Abstract: An image forming apparatus includes: an image carrier; a latent image forming device; a developing device; an electrode which faces to the image carrier; an electric power source, a toner contamination detecting device for detecting toner contamination onto the electrode; an electrode cleaning device for cleaning the electrode; and a controlling section, wherein the control section controls the electric power source to apply at least an alternating current voltage to the electrode so that toner image is rearranged by reciprocally moving toner of the toner image between the image carrier and the electrode control section and allows the electrode cleaning device to clean the electrode when the toner contamination detecting device detects toner contamination on the electrode, and performs the toner rearrangement by the electrode from which the toner contamination is removed.

Abstract: Disclosed is an image forming apparatus including a toner reallocation electrode to carry out a reallocation of a toner of a toner image, a toner detection section to detect a toner amount of the toner image and a control section to calculate a toner amount adhered to the toner reallocation electrode or a density distribution of the toner image based on the detected toner amount and to control an AC component of an applied voltage based on the calculated toner amount or density distribution, and the control section decides a maximum value of the AC component of the applied voltage based on the toner amount or decides a minimum value of the AC component of the applied voltage based on the density distribution, and the control section controls the AC component within a control range of smaller than or equal to the decided maximum value or greater than or equal to the decided minimum value.

Abstract: A developing apparatus, comprises an endless belt shaped donor member; a developer supporting member to carry developer including toner and magnetic carrier and to form a toner layer on the donor member; a first supporting member arranged in the inside of the donor member with a predetermined gap against the developer supporting member and to strain the donor member; a second supporting member arranged in the inside of the donor member with a predetermined gap against the developer supporting member and to strain the donor member; a toner supply bias applying section to apply onto the first supporting member a toner supply bias for supplying toner from the developer supporting member to the donor member; and a toner recovery bias applying section to apply onto the second supporting member a toner recovery bias for recovering toner from the donor member to the developer supporting member.

Abstract: An image forming apparatus includes: a supplying section for supplying developer; a first developing roller including plural magnetic poles and a first sleeve arranged rotatable to the first developing roller; a second developing roller including plural magnetic poles and a second sleeve arranged rotatable to the second developing roller, the second developing roller arranged adjacent to the first developing roller and parallel to the same; an electrode arranged between the first and second developing rollers; and a voltage applying unit for applying bias voltages each having different electric potential corresponding to the first developing roller, the second developing roller and the electrode, wherein an absolute value of the bias voltage to be applied to the electrode is larger than that of the bias voltage to be applied to the first developing roller and smaller than that of the bias voltage to be applied to the second developing roller.

Abstract: Described is a developing roller, which makes it possible to appropriately peel developer off the developing roller, even if the developing roller is a small-sized. The developing roller includes a non-magnetic developing sleeve and a magnetic member installed into an inner space of the developing sleeve and having plural magnetic poles including a peeling magnetic pole. When a reference position is defined as such a position that exhibits a maximum value of magnetic flux density to be generated in a normal direction by the peeling magnetic pole, a magnetic-flux density flat region within which the magnetic flux density is kept at substantially a constant value being closely approximate to the maximum value of the magnetic flux density and the reference position is included, exists while fulfilling an Equation indicated as follow: Z?7° where numeral Z indicates an angle of the developing roller in the magnetic-flux density flat region.

Abstract: An image forming apparatus includes: an image carrying body; a latent image forming unit to form an electrostatic latent image on the image carrying body; a developing unit to develop the electrostatic latent image on the image carrying body to form a toner image, the developing unit including a developing agent carrying body to carry a developing agent in a development region, and a direct-current power supply and an alternating-current power supply, both applying a developing bias voltage to the developing agent carrying body, the developing bias voltage generated by superimposing a direct-current voltage to an alternating voltage; a printing rate detecting unit to detect a printing rate; and a control unit to control the alternating-current power supply, wherein the control unit controls an output of the alternating-current power supply based on a detection result of the printing rate detecting unit.

