JPH06289679A - Image forming method - Google Patents

Abstract

PURPOSE:To provide an image forming method in which ozone or NOX is not produced at all and by which residual toner on the surface of an image carrier is effectively removed and recovered. CONSTITUTION:In this image forming method, a toner image is formed on the surface of the image carrier 1 by installing the image carrier 1 consisting of a translucent optical semiconductor material and a developing roll 5 forming a magnetic brush, and radiating an optical signal from the back surface of the image carrier 1. An electrostatic charging and cleaning roll 12 having a permanent magnetic member 13 is installed near the developing roll 5, and the magnetic brush consisting of magnetic carrier and magnetic toner having volume specific resistivity of <10<5>OMEGA.cm is formed on the surface of the roll 12, then the image carrier 1 is electrostatically charged and the residual toner is removed and recovered, whereby the excess toner is supplied to the developing roll 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic carrier which is irradiated with an optical signal from the back surface of an image carrier made of an optical semiconductor material having a light-transmitting property and which is conveyed by a developing roll composed of a permanent magnet member and a sleeve. The present invention relates to an image forming method for selectively attaching magnetic toner in a magnetic developer composed of magnetic toner, and in particular, there is no generation of corona products from a charging means and / or a transfer means, The present invention relates to an image forming method improved so that residual toner on the surface can be effectively cleaned and collected.

[0002]

2. Description of the Related Art Conventionally, as a means for reproducing information such as a document or a figure, means such as electrophotography, electrostatic recording or electrostatic printing has been generally used. For example, in an electrophotographic copying machine or a facsimile, a toner in which an electrostatic latent image is formed on a photoconductor layer or a dielectric layer and then charged to a predetermined polarity by frictional charging with a carrier by a magnetic brush method, Alternatively, an image forming method is often adopted in which a magnetic toner containing a binder resin and magnetic powder as main components is selectively adhered to the latent image to obtain a reproduced image. However, when such an image forming method is adopted, an electrostatic latent image forming means including a charging means for uniformly charging the image carrier in advance is provided separately from the developing means in the image forming apparatus. Since it is necessary, there is a problem that the device becomes complicated and tends to increase in size.

Therefore, as disclosed in, for example, Japanese Patent Publication No. 55-30228, a magnetic toner having conductivity is magnetically adsorbed and held on a sleeve made of a non-magnetic conductive material, and the sleeve is opposed to the sleeve. An information signal is applied to the recording electrode while passing a sheet-shaped recording member between the recording electrode and the recording electrode, and electrostatic force is applied to the magnetic toner, and this magnetic toner is selectively adhered to the recording member. There is a suggestion to do so.

In addition to the above, many proposals have been made for the direct recording means. However, in all of them, the recording member is passed between the recording electrode and the counter electrode to perform the recording only by the electric means. Therefore, in order to obtain a good recorded image, it is necessary to strictly select various conditions such as the gap between the electrodes and the amount of toner supplied onto the recording member. Furthermore, when plain paper is used as the recording member, the surface resistance of the paper is greatly affected by environmental conditions such as humidity and temperature.Therefore, it is necessary to adjust the developing conditions according to these environmental conditions, There are problems such as not being able to record,
It has not been put to practical use yet.

On the other hand, an optical signal corresponding to the original image is radiated from the back surface of the image carrier made of an optical semiconductor material having translucency,
An image in which conductive magnetic toner conveyed by a developing roll including a permanent magnet member and a sleeve is selectively adhered to the surface of an image carrier to perform development, and the reproduced image is transferred and fixed on the surface of the recording member. Forming methods have also been proposed.

[0006]

In the back exposure type image forming method, a high voltage (5 to 8 kV DC) is applied to a metal wire as a charging means and a transfer means for stabilizing the charging of the image carrier. It uses a method that uses a corona. However, in this method, corona products such as ozone and NOx are also generated when corona is generated, so that environmental pollution is caused by an unpleasant odor.
Further, the corona product causes a problem in that the surface of the image carrier is deteriorated to cause image blurring or deterioration, and the dirt of the wire affects the image quality, resulting in image white spots and black streaks.

