Abstract: A contact shock dampening and development nip forming apparatus for developers includes a unit to dampen a contact shock and to form a development nip installed on both ends of a developing roller to be disposed between a photosensitive body and the developing roller. Accordingly, the contact shock dampening and development nip forming apparatus absorbs shocks applied to the photosensitive body from the developing roller upon changing the developers, to thereby protect the photosensitive layer of the photosensitive body and extend the lifespan of the photosensitive body. The apparatus also maintains a thickness of the development nip to thereby obtain a steady image quality, even though the developing roller and/or the photosensitive body may be formed of solid substances.

Abstract: An image forming apparatus of this invention is composed of: an image carrier; a latent image forming unit to form a latent image on the image carrier, a developing device having a developing unit for supplying a developer to the latent image formed on the image carrier by sliding in the direction to contact/separate to/from the image carrier in a main body; a positioning device to maintain the developing device in the operable state for development of the image in the main body; and a driving device to connect/separate the developing device to/from the positioning device by applying load in the sliding direction to the developing device in the main body and after connecting the developing device to the positioning device, moving the developing device in the direction to leave from the image carrier. After connecting/separating the developing device to/from the positioning device, the load applied to the developing device by the driving device is cancelled.

Abstract: An apparatus for forming a color image using electrophotography includes a photosensitive drum on which a predetermined electrostatic latent image is formed, a plurality of developing units including a developing roller supplying toner to a surface of the photosensitive drum to develop the electrostatic latent image, and pressure cams sequentially or selectively pressing corresponding ones of the developing units toward the photosensitive drum when the electrostatic latent image is developed. A bracket slide disposed in the apparatus uses tension springs to generate the same normal force in a predetermined range regardless of relative positions of the developing units, and the same normal force are applied to the photosensitive drum from the respective developing rollers while reducing a shock occurring when the developing roller contacts the photosensitive drum. Jitter and bending of an image can be removed or minimized, and the deterioration of a image quality due to a pressure difference can be prevented.

Abstract: An image forming apparatus according to an embodiment of the present invention comprises a plurality of developing devices, a plurality of developing device assemblies, and a controller. At least one developing device is provided for each type of toners to form the multi-color images. Each developing device assembly carries a plurality developing devices. The controller switches the developing devices carried by one of the developing device assemblies, while the developing devices carried by another developing device assembly are operating.

Abstract: An image forming apparatus includes a rotatable photosensitive belt which carries an electrostatic latent image, a laser exposing device which forms the electrostatic latent image on the photosensitive belt, a plurality of developing devices which selectively supply developers of different colors to the electrostatic latent image by rotation of developing rollers and develop toner images of different colors, a driving device which rotates the developing rollers, a moving device which selectively moves the developing devices between a first position in which the developing rollers contact the photosensitive belt and a second position in which the developing rollers separate therefrom, and a transfer device which superimposes and transfers the toner images onto a medium. A control device rotates a developing roller at least one revolution in the second position before the developing device, which has the developing roller, moves to the first position and develops a latent image.

Abstract: A latent image is formed on a photoreceptor. Each of a plurality of toner carriers carries toner of a single color to be transferred onto the photoreceptor to make the latent image visible. Each of the toner carriers is fixed at a predetermined distance from a surface of the photoreceptor. A first bias supplier supplies a first bias required to transfer the toner to the photoreceptor to one of the toner carriers which is subjected to a developing operation. A second bias supplier supplies a second bias which is not enough to transfer the toner to the photoreceptor to the other toner carriers which are not subjected to the developing operation.

Abstract: The image forming apparatus includes a plurality of image forming portions, and a first switching device and a second switching device that act on a plurality of clutch device. The second switching device communicates with the first switching device and operates in association with an operation of the first switching device. This makes it possible to simplify the construction of the image forming apparatus and to suppress reduction of the service life of an image bearing member.

