EP0967528B1 - Entwicklungsvorrichtung - Google Patents

Entwicklungsvorrichtung Download PDF

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Publication number
EP0967528B1
EP0967528B1 EP19990111926 EP99111926A EP0967528B1 EP 0967528 B1 EP0967528 B1 EP 0967528B1 EP 19990111926 EP19990111926 EP 19990111926 EP 99111926 A EP99111926 A EP 99111926A EP 0967528 B1 EP0967528 B1 EP 0967528B1
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EP
European Patent Office
Prior art keywords
developer
bearing body
developing
image
toner
Prior art date
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Expired - Lifetime
Application number
EP19990111926
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English (en)
French (fr)
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EP0967528A2 (de
EP0967528A3 (de
Inventor
Tadashi Iwamatsu
Nobuyuki Azuma
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Sharp Corp
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Sharp Corp
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Publication of EP0967528A2 publication Critical patent/EP0967528A2/de
Publication of EP0967528A3 publication Critical patent/EP0967528A3/de
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Publication of EP0967528B1 publication Critical patent/EP0967528B1/de
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/06—Developing
    • G03G13/08—Developing using a solid developer, e.g. powder developer

Definitions

  • the present invention relates to a developing device of a one-component developing system, which is provided in an image-forming apparatus of the electrophotographing system such as a copying machine, a printer, etc., so as to develop an electrostatic latent image formed on the surface of a photoconductive member.
  • An image-forming apparatus such as a copying machine and a printer which uses an electrophotographic system is provided with a developing device for developing an electrostatic latent image formed on the surface of a photoconductive member.
  • a developing device has been put into practical use in which a developing roller using the magnetic brush system, which carries a two-component developer consisting of toner and magnetic carrier to a developing area facing a photoconductive member by utilizing a magnetic force, is provided, and after completion of the developing process, the developer is recovered into a developing vessel.
  • the carrier accounts for a greater ratio in the developer, making it necessary to increase the size of the developer vessel storing the developer; this tends to make an entire developing device larger.
  • stirring members, etc. are required so as to control the toner density and to make constant the quantity of charge in the toner in the developer, and this plurality of stirring members are one of the reasons that miniaturization of the developing device has been limited.
  • a developing device of one-component developer system which uses a one-component developer consisting of toner without containing a carrier, has been proposed and put into practical use.
  • the developing device using such a one-component developer it is neither necessary to control the toner density, nor to provide a carrier, so that the volume of the developing vessel can be greatly reduced, thereby making it possible to miniaturize the developing device.
  • this one-component developer system is superior in ease of maintenance, etc. In other words, since no exchange for deteriorated developer, especially for developer containing deteriorated carrier, is required, no corresponding maintenance is required.
  • predetermined voltages are applied to respective members constituting the developing device, such as the developing roller and supplying roller, in order to develop an electrostatic latent image formed on the photoconductive member with high fidelity.
  • toner and the respective members form major factors in determining the developing characteristic.
  • the quantity of charge in toner and the resistivity of the developing roller greatly affect the developing characteristic.
  • the relationship between the specific charge q/m (quantity of charge per unit mass) and the developing characteristic is indicated by a characteristic shown in Fig. 10, wherein, when the specific charge is small, the electric potential difference from the developing start voltage to the developing end voltage is small.
  • this characteristic is referred to as "a rising developing gamma characteristic”.
  • this characteristic is referred to as "a flat developing gamma characteristic”. Therefore, if a developing device has great fluctuations in the toner specific charge, it has great fluctuations in the developing characteristics, failing to form good images. Since conventional one-component developing devices fail to sufficiently suppress the fluctuations in the specific charge, they tend to have degradation in the image quality, for example, the occurrence of developing ghost images.
  • the relationship between the developing roller resistivity and the developing characteristics is indicated by a characteristic shown in Fig. 8, wherein the greater the resistivity, the more flat developing gamma characteristic is exerted.
  • a characteristic shown in Fig. 8 wherein the greater the resistivity, the more flat developing gamma characteristic is exerted.
  • the toner charging characteristic be stabilized by using a charge-control agent and an externally added agent and that the developing characteristic be stabilized by allowing the developing roller to have a low resistivity; however, these efforts have not sufficiently achieved high image-quality yet.
  • the developer inherently contains specific charge fluctuations due to the distribution of toner particle sizes, that is, the specific charge fluctuates simultaneously with particle size fluctuations.
  • the application of a highly resistive developing roller tends to cause a problem of the occurrence of developing ghost images due to a charge accumulated on the surface of the highly resistive layer; in contrast, the application of a low resistive developing roller tends to cause a problem of degradation in the image quality due to dielectric breakdown in the toner layer and over-currents.
  • the objective of the present invention is to provide a developing device of the one-component developing system which can stabilize the developing characteristics and achieve a superior developing operation by preventing degradation in the image quality due to dielectric breakdown in the toner layer as well as developing ghost images caused by particle-size fluctuations in the developer.
  • the developing device of the present invention which develops an electrostatic latent image on the electrostatic-latent image bearing body, is provided with a developer-bearing body which bears one-component developer on its surface and develops the electrostatic latent image by contacting an electrostatic-latent-image bearing body, a developer-supplying member for supplying developer to the developer-bearing body, and a developer-layer regulating member which contacts the developer-bearing body so as to regulate the layer thickness of the developer that has been supplied by the developer-supplying member, and supposing that the volume-average particle size of the developer is Dbk, the developer at this time being maintained on the developer-bearing body as a layer that has been supplied by the developer-supplying member and again formed so as to have a predetermined thickness by the developer-layer regulating member after the developer-bearing body, on which the developer was formed as a layer having a predetermined thickness, carried out a colored-image developing process, and suppos
  • Fig. 1 is a schematic side view showing a developing device 4, which is aligned face to face mainly with a photoconductive member 1 (an electrostatic-latent-image bearing body) in an image-forming apparatus of the present embodiment.
  • Fig. 4 is a side view showing an essential portion of the structure of the image-forming apparatus provided with the developing device 4 of Fig. 1.
  • the present image-forming apparatus is constituted by a photoconductive member 1 and various image-forming process devices that are disposed in a manner so as to face the photoconductive member 1 on the periphery thereof.
  • the photoconductive member 1 which is placed virtually in the center of the image-forming apparatus main body and which is a drum-shaped image-bearing body for bearing an electrostatic latent image, is driven to rotate at a constant velocity in the direction of arrow A at the time of an image-forming operation.
  • the above-mentioned image-forming process devices include a charger 2 for uniformly charging the surface of the photoconductive member 1, an optical system (not shown) for irradiating an image M with light in accordance with a picture image, a developing device 4 related to the present invention which visualizes an electrostatic latent image that has been formed on the surface of the photoconductive member 1 by exposure with the optical system, a transferring device 5 for transferring a developed toner image (image of one-component developer 10) onto a sheet of paper P that has been appropriately transported, a cleaning device 6 for removing residual developer (toner) that has not been transferred onto the surface of the photoconductive member 1 after the transferring operation, a static-eliminating device 7 for eliminating an electrostatic charge remaining on the surface of the photoconductive member 1, etc., and these devices are arranged in this order in the rotation direction of the photoconductive member 1.
  • a number of sheets of paper P are housed in, for example, a tray or a cassette, and the sheets of paper housed therein are fed by a feeding means (not shown) sheet by sheet, and transported to a transferring area facing the photoconductive member 1, in which the above-mentioned transferring device 5 is placed, in a manner so as to coincide with the leading edge of a toner image formed on the surface of the photoconductive member 1. After this transferring operation, the paper P is separated from the photoconductive member 1, and transported to the fixing device 8.
  • the fixing device 8 which fixes the unfixed toner image transferred onto the paper as a permanent image, is constituted by a heat roller having a surface facing the toner image, with the surface being heated to a temperature at which the toner is fused and fixed, a pressure roller which allows the paper P pressed toward the heat roller to closely contact the heat roller, and other members.
  • the paper P which has passed through the fixing device 8, is ejected from the image-forming apparatus onto a discharge tray (not shown) through discharging rollers (not shown).
  • the optical system In the case when the image-forming apparatus is provided as a copying machine, the optical system, not shown, irradiates a copy document with light, and the reflected light from the document is projected as a light image M. Moreover, in the case when the image-forming apparatus is provided as a printer or a digital copying machine, the optical system projects a light image M obtained by ON/OFF driving a semiconductor laser in accordance with image data. In particular, in the digital copying machine, the image data, obtained by reading the reflected light from the copy document with an image reading sensor (CCD elements, etc.), is inputted to the optical system including the semiconductor laser from which a light image M in accordance with the image data is outputted.
  • CCD elements image reading sensor
  • conversion is made in accordance with image data from another processing apparatus, such as a word processor and a personal computer, so as to form a light image M, and this is projected.
  • This conversion to the light image M is carried out by utilizing not only a semiconductor later, but also an LED (Light Emitting Diode) element, a liquid crystal shutter, etc.
  • the photoconductive member 1 When an image-forming operation is started in the image-forming apparatus described above, the photoconductive member 1 is driven to rotate in the arrow direction, and the surface of the photoconductive member 1 is uniformly charged by the charger 2 to an electric potential having a specific polarity. After this charging process, a light image 3 is projected thereto from the optical system, not shown, so that an electrostatic latent image in accordance with the light image is formed on the surface of the photoconductive member 1. This electrostatic latent image is developed and visualized by the succeeding developing device 4.
  • this developing process is carried out by using one-component developer in such a manner that the toner is selectively attracted to the electrostatic latent image formed on the surface of the photoconductive member 1, for example, by an electrostatic force; thus, a developing operation is carried out.