On the other hand, in the corona transfer method, since a corona charge having a polarity opposite to that of the developer is applied from the back surface of the recording material to electrostatically transfer the developer to the recording material, the recording is affected by humidity. There are problems that the resistance of the material changes, and it is difficult to transfer in the case of a recording material having a low resistance.

In the system utilizing corona discharge, the electric current to the image carrier or the recording material is only 5 to 30% of the supplied electric current, and most of the electric current flows to the shield plate. The power efficiency of the means or transfer means is low. For this reason, there is a problem that the amount of power consumption for ensuring a predetermined efficiency becomes large, and the capacity of the high-voltage transformer must be large.

Further, when a method of charging the surface of the image carrier with a fur brush or the like is adopted as the charging means, the toner remaining on the surface of the image carrier after transfer or the toner of fog is also rubbed, and the image There is a problem that the surface of the carrier is contaminated and the quality of the toner image thereafter is deteriorated.

The present invention solves the above-mentioned problems existing in the prior art, does not generate ozone and NOx, and can effectively clean and collect the residual toner on the surface of the image carrier. The purpose is to provide.

[0011]

In order to achieve the above object, in the present invention, an image carrier made of an optical semiconductor material having a light-transmitting property is movably provided and is formed in a hollow cylindrical shape by a non-magnetic material. A developing roll having a permanent magnet member having a plurality of magnetic poles on its surface is provided inside the sleeve so as to face the surface of the image carrier, and the frictional charging type is insulative to the magnetic carrier supplied onto the sleeve. The magnetic developer composed of magnetic toner is conveyed to the recording area formed between the sleeve and the image carrier by the relative rotation of the sleeve and the permanent magnet member, and corresponds to the original image from the back surface of the image carrier to the recording area. Image formation in which the magnetic toner in the magnetic developer is selectively adhered to the surface of the image carrier by irradiating an optical signal and the obtained toner image is transferred onto the recording member via the roller type transfer means. In the method, a charging / cleaning roll having a permanent magnet member having a plurality of magnetic poles on its surface as a constituent element is rotatably provided on the upstream side in the moving direction of the image carrier near the developing roll, facing the image carrier. A charging / cleaning agent composed of a magnetic carrier having a volume resistivity of less than 10 ⁵ Ω · cm and the magnetic toner is attached to the surface of the charging / cleaning roll to form a magnetic brush, and the magnetic brush is applied to the surface of the image carrier. After the surface of the image bearing member is rubbed and the residual toner is cleaned and collected, an image is formed by the developing roll, and an image is formed on the outer surface of the charging / cleaning roll. A technical means of supplying the excess magnetic toner to the developing roll through a mesh member made of a non-magnetic material formed so that only the excess magnetic toner passes through. It was adopted.

In the present invention, the charging / cleaning roll can be formed by arranging a plurality of magnetic poles extending in the axial direction of the outer peripheral surface at equal intervals in the circumferential direction, and made of an ordinary permanent magnet material in a cylindrical shape. Or a plurality of block-shaped permanent magnets are arranged on the outer periphery of the shaft member. Alternatively, a sleeve formed of a non-magnetic material in the shape of a hollow cylinder may be coaxially and relatively rotatably provided on the outer circumference of the charging / cleaning roll.

Next, when the volume resistivity of the magnetic carrier constituting the charging / cleaning agent of the present invention is 10 ⁵ Ω · cm or more, the charging potential on the surface of the image bearing member cannot be maintained at a predetermined value. However, the charging ability is insufficient, which is inconvenient. Further, the cleaning and collecting ability of the residual toner on the surface of the image bearing member is deteriorated with the insufficient charging ability, which is not preferable.

