JPH073610B2 - High-speed development method for amorphous silicon photoconductive layer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high-speed development method for an amorphous silicon photoconductive layer, and more specifically, to an amorphous silicon photoconductive layer. , A developing method for producing a copy having a high density and high quality image at a high speed.

(Prior Art) In electrophotography using a two-component magnetic developer, a sensible toner and a magnetic carrier are mixed, and the two-component composition is supplied onto a developing sleeve having a magnet inside. Then, a magnetic brush made of this composition is formed, and the electrophotographic photosensitive plate having an electrostatic latent image is rubbed against the magnetic brush to form an electrophotographic toner image on the photosensitive plate. The electrostatic toner is charged with a charge having a polarity opposite to that of the electrostatic latent image on the photosensitive plate due to friction with the magnetic carrier, and the electrostatic toner particles on the magnetic brush are transferred onto the electrostatic latent image by Coulomb force. And the electrostatic latent image is developed. On the other hand, the magnetic carrier is attracted by the magnet in the sleeve,
Moreover, the charged charge has the same polarity as the charge of the electrostatic latent image,
Therefore, the magnetic carrier remains on the sleeve. In order to form a clear and high-density image, provide a sufficient relative speed difference between the photosensitive plate and the magnetic brush so that the photosensitive plate is sufficiently rubbed by the magnetic brush. is important.

In recent years, it has been proposed to use ferrite, particularly soft ferrite, as a magnetic carrier for a two-component developer. However, in connection with the fact that the ferrite carrier has a higher electric resistance than the iron powder carrier, there is a problem that the carrier is pulled during development, that is, the carrier moves to the photosensitive layer side, and an edge effect occurs in the formed image. Prone to problems.

As a solution to this problem, Japanese Patent Application Laid-Open No. 59-139056 uses a two-component developer composed of a ferrite carrier and a toner, and the electric resistance (R) of the developer and the clearance between the sleeve and the photoreceptor are used. It has been proposed to develop under the condition that (d) is selected within a certain range.

(Problems to be Solved by the Invention) However, when this developing method is applied to a photoconductor having an amorphous silicon photoconductive layer by high-speed copying, many problems still remain with respect to image quality, image density, and the like. Was found to cause problems.

That is, the amorphous silicon-based photoconductor layer has high surface hardness, is sensitive to light having a long wavelength side, and is also highly sensitive, and thus is expected to be used as a photoreceptor for high-speed copying. When the amorphous silicon photoconductive layer is actually used for high-speed copying, it is greatly restricted not in terms of sensitivity but in terms of developing conditions. For example, if the moving speed of the photoconductor becomes high. It takes a shorter time to pass through the developing area, and the image density tends to decrease. In order to prevent this, if the number of rotations of the magnetic brush is increased and the toner replenishment speed is increased, the tendency to generate brush marks in the image increases. Also,
Since the amorphous silicon photoconductor has a large electrostatic capacity and a large surface charge density as compared with the most commonly used selenium photoconductor, the development conditions described in the above-mentioned prior art. Then, it is unavoidable that the developing current becomes insufficient and the image density is lowered.

Therefore, an object of the present invention is to provide a developing method capable of forming a toner image of high density and excellent quality on an amorphous silicon photoconductive layer under high speed copying conditions.

Another object of the present invention is to combine a combination of a two-component developer consisting of a ferrite carrier having specific electric characteristics and an electro-photographic toner having specific particle size characteristics with an amorphous silicon photoconductor. It is an object of the present invention to provide a method of using and developing under high speed copying conditions.

(Means for Solving the Problems) The present inventors have found that in a high-speed copying method using a combination of a two-component developer containing a ferrite carrier and an amorphous silicon-based photoconductor, high density and high density are obtained. It has been found that development conditions which are completely different from the conventional development conditions are necessary for forming a high quality toner image.

