JPH05119642A - Electrophotographic copying device - Google Patents

Abstract

PURPOSE:To efficiently clean the surface of an intermediate transfer belt member by arranging a magnetic brush cleaning device in a cleaning part and housing a specified carrier in the cleaning part. CONSTITUTION:An electrostatic charge image is formed on a photosensitive body 1 and developed by developer. Besides, the obtained toner image is transferred on the intermediate transfer belt member 200 and the toner image on the member 200 is transferred on a transfer paper 204. Thereafter, the toner image is fixed. Then, the magnetic brush cleaning device is installed in the cleaning part 7 for eliminating residual toner on the surface of the belt member 200 and the carrier covered with a covering material obtained by scattering an electrical conductive substance is housed in the cleaning part 7. Thus, the surface of the belt member 200 can be efficiently cleaned without splashing the toner or damaging the member and many copied sheets with excellent quality can be stably obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine (including an electrostatic copying machine), and more specifically, it transfers a toner image on a photoreceptor to an intermediate transfer belt member and transfers the toner image on the member. The present invention relates to an electrophotographic copying apparatus in which a magnetic brush cleaning device is arranged in a cleaning unit that removes residual toner on the surface of the member after transferring to paper, and a specific carrier is housed in the cleaning unit.

[0002]

2. Description of the Related Art A method of developing an electrostatic charge image is roughly classified into a liquid developing method using a developer in which various pigments and dyes are finely dispersed in an insulating organic liquid, a cascade method, a magnetic brush method, There is a dry development method that uses a fine powder developer called a toner in which a colorant is dispersed and contained in a natural or synthetic resin such as a powder cloud method, but it is currently available because a copy is obtained in a dry state. The dry development method is the mainstream.

In the dry developing system, after an electrostatic charge image (latent image) is formed on an image carrier (photoreceptor), this is visualized with toner, and the obtained toner image is transferred onto a transfer paper, Then, by fixing, a copy is obtained. Further, since the transfer paper is conveyed in a straight line, the toner image can be easily transferred to, for example, a postcard, so the toner image obtained by visualization is once transferred to the intermediate transfer belt member. After that, a method of transferring the toner image on the member to a transfer paper and then fixing the toner image is also adopted.

Dry developing systems are roughly classified into those using a one-component developer (consisting of toner only) and those using a two-component developer (consisting of carrier and toner).
In any case, it is desirable that all the toner images visualized by such a developer are ideally transferred to the transfer paper. However, for example, in the system in which the toner image is once transferred to the intermediate transfer belt member, the toner that cannot be completely transferred remains on the intermediate transfer belt member, and therefore this residual toner must be removed by a cleaning device.

As a method for cleaning the residual toner (untransferred toner), it is general to use (1) a fur brush, (2) a blade, (3) a magnetic brush or the like. However, the fur brush method requires a suction mechanism for sucking the toner removed by the brush, and has the drawbacks that the apparatus becomes large and the toner is easily scattered. Further, the blade method has a drawback that it is difficult to completely remove the residual toner and the intermediate transfer belt member is easily damaged because the particle size of the toner has been reduced in recent years with the demand for higher image quality. ..

In the cleaning by the magnetic brush method, the residual toner (untransferred toner) is brought into contact with the cleaning carrier to be triboelectrically charged, and the residual toner is adsorbed on the magnetic brush by the bias electric field. It has the feature that it does not exist and does not damage the contact member (intermediate transfer belt member), but it has a problem that the cleaning carrier used is required to have strict characteristics in order to carry out effective cleaning. More specifically, in order to effectively carry out triboelectric charging, it is desirable that the carrier resistance is high, and the charge generated between the toner and the carrier is less likely to leak as the carrier surface resistance is higher. On the other hand, at the time of cleaning, if the carrier resistance is high, the counter charge of the carrier is likely to remain, the force that works to prevent the toner from adhering to the collecting roller works, and the cleaning electric field becomes weak.
At the time of cleaning, it is desirable that the carrier has a low resistance so that the carrier has a low resistance.

