Abstract: A toner including a resin and a colorant which is dispersed in the toner and which has an average major particle diameter not greater than about 0.5 &mgr;m, wherein the following relationships are satisfied: Ta≦100 (° C.), and (Tb−Ta)≧7.0 (° C.), wherein Ta represents a temperature at which the toner has a melt viscosity of 50,000 Pa·sec and Tb represents a temperature at which the toner has a melt viscosity of 5,000 Pa·sec.

Abstract: It is an exemplified object of the present invention to provide an image-forming device that can form a high-quality multicolor image at relatively low cost. To achieve the above object, the inventive image-forming device includes an endless belt that conveys a recordable medium; plural image-forming units that form a toner layer on the recordable medium via the endless belt; and a fixer that fixes the toner layer on the recordable medium, and a first pressing force applicable to the recordable medium by a last image-forming unit at a downstream side along a direction in which the recordable medium is conveyed among the plural image-forming units is greater than a second pressing force applicable to the recordable medium by another image-forming unit adjacent to the last image-forming unit at the downstream side among the plural image-forming units.

Abstract: This invention relates to color printing, and more particularly, to color laser printing systems. Such structures of this type, generally, employ a rotatable, carousel type shuttle color printer with a plurality of toner reservoirs such that one of the plurality of toner reservoirs is a high capacity toner reservoir.

Abstract: Toner image forming means for forming toner images having chromatic colors of Y, M and C, respectively, are disposed on one side of an intermediate transfer belt, while disposing toner image forming means for forming a black toner image on the other side of the intermediate transfer belt, alone and on a most downstream side of all the toner image forming means. Further, when a toner image on the intermediate transfer belt includes toner having a reverse polarity, a transfer or developing process is controlled to reduce electrostatic attraction force acting on an image carrier, thus providing a color image forming device having a main body reduced in size and capable of faster image formation of a monochromatic image which is more frequently used, and of efficiently forming a color image by suppressing a back-transfer phenomenon and improving color reproducibility.

Abstract: The system speed of the image forming apparatus is controlled to operate in one of two modes. In one embodiment, a controller coordinates the operation of a plurality of image forming units and the transporter. The controller sets a system speed of the image forming apparatus at a first speed when a first mode is set to form a color image using the plurality of image forming units and sets the system speed of the image forming apparatus at a second speed which is faster than the first speed when a second mode is set to form a single-color image using only an image forming unit provided at a most downstream position in a transportation direction of the transporter.

Abstract: An image forming apparatus suppresses several kinds of inconveniences caused by unnecessary contact of a belt-formed member with opposing members and drives the belt-formed member accurately even when the belt-formed member separated from a part of a plurality of opposing members. In an image forming apparatus having a belt-formed member supported by a plurality of supporting rollers and a plurality of opposing members located side by side in a line to oppose and contact the belt-formed member, a pivot mechanism is employed to temporarily separate the belt-formed member from a part of the opposing members for color image formation. The image forming apparatus also includes a tension roller dive mechanism to increase a relative distance between the tension roller and other supporting rollers to suppress a decrease in a tension of the belt-formed member during the above-described separation of the belt-formed member from the plurality of opposing members.

Abstract: An image forming machine comprising image bearing means, charging means, exposure means, reversal development means, transfer means, and cleaning means. The transfer means includes a rotationally driven transfer belt, and transfer voltage applicator means for applying a transfer voltage to the back side of the transfer belt. The transfer voltage applicator means applies the transfer voltage to the transfer belt over a predetermined effective transfer width. The face side of the transfer belt is brought into contact with the image bearing means via an image receiving member and directly over a predetermined effective contact width. The effective contact width is larger than an effective charging width and larger than the effective transfer width.

Abstract: Disclosed a tandem type color image forming apparatus and a color image forming method to reduce the cost of production without lowering the transfer efficiency. An electric potential setting member (170) is disposed in the tandem color image forming apparatus. The electric potential setting member (170) sets the electric potential difference between the front and back faces of a dielectric belt (160) in tandem image forming units (110 to 140) to approximately 0V before a transfer material (100) is adsorbed. This enables the electric potential difference between the front and back faces of the dielectric belt (160) in the respective color transfer positions to be set to approximately 0V. Therefore, there is a wide range of selecting the dielectric belt types, and the lowering of the transfer efficiency can be prevented, which is caused by the lowering of the resistance value of the dielectric belt surface after running.