That is, according to the present invention, a mixture of magnetic carrier particles and toner particles that can be charged by friction between the magnetic carrier particles and an electrostatic image is formed on a photoreceptor having an amorphous silicon photoconductive layer. Is supplied onto a developing sleeve having a magnet in a non-magnetic sleeve to form a magnetic brush of the developer. The photoconductive layer and the magnetic brush are connected to the photoreceptor and the sleeve. Rubbing with a bias voltage applied between
In a developing method comprising forming a toner image corresponding to an electrostatic image, the two-component developer has an electric resistance (hereinafter referred to as DS resistance) measured as a magnetic brush between the sleeve and the surface of the photoconductor. Ferrite carrier within the range of 3 × 10 ^{6 to} 5 × 10 ⁷ Ω, median diameter of 5 to 20 μm and grain size of 5
100: 3 to 1 with electrophotographic toner particles having a volume resistance of 1 × 10 ¹³ Ω-cm or more, in which the content of particles having a size of less than μm is substantially zero.
The developer contained in a weight ratio of 00:11, the clearance between the sleeve and the photoreceptor is d (mm), and the electrical resistance measured as a magnetic brush between the sleeve and the photoreceptor surface of the two-component developer is R ( Ω), the following formula 2 × 10 ⁷ ≦ R ≦ 5 × 10 ⁸ (1) Under conditions that satisfy the condition, the moving speed of the photoconductor should be 12 to 27 m / mi.
There is provided a high-speed development method, which is characterized in that the development is performed in the range of n.

In the following description, high-speed development in the present specification means that development is performed with the moving speed of the photoconductor in the range of 12 to 27 m / min.

(Operation) In FIG. 1 for explaining the developing conditions used in the present invention, the area surrounded by four lines 1-a, 1-b, 2a and 3a is the developing area used in the above-mentioned prior art. Is. here,
Line 1-a has R = 5 × 10 ⁹ , line 1-b has R = 1 × 10 ⁸ , and 2a has d = 1.4.
85 × 10 ⁵ / (log R) ^5.3 , line 3a is d = 1.485 × 10 ⁵ / (log
R) Corresponds to ^5.5 respectively.

On the other hand, according to the present invention, in the high-speed development of the amorphous silicon photoconductive layer, it is necessary to select a development area which is independent of the above area and forms a high density and high quality toner image. It is based on the new finding that it is extremely critical to. That is, the developing region used in the present invention is a region below the line 3a and surrounded by the other three lines 4a, 4b and 3b, where the line 4a is R = 5 × 10 ⁸ Ω, Line 4b is R =
2 × 10 ⁷ Ω and line 3b correspond to d = 1.485 × 10 ⁵ / (log R) ^5.7 , respectively.

First, regarding the electric resistance (R) and the development clearance (d) of the developer magnetic brush, when high-speed development is performed on the amorphous silicon photoconductor, in the development by the conventional development area above the line 3a, Sufficient developing current cannot be obtained through the brush, the toner density is lowered, and white spots in the image are likely to occur. In the present invention, by performing development in the region below the line 3a, even when high-speed development is applied to the amorphous silicon photoconductor, charge injection into the toner is increased,
The image density can be remarkably improved.

Further, in the developing method according to the present invention, in the area below the line 3b, the image formed tends to have a significantly poor gradation, and defects such as trailing edge chipping may occur in the image. Become. In the present invention, the charge injection through the magnetic brush is set to an appropriate range by performing development in the region above and to the right of the line 3b, so that the gradation has an appropriate gradation and there is no rear end chipping and sharpness. It is possible to obtain such an image.

It has already been pointed out that the amorphous silicon photoconductor has a large electrostatic capacitance and a large surface charge density as compared with the selenium photoconductor and the like, and thus requires a large developing current.
In other high-speed development, as the developing sleeve rotates at high speed,
There is a problem that the dynamic electric resistance of the magnetic brush increases, and the conventional developing conditions cannot be applied as they are.