  • the toner image thus developed on the surface of the photoconductive member 1, is electrostatically transferred onto a sheet of paper P, which has been appropriately transported in synchronism with the rotation of the photoconductive member 1, by the transferring device 5 disposed at the transferring area.
  • the toner image is transferred toward the paper P side by allowing the transferring device 5 to charge the back surface of the paper P with a polarity reversed to the polarity of charged toner.
  • the paper P is separated from the photoconductive member 1, and transported to the fixing device 8.
  • the toner image on the paper P is fused, pressed onto the paper P by a pressing force between rollers, and fixed thereon.
  • the paper, which has passed through the fixing device 8, is ejected onto the discharge tray (not shown), etc., installed outside of the image-forming apparatus as a sheet of paper P which has been subjected to the image-forming operation.
  • the developing device 4 includes a developer vessel 40, and is provided with a developing roller 41 (developer-bearing body) installed so as to freely rotate, a supply roller 42 (developer supplying member), an agitator or a screw roller 9, etc.
  • One-component developer for example, non-magnetic one-component developer (toner)
  • the agitator or a screw roller 9 is installed on the right side of the developer vessel 40 in Fig. 1 (on the side of the supply roller 42 opposite to the developing roller 41), and sends the one-component developer 10 supplied on demand into the developer vessel 40.
  • the developing roller 41 installed inside the developer vessel 40, rotates in the direction of arrow B in order to transport toner to a developing area at which one portion thereof is exposed so as to face the photoconductive member 1, and is allowed to rotate in the same direction as the photoconductive member 1 at the developing area.
  • the above-mentioned supply roller 42 is pressed onto the developing roller 41.
  • the developing roller 41 has a construction in which, for example, the surface of a metal roller (including a rotary shaft 41a) is coated with a high polymer elastic member.
  • a high polymer elastic member polyurethane, etc., in which carbon is dispersed, or an ion-conductive solid rubber, etc., is adopted; thus, it is possible to maintain a predetermined resistivity at which no toner fusion, etc., occurs, and consequently to provide an effective supply of a developing bias voltage, as will be described later. Additionally, a specific example will be given later of the construction of the developing roller 41 used in the present invention.
  • a driving motor not shown, is connected to the developing roller 41, and the developing roller 41 is driven to rotate in the arrow direction in the Figure.
  • the one-component non-magnetic toner 10 is attracted onto the surface of the developing roller 41 being rotated, and transported to the developing area facing the surface of the photoconductive member 1.
  • the press-contact area forms the developing area so that one-component developer 10 is attracted to the electrostatic latent image on the surface of the photoconductive member 1, thereby allowing the image to be developed.
  • the developing area at which the developing roller 41 and the photoconductive member 1 come into contact with each other, that is, a contact area is set to have a desired contact area S1 (cm 2 ). A detailed description will be given of the contact area S1 later.
  • the above-mentioned one-component developer 10 is a one-component non-magnetic toner having, for example, an average particle size of approximately 10 ⁇ m, and polyester toners or styrene-acrylic toners may be adopted.
  • a developing bias voltage Va is supplied from a developing bias power-supply circuit 11 to the developing roller 41.
  • the developing bias voltage Va is properly set at a voltage value with a polarity so as to allow toner to adhere to the electrostatic latent image formed on the photoconductive member 1 and also so as not to allow toner to adhere to the other area, that is, a non-image area.
  • the supply roller 42 is driven to rotate in a direction reversed to the rotation direction of the developing roller 41 (in the direction of arrow C in the Figure) at an opposing portion (press-contact area) to the developing roller 41.
  • the supply roller 42 is made of a material similar to that of the developing roller 41, and the adjustment of the electric resistance thereof can be made by using a resistance-adjusting material similar to that of the developing roller 41.
  • a foamed (porous) material may be adopted.
  • a bias voltage Vc is applied to the supply roller 42 from a bias power-supply circuit 12, and in general, the bias voltage is set so as to press toner toward the developing roller 41, that is, so as to repel toner on the supply roller 42 side and supply it to the developing roller 41.
  • the bias voltage Vc that is greater in the negative polarity side than the bias voltage Va applied to the developing roller 41 is applied to the supply roller 42.
  • the developing roller 41 and the supply roller 42 are connected to a driving motor, not shown, and rotated in the directions of arrows in the Figure so that toner is supplied to the developing roller 41, while residual toner on the surface of the developing roller 41 which has not been used is separated (removed) therefrom after the developing operation, by the supply roller 42.
  • the toner, supplied by the supply roller 42 is allowed to adhere to the surface of the developing roller 41, and before it is transported to the developing area facing the surface of the photoconductive member 1, it is regulated to a predetermined toner-layer thickness by a blade 43 (developer-layer regulating member) that is appropriately pressed onto the developing roller 41 so as to regulate the amount of toner adhesion to the developing roller 41.
  • the blade 43 is pressed onto the developing roller 41 with an appropriate pressure.
  • the blade 43 is constituted by blade forming members made of plate-shaped metal members, and its thick portion (face) in the vicinity of the tip is pressed onto the developing roller 41. Therefore, the one component developer 10 (toner), supplied to the developing roller 41, is regulated to a predetermined thickness with a predetermined quantity of static charge by the predetermined setting pressure and setting position of the blade 43, and transported to the developing area which faces and contacts the photoconductive member 1.
  • the blade 43 serving as a developer-layer regulating member has its one end secured to the developer vessel 40 side, with the other free end being pressed onto the surface of the developing roller 41 at the thick portion.
  • the regulating member 43 which is made of a metal plate, such as phosphor bronze or stainless steel (SUS), with a plate thickness of, for example, approximately 0.1 to 0.2 mm, is pressed onto the developing roller 41 with a predetermined pressure in the length direction (in the direction of the rotary shaft of the developing roller) at its thick portion in the vicinity of the tip thereof.
  • the amount of the one-component developer 10 that has been supplied by the supply roller 42 and supported on the surface of the developing roller 41 is made constant by the regulating member 43, and transported to the developing area that contacts the photoconductive member 1.
  • a predetermined voltage Vb is supplied to the blade 43 from the bias power-supply circuit 13.
  • This bias voltage Vb is set so that, for example, in the case of a toner with a negative polarity, it has a greater value in the negative polarity side than the bias voltage Va applied to the developing roller 41 so as to press the toner toward the developing roller 41.
  • the bias voltage Vb to be supplied to the blade 43 is set at the same electric potential as the developing bias voltage Va to be supplied to the developing roller 41, or at a value greater than that in absolute value.
  • the one-component developer 10 (toner), which has been transported to the developing area facing the photoconductive member 1, is allowed to selectively adhere to the surface of the photoconductive member 1 in accordance with an electrostatic latent image formed thereon so that the electrostatic latent image is visualized by the color of the toner. Then, the toner 10 that has not been used in the developing process is returned into the developer vessel 40 by the rotation of the developing roller 41. At the position related to the recovery, a toner reset member 44 for removing toner is installed in a manner so as to be pressed onto the developing roller 41.
  • This reset member 44 is placed before the supply roller 42 in the rotation direction of the developing roller 41 so that one end is secured to the developer vessel 40 so as to maintain an appropriate contact with the developing roller 41, with the other end being pressed onto the developing roller 41 by utilizing a spring property exerted by an area for allowing its thick portion on the other free end side to be pressed thereon.
  • the toner that has not been used in the developing process is static-eliminated and removed by the reset member 44 while being recovered into the developer vessel 40 by the rotation of the developing roller 41, and reused.
  • a bias voltage Vd for eliminating and removing a static charge from the toner is supplied to the reset member 44 from the power-supply circuit 14.
  • the developing device 4 transports the one-component developer 10 (toner) to the area facing the photoconductive member 1, and visualizes an electrostatic latent image on the surface of the photoconductive member 1, thereby forming a toner image.
  • the toner image on the surface of the photoconductive member 1 is transferred by the function of the transferring device 5 onto paper P that has been appropriately transported to the transferring area, as described earlier, and after having passed through the fixing device 8, ejected out of the image-forming apparatus.
  • an OPC (Optical Photo-Coupler) photoconductive member etc.
  • the surface of a conductive base made of metal or resin is coated with an under layer, a carrier generator layer (CGL) as the upper layer, and a carrier transport layer (CTL) having polycarbonate as its main ingredient as the outermost layer.
  • CGL carrier generator layer
  • CTL carrier transport layer
  • the photoconductive member is not limited thereby, and any bearing body for bearing an electrostatic latent image may be used.
  • the developing roller 41 is constituted by a rotary shaft 41a (conductive shaft) made of a core member of metal or low-resistance resin, and a semiconductive layer 46 coated thereon which is an elastic member having, for example, a relative dielectric constant of approximately 10.
  • a toner layer 45 is formed on the surface of this semiconductive layer 46.
  • those elastic members obtained as follows are preferably used: one containing as a base material a dispersion-type resistance adjusting resin which is obtained by mixing and dispersing either one or a plurality of conductive fine particles, such as carbon and TiO 2 (titanium oxide), to a resin selected from the group consisting of Ethylene Propylene Diene Terpolymer (EPDM), urethane, silicone, nitrile-butadiene rubber, chloroprene rubber, styrene-butadiene rubber and butadiene rubber; and one containing as a base material an electrical resistance adjusting resin which is obtained by adding to the above-mentioned resin either one or a plurality of ion conductive materials, for example, inorganic ion conductive substances, such as sodium perchloric acid, calcium perchloric acid and sodium chloride.