As the above-mentioned magnetic carrier, iron powder and ferrite particles (Ni-Zn system, Mn-Zn system, Cu-Z) used as a carrier in a general two-component developer are used.
n-type) and magnetite particles can be used.

The above magnetic carrier has an average particle size of 10 to 2
It is preferable to adjust the particle size to 00 μm before use. Incidentally, for example, fine particles having a size of 5 μm or less may be granulated to form the above-mentioned average particle size. The above magnetic powder can be used as it is, but after being coated with a resin (fluorine resin, styrene resin, polyester resin, epoxy resin, or a mixed resin thereof), conductive particles such as carbon black were added. Those are preferable. Further, a so-called binder type in which conductive particles are attached to the surface of a core material composed of the magnetic powder and a binder resin may be used.

The average particle size of the triboelectrification type magnetic toner constituting the magnetic developer and the charging / cleaning agent used in the present invention is 5 to 20 μm, preferably 6 to 16 μm, but the particle size is small. If there is, fog on the ground and toner scattering occur, which is not preferable. On the other hand, if the particle size is large, the resolution and developability are lowered, which is inconvenient.

Such a magnetic toner contains magnetic powder made of a compound or alloy containing iron, such as ferrite or magnetite, or an element exhibiting ferromagnetism such as cobalt or nickel. In addition, in order to uniformly disperse the magnetic powder in the toner, it is desirable to form the average particle diameter of 0.01 to 3 μm. The content may be in the range of 20 to 75% by weight.

Next, the volume resistivity of the magnetic toner is 10 ¹² Ω.
-If it is less than cm, the transferability and the charging property are deteriorated, which is not preferable. Next, the following resins can be used as the binder resin constituting the above magnetic toner.

When the fixing system is a heat fixing system (oven or hot roll), for example, the following thermoplastic resin,
That is, homopolymers obtained by polymerizing monomers such as styrenes, vinyl esters, α-methylene aliphatic monocarboxylic acid esters, acrylonitrile, methacrylonitrile, acrylamide, vinyl ethers, vinyl ketones, and N-vinyl compounds. Alternatively, a copolymer obtained by copolymerizing two or more of these monomers in combination, or a mixture thereof can be used. Further, a non-vinyl type resin such as a non-vinyl type thermoplastic resin such as a bisphenol type epoxy resin, an oil modified epoxy resin, a polyurethane resin, a cellulose resin, a polyether resin or a polyester resin, or a vinyl type resin such as those described above. Can be used.

Next, when the fixing system is the pressure fixing system, for example, the following pressure-sensitive resins, that is, higher fatty acids, higher fatty acid derivatives, higher fatty acid amides, waxes, rosin derivatives and alkyd resins are used. , Epoxy modified phenolic resin, Natural resin modified phenolic resin, Amino resin, Silicone resin, Urea resin, Acrylic acid or methacrylic acid and long chain alkyl methacrylate, Copolymerization oligomer of long chain alkyl acrylate, Polyolefin, Ethylene / vinyl acetate copolymer Examples thereof include a polymer, an ethylene / vinyl alkyl ether copolymer, and a maleic anhydride copolymer.

These resins can be arbitrarily selected and used by mixing them arbitrarily, but in order not to lower the fluidity when used as a toner, a resin having a glass transition point of more than 40 ° C. or a resin mixture. Is effective.

In addition to the above components, additives such as various pigments and dyes used in general dry developers may be contained, but the addition amount is 10% by weight or less in order not to lower the fixing property. It is good to say

The above magnetic toner can be manufactured, for example, as follows. That is, the raw materials are first kneaded by heating, cooled and solidified, then pulverized, and then classified to obtain toner particles having a predetermined particle size.