Abstract: Disclosed is a color image forming apparatus in which a color image is formed by accumulating a visible image on an image transfer medium. The color image forming apparatus includes a plurality of forming means for forming the visible image on an image forming medium with a toner; and a plurality of transferring means for transfer the visible image onto the image transfer medium while bringing the visible image into contact with the image transfer medium.

Abstract: Disclosed here is a color-image forming apparatus that minimizes damage caused by friction between a photosensitive drum and an inter-stage transfer belt. The apparatus includes a plurality of image-forming units, each of which has the photosensitive drum carrying an electrostatic latent image thereon, a developing unit forming a toner image by applying toner to the latent image. Having separately different color toner therein, each image-forming unit is organized into a tandem layout. The inter-stage transfer belt is looped over plural rollers on its way of the endless path. While traveling the path along in the direction that the image-forming units are arranged, the belt forms a full-color toner image thereon by transferring plural toner-images on the drums one upon another. The belt is controlled to come into contact with the drums only while accepting the toner image from the drums.

Abstract: It is an exemplified object of the present invention to provide an image-forming device that can form a high-quality multicolor image at relatively low cost. To achieve the above object, the inventive image-forming device comprises an endless belt that conveys a recordable medium; plural image-forming units that form a toner layer on the recordable medium via the endless belt; and a fixer that fixes the toner layer on the recordable medium, and a first pressing force applicable to the recordable medium by a last image-forming unit at a downstream side along a direction in which the recordable medium is conveyed among the plural image-forming units is greater than a second pressing force applicable to the recordable medium by another image-forming unit adjacent to the last image-forming unit at the downstream side among the plural image-forming units.

Abstract: A color image forming apparatus of the present invention comprises: an intermediate transfer member being driven to rotate by a driving roller; a plural image forming units for forming superposed toner images on the intermediate transfer member, the plural image forming units being located below the intermediate transfer belt; a transfer member for transferring the superposed toner images formed on the intermediate transfer member onto a sheet of paper in a transfer area; and a pair of rotatable conveyance rollers for conveying the paper to the transfer area in synchronization with the superposed toner images on the intermediate transfer member, wherein a first distance from a image forming position, for the image forming unit located most-downstream in the plural image forming units relative to the movement of the intermediate transfer member, to the transfer area is longer than a second distance from a nipping area formed by the pair of conveyance rollers to the transfer area.

Abstract: A rotation member driving device and an image forming apparatus using the same are provided. Without enlarging the device and increasing the cost, by reducing a speed variation generated during one rotation of a rotation member such as an image holding member or an intermediate transfer member, the distortion or color misregistration of an image formed on or transferred onto the rotation member is reduced and a high quality image can be formed. In the rotation member driving device for rotating and driving the rotation member for image formation by a gear attached thereto, a relation between a phase of eccentricity of the rotation member and a phase of a cumulative pitch error in a rotation direction of the gear is set so that a variation of a surface speed due to the eccentricity of the rotation member is restrained from appearing on the image.

Abstract: An image forming apparatus of a tandem method includes a conveying member configured to provide to a recording member a conveying force in a sub-scanning direction, a plurality of image carriers configured to contact the conveying member with an equal interval between contacting portions of the plurality of image carriers and the conveying member, a contact force adjusting mechanism configured to freely adjust a contact force of the conveying member to the plurality of image carriers between a predetermined contact force and a decreased contact force, a plurality of toner image forming devices configured to form toner images of a predetermined pattern on the plurality of image carriers respectively. A length of the pattern in the sub-scanning direction is set shorter than a length of the equal interval.

Abstract: Utilizing an action of a transfer roller transferring a toner image formed on an intermediate transfer belt onto a sheet of paper can provide the belt with tension, and allows the belt and an urging roller to nip the sheet of paper. Thanks to this structure, a compact and inexpensive color image forming apparatus is obtainable.

Abstract: An image forming machine comprising image bearing means, charging means, exposure means, reversal development means, transfer means, and cleaning means. The transfer means includes a rotationally driven transfer belt, and transfer voltage applicator means for applying a transfer voltage to the back side of the transfer belt. The transfer voltage applicator means applies the transfer voltage to the transfer belt over a predetermined effective transfer width. The face side of the transfer belt is brought into contact with the image bearing means via an image receiving member and directly over a predetermined effective contact width. The effective contact width is larger than an effective charging width and larger than the effective transfer width.