  • a dispersion-type resistance adjusting resin which is obtained by mixing and dispersing either one or a plurality of conductive fine particles, such as carbon
  • a silicon-type surface active agent (block copolymer of polysiloxane-polyalkylenoxide) is preferably used.
  • a heat-blow forming that is one of the methods for the above-mentioned foaming
  • appropriate amounts of the above-mentioned materials are blended and stirred in a mixing injection device, and this is injected into an injection extruding mold and heated at 80° C to 120° C, and thus injection-molded.
  • the heating time is preferably set at approximately 5 to 100 minutes.
  • a conductive metal core member (shaft) is placed in the center of a mold which has been preliminarily prepared, and the mixture is poured in the same manner as described above, and heated and cured for approximately 10 to 160 minutes; thus, an integrally molded product is obtained.
  • a carbon black for example Intermediate Super Abrasion Furnace (ISAF), High Abrasion Furnace (HAF), General Purpose Furnace (GPF), Semi Reinforcing Furnace (SRF), etc.
  • a carbon black which has a nitrogen-adsorption specific surface area of not less than 20 m 2 /g to not more than 130 m 2 /g and an amount of oil absorption (Dibutyl Phthalate (DBP)) of not less than 60 ml/g to not more than 120 ml/g is used, and 0.5 to 15 parts by weight (in some cases, at approximately 70 parts by weight) of this is blended to 100 parts by weight of polyurethane.
  • DBP oil absorption
  • soft polyurethane foam and polyurethane elastomers are preferably used.
  • the above-mentioned EPDM, urethane, silicone, nitrile-butadiene rubber, chloroprene rubber, butadiene rubber, etc. may be adopted.
  • the EPDM which contains ethylene, propylene and the third ingredient, for example, ethylidene norbornane, 1,4-hexadiene, etc., that are appropriately blended, is preferably set so as to have an ethylene content of 5 to 95 parts by weight, a propylene content of 5 to 95 parts by weight and a third-ingredient content of 0 to 50 parts by weight at iodine value.
  • the amount of blend of the carbon black is preferably set at 1 to 30 parts by weight with respect to 100 parts by weight of EPDM so as to obtain a superior dispersing property.
  • the carbon black to be used is ISAF, HAF, GPF, SRF, etc. as described above.
  • an ion conductive substance serving as a resistance-adjusting base material such as sodium perchloric acid and tetraethylammonium chloride
  • a surface active agent such as dimethylpolysiloxane and polyoxyethylenelauryl ether
  • the ion conductive material examples include, inorganic ionic conductive materials, such as sodium perchloric acid, calcium perchloric acid and sodium chloride, or organic ionic conductive materials, such as modified aliphatic dimethylethylammonium ethosulfate, stearyl ammonium acetate, lauryl ammonium acetate and octadecyltrimethylammonium perchlorate. Any one of these materials may be used, or a plurality of them may be used in combination.
  • inorganic ionic conductive materials such as sodium perchloric acid, calcium perchloric acid and sodium chloride
  • organic ionic conductive materials such as modified aliphatic dimethylethylammonium ethosulfate, stearyl ammonium acetate, lauryl ammonium acetate and octadecyltrimethylammonium perchlorate. Any one of these materials may be used, or a plurality of them may be used in
  • a blade 43 has its one end secured to the developer vessel 40 with a predetermined length, while the free end, not secured, is pressed onto the developing roller 41 with a predetermined pressure.
  • the one end of the blade 43 is secured to the developer vessel 40 in a manner so as to make itself contact the developing roller 41 by utilizing, for example, its own spring property.
  • the blade 43 which is a metal plate having a plate thickness of approximately 0.05 to 0.5 mm, is allowed to elastically distort in its inherent spring property, and comes into contact with the developing roller 41 with a predetermined pressure so that the toner layer 45 is regulated to a predetermined thickness with a predetermined quantity of static charge.
  • the tip portion of the blade 43 which contacts the developing roller 41, is subjected to a bending process so that it has a face that slightly tilts in a direction so as to widen the angle made by the developing roller 41 and the bent blade 43 as spaced from the surface of the developing roller 41.
  • the contact portion of the blade 43 with respect to the developing roller 41 is subjected to a coating process so as to adjust the quantity of toner static charge and suppress fusion in the toner.
  • a material having a spring property is used; for example, spring steels, such as SUS including stainless steel such as SUS301, SUS304, SUS420J2 and SUS631, and copper alloys, such as C1700, C1720, C5210 and C7701, may be used.
  • spring steels such as SUS including stainless steel such as SUS301, SUS304, SUS420J2 and SUS631, and copper alloys, such as C1700, C1720, C5210 and C7701, may be used.
  • the fine tilt face of the free end of the blade 43 is formed by a processing method in which: a chip-shaped tip portion, which has been preliminarily manufactured by mechanical cutting, grinding, a bending process or a molding process into a predetermined shape, is bonded by using a conductive bonding agent, etc., or the blade tip portion is subjected to a step-forming process and metal foil is bonded thereto by using a conductive bonding agent, etc.
  • the blade 43 when used, is basically made in contact with the developing roller 41 in the form of the above-mentioned member as it is. However, in some cases, coating is provided on the contact face with the developing roller 41 so as to stabilize the quantity of toner static charge and to suppress toner fixing.
  • the blade surface is spray-coated with a fluorine-containing resin or a graphite-containing resin, and after having been dried for not less than 30 minutes at approximately 80°C, this is baked for 30 minutes at 260°C, and then slightly ground with sand paper of #10000 so as to provide a film thickness of 8 to 12 ⁇ m; or aluminum formed on the blade surface is subjected to an anodic oxidation so as to provide an alumite coat thereon with a thickness of approximately 50 to 100 ⁇ m.
  • the reset member 44 is allowed to directly contact toner after a developing process, while being pressed onto the developing roller 41, so that it eliminates a static charge and separates the toner from the developing roller 41 so as to be reused.
  • a corona charger may be used to eliminate a static charge, or a rotary member for contact separation may be installed so as to separate the toner from the developing roller 41 so as to be reused.
  • a plate-shaped elastic member is used, and this is pressed onto the developing roller 41 with an appropriate pressure in the same manner as the blade 43, and allowed to static-eliminate and remove toner to be recovered after a developing operation, with a bias voltage Vd from the power-supply circuit 14 being supplied thereto. Therefore, with respect to a material for the elastic member, nylon, PET (polyethylene-terephthalate), a PTFE (polytetrafluoroethylene)-containing resin, or polyurethane, etc., is used; and an electric-resistance adjusting material is added to this serving as a base material (main component) so as to provide an appropriate electric resistance. A reset voltage Vd is supplied from the power supply 14 to the reset member 44 having such a resistance.
  • a furnace or channel black such as ISAF, HAF, GPF, SRF, etc., which has a nitrogen-adsorption specific surface area of not less than 20 m 2 /g to not more than 130 m 2 /g, is used, and not less than 10 parts by weight (in some cases, not more than 70 parts by weight) of this is blended to 100 parts by weight of polyurethane (or nylon, PET, or other resins in the same manner).
  • toner that is a non-magnetic one-component developer 10
  • a material which consists of 80 to 90 parts by weight of a styrene-acrylic copolymer and 5 to 10 parts by weight of carbon black or 0 to 5 parts by weight of a charge-control agent, is mixed, kneaded, pulverized and classified, thereby obtaining a negatively chargeable toner having an average particle size of 5 to 10 ⁇ m.
  • To this toner is internally or externally added 0.5 to 1.5 parts by weight of silica (SiO 2 ) so as to provide a better fluidity, thereby obtaining a non-magnetic one-component developer 10.
  • a positively chargeable toner may be obtained. This is easily achieved by appropriately select a binding resin as the main component, a charge-control agent, etc.
  • the present toner may also be applied to color toner used for color copying machines and printers.
  • the non-magnetic one-component developer which has any of the following compositions, may also be applied to the developing device of the present invention.
  • thermoplastic resin that forms the binding resin as a main component in addition to styrene-acrylic copolymer, a material such as polystyrene, polyethylene, polyester, low molecular polypropylene, epoxy, polyamide and polyvinylbutylal, may be used.
  • yellow dyes and pigments include benzidine yellow pigments, Phonon Yellow, anilide acetoacetate insoluble azo pigments, monoazo pigments, azomethine pigments, etc.; magenta dyes and pigments include xanthene magenta dyes, phosphor-tungsten-molybdenum acid lake pigments, anthraquinone dyes, coloring materials made of a xanthene dye and an organic carboxylic acid, Thioindigo, naphthol insoluble azo pigments, etc.; and cyan dyes and pigments include copper phthalocyanine pigments, etc.
  • toner fluidizing material besides silica as an externally added agent, materials such as colloidal silica, titanium oxide, alumina, zinc stearate and polyvinylidene fluoride, and a mixture of these may be used.
  • materials for negatively chargeable toners include azo metal-containing dyes, metal complex salts of organic acids, chlorinated paraffin, etc.
  • Materials for positively chargeable toners include nigrosine dyes, metal salts of fatty acids, amines, quaternary ammonium salts, etc.
  • the blade 43 which is pressed against the developing roller 41 is used to regulate the amount of adhesion of toner 10 to a constant layer thickness. Thereafter, the toner 10 develops an electrostatic latent image on the surface of the photoconductive member 1 that has been transported to the developing area.
  • bias voltages Va, Vc and Vb are supplied to the developing roller 41, the supply roller 42 and the blade 43 respectively.
  • the toner to be developed comes to have no smaller particle-size selectivity.
