JP2006189563A - Developing roll and development device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing roll which is improved in durability is improved relative to repeated deformation caused by compression stress and tensile stress applied on the surface of the developing roll, by controlling the degree of cross linking of a resin forming the toner holding layer of the surface of the developing roll, and to provide a development device that uses the developing roll improved in surface durability. <P>SOLUTION: The developing roll 1 is used in the development device, in which a thin film of toner held on a conductive shaft 2, an elastic semiconductive layer 3 disposed on the conductive shaft body 2, and the toner holding layer 4 disposed around the elastic semiconductive layer 3 is formed into a toner layer of a specific thickness by a layer forming member and then an electrostatic latent image, formed on a latent image carrier, is rendered visible. The percentage of the gel of the resin forming the toner holding layer 4 of the developing roll 1 is 60% or higher. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention comprises a triboelectric charging member comprising a conductive shaft and an elastic semiconductive layer positioned outside the conductive shaft, and further supported in a thin film layer state on a toner carrying layer provided on the outer periphery of the elastic semiconductive layer. The present invention relates to a developing roll used in a developing device that visualizes an electrostatic latent image formed on a latent image holding member after the toner is layered to a predetermined toner layer thickness by a layer forming member, and a developing device using the developing roll.

  Conventionally, for example, in an electrophotographic apparatus such as a copying machine or a printer, or an electrostatic recording apparatus, a nonmagnetic one-component developer is supplied to a photosensitive drum holding a latent image, and the developer is applied to the latent image on the photosensitive drum. A contact development method is known as a development method for visualizing a latent image by attaching the latent image.

  For example, there is a developing roll configured by concentrically laminating a conductive elastic layer made of a rubber elastic body and a surface layer made of a resin layer around a conductive shaft body in this order (see Patent Document 1). ).

  In addition, the conductive material and the elastic semiconductive layer positioned outside the conductive material are provided as a toner-carrying layer, and the toner is formed on the latent image carrier by the frictionally charged toner carried in a thin film state on the carrier layer. In the developing device that visualizes the electrostatic latent image, the developing roll is required to have characteristics such as conductivity, environmental resistance, low hardness, frictional charging characteristics, and toner transportability. In response to such demands, developing rolls made of urethane rubber, NBR, silicone rubber or the like and made semiconductive by adding a conductivity imparting agent are well known (Patent Document 1, Patent Document 2). checking).

  In addition to the characteristics described above, these developing rolls are also required to have stability in printing characteristics when left in a printer after being left under high temperature and high humidity or after being printed for a long time.

  In the contact charging method as described above, the developing roll of the charging member made of low-hardness rubber or urethane resin is always in contact with the photosensitive drum of the non-charging member, so that a stable contact area between the two is ensured. The stress due to the contact pressure acts on the toner carrying layer on the surface of the developing roll. Therefore, the surface of the developing roll that comes into contact with the photosensitive drum is deformed, and when the development process is speeded up and lengthened, repeated deformation due to the compressive stress and tensile stress acting on the surface of the developing roll occurs. The frequency increased, and the surface of the developing roll might be damaged. If the surface of the developing roll is damaged, transfer of the triboelectrically charged toner and defective cleaning of the developing roll by the cleaning blade occur, and normal printing cannot be performed.

In addition, in order to improve the durability of the developing roll, the surface of the developing roll is also coated with a fluorine resin, but sufficient durability is maintained without impairing other characteristics such as toner chargeability and transportability. It is the present situation that does not lead to obtaining.
JP 2000-330372 A JP 2001-132730 A

  Accordingly, in order to solve the conventional problems as described above, the present invention manages the degree of cross-linking of the resin forming the toner carrying layer on the surface of the developing roll, thereby providing a toner carrying layer on the surface of the developing roll. It is an object of the present invention to provide a developing roll having improved durability against repeated deformation due to compressive stress and tensile stress acting on it. Another object of the present invention is to provide a developing device using such a developing roll having improved surface durability.

  The present invention adopts the following means in order to realize the above-described problems.

