Abstract: An image formation method and image formation apparatus capable of forming images on both sides of a recording medium even if a first image formation unit or a second image formation unit does not have the required functions. Detection is conducted to determine whether or not the first image formation unit and second image formation unit have the required functions. If, as a result of this detection, it is determined that one of the image formation units does not have the required functions, the method of forming an image on both faces of the paper is switched to the method for forming an image using only the image formation unit having the required functions.

Abstract: An image forming apparatus operable in a duplex print mode includes an image carrier and an image transferring device including a first and a second intermediate image transfer body whose surfaces are movable in contact with each other while forming a nip therebetween. Toner images are respectively transferred to opposite surfaces of a sheet using two pairs of conductive rollers that face each other via the first and second intermediate image transfer bodies at a nip. Two of the conductive rollers associated with the second intermediate image transfer body are transfer rollers respectively applied with one and the other of biases of opposite polarities.

Abstract: In a double-sided image forming apparatus and method, back-side images are developed on a first middle transfer belt prior to developing of front-side images on the first middle transfer belt, and the back-side images are transferred to a second middle transfer belt. The number of back-side images allowed to be supported at a time on the second middle transfer belt is determined. The number of back-side images are developed on the first middle transfer belt prior to developing of the same number of front-side images on the first middle transfer belt. The front-side image of the first middle transfer belt and the back-side image of the second middle transfer belt are simultaneously formed on both sides of a copy sheet.

Abstract: A color image forming apparatus comprises photoconductor drums on which toner images of each color are developed and formed; an endless intermediate transfer belt arranged in a contactable state with the photoconductor drums to run; first bias transfer rollers which perform first bias transfer in which the toner images of each color are transferred from the photoconductor drums onto the intermediate transfer belt; a second bias transfer roller which performs second transfer in which the toner images on the intermediate transfer belt are transferred onto paper; and a separation unit which, when a maximum print length of an image is below a length from a transfer point A to a transfer point B, separates the photoconductor drums and the intermediate transfer belt from each other after all first bias transfer of the toner images to be transferred on the last paper in a first print job has been completed, before second bias transfer onto the last paper is started and after second bias transfer onto paper immediate

Abstract: A photoreceptor transfers a first image to a first side of a paper, an intermediate transfer belt transfers a second image to a second side of the paper. The intermediate transfer belt also conveys the paper. A conveying unit directly conveys the paper, with the images, to a heating unit that fixes the images. The paper is slowly conveyed in the heating unit as compared to when it is conveyed by the belt.

Abstract: A printer prints on two sides of a sheet of paper having continuous pages, and discharges the paper to a postprocessor for disconnecting the paper in page units and storing the disconnected sheets of paper in a stack. Depending on whether the postprocessor has an inversion mechanism that inverts front and back sides of the paper, sides of the paper on which data for the front side of the paper and data for the back side of the paper are printed are switched. With this arrangement, even when the postprocessor does not have the inversion mechanism, the front side data is printed on the back side, and the back side data is printed on the front side thereby enabling the postprocessor to stack the disconnected sheets of paper in page units in the order of page numbers.

Abstract: A double-sided printing apparatus includes: a first printing control unit which receives printing data including page-number information per slip so as to print a slip on the obverse of a sheet by selecting printing data for printing on the obverse; and a second printing control unit which receives size information of the slip to be printed on the obverse as well as printing data for printing on the reverse of the sheet. The second printing control reads a mark printed on the obverse by using a mark reading sensor at a timing according to the size information, and compares page-number information obtained by reading the mark with that included in the printing data for printing on the reverse, so as to print, on the reverse of one page of the sheet, a slip having the page-number following that of the slip printed on the obverse of the same page.

Abstract: In an electrophotographic image process, a latent image is formed on a photosensitive drum, and a toner image is formed on the latent image. The toner image is temporarily transferred onto an intermediate image-transfer element. The photosensitive drum and the intermediate image-transfer element are brought into contact at an intended contact pressure and are rotated at a prescribed relative speed. At the contact portion, fine vibrations of the photosensitive drum and the intermediate image-transfer element, which can be caused by repeated contact and separation are prevented by controlling the contact temperature between the photosensitive member and the intermediate image-transfer element to be in the range of 15 to 60° C. A kinetic frictional deviation (a standard deviation of a kinetic frictional force) is controlled to be less than the average value of the kinetic frictional force. By suppressing the fine vibration, deviation in image transfer is prevented.