Next, the magnetic carrier constituting the magnetic developer has an average particle diameter of 10 to 100 μm and a volume resistivity of 10 ⁵ to 10 ¹⁰ Ω · cm (more preferably 10 ⁷ to 1).
It is preferable of 0 ⁹ Ω · cm). As such a magnetic carrier, not only particles made of a ferromagnetic material having the above-mentioned characteristics but also those obtained by dispersing these particles in a binder resin can be used, but magnetite and ferrite particles are most preferable. is there. Further, the above magnetic particles may be used as they are, or those in which a coating layer made of a resin material is provided on the surface of the magnetic particles may be used.

As the resin material for forming the above-mentioned coating layer,
Silicon resin, styrene-acrylic resin, polyester resin, maleic acid resin, acrylic acid resin, etc.
Examples thereof include copolymers and modified products. Further, a hardening agent may be used in combination to firmly fix the resin to the surface of the magnetic particles. Examples of such a curing agent include thermosetting compounds such as melamine and various amine salts.

Further, as a coating material, the adhesiveness with magnetic particles is improved, or the abrasion resistance is improved, the fusion of toner is prevented,
In addition to the above, a small amount of phenol resin, urea resin, alkyd resin, other filler, diluent, flexibility-imparting agent, etc. can be blended for the purpose of controlling toner chargeability and imparting fluidity to the developer. .

Next, as the transfer roll constituting the transfer means in the present invention, an outer shell layer made of a flexible elastic material such as rubber is attached to the outer periphery of a cored bar made of a rigid material such as a metal material. It may be configured as a slip transfer means that causes a slight amount of slip between the image carrier and the recording material. On the other hand, the outer shell layer may be hard, or the outer shell layer may be absent, and the pressure transfer means may have a small nip width formed between the outer shell layer and the image carrier. Alternatively, a conductive rubber roll may be used as the transfer roll to electrostatically transfer.

[0028]

With the above structure, generation of gases such as ozone and NOx due to corona discharge is eliminated, and residual toner on the surface of the image carrier can be cleaned and collected and supplied to the developing roller.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional explanatory view of essential parts showing an example of an image forming apparatus in an embodiment of the invention. In FIG. 1, reference numeral 1 denotes an image carrier, for example, a conductive layer 3 having a light-transmitting property and a photosensitive layer made of an optical semiconductor material having a light-transmitting property on a surface of a support 2 made of a light-transmitting material such as glass. 4 is attached,
It is formed in a hollow cylindrical shape, and is provided so as to be rotatable clockwise, for example. A protective layer made of a wear resistant material may be provided on the surface of the photosensitive layer 4.

A developing roll 5 is provided at an end of a developer tank 7 containing a magnetic developer 6 and is provided so as to face the image carrier 1. The developing roll 5 is configured by coaxially combining a permanent magnet member 8 having a plurality of magnetic poles on the surface and a hollow cylindrical sleeve 9 made of a nonmagnetic material such as an aluminum alloy. By magnetic rotation, the magnetic developer 6 can be conveyed to the recording area 10 formed between the developing roll 5 and the image carrier 1. The sleeve 9 that constitutes the developing roller 5 is electrically connected to the bias voltage source 11.

Next, reference numeral 12 denotes a charging / cleaning roll, which is constructed similarly to the developing roll 5 and is provided in the vicinity of the developing roll 5 on the upstream side in the moving direction of the image bearing body 1 so as to face the image bearing body 1. That is, a permanent magnet member 13 having a plurality of magnetic poles provided on the surface thereof and a sleeve 14 formed in a hollow cylindrical shape by a non-magnetic material such as an aluminum alloy are coaxially combined to each other, and relative rotation of both members is performed. A charging / cleaning agent 15 composed of a magnetic carrier and a magnetic toner is supplied to the image carrier 1 to form a magnetic brush so that the surface of the image carrier 1 is rubbed. A mesh member 16 is formed of a non-magnetic material such as plastic, is arranged outside the charging / cleaning roll 12, and is a mesh through which only the excess magnetic toner 17 in the charging / cleaning agent 15 passes. A portion 18 (mesh size 40 μm) is provided.