[0007]

Therefore, the present invention has been made based on the above-mentioned technical background, and an electrostatic charge image is visualized by using a toner, and the obtained toner image is transferred to an intermediate transfer belt member. An electrophotographic copying apparatus that transfers the toner image on the member to a transfer paper and then fixes the toner image on the member, and efficiently cleans the surface of the intermediate transfer belt member without scattering the toner or damaging the member. It is an object of the present invention to provide an electrophotographic copying apparatus which can be carried out and can stably obtain a large number of good quality copies.

[0008]

As a result of intensive studies to solve the above-mentioned problems, the present inventors have arranged a magnetic brush cleaning device in a cleaning section for removing residual toner on the surface of an intermediate transfer belt member, and The inventors have found that an electrophotographic copying machine in which a carrier covered with a coating material in which a conductive material is dispersed is housed in a cleaning portion does not meet the above object, and have completed the present invention.

That is, according to the present invention, an electrostatic charge image is formed on a photoconductor, visualized by a developer, the obtained toner image is transferred to an intermediate transfer belt member, and thereafter, the image is formed on the member. In an electrophotographic copying apparatus that transfers a toner image onto a transfer paper and then fixes the toner image, a magnetic brush cleaning device is installed in a cleaning unit for removing residual toner on the surface of the intermediate transfer belt member, and the cleaning is performed. There is provided an electrophotographic copying apparatus characterized in that a carrier coated with a coating material in which a conductive substance is dispersed is housed in a portion.

In the following, the device according to the invention will be explained in more detail with reference to FIG. 1 in the context of the copying process. First, the surface of the photoconductor (inorganic photoconductor, organic photoconductor) 1 is uniformly charged with positive or negative charge by the charging charger 2. Positive charging or negative charging is selected depending on the type (property) of the photosensitive member 1. For example, if the photosensitive member is a Se type photosensitive member, positive charging is performed. Image exposure is performed on this by an optical system 3 to form an electrostatic charge image, and the electrostatic charge image is developed.
Is visualized by.

The developing section 4 contains a developer, for example, a two-component developer composed of a carrier (magnetic carrier) and toner. The developer is held on the developing sleeve 41 containing the magnet 411, and develops the electrostatic charge image on the photoconductor 1.
Since only the developing toner is consumed each time development is performed, the sensor 42 detects the toner concentration of the developer and new developing toner is supplied so that the toner concentration is always constant. .. 43 is a paddle wheel for stirring the developer. If necessary,
A bias is applied to the developing sleeve 41.

Subsequently, the toner image on the photosensitive member 1 is once transferred onto the intermediate transfer belt 200 via the transfer bias roller 201. The intermediate transfer belt 200 is moved by the driving roller 202, and when it comes into contact with the transfer paper 204, the toner image is transferred to the 204 via the paper transfer bias roller 203.
Is transcribed to. Then, the transfer paper 204 proceeds to the fixing step, and the toner image is fixed. Part of the untransferred toner is present on the intermediate transfer belt 200, and the toner is cleaned by the magnetic cleaning device 7 to be ready for the next transfer.

The toner remaining on the photosensitive member 1 is cleaned by the blade cleaning device 300. Here, the PCC charger 301 pre-charges the remaining toner so that the remaining toner is evenly charged, the fur brush 303 loosens the toner, and the cleaning blade 304 scrapes the toner. The scraped toner is squeezed out of the apparatus by the collecting roller 302, and the photoconductor 1 is ready for the next charging.

Cleaning unit 7 in the apparatus of the present invention
Uses a magnetic brush cleaning method, in which a cleaning carrier (magnetic carrier) as a cleaning agent is stored. A positive or negative bias of about 100 to 500 V is applied to the cleaning roller 71 containing a magnet (not shown), and the cleaning agent is held on the cleaning roller 71 by the magnet. Here, the polarity of the bias applied to the cleaning roller 71 is opposite to the polarity of the toner in the two-component developer.