  • the toner particles shift in accordance with the bias electric field starting with those having a smaller particle size; therefore, at the portion that has developed a white image portion, the closer to the surface of the developing roller, the smaller the particle size, while at portions that have developed black image portions, hardly any fluctuation has occurred in the particle size since those portions have been refreshed by the developing process. Therefore, if residual toner 10, which remains on the developing roller 41 after a developing process, is not sufficiently removed from the developing roller 41, the toner average particle size is minimized.
  • the toner specific charge is inversely proportional to the particle size as shown in Fig. 14.
  • the greater the toner specific charge the flatter the developing gamma characteristic, as shown in Fig. 10. Therefore, at the portions having been subjected to the toner having smaller particle sizes in the toner average particle size, the specific charge increases, thereby causing a reduction in the amount of developing.
  • the particle-size reduction in the toner average particle size depends on image patterns as to whether a white image (non-colored image) is developed or a black image (colored image) is developed. Therefore, depending on image patterns, the specific charge varies, causing fluctuations in the amount of developing. This causes developing ghost images that are exerted by the influence of a previously developed image pattern on the next image, and tends to cause degradation in the image quality. In this case, the specific charge increases at the white portion due to the particle-size reduction, resulting in a reduction in the amount of developing, that is, so-called positive ghosts.
  • the thickness of a toner layer remaining on the developing roller 41 after a black image portion has been developed is very thin as compared with the thickness of a toner layer remaining on the developing roller 41 after a white image portion has been developed. Therefore, in the case of an insufficient toner supply by the supply roller 42 and the blade 43, the portion of the developing roller 41 at which a black image was previously developed has a less quantity of toner adhesion. With respect to the developing characteristic to the quantity of toner adhesion, the smaller the quantity of toner adhesion, the smaller the amount of developing as shown in Fig. 9. In this case, the amount of toner adhesion at a black image portion reduces due to an insufficient toner supply, thereby resulting in a reduction in the amount of developing, that is, so-called negative ghosts.
  • the thickness of a toner layer remaining on the developing roller 41 after a black image portion has been developed is very thin as compared with the thickness of a toner layer remaining on the developing roller 41 after a white image portion has been developed; therefore, the black image developing portion has a stronger electric field intensity even upon application of the same electric potential difference, with the result that it is highly susceptible to a toner dielectric breakdown and an over-current and a charge tends to be supplied to the surface of the developing roller.
  • Fig. 11 shows the relationship between the surface electric potential change ⁇ V and the amount of developing in the developing roller 41; and, for example, this graph clearly shows a characteristic in which as the surface electric potential rises, the developing bias increases with the result that the amount of developing increases.
  • the occurrence of developing ghost images is prevented by limiting the difference between the average particle size after developing a black image and the average particle size after developing a white image to a predetermined value range. Moreover, developing ghost images due to fluctuations in the amount of toner adhesion to the developing roller 41 and changes in the surface electric potential of the developing roller 41 are prevented by limiting the resistivities, applied bias voltages, etc. of the respective members so that a stable developing process is obtained.
  • a negatively chargeable photoconductive member was used as the photoconductive member 1 in the present embodiment.
  • it had a conductive base member having a diameter of 65 mm, and was charged to an electric potential of -550 V by a charger 2.
  • the photoconductive member 1 had its base member grounded, and was rotated at a peripheral speed of 190 mm/sec in the arrow direction.
  • the developing roller 41 was constituted by a stainless rotary shaft 41a having a diameter of 18 mm the surface of which was coated with a semiconductive elastic layer 46 having a thickness of 8 mm.
  • the developing roller 41 was constituted by the rotary shaft 41a that is conductive and the semiconductive elastic layer 46 that has a flexibility and is formed on the rotary shaft 41a.
  • the developing roller 41 was adjusted so that, supposing the resistivity of a portion thereof contacting the photoconductive member 1 through the one-component developer 10 is Rd [ ⁇ ], it satisfies 10 4 ⁇ Rd ⁇ 5 ⁇ 10 6 .
  • This adjustment was made by using the aforementioned resistance-adjusting base material with a rubber hardness of 65 to 70 degrees on the Asker C hardness standardized by SRIS (Standard Specification; Japan Rubber Association) and a surface roughness of 2 to 8 ⁇ m on Rz (ten-point average roughness) standardized by JISB0601. As illustrated in Fig. 1, the developing roller 41 was driven to rotate at a peripheral speed of 285 mm/sec in the arrow direction.
  • a voltage of -400 V was supplied to the stainless rotary shaft 41a of the developing roller 41 from a power-supply circuit 11 as a developing bias voltage Va, and the developing roller 41 was pressed onto the photoconductive member 1 with a developing nip width of 1.5 mm through a toner layer 45 on the surface of the developing roller 41.
  • the supply roller 42 it was constituted by a stainless rotary shaft the surface of which was coated with conductive urethane foam having a volume resistivity of 105 ( ⁇ cm) and a cell density of 80 to 100 number/inch.
  • the diameter of the supply roller 42 was set at 20 mm, and was allowed to contact the developing roller 41 with a contact depth of 0.5 mm. Then, the supply roller 42 was driven to rotate in the arrow direction at a peripheral speed of 170 mm/sec.
  • a voltage of -500 V was supplied to the stainless rotary shaft of the supply roller 42 by a power-supply circuit 12 as a bias voltage Vc.
  • the blade 43 used as a developer-layer regulating member, was formed by a stainless plate having a plate thickness of 0.1 mm, and pressed onto the developing roller 41.
  • the blade 43 which has a cantilever plate-spring structure, had its free end come into contact with the developing roller 41, and was elastically distorted so as to apply a predetermined pressure onto a toner layer formed on the surface of the developing roller 41.
  • a voltage of -500 was also applied to the blade 43 as a bias voltage (Vb) from a power-supply circuit 13.
  • the reset member 44 which is provided as a sheet-shaped elastic member formed by dispersing carbon in a resin base material, was designed to come into face-contact with the developing roller 41 with a predetermined pressure. A voltage of -300 V was also supplied to the reset member 44 as a reset bias voltage (Vd) by a power-supply circuit 14.
  • a uniform toner thin film 45 was formed on the developing roller 41, and the aforementioned contact inversion developing process was carried out on the photoconductive member 1.
  • the quantity of toner adhesion m/a was set at 0.5 to 0.8 mg/cm 2
  • the quantity of toner charge q/m was set at -10 to -20 ⁇ C/g
  • the thickness Dt of the toner layer was set at 10 to 30 ⁇ m.
  • Fig. 15 shows an image pattern used for evaluating developing ghost images, in which a black and white checker pattern is placed at the leading portion of an image corresponding the first rotation of the developing roller and a uniform half-tone pattern is placed at the succeeding portion of the image corresponding to the second rotation and thereafter of the developing roller. Evaluation on developing ghost images was made by visual observation and a Machbeth densitometer RD 918.
  • a broken line represents a volume particle-size distribution of toner possessed by a portion on the developing roller immediately after it has passed through the developing-layer regulating member.
  • the portion in question still had most of its toner remaining thereon after it had been subjected to a white-image developing process at the developing section, and is again rotated to pass through the developer-layer regulating member.
  • the volume-average particle size Dbk of the black portion is 7.6 ⁇ m which is virtually the same as the toner volume-average particle size inside the developer vessel.
  • the volume-average particle size Dwt of the white portion is 4.8 ⁇ m which has been greatly reduced in particle-size.
  • the specific charge was -10 ⁇ C/g at the black portion, and -14 ⁇ C/g at the white portion. Thus, it was confirmed that the specific charge increases as the particle size reduces.
  • the above-mentioned developing ghost evaluation pattern was developed under these conditions, positive ghosts were observed.
  • a solid line represents a volume particle-size distribution of toner possessed by a portion on the developing roller immediately after it has passed through the developer-layer regulating member.
  • the portion in question lost most of its toner when it was subjected to a black-image developing process at the developing section, and is again rotated to pass through the developer-layer regulating member.
  • a broken line represents a volume particle-size distribution of toner possessed by a portion on the developing roller immediately after it has passed through the developing-layer regulating member.
  • the portion in question still had most of its toner remaining thereon after it had been subjected to a white-image developing process at the developing section, and is again rotated to pass through the developer-layer regulating member.
  • the volume-average particle size Dbk of the black portion is 7.6 ⁇ m which is virtually the same as the toner volume-average particle size inside the developer vessel.
  • the volume-average particle size Dwt of the white portion is 6.1 ⁇ m, which shows that the particle-size reduction has been suppressed as compared with the case without a reset member.
  • the specific charge was -10 ⁇ C/g at the black portion, and -11 ⁇ C/g at the white portion. Thus, it was confirmed that the fluctuations in the specific charge become smaller.
  • the above-mentioned developing ghost evaluation pattern was developed under these conditions, no positive ghosts were observed.
  • optical density evaluation obtained by a Machbeth densitometer and visual observation were used in a combined manner.
  • the optical densities of the white portion and the black portion of a developing ghost image of the black and white checker pattern appearing on the half-tone portion were measured, and the rate of residual ghost was calculated based on the following expression (3): ⁇ (ghost black-portion density) ⁇ - ⁇ (ghost white-portion density ⁇ ⁇ (ghost black-portion density) ⁇ + ⁇ (ghost white-portion density ⁇ ⁇ 100 [%]
  • the rate of residual ghost images obtained by the above expression 3 is not less than 3 %, it is judged that image ghosts exist, and if the rate is not more than 1 %, it is judged that no ghost images exist. If the rate is in the range from 1 to 3 %, a judgement as to whether or not ghost images exist was made by visual observation.