In FIG. 1, in the area on the right side of the straight line 4a, white spots occur in the solid portion due to the so-called edge effect, and white spots occur in the halftone boundary portion. In order to prevent this, the resistance of the magnetic brush must be set to the left side of the straight line 4a, that is, R5 × 10 ⁸ Ω, especially R3 × 10 ⁸ Ω.
Is desirable.

Further, in the area on the left side of the straight line 4b, brush marks tend to occur in the formed image. According to the present invention, the resistance of the magnetic brush is set to the right of the straight line 4b, that is, R2.
By setting the resistance to × 10 ⁷ Ω, generation of such brush marks can be effectively prevented. The brush mark is a phenomenon in which a fine white pattern is generated in the toner image in the rubbing direction of the magnetic brush. This is because when toner particles once adhere to the electrostatic latent image, It is considered that this is caused by the leakage of electric charge due to the rubbing and the re-peeling of the toner particles. However, according to the present invention, the occurrence of such brush marks is caused by setting the electric resistance of the magnetic brush within the above range. Is effectively prevented.

Thus, the development area surrounded by one line in FIG.
What is extremely critical with respect to the quality of the image formed appears to be apparent from the fact of the example below, where a significant reduction in image quality is observed at conditions some distance from this area.

In the present invention, in order to apply the high-speed development to the combination of the two-component type developer containing the ferrite carrier and the amorphous silicon photoreceptor, it is essential to perform the development in the development area shown in FIG. Although it is indispensable, a high-density and high-quality image is not formed only by performing development in this development area, and certain restrictions or selections are required for the ferrite carrier and toner used.

First, in order to set the developing conditions in the area surrounded by the lines 4a, 3a, 4b, 3b described above, the ferrite carrier is in the form of a magnetic brush, 3 × 10 ^{6 to} 5 × 10 ⁷ Ω, especially 5 × 10 ⁶ Through 3 × 1
It should have an electrical resistance of 0 ⁷ Ω. That is, if the magnetic brush electric resistance of the ferrite carrier is outside the above range,
The magnetic brush resistance of the developer formed by mixing this with a predetermined amount of toner becomes high or low, and it becomes difficult to set the developing condition in the above range. For example, the generation of brush marks, the decrease of image density, or the formation of image Inconvenience occurs such that the edge effect becomes conspicuous in the displayed image.

Further, it is also extremely important that the electrophotographic toner particles used in the present invention have particle size characteristics such that the content of median diameters of 5 to 20 μm and particle diameters of 5 μm or less is substantially zero.

Heretofore, it has been known to use a sensible toner having a particle size of 5 to 35 μm for a two-component developer.
However, in the toner produced by the known pulverization / classification method, even though the particle diameter is adjusted in the range of 5 to 35 μm, fine particles of 5 μm or less are necessarily mixed,
The content of fine particles of 5 μm or less still reaches 0.5 to 2% by volume.

On the other hand, in the present invention, the median diameter of the toner particles is set in the range of 5 to 20 μm, particularly 10 to 14 μm, and the content of particles having a particle size of 5 μm or less is suppressed to substantially zero. By substantially zero is meant the fact that commercially available particle size analysis techniques, such as the Coulter Counter method, do not detect particles with a size below 5 μm.

Therefore, in the present invention, in order to form a high density image by high speed development on an amorphous silicon photoconductor,
It is extremely critical to make the content of particles having a particle size of 5 μm or less substantially zero.

This criticality becomes apparent with reference to the diagram of FIG. FIG. 2 is a diagram in which the abscissa represents the surface potential of the amorphous silicon photoconductor and the ordinate represents the image density. The plot with ∘ indicates that the content of particles having a particle size of 5 μm or less is 0.8% by volume.
When the toner of No. 2 is used, the plot marked with * shows the case of using the toner of which the content of particles having a particle size of 5 μm or less is substantially zero. Referring to FIG. 2, by using a toner that does not substantially contain particles having a particle size of 5 μm or less,
The fact that a significantly higher density of image formation is possible over a wide surface potential range becomes clear. Such facts
This was first observed in the case of high-speed development of an amorphous silicon photoconductor, and was not observed in the case of a conventional low-speed development selenium photosensitive plate, and was unexpected.