Abstract: An image forming apparatus of this invention is composed of: an image carrier; a latent image forming unit to form a latent image on the image carrier, a developing device having a developing unit for supplying a developer to the latent image formed on the image carrier by sliding in the direction to contact/separate to/from the image carrier in a main body; a positioning device to maintain the developing device in the operable state for development of the image in the main body; and a driving device to connect/separate the developing device to/from the positioning device by applying load in the sliding direction to the developing device in the main body and after connecting the developing device to the positioning device, moving the developing device in the direction to leave from the image carrier. After connecting/separating the developing device to/from the positioning device, the load applied to the developing device by the driving device is cancelled.

Abstract: A developing apparatus of an electrophotographic printer for developing an image on a photoreceptive drum includes a disc rotating independently of the photoreceptive drum at both sides of the photoreceptive drum and having at least one cam groove formed on an outer circumferential surface thereof. A developing unit includes a housing containing developer and a developing roller supported by both sidewalls of the housing and having a shaft contacting the outer circumferential surface of the disc. An elastic member is provided at a rear surface of the housing and presses the developing apparatus toward the photoreceptive drum. Thus, since the disc having at least one cam groove is provided on the outer circumferential surface and rotates independently of the photoreceptive drum, the developing roller can be detached from the photoreceptive drum at a predetermined pressure.

Abstract: A method for forming an image in an electrophotographic printer. The method includes the steps of rotating a developing roller at the same linear velocity as that of a photosensitive medium in a state where the developing roller is separated from the photosensitive medium, moving a developer so that the developing roller is in contact with the photosensitive medium, and changing the linear velocity of the developing roller to be faster than that of the photosensitive medium after contact and proceeding with the developing process, rotating the developing roller at the same linear velocity as that of the photosensitive medium after completing the developing process, and moving the developer so that the developing roller is separated from the photosensitive medium.

Abstract: A color electrophotographic apparatus eliminates necessity of mechanism for urging the developer from the front side. The developer is placed away from a photo conductor. On both sides of the developer, mutually cooperated gears are provided. One of the gear meshes with a drive gear with a clutch for driving the developer. The other gear is meshed with a brake gear coupled with a brake mechanism whose brake function can be turned On and OFF by an electric signal. The drive gear is arranged to urge the developer onto the photo conductor by rotation thereof. When the gear of the developer rotates, the brake gear is arranged at a position to urge the developer onto the photo conductor. The torque to start slippage of the brake is set at a value to be greater than a force of a spring pushing back the developer.

Abstract: An image forming apparatus including a plurality of process stations vertically arranged each of which includes an image bearing member on which a latent image is to be formed and a developing device for developing the latent image, image bearing member driving devices, for driving the image bearing members, development driving devices, for driving the developing devices, and a transfer material bearing and conveying device for bearing and conveying the transfer material, wherein, while the transfer member is vertically conveyed through transfer nips that are formed by the transfer material bearing and conveying device and the image bearing members of all of the plurality of process stations, images formed by the plurality of pocess stations are sequentially transferred to the transfer material to form an image, and wherein process stations to be used for image forming can be selected, and the image bearing member driving devices and the development driving devices are controlled, so that, during an image for

Abstract: An image forming apparatus includes a rotatable photosensitive belt which carries an electrostatic latent image, a laser exposing device which forms the electrostatic latent image on the photosensitive belt, a plurality of developing devices which selectively supply developers of different colors to the electrostatic latent image by rotation of developing rollers and develop toner images of different colors, a driving device which rotates the developing rollers, a moving device which selectively moves the developing devices between a first position in which the developing rollers contact the photosensitive belt and a second position in which the developing rollers separate therefrom, a transfer device which superimposes and transfers the toner images onto a medium, and a control device which rotates the developing rollers at least one revolution in the second position before one of the developing devices moves to the first position and develops a latent image.