Reference numeral 20 denotes an optical signal irradiating means, which is a recording area 1
It is provided on the back side of the image carrier 1 of No. 0 so that the image carrier 1 can be irradiated with an optical signal corresponding to the original image. Reference numeral 21 denotes a transfer roll, which is formed of a conductive material such as copper or a copper alloy, is electrically connected to the bias voltage source 22, and is provided on the surface of the image carrier 1 so as to be capable of being pressed and rotated. 24
Is a recording member, which can be moved between the image carrier 1 and the transfer roll 21 in the arrow direction, and can be moved to a fixing unit (not shown) provided at the subsequent stage.

With the above structure, the charging / cleaning roll 12
A magnetic brush is formed by the charging / cleaning agent 15 adsorbed on the magnetic brush, and the surface of the image carrier 1 is uniformly charged by the magnetic brush. Further, when the magnetic developer 6 is supplied to the recording area 10 by the developing roll 5, the magnetic developer 6 forms a magnetic brush in the recording area 10, and the magnetic brush comes into sliding contact with the surface of the image carrier 1 with a certain width. Therefore, it is possible to apply a charge or a potential due to frictional charging to the surface of the image carrier 1.

On the other hand, when an optical signal corresponding to the original image is emitted from the back surface of the image carrier 1 via the optical signal irradiating means 20, a portion of the surface of the image carrier 1 which is not irradiated with light and the developing roller 5 are irradiated.
There is no potential difference between the developing roller 5 and the developing roller 5, and the toner in the magnetic developer 6 adheres to that portion and is developed as a toner image. Next, the toner image is transferred to the image carrier 1 and the transfer roll 2.
It is transferred onto the recording member 24 which moves between the recording medium 1 and the recording medium 1 and further fixed by the fixing means.

In the image forming method as described above, as a result of a study by paying attention to the characteristics of the magnetic carrier constituting the cleaning / charging agent 15, as a result of setting the volume resistivity value in a specific range, the image density is reduced. It was revealed that a high-quality image with good resolution was obtained. The results will be described below.

First, a magnetic toner and a magnetic carrier were prepared by blending the following raw materials. Magnetic toner Styrene-n-butyl methacrylate copolymer 49 parts by weight (Mn = 1.6 × 10 ⁴ , Mw = 21 × 10 ⁴ ) Magnetite 45 parts by weight (Toda Kogyo EPT500) Polypropylene 5 parts by weight (Sanyo Kasei VISCOL) 550P) Negatively chargeable charge control agent 1 part by weight (Bontron E-81 manufactured by Orient Chemical Co., Ltd.) The raw materials having the above composition are kneaded with a kneader having a heating roller for 30 minutes, cooled, solidified, pulverized and classified. A negatively chargeable magnetic toner having an average particle size of 10 μm is used.
In a hot air stream of 0 ° C., 0.5 part by weight of hydrophobic silica (R972 manufactured by Nippon Aerosil Co., Ltd.) was added to 100 parts by weight of the magnetic toner and uniformly fixed on the surface of the magnetic toner. The volume resistivity of this magnetic toner is 10 ¹⁴ Ω · c.
m, and the triboelectric charge amount was -15 μc / g.

The value of the volume resistivity is 0.1 kg after weighing an appropriate amount of sample (tens of mg) and filling it in a Teflon (trade name) cylinder with an inner diameter of 3.05 mm with an improved dial gauge. Under the load of D. C. An electric field of 100 V / cm was applied and measured, and the resistance value was calculated. A Yokogawa Hewlett-Packard Model 4329 Insulation Resistance Tester was used to measure the resistance. For the triboelectric charge amount, first, a developer prepared to have a toner concentration of 5% by weight was mixed well, and the blow pressure was 1.0 k
The toner was blown at gf / cm ² , and this was measured by a blow-off powder charge amount measuring device (TB-200 type manufactured by Toshiba Chemical).