Furthermore, the electric resistance of the toner particles has a significant influence on the transfer of the toner image from the surface of the photosensitive layer to the transfer paper, and when the volume resistance of the toner particles is lower than 1 × 10 ¹³ Ω-cm, the toner particles are transferred at the time of transfer. However, the transfer efficiency of the toner particles is lowered, and the toner image is scattered or the contour is broadened.

DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION In FIG. 3 for explaining an electrophotographic method to which the developing method of the present invention is preferably applied, amorphous silicon is formed on the surface of a metal drum 1 which is driven and rotated. A system photoconductor layer 2 is provided. Around this drum, a main charging corona charger 3; an image exposure mechanism composed of a lamp 4, an original supporting transparent plate 5 and an optical system 6; a developing mechanism 7 having toner; a charge eliminating lamp 8; a toner transfer corona charger 9; A corona charger 10 for paper separation; a cleaning mechanism 11; and a discharge lamp 12 are provided in this order.

First, the photoconductor layer 2 is charged by the corona charger 3 with electric charges of constant polarity. Then, the lamp 4 illuminates the original to be copied, and the light image of the original is passed through the optical system 6 and the photoconductive layer 2
Is exposed to form an electrostatic latent image corresponding to the original image.
This electrostatic latent image is developed with toner by the developing mechanism 7.
The transfer paper 14 is supplied so as to come into contact with the drum surface at the position of the toner transfer charger 9, and a corona charge having the same polarity as the electrostatic image is performed from the back surface of the transfer paper 14 to transfer the toner image to the transfer paper 14. Let The transfer paper 14 on which the toner image is transferred is
The electrostatic charge of the separating corona charger 10 is electrostatically separated from the drum and sent to a processing area such as the fixing mechanism 13.

The residual toner is removed from the photoconductive layer 2 after the toner transfer by the cleaning mechanism 11, and then the residual charge is erased by the entire surface exposure by the static elimination lamp 12.

As the photoconductor amorphous silicon-based photoconductor layer, any known material is used, and for example, amorphous silicon deposited on the substrate by plasma decomposition of silane gas is used.
This may be doped with hydrogen, halogen or the like, and further doped with a group III or group V element of the periodic table such as boron or phosphorus.

The physical properties of a typical amorphous silicon photoconductor are as follows: dark conductivity of 10 ^-12 Ω ^-1 · cm ^-1 , activation energy <0.85 eV,
Photoconductivity> 10 ^-7 Ω ^-1 cm ^-1 , optical bandgap 1.7
˜1.9 eV, the amount of bound hydrogen is 10 to 20 atomic%, and the dielectric constant of the film is in the range of 11.5 to 12.5.

This amorphous silicon photoconductive layer can be positively or negatively charged depending on the doping species, and the voltage applied to the corona charger is generally in the range of 5 to 8 kV.

The present invention provides for the amorphous silicon photoconductor layer to have a thickness of 25 to 28.
It is particularly advantageously applied to a photosensitive plate having a relatively large value of μm and a relatively high charging potential.

Magnetic Carrier In the present invention, as the magnetic carrier, a carrier made of any sintered ferrite particles having a DS resistance in the above-mentioned range and a DS resistance in the developer state in the range specified in FIG. 1 is used. . Ferrite sintered particles are known per se, and known sintered ferrite particles, particularly spherical sintered ferrite particles having a DS resistance within the above range are advantageously used. The composition of ferrite is also known, and is generally called soft ferrite, such as, but not limited to, Zn-based ferrite, Ni-based ferrite, Cn-based ferrite, Mn-based ferrite, Mn-Zn-based ferrite, Mn -Mg type ferrite, Cu-Zn type ferrite, Ni-Zn type ferrite, Mn-Cu-Zn type ferrite and the like can be mentioned. A suitable ferrite is atomic weight percent
And Fe35 to 65%, Cu5 to 15%, Zn5 to 15% and Mn0
To 0.5% Cu-Zn or Cu-Zn-Mn ferrite.