  According to a first aspect of the present invention, a thin film is formed on a conductive shaft, an elastic semiconductive layer positioned outside the conductive shaft, and a toner carrying layer provided on an outer surface of the elastic semiconductive layer. A developing roll for use in a developing device for visualizing an electrostatic latent image formed on a latent image carrier after forming a layer of a triboelectrically charged toner carried in a state to a predetermined toner layer thickness by a layer forming member. The gel fraction of the resin forming the toner carrying layer is 60% or more, and the surface brightness of the toner carrying layer is 30 to 220.

  The invention according to claim 2 is characterized in that, in addition to the constitution according to claim 1, the surface roughness of the toner carrying layer is JIS (B0601) ten-point average roughness Rz of 2 to 10 μm.

According to a third aspect of the present invention, in addition to the configuration of the second aspect, an electric resistance value between the conductive shaft body and the surface of the toner carrying layer is 1 × 10 ⁴ to 10 ⁹ Ω. It is characterized by that.

  According to a fourth aspect of the present invention, there is provided a developing device according to any one of the first to third aspects, wherein a triboelectrically charged toner is carried on the surface of the toner carrying layer of the developing roll, and the triboelectrically charged toner film is formed. After the formation, the toner carrying layer is brought into contact with the latent image holding member holding the electrostatic latent image on the surface, and the frictionally charged toner is attached to the surface of the latent image holding member from the thin film of the friction charging toner. The electrostatic latent image is visualized.

  Since the present invention employs the configuration as described above, according to the first aspect of the present invention, the gel fraction of the resin that forms the toner carrying layer on the surface of the developing roll is regulated to 60% or more. As a result, the degree of cross-linking of the resin forming the toner carrying layer can be guaranteed to be a certain level or more, and the durability against repeated deformation due to the compressive stress and tensile stress acting on the toner carrying layer on the surface of the developing roll is improved. A developing roll is obtained.

  Further, by setting the surface brightness of the toner carrying layer 4 to 30 to 220, it is possible to obtain a good image having an appropriate density and having no density unevenness and high dot reproducibility.

  According to the second aspect of the present invention, by regulating the surface roughness of the surface of the developing roll within a predetermined range, the action of attaching the toner to the charged portion of the photosensitive drum becomes more stable. In addition to the above effect, a high-definition and high-quality printed image can be obtained.

  According to the invention described in claim 3, since an appropriate development bias can be obtained by defining the electric resistance value between the conductive shaft body and the surface of the toner carrying layer within a predetermined range, A clear printed matter can be obtained without fading.

  According to the fourth aspect of the present invention, the triboelectrically charged toner is carried by the developing roll having improved durability against repeated deformation caused by compressive stress and tensile stress acting on the toner carrying layer on the surface of the developing roll. After the thin film is formed, the toner carrying layer comes into contact with the latent image holding member holding the electrostatic latent image on the surface, and the toner is attached to the surface of the latent image holding member from the toner thin film, and the electrostatic latent image is Since it will be visualized, a high-definition and high-quality printed image can be obtained.

  Hereinafter, description will be given of a developing roll and a developing device using the same according to an embodiment of the present invention. However, the present invention is not limited to this example.

  FIG. 1 is a cross-sectional view of a developing roll according to an embodiment of the present invention.

  As shown in FIG. 1, the developing roll 1 includes a columnar conductive shaft body 2 and a cylindrical elastic semiconductive layer 3 that covers the surface of the conductive shaft body 2. On the outer peripheral portion of the elastic semiconductive layer 3, a toner carrying layer 4 capable of carrying toner in a thin film state is provided.

  The conductive shaft body 2 includes, for example, (1) a metal shaft body made of iron, aluminum, stainless steel, brass, etc., and (2) a metal on the surface of a thermoplastic resin or thermosetting resin core body. Shaft body plated with film, (3) Shaft body with metal film deposited on the surface of thermoplastic resin or thermosetting resin core, (4) Conductivity imparting agent on thermoplastic resin or thermosetting resin What is necessary is just the shaft etc. which were integrally formed with the resin composition which mix | blended carbon black, metal powder, etc.

  The elastic semiconductive layer 3 is made of silicone rubber, ethylene-propylene-diene rubber, polyurethane rubber, chloroprene rubber, natural rubber, butyl rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene rubber, nitrile rubber, ethylene-propylene rubber, acrylic rubber. , And a mixture thereof, which is one or more selected from so-called rubber or elastomer as a main component.