The residual toner is electrostatically adsorbed by the cleaning agent and is transferred together with the cleaning agent to the scooping rollers 72 to 73. Behind the pumping roller 73,
A residual toner collecting roller 74 to which a bias having the same polarity as that of the cleaning roller 71 is applied is arranged, and only the residual toner is transferred to the collecting roller 74. The bias applied to the collecting roller 74 is the cleaning roller 71.
It is preferable that the bias is relatively higher than the bias applied to the device, and about 200 to 800 V is appropriate.

Immediately after the residual toner is transferred from the scooping roller 73 to the collecting roller 74, the cleaning carrier is
It is scraped off by the cleaning scraper 75 that is in contact with the scooping roller 73, and is returned to the surface of the cleaning roller 71 again. On the other hand, the residual toner transferred to the collecting roller 74 is scraped off by the collecting blade 76 which is in contact with the collecting roller 74 and taken out of the cleaning section 7 by the discharging screw 77. Used as toner. The collecting roller 74 cleaned by the collecting blade 76 is used for collecting the next residual toner.

Generally, the cleaning carrier has a lower residual toner concentration than the developing carrier and is used at a maximum of 2% by weight, usually about 1% by weight (the toner concentration in the developing section 4 is 2 to 7% by weight). In the cleaning section 7, there are many occasions where the cleaning carriers rub against each other, and the toner tends to be easily fused and the spent toner tends to adhere to the cleaning carrier. Therefore, in the non-coated cleaning carrier, the spent toner adheres to the carrier at an early stage and the Q / M is reduced, and the image quality due to insufficient cleaning is significantly reduced.

In the present invention, as described above, a carrier coated with a coating material in which a conductive substance is dispersed is used as the cleaning carrier. By providing the coating layer containing a conductive substance, the carrier resistance can be easily controlled to a desired value. Further, as the coating material, one made of a material having a low surface energy (that is, a material having excellent peelability) is particularly preferable.
By providing the coating layer made of the low surface energy resin, it becomes possible to prevent the spent toner from adhering to the cleaning carrier. As a result, when such a cleaning carrier is used, a constant charge amount (Q / M) can be obtained for a long period of time, so that cleaning failure does not occur on an image.

Examples of the resin for the coating layer in the cleaning carrier used in the present invention include the following resins, which may be used alone or in combination.

Polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene and chlorosulfonated polyethylene; polystyrene, acrylic resin (eg polymethylmethacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl. Polyvinyl and polyvinylidene resins such as carbazole, polyvinyl ether, polyvinyl ketone, vinyl chloride / vinyl acetate copolymers, styrene / acrylic acid copolymers; silicone resins such as straight silicone resins composed of organosiloxane bonds or modified products thereof. (For example, modified products of alkyd resin, polyester, epoxy resin, polyurethane, etc.); polytetrafluoroethylene, polyvinyl fluoride, Polyesters such as polyethylene terephthalate; polyamide; Li vinylidene fluoride, fluorine resins such as polychlorotrifluoroethylene polyurethane; polycarbonates; -; epoxy resins such as urea amino resins such as formaldehyde resins.

Among these, preferred from the viewpoint of preventing the spent toner from adhering to the carrier are silicone resins or modified products thereof and low surface energy resins such as fluorine resins. In addition, as a commercially available product of silicone resin (however, straight silicone resin), Shin-Etsu Chemical Co., Ltd. KR27
1, KR255, KR251; SR made by Toray Silicon Co., Ltd.
2400, SR2406, etc., and as the modified silicone resin, Shin-Etsu Chemical Co., Ltd. KR206 (alkyd resin modified product), KR3093 (acrylic resin modified product), E
S1001N (epoxy resin modified product); Torre Silicon Co. SR2115 (epoxy resin modified product), SR211
0 (modified alkyd resin) and the like.