The sintered ferrite particles used generally have an average particle size of 30 to
Those in the 100 micron range, especially in the 35 to 90 micron range are preferred. The above-mentioned DS resistance, that is, the dynamic resistance as a magnetic brush is also influenced by the particle size of the carrier particles, and it is possible to adjust the resistance of the magnetic brush to an arbitrary value by adjusting the particle size of the ferrite carrier. it is obvious.
This is probably because, for example, when the particle size of the ferrite carrier is reduced, the number of contact points in the magnetic brush or between the magnetic brush and the sleeve or the surface of the photosensitive layer increases.

The DS resistance of the sintered ferrite particles can be adjusted by other means, and the resistance can be adjusted to a large range by providing a resin coating layer on the surface of the ferrite particles. Examples of the resin for coating include acrylic resin and acrylic-silicone resin, and the coating amount thereof may be 0.1 to 1.5% by weight, particularly 0.3 to 1.0% by weight, based on ferrite.

Toner As the toner, those satisfying the above-mentioned restrictions are used. Needless to say, the toner particles must be colored toners having a sensible property and a fixing property. A granular composition in which a color pigment, a charge control agent and the like are dispersed in a binder resin is used. As the resin, a thermoplastic resin or a thermosetting resin of an uncured or initial condensation product is used. Suitable examples thereof are vinyl aromatic resins such as polystyrene, acrylic resins, polyvinyl acetal resins, polyester resins, epoxy resins, phenol resins, petroleum resins, olefin resins, etc. in the order of importance. As the pigment, for example, one or more kinds of carbon black, cadmium yellow, molybdenum orange, pyrazolone red, fast violet B, phthalocyanine blue, etc. are used, and as the charge control agent, for example, nigrosine base (CI 50415), oil black. (CI 26150), oil-soluble dyes such as spirone black, metal naphthenates, fatty acid metal soaps, etc. are used as necessary.

In the present invention, the fluidity of the developer is improved by making the content of particles having a particle size of 5 μm or less substantially zero,
Development workability can be improved. If the median diameter of the toner is larger than the above range, the resolving power tends to decrease, and if it is smaller than the above range, the developing workability and the fixability such as offset tend to deteriorate.

In order to make the content of particles having a particle size of 5 μm or less substantially zero, it is sufficient to perform a highly accurate classification operation such as applying the toner obtained by the kneading / pulverization method to two or more classification operations.

Developer As the developer, it is preferable to use a mixing ratio of ferrite carrier and toner in a weight ratio of 100: 3 to 100: 11. This quantity ratio also affects the electric resistance of the magnetic brush of the developer. That is, when the ferrite carrier amount ratio increases,
The magnetic brush of the developer tends to have low electric resistance. The optimum ratio of the two is closely related to the specific surface area of the ferrite carrier and the electrophotographic toner. In a preferred embodiment of the invention, the toner concentration (Ct
%) Is the following formula In the formula, Sc is the specific surface area of the ferrite carrier (cm ² / g: the measured value by the permeation method), St is the specific surface area of the toner (cm ² / g: the average particle size measured using a Coulter counter, and the toner is Is the effective specific surface area calculated assuming that is a true sphere, the radius obtained from the average particle size is r (cm), and the true specific gravity of the toner is ρ (g / cm ³ ), St = 3 / (value calculated by r.rho.), and k is a number from 0.80 to 1.07.

First, the term Sc / (St + Sc) on the right side of the above equation (4)
Is a term relating to the specific surface area of the carrier and the toner,
Specifically, it is a numerical value representing the ratio of the surface area occupied by the carrier to the total surface area of the composition in which the carrier and the toner are mixed in equal weight (hereinafter simply referred to as carrier surface area occupation ratio).