Abstract: The developing device has four developing units arranged along a photosensitive belt stretched across endlessly. These developing units contain toners of different colors, and each has a developing roller at its leading end which faces the photosensitive belt. The developing device has a contact-enabling mechanism for selectively bringing one of the four developing units into contact with the photosensitive belt. The contact-enabling mechanism has four cams provided such an arrangement that they are out of phase with each other by an angle of 72 degrees, thereby brining each of the developing units into contact with the photosensitive belt, one driving source for rotating the four cams and one clutch for transmitting a driving force from the driving source to the four cams so as to rotate them at the same time.

Abstract: In an image forming apparatus that is capable of forming a color image by bringing plural one-component developing devices in contact with a photosensitive belt, a two-component developing device for black image forming is arranged to face the photosensitive belt in an area wherein the belt is not displaced. By controlling this two component developing device in either the ready to developing state or the non-developing state, when forming a color image, the one-component developing devices are brought in contact with or separated from the photosensitive belt and when forming a monochrome image, using the two-component developing device, a developing nip is formed for the developing gap between the developing device and the photosensitive belt by the developer layer, and a black toner image is formed on the photosensitive belt.

Abstract: In an image forming apparatus that has a photosensitive belt and developing rollers for developing images by bringing the photosensitive belt in contact with the developing rollers when developing images, supporting members are provided for supporting the photosensitive belt in the state it is oscillated according to the contacting force of the photosensitive belt with the developing rollers. Thus, a large pressure applied to the nip portion between the photosensitive belt and the developing rollers is prevented and further, the tensile force applied to the photosensitive belt is prevented from largely fluctuating when the developing rollers contact the photosensitive belt by intruding into it.

Abstract: An image formation apparatus has photo conductor drums, and upstream developing rollers and downstream developing rollers that are brought into contact with respective photo conductor drums based on a changeover. The developing rollers develop latent images into visual images. A time required to change over a developing unit from one developing unit to the other developing unit is set as follows. A changeover time T2 from the downstream developing rollers to the upstream developing rollers respectively is set shorter than a changeover time T1 from the upstream developing rollers to the downstream developing rollers.

Abstract: The developing device has four developing units arranged along a photosensitive belt stretched across endlessly. These developing units contain toners of different colors, and each has a developing roller at its leading end which faces the photosensitive belt. The developing device has a contact-enabling mechanism for selectively bringing one of the four developing units into contact with the photosensitive belt. The contact-enabling mechanism has four cams provided such an arrangement that they are out of phase with each other by an angle of 72 degrees, thereby brining each of the developing units into contact with the photosensitive belt, one driving source for rotating the four cams and one clutch for transmitting a driving force from the driving source to the four cams so as to rotate them at the same time.

Abstract: A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus, includes a first frame; a second frame coupled with the first frame for rotation about a shaft; an electrophotographic photosensitive drum provided in the first frame; a developing member, provided in the second frame, for developing an electrostatic latent image formed on the photosensitive drum with a developer; a developing member, provided in the second frame, for developing an electrostatic latent image formed on the photosensitive drum with a developer; an elastic member for applying an elastic force between the first frame and the second frame to urge the developing member to the photosensitive drum; a force receiving portion, provided downstream of the shaft with respect to a mounting direction in which the process cartridge is mounted to the main assembly of the image forming apparatus, for receiving a force from the main assembly of the image forming apparatus to keep the developing member

Abstract: An image forming apparatus has a plurality of shiftable developing devices that contain toner. The image forming apparatus includes a fixing apparatus for fixing a toner image onto a recording material by heat, and the plurality of developing devices are disposed above the fixing apparatus. When a predetermined time period has elapsed after a temperature of the fixing apparatus reaches a predetermined temperature, the plurality of developing devices are shifted away from the fixing apparatus. With this arrangement, the toner contained in the developing device is prevented from being softened, melted and solidified due to the heat from the fixing apparatus, thereby effecting image formation stably.