As the fluorine resin, polytetrafluoroethylene (PTFE), tetrafluoroethylene /
Hexafluoropropylene copolymer (FEP), polychlorotrifluoroethylene (PCTFE), polyvinylidene fluoride (PVDF), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (P
FA) and the like, and in addition to these, it is also possible to use one in which a filler is dispersed in a fluororesin.

The amount of the coating layer resin used is generally 0.5 to 50 parts by weight per 100 parts by weight of the carrier core material.

Examples of the conductive substance dispersed in the coating layer of the cleaning carrier used in the present invention include carbon, metal, titanium oxide, zinc oxide and the like. Further, as the core material of the cleaning carrier, conventionally known materials such as iron, magnetite, ferrite and steel are used. The particle size is usually 20 to 1000 μm, preferably 3
It is about 0 to 300 μm.

The cleaning carrier can be prepared by a known method such as a coating method and a spray drying method. Specifically, a method of dispersing a conductive substance in a solution in which a resin for a coating layer is dissolved and coating a carrier core material (magnetic material) in a fluidized bed or the like, or a resin for a coating layer without using a solvent, A method of producing cleaning carrier particles by mixing a magnetic substance and a conductive substance by a heat kneading method and performing a pulverizing treatment or a spheroidizing treatment can be mentioned.

The cleaning carrier used in the present invention preferably has a resistance value within a predetermined range. That is, the specific resistance when a DC electric field of 50 V / cm is applied is 1.5 × 10 ^{7 to} 1.4 × 10 ¹⁵ Ωcm, and the specific resistance when a DC electric field of 500 V / cm is applied is 2.5 to It is preferably 10 ^{8 to} 1.2 × 10 ¹⁵ Ωcm.

For good cleaning, the resistance of the cleaning carrier must be sufficiently low to maximize the cleaning electric field. However, if the resistance is set too low, only the toner or the carrier will be transferred from the cleaning agent to the intermediate transfer belt, and the intermediate transfer belt will be contaminated. On the other hand, if the resistance becomes too high, the cleaning electric field becomes too small, and the cleaning property deteriorates. Further, the toner will not be transferred to the toner collecting roller 74. Therefore,
When the bias of the toner collecting roller 74 is increased,
There is a problem that the carrier also moves to the toner collecting roller 74. Therefore, by defining the carrier resistance value within the above range, the above-mentioned drawbacks are eliminated.

Here, the measuring method of the specific resistance is as follows. After allowing the sample to flow into a cell formed by facing two electrode plates each having an area of 10 cm ² (length 4 cm, width 2.5 cm) at an interval of 2 mm, the sample having a height of 15 mm was placed in this state. The tapping operation in which the sample is dropped from the position onto the flat plate is repeated 30 times to tightly fill the cell with the sample. Then remove the excess sample on the cell and then
50V for each electrode plate under the environment of 20 ℃ and 60% RH
/ Cm and 500 V / cm of the direct current electric field is applied (the electric field application part is the part of a and b of FIG. 2) and the specific resistance is obtained. It should be noted that the two applied voltages are defined as 50 V / cm.
This is because a carrier satisfying the value of 1 becomes conductive when 500 V / cm is applied and measurement cannot be performed.

In the present invention, the toner charge amount (hereinafter referred to as Q / M) of the cleaning agent is preferably 20 to 90 μc / g, more preferably 25 to 75 μc / g.
Is. The reason why the above Q / M range is preferable is 20 μm.
If it is less than c / g, the toner adhering to the belt 200 cannot be transferred onto the cleaning roller 71 promptly,
This is because if it exceeds 90 μc / g, the toner cannot be transferred to the toner recovery roller 74, which increases the toner concentration of the cleaning agent and reduces the cleaning electric field (cleaning failure). By setting the toner charge amount of the cleaning agent in the range of 20 to 90 μc / g, the toner can be transferred to the cleaning roller 71 promptly, and the toner can be transferred to the toner recovery roller 74 promptly. It will be.