Abstract: A common polarity duplexing electrostatographic reproduction machine is provided and includes (i) a first plurality of toner image producing electrostatographic modules that each include a first image forming surface, image forming devices, and charged toner particles having a first polarity, (ii) a second plurality of toner image producing electrostatographic modules that each have a second image forming surface, image forming devices, including charged toner particles having a polarity common with the first polarity, (iii) a charged toner polarity reversing device mounted against each module of the second plurality of toner image producing electrostatographic modules for reversing a polarity of toner particles forming the second set of toner images from the first polarity to a second an opposite polarity; and (iv) a transfer device for transferring the second set of toner images having the second polarity onto a second side of the web of recording media.

Abstract: An electrophotographic image forming method is disclosed. The method comprises developing latent images each formed on a static latent image forming member by serially arranged plural image forming units each including a toner to form toner images, respectively, successively transferring the toner images onto an image support so as to form a piled up image, and fixing the piled up image by a fixing device having a rotatable heating member including a heater fixed therein and a pressing member, and in the method the toner for developing the latent image has a variation coefficient of the shape coefficient of not more than 16% and a number variation coefficient of the particle diameter distribution in number of not more than 27%.

Abstract: The disclosed embodiments are directed to a method and apparatus for duplex imaging in a tandem print engine system. The features of the disclosed embodiments include imaging a first side of a sheet in a first marking module in the system, inverting the sheet, and imaging a second side of the sheet in a second marking module in the system one pitch after N revolutions of a photoreceptor following the first side imaging.

Abstract: An image forming apparatus includes a first image bearing member, a second image bearing member, a positioning mark forming device configured to form a positioning mark on the second image bearing member, and a positioning mark detecting device configured to detect the positioning park formed on the second image bearing member. A first side visual image formed on the first image bearing member is transferred onto the second image bearing member for transferring from the second image bearing member onto a first side of a recording medium. A second side visual image formed on the first image bearing member is transferred from the first image bearing member onto a second side of the recording medium, so that the first and second side visual images are obtained on the first and second sides of the recording medium, respectively.

Abstract: An image forming apparatus of the present invention is operable in a duplex print mode for printing images on both sides of a recording medium. A toner image is transferred from a first image carrier to a second image carrier and then transferred from the second image carrier to one side of the recording medium. Subsequently, a toner image is transferred from the first image carrier to the other side of the recording medium. After the toner image has been transferred from the first image carrier to the second image carrier, the second image carrier is moved in the reverse direction to a preselected position. The apparatus of the present invention enhances productivity in the duplex print mode.

Abstract: A printer or copier operates to print a carrier material on both sides. A transfer station in the printer or copier has two transfer bands which transfer toner images onto the supporting material. A transfer corotron recharges the toner particles to a polarity for transfer to the carrier material at a transfer location. A first transfer mode provides for accumulating a plurality of toner images on the transfer band before transfer to the carrier material. A second transfer mode provides continuous transfer of the toner image to the carrier material.

Abstract: A process is proposed for the double-sided printing and/or coating of a substrate using at least one liquid or dry toner that has at least one polymer. It is provided that at least one toner layer or a first image that has at least one toner layer is transferred onto a first side of the substrate. Then, the toner is heated up to at least its glass transformation temperature, and fixed onto the substrate. In the process, the original glass transformation point of the toner shifts to a higher temperature level as a result of the cross-linking of its polymer chains, and the viscosity is increased. In a second processing step, at least one toner layer or a second image is transferred onto the second side of the substrate and heated up to a temperature that is equal to or greater than its glass transformation temperature.

Abstract: A process is proposed for the double-sided printing and/or coating of a substrate using at least one liquid or dry toner that has at least one polymer. It is provided that at least one toner layer or a first image that has at least one toner layer is transferred onto a first side of the substrate. Then, the toner is heated up to at least its glass transformation temperature, and fixed onto the substrate. In the process, the original glass transformation point of the toner shifts to a higher temperature level as a result of the cross-linking of its polymer chains, and the viscosity is increased. In a second processing step, at least one toner layer or a second image is transferred onto the second side of the substrate and heated up to a temperature that is equal to or greater than its glass transformation temperature.

