JPH0683116A - Developing method - Google Patents

Abstract

PURPOSE:To realize a developing method by which excellent image quality is obtained even in the case of using a plain paper by simple constitution. CONSTITUTION:In a back exposing system developing method, a negatively charged image carrier 1 and magnetic developer 6 obtained by mixing negatively charged toner with positively charged magnetic particles are used, or the positively charged image carrier 1 and the magnetic developer 6 obtained by mixing the positively charged toner with the negatively charged magnetic particles are used; and the volume specific resistances of the toner and the magnetic particles are set >=10<12>OMEGA.cm, and >10<5>OMEGA.cm-<=10<12>OMEGA.cm, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic developer which is irradiated with an optical signal from the back of an image carrier made of an optical semiconductor material having a light-transmitting property and conveyed by a developing roll composed of a permanent magnet member and a sleeve. The present invention relates to a developing method for selectively adhering toner therein.

[0002]

2. Description of the Related Art Conventionally, as means for reproducing information such as documents or figures, means such as electrophotography, electrostatic recording or electrostatic printing have been generally used. For example, in an electrophotographic copying machine or a facsimile, after a latent electrostatic image is formed on a photoconductive layer or a dielectric layer, toner charged to a predetermined polarity by frictional charging with a carrier by a magnetic brush method, Alternatively, an image forming method is often employed in which a magnetic toner containing a binder resin and magnetic powder as main components is selectively attached to the latent image to obtain a reproduced image. However, when such an image forming method is adopted, an electrostatic latent image forming unit including a charging unit for uniformly uniformly charging the image carrier in advance is provided separately from the developing unit 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, US Pat. No. 3,816,840, 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, all of them are designed to pass the recording member 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, and at the same time, increase the speed. 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 a light-transmitting optical semiconductor material,
An image in which conductive magnetic toner conveyed by a developing roll composed of a permanent magnet member and a sleeve is selectively attached to the surface of an image carrier for development, and the reproduced image is transferred and fixed on the surface of the recording member. Forming methods have also been proposed.

[0006]

The above-mentioned rear exposure method
In the image forming method, the volume resistivity is, for example, 10
^Four-10¹²The so-called medium resistance magnetic toner of Ω · cm is used.
Although the developability is good, the transfer efficiency of the reproduced image is high.
There is a problem that is low. That is,
Even when using the corotron method, which is also common
Is not completely transferred to the surface of the recording member, causing so-called transfer blur.
Occurs and the image quality deteriorates. Therefore, it is usually used as a recording member.
It has the drawback of not being able to use paper.

On the other hand, it may be possible to uniformly charge the recording member in advance in order to improve the transfer efficiency. However, since this complicates the image forming apparatus, the compactness which has been recently demanded for this type of apparatus, It is not preferable because it cannot meet the needs of price reduction. It should be noted that the means of using recording paper which has been surface-treated in advance in order to improve the transfer efficiency leads to an increase in the paper cost and is unsuitable for this kind of apparatus for processing and recording a large amount of information. Therefore, even when plain paper is used, the development of a developing method that has a high transfer efficiency and is capable of forming a high quality reproduced image is desired.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problems existing in the above-mentioned prior art, and to provide a developing method having a simple structure and capable of obtaining a reproduced image of good quality even when plain paper is used. To do.

[0009]

In order to achieve the above object, in the first invention, an image carrier made of a light-transmitting optical semiconductor material is movably provided and a plurality of magnetic poles are provided on the surface. A hollow cylindrical sleeve made of a non-magnetic material is provided so as to face the surface of the image carrier, and the magnetic developer supplied onto the sleeve is provided between the sleeve and the permanent magnet member. It is conveyed to the recording area formed between the sleeve and the image carrier by static rotation,
In the developing method in which the toner in the magnetic developer is selectively adhered to the surface of the image carrier by irradiating the recording area with an optical signal corresponding to the original image from the back surface of the image carrier, the image formed to be negatively charged Carrier and volume resistivity 10 ¹² Ω · cm
As described above, the negatively chargeable toner formed to have an average particle size of 5 to 20 μm and the volume specific resistance are larger than 10 ⁵ Ω · cm and 10
Magnetic properties obtained by mixing positively charged magnetic particles formed with an average particle size of ¹² Ω · cm or less and an average particle size of 10 to 100 μm or negatively charged magnetic particles whose absolute value of the triboelectric charge amount is smaller than that of the toner. The technical means of using a developer was adopted.