In the present invention, the toner concentration of the cleaning agent housed in the apparatus for cleaning the intermediate transfer belt is preferably 0.2 to 3.0% by weight, more preferably 1 to 3.0% by weight. It is 2% by weight. If the toner concentration is less than 0.2% by weight, the probability that the carriers will come into contact with each other in the cleaning agent becomes high, the coating layer of the carrier is scraped very quickly, the spent toner adheres to the carrier, and the carrier charging ability is Disappears. In addition, this toner density control is
It is performed by a sensor (not shown) similar to the developing unit 4 shown in FIG.

As described above, every time cleaning is performed, toner is added to the cleaning unit 7 and the toner is collected by the toner collecting roller 74. At this time, the amount of toner added and the amount of toner taken (balance) are not always constant, so cleaning agent should be flown through the sensor for frequency detection, and if it is detected that the frequency is lower than the set value, the toner supply unit By replenishing the toner and stopping the toner replenishment when the number of cycles becomes higher than the set frequency, the toner concentration of the cleaning unit 7 is always controlled to be constant, and the carrier coating layer is misaligned due to the lower toner concentration. The problem due to the above does not disappear, and the bias effect of the cleaning unit cannot be expected due to the increase in the toner concentration.

If there is no toner in the cleaning agent (toner concentration = 0%), the fluidity of the cleaning agent in the developing section is not good, and the agent can be uniformly supplied in the roller axial direction on the sleeve of the cleaning roller 71. Disappear.
In particular, if the carrier shape is an irregular type, the surface is uneven, resulting in extremely poor fluidity.

When the cleaning agent contains the toner, the fluidity becomes good even with an irregular type carrier.
It is considered that this is because the toner plays the role of a lubricant. On the other hand, if the toner concentration exceeds 3%, the collection roller 74
It becomes difficult for the toner to migrate. This is because the bias effect of the toner collecting roller 74 becomes insufficient. Therefore, when the bias is increased, not only the toner but also the carrier is transferred to the toner collecting roller 74, and the cleaning agent runs short.
Insufficient supply of the agent to the cleaning agent causes gradual cleaning failure.

As an example of toner concentration control, generally, a developer is flowed while a coil is wound around a cylinder, a change in the frequency is captured, and when the frequency becomes lower than a preset frequency, toner is replenished, In addition to the above control method in which the toner supply is stopped when the frequency becomes higher than a preset value, the reference pattern is developed to determine whether the image density of the pattern is higher or lower than the reference. Judge, turn off toner supply, O
It is possible to employ a control method of N or a method of turning ON / OFF the toner supply by comparing the reflection density of the cleaning agent with a reference.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
All parts shown below are based on weight.

Example 1 As a coating material for a cleaning carrier, a coating liquid was prepared according to the following formulation. Silicone resin (SR2400: manufactured by Toray Silicone) 240 parts Ketjen Black EC / DJ600 (manufactured by Lion Akzo) 5 parts Toluene 1500 parts

5 kg of oxidation-treated iron powder having an average particle diameter of 100 μm was put into a rotating disk type fluidized bed particle coating device, and the coating liquid having the above formulation was heated at 80 ° C. while flowing the iron powder.
The coated material, which has been sprayed under heating, is taken out of the coating apparatus and placed in a constant temperature bath, and heated at 200 ° C. for 2 hours to cure the silicone film, thereby obtaining a cleaning carrier provided with a coating layer. ..

A two-component black developer (for FT-4060: manufactured by Ricoh Co., Ltd.) and the above cleaning carrier are used in a copying apparatus shown in FIG. 1 (a selenium-based photoreceptor is used as a photoreceptor).
The surface potential of the photoconductor 1 is uniformly charged so that the surface potential becomes +800 V, a bias of +250 V is applied to the cleaning roller 71, and a bias of +300 V is applied to the collecting roller 74), and copying is performed at a rate of 30 sheets per minute. And the toner consumed in the developing section 4 was replenished.

