Abstract: An image forming apparatus such as an electrophotographic copier and an electrophotographic printer. The image forming apparatus includes: a photoreceptor for forming a toner image on its surface; a charger for charging the surface with a bias voltage, including a DC component and a AC component, through a magnetic brush member which is in contact with the surface; a driving unit for moving both of the surface of the photoreceptor and the magnetic brush member in synchronism; a laser unit for imagewisely exposing a predetermined image area of the surface, which is charged by the charger, so that a latent image is formed on the surface; and a discharge lamp for exposing the surface with light so that the surface is discharged.

Abstract: An imagewise exposure device exposes the inner surface of a rotating photoreceptor. A developer layer is provided around the surface of a first developing roller to which a DC voltage, the polarity of which is the same as that of charge given to the insulating toner of the developer, is applied. The developer layer on the first developing roller contacts the outer surface of the photoreceptor, corresponding to the inner surface exposed, so that a toner layer is formed on the outer surface of the photoreceptor. A toner image is formed when a developer layer provided around a second developing roller contacts the outer surface of the photoreceptor on which the toner layer is formed, wherein a DC voltage having polarity reverse to that of the first developing roller is applied to the second developing roller.

Abstract: An image forming machine such as a copier and a printer for forming a color image on a recording sheet. The image forming machine includes: a photoreceptor for carrying the color image; an image writer such as a laser beam generator for forming a latent image of the color image on a surface of the photoreceptor; plural color developers for developing the latent image with color toners so that a developed color image is formed on the surface of the photoreceptor; a transferer for transferring the developed color image from the photoreceptor to the recording sheet; a cleaner for cleaning a residual portion of the developed color image on the photoreceptor; and a controller for controlling a cleaning operation of the cleaner which starts the cleaning operation after the transferring operation is completed.

Abstract: An image forming apparatus includes a process cartridge that incorporates a photoreceptor and a plurality of developing devices. The process cartridge is provided with a first driving shaft to drive the photoreceptor and a second driving shaft to independently drive the developing devices. When the process cartridge is mounted in the image forming apparatus which includes spaced apart first and second gears, the first and second driving shafts are coupled separately with the spaced apart first and second gears so that driving forces are separately transmitted to the first and second driving shafts. A flywheel is mounted on a third driving shaft that is coupled with the first driving shaft to drive the photoreceptor. Since the developing devices are constructed to receive a large number of different possible loads, the developers are placed in a condition where vibrations are created easily by the driving of the various possible loads.

Abstract: A device for charging a photoreceptor on which a toner image is formed, comprises a rotatable sleeve, at least two magnets disposed in the sleeve so as to attract magnetic particles in a form of magnetic brush, and a electric power source to provide the photoreceptor with an electric charge through the magnetic brush. One of the magnets is disposed upstream of the closest point between the photoreceptor and the sleeve, and the other magnet is disposed downstream of the closest point.

Abstract: The invention provides a method of forming an image on an imaging surface of a photoreceptor having a light decay characteristic so that the potential of the imaging surface is slowly decayed in an initial period of exposure and the potential of the imaging surface is sharply decayed in a middle period of exposure. The imaging surface is charged to an electric potential, exposed with a light beam, wherein the light beam has the maximum light amount I.sub.0 in the light amount distribution thereof on the imaging surface so as to satisfy following condition:1.2.times.P.sub.178 .ltoreq.I.sub.0 .ltoreq.2.5.times.P.sub.1/2,in which P.sub.1/2 is a half decay exposure light amount for decaying the potential of the imaging surface from an initial potential value before the exposure to the half of the initial potential value.

Abstract: A rotating sleeve-type magnetic brush cleaning apparatus removes residual toner from a peripheral surface of an image carrying member of an image former. The apparatus comprise a magnetic brush that includes electrically insulated magnetic particles provided on an outer surface of the rotating sleeve which sweep the peripheral surface of the image carrying member; and a voltage source for applying a superposed electric potential including a DC voltage component and an AC voltage component between the image carrying member and the magnetic brush. The magnetic brush is biased to a potential which is reverse in polarity to an electrification polarity of the toner by the DC potential.

Abstract: A toner image forming method is disclosed. In the method a photoreceptor having a shorter circumferene than length of a toner image to be transferred is used. The photoreceptor is exposed with an exposing light according to an image information to form a latent image and is processed with a step of removing residual toner particles on a non-image portion on the photoreceptor and developing a latent image on the photoreceptor with toner particles at a same time or successively to form the toner image. The toner particles have a specral characteristics which allows tho exposing light to pass through the toner particles. The method allows to provide a compact copying apparatus.

Abstract: An image forming machine has a charging roller on which magnetic particles are supplied to form a magnetic brush and an image forming body which is charged under the condition that the magnetic brush on the charging roller is in an alternating electric field. When the distance between a regulating member that regulates an amount of the magnetic particles passing through and the charging roller is defined to be DB and the distance between the image forming body and the charging roller is defined to be DI, an inequality of 0.7 DB.ltoreq.DI.ltoreq.1.0 DB is satisfied. More preferably, DB is in the relation of 0.2.ltoreq.DB.ltoreq.1.0 in mm.

Abstract: An image processing apparatus for changing an image size wherein the document is marked with two kinds of color markers differing in color so as to be designated a pre-change region in which an image size is to be changed and a post-change region indicating a region after the image size has been changed. The apparatus comprises a condition detector to detect the pre-change region and the post-change region and obtains a magnification of the image size change on the basis of the pre-change region and the post-change region.