Next, in the second invention, an image carrier made of an optical semiconductor material having a light-transmitting property is movably provided, and a permanent magnet member having a plurality of magnetic poles provided on its surface is incorporated and a non-magnetic material is used. A sleeve formed in a hollow cylindrical shape is provided so as to face the surface of the image carrier, and the magnetic developer supplied onto the sleeve is provided between the sleeve and the image carrier by relative rotation of the sleeve and the permanent magnet member. A developing method in which the toner in the magnetic developer is selectively adhered to the surface of the image carrier by transporting it to the formed recording region and irradiating the recording region with an optical signal corresponding to the original image from the back surface of the image carrier. , The image carrier formed to be positively charged and the volume resistivity 1
0 ¹² Ω · cm or more, positively chargeable toner formed to have an average particle size of 5 to 20 μm and volume resistivity of more than 10 ⁵ Ω · cm and 10 ¹² Ω · cm or less, average particle size of 10 to 100 μm.
The technical means of using the magnetic developer formed by mixing the negatively chargeable magnetic particles or the positively chargeable magnetic particles having a triboelectric charge amount smaller than that of the toner formed in m is used. .

The average particle size of the negatively chargeable toner or the positively chargeable toner constituting the magnetic developer used in the above invention is 5 to 20 μm, preferably 6 to 16 μm, but the particle size is small. If it 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.

Next, the positively chargeable magnetic particles in the first invention or the negatively chargeable magnetic particles in which the absolute value of the triboelectric charge amount is smaller than that of the toner, and the negatively chargeable magnetic particles in the second invention. Alternatively, the average particle size of the positively chargeable magnetic particles having a triboelectric charge amount smaller than that of the toner is 10 to 10
The particle size is 0 .mu.m, preferably 20 to 50 .mu.m, and has a particle size larger than that of the positively chargeable toner. If the particle size is small, it tends to adhere to the image carrier, which is not preferable. On the other hand, when the particle size is large, it is necessary to more strictly control the toner density when using a magnetic developer, and the surface of the image carrier tends to be damaged, which is a disadvantage.

Further, if the volume resistivity of the negatively chargeable toner or the positively chargeable toner is less than 10 ¹² Ω · cm, the transferability is deteriorated, which is not preferable. On the other hand, the volume specific resistance of the positively chargeable magnetic particles or the negatively chargeable magnetic particles in which the absolute value of the triboelectric charge amount is smaller than that of the toner in the first invention, or the negatively chargeable magnetic particles in the second invention. Is more than 10 ¹² Ω · cm, the electric field of the carrier chain formed on the sleeve is increased by the magnetic field of the permanent magnet member, the bias voltage is less likely to be applied, and the developability is deteriorated, which is inconvenient. If the volume resistivity of the magnetic particles is 10 ⁵ Ω · cm or less,
It is not preferable because it is difficult to charge the toner. Therefore, the preferable range of the volume resistivity of the magnetic particles is 2 × 10 ⁵ to
9 × 10 ¹¹ Ω · cm (more preferably 1 × 10 ⁶ to 1 ×
10 ¹¹ Ω · cm).

In order to obtain the volume resistivity value as described above, it is desirable to contain 0.2 to 20% by weight of conductive particles such as conductive ceramic powder or carbon powder. The conductive particles can be added internally and / or externally to the magnetic particles.

Next, as the binder resin constituting the toner, the following ones can be used. When the fixing method is a heat fixing method (oven or hot roll), for example, the following thermoplastic resins, that is, styrenes, vinyl esters, α-methylene aliphatic monocarboxylic acid esters, acrylonitrile, methacryloyl are used. A homopolymer obtained by polymerizing monomers such as nitrile, acrylamide, vinyl ethers, vinyl ketones, and N-vinyl compounds, a copolymer obtained by copolymerizing two or more kinds of these monomers, or a mixture thereof is used. Can be used. In addition, 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, a polyester resin or the like and the vinyl type resin as described above. Can be used.

Next, when the fixing method is the pressure fixing method, 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 phenol resin, natural resin modified phenol resin, amino resin, silicone resin, urea resin, acrylic acid or methacrylic acid and long chain alkyl methacrylate, copolymer oligomer of long chain alkyl acrylate, polyolefin, ethylene vinyl acetate copolymer Examples thereof include polymer, ethylene / vinyl alkyl ether copolymer, and maleic anhydride copolymer.

These resins can be arbitrarily selected and mixed and used, 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 used. Is effective.