  • the developing device 4 of the present embodiment has the same arrangement as the developing device 4 of the above-mentioned embodiment 1 except that the reset member 44 is omitted.
  • the developing device 4 of the present embodiment has an arrangement which can prevent developing ghost images caused by fluctuations in the volume particle size by improving the distribution of toner volume particle sizes, even if the reset member is omitted.
  • the CV value (Coefficient of Variation) [%] as defined by the following equation 5 is used as an index for indicating the sharpness of the distribution of the volume particle sizes of the toner.
  • CV 100 ⁇ (Standard deviation/Average value)
  • the above-mentioned CV value and the toner layer thickness exert their synergistic effect so as to suppress the occurrence of developing ghost images, and it is easily predict that, for example, even when the toner layer thickness exceeds three times the volume average particle size of the toner layer thickness, it is possible to prevent the occurrence of developing ghost images by reducing the CV value to not more than 25 %.
  • the same is true for the synergistic effect with the reset member 44.
  • bias voltages are supplied to the developing roller 41 and various members placed on the periphery of the developing roller 41, that is, the supply roller 42, the blade 43 and the reset member 44.
  • a conventional developing device which has higher resistivities in the above-mentioned parts, is less susceptible to a discharge due to the bias voltages; however, in the developing device of the present invention, since all the above-mentioned parts are constituted by low-resistance materials, it is necessary to determine the upper limit values of the bias voltages applied to the respective members.
  • Fig. 5 is a drawing that explains a method for measuring the resistivity Rt of the toner layer 45 between the developing roller 41 and the photoconductive member 1.
  • the static resistivity (Rt) of the toner layer 45 was measured by using the above-mentioned method, and the results of the measurements were plotted as the voltage-current characteristic of the toner layer 45 as shown in Fig. 6.
  • the current of the toner layer thus measured exhibits a comparatively linear characteristic at a low voltage section, and shows that it has an over-current flow abruptly when it reaches a certain value Vth (V).
  • Vth corresponds to a discharge starting voltage at which an aerial discharge or a creeping discharge occurs between the toner particles.
  • the resistivity found from equation (6) based upon current values measured by using voltages in this range, is defined as the static resistivity Rt of the toner layer 45.
  • Table 2 shows the results of measurements that were made on the toner layer resistivity Rt [M ⁇ ] of several kinds based upon the measuring method as shown in Fig. 5.
  • the developing bias voltage Va, the bias voltage Vc, the bias voltage Vb and voltage Vd are respectively applied to the developing roller 41, the supply roller 42, the blade 43 and the reset member 44.
  • the respective bias voltages are preferably set so that the absolute value of the difference between the developing bias voltage Va supplied to the developing roller 41 and each of the bias voltages supplied to the supply roller 42, the blade 43 and the reset member 44 is set at not more than the above-mentioned value, 20 ⁇ T[V].
  • Fig. 11 shows a developing characteristic in which the amount of change in the surface potential ⁇ V on the developing roller 41 is used as a parameter; and as the electric potential on the surface of the developing roller 41 increases, the graph shifts to the left. Therefore, when consideration is given to a portion of the graph at approximately 100 V, that is, a half-tone developing potential, it is noted that the higher the electric potential on the surface of the developing roller 41, the greater the amount of developing.
  • the surface potential of the developing roller 41 increases. It is dependent on the relationship of sizes between the time constant determined by the resistivity and the static capacitance of the developing roller and the process rate whether or not the surface electric potential of the developing roller 41 increases.
  • the developing roller 41 used in the developing device of the present invention has a low resistivity, the time constant is small, and in the case of a peripheral velocity of approximately 285 mm/s of the developing roller 41, it is less likely to have the occurrence of developing ghost images due to a charge accumulated on the surface of the developing roller.
  • a similar phenomenon of changes in the surface electric potential of the developing roller 41 occurs in the toner supplying section, the layer regulating section or the reset section, degradation in the image quality might occur.
  • the rotation speed of the supply roller is determined by selecting the peripheral velocity ratio between it and the developing roller in a range approximately from 0.5 to 2.0.
  • the value of the resistivity is determined by the contact nip area, which is determined by the pressing force onto the developing roller and the sponge hardness, and the volume resistivity. The results of experiments carried out by changing these conditions show that the above-mentioned changes in the surface electric potential of the developing roller 41 do not occur if the value of the resistivity is set at not more than 10 k ⁇ .
  • the blade 43 when a blade of a metal plate spring is used as the blade 43 for regulating the toner layer, no change in the electric potential occurs on the blade surface in principle. However, in the case of coating with a resin material, etc., having a high electric resistance and an application of a conductive sheet, a potential change occurs, thereby greatly impairing the uniformity of the toner layer 45. Since the blade 43 is a stationary member, whether the surface potential changes or not is determined by the charge accumulating rate of the member and the time constant.
  • the reset member 44 is preferably made of a metal material or a low-resistivity material which allows a portion thereof contacting the developing roller 41 through the developer to have a resistivity of not more than 10 k ⁇ .
  • the problem of non-uniformity due to a voltage drop occurs in the same manner as the above-mentioned blade 43 made of the conductive sheet; however, this problem can be solved by making the width of the electrode 44a (conductor electrode) of the reset member 44 longer than the image effective width as illustrated in Fig. 18.
  • the developing roller 41 is placed on a metal detection electrode 104 installed on an insulating flat plate 103, and a load F is applied onto both of the ends of the shaft 41a of the developing roller 41.
  • a constant voltage is supplied to the shaft 41a of the developing roller 41 from a power supply 106, and a current flowing through the detection electrode 104 is measured by an ampere meter 102.
  • Rb electrical resistance
  • the average value of measured values obtained at several points in the circumferential direction is defined as the central value of the value of resistivity of the developing roller 41.
  • the outer diameter of the developing roller was ⁇ 34
  • the thickness Dd of the resistance layer was 8 mm
  • the length in the axis direction was 320 mm
  • Fig. 8 shows a developing characteristic in which the value of resistivity of the developing roller 41 is used as a parameter; and this indicates that the developing gamma changes to a great degree around a point exceeding 5 ⁇ 10 6 ⁇ .
  • the upper limit of the value of resistivity of the developing roller which can maintain superior image quality is regarded as 5 ⁇ 10 6 ⁇ .
  • the values of resistivity as shown in Table 3 are values obtained under the standard measuring environments in accordance with JISZ-8703; however, for example, under high-temperature, high-moisture environments of 35°C and 85% RH (Relative Humidity) or low-temperature, low-moisture environments of 5°C and 20% RH, the value of resistivity tends to change, with the result that the developing characteristics tend to change greatly.
  • urethane resins are preferably used as the material thereof; however, as a result of measurements of the moisture absorption rate and the value of resistivity based upon method JISK-7209A, it is found that in the case of a urethane base member having a moisture absorption rate of 2 to 5 %, the value of resistivity varies by one digit or two digits between high temperature, high moisture environments and low temperature, low moisture environments.
  • the value of resistivity only varies by 0.5 to one digit, and it is less susceptible to fluctuations in the amount of developing due to the variations in the value of resistivity, and makes it possible to maintain good image quality.
  • the value of resistivity of the toner layer 45 was regulated in order to provide a method for preventing an over-current that occurs in the case of the application of a developing roller 41 having a low electrical resistance. Moreover, any over-current was prevented by regulating the thickness of the toner layer so as to provide a good developing process. Furthermore, any over-current was also prevented by regulating the bias voltages to be supplied through various members that contact the developing roller 41 as well as the differences between the bias voltages.
  • the toner layer might be impaired due to an unexpected reason such as foreign matter included into the developing device, and this might cause an over-current.
  • the developing device 4 of the present embodiment is provided with an over-current protective function which will be described below.
  • a voltage source 51 which represents an electric potential difference between the developing bias voltage Va supplied to the developing roller 41 and the bias voltage Vd supplied to the reset member 44, a semiconductive layer resistor Rd of the developing roller 41, a toner layer resistor Rt, a resistor Re of the reset member 44 and a protective resistor 50 are connected in series with one another.
  • the value of resistivity Rd of the developing roller 41 and the value of resistivity Re of the reset member 44 are set so as to be sufficiently lower than the value of resistivity Rt of the toner layer, and most of the bias voltage 51 to be supplied is normally applied to the toner layer 45, with the result that the value of a current flowing therethrough is minute.
  • the toner layer is impaired and the value of resistivity Rt of the toner layer becomes apparently low, if no over-current protective resistor 50 is provided, an over-current flows since the entire resistance is low, thereby causing toner fusion and damages to the developing roller 41 and the reset member 44.
  • the value of resistivity of the protective resistor 50 is set as great as possible.
  • the value of resistivity of the protective resistor 50 is too great, a voltage that is supplied by the toner layer 45 and the protective resistor 50 in a normal state tends to be divided, with the result that the voltage applied to the toner layer 45 becomes smaller due to a voltage drop caused by the protective resistor 50.
  • the bias voltage (Vd) is no longer applied to the reset member 44 in a manner as originally expected.
  • the upper limit of the value of resistivity of the protective resistor 50 has to be regulated. The following description will discuss an appropriate value on the upper limit of the value of resistivity of the over-current protective resistor 50.
  • Fig. 12 an explanation is given of a construction in which the protective resistor 50 is only installed between the reset member 44 and the power-supply circuit 14; and the same protective resistor as the resistor 50 may be inserted between the supply roller 42 and the power-supply circuit 12 as well as between the reset member 43 and the power-supply circuit 13, if necessary.
  • a developing current Id (A), generated by the charged toner being transferred from the developing roller 41 to the photoconductive member 1, is calculated from the following equation (7).