  These rubbers or elastomers include fillers such as fumed silica, precipitated silica and reinforcing carbon, metal powders such as nickel, aluminum and copper, metal oxides such as zinc oxide and tin oxide, and barium sulfate. , Conductive filler with tin oxide coated on core material such as titanium oxide, potassium titanate, etc. was compounded and kneaded with vulcanizing agents such as peroxide, hydrogen siloxane in the presence of platinum catalyst, isocyanate, etc. Things are used.

The material for forming the toner carrying layer 4 is not particularly limited,
Examples include alkyd resins, alkyd resin modified products such as phenol modification and silicone modification, oil-free alkyd resins, acrylic resins, silicone resins, and mixtures thereof. In order to form the toner carrying layer 4 using these single / mixture resins, a method of coating the surface of the elastic semiconductive layer 3 with these single / mixture resins is employed. That is, the developing roll 1 according to the embodiment of the present invention has the elastic semiconductive layer 3 on the conductive shaft 2 and the toner carrying formed on the outer peripheral portion of the elastic semiconductive layer 3 by resin coating. It is preferable to have the layer 4.

  The surface of the developing roll 1 is brought into contact with the photosensitive drum by using the developing device and performs relative movement, so that compressive stress and tensile stress act to cause repeated deformation. Therefore, it is required to have high durability against the repeated deformation. Is done. Therefore, in the present invention, the degree of crosslinking of the resin forming the toner carrying layer 4 on the surface of the developing roll 1 is controlled, and specifically, the gel fraction of the resin forming the toner carrying layer 4 is 60% or more. By defining the above, sufficient durability against repetitive deformation of the surface of the developing roll 1 is ensured.

  Here, as will be apparent from the examples described later, if the gel fraction is less than 60%, the durability against repeated deformation of the toner carrying layer 4 on the surface of the developing roll 1 cannot be maintained, and transfer defects and cleaning are not achieved. It has been confirmed that a printed matter having a defect and resulting in fogging and fading of toner is produced. And in the evaluation by the final printed matter, when sufficient durability against repeated deformation of the surface of the developing roll 1 is obtained, it can be said that the gel fraction is more preferably 70% or more.

  Next, in the developing roll 1 according to the embodiment of the present invention, it was ascertained from the experimental example described later that the surface luminance of the toner carrying layer 4 affects the printing characteristics.

  That is, when the surface brightness of the toner-carrying layer 4 is less than 30, the image density of the black solid print sample becomes higher than necessary, and the density unevenness occurs in the intermediate tone print sample, resulting in a decrease in dot reproducibility. It was. On the other hand, when the surface brightness of the toner carrying layer 4 exceeds 220, the image density of the black solid print sample is low, and the paper as the print medium is seen through, making it difficult to obtain a good image. Therefore, it can be said that a good image can be obtained by setting the surface brightness of the toner carrying layer 4 to 30 to 220. Moreover, it can be said that the value is more preferably 50 to 200, and further preferably 60 to 140.

  Here, the reason why there is no unit in the surface luminance is that the value (measured by a surface luminance value measuring apparatus employing a CCD camera capable of recognizing a grayscale image with a resolution of 256 gradations in the test methods of Examples and Comparative Examples described later ( This is because the minimum value: 0 to the maximum value: 255) is adopted as the luminance value.

  Further, in the developing roll 1 according to the embodiment of the present invention, the surface roughness (JIS (B0601) ten-point average roughness Rz) of the toner carrying layer 4 is regulated within a predetermined range by an experimental example described later. It was confirmed that a good image was obtained.

  That is, when the surface roughness Rz of the toner carrying layer 4 is less than 2 μm, the image density of the black solid print sample is low, and when the surface roughness Rz exceeds 10 μm, the image density of the black solid print sample is too high, Toner fog is likely to occur, and the resolution also decreases. Therefore, it can be said that a good image can be obtained by setting the surface roughness Rz of the toner carrying layer 4 to 2 to 10 μm.

  In order to adjust the surface brightness and the surface roughness Rz of the toner carrying layer 4 on the surface of the developing roll 1 to the predetermined ranges as described above, (1) In addition to the method of forming a resin coat layer on the surface, (2 And a method of selecting the type of rubber material, additive component, and the like constituting the elastic semiconductive layer 3, and (3) a method of controlling the formation method of the elastic semiconductive layer 3.