The toner in the magnetic developer used in the present invention is not only a non-magnetic toner, but also a magnetic powder made of a compound or alloy containing iron, cobalt, nickel or another ferromagnetism element such as ferrite or magnetite. A magnetic toner containing is also usable. The above magnetic powder has an average particle size of 0.01-
It is desirable to form it to 3 μm. The content may be in the range of 30 to 95% by weight (preferably 30 to 75% by weight).

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 deteriorate the fixing property. It is good to say

The above 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. Conductive particles may be externally added to the surface of the toner particles, and the conductive particles may be fixed by heat treatment, or the conductive particles may be internally added in the heating and kneading step. Good.

Next, as the magnetic particles constituting the magnetic developer, not only the particles made of the ferromagnetic material as described above,
A dispersion of these particles in a binder resin can also be used, but magnetite or ferrite particles are most suitable. The magnetic particles may be used as they are, but it is effective to provide a coating layer made of a resin material on the surface of the magnetic particles.

The resin material forming the coating layer is
In the first invention, a simple substance such as a silicone resin, a styrene-acrylic resin, a polyester resin, a maleic acid resin and an acrylic acid resin, a copolymer, a modified product and the like can be mentioned. 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.

Next, in the second invention, the resin material forming the coating layer is preferably a resin material containing a fluororesin containing a hydrophilic functional group such as a carboxyl group and / or a hydroxyl group as a main component. The fluororesin includes tetrafluoroethylene, polyvinylidene fluoride, polyvinyl fluoride, fluoroethylene propylene copolymer, ethylene tetrafluoroethylene copolymer, polychlorotrifluoroethylene, ethylene chlorotrifluoroethylene copolymer, fluoroethylene. Copolymers and the like are known, and these fluororesins contain carboxyl groups,
It is preferable to use a resin into which a hydrophilic functional group such as a hydroxyl group, an amino group or an epoxy group has been introduced.

A hardener may be used in combination to firmly fix the fluororesin containing the hydrophilic functional group on 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 adhesion 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 phenolic resin, urea resin, alkyd resin, other fillers, diluents, flexibility-imparting agents, etc. can be blended for the purpose of controlling toner chargeability and imparting fluidity to the developer. .

[0026]

FIG. 1 is a cross-sectional explanatory view of essential parts showing an example of a developing device used in the developing method of the present invention. In FIG. 1, reference numeral 1 denotes an image carrier, for example, a conductive layer 3 having a light-transmitting property and an organic optical semiconductor material having a light-transmitting property, or a on a surface of a support 2 made of a light-transmitting material such as glass. A photosensitive layer 4 made of a SiH film is applied to form a hollow cylinder, and is provided so as to be rotatable clockwise, for example. The photosensitive layer 4
A protective layer made of a wear resistant material may be provided on the surface of the.

A developing roll 5 is provided at the end of a developer tank 7 containing the 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 sleeve 9 formed in a hollow cylindrical shape with 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, 12 is an optical signal irradiating means, which is provided on the back side of the image carrier 1 in the recording area 10 so as to irradiate the image carrier 1 with an optical signal corresponding to the original image. A transfer device 13 is provided in the vicinity of the surface of the image carrier 1. 14
Is a recording member, which can be moved in the direction of the arrow and can be moved to a fixing unit (not shown) provided at the subsequent stage.

With the above construction, when the magnetic developer 6 is supplied to the recording area 10 by the developing roll 5, the magnetic developer 6
Forms a so-called magnetic brush in the recording area 10, and this magnetic brush makes 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. Alternatively, a charging means such as a scorotron or a charging brush may be provided before development in order to stabilize the charge amount.

On the other hand, when an optical signal corresponding to the original image is irradiated from the back surface of the image carrier 1 through the optical signal irradiation means 12, 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, this toner image is transferred onto the recording member 14 which moves between the image carrier 1 and the transfer device 13, and is further fixed by the fixing means.

[0031]

[Examples] In the developing method as described above, as a result of an examination focusing on the characteristics of the toner and the magnetic particles constituting the magnetic developer, it was found that the image density can be improved by setting the value of volume resistivity to a specific range. It was revealed that a high-quality image with good resolution was obtained. The results will be described below.

First, by mixing the following raw materials, a magnetic toner (A1) and a non-magnetic toner (A2) having a negative charging property,
Further, magnetic particles (B1) having a positive charging property and magnetic particles (B2) and (B3) having a negative charging property were produced.