After the continuous copying of 500 sheets, the main switch is turned off during the copying process, the intermediate transfer belt is taken out, and the adhesive tape is adhered onto the intermediate transfer belt immediately after passing through the cleaning section. Remove the dirt on the adhesive tape and attach the adhesive tape to copy paper (Ty
pe6200: manufactured by Ricoh Co., Ltd.), and its density was measured with a Macbeth densitometer.
Was very clean at 0.10. 10000 more
When I looked at the first sheet, no stain was found.

Example 2 As a cleaning carrier coating material, a coating liquid was prepared according to the following formulation. Polytetrafluoroethylene (solid content 60%: D-1: Daikin Industries, Ltd.) 250 parts Ketjen Black EC / DJ600 (Lion Akzo) 5 parts Fluorosurfactant (FC-134: Sumitomo 3M) 1% aqueous solution of 1500 parts

5 kg of oxidized iron powder having an average particle diameter of 100 μm was put into a rotating disk type fluidized bed particle coating device, and the coating liquid having the above formulation was heated at 80 ° C. while flowing the iron powder.
The coating material applied by spraying under heating was taken out from the coating apparatus, placed in a constant temperature bath, and heated at 350 ° C. for 2 hours to cure the fluorine film, thereby obtaining a cleaning carrier provided with a coating layer. ..

Two-component black developer (ARTAGE5330
For: Ricoh) and the cleaning carrier shown in FIG.
The copying machine shown in FIG. 1 (using an organic photoconductor as a photoconductor, uniformly charged so that the surface potential of the photoconductor 1 becomes −600 V, a bias of −250 V on the cleaning roller 71, and a recovery roller 74. A bias of −300 V was applied), and a copy was obtained at a rate of 30 sheets per minute, and the toner consumed in the developing section 4 was replenished.

After continuously copying 500 sheets, the intermediate transfer belt was tested for cleaning property in the same manner as in Example 1, and the same result as in Example 1 was obtained. 100 more
No dirt was seen when the 0th sheet was viewed.

Example 3 Color copying was performed using the color copying apparatus shown in FIG. First, in the developing units 500, 501 and 502,
A color agent (cyan, magenta and yellow agent: manufactured by Ricoh Co., Ltd.) for ARTAGE 5300 is set. The cleaning carrier prepared in Example 2 is set in the cleaning unit 7 of the intermediate transfer belt. In the copying process, first, the charging is performed by the charging charger 2, the optical system 3 exposes the light through a blue filter, and the developing unit 502 develops (at this time, the agents on the sleeves of the developing units 500 and 501 are spike cutting means, Cut with). Then, this image is transferred to the intermediate transfer belt 200 (at this time, the agent on the sleeve of the cleaning unit 7 is the developing units 501 and 502).
And cut it as well). Subsequently, the photoconductor 1 is cleaned by the blade cleaning device 300.

Next, the optical system 3 is charged by the charging charger 2.
Then, it is exposed through a green filter and developed in the developing section 501 (at this time, the agents on the sleeves of the developing sections 500 and 502 are cut off). This image is transferred to the intermediate transfer belt 200.
Transfer to the upper yellow image. The photoconductor 1 is cleaned by the blade cleaning device 300. Next, it is charged by the charging charger 2, exposed through the red filter by the optical system 3, and developed by the developing section 500 (at this time, the agents on the sleeves of the developing sections 501 and 502 are cut off).
Further, this image is transferred onto the yellow magenta image on the intermediate transfer belt 200 to obtain a color image.

In this state, the paper is transferred onto the transfer paper 204 by the paper transfer bias roller 203, and the transfer paper 20 is transferred.
Step 4 proceeds to the fixing step. The intermediate transfer belt 200 is brought into contact with the sleeve on the cleaning unit 7 for the first time here, and is cleaned to prepare for the next transfer. The photoconductor 1 is cleaned by the blade cleaning device 300.
With this method, the cleaning property after passing 500 sheets is
It was as good as in Example 1.