Abstract: A developing apparatus, comprises an endless belt shaped donor member; a developer supporting member to carry developer including toner and magnetic carrier and to form a toner layer on the donor member; a first supporting member arranged in the inside of the donor member with a predetermined gap against the developer supporting member and to strain the donor member; a second supporting member arranged in the inside of the donor member with a predetermined gap against the developer supporting member and to strain the donor member; a toner supply bias applying section to apply onto the first supporting member a toner supply bias for supplying toner from the developer supporting member to the donor member; and a toner recovery bias applying section to apply onto the second supporting member a toner recovery bias for recovering toner from the donor member to the developer supporting member.

Abstract: There is described an image forming apparatus for forming a high-density image by using the reversal developing method and suppressing an occurrence of irregularities. The apparatus includes an image bearing member, a latent image forming device to form an electrostatic latent image, a magnetic field generating device to generate a magnetic field and a developing device to develop the electrostatic latent image so as to form a toner image on the image bearing member. At a developing region, the developer bearing member moves in a direction opposite to a moving direction of the image bearing member and the magnetic field generating device has a developing pole to form a magnetic brush for developing the electrostatic latent image. Further, an outer diameter R (mm) of the developer bearing member and a magnetic flux density Br1 (mT) of the developing pole fulfill the relationship of Br1?R×4.5.

Abstract: An image forming apparatus includes: a developing device which applies a developing bias voltage obtained by superimposing an AC bias voltage onto a DC bias voltage to a photoreceptor, and develops a latent image on the photoreceptor with a developer to form a toner image. The apparatus has a toner forced discharge mode for forming a toner image for forced discharge in a first image formation area provided in a non-image formation area other than a second image formation area on the photoreceptor to forcibly discharge a toner from the developing device. When the mode is selected, an AC bias voltage at a frequency lower than that in the second image formation area is applied to the first image formation area to develop a latent image for forced discharge, to form a toner image, and a toner of the toner image is collected by a cleaning device.

Abstract: Disclosed in an image forming apparatus in which an electrostatic potential and/or frequency of AC voltage of development bias is controlled according to information on recording material. The information is preferably glossiness information of the recording material.

Abstract: There is described an image forming apparatus, which prevents an occurrence of worm-shaped image irregularities even in the high-speed developing operation to form a high quality image. In the image forming apparatus, the contact developing employing a two components developer including toner and carrier is conducted in such a manner that the latent image bearing member and the developer bearing member move in directions being opposite relative to each other at a developing region where the latent image bearing member and the developer bearing member are opposed to each other. The frequency of the AC current component and a line velocity of the latent image bearing member fulfill a condition indicated as follow: vp/f?70condition 1 where vp (mm/sec) is the line velocity of the latent image bearing member and f (kHz) is the frequency of the AC current component.

Abstract: An image forming apparatus includes: an image carrying member; a latent image forming unit to form an electrostatic latent image on the image carrying member; a developing unit to develop the electrostatic latent image on the image carrying member to form a toner image; a forcible discharge unit to forcibly discharge the toner from the developing unit; a toner supplying unit to supply toner by the discharged quantity; and a fog-detection unit to detect fog of the image, wherein the forcible discharge unit forcibly discharges the toner from the developing unit based on a detected result of the fog-detection unit.

Abstract: A development apparatus has: a housing in which a developer supplying/collecting unit and a developer stirring unit are arranged with a circular passage for carrying developer; a developer carrying member placed at a front side of the developer supplying/collecting unit; a developer supplying/collecting section for carrying the developer; and two developer stirring sections arranged in the front-and-rear direction so as to face, wherein, a toner supplying opening is formed above a position where the two developer stirring sections face and at an upstream side in a developer carrying direction, the two developer stirring sections are rotated at the facing position to move peripheries in a forward direction, the developer carrying direction by the two developer stirring sections is substantially opposite to one by the developer supplying/collecting section, and developer carrying capability of the two developer stirring sections is set to be made equal to that of the developer supplying/collecting section.