(A1) Negatively Chargeable Magnetic Toner Styrene-n-butyl methacrylate copolymer 32 parts by weight (Mn = 1.6 × 10 ⁴ , Mw = 21 × 10 ⁴ ) Magnetite 60 parts by weight (Toda Kogyo EPT500) Polypropylene 5 parts by weight (Viscole TP32 manufactured by Sanyo Kasei) Negative charging control agent 3 parts 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 and solidified. After that, pulverization and classification are performed to obtain a negatively chargeable magnetic toner having an average particle size of 9 μm, and further 120
0.6 parts by weight of hydrophobic silica (manufactured by Nippon Aerosil Co., Ltd.) with respect to 100 parts by weight of this magnetic toner in a hot air flow of ℃
Aerosil R972) was added and uniformly fixed on the surface of the magnetic toner.

(A2) Negatively chargeable non-magnetic toner Styrene-n-butyl methacrylate copolymer 80 parts by weight (Mn = 1.6 × 10 ⁴ , Mw = 21 × 10 ⁴ ) Polypropylene 5 parts by weight (Viscole manufactured by Sanyo Kasei Co., Ltd.) TP32) Negatively chargeable charge control agent 3 parts by weight (Bontron E-81 manufactured by Orient Chemical Co., Ltd.) 5 parts by weight filler (CaCO ₃ ) (average particle size 0.9 μm manufactured by Nitto Koka Kogyo Co., Ltd.) 7 parts by weight carbon black (colorant) (# 44 manufactured by Mitsubishi Kasei) The above-mentioned blended raw materials were produced by the same means as in (A1) above.

(B1) Positively Chargeable Magnetic Particles Styrene-n-butylmethacrylate copolymer 30 parts by weight (Mn = 1.6 × 10 ⁴ , Mw = 21 × 10 ⁴ ) Magnetite 60 parts by weight (EPT500 manufactured by Toda Kogyo Co., Ltd.) Polypropylene 5 parts by weight (Sanyo Chemical Co., Ltd. Viscole 550P) Positively chargeable charge control agent 3 parts by weight (Orient Chemical oil black BY) Carbon black 2 parts by weight (Mitsubishi Kasei # 44) The above ingredients have a heating roller. After kneading with a kneader for 30 minutes, cooling and solidifying, crushing and classification to obtain positively charged magnetic particles with an average particle size of 30 μm, and further 120
1.0 part by weight of carbon black (Mitsubishi Kasei # 4
4) was added and uniformly fixed on the surface of the magnetic particles.

(B2), (B3), (B4) Negatively charged magnetic particles Ba-Ni-Zn ferrite carrier 100 parts by weight (KBN-100 made by Hitachi Metals) Resin silicone resin 3 parts by weight (SR-made by Toray Silicone) 2410) Using the fluidized bed coating device with the above composition,
Heat treatment at 0 ° C for 30 minutes, classify after crushing, 10-5
A resin-coated carrier of 0 μm was obtained. After that, 0.5 parts by weight of carbon black (# 44 manufactured by Mitsubishi Kasei) was coated on the surface of the coating layer to form B2 magnetic particles, and 0.3 parts by weight of carbon black (same as above) was coated to form B3 magnetic particles. (Same as above) was coated with 0.8 part by weight to obtain B4 magnetic particles.

The negatively chargeable toner prepared as described above and magnetic particles are mixed to give a toner concentration of 40% (toner: A
1) and 5% (toner: A2) of the magnetic developer were used, and the results of development under the conditions described below are shown in Table 1. Table 1
For the volume resistivity values of the negatively chargeable toner and magnetic particles shown in Fig. 3, weigh an appropriate amount (10 mg) of the sample and fill it in a Teflon (trade name) cylinder with an improved dial gauge and an inner diameter of 3.05 mm. Under a load of 0.1 kg. C. 10V
The measurement was performed by applying an electric field of / cm, and the resistance value was calculated. A Yokogawa Hewlett-Packard Model 4329 Insulation Resistance Tester was used to measure the resistance.

Next, the developing, transferring and fixing conditions will be described. First, the doctor gap that regulates the layer thickness of the magnetic developer 6 on the developing roll 5 is set to 0.3 mm, and the recording area 10
The development gap of No. 2 was set to 0.25 mm. Next, developing roll 5
Is a SUS304 sleeve 9 having an outer diameter of 20 mm, in which a permanent magnet member 8 magnetized with 8 poles is incorporated, the surface magnetic flux density on the sleeve 9 is 700 G, and the rotation speed of the sleeve 9 is 1
It was set to 50 rpm.

