip portion Nc. K, C, and M toner images are formed on top of each other on the adhesive transfer belt 14a.
A superposed color toner image of M and Y is formed.

The untransferred toner remaining on the peripheral surface of the photosensitive drum 10 for each color after the transfer is cleaned by a photosensitive member cleaning device 19 as an image forming member cleaning unit for each color.

The transfer / fixing roller 14f incorporating a halogen lamp HLa as a heating means is provided on the adhesive transfer belt 1
It is in pressure contact with the heating roller 17 having a built-in halogen lamp HLb as heating means via 4a. The heating roller 17 is formed as a soft roller in which a rubber roller layer (without a sign) having a low rubber hardness is provided on the outer peripheral surface of a metal pipe (without a sign), and the internal halogen lamp HLb is provided.
As a result, the heating roller 17 is heated.

Paper cassette 15 as transfer material storage means
Is supplied by the timing roller 16 in synchronization with the color toner image on the adhesive transfer belt 14a, and the transfer / fixing position (where the transfer / fixing roller 14f and the heating roller 17 face each other) In the transfer / fixing section, no symbol), the color toner image on the adhesive transfer belt 14a is transferred / fixed onto the recording paper P. In the transfer / fixing section, the temperature of the roller is set so that the viscosity of the toner on the adhesive transfer belt 14a is in a rubbery region.
Thereby, fusion of the toner to the recording paper P occurs, and good transfer and fixing are simultaneously performed. The heating roller 17 transfers
It is preferable that the temperature is maintained at substantially the same as that of the fixing roller 14f. When the heating roller 17 is grounded, a transfer / fixing bias VTb (secondary transfer bias) composed of a DC voltage having a polarity opposite to that of the toner (positive polarity in the present embodiment) is applied to the transfer / fixing roller 14f during transfer / fixing. Apply. As described above, the transfer rate of the color toner image is 98% or more due to the use of the polymerization toner as the toner of the developer for forming the color toner image and the electrostatic force of the transfer / fixing bias VTb at the time of transfer / fixing. Thus, the transfer failure that tends to occur when the toner layer thickness of the color toner image on the adhesive transfer belt 14a is large (thick) is suppressed.

After the Y, M, C and K superposed color toner images are transferred and fixed on the recording paper P,
The paper is discharged through 8 to a tray outside the apparatus.

After the transfer and fixing, the adhesive transfer belt 14a
A cooling fan RFa is vertically arranged across the adhesive transfer belt 14a.
The transfer residual toner remaining on the peripheral surface of the adhesive transfer belt 14a after the transfer after being cooled in the cooling unit RE having
The adhesive transfer belt is cleaned by an adhesive transfer belt cleaning device 19a which is a cleaning means for the adhesive transfer belt provided opposite to the driven roller 14e with the adhesive transfer belt 14a interposed therebetween.

Adhesive transfer belt 14a in cooling section RE
Is preferably cooled to a constant temperature of 50 ° C. or lower, preferably 30 to 40 ° C. By cooling the adhesive transfer belt 14a in the cooling unit RE, the adhesive transfer belt 14
The change in physical properties such as volume resistivity and adhesiveness of a is prevented.
Further, in the cooling section RE, not only the cooling of the adhesive transfer belt 14a but also the rise of the temperature of the surrounding air is prevented, the sensitivity characteristic and the potential characteristic of the photosensitive drum 10 are prevented from changing, and various characteristics of the developer are prevented. To prevent changes. Further, fusion of the toner to the photosensitive drum 10 is prevented.

The adhesive transfer belt 14a cooled in the cooling section RE is black (K) so that an image can be formed again.
In synchronization with the formation of the toner image on the photoreceptor drum 10, the sheet is conveyed to a transfer area (no symbol) formed of a nip portion Nc of K. As described above, the adhesive transfer belt 14 a
Therefore, the deterioration of the process members such as the photosensitive drum 10 can be prevented without heating the process members such as the photosensitive drum 10.