Abstract: An image forming apparatus includes: a developing device which applies a developing bias voltage obtained by superimposing an AC bias voltage onto a DC bias voltage to a photoreceptor, and develops a latent image on the photoreceptor with a developer to form a toner image. The apparatus has a toner forced discharge mode for forming a toner image for forced discharge in a first image formation area provided in a non-image formation area other than a second image formation area on the photoreceptor to forcibly discharge a toner from the developing device. When the mode is selected, an AC bias voltage at a frequency lower than that in the second image formation area is applied to the first image formation area to develop a latent image for forced discharge, to form a toner image, and a toner of the toner image is collected by a cleaning device.

Abstract: An image forming apparatus includes: an image carrying member; a latent image forming unit to form an electrostatic latent image on the image carrying member; a developing unit to develop the electrostatic latent image on the image carrying member to form a toner image; a forcible discharge unit to forcibly discharge the toner from the developing unit; a toner supplying unit to supply toner by the discharged quantity; and a fog-detection unit to detect fog of the image, wherein the forcible discharge unit forcibly discharges the toner from the developing unit based on a detected result of the fog-detection unit.

Abstract: An image forming apparatus includes: an image carrying body; a latent image forming unit to form an electrostatic latent image on the image carrying body; a developing unit to develop the electrostatic latent image on the image carrying body to form a toner image, the developing unit including a developing agent carrying body to carry a developing agent in a development region, and a direct-current power supply and an alternating-current power supply, both applying a developing bias voltage to the developing agent carrying body, the developing bias voltage generated by superimposing a direct-current voltage to an alternating voltage; a printing rate detecting unit to detect a printing rate; and a control unit to control the alternating-current power supply, wherein the control unit controls an output of the alternating-current power supply based on a detection result of the printing rate detecting unit.

Abstract: There is described an image forming apparatus, which prevents an occurrence of worm-shaped image irregularities even in the high-speed developing operation to form a high quality image. In the image forming apparatus, the contact developing employing a two components developer including toner and carrier is conducted in such a manner that the latent image bearing member and the developer bearing member move in directions being opposite relative to each other at a developing region where the latent image bearing member and the developer bearing member are opposed to each other. The frequency of the AC current component and a line velocity of the latent image bearing member fulfill a condition indicated as follow: vp/f?70??condition 1 where vp (mm/sec) is the line velocity of the latent image bearing member and f (kHz) is the frequency of the AC current component.

Abstract: There is described an image forming apparatus for forming a high-density image by using the reversal developing method and suppressing an occurrence of irregularities. The apparatus includes an image bearing member, a latent image forming device to form an electrostatic latent image, a magnetic field generating device to generate a magnetic field and a developing device to develop the electrostatic latent image so as to form a toner image on the image bearing member. At a developing region, the developer bearing member moves in a direction opposite to a moving direction of the image bearing member and the magnetic field generating device has a developing pole to form a magnetic blush for developing the electrostatic latent image. Further, an outer diameter R (mm) of the developer bearing member and a magnetic flux density Br1 (mT) of the developing pole fulfill the relationship of Br1?R×4.5.

Abstract: Disclosed in an image forming apparatus in which an electrostatic potential and/or frequency of AC voltage of development bias is controlled according to information on recording material. The information is preferably glossiness information of the recording material.

Abstract: A developing device has a rotary developer carrier, a rotary developer supply and collection member, a first and second rotary developer stirring members for stirring the developer while conveying and circulating the developer between them in the direction opposite to each other and having the same developer conveyance power, and a third rotary developer stirring member having a zero conveyance power in the rotary axis direction, which are provided in a housing in parallel with each other in this order in the direction to leave a latent image carrier. A toner replenishment inlet is provided at an upper part where the second and third stirring members face each other, and on an upstream side of the second stirring member in the developer conveyance direction, and the second and third stirring members are rotated downwardly at the position where both developer stirring members face each other.