Therefore, in this aspect of the present invention, when the electrostatic image is developed with the two-component developer under the condition that the carrier surface area occupation ratio or its neighborhood value and the toner density are equal, The density is improved, the fog density is reduced, the resolution is improved, and the gradation is improved.

Toner concentration (Ct%) and carrier surface area occupation ratio (Sc / (St
+ Sc),%) can be evaluated by determining the ratio of the two, that is, k = Ct / [Sc / (St + Sc)] coefficient k.

This coefficient k differs depending on the shape of the ferrite carrier used, but in the present invention, this coefficient k has been described above.
By setting the value of 0.80 to 1.07, especially in the range of 0.90 to 1.04 for spherical ferrite particles, high image density, low fog density, high resolution and excellent gradation can be obtained. As a result, the effect is achieved in which even after continuous copying of 70,000 sheets, there is almost no decrease.

Development Conditions In the present invention, the development clearance (d) is easily adjusted by mechanically adjusting the relative position between the photosensitive drum and the development sleeve.

On the other hand, the electric resistance of the magnetic brush of the two-component developer can be adjusted by various means. That is, it goes without saying that ferrite carriers and toner particles having electric resistance within a certain range are selected, but the resistance of the magnetic brush can be increased by further increasing the amount of toner particles or decreasing the diameter of toner particles. Grows. Also, the resistance of the magnetic brush increases as the diameter of the ferrite carrier increases. Of course, reversing these results in the opposite.

In the present invention, a bias voltage is applied between the photoconductor drum and the developer sleeve. Although this bias voltage sufficiently injects charges into the toner during development, it causes discharge breakdown to the photoconductor and the magnetic brush. It is specified so that such troubles will not occur. This voltage is generally suitable in the range of 100 to 300 volts, in particular 150 to 250 volts. The polarity of the bias voltage is, of course, selected so that it becomes positive when the charge on the photoconductor is positive, that is, the same polarity. According to the present invention, by adopting the above-mentioned developing conditions, it becomes possible to develop by applying a relatively low bias voltage, and as a result, the printing durability of the photoconductor can be improved.

In developing the magnetic brush of the present invention, the bristle cutting of the magnetic brush is determined so that the magnetic brush on the surface of the photoconductor is sufficiently rubbed in the above-mentioned clearance d. Generally, the development clearance d is 1.1 to 3.0 times, especially
It is desirable to perform panicle cutting so that the panicle length is 1.2 to 2.0 times. In the present invention, since the ferrite carrier having a small residual magnetization is used, it is one of the advantages that it is possible to cut the ears at small intervals.

During development, the magnet in the sleeve is fixed, and only the sleeve is rotated to move the magnetic brush in the same direction as the rotation direction of the sleeve, or the magnet in the sleeve is rotated and one sleeve is fixed, Either a method of moving the magnetic brush in the direction opposite to the rotating direction of the magnet or a method of rotating both the magnet and the sleeve to move the magnetic brush can be adopted.

The developing method of the present invention is applied to high-speed development of an amorphous silicon-based photoconductor, but the peripheral speed of the amorphous silicon photoconductor is generally 12 to 27 m / min, and particularly 18 to 24 m / min. It is a feature of the present invention that high density and high quality images can be obtained even when applied to a copying method.

(Examples and operational effects) The excellent operational effects of the present invention will be described in the following examples.

(Example) Preparation of toner 100 parts by weight of styrene-acrylic resin, 9 parts by weight of carbon black, wax (manufactured by Sanyo Kasei Co., Viscole 550-P)
A mixture of 2 parts by weight and 1 part by weight of a negative charge control agent (Hodogaya Chemical Co., Ltd., Spiron Black TRH) is melt-kneaded and dispersed sufficiently in a hot three-roll mill, and after cooling the kneaded product, it is about 2 mm in size. Coarsely pulverized and further finely pulverized using a jet mill. The finely pulverized product was classified several times to have a particle size distribution of 5 to 20 μm, and 0.1% by weight of hydrophobic silica (R-972 manufactured by Nippon Aerosil Co., Ltd.) was added and mixed to obtain a surface-treated product. Obtained as a toner.