In the above, when the toner image on the image forming body for each color is transferred to the intermediate transfer body, as described above, the adhesive transfer belt 14a has a volume resistivity of 10 ⁸ Ω · cm or more.
And 10 ^{1 2} Omega · cm or less, so as to face the primary transfer roller 14c to the photosensitive drum 10 across the pressure-sensitive transfer belt 14a provided in a state of pressing the photosensitive drum 10, by a coating such as silicon rubber or urethane rubber The adhesive transfer belt 14a having an adhesive property forms a nip portion Nc which is a transfer area (no reference numeral) with the photoreceptor drum 10, and has a polarity opposite to that of the toner (in the present embodiment, as shown in FIG. 2). A transfer bias VTa composed of a DC voltage (positive polarity) is applied to the primary transfer roller 14c, and the nip N
c and the electrostatic force Fa of the transfer bias VTa, the photosensitive drum 1
The transfer of the toner image on the transfer belt 0 to the adhesive transfer belt 14a is performed. At this time, the toner image on the photosensitive drum 10 is attracted by the electrostatic force Fa of the transfer bias VTa on the toner image previously transferred onto the adhesive transfer belt 14a by the adhesive force of the adhesive transfer belt 14a. Is sucked, the subsequent toner image is superimposed and transferred on the previous toner image, and the superimposed color toner image is favorably transferred to the adhesive transfer belt 14a. At the time of such transfer, if the volume resistivity of the adhesive transfer belt 14a is low, the transfer bias VTa leaks to the photosensitive drum 10, and no bias voltage is applied to the toner image. Also, if the volume resistivity is high, toner repelling due to the transfer bias VTa occurs. In any case, good transfer is not performed. Therefore, the volume resistivity of the adhesive transfer belt 14a is set to 10 ⁸ Ω.
It is preferably set to not less than · cm and not more than 10 ¹² Ω · cm.

Further, due to the adhesive force of the adhesive transfer belt 14a applied to the nip portion Nc and the electrostatic force Fa of the transfer bias VTa, the adhesion of the photosensitive drum 10 across the toner image is maintained, and drive unevenness occurs. The driven rotation (drive) of the photosensitive drum 10 by the adhesive transfer belt 14a is performed without the need.

As described above, the transferability is improved by the adhesive force of the intermediate transfer member made of the adhesive belt member and the electrostatic force due to the application of the transfer bias, and the adhesive force and the electrostatic force that do not cause driving unevenness are improved. A driving method using an intermediate transfer body using force is provided, and image unevenness due to driving unevenness of the intermediate transfer body (image unevenness due to poor registration).
It is possible to provide an image forming apparatus in which generation of an image is prevented.

In the above, when the toner image on the intermediate transfer member is transferred to the transfer material, as described above, the adhesive transfer belt 14a has a volume resistivity of 10 ⁸ Ω · cm or more and 10 ¹² Ω · cm.
cm or less, and the above-mentioned polymerized toner is used as a developer toner used for forming a toner image.
As shown in (1), a transfer / fixing bias VTb composed of a DC voltage having the opposite polarity (positive polarity in the present embodiment) to the toner is applied to the transfer / fixing roller 14f, and the electrostatic force Fa of the transfer / fixing bias VTb causes adhesion. The color toner image on the transfer belt 14a is transferred to the recording paper P.
At this time, the use of the above-described polymerized toner as the developer toner prevents the occurrence of fog since there is no fine toner. Further, the polymerized toner has a good charge controllability and the transferability is improved.
The transfer rate of the color toner image onto the adhesive transfer belt cleaning device 19b (see FIG. 1 and not shown in FIG. 3) is used to clean the transfer residual toner on the adhesive transfer belt 14a when the transfer rate of the color toner image to the toner is 90% or more. Is reduced. Further, the use of a polymerized toner as the toner of the developer and the transfer / fixing bias VT
b, the color toner image on the photosensitive drum 10 is repelled by the repulsion of the electrostatic force Fb of the transfer / fixing bias VTb due to the application of “b”, so that the superimposed color toner image is favorably transferred to the recording paper P. Is performed. The transfer rate of the color toner image from the adhesive transfer belt 14a to the recording paper P is 9
The transfer failure is set to 8% or more, and transfer failure which is likely to occur when the toner layer thickness of the color toner image on the adhesive transfer belt 14a is large (thick) is suppressed. At the time of such transfer, if the volume resistivity of the adhesive transfer belt 14a is low, the transfer bias VT
a leaks to the heating roller 17 through the recording paper P, and the bias voltage is not applied to the color toner image. Also, if the volume resistivity is high, the transfer / fixing bias V
Separation discharge occurs due to Tb, and the color toner image on the recording paper P is disturbed. In any case, good transfer is not performed. For this reason, it is preferable to set the volume resistivity of the adhesive transfer belt 14a to 10 ⁸ Ω · cm or more and 10 ¹² Ω · cm or less.