  Further, in the developing roll 1 according to the embodiment of the present invention, an electrical resistance value between the conductive shaft body 2 of the developing roll 1 and the toner carrying layer 4 on the surface of the developing roll 1 is set to a predetermined value by an experimental example described later. It was confirmed that a good image can be obtained by defining the above range.

That is, if the electrical resistance value between the conductive shaft 2 of the developing roll 1 and the toner carrying layer 4 on the surface of the developing roll 1 is less than 1 × 10 ⁴ Ω, the developing bias is applied too much, and the black solid print sample Since the image density becomes too high, toner fog is likely to occur, and the resolution is also lowered. Further, if this electrical resistance value exceeds 1 × 10 ⁹ Ω, the developing bias is not applied and the developability is lowered, the image density of the black solid print sample is low, and the paper as the printing medium can be seen through, It becomes difficult to obtain a good image. Therefore, it can be said that a good image can be obtained if the electrical resistance value between the conductive shaft body 2 and the surface of the toner carrying layer 4 is in the range of 1 × 10 ⁴ to 10 ⁹ Ω.

  Hereinafter, manufacturing methods of Examples and Comparative Examples of the developing roll 1 according to the present invention and test results of the results obtained will be described.

    [Example 1]

As the conductive shaft 2, a SUS22 electroless nickel plated metal shaft with a diameter of 10 mm and a length of 275 mm was used, and a silicone primer (trade name: Primer No. 16, Shin-Etsu Chemical Co., Ltd.) was used on the metal shaft. (Made by Co., Ltd.) was applied, and baked in a gear oven at 150 ° C. for 10 minutes.

  As a material of the elastic semiconductive layer 3, 100 parts by mass of methyl vinyl silicone raw rubber (trade name: KE-78VBS, manufactured by Shin-Etsu Chemical Co., Ltd.) and dimethyl silicone raw rubber (trade name: KE-76VBS, Shin-Etsu Chemical ( 20 parts by mass of carbon black (trade name: Asahi Thermal, manufactured by Asahi Carbon Co., Ltd.) 10 parts by mass, fumed silica-based filler (trade name: AEROSIL 200, manufactured by Nippon Aerosil Co., Ltd.) Part, platinum catalyst (trade name: C-19A, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 part by mass, hydrogen siloxane (trade name: C-19B, manufactured by Shin-Etsu Chemical Co., Ltd.) 2 parts by mass Then, a silicone rubber composition was prepared by kneading with a pressure kneader.

  Next, the silicone rubber composition is dispensed through a crosshead with an extruder and integrated with the conductive shaft body 2, and heated and heated in a gear oven at 250 ° C. for 30 minutes to form the conductive shaft body 2. The surface was vulcanized and bonded to a cylindrical shape having an outer diameter of 18 mm. Further, secondary vulcanization was performed at 200 ° C. for 4 hours in a gear oven to form the elastic semiconductive layer 3.

  After secondary vulcanization, the outer peripheral surface of the elastic semiconductive layer 3 is polished by a cylindrical grinder equipped with a GC # 400 grindstone, and a roll having a diameter of 16 mm and a rubber part (elastic semiconductive layer 3) of 230 mm in length A substrate was prepared.

Next, on the surface of the elastic semiconductive layer 3, 100 parts by mass of urethane-based paint (trade name: NIPPOLAN 5196, manufactured by Nippon Polyurethane Co., Ltd.) and fumed silica-based filler (trade name: AEROSIL 200, Nippon Aerosil) A coating solution to which 10 parts by mass and 18 parts by mass of a blocked isocyanate crosslinking agent were added was applied once by spray coating, followed by heat curing at 150 ° C. for 90 minutes. The toner carrying layer 4 on the surface of the elastic semiconductive layer 3 of the developing roll 1 thus completed had a gel fraction of 96%, a surface brightness of 120, and a surface roughness Rz of 4 μm. The electric resistance value between the conductive shaft body 2 and the surface of the toner carrying layer 4 was 1 × 10 ⁶ Ω.

    [Example 2]

  Example 2 is a developing roll 1 manufactured in the same manner as in Example 1 except that the toner carrier layer curing conditions of 150 ° C. and 90 minutes in Example 1 were changed to 150 ° C. and 45 minutes. The gel fraction of Example 2 was 80%.