Abstract: A color image forming apparatus in accordance with the present invention comprises: an intermediate transfer member having a movable surface; a plural image forming units for forming toner images on the intermediate transfer member at each of image-forming positions; and a transfer roller for transferring the toner images formed on the intermediate transfer member onto a sheet, the transfer roller having a circumferential length equal to the distance between adjacent image forming positions.

Abstract: A color image forming apparatus of the present invention comprises an intermediate transfer member having a movable surface, a plural image forming units for forming superposed toner images on the intermediate transfer member at a predetermined image forming pitch, and a transfer member for transferring the superposed toner images formed on the intermediate transfer member onto a sheet of paper, wherein the peripheral length of the intermediate transfer member is a non-integral multiple of the image forming pitch.

Abstract: A tandem type color image forming device having a plurality of process cartridges each being detachable from a frame. An intermediate image transfer belt extends vertically, and the process cartridges are arrayed in the vertical direction and supported by the frame. Each process cartridge installs therein a developing unit and a photosensitive drum, and each photosensitive drum is in confrontation with the belt- A front cover is provided in front of the process cartridges. If viewing from the front, when the front cover is opened, the process cartridges are accessible without any interference with ambient components, and the belt is positioned behind the process cartridges.

Abstract: An image forming apparatus includes a belt member to convey a sheet-formed medium, a belt supporting device to support the belt member, and a plurality of recording units including rotating image bearing members arranged in a conveying direction of the sheet-formed medium by the belt. The image forming apparatus performs processes of (1) forming a latent image on a surface of each image bearing member, (2) developing each latent image into a toner image with toner, and (3) then transferring each toner image onto the sheet-formed medium carried on the belt. A detection device detects arbitrary toner image patterns formed at the plurality of recording units and then directly transferred onto the belt, for obtaining information about density and placements of images without the toner patterns being deteriorated by contacting following downstream recording units.

Abstract: A toner for two-component developer characterized in that the surface area (A) of the toner mother particles containing linear polyester resin and coloring agents and the total projection area (B) of the external additives in diameter less than 50 nm that are added to the surface of the toner mother particles are as follows: 75%≦B/A≦150%

Abstract: A printer of the present invention includes a chain-delivery type of sheet conveying device arranged in an image transfer region that adjoins image transfer drums. The sheet conveying device includes a pair of drive pulleys, a pair of driven pulleys, a pair of chains each being passed over one drive pulley and one driven pulley, and a clamper affixed to the chains at opposite ends thereof. Each chain has a circumferential length that is an integral multiple of the circumference of an image transfer drum, and a number of teeth that is an integral multiple of the number of teeth of the drive pulley. A stabilizing mechanism is positioned in the image transfer region for preventing the chains from shaking.

Abstract: An image forming apparatus comprising an intermediate transfer belt 12 having a horizontal belt part 12a, and a transfer section 34 arranged opposite the horizontal belt part 12a of the intermediate transfer belt 12 for transferring to a sheet overlaid images formed on the intermediate transfer belt 12 by a plurality of image forming sections 20Y, 20M, 20C, 20K for overlaying multiple images of respectively different color, wherein a belt unit 110 comprises a frame 112, at least three rollers 14, 16, 18 supported on frame 112, and the intermediate transfer belt 12 supported on the exterior surface of these rollers, and wherein the belt unit 110 can be installed and removed from the image forming apparatus body perpendicular to the shafts of the rollers 14, 16, 18, and parallel to the horizontal belt part 12a.

Abstract: An image forming apparatus of the type in which it is possible to select an image forming station for image formation from a plurality of image forming stations, includes: a plurality of image forming stations each having an image bearing member for bearing a latent image and a developing device for developing the latent image on the image bearing member by a developer; transfer members adapted to come into contact with a medium member to induce a charge and to electrostatically transfer developed images formed in the plurality of image forming stations to the medium member; and a current control portion for controlling an electric current flowing through the transfer members, wherein the current control portion effects control such that no electric current flows through the transfer member corresponding to an image forming station not being used for image formation.