As described above, the use of the polymerized toner as the toner of the developer prevents the occurrence of fog since there is no fine toner. Further, the charge controllability is good, the transfer rate of the color toner image from the intermediate transfer member to the transfer material is good, and the load of cleaning the intermediate transfer member is reduced. In particular, using a polymerized toner as a developer toner,
By applying a transfer / fixing bias at the time of transfer / fixing, the transfer rate of the color toner image is further improved, and a transfer failure which is likely to occur when the toner layer thickness (thickness) of the color toner image on the intermediate transfer member is large. Be deterred.

[0064]

According to the first aspect of the present invention, the transferability is improved by the adhesive force of the intermediate transfer member made of the adhesive belt member and the electrostatic force due to the application of the transfer bias. Provided is a driving method using an intermediate transfer body that uses an adhesive force and an electrostatic force that do not allow the image to be formed, and provides an image forming apparatus that prevents the occurrence of image unevenness due to drive unevenness of the intermediate transfer body (image unevenness due to poor registration). It becomes possible.

According to the second aspect, it is possible to provide an image forming apparatus in which the heating of the intermediate transfer body in the transfer / fixing section is cooled by the cooling section, and the deterioration of process members such as the image forming body is prevented. .

According to the third aspect, the use of the polymerized toner as the toner of the developer prevents the occurrence of fog since there is no fine toner. Further, the charge controllability is good, the transfer rate of the color toner image from the intermediate transfer member to the transfer material is good, and the load of cleaning the intermediate transfer member is reduced. In particular, by using a polymerized toner as the developer toner and applying a transfer / fixing bias during transfer / fixing, the transfer rate of the color toner image is further improved, and the color toner image on the intermediate transfer member is improved. Transfer defects that tend to occur where the toner layer thickness is large (thick) are suppressed.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a transfer state of a toner image from an image forming body to an intermediate transfer body.

FIG. 3 is a diagram illustrating a transfer state of a color toner image from an intermediate transfer member to a transfer material.

[Explanation of symbols]

 Reference Signs List 10 photoconductor drum 11 scorotron charger 12 exposure optical system 13 developing device 14a adhesive transfer belt 14c primary transfer roller 14f transfer / fixing roller 15 paper feed cassette 16 timing roller 17 heating roller 100 process unit HLa, HLb halogen lamp Nc nip P Recording paper RE Cooling unit RFa Cooling fan ROa Press roller VTa Transfer bias VTb Transfer / fixing bias

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/16 103 G03G 21/00 350 2H200 15/24 9/08 361 21/00 350 384 F-term (reference) ) 2H005 AA21 AB06 FC03 2H030 AA01 AA06 AB02 AD01 AD04 BB02 BB42 BB46 2H035 CA07 CB01 CG03 2H071 CA02 CA05 DA09 DA15 DA27 EA04 EA18 2H078 AA01 AA33 BB01 BB12 CC06 DD03 DD29 DD40 DD42 DD31 DD31 DD31 DD31 DD53 GA34 GA45 GA57 GB25 GB40 HA02 HA12 HB03 HB12 HB22 HB28 JA02 JA09 JA12 JA25 JB22 JB32 JC03 JC07 JC16 JC18 MA02 MB02 MB04 MB06 NA02

Claims (3)

[Claims] 1. A method for transferring a toner image formed on a plurality of image forming bodies, superimposing the toner images on an intermediate transfer body, and forming a superimposed color toner image on the intermediate transfer body. An image forming apparatus for transferring and fixing the superimposed color toner image onto a transfer material after forming the nip portion with the image forming body as an adhesive belt member. Applying a transfer bias to the intermediate transfer body with the volume resistivity of the body being 10 ⁸ to 10 ¹² Ω · cm, by the adhesive force and the electrostatic force applied to the nip portion,
An image forming apparatus that drives the image forming body and transfers the toner image to the intermediate transfer body. 2. The image forming apparatus according to claim 1, wherein the intermediate transfer body is cooled by a cooling unit after transferring and fixing the superimposed color toner image on the transfer material. 3. A method according to claim 1, wherein a polymerization toner is used as a toner of a developer used for forming the toner image, and a transfer / fixing bias is applied during transfer / fixing from the intermediate transfer member to the transfer material. The image forming apparatus according to claim 1.