WO1990001730A1 - Procede electrophotographique - Google Patents

Procede electrophotographique Download PDF

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Publication number
WO1990001730A1
WO1990001730A1 PCT/US1989/003400 US8903400W WO9001730A1 WO 1990001730 A1 WO1990001730 A1 WO 1990001730A1 US 8903400 W US8903400 W US 8903400W WO 9001730 A1 WO9001730 A1 WO 9001730A1
Authority
WO
WIPO (PCT)
Prior art keywords
image
toner
electrostatic image
developer
color
Prior art date
Application number
PCT/US1989/003400
Other languages
English (en)
Inventor
Michael Mosehauer
Yee S. Ng
Eric K. Zeise
Original Assignee
Eastman Kodak Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eastman Kodak Company filed Critical Eastman Kodak Company
Priority to DE68912299T priority Critical patent/DE68912299T2/de
Publication of WO1990001730A1 publication Critical patent/WO1990001730A1/fr

Links

Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/22—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20
    • G03G15/23—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 specially adapted for copying both sides of an original or for copying on both sides of a recording or image-receiving material
    • G03G15/231—Arrangements for copying on both sides of a recording or image-receiving material
    • G03G15/232—Arrangements for copying on both sides of a recording or image-receiving material using a single reusable electrographic recording member
    • G03G15/234—Arrangements for copying on both sides of a recording or image-receiving material using a single reusable electrographic recording member by inverting and refeeding the image receiving material with an image on one face to the recording member to transfer a second image on its second face, e.g. by using a duplex tray; Details of duplex trays or inverters
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/01—Electrographic processes using a charge pattern for multicoloured copies
    • G03G13/013—Electrographic processes using a charge pattern for multicoloured copies characterised by the developing step, e.g. the properties of the colour developers
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G13/00—Electrographic processes using a charge pattern
    • G03G13/06—Developing
    • G03G13/08—Developing using a solid developer, e.g. powder developer
    • G03G13/09—Developing using a solid developer, e.g. powder developer using magnetic brush
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/01—Apparatus for electrophotographic processes for producing multicoloured copies
    • G03G2215/0167—Apparatus for electrophotographic processes for producing multicoloured copies single electrographic recording member
    • G03G2215/0174—Apparatus for electrophotographic processes for producing multicoloured copies single electrographic recording member plural rotations of recording member to produce multicoloured copy

Definitions

  • This invention relates to color electrophotography and more specifically to a method of forming a multicolor image on the same frame or area of a photoconductive member, so ' that it may be transferred or otherwise utilized in a single step.
  • U. S. Patent 3,057,720 suggests that two color toner images can be formed consecutively on the same image frame without fixing the first image if the second toning step is not so harsh as to clean off the first toner image.
  • Three color systems are disclosed using either positive development or discharged area development. A variety of development methods are suggested.
  • Japanese Ko ai 56-144452 (1981) also discloses a process in which two or three color toner images are formed on the same frame of a photoconductive member.
  • the photoconductive member is uniformly charged, exposed and reverse developed with a toner of a first color. With the unfixed toner electrostatically adhering to the exposed areas the photoconductive member is exposed to a second image that does not overlap with the first image. That image is then developed by application of a second color toner to the newly exposed areas. The process can be repeated for more colors.
  • the resulting multicolor image is transferred to a receiving sheet in one step.
  • Toners usable in the process are limited, limiting the colors available; especially difficult to use in this process are those of lighter hue, such as yellow. It is a difficult process to establish a background controlling electrical field.
  • U.S. Patents 4,546,060; 4,473,029 and 4,531,832 describe a method of toning in which a magnetic brush applicator supplies two component developer including small hard magnetic carrier particles and electrically insulative toner to an image which moves past the development station at a predetermined velocity.
  • the brush includes a rapidly rotating core which tumbles the hard carrier particles through a development zone. The tumbling of the carrier is apparently due to the changing magnetic field which continuously flips the carrier. This process has a number of advantages in image quality, and is being used commercially. Disclosure of the Invention
  • the development process disclosed in U. S. Patents 4,546,060; 4,473,029 and 4,531,832 provide high density images at good speed without substantial damage to the prior toner images.
  • the developer is transported through the development zone by rotating an alternating-pole magnetic core within a non-magnetic shell upon which shell the developer flows through said zone, and the developer includes hard magnetic carrier particles that are sufficiently hard that they flip or tumble as they pass through the development zone.
  • Prior magnetic brushes typically include soft magnetic carrier, for example, carrier that has a coercivity substantially less than 100 gauss. As such particles are subjected to a changing magnetic field their magnetism changes with the field. This permits a brush to transport the carrier in the form of long relatively static bristles through the development zone. To apply substantial toner at medium speed, the brush generally requires relative motion with respect to the electrostatic image, commonly obtained by rotating a non-magnetic sleeve in a direction opposite to the direction of the image. The bristles have a tendency to brush at least portions of any prior toner image off the image ar.ea.
  • Fig. 1 is a schematic side illustration of an electrophotographic printer utilizing the invention
  • Figs. 2 and 3 are side views generally illustrating a magnetic brush apparatus particularly usable in the electrophotographic printer shown in Fig 1;
  • Figs. 4 and 5 are cross sections of a preferred magnetic brush usable in the printer shown in Fig. 1; and
  • Fig. 6 is a cross section of an alternative magnetic brush usable in the printer shown in Fig. 1. Best Mode of Carrying Out the Invention
  • the invention can be used in a variety of electrophotographic applications. It will be described with regard to an electronic printer.
  • an electronic printer 1 includes a photoconductive member, for example, photoconductive web 2 entrained about a series of rollers 10, 11, 12, 13, 14 and 15.
  • the photoconductive web 2 is a multilayer structure which can take various forms, but is commonly a photoconductive layer 9 on a conductive backing 8 with a suitable support.
  • the web 2 is driven by one of the rollers at a constant velocity through operative relationship with a series of electrophotographic stations.
  • a irst charging station 20 imparts a uniform charge to an image area of the photoconductive surface on the web 2 which charge may be of either polarity depending on the characteristics of the photoconductive web.
  • the uniformly charged image area is then exposed at a first electronic exposure station 30 to dissipate the charge creating a first electrostatic image.
  • the electronic exposure station 30 can be any known device which converts electrical signals into a light image, for example, a scanning laser or an LED printhead.
  • An optical exposure for example, by flash or optical scanning, can also be used.
  • the first electrostatic image is toned at a first development station 40 by the application of finely-divided marking particles which are charged to the same polarity as the original charge placed on the