The image carrier 1 was formed of a negatively chargeable organic 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. The fixing temperature in the fixing means after transfer is 190
° C, linear pressure 1kg / cm. The triboelectric charge amount of the toner in Table 1 below is obtained by thoroughly mixing the developer prepared to have a toner concentration of 5% by weight and blowing the toner at a blow pressure of 1.0 kgf / cm ² , which is the blow-off powder charge amount. It measured with the measuring device (Toshiba Chemical make TB-200 type).

[0040]

[Table 1]

As is clear from Table 1, a good image was obtained by combining the high resistance toner and the low resistance magnetic particles (carrier). The magnetic particles used as carriers had no spent, and stable images were obtained even during continuous copying.

Next, by mixing the following raw materials, a magnetic toner (A10) and a non-magnetic toner (A2) having a positive charging property are obtained.
0), and magnetic particles (B10) having a negative charging property,
(B20) and (B30) were produced.

(A10) Positively chargeable magnetic toner Styrene-n-butyl methacrylate copolymer 32 parts by weight (Mn = 1.6 × 10 ⁴ , Mw = 21 × 10 ⁴ ) Magnetite 60 parts by weight (Toda Kogyo EPT500) Polypropylene 5 parts by weight (NP505 manufactured by Mitsui Petrochemical Co., Ltd.) Positively chargeable charge control agent 3 parts by weight (Oil Black BY 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 and solidified , Pulverize and classify to obtain a positively chargeable magnetic toner having an average particle size of 10 μm.
In a hot air stream of 0 ° C., 0.6 part by weight of hydrophobic silica (Aerosil 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.

(A20) Positively chargeable non-magnetic toner Styrene-n-butylmethacrylate copolymer 80 parts by weight (Mn = 1.6 × 10 ⁴ , Mw = 21 × 10 ⁴ ) Polypropylene 5 parts by weight (Viscole manufactured by Sanyo Kasei Co., Ltd.) 550P) Positively chargeable charge control agent 3 parts by weight (Bontron N-01 manufactured by Orient Chemical Co., Ltd.) 5 parts by weight of filler (CaCO ₃ ) (average particle size 0.9 μm manufactured by Nitto Koka Kogyo) 7 parts by weight of carbon black (colorant) Part (Mitsubishi Chemical's # 44) The above compounded raw materials were produced by the same means as in (A10) above.

(B10) Negatively Chargeable Magnetic Particles Styrene-n-butylmethacrylate copolymer 30 parts by weight (Mn = 1.6 × 10 ⁴ , Mw = 21 × 10 ⁴ ) Magnetite 60 parts by weight (Toda Kogyo EPT500) Polypropylene 5 parts by weight (Sanyo Kasei VISCOL 550P) Negative charge control agent 3 parts by weight (Orient Chemical Co., Bontron E-81) Carbon black 2 parts by weight (Mitsubishi Kasei # 44) After kneading for 30 minutes with the kneader, cooling and solidifying, pulverizing and classifying to obtain negatively charged magnetic particles having an average particle size of 40 μm, and further 120
1.5 parts by weight of carbon black (# 4 manufactured by Mitsubishi Kasei)
4) was added and uniformly fixed on the surface of the magnetic particles.

(B20), (B30) Negatively chargeable magnetic particles Ba-Ni-Zn ferrite carrier 100 parts by weight (KBN-100 manufactured by Hitachi Metals) Resin * (HM-40 manufactured by Hitachi Metals) 3 parts by weight Curing agent ( Melamine-formalin) 0.1 parts by weight * A mixture of 30% by weight of polyvinyl fluoride modified with a carboxyl group (acid value of 20) and 70% by weight of styrene-acrylic resin. Use 17
Heat treatment at 0 ℃ for 30 minutes, classify after crushing, 10-50
A resin-coated carrier of μm was obtained. B20 uses the above ferrite carrier as it is, and B30 uses carbon black (# 44 manufactured by Mitsubishi Kasei) as the resin coated carrier.
Was coated with 0.5% by weight.

The positively charged toner and negatively charged magnetic particles prepared as described above are mixed to obtain a magnetic developer having a toner concentration of 20% (toner: A10) and 5% (toner: A20). The results of development under the conditions are shown in Table 2. The volume resistivity values of the positively chargeable toner and the negatively chargeable magnetic particles shown in Table 2 were measured under the same conditions as in the above examples.