    [Example 3]

  Example 3 is a developing roll 1 manufactured in the same manner as in Example 1 except that the toner carrying layer curing conditions of 150 ° C. and 90 minutes in Example 1 were changed to 150 ° C. and 30 minutes. The gel fraction of Example 3 was 60%.

    [Comparative Example 1]

  Comparative Example 1 is a developing roll 1 manufactured in the same manner as in Example 1 except that the toner carrying layer curing conditions of 150 ° C. and 90 minutes in Example 1 were changed to 150 ° C. and 20 minutes. The gel fraction of Comparative Example 1 was 50%.

    [Comparative Example 2]

  Comparative Example 2 is a developing roll 1 manufactured in the same manner as in Example 1 except that the toner carrying layer curing conditions of 150 ° C. and 90 minutes in Example 1 were changed to 140 ° C. and 30 minutes. The gel fraction of Comparative Example 2 was 40%.

    [Comparative Example 3]

  In Comparative Example 3, the developing roll 1 was produced by the same production method except that the amount of the fumed silk filler added to the urethane-based paint of Example 1 was 40 parts by mass. The surface brightness of Comparative Example 3 was 17.

    [Comparative Example 4]

  In Comparative Example 4, the developing roll 1 was produced by the same production method except that the fumed silk filler was not added to the urethane-based paint of Example 1. The surface brightness of Comparative Example 4 was 230.

    [Test method]

  The gel fraction, surface brightness, surface roughness Rz, and electrical resistance values for Examples and Comparative Examples were obtained by the following measuring methods, and the following tests were performed for durability evaluation.

  (1) Gel fraction

  First, without applying a primer to the surface of the elastic semiconductive layer 3, a conductive urethane resin layer was applied by the same method as in Example 1, cured at 160 ° C. for 1 hour, sufficiently cooled, and then electrically conductive. The functional urethane resin layer is removed from the surface of the elastic semiconductive layer 3. The weight of the removed conductive urethane resin layer (sample) is measured. Next, the conductive urethane resin layer (sample) is immersed in a toluene solution of about 100 times weight (room temperature 23 ° C., 4 hours), and then the conductive urethane resin layer (sample) is taken out from the toluene solution at 150 ° C. After drying for 1 hour and sufficiently cooling, the weight of the conductive urethane resin layer (sample) is measured.

  From the weight of the conductive urethane resin layer (sample) before dipping in the toluene solution and the weight of the conductive urethane resin layer (sample) after dipping in the toluene solution and drying, the gel fraction is calculated by the following formula: Is calculated.

(Equation 1)
Gel fraction (%) = (weight after immersion of sample / weight before immersion of sample) × 100

  (2) Surface brightness

  The surface brightness of the toner carrying layer 4 on the surface of the developing roll 1 was measured by a surface brightness value measuring apparatus shown in FIG.

  This surface luminance value measuring apparatus includes an objective lens 5 (trade name: CF IC BD Plan20X, manufactured by Nikon Corporation), a CCD camera 6 (trade name: XC-003, manufactured by Sony Corporation), and an illumination lamp 7. A microscope main body 8 (trade name: EPI-U, manufactured by Nikon Co., Ltd.) composed of (Philips 77241). The developing roll 1 is set at the lower part of the microscope main body 8 and supplied to the illumination lamp 7 The voltage of the developing roll 1 is adjusted to DC 10 V by the voltage regulator 9, and the developing roll 1 is illuminated by the vertical irradiation method.

  The CCD camera 6 is connected to a computer 10 on which image processing software (trade name: DA-6000, manufactured by Oji Scientific Instruments) is installed. The captured image is taken into the computer 10 and the captured image is captured. Is analyzed by image processing software, and the surface luminance value is measured. In the measurement, the surface luminance values at three locations were measured for one developing roll 1, and the average value was used.

  (3) Surface roughness Rz

  The developing roll 1 is set on a surface roughness meter (trade name: 590A, Tokyo Seimitsu Co., Ltd.) equipped with a measurement probe having a tip radius of 2 μm, a measurement length of 2.4 mm, a cutoff wavelength of 0.8 mm, and a cutoff type Gaussian. Was used to measure the surface roughness Rz. As the measurement frequency, three surface roughnesses Rz were measured for one developing roll 1 and the average value thereof was used.