When the electrical properties of the obtained toner were measured, the volume specific resistance was 8.6 × 10 ¹⁴ Ω-cm and the relative dielectric constant was 2.9.

Measurements were performed at a distance between electrodes 0.65 mm, the electrode plate area of 1.43 cm ² and the inter-electrode load of 105 g / cm ² conditions. The specific surface area of the toner was 4235 cm ² / g.

Adjustment of carrier and developer As carrier, particle size distribution is 35 to 105 μm, average particle size is 85
A μm acrylic resin coated ferrite carrier was used. The specific surface area of the carrier was 212 cm ² / g. By combining this carrier with the toner, several kinds of developers having an appropriate toner concentration of 5% obtained from the above-described calculation formula were prepared.

Experiment Electrophotographic copying machine DC
-513Z (manufactured by Mita Kogyo Co., Ltd.) was modified and used in a machine equipped with an amorphous silicon photosensitive drum to perform a copy image test. As the photoconductor, a-Si: H doped with boron is provided on an aluminum substrate having a diameter of 119 mm so as to have a thickness of 33 μm by a glow discharge decomposition method. This photosensitive drum is charged by corona discharge so that the surface potential becomes 450 V, and then image exposure is performed through an optical system whose lens surface is coated so as to cut a wavelength of 625 mm or less. Development bias voltage +
It was developed under 100V. After the developed toner image was transferred to a copy sheet and fixed, image evaluation was performed. Table of the results
Shown in 1.

[Brief description of drawings]

FIG. 1 is a diagram for explaining the developing conditions used in the present invention, FIG. 2 is a diagram for explaining the criticality of the particle diameter of the toner used in the present invention, and FIG. 3 is an electrophotographic method to which the present invention is preferably applied. It is a schematic diagram for explaining. 2 ... Amorphous silicon photoconductor layer, 7 ... Development mechanism.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location G03G 9/10 (72) Inventor Hiroyuki Nonaka 1-2-2 Tamatsukuri, Higashi-ku, Osaka-shi, Osaka Mita Within Kogyo Co., Ltd. (56) Reference JP 59-139056 (JP, A) JP 59-172660 (JP, A)

Claims (1)

[Claims] 1. An electrostatic image is formed on a photoreceptor having an amorphous silicon photoconductive layer and is composed of a mixture of magnetic carrier particles and toner particles chargeable by friction of the magnetic carrier particles. The component type developer is supplied onto a developing sleeve provided with a magnet in a non-magnetic sleeve to form a magnetic brush of the developer, and the photoconductive layer and the magnetic brush are provided between the photoconductor and the sleeve. In the developing method, which comprises rubbing the toner while a bias voltage is applied to the toner to form a toner image corresponding to the electrostatic image, the two-component developer is a magnetic brush between the sleeve and the photoreceptor surface. A ferrite carrier whose measured electrical resistance is in the range of 3 × 10 ^{6 to} 5 × 10 ⁷ Ω and a median diameter of 5 to 20
microparticles having a particle size of 5 μm or less and substantially zero content of electrophotographic toner particles having a volume resistance of 1 × 10 ¹³ Ω-cm or more at a weight ratio of 100: 3 to 100: 11. It is a developer and the clearance between the sleeve and the photoconductor is d (mm).
And the electric resistance measured as a magnetic brush between the sleeve of the two-component developer and the surface of the photoconductor is R (Ω), the following formula 2 × 10 ⁷ ≦ R ≦ 5 × 10 ⁸ (1) Under conditions that satisfy the condition, the moving speed of the photoconductor should be 12 to 27 m / mi.
A high-speed development method characterized in that development is performed within a range of n.