Next, the developing, transferring and fixing conditions will be described. First, the doctor gap for regulating the layer thickness of the magnetic developer 6 on the developing roll 5 was set to 0.3 mm, and the developing gap of the recording area 10 was set to 0.25 mm. Next, the developing roll 5
8 inside a sleeve 9 of SUS304 with an outer diameter of 20 mm
The permanent magnet member 8 magnetized with poles is built in, the surface magnetic flux density on the sleeve 9 is 700 G, and the rotation speed of the sleeve 9 is 150 r.
It was pm.

The image carrier 1 was formed of a positively chargeable organic 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. The fixing temperature in the fixing means after transfer was 190 ° C. and the linear pressure was 1 kg / cm.

[0050]

[Table 2]

As is clear from Table 2, good images were obtained by using the high resistance toner and the low resistance magnetic particles (carriers). The carrier did not adhere to the image carrier 1 and the printing durability was good. On the other hand, with regard to transfer, although the transfer efficiency was slightly reduced, it was possible to obtain an image with a similar image density to that before transfer.

In the above-mentioned embodiment, an example in which carbon black is used as the conductive particles to be added to the magnetic particles has been described, but other conductive particles such as metal powder of Ni, Al, etc. are used. Alternatively, the magnetic particles may be internally added, or the internal addition and the external addition may be used together. The toner concentration in the magnetic developer is preferably 2 to 95% by weight. In this case, the toner concentration is preferably 2 to 9% by weight (more preferably 3 to 7% by weight) when the non-magnetic toner is used, and 10 when the magnetic toner is used.
It is preferably 90 to 90% by weight (more preferably 10 to 40% by weight, further preferably 15 to 30% by weight). The image carrier is preferably formed in a hollow cylindrical shape, but may be formed in a belt shape capable of endless movement and suspended between pulleys made of a conductive material. Further, auxiliary uniform charging means may be provided in the vicinity of the image carrier.

[0053]

Since the present invention has the structure and operation as described above, a high-quality image with a large image density and resolution and no fog even when plain paper is used with a simple structure. The effect is that it can be formed.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of essential parts showing an example of a developing device used in a developing method of the present invention.

[Explanation of symbols]

 1 image carrier 5 developing roll 12 optical signal irradiation means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03G 15/09 Z

Claims (2)

[Claims] 1. An image carrier made of an optical semiconductor material having a light-transmitting property is movably provided, a permanent magnet member having a plurality of magnetic poles provided on the surface thereof is built in, and a non-magnetic material is formed into a hollow cylindrical shape. A sleeve is provided so as to face the surface of the image carrier, and the magnetic developer supplied onto the sleeve is conveyed to a recording area formed between the sleeve and the image carrier by relative rotation of the sleeve and the permanent magnet member. Then, in the developing method in which the toner in the magnetic developer is selectively adhered to the surface of the image carrier by irradiating the recording area with an optical signal corresponding to the original image from the back surface of the image carrier, it is formed to be negatively charged. Image carrier, a volume resistivity of 10 ¹² Ω · cm or more, a negatively chargeable toner formed to have an average particle size of 5 to 20 μm, and a volume resistivity of more than 10 ⁵ Ω · cm and 10 ¹² Ω · cm or less. , Average particle size 10 A magnetic developer formed by mixing positively-charged magnetic particles or negatively-charged magnetic particles having an absolute value of triboelectric charge amount smaller than that of the toner formed to a size of 00 μm is used. Development method. 2. An image carrier made of an optical semiconductor material having a light-transmitting property is movably provided, and a permanent magnet member having a plurality of magnetic poles provided on the surface thereof is incorporated and formed into a hollow cylindrical shape with a non-magnetic material. A sleeve is provided so as to face the surface of the image carrier, and the magnetic developer supplied onto the sleeve is conveyed to a recording area formed between the sleeve and the image carrier by relative rotation of the sleeve and the permanent magnet member. Then, in the developing method in which the toner in the magnetic developer is selectively adhered to the surface of the image carrier by irradiating the recording area from the back surface of the image carrier with an optical signal corresponding to the original image, a positive charge property is formed. Image carrier, a volume resistivity of 10 ¹² Ω · cm or more, a positively chargeable toner having an average particle size of 5 to 20 μm, and a volume resistivity of more than 10 ⁵ Ω · cm and 10 ¹² Ω · cm or less. , Average particle size 10 Formed in 00Myuemu, a developing method in which magnetic particles or the friction charge amount of negative charging property is characterized by the use of a magnetic developer comprising a mixture of a positively chargeable magnetic particles is smaller than that of the toner.