  • Id q/m ⁇ m/a ⁇ l ⁇ v
  • the amount of adhesion of toner is 1.0 mg/cm 2
  • the toner specific charge is -20 ⁇ C/g
  • the effective image width is 300 mm
  • the peripheral velocity of the photoconductive member 1 is 190 mm/sec
  • the absolute value of the developing current is 11. 4 ⁇ A based upon the above-mentioned equation (7).
  • This current value at the time of the full solid-black developing process forms a maximum value in the developing current.
  • the developing current Id is generated by the toner transfer at the developing section (the area at which the developing roller 41 and the photoconductive member 1 come into contact with each other); and this is also true for the supply roller 42, the blade 43 and the reset member 44 that come into contact with the developing roller 41.
  • Vr Ir ⁇ Rr
  • the upper limit value (Rr) of the protective resistor 50 is determined by a degree to which the voltage drop due to the toner transfer current is permitted in a regular state.
  • the lower limit value (Rr) of the respective protective resistors 50 is determined by a degree to which the over-current at the time of an abnormal event is permitted.
  • toner specific charge for practical use is in the range of -5 to -30 ⁇ C/g, and more preferably, -10 to -20 ⁇ C/g, in the case of negatively chargeable toners.
  • the amount of toner adhesion on the photoconductive member 1 required for a solid black copy is approximately 1.0 mg/cm 2 , although this value slightly changes depending on the masking property of toners.
  • the maximum transfer current Imax [ ⁇ A] is represented by the following equation (9) after substitution of -30 ⁇ C for the specific charge and 1.0 mg/cm 2 for the amount of adhesion in equation (7).
  • Imax 300 ⁇ 1 ⁇ v
  • the lower limit value Rmin (M ⁇ ) of the protective resistor 50 is represented as follows based upon equations 8 and 9.
  • Rmin V/(300 ⁇ n ⁇ l ⁇ v)
  • V represents a difference between a bias voltage supplied to the developing roller 41 and a surface electric potential of the photoconductive member 1 in contact with the developing roller 41 as shown in Fig. 13.
  • the minimum values Rmin of over-current protective resistors to be inserted in the reset member 44, the supply roller 42 and the blade 43 are found by substituting "5" or “10” for "n” in the above-mentioned equation (10).
  • "V” in equation (10) represents a difference between the developing bias voltage (Va) and the reset bias voltage (Vd) in the reset member 44, a difference between the developing bias voltage and the supply bias voltage (Vc) in the supply roller 42, and a difference between the developing bias voltage and the regulating bias voltage (Vb) in the blade 43.
  • the maximum value of the transfer current in the toner layer was found based on the fact that the maximum value of the toner specific charge for practical use is 30 ⁇ C/g and that the amount of toner adhesion on the photoconductive member 1 required for a solid black copy is approximately 1.0 mg/cm 2 .
  • the supply roller 42 has functions by which toner on the surface of the developing roller 41 is removed after a developing process and toner inside the developing vessel 40 is charged and applied onto the developing roller 41. For this reason, the removing mechanism of toner from the developing roller 41 after a developing process requires a reversed current, with the result that the maximum current at the developing position becomes smaller than the maximum developing current.
  • the blade 43 Since toner has preliminarily been applied to the surface of the developing roller 41 by the supply roller 42, the blade 43 is hardly subjected to toner transfer; therefore, it is considered to be mostly subjected to the toner charging current. Therefore, its maximum current is smaller than the maximum developing current in the developing section. The results of actual measurements with respect to the current flowing through the blade 43 show that it is not more than 1/3 of the maximum developing current.
  • the upper limit value Rmax ( ⁇ ) of the protective resistor in the blade 43 (developer-layer regulating member) and the reset member 44 is defined by the following equation (12) based upon equations (8) and (9).
  • the protective resistors R4, R2 and R3, which are inserted between the developing roller 41 and the power supply circuits 14, 12 and 13 that respectively apply bias voltages to the reset member 44, the supply roller 42 and the blade 43 have respective values represented as follows:
  • the developing current fluctuates due to fluctuations in the amount of development caused by the black-and-white ratio of an image. Consequently, the amount of a voltage drop in the developing roller 41 section is varied by the black-and-white ratio. This results in conspicuous density irregularities due to the black-and-white ratio particularly in half-tone images.
  • the developing device 4 of the present embodiment adopts a developing roller 41 with a low resistivity, and inserts a resistor 50 between the reset member 44 and the power supply circuit 14 as illustrated in Fig. 12, without inserting a resistor between the developing roller 41 and the power supply circuit 11. Moreover, after experimental studies made on the maximum electric potential difference applied onto the toner layer 45 in the developing section, it is confirmed that setting of not more 400 V makes it possible to avoid the possibility of any over-current against the photoconductive member 1.
  • the protective resistors are inserted between the reset member 44, the supply roller 42 and the blade 43 and the power supply circuits 14, 12 and 13 for supplying voltages to the respective members; thus, it becomes possible to prevent any over-current even if the above-mentioned electric potential difference is increased, to widen the range of setting of the protective resistors, to eliminate the occurrence of an over-current, and consequently to provide a superior developing process.
  • the developing bias voltage (Va) is supplied so that the electric potential difference at the developing section that contacts the photoconductive member 1 is set at not more than 400 V; this makes it possible to prevent any over-current, and to achieve a stable developing process.
  • the developing device of the present invention which develops an electrostatic latent image on the electrostatic-latent image bearing body (photoconductive member 1), is provided with a developer-bearing body (developing roller 41) which bears one-component developer (toner) on its surface and develops the electrostatic latent image by contacting the electrostatic-latent-image bearing body, a developer-supplying member (supply roller 42) for supplying developer to the developer-bearing body, and a developer-layer regulating member (blade 43) which contacts the developer-bearing body so as to regulate the layer thickness of the developer that has been supplied by the developer-supplying member, and supposing that the volume-average particle size of the developer is Dbk, the developer at this time being maintained on the developer-bearing body as a layer that has been supplied by the developer-supplying member and again formed so as to have a predetermined thickness by the developer-layer regulating member after the developer-bearing body, on which the developer was formed as a layer having a predetermined
  • the developing device is preferably arranged so that supposing that the film thickness of the one-component developer maintained on the developer-bearing body is T [ ⁇ m] and that the volume-average particle size is D [ ⁇ m], T ⁇ 3 ⁇ D is satisfied.
  • a reset member 44 which contacts the developer-bearing body after the developer-bearing body and the electrostatic-latent-image bearing body came into contact with each other, may be adopted.
  • the developing device of the present invention is preferably designed so that supposing that a voltage applied to the developer-bearing body (developing roller 41) is Va [V] and a voltage applied to the reset member 44 is Vd [V], the voltages are preferably applied in a manner so as to make the sign of Va - Vd identical to the charging polarity of the developer.
  • the voltages are preferably applied in a manner so as to make the sign of Va - Vb reversed to the charging polarity of the developer.
  • the voltages are preferably applied in a manner so as to make the sign of Va - Vc reversed to the charging polarity of the toner.
  • the above-mentioned reset member may be provided as a rotating member of a contact-separating type (conductive roller) that is installed so as to contact the developer-bearing body.
  • a contact-separating type conductive roller
  • the reset member is formed by the rotating member of a contact-separating type such as a conductive roller, it becomes possible to achieve a developing device with longer service life.
  • the developing device of the present invention also makes it possible to eliminate developing image ghosts due to fluctuations in the surface electric potential, for example, by providing the following arrangements.
  • the developer-bearing body (developing roller 41) is preferably constituted by a conductive shaft (rotary shaft 41a) and a flexible semiconductive layer 46 formed on the conductive shaft, and designed so that supposing that the resistivity at a position allowing the developer-bearing body to contact the electrostatic latent-image bearing body through the developer is Rd [ ⁇ ], 10 4 ⁇ Rd ⁇ 5 ⁇ 10 6 is satisfied.
  • the semiconductive layer on the developer-bearing body is preferably made of a urethane resin having a moisture absorption rate of not more than 1 %.
  • the urethane resin having a moisture absorption rate of not more than 1 % is used as the semiconductive layer on the developing roller 41, it becomes possible to minimize fluctuations in the value of resistivity due to fluctuations in temperature and moisture, and also to prevent contamination to the electrostatic latent-image bearing body as well as effectively preventing degradation in the image quality.
  • the members such as the reset member 44 and the supply roller 42 are preferably made of a low resistivity material so that the resistivity is set to not more than 10 k ⁇ at a portion thereof contacting the developing roller 41 through a metal material or the developer.
  • the reset member 44 or the developer-layer regulating member (blade 43) is preferably constituted by a thin plate member made of a low resistivity material, a conductor electrode (electrode 44a, electrode 43a) that is formed with a width virtually not less than the effective image width on the surface other than the contact portion with the toner layer 45 of the thin plate member and a voltage applying means (power supply 14, power supply 13) for applying a voltage to the conductor electrode.
  • the developing device is preferably designed so that supposing that a voltage applied to the developer-bearing body is Va [V] and a voltage applied to the reset member is Vd [V], and supposing that the one-component developer maintained on the electrostatic-latent-image bearing body has a layer thickness of T [ ⁇ m], an inequality,
  • the developing device is preferably designed so that supposing that a voltage applied to the developer-bearing body is Va [V] and a voltage applied to the developer-supplying member is Vc [V] , and supposing that the one-component developer maintained on the electrostatic-latent-image bearing body has a layer thickness of T [ ⁇ m], 2 an inequality,
  • the developing device is preferably designed so that supposing that a voltage applied to the developer-bearing body is Va [V] and a voltage applied to the developer-layer regulating member is Vb [V], and supposing that the one-component developer maintained on the electrostatic-latent-image bearing body has a layer thickness of T [ ⁇ m], an inequality,
  • the blade or the reset member which contacts the developing roller at not more than the above-mentioned value, 20 ⁇ T[V], in accordance with the thickness T of the toner layer, it becomes possible to prevent degradation in the developing operation due to a dielectric breakdown of the toner layer.