Abstract: An image forming apparatus including a plurality of image bearing members, a plurality of image forming portions for forming images on the plurality of image bearing members, a plurality of primary transfer portions for transferring the images on the plurality of image bearing members onto an intermediate transfer member, secondary transfer portions for transferring the image on the intermediate transfer member onto a transfer material, and a controller for controlling the primary transfer portion to operate until an image area on the image bearing member on which an image is being formed at the point when an image formation stop instruction is issued passes a transfer region in the primary transfer portion opposing to the image bearing member.

Abstract: An inage forming apparatus includes an image bearing member for bearing an image; a movable recording material carrying member for electrostatically carrying the recording material; transfer means for electrostatically transferring the image from the image bearing member onto the recording material carried on the recording material carrying member at a transfer position, the transfer means being located at a position across from a side of the recording material carrying member carrying the recording material; and control means for controlling timing of start of change of a current flowing through the transfer means in accordance with a kind of the recording material so that the current reaches a level effective to transfer the image from the image bearing member onto the recording material carried on the recording material carrying member within a period in which a non-image formation area of the recording material at its leading edge is passing the transfer position.

Abstract: An image forming apparatus suppresses several kinds of inconveniences caused by unnecessary contact of a belt-formed member with opposing members and drives the belt-formed member accurately even when the belt-formed member separated from a part of a plurality of opposing members. In an image forming apparatus having a belt-formed member supported by a plurality of supporting rollers and a plurality of opposing members located side by side in a line to oppose and contact the belt-formed member, a pivot mechanism is employed to temporarily separate the belt-formed member from a part of the opposing members for color image formation. The image forming apparatus also includes a tension roller dive mechanism to increase a relative distance between the tension roller and other supporting rollers to suppress a decrease in a tension of the belt-formed member during the above-described separation of the belt-formed member from the plurality of opposing members.

Abstract: The value of an AC voltage ingredient applied to charging rollers in the mono-colored black image forming mode is reduced to be smaller than the value applied in the full-colored image forming mode. Accordingly, in the mono-colored black image forming mode, the electric discharge between the charging rollers and photosensitive drums which do not form images is reduced, so that a shaving-off phenomenon on the surfaces of the photosensitive drums can be decreased, and thereby increasing a lifespan of the photosensitive drums.

Abstract: In a toner image forming apparatus, a contact member for pressing a work piece at a pressing position against a toner image on a movable transfer member so that the toner image is transferred from the transfer member onto the work piece is pressed against the transfer member while a test pattern toner image which is prevented from being transferred onto the work piece moves from a transfer position at which the toner image and the test pattern toner image are transferred onto the transfer member and a detecting position at which the test pattern toner image is detected to obtain a difference between the test pattern toner image on the transfer member and a desired test pattern image.

Abstract: An image forming apparatus comprising the following. That is, four photosensitive drums provided in a line along the transport path of a recording sheet, four transfer rollers respectively provided in positions opposite to the photosensitive drums, via the transport path. Here, when voltages are applied to the transfer rollers, each of them generates an electric field for transferring a toner image formed on the surface of the corresponding photosensitive drum onto the recording sheet. A constant voltage power supply, and a voltage distributing circuit by which an outputted voltage as it is from the constant voltage power supply is applied to one of the transfer rollers, while different voltages are applied to the remaining three transfer rollers by dividing the outputted voltage by means of three zener diodes.

Abstract: A color image forming apparatus includes a photosensitive belt, which consists of a resinous base sheet and an organic photosensitive layer formed thereon. The photosensitive layer consists of a charge transport layer and charge generation particles dispersed therein. The image forming apparatus ensures good color image quality even if the developer used for this former is toner made of styrene-acrylic resin. The image forming apparatus also includes developing rollers in contact with the photosensitive belt. Suitable shearing force can be applied to the toner if the speed ratio of the developing rollers to the photosensitive belt ranges from 1.3 to 2.0. The developer includes an external additive which has a particle diameter of 30 or more nm. The external additive can effectively prevent printed sheets from halation.

Abstract: After an image forming operation is finished, a motor that drives a belt is stopped after a predetermined time period passes since a sensor detects the only one mark provided on the belt. The predetermined time period is different for first, second and third job. This is repeated for the jobs thereafter. One job is a series of processing from the start of the motor to the stop of the motor. Thus, the belt stops at three different position for each consecutive three jobs.