Abstract: An image-forming device such as a full color printer is provided which is designed to correct the speed of an image carrier such as a sheet conveyer belt for compensating for a shift between colors. The image-forming device forms electrostatic marks on the image carrier at regular intervals and detects the marks using a sensor(s) to determine a change in speed of the image carrier based on sensor signals.

Abstract: An image forming apparatus includes an image bearing member for bearing an image, a recording material bearing member for bearing a recording material electrostatically, and a transfer member for transferring the image on the image bearing member electrostatically to the recording material borne by the recording material bearing member by being put into contact with the recording material bearing member, wherein a length of a contact area between the recording material bearing member and the transfer member is less than that of a contact area between the image bearing member and the recording material borne by the recording material bearing member in a conveyance direction of the recording material bearing member, wherein the recording material bearing member has a first layer for bearing the recording material and a second layer in contact with the transfer member in an image transfer, and wherein a surface resistivity of the first layer is lower than a surface resistivity of the second layer.

Abstract: Assuming the photosensitive drum for black as a reference, the phase of the adjacent photosensitive drum for cyan leads by about 60 deg. Similarly, the phase of the photosensitive drum for magenta leads by about 120 deg., and the phase of the photosensitive drum for yellow leads by about 180 deg. The phase of each photosensitive drum is shifted to thereby make it possible to shift the phase of driving unevenness. By shifting the phase, even the distance between adjoining transfer positions corresponding to the image forming stations is set shorter than the circumference of the photosensitive drum, the variation of each photosensitive drum due to driving unevenness with respect to the printing medium passing through the transfer position can be kept congruent with the others.

Abstract: The present invention concerns a duplex image forming apparatus, which can form images on both sides of a transfer sheet by employing an intermediate transfer element. The duplex image forming apparatus includes an image bearing member; a toner image forming section to form a toner image on the image bearing member; an intermediate transfer element, shaped like a belt, to bear the toner image transferred from the image bearing member and to convey a transfer sheet; a transfer sheet charging device to apply a bias voltage onto the transfer sheet at the charging position, so that the transfer sheet adheres onto the intermediate transfer element; a first transfer device to transfer the toner image onto the transfer sheet or the intermediate transfer element; a second transfer device to transfer the toner image borne on the intermediate transfer element onto the transfer sheet; and a control section to control a transfer current or a transfer voltage applied to the first transfer device.

Abstract: A duplex printing system including two print engines arranged in tandem for printing a first and second density patch on a print medium, at least one density sensing device adapted for measuring the density of the first and second density patches printed on the print medium by the two print engines and a control for controlling the adjustment of the print engines to enable the density and dot gain of the print output of the first and the second print engines to match. The printing system of the present invention is further characterized by the measurement of the density of the density patch printed by each print engine after the print medium has advanced through the printing system. Thus, the print medium and first and second density patches printed by each print engine is subjected to the same conditions and influences as a print job processed by the printing system.

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: An electrophotographic printer includes a print unit with a photoconductor that receives a toner image and another printing unit to produce another toner image. The printer unit is removably fastenable in a receptacle in the printer, and other identically constructed printer units are also fastenable in receptacles in the printer.

Abstract: A printer or copier and method generates toner images for transfer onto a recording medium. A latent charge image is generated on a photoconductor and is developed by the application of toner by at least one developer station to generate the toner image for transfer to the recording medium. A plurality of the developer stations are provided along the photoconductor to develop the images in color using a color separation method. A transfer band collects the color separations on top of one another to generate the overall toner image which is transferred to the recording medium. Multiple modules, each with developer stations, a photoconductor and a transfer band may be provided for one sided or two sided printing.

Abstract: An image forming apparatus has first and second image carriers that are rotatably supported and includes image forming units to form an image on respective image carriers, a conveying belt that is kept in contact with the first and the second image carriers and conveys a sheet of paper to the contact between them, transfer units to transfer the image formed on the first and second image carriers onto a sheet of paper at the contact via the conveying belt, a charger to charge the conveying belt uniformly and a paper charging roller comprising a grounded conductive member that is kept in contact with the conveying belt.