  • the developing device of the present invention is preferably designed so as to include a voltage-applying means for applying a voltage to the reset member and an over-current protecting resistor connected between the reset member and the voltage-applying means, in which, supposing that a voltage applied to the developer-bearing body is Va [V] and a voltage applied to the reset member is Vd [V] and supposing that the peripheral velocity of the electrostatic-latent-image bearing body is v [m/s] and the effective width of the developer-bearing body is l [m], the resistivity R4 [M ⁇ ] of the resistor satisfies an inequality,
  • the developing device of the present invention is preferably designed so as to include a voltage-applying means for applying a voltage to the developer-supplying member and an over-current protecting resistor connected between the developer-supplying member and the voltage-applying means, in which, supposing that a voltage applied to the developer-bearing body is Va [V] and a voltage applied to the developer-supplying member is Vc [V] and supposing that the peripheral velocity of the electrostatic-latent-image bearing body is v [m/s] and the effective width of the developer-bearing body is l [m], the resistivity R2 [M ⁇ ] of the resistor satisfies an inequality,
  • the developing device of the present invention is also preferably designed so as to include a voltage-applying means for applying a voltage to the developer-layer regulating member and an over-current protecting resistor (protective resistor 50) connected between the developer-layer regulating member and the voltage-applying means, in which, supposing that a voltage applied to the developer-bearing body is Va [V] and a voltage applied to the developer-layer regulating member is Vb [V] and supposing that the peripheral velocity of the electrostatic-latent-image bearing body is v [m/s] and the effective width of the developer-bearing body is l [m], the resistivity R3 [M ⁇ ] of the resistor satisfies an inequality,
  • the semiconductive layer of the developing roller so as to have a resistivity of not more than 10 7 ⁇ .
  • the developing device since the lower limit of the value of resistivity in the toner layer is regulated, it becomes possible to improve the safety against a dielectric breakdown of the toner layer and over-currents even when a bias voltage is applied to each of the members, and consequently to realize stable toner-layer forming and developing characteristics.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Dry Development In Electrophotography (AREA)
  • Developing For Electrophotography (AREA)
  • Developing Agents For Electrophotography (AREA)

Claims (23)

  1. Entwicklungsvorrichtung zum Entwickeln eines elektrostatischen latenten Bilds auf einem Haltekörper (1) für das elektrostatische latente Bild, umfassend:
    einen Entwickler-Haltekörper (41), der einen Einkomponenten-Entwickler (10) auf einer Oberfläche davon hält und das elektrostatische latente Bild durch ein Kontaktieren des Haltekörpers (1) für das elektrostatische latente Bild entwickelt;
    ein Entwickler-Zuführungselement (42) zum Zuführen von Entwickler (10) zu dem Entwickler-Haltekörper (41); und
    ein Entwicklerschicht-Regelelement (43), das den Entwickler-Haltekörper (41) kontaktiert, um so eine Schichtdicke des Entwicklers zu regeln, der von dem Entwickler-Zuführungselement (42) zugeführt worden ist,
    wobei, unter der Annahme, dass der Entwickler (10) eine volumengemittelte Teilchengröße aufweist, die durch Dbk dargestellt ist, wobei der Entwickler (10) zu dieser Zeit auf dem Entwickler-Haltekörper (41) als eine Schicht, die von dem Entwickler-Zuführungselement (42) zugeführt worden ist, gehalten und, um so eine vorbestimmte Dicke aufzuweisen, von dem Entwicklerschicht-Regelelement (43) wieder gebildet wird, nachdem der Entwickler-Haltekörper (41), auf welchem der Entwickler (10) als eine Schicht gebildet wurde, die eine vorbestimmte Dicke aufweist, einen Farbbild-Entwicklungsprozess ausführte, und
    unter der Annahme, dass der Entwickler (10) eine volumengemittelte Teilchengröße aufweist, die durch Dwt dargestellt ist, wobei der Entwickler (10) zu dieser Zeit auf dem Entwickler-Haltekörper (41) als eine Schicht, die von dem Entwickler-Zuführungselement (42) zugeführt worden ist, gehalten und, um so eine vorbestimmte Dicke aufzuweisen, von dem Entwicklerschicht-Regelelement (43) wieder gebildet wird, nachdem der Entwickler-Haltekörper (41), auf welchem der Entwickler (10) als eine Schicht gebildet wurde, die eine vorbestimmte Dicke aufweist, einen Nicht-Farbbild-Entwicklungsprozess ausführte, eine Ungleichheit Dwt/Dbk > 0,8 erfüllt ist,
    wobei Dwk die volumengemittelte Teilchengröße eines schwarzen Gebiets des Entwickler-Haltekörpers (41) bezeichnet, welchem Entwickler von dem Entwickler-Zuführungselement (42) zugeführt wurde, und welches das Entwicklerschicht-Regelelement (43) passierte, wobei das schwarze Gebiet in der vorhergehenden Entwicklung verwendet worden ist, um ein schwarzes Gebiet des latenten Bilds auf dem Bildhaltekörper (1) zu entwickeln, und
    wobei Dwt die volumengemittelte Teilchengröße eines weißen Gebiets des Entwickler-Haltekörpers (41) bezeichnet, welchem Entwickler von dem Entwickler-Zuführungselement (42) zugeführt wurde, und welches das Entwicklerschicht-Regelelement (43) passierte, wobei das weiße Gebiet in der vorhergehenden Entwicklung verwendet worden ist, um ein weißes Gebiet des latenten Bilds auf dem Bildhaltekörper (1) zu entwickeln.
  2. Entwicklungsvorrichtung nach Anspruch 1, dadurch gekennzeichnet, dass der Einkomponenten-Entwickler (10) einen CV-Wert [%] von nicht mehr als 25% aufweist, wobei der CV-Wert als CV = 100 × (Standardabweichung/Mittelwert) definiert ist, um so eine Verteilung in volumengemittelten Teilchengrößen darzustellen.
  3. Entwicklungsvorrichtung nach Anspruch 2, dadurch gekennzeichnet, dass, unter der Annahme, dass der Einkomponenten-Entwickler (10), der auf dem Entwickler-Haltekörper (1) gehalten wird, eine Filmdicke von T [µm] und eine volumengemittelte Teilchendichte von D [µm] aufweist, T < 3 × D erfüllt ist.
  4. Entwicklungsvorrichtung nach einem der Ansprüche 1 bis 3, weiter umfassend: Ein Rücksetzelement (44), das den Entwickler-Haltekörper (41) kontaktiert, nachdem der Entwickler-Haltekörper (41) und der Haltekörper (1) für das elektrostatische latente Bild in Kontakt miteinander kamen, um so den Entwickler (10) zu beseitigen, der auf dem Entwickler-Haltekörper (41) zurückbleibt.
  5. Entwicklungsvorrichtung nach Anspruch 4, dadurch gekennzeichnet, dass, unter der Annahme, dass eine Spannung, die an den Entwickler-Haltekörper (41) angelegt ist, Va [V] ist und eine Spannung, die an das Rücksetzelement (44) angelegt ist, Vd [V] ist, die Spannungen auf eine Weise angelegt werden, um so ein Vorzeichen von Va - Vd identisch zu einer Ladungspolarität des Entwicklers auszuführen.
  6. Entwicklungsvorrichtung nach Anspruch 4 oder Anspruch 5, dadurch gekennzeichnet, dass das Rücksetzelement (44) aus einem Metallmaterial ausgeführt ist.
  7. Entwicklungsvorrichtung nach Anspruch 4 oder Anspruch 5, dadurch gekennzeichnet, dass das Rücksetzelement (44) aus einem Material eines niedrigen Widerstandswerts ausgeführt ist, um so einen Widerstandswert von nicht mehr als 10 kΩ an einem Abschnitt davon aufzuweisen, der den Entwickler-Haltekörper (41) durch den Entwickler (10) kontaktiert.
  8. Entwicklungsvorrichtung nach Anspruch 7, dadurch gekennzeichnet, dass das Rücksetzelement (44) umfasst:
    Ein dünnes Plattenelement, das aus dem Material eines niedrigen Widerstandswerts ausgeführt ist;
    eine Leiterelektrode (44a), die auf einer Oberfläche der dünnen Platte an einem anderen Abschnitt als einem Kontaktabschnitt mit der Entwicklerschicht (45) gebildet ist,
    wobei die Leiterelektrode eine Breite nicht geringer als eine effektive Bildbreite aufweist; und
    eine Spannungsanlegungseinrichtung (14) zum Anlegen einer Spannung an die Leiterelektrode (44a).
  9. Entwicklungsvorrichtung nach Anspruch 4 oder Anspruch 5, dadurch gekennzeichnet, dass das Rücksetzelement (44) ein Drehelement eines Kontakttrennungstyps ist, das in Kontakt mit dem Entwickler-Haltekörper (41) angebracht ist.