Magnetic Carrier Ba—Ni—Zn Ferrite Carrier (Made by Hitachi Metals
100 parts by weight of KBN-100) and 3 parts by weight of a silicone resin are mixed, and the mixture is mixed with a fluidized bed type coating device to give 17
Heat treatment was performed at 0 ° C. for 30 minutes, and after crushing, classification was performed to obtain a resin-coated magnetic carrier having an average particle size of 50 μm. Thereafter, 2 parts by weight of carbon black (# 44 manufactured by Mitsubishi Kasei) was externally added to the surface of the coating layer. The volume resistivity of this magnetic carrier is 5 ×
It was 10 ⁴ Ω · cm.

The above magnetic toner and magnetic carrier were mixed to form a cleaning / cleaning agent having a toner concentration of 30% by weight. The toner concentration of the cleaning / charging agent is preferably 20 to 80% by weight.

Next, the magnetic developer is the following magnetic toner and B
a-Ni-Zn ferrite carrier (Kitachi K
BN-100, average particle size 70 μm, no resin coating layer, volume specific resistance 10 ⁹ Ω · cm) and toner concentration 4
It was set to 0% by weight. The toner concentration in the magnetic developer is 10
It is preferably about 95% by weight.

Next, the charging, developing, transfer and fixing conditions will be described. First, the doctor gap that regulates the layer thickness of the charging / cleaning agent 15 on the charging / cleaning roll 12 is set to 0.3 m.
m, and the charging gap with the image carrier 1 is 0.5 mm.
And The charging / cleaning roll 12 has a permanent magnet member 13 with 8 poles magnetized inside a sleeve 14 made of SUS304 and having an outer diameter of 20 mm. The surface magnetic flux density on the sleeve 14 is 700 G and the rotation speed of the sleeve 14 is 150 r. p.
m. And

The doctor gap for regulating the layer thickness of the magnetic developer 6 on the developing roll 5 is 0.25 mm, and the developing gap in the recording area 10 is 0.4 mm. The specifications of the permanent magnet member 8 and the sleeve 9 constituting the developing roll 5 were the same as those of the charging / cleaning roll 12.

Next, the image carrier 1 was formed of a negatively chargeable photo-semiconductor to have a diameter of 40 mm and a peripheral speed of 50 mm / sec. On the other hand, a bias voltage of −350 V was applied to the sleeve 9 of the developing roll 5. The fixing means after the transfer was heat roll fixing, and the fixing temperature was 190 ° C. and the linear pressure was 1 kg / cm.

Under the above conditions, the surface of the image carrier 1 is-
Table 1 shows the results of image formation by charging to 450V.
In the comparative example in Table 1, the magnetic carrier forming the charging / cleaning agent 15 was the same as the magnetic carrier forming the developer 6.

[0045]

[Table 1]

As is apparent from Table 1, in the comparative example, the image density and the resolution are low, the cleaning action of the residual toner after transfer is insufficient, and the fog is large. On the other hand, in the case of the present invention, the cleaning action of the charging / cleaning agent 15 is good, and the residual toner on the surface of the image carrier 1 is effectively collected by the magnetic brush formed by the charging / cleaning agent 15. It can be seen that fog can be significantly reduced. The residual toner collected from the surface of the image carrier 1 passes through the mesh portion 18 of the mesh member 16 provided outside the charging / cleaning roll 12, and as shown by the reference numeral 17, in the vicinity of the developing roll 5. Is supplied to.