Abstract: In a color image forming machine including a belt-shaped photoreceptor stretched around a plurality of rollers, and a horizontal portion of the photoreceptor being disposed above and in parallel to face a plurality of developing devices, a charging device and a transfer device are disposed to face the photoreceptor at a common position where the photoreceptor is curved around one roller. A cleaning device is disposed to face the photoreceptor at a position where the photoreceptor is curved around the other roller. The charging device is used as a transfer device by changing supplied voltage or is interchangeable with the transfer device by being either slid or rotated between two positions. The photoreceptor, the developing devices and the cleaning device are integrally formed as a cartridge which is detachably mountable to the machine.

Abstract: An image forming machine such as a copier or a printer for developing a latent image on a photoreceptor with toner. The image forming machine includes a sleeve for charging the photoreceptor; magnetic particles for forming a magnetic brush on a surface of the sleeve; a driver for driving the sleeve so that the magnetic brush is moved; and a power applying circuit for applying an alternating current between 20 and 500 .mu.A/cm on to a charging area between the sleeve and the photoreceptor; in which the sleeve is located in the vicinity of the photoreceptor so that the magnetic brush is in contact with the surface of the photoreceptor.

Abstract: Apparatus for charging an imaging surface of a photoreceptor. The apparatus forms a magnetic brush on a cylinder spaced apart from and facing the photoreceptor by a magnet disposed in the cylinder. The cylinder and the magnet are rotatable relative to each other so that the magnetic brush moves around the cylinder and comes in contact with the imaging surface of the photoreceptor. An electric bias source is provided to apply an electric bias voltage having a DC voltage component and an AC voltage component between the imaging surface of the photoreceptor and the cylinder, whereby the imaging surface is charged by the magnetic brush under the electric bias voltage.

Abstract: An image forming apparatus has a plurality of mixed input thereto including one-sided and two-sided documents, and then copied on sheets which are successively outputted in accordance with the supplied documents. The apparatus has a feeder to feed the documents to a reading station, and a discriminator to discriminate whether each of the documents is a one-sided or a two-sided document. Then the apparatus selectively outputs copied sheets in either a one-sided copy mode, a two-sided copy mode or a mixed copy mode in which one-sided and two-sided copy sheets are outputted in accordance with the mixed one-sided and two-sided documents.

Abstract: The invention provides a photoreceptor belt for forming a latent image on its imaging surface. The photoreceptor belt is stretched in the form of a loop around a plurality of rollers so as to be rotated for carrying a formed image. Both ends of the photoreceptor belt are bonded in the manner that the leading end in relation to the rotation direction is positioned inside than the trailing end in relation to the form of loop and the inner surface of the trailing end is superimposed on the outer surface of the leading end. Cleaning device for cleaning the imaging surface of the photoreceptor belt is disposed to have a cleaning direction opposite to the rotation direction of the photoreceptor belt. The photoreceptor belt is positioned to stop where the bonded ends of the belt are proximate to the corona charging device.

Abstract: An image forming apparatus is provided with a rotatable upper cover, one surface of which serves as a first exit tray on which recording sheets are discharged with image sides face downward, the other surface of which serves as a second exit tray on which recording sheets are discharged with image sides face upward. Guide members which are activated in accordance with the rotation of the rotatable upper cover are provided above delivering rollers, thereby the recording sheets delivered by the delivering rollers are selectively discharged with the image sides either face downward to the first exit tray or face upward to the second exit tray.

Abstract: A color image forming apparatus for forming a color image. An image retainer is provided for carrying the color image, and a charger charges a surface of the image retainer. A latent image former forms a latent image on the charged surface of the image retainer, and a multicolor developer develops the latent image. A black developer develops the latent image. A transfer sheet conveyer conveys a transfer sheet and transfers the developed latent image onto the transfer sheet. A cleaner cleans a residual developer on the surface of the image retainer. The image retainer, either one of the black developer or the multicolor developer, and the cleaner are formed as a detachable processing cartridge, and the rest of the black developer or the multicolor developer is detachable to the body of the color image forming apparatus.

Abstract: An apparatus identifies the type of a document from color image signals either a color document, a black and white document or a marked document, the marked document having a image processing region designated with a color marker differing in color from possible colors of the document to be read, thereafter applies one of a plurality of processing modes to the color image signals in accordance with the type of the document.

Abstract: A color image forming machine such as a copier or a printer for producing a toner image, corresponding to an original image, on a recording sheet. The color image forming machine has a photoreceptor for forming the toner image on its surface; a transferrer for transferring the toner image from the photoreceptor to the recording sheet; and a fixer for fixing the toner image on the recording sheet. The fixer includes (1) an endless heat belt which is supported by a heat roller and a separation roller; and (2) an endless conveyance belt which is supported by a pressure roller and another separation roller; in which the endless heat belt and the endless conveyance belt are partially pressed together by the first pair which are inclined relative to one another, and the second pair so that a nip region is created between the first pair of rollers and the second pair of rollers. The endless heat belt and the endless conveyance belt have a glossy surface.

Abstract: An image forming apparatus in which a process cartridge, including an image carrying member and an operation member with respect to image forming, facing the image carrying member, is movably provided. An opening on the process cartridge in accordance with the operation member is covered by a shielding member in the main body of the apparatus when the process cartridge is moved from the apparatus in response to an opening movement of an external cover which provides access to the interior of the apparatus.