Abstract: An image forming apparatus including a plurality of process stations vertically arranged each of which includes an image bearing member on which a latent image is to be formed and a developing device for developing the latent image, image bearing member driving devices, for driving the image bearing members, development driving devices, for driving the developing devices, and a transfer material bearing and conveying device for bearing and conveying the transfer material, wherein, while the transfer member is vertically conveyed through transfer nips that are formed by the transfer material bearing and conveying device and the image bearing members of all of the plurality of process stations, images formed by the plurality of pocess stations are sequentially transferred to the transfer material to form an image, and wherein process stations to be used for image forming can be selected, and the image bearing member driving devices and the development driving devices are controlled, so that, during an image for

Abstract: An image forming apparatus is provided which can selectively drive a plurality of developing units by a simple structure accommodated in a small space. Two image stations are arranged along a direction of movement of an intermediate transfer belt. Each of the image stations is provided with a plurality of developing units arranged around a photosensitive drum. A developing unit driving system drives the plurality of developing units. A switching mechanism switches a transmission path of a power generated by the developing unit driving system so that the power is selectively transmitted to one of the developing units.

Abstract: An image forming apparatus includes a plurality of image forming units each including a single image carrier, a single writing device and a plurality of developing means each including a single developing roller for developing a latent image formed on the image carrier by the writing device with a developer to thereby produce a toner image. The image forming units are spaced by a preselected distance along the same surface of an intermediate image transfer belt to which the toner image is to be transferred from the image carrier. A selecting device causes the developing means to selectively perform development. A single bias power source applies a bias voltage for development to the developing means. A bias switching device applies the bias voltage output from the bias power source to one of the developing means selected by the selecting device according to the outputs of sensors respectively included in the image forming units.

Abstract: A method for operating electrographic printers or copiers uses toner particles of two different colors applied to a toner image carrier by at least two developing units. A force field is applied to at least one section of the travel path of the toner particles from a toner container to the toner image carrier to cause the toner particles to be carried in the direction of the toner image carrier. Changing the force field causes an interruption of the transfer of the toner particles with the developer stations are in a rest position.

Abstract: There is related to an image forming apparatus for forming a two-color toner image on a photosensitive body and transferring a batch of the image to a transfer material. The apparatus has a rotating and moving electrophotographic photosensitive body. Successively along a rotating direction of the photosensitive body arranged are a first developing device using a two-component developing agent constituted of a magnetic carrier and a nonmagnetic toner and a second developing device using a one-component magnetic developing agent different in color from the nonmagnetic toner. The apparatus also has a control circuit for stopping an image forming operation when a trouble occurs in an apparatus body.

Abstract: A process cartridge detachably mountable to a main assembly of an electrophotographic image forming apparatus includes an electrophotographic photosensitive member; and developing member for developing a latent image formed on the photosensitive member; The developing member is disposed at a position deviated from a developing position corresponding to a displacement of the developing member resulting from the driving force received from the main assembly of the apparatus when the process cartridge is in the main assembly.

Abstract: A color electrophotographic apparatus includes a photosensitive belt arranged obliquely, and a plurality of developing machines arranged on one side of the photosensitive belt in a stacked manner so as to be displaced from one another in a horizontal direction. The photosensitive belt is movable from below to above in a direction opposite to a direction of gravity when in a developing position. The developing machines include a non-magnetic, one component contact developing system having a developing roll for adhering toner on the photosensitive belt and a blade disposed below the developing roll for controlling an amount of toner adhering to the developing roll.

Abstract: An image forming apparatus including a rotatable developing member having a plurality of developing devices for developing an image bearing member at a first developing station, and a second single developing device arranged upstream of the rotatable developing member for developing the image bearing member exclusively at a second developing station different from the first developing station. The second developing device has a cover portion covering the rotatable developing member, and a portion of the cover portion is disposed at a position spaced apart from a rotation axis of the rotatable developing member by a predetermined length in a horizontal direction away from the image bearing member. The rotatable developing member rotates in an opposite direction with respect to the direction of rotation of the image bearing member to prevent toner from scattering toward the optical system.