Abstract: The present invention provides an image forming apparatus that has a plurality of image bearing members for bearing developer images thereon, and a plurality of developer containing portions for containing developers therein and provided correspondingly to respective ones of the plurality of image bearing members, wherein the developer images can be transferred from the plurality of image bearing members to a transferring member moving along the respective transferring positions of the plurality of image bearing members, and of the plurality of developer containing portions, a developer containing portion having greatest developer containing quantity is provided at least one of upstream of the most upstream one of the plurality of image bearing members and downstream of the most downstream one of the plurality of image bearing members, with respect to a moving direction of the transferring member.

Abstract: The present invention includes:

Abstract: An image forming apparatus is able to prevent the service life of an image bearing member thereof from expiring sooner than expected, without requiring an increase in size, complication, or increased cost of the apparatus. In an image forming apparatus adapted to form images by employing a plurality of image bearing members, when a monocolor mode wherein only a black toner is used to produce a monochrome image is selected, no toner image is formed on photosensitive drums of the colors other than the photosensitive drum on which a black toner image is formed. However, the photosensitive drums of the remaining colors continue to run while maintaining a speed difference in a four-full-color mode in relation to an intermediary transfer belt. This means that the photosensitive drums of the remaining colors wastefully slide against cleaning blades and the intermediary transfer belt, leading to wear or scratches.

Abstract: A detection hole is formed in a belt. When the detection hole arrives at the reference/edge sensor, the light from the reference signal detection light emitting element passes through the detection hole, and then arrives at the reference signal detection light receiving element. The controller operates so that data is transmitted to the laser scanner units at the wiring timing of each data based on the reference signal. Furthermore, the reference/edge sensor has another pair of light emitting and receiving elements, i.e., an edge signal detection light emitting element and an edge signal detection light receiving element. The belt is so attached that its end portion can always remain within a detectable area. In addition, corresponding to an area in which the belt shields a detectable range, it is possible to obtain an edge signal changing in analogue manner. In accordance with a change of the edge signal, the controller can thus control a steering roller.

Abstract: A color image forming device capable of preventing image from being degraded due to image transfer operations. A plurality of photosensitive drums are positioned in alignment in a rotational direction of intermediate recording medium. A plurality of developing rollers are provided in confrontation with corresponding photosensitive drums. Layer thickness regulating blades are provided in contact with corresponding developing rollers so as to form a thin toner layer having a two-layer thickness on the developing rollers.

Abstract: An electrophotographic color printer includes a photoconductor and a printing unit for producing a toner image on the photoconductor. The printing unit is removably provided in a receptacle in the printer.

Abstract: A system and method for controlling the imaging device in a single pass multi color electrophotographic printing machine, includes a photoconductive member defining a timing aperture, the member moving along a path in a printing machine and a plurality of imaging devices, each one of the plurality of imaging devices writing a latent image on the photoconductive member. The system further includes a sensor, located adjacent the photoconductive member, to sense the aperture in the photoconductive member as it passes the sensor and generate a signal indicative thereof and a control device, which generates a timing signal for each of the plurality of imaging devices as a function of the signal generated by the sensor and a plurality of predetermined parameters.

Abstract: A color image forming apparatus having a plurality of image forming units, a first attraction unit and a second attraction unit for attracting a recording sheet to a transport belt, and a controller for operating the first attraction unit when a first mode is set for forming a color image using all of the plurality of image forming units, and for operating the second attraction unit when a second mode is set for forming a single-color image using only one of the image forming units. In another embodiment, a controller sets a transfer pressure at a first pressure for each of the plurality of image forming units when the first mode is set and at a second pressure, which is higher than the first pressure, for the image forming units not being used to form the single-color image when the second mode is set.

Abstract: In an image forming apparatus according to the present invention, the toner images of the plural colors on the intermediate transfer member are electrostatically transferred to a transfer material, and the image forming charges the toner image of a color, among the toner images of the plural colors formed on the intermediate transfer member, different from the last color in such a manner that the charge amount per unit weight of the toner image of the different color becomes 0.5 to 1.5 times of the charge amount per unit weight of the toner image of the last color, after the formation of the toner image of the last color on the intermediate transfer member and prior to the transfer of the toner images of the plural colors on the intermediate transfer member to the transfer material.