Abstract: A double-side printing apparatus for printing on double surfaces of a recording medium is constructed to prevent both an adverse influence on an image forming unit from a fixing unit and an offset of a toner image on the recording medium. The double-side printing apparatus includes a first image forming unit for forming the toner image on one surface of the recording medium, a second image forming unit, provided downstream of the first image forming unit, for forming a toner image on the other surface of the recording medium, a first fixing unit for fixing the toner image on one surface of the recording medium by a light, a second fixing unit, provided downstream of the first fixing unit, for fixing the toner image on the other surface of the recording medium, and a preventing member, provided between the first fixing unit and the second image forming unit, for preventing the light from the first fixing unit from reaching a photo sensitive body of the second image forming unit.

Abstract: A perfecting apparatus for executing prints on double surfaces of a recording medium is capable of minimizing a blank space on the recording medium. The perfecting apparatus has a first image forming unit, disposed downstream in a carrying direction of the recording medium, for forming a toner image on one surface of the recording medium, a second image forming unit, disposed upstream in the carrying direction of the recording medium, for forming the toner image on the other surface of the recording medium, a fixing unit for fixing the toner images onto the double surfaces of the recording medium, and a control unit for controlling the first and second image forming units. The control unit controls, when in one-side printing, the first image forming unit disposed downstream in the carrying direction. A distance between the fixing unit and the first image forming unit is short, and hence the blank space on the recording medium can be minimized.

Abstract: An electrophotographic has a transfer belt, a plurality of image-bearing bodies, and a plurality of transferring devices. The transfer belt is driven to run with a print medium placed thereon. The plurality of image-bearing bodies are disposed in a direction in which the transfer belt runs. Each of the plurality of transferring devices opposes a corresponding one of the plurality of image bearing bodies to form a transfer section. Each of the transferring devices selectively receives a first voltage (i.e., transfer voltage Va) and a second voltage (i.e., non-transfer voltage Vb) same as or lower than the first voltage. The first voltage is received when an image of a corresponding color is being transferred from a corresponding one of the image bearing bodies to the print medium. The second voltage is received when the image of the corresponding color is not being transferred from the corresponding one of the image bearing bodies to the print medium.

Abstract: A transport roll 1 consists of a metal roll 3 of 40 mm in diameter covered with a conductive PFA tube 2 of 10.sup.10 .OMEGA.cm in volume resistivity and 200 .mu.m in thickness. A DC voltage source 4 is connected to the metal roll. A sheet of paper 5 bearing toner images 6 and 7 on both sides thereof receives a drive force from a paper drive roll, and turns with the movement of the paper. The DC voltage source produces voltage VB1 of the same polarity as the charging polarity (positive) of the toner image 6 being in contact with the transport roll. The voltage VB1 is optimumly controlled so as to prevent the transport roll from being soiled with toner.

Abstract: An electrographic printing unit containing at least two printing units whose transfer printing points lie opposite one another is shown and described. This configuration enables high-speed duplex printing. Also disclosed is a printing unit with a photoconducting band and two exposure units located along the perimeter thereof. The exposure units superimpose two latent images each time the photoconducting band rotates.

Abstract: The present invention is a duplex printing apparatus, which is equipped with a first image forming process unit, a second image forming process unit, a fixing section, a conveyance system, and said fixing section, and a control section. In making a switch-over between printing modes (one-sided copying, both-sided copying), the control section fixes by the fixing section the unfixed toner image on the medium formed in the printing mode preceding before the switch-over and then conveys the medium by the conveyance system to a printing start position in the printing mode following after the switch-over. With this, in making a switch-over between printing modes, even when the medium is fed back, there is no possibility that the unfixed toner image formed on the medium will be disturbed. Therefore, printing quality can be maintained and printing can be performed on the medium without waste.

Abstract: There are provided a paper separating mechanism for bringing paper into a state of non-contact with a paper carrying roll; a motor for independently driving the paper carrying roll; and a switch for changing-over the paper carrying roll driving mode between a following mode and an independent driving mode so that the driving mode is changed over to the following mode and independent driving mode at the time of printing and at the time of non-printing, respectively.

Abstract: A double-sided image formation system comprises two image formation sections wherein images are supported and transported on image support transporters, for transferring the images on the image support transporters to both sides of a recording medium and forming the images thereon, density sensing means (color sensing means), when sensing the image density (color) in one image formation section, for sensing the density (color) of the image transferred from one image formation section to the image support transporter in the other image formation section, and density adjustment means (color adjustment means) for matching the image density (color) in one image formation section with that in the other.