  10. Entwicklungsvorrichtung nach einem der Ansprüche 4 bis 9, dadurch gekennzeichnet, dass, unter der Annahme, dass eine Spannung, die an den Entwickler-Haltekörper (41) angelegt ist, Va [V] ist und eine Spannung, die an das Rücksetzelement (44) angelegt ist, Vd [V] ist, und unter der Annahme, dass der Einkomponenten-Entwickler (10), der auf dem Haltekörper (1) für das elektrostatische latente Bild gehalten wird, eine Schichtdicke von T [um] aufweist, eine Ungleichheit |Va - Vd| ≤ 20 × T erfüllt ist.
  11. Entwicklungsvorrichtung nach einem der Ansprüche 1 bis 10, dadurch gekennzeichnet, dass, unter der Annahme, dass eine Spannung, die an den Entwickler-Haltekörper (41) angelegt ist, Va [V] ist und eine Spannung, die an das Entwicklerzuführungselement (42) angelegt ist, Vc [V] ist, und unter der Annahme, dass der Einkomponenten-Entwickler (10), der auf dem Haltekörper (1) für das elektrostatische latente Bild gehalten wird, eine Schichtdicke von T [µm] aufweist, eine Ungleichheit |Va - Vc| ≤ 20 × T erfüllt ist.
  12. Entwicklungsvorrichtung nach einem der Ansprüche 1 bis 11, dadurch gekennzeichnet, dass, unter der Annahme, dass eine Spannung, die an den Entwickler-Haltekörper (41) angelegt ist, Va [V] ist und eine Spannung, die an das Entwicklerschicht-Regelelement (43) angelegt ist, Vb [V] ist, und unter der Annahme, dass der Einkomponenten-Entwickler (10), der auf dem Haltekörper (1) für das elektrostatische latente Bild gehalten wird, eine Schichtdicke von T [µm] aufweist, eine Ungleichheit |Va - Vb| ≤ 20 × T erfüllt ist.
  13. Entwicklungsvorrichtung nach einem der Ansprüche 4 bis 12, weiter umfassend:
    Eine Spannungsanlegungseinrichtung (14) zum Anlegen einer Spannung an das Rücksetzelement (44), und
    einen Überstrom-Schutzwiderstand (50), der zwischen dem Rücksetzelement (44) und der Spannungsanlegungseinrichtung (14) angeschlossen ist.
  14. Entwicklungsvorrichtung nach Anspruch 13, dadurch gekennzeichnet, dass, unter der Annahme, dass eine Spannung, die an den Entwickler-Haltekörper (41) angelegt ist, Va [V] ist, und eine Spannung, die an das Rücksetzelement (44) angelegt ist, Vd [V] ist, und unter der Annahme, dass eine Umfangsgeschwindigkeit des Haltekörpers (1) für das elektrostatische latente Bild v [m/s] ist und eine effektive Breite des Entwickler-Haltekörpers (41) l [m] ist, der Widerstand einen Widerstandswert R4 [MΩ] aufweist, der eine Ungleichheit |Vd - Va|/(3000 × v × l) < R4 < 3,6/(l × v) erfüllt.
  15. Entwicklungsvorrichtung nach einem der Ansprüche 1 bis 14, weiter umfassend:
    Eine Spannungsanlegungseinrichtung (12) zum Anlegen einer Spannung an das Entwicklerzuführungselement (42); und
    einen Überstrom-Schutzwiderstand (50), der zwischen dem Entwickler-Zuführungselement (42) und der Spannungsanlegungseinrichtung (12) angeschlossen ist.
  16. Entwicklungsvorrichtung nach Anspruch 15, dadurch gekennzeichnet, dass, unter der Annahme, dass eine Spannung, die an den Entwickler-Haltekörper (41) angelegt ist, Va [V] ist, und eine Spannung, die an das Entwickler-Zuführungselement (42) angelegt ist, Vc [V] ist, und unter der Annahme, dass eine Umfangsgeschwindigkeit des Haltekörpers (1) für das elektrostatische latente Bild v [m/s] ist und eine effektive Breite des Entwickler-Haltekörpers l [m] ist, der Widerstand einen Widerstandswert R2 [MΩ] aufweist, der eine Ungleichheit |Vc - Va|/(1500 × v × l) < R2 < 6/(l × v) erfüllt.
  17. Entwicklungsvorrichtung nach einem der Ansprüche 1 bis 16, weiter umfassend:
    Eine Spannungsanlegungseinrichtung (13) zum Anlegen einer Spannung an das Entwicklerschicht-Regelelement (43); und
    einen Überstrom-Schutzwiderstand (50), der zwischen dem Entwicklerschicht-Regelelement (43) und der Spannungsanlegungseinrichtung (13) angeschlossen ist.
  18. Entwicklungsvorrichtung nach Anspruch 17, dadurch gekennzeichnet, dass, unter der Annahme, dass eine Spannung, die an den Entwickler-Haltekörper (41) angelegt ist, Va [V] ist und eine Spannung, die an das Entwicklerschicht-Regelelement (43) angelegt ist, Vb [V] ist, und unter der Annahme, dass eine Umfangsgeschwindigkeit des Haltekörpers (1) für das elektrostatische latente Bild v [m/s] ist und eine effektive Breite des Entwickler-Haltekörpers l [m] ist, der Widerstand einen Widerstandswert R3 [MΩ] aufweist, der eine Ungleichheit |Vb - Va|/(1500 × v × l) < R3 < 3,6/(l × v) erfüllt.
  19. Entwicklungsvorrichtung nach einem der Ansprüche 1 bis 18, dadurch gekennzeichnet, dass der Entwickler-Haltekörper einschließt:
    Eine leitfähige Welle (41a) und eine flexible halbleitende Schicht (46), die auf der leitfähigen Welle (41a) gebildet ist, und dass unter der Annahme, dass ein Widerstandswert an einer Position, die es zulässt, dass der Entwickler-Haltekörper (41) den Haltekörper (1) für das elektrostatische latente Bild durch den Entwickler (10) kontaktiert, Rd [Ω] ist, 104 < Rd < 5 × 106 erfüllt ist.
  20. Entwicklungsvorrichtung nach Anspruch 19, dadurch gekennzeichnet, dass die halbleitende Schicht (46) auf dem Entwickler-Haltekörper (41) aus einem Urethanharz ausgeführt ist, das eine Feuchtigkeitsabsorptionsrate von nicht mehr als 1% aufweist.
  21. Entwicklungsvorrichtung nach einem der Ansprüche 1 bis 20, dadurch gekennzeichnet, dass die Entwicklerschicht (45) in einem Dünnfilmzustand, der auf dem Entwickler-Haltekörper (41) gebildet ist, einen Widerstandswert von Rt [Ω] aufweist, wobei Rt > 5 × 107 erfüllt ist.
  22. Entwicklungsvorrichtung nach einem der Ansprüche 1 bis 21, dadurch gekennzeichnet, dass, unter der Annahme, dass eine Spannung, die an den Entwickler-Haltekörper (41) angelegt ist, Va [V] ist und eine Spannung, die an das Entwicklerschicht-Regelelement (43) angelegt ist, Vb [V] ist, Va - Vb ein Vorzeichen aufweist, das gegenüber einer Ladungspolarität des Entwicklers (10) umgekehrt ist.
  23. Entwicklungsvorrichtung nach einem der Ansprüche 1 bis 22, dadurch gekennzeichnet, dass, unter der Annahme, dass eine Spannung, die an den Entwickler-Haltekörper (41) angelegt ist, Va [V] ist und eine Spannung, die an das Entwicklerzuführungselement (42) angelegt ist, Vc [V] ist, Va - Vc ein Vorzeichen aufweist, das gegenüber einer Ladungspolarität des Entwicklers (10) umgekehrt ist.
EP19990111926 1998-06-22 1999-06-22 Entwicklungsvorrichtung Expired - Lifetime EP0967528B1 (de)

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JP17426098A JP2000010404A (ja) 1998-06-22 1998-06-22 現像装置
JP17426098 1998-06-22

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JP2006215243A (ja) * 2005-02-03 2006-08-17 Canon Inc トナーおよびフルカラー画像形成方法
JP2007333829A (ja) 2006-06-13 2007-12-27 Konica Minolta Business Technologies Inc トナー供給ローラ、現像装置および画像形成装置
JP2009150949A (ja) * 2007-11-29 2009-07-09 Ricoh Co Ltd 非磁性一成分現像装置、画像形成装置及び非磁性一成分現像方法
JP5377159B2 (ja) * 2008-08-29 2013-12-25 キヤノン株式会社 画像形成装置
JP4981842B2 (ja) * 2009-04-20 2012-07-25 株式会社沖データ 画像形成装置
CN101893836B (zh) * 2010-04-01 2011-11-16 珠海天威飞马打印耗材有限公司 处理盒

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JP2751210B2 (ja) * 1988-06-17 1998-05-18 ミノルタ株式会社 現像装置
JPH05188765A (ja) * 1992-01-16 1993-07-30 Toshiba Corp 現像装置
JP2987254B2 (ja) * 1992-05-29 1999-12-06 株式会社東芝 現像装置並びに画像形成装置
US5387967A (en) * 1993-09-23 1995-02-07 Xerox Corporation Single-component electrophotographic development system
JPH09311542A (ja) * 1996-05-22 1997-12-02 Konica Corp 現像装置及びそれを搭載したカラー画像形成装置
JP3749372B2 (ja) * 1998-02-26 2006-02-22 シャープ株式会社 一成分トナーの現像装置

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EP0967528A2 (de) 1999-12-29
CN1246663A (zh) 2000-03-08
JP2000010404A (ja) 2000-01-14
EP0967528A3 (de) 2001-01-31
DE69910907T2 (de) 2004-07-22
DE69910907D1 (de) 2003-10-09

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