  (4) Electric resistance

  Using an electric resistance meter (trade name: ULTRA HIGH RESISTANCE METER R8340A) manufactured by Advance, place the developing roll 1 horizontally, the thickness is 5 mm, the width is 30 nm, and the length is the entire rubber part (elastic semiconductive layer 3). An aluminum plate that can be placed is used as an electrode, and a load of 500 g is supported at both ends of the conductive shaft 2 of the developing roll 1, and DC 100 V is supplied between the conductive shaft 2 and the electrode, The value of the electric resistance meter after 1 second was read to obtain an electric resistance value.

  (5) Durability

  As a test for confirming durability against repeated deformation of the toner-carrying layer 4 on the surface of the developing roll 1, a continuous printing test using a printing tester was performed, and the presence or absence of streaks in the printed image was visually determined.

  Specifically, the developing roll 1 manufactured in the example and the comparative example is mounted on the test cartridge at the position of the black toner cartridge of a commercially available printer, and the room temperature is 23 ° C. and the humidity is 50%. ) Was left for a whole day and night, and then black solid printing was performed. The images were observed every 500 sheets, and the durability was evaluated.

    [Test results]

  Table 1 shows the measurement results of the gel fraction, the surface brightness, the surface roughness Rz, and the electrical resistance values and the test results for evaluating durability for the examples and comparative examples.

  When the gel fraction of the resin forming the toner carrying layer 4 on the surface of the developing roll 1 is 60% or more as in Examples 1 to 3, the compressive stress and the tensile stress acting on the surface of the developing roll 1 Therefore, in the developing device using such a developing roll 1, a high-definition and high-quality printed image can be obtained.

Further, the surface brightness of the surface of the toner carrying layer 4 is adjusted to 30 to 220 cd / m ² , and the surface roughness of the toner carrying layer 4 is adjusted to a range of 1 to 20 μm in terms of JIS ten-point average roughness Rz. In this case, since the durability against repetitive deformation due to the compressive stress and tensile stress acting on the surface of the developing roll 1 can be improved, the cleaning blade can be used even in an environment where the development process is accelerated and prolonged. Therefore, in the developing device using such a developing roll 1, a high-definition and high-quality printed image can be obtained.

  In Comparative Examples 1 to 4, since the gel fraction of the resin forming the toner carrying layer 4 corresponding to the surface portion of the developing roll 1 is 40 to 50% and the value is less than 60%, the surface of the developing roll 1 The durability against repetitive deformation due to compressive stress and tensile stress acting on the film was inferior, resulting in poor cleaning performance using a cleaning blade, and scratches were confirmed on the printed image from the 0.5Kth sheet.

It is a cross-sectional view of the developing roll which is embodiment of this invention. It is a conceptual diagram of a surface luminance value measuring apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Developing roll 2 Conductive shaft 3 Elastic semiconductive layer 4 Toner carrying layer

Claims (4)

A conductive shaft, an elastic semiconductive layer positioned outside the conductive shaft, and a frictionally charged toner carried in a thin film state on a toner carrying layer provided on an outer periphery of the elastic semiconductive layer. A developing roll used in a developing device for visualizing an electrostatic latent image formed on a latent image carrier after forming a layer with a predetermined toner layer thickness by a layer forming member, the resin forming the toner carrying layer A developing roll having a gel fraction of 60% or more and a surface brightness of the toner carrying layer of 30 to 220. 2. The developing roll according to claim 1, wherein the toner carrying layer has a surface roughness of JIS (B0601) 10-point average roughness Rz of 2 to 10 μm. The developing roll according to claim 2, wherein an electrical resistance value between the conductive shaft and the surface of the toner carrying layer is 1 × 10 ⁴ to 10 ⁹ Ω. The triboelectrically charged toner is carried on the surface of the toner carrying layer of the developing roll according to any one of claims 1 to 3 to form a thin film of the triboelectrically charged toner, and then the toner carrying layer is formed into an electrostatic latent image. In contact with the latent image holding member held on the surface, the frictionally charged toner is adhered to the surface of the latent image holding member from the thin film of the frictionally charged toner, and the electrostatic latent image is visualized. Development device.

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