Abstract: An image forming apparatus has a photosensitive drum on which toner images of different colors are formed and sequentially transferred in layers to an intermediate transfer drum. In the continuous color image formation, depending on whether to be the first page or after second page, for example, the control of the correcting system for color mis-registration is switched so that the mechanical effect on the apparatus caused by biasing and unbiasing actions of a transfer roller and an ICL roller toward the intermediate transfer drum in each condition can be suppressed to the minimum without penalties in throughput.

Abstract: An image forming device and an image forming method for transporting a toner image on an endless belt shaped toner image transporting member. The toner image transporting member is supported by a plurality of rollers and is stretched out and made rotatable in the same direction as the recording medium is transported. The colored toner is transported on the outside of the toner image transporting member and is transferred onto stationary recording medium by an opposed image transferring roller while the rotation of the toner image transporting member is suspended. The image transferring process is repeated for the required number of colors.

Abstract: An image forming apparatus has a transfer region located between a first belt and a second belt, which belts are respectively spanned and tensioned around a plurality of rollers. A total length of the first belt is substantially equal to integral multiples of a total length of the second belt. Certain portions of the belts are deformed via plastic deformation caused by contacting the plurality of rollers. The rollers are arranged so that deformed portions of the belts do not overlap each other in the transfer region.

Abstract: A single-pass, multi-color electrostatographic duplex printer has a transfer member which is driven along a continuous path. Toner images of different colors are simultaneously electrostatically deposited in powder form in register with each other on the transfer member to form a multiple toner image. The substrate is fed into contact with the transfer member for transfer of the multiple toner image to at least one face of the substrate. The printer includes a heater for heating the multiple toner image on the transfer member in advance of the transfer of the image to the substrate.

Abstract: An image forming apparatus having an image carrying member bearing an electrostatic image wherein the electrostatic image is visualized into a toner image by a developing device. The image carrying member is arranged for transferring the toner image to an intermediate transfer element while the image carrying member and intermediate transfer element are moving at a usual speed corresponding to the speed of movement of the image carrying member during toner image development. Multiple such toner images of different colors may be transferred in this manner to form multi-color images superimposed on the intermediate transfer element for subsequent transfer to a recording medium, usually paper.

Abstract: A method of forming an electrophotographic transfer image is disclosed which provides color images free from color shear, by which toner images are completely transferred onto a receiving material without being accompanied by degradation of image quality upon the transfer, and in which a light-sensitive element can be repeatedly used without throwing the light-sensitive element away after using it only once.A method and apparatus for forming an electrophotographic transfer image comprising forming a transfer layer containing a thermoplastic resin on the surface of an electrophotographic light-sensitive element which surface has releasability in the apparatus for forming an electrophotographic transfer image, forming a toner image by an electrophotographic process on the transfer layer, and heat-transferring the toner image together with the transfer layer onto a receiving material.

Abstract: The present invention provides an image forming apparatus which includes a movable image bearing member for bearing a toner image, a movable intermediate transfer member to which the toner image on the image bearing member is electrostatically transferred at a first transfer position, and a charger for charging residual toner remaining on the intermediate transfer member after the toner image on the intermediate transfer member has been electrostatically transferred onto a transfer material at a second transfer position with polarity opposite to charging polarity of the normal toner on the image bearing member. An electric field is formed so that the residual toner charged by the charger from the intermediate transfer member onto the image bearing member and a transfer of a next toner image from the image bearing member onto the intermediate transfer member are simultaneously performed at the first transfer position.

Abstract: An image forming apparatus has an image bearing member, an image forming unit for forming a toner image on the image bearing member and having a first charge member for charging the image bearing member, a rotatable intermediate transfer member onto which the toner image on the image bearing member is transferred at a first transfer position, the toner image on the intermediate transfer member being transferred onto a transfer material at a second transfer position, and a second charge member for charging residual toner remaining on the intermediate transfer member, the second charge member charging the residual toner on the intermediate transfer member with polarity opposite to charging polarity of the first charge member for charging the image bearing member, after the toner image is transferred from the intermediate transfer member to the transfer material.

Abstract: A method of reproducing multiplex images wherein an electrostatic image is formed on an image retainer by using a common electrostatic image forming device, the electrostatic image formed on the image retainer is developed, the steps of the above are repeated to superpose a plurality of toner images on the image retainer, and the toner images is transferred on a recording paper by one step. The developings other than the first time developing are carried out in such a manner that the surface of a developer layer on a developer feeding carrier does not contact with the surface of the toner image on the image retainer.