[0047]

Since the present invention has the constitution and operation as described above, the image bearing member can be charged by the charging / cleaning means composed of the magnetic brush, and the residual toner can be effectively collected, and the corona is generated. There is no occurrence of things,
In addition, the image density and resolution are large, and it is possible to form a high-quality image without fog.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of essential parts showing an example of an image forming apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 1 image carrier 5 developing roll 12 charging / cleaning roll 21 transfer roll

[Procedure amendment]

[Submission date] May 16, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

Reference numeral 20 denotes an optical signal irradiating means (for example, an LED array).
B), which is provided on the back side of the image carrier 1 in the recording area 10 so that the image carrier 1 can be irradiated with an optical signal corresponding to the original image. Reference numeral 21 denotes a transfer roll, which is formed of a conductive material such as copper or a copper alloy, is electrically connected to the bias voltage source 22, and is provided on the surface of the image carrier 1 so as to be capable of being pressed and rotated. A recording member 24 is movable between the image carrier 1 and the transfer roll 21 in the arrow direction,
It is possible to travel to a fixing unit (not shown) provided in the subsequent stage.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

The value of the volume resistivity is 0.1 kg after weighing an appropriate amount of sample (tens of mg) and filling it in a Teflon (trade name) cylinder with an inner diameter of 3.05 mm with an improved dial gauge. Under the load of D. C.
An electric field of 100 V / cm and D.I. C.
An electric field of 4000 V / cm was applied and measured, and the resistance value was calculated. A Yokogawa Hewlett-Packard Model 4329 Insulation Resistance Tester was used to measure the resistance. The triboelectric charge is
First, a developer prepared to have a toner concentration of 5% by weight is mixed well, the toner is blown at a blow pressure of 1.0 kgf / cm ² , and this is measured with a blow-off powder charge meter (TB-200 manufactured by Toshiba Chemical). did.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0039

[Correction method] Change

[Correction content]

The above magnetic toner and magnetic carrier were mixed to prepare a cleaning / charging agent . The toner concentration of the cleaning / charging agent is preferably 20 to 80% by weight.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadashi Kodama 1-3-1 Gotenyama, Musashino City, Tokyo NTT Advanced Technology Co., Ltd. (72) Inventor Yasuo Nosue Gotenyama, Musashino City, Tokyo 1-31 NTT Advanced Technology Co., Ltd. (72) Inventor Yoshihiro Noguchi 1-3-3 Gotenyama, Musashino City, Tokyo NTT Advanced Technology Co., Ltd. (72) Inventor Yoshiko Meguro 1-31 Gotenyama, Musashino City, Tokyo NTT Advance Technology Co., Ltd.

Claims (1)

[Claims] 1. An image carrier made of a light-transmitting optical semiconductor material is movably provided, and a permanent magnet member having a plurality of magnetic poles on its surface is built in a hollow cylindrical sleeve made of a non-magnetic material. The developing roll is provided so as to face the surface of the image carrier, and the magnetic carrier supplied on the sleeve is composed of a triboelectrically-charged magnetic toner having an insulating property and a magnetic developer is provided between the sleeve and the permanent magnet member. The magnetic developer is transferred to the recording area formed between the sleeve and the image carrier by rotation, and the optical signal corresponding to the original image is applied to the recording area from the back surface of the image carrier to thereby apply the magnetic developer to the surface of the image carrier. In the image forming method in which the magnetic toner in the inside is selectively adhered and the obtained toner image is transferred onto the recording member via the roller type transfer means, in the upstream side in the moving direction of the image carrier near the developing roll, The charging and cleaning roller to components a permanent magnet member having a plurality of magnetic poles by the image bearing member and the counter rotatably provided,
The surface of this charging / cleaning roll has a volume resistivity of 10 ⁵ Ω.
A magnetic brush having a size of less than 1 cm and a cleaning agent composed of the magnetic toner is adhered to form a magnetic brush, and the magnetic brush is rubbed against the surface of the image carrier to charge the surface of the image carrier and residual toner. After the cleaning and recovery are performed, the image is formed by the developing roll, and the non-magnetic toner is disposed outside the charging / cleaning roll so that only the excess magnetic toner in the charging / cleaning agent passes through. An image forming method characterized in that the surplus magnetic toner is supplied to the developing roll through a mesh member made of a magnetic material.