Abstract: An image forming apparatus includes an image bearing member for bearing an electrostatic latent image; a first developing device for developing the electrostatic latent image on the image bearing member; a second developing device, faced to the image bearing member and having a movable developer carrying member for carrying toner and carrier, for effecting development after a first developed image provided by the first developing device passes through a position where the developer carrying member is faced to the image bearing member; and a preventing device for forming an alternating electric field between the developer carrying member and the image bearing member, while the second developing device is at reset to prevent the carrier of the second developing device from rubbing the first developed image.

Abstract: A developing unit of a multi-color image forming device and a controlling method thereof employ a rotatable turret and a plurality of developers, each having a developing roller. The developer contacts a photosensitive drum only when a toner image is formed on the photosensitive drum by moving the developer radially to the rotary center of the turret using a developer transporting unit, such as a cylinder.

Abstract: A color image forming apparatus provides the prolonged life of the photosensitive drums, carrier belt, and toner of the respective colors and improves the quality of the printed color image. A carrier belt transports a recording medium placed thereon so that the recording medium passes through a plurality of printing mechanisms which print images of different colors on the recording medium in superposition. Each printing mechanism prints an image of a corresponding color. The printing mechanism is adapted to be moved into its operative position where the photosensitive drum of the printing mechanism is in contact with the carrier belt to print the image on the recording medium, and into its non-operative position where the photosensitive drum of the printing mechanism is not in contact with the carrier belt.

Abstract: The printer comprises:a digital printing station (12);a support (20) for a roll (22) of the substrate web (24) carrying a plurality of synchronisation marks;means (28) for continuously feeding the substrate web (24) from the roll (22) past the printing station (12);a sensing device (32) positioned upstream of the printing station (12) for sensing the synchronisation marks on the web (24); andcontrol means (38) for initiating a printing sequence at the printing station (12) in response to the sensing of each of the synchronisation marks (26, 34, 36). Thereby a plurality of images are printed on the web (24), each at a predetermined location in the transport direction relative to an associated one of the synchronisation marks (26, 34, 36).

Abstract: A color printer which performs a printing operation according to data from an upper unit such as a host computer. Switching mechanisms each which switches the state of each color printing unit to either a return state or an evacuation state are respectively arranged to the color printing units. A control unit judges as an unused color a color satisfying a predetermined unused condition among the plural colors and controls the corresponding at least one of switching mechanisms to switch the state of the color printing units corresponding to the unused color to the evacuation state. Since the evacuation operation of the color printing unit is performed without deteriorating the printing performance, the reduced power consumption, prolonged serviceable life of a color printing unit with a low use frequency, and improved print quality can be realized.

Abstract: An image forming apparatus includes an image bearing member on which first and second electrostatic images are formed, a first developing device for developing the first electrostatic image on the image bearing member with a first toner, and a second developing device for developing the second electrostatic image on the image bearing member bearing the first toner image thereon with a second toner. The second developing device has a toner carrying member opposed to the image bearing member and carrying the toners thereon. The force with which the first toner, having mixed into the second developing device, is carried on the toner carrying member is smaller than the force with which the second toner is carried on the toner carrying member.

Abstract: A color electrophotographic printing system that uses one switched developer power supply for all developers and that enables a reduced size by reducing the interdocument zone. The interdocument zone is reduced by using a developer order in which the last used developers in a development cycle is physically located first. Beneficially, the developer that is used first is physically located last.

Abstract: A revolution control for a sun and planetary gear system including supporting members for the planetary gears which are revolvable around the same gear and a cam mechanism engaging a portion of the supporting member. The cam mechanism includes a cam shaft carrying a plurality of cams and there is a driving gear engaging the cam shaft. Also, two transmission gear trains present permit the driving gears to operate in either direction while still driving the toner replenishers in the same direction.