Abstract: In accordance with the invention, a toner transfer member for electrostatography comprises a substrate and an outer surface layer comprising a material selected from the group consisting of a ceramer comprising a polyurethane silicate hybrid organic-inorganic network and a fluoropolymeric composition comprising a polyester-based polyurethane and polytetrafluoroethylene. The transfer member of the present invention is particularly useful for duplex electrostatographic copying processes; its outer surface layer substantially reduces the migration of release oil from the fusing station to the photoconductor via the transfer member, thereby ensuring high quality fused images on both sides of a receiver sheet.

Abstract: A two-sided color image forming apparatus includes: a first and second color image forming units each having an image carrier, a plurality of imagewise exposure devices and a plurality of color developing units containing respective colored toners different from each other, provided on a periphery of the image carrier; a belt-shaped intermediate transfer body passing through the first and second color image forming units for receiving a toner image formed by the second color image forming unit, wherein the first and second color image forming units are disposed downstream and upstream of a moving direction of the belt-shaped intermediate transfer body, respectively, and; a sheet pass for conveying a recording sheet onto the belt-shaped intermediate transfer body passing through between the first and second image forming units.

Abstract: A drum phase correction unit for detecting rotational positions of a plurality of photosensitive drums by means of a plurality of drum position sensors and corrects to set rotational phases of the drums to predetermined phases in such a manner that transfer positions on drum circumferential surfaces relative to a belt when employing the thus detected rotational positions as their respective references have a specific relationship including coincidence. A positional offset detection unit detects positional offsets of transfer image on recording paper attributable to the wow and flutter in a drive system including the belt and the photosensitive drums. On the basis of the thus detected positional offsets, a wow and flutter correction unit corrects the positional offsets of the transfer images on the recording paper attributable to the wow and flutter.

Abstract: A fixing system for fixing toner images onto an image printing system such that the image printing medium bearing the toner images on the obverse side and the reverse sides thereof is passed through a nip area between a pair of fixing rollers. In the nip area, a rotation speed of a first fixing roller, which comes into contact with a not-yet fixed toner image, which is formed on the obverse side of the image printing medium, is set to be substantially equal to a rotation speed of a second fixing roller, which comes in contact with a not-yet fixed toner image, formed on the reverse side of the image printing medium. This is accomplished by setting the diameters of the various layers of the first fixing roller to be equal to that of the second fixing roller. When the image printing medium is moved through the nip area by the fixing rollers, a moving speed of the upper side of the image printing medium is equal to that of the lower side thereof.

Abstract: The object of the present invention is to provide an image forming apparatus capable of producing excellent images without transfer irregularities regardless of impedance fluctuation dependent on transfer timing, and which avoids enlargement of the apparatus.The aforesaid objects are attained by the image forming apparatus of the present invention which sequentially transfers toner images formed by a plurality of image forming units onto the same transfer sheet via a plurality of transfer charging means, wherein transfer output is controlled in accordance with the change of impedance of the transfer area dependent on the timing of each transfer.

Abstract: In an apparatus and method for producing simplex prints in a single pass duplex printer, two sheets are conveyed in coinciding relationship through a common path during a print cycle. While the sheets are simultaneously conveyed through the common path, a first toner image is formed on one side of one sheet and a second toner image is formed on an opposite side of the other sheet. The toner images are simultaneously fixed on both sheets by a separate fixing station.

Abstract: A sheet carrying apparatus capable of carrying sheets at a stable speed at which a transfer belt will not be waved or wrinkled and an image forming apparatus for providing high-quality images. In opposition to a drive roll for driving the transfer belt, an opposing member magnetically attracted to the drive roll is arranged.

Abstract: A fusing station of an electrographic apparatus fixes in a single pass a duplex resinous powder color image to a support material as the support material is moved over a predetermined path through the fusing station. The fusing station employs a symmetrical fixing operation on both sides of the support material. The fusing station applies hot air to both sides of the support material in substantially equal flows. The hot air is heated by heating sources with substantially identical operational characteristics such that the flows of hot air are heated to substantially equal temperatures on both sides of the support material.