Example 4 As a coating material for a cleaning carrier, a coating liquid was prepared according to the following formulation. Acrylic resin (polymethylmethacrylate: molecular weight 50,000) 70 parts Ketjenblack EC / DJ600 (manufactured by Lion Akzo) 3 parts Toluene 2000 parts

5 kg of oxidation-treated iron powder having an average particle diameter of 100 μm was put into a rotating disk type fluidized bed particle coating device, and the coating liquid having the above formulation was heated at 50 ° C. while flowing the iron powder.
It was sprinkled under heating to obtain a cleaning carrier provided with a coating layer.

A test concerning the cleaning property was carried out in the same manner as in Example 1 except that the obtained cleaning carrier was used. As a result, the stains on the intermediate transfer belt after 500 sheets were the same as in Example 1. It was Ta-5000
ID = 0.3 on the first sheet, which was easier to stain than in the case of Example 1.

Comparative Example A cleaning carrier was prepared in the same manner as in Example 1 except that Ketjenblack EC / DJ600 was omitted from the formulation of the coating material for cleaning carrier in Example 1. Using this cleaning carrier, a test relating to the cleaning property was conducted in the same manner as in Example 1. As a result, the 100th continuous copy showed that scumming had already occurred on the copy due to the poor cleaning property.

[0051]

According to the electrophotographic copying apparatus of the present invention, the toner image on the photosensitive member is once transferred to the intermediate transfer belt member, and then the toner image on the member is transferred and fixed on the transfer paper. A magnetic brush cleaning device is installed in a cleaning unit for removing residual toner on the surface of the intermediate transfer belt member, and a carrier covered with a coating material in which a conductive substance is dispersed is housed in the cleaning unit. Therefore, the surface of the intermediate transfer belt member can be efficiently cleaned without scattering of toner or damage to the member.

In the electrophotographic copying apparatus of the second aspect, since the coating material of the carrier is made of a resin having a low surface energy, the surface of the intermediate transfer belt member is cleaned by attaching the spent toner to the carrier. Without it, the effect of stable implementation is added.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining an embodiment of a copying apparatus according to the present invention.

FIG. 2 is a schematic diagram of a cell for explaining a method for measuring a carrier specific resistance.

FIG. 3 is a schematic diagram for explaining another embodiment of the copying apparatus according to the present invention.

[Explanation of symbols]

 1 Photoreceptor 2 Charging Charger 3 Optical System 4 Developing Section 7 Cleaning Section 41 Developing Sleeve 42 Sensor 43 Paddle Wheel 71 Cleaning Roller 72, 73 Pumping Roller 74 Collecting Roller 75 Cleaning Scraper 76 Collecting Blade 77 Discharging Screw 200 Intermediate Transfer Belt 201 Transfer Bias Roller 202 Drive roller 203 Paper transfer bias roller 204 Transfer paper 300 Blade cleaning device 301 PCC charger 302 Toner recovery roller 303 Fur brush 304 Cleaning blade 411 Magnet 500, 501, 502 Development unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takahisa Kato 1-3-6 Nakamagome, Ota-ku, Tokyo Stock company Ricoh Co., Ltd. (72) Tomomi Suzuki 1-3-6 Nakamagome, Ota-ku, Tokyo Shares Company Ricoh

Claims (2)

[Claims] 1. An electrostatic charge image is formed on a photoreceptor, visualized with a developer, the obtained toner image is transferred to an intermediate transfer belt member, and then the toner image on the member is transferred onto a transfer paper. In the electrophotographic copying apparatus that fixes the toner image after transfer, a magnetic brush cleaning device is installed in the cleaning unit for removing the residual toner on the surface of the intermediate transfer belt member, and a conductive substance is placed in the cleaning unit. An electrophotographic copying apparatus comprising a carrier coated with a dispersed coating material. 2. The electrophotographic copying machine according to claim 1, wherein the coating material for the carrier is made of a resin having a low surface energy.