Abstract: A developer in use with an image forming apparatus. The developer includes: a developing sleeve which rotates and holds toner on itself so as to develop a latent image on a photoreceptor with the toner; a driving motor for generating a rotational driving force; a drive transmission for transmitting the rotational driving force of the driving motor to the developing cartridge in which the drive transmission has a transmitting state and an untransmitting state; and a shock easing controller or member for easing a shock of transmission of the rotational driving force to the developing sleeve in the transmitting state, in which the shock easing controller or member is provided in at least one of the driving means and the drive transmission means.

Abstract: A heat and pressure roll fuser is disclosed for fixing powder images to various substrates. Each of the rolls has a deformable outer layer. One of the rollers is crowned such that its center has a larger diameter than its ends. The other roller has a uniform diameter along its entire length. The difference in the center diameter and the end diameters is such that the fuser produces a nonuniform nip and a uniform nip velocity.

Abstract: A color toner having color toner particles containing a coloring agent and a non-linear polyester resin synthesized from a compound represented by the following general formula (1) or an acid anhydride thereof; ##STR1## wherein n is an integer of at least 3, R is a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, an alkenyl group having 2 to 18 carbon atoms, or an aryl group having 6 to 18 carbon atoms, the pigment particles in the color toner particles have a number average diameter of no greater than 0.7 .mu.m and contain at least 60 percent by number of the pigment particles having a diameter of 0.1 to 0.5 .mu.m and no greater than 10 percent by number of the pigment particles having a diameter of at least 0.8 .mu.m, and the color toner has a softening temperature of 85.degree. C. to 120.degree. C. calculated from a flow tester curve.

Abstract: In an image printer performing multi-color printing, two magnetic poles having the same polarity are provided adjacent to each other in a position facing the printing body of the second developing agent holding body provided in the second developing unit, and development is performed under a condition satisfying the following formulas;B1.ltoreq.1100,1000.ltoreq.B2.ltoreq.1200,-300.ltoreq.B1-B2.ltoreq.0,F.apprxeq.0where B1 (gauss) is a magnetic flux density on the surface of the developing agent holding body of one magnetic pole of the magnetic poles arranged in the downstream side of the transmitting direction of the developing agent, and B2 (gauss) is a magnetic flux density on the surface of the developing agent holding body of the other magnetic pole of the magnetic poles arranged in the upstream side of the transmitting direction of the developing agent, and F (gf) is a rubbing force to the printing body of the magnetic brush in the second developing unit.

Abstract: Images are formed using first and second fluidized beds of non-magnetic toner having first and second, respective, single applicator rollers. A charge retentive surface such as a photoconductive belt is uniformly charged (e.g. by a corona device) to a predetermined voltage level, and at least first and second different, spaced, latent electrostatic images are formed on the surface at different locations (such as by a laser based output scanning device). The surface is then moved past the first applicator roller, and then the second applicator roller.

Abstract: In order to accomplish the present invention, there is provided a voltage supply system for use in a color electrophotographic printer where the electrophotographic printer has more than one developer. A high voltage AC source receives a select signal that indicates which one of the developers is presently in use. Provided one and only one developer is in use, the alternating current source outputs an AC voltage. A switching network is connected to the HVAC current source and also each developers. The switching network also receives the select signal and routes the AC voltage to the active developer. Stress to the switching elements in the switching network is reduce by proper sequencing of the application and removal of the HVAC and network reconfigurations.

Abstract: For image reproduction, a submodular unit including a developing roller and a doctor blade is adjustably mounted on a modular developing unit of a rotary developing apparatus. In general, the modular developing unit is rotatably positioned to juxtapose a photoreceptor drum. This juxtaposed position defines the developing position. The toner loaded on the developing roller in the developing position travels over a spacial gap between the developing roller surface and the photoreceptor drum surface. This crucial gap is necessary for successful image reproduction. However, this gap usually cannot be optimally maintained over extended time. The gap is also changed due vibration caused during shipment. In adjusting the gap, the submodular unit allows an independent and fine adjustment for each modular image developing unit. The submodular unit also allows an efficient assembly of the modular rotary developing unit.