Abstract: In accordance with the present invention, an intermediate toner transfer member includes a substrate and an outer surface layer that includes a ceramer comprising a polyurethane silicate hybrid organic-inorganic network. The ceramer is formed by a crosslinking reaction between a polyurethane with reactive alkoxysilane terminal moieties and a tetraalkoxysilane. The silane-terminated polyurethane is the reaction product of one or more aliphatic polyols with terminal hydroxyl groups and an alkoxysilane-substituted alkyl isocyanate compound. Further in accordance with the present invention is a process for forming an intermediate toner transfer member having an outer surface layer comprising a polyurethane silicate hybrid organic-inorganic network.

Abstract: In a double-sided image forming apparatus for forming images on both front and back surfaces of a recording medium by two image forming units, an image position adjusting means is provided for matching the positions of the images formed on both front and back surfaces of a recording medium by the two image forming units.

Abstract: The present invention relates to an image forming apparatus which forms images on both surfaces of a sheet-shaped medium using the electrophotographic method. There is described a double-sided image forming apparatus, which includes a first and a second image bearing elements to bear toner images, a first and a second transfer units for transferring the toner images to the sheet-shaped medium from the first and the second image bearing elements, a fixing unit for fixing the toner images transferred to the sheet-shaped medium, a discharger to discharge electric charges residing on the sheet-shaped medium, a detector to detect thickness and/or stiffness data of the sheet-shaped medium, and a controller to control a first image forming mode which enables to form images on both surfaces of the sheet-shaped medium, and to control a second image forming mode which enables to form an image on only a single surface of the sheet-shaped medium.

Abstract: A fourth-unit tandem type color copier includes four photosensitive drums, a conveyor belt running, in a predetermined direction, in rolling contact with the respective drums, drum motors driving the corresponding drums, and a belt motor running the conveyor belt. Currents driving the drum motors and belt motor are so supplied as to be gradually stepped up from the starting of these motors and it is possible to lower a burden on a power source caused when the respective motors are started.

Abstract: A single pass, multi-color electrostatographic printer includes a transfer member which is driven along a continuous path. Several toner images of different colors are electrostatically deposited in powder form in registration with each other on the transfer member to form a multiple toner image thereon. A substrate is fed into contact with the transfer member. The multiple toner image is thereby transferred to at least one face of the substrate. The printer includes heaters for heating the multiple toner image on the transfer member in advance of the transfer of the image to the substrate and cooling devices for cooling the transfer member following the transfer of the multiple toner image therefrom to the substrate to a temperature below the glass transition temperature T.sub.g of the toner, prior to the deposition of further toner images on the transfer member.

Abstract: In an electrostatic both-side printing system, a first image forming unit is provided upstream of an image printing medium when viewed in the transporting direction of the image printing medium, and a second image forming unit is provided downstream of the image printing medium. A medium transporting path for transporting the image printing medium is formed between the first and the second image forming units. A first transferring unit, located facing the first image forming unit with the medium transporting path intervening therebetween, for applying no charge onto the rear side of the image printing medium, which does not face the first image forming unit. A second transferring unit being located facing the second image forming unit with the image printing medium with the medium transporting path intervening therebetween, in a state that the second transferring unit is apart from a first toner image formed on the image printing medium by the first image forming unit.

Abstract: An improved electrostatographic color printing apparatus includes an exposure unit for forming successive electrostatic latent images on the surface of a recording member in the form of an endless belt, a developing station for sequentially developing the electrostatic latent images to form toner images on the belt, and a transfer zone having electrostatic transfer stations for sequentially transferring the toner images from the belt in superposition onto a receptor sheet fed through the transfer stations while in contact with a belt section therein to produce a multicolour duplex image.

Abstract: In an image forming apparatus, a fixing device fixes a toner image transferred to a sheet, but held in an unstable state, temporarily on the sheet by a Johnson Rahbeck effect. The fixed image firmly adhere to the sheet and is free from disturbance or suffers from a minimum of disturbance.

Abstract: A single-pass, multi-color electrostatographic 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 the multiple toner image on the transfer member in advance of the transfer of the image to the substrate, and cooling capability for the transfer member following the transfer of the multiple toner image to the substrate, to a temperature below the glass transition temperature T.sub.g of the toner, prior to deposition of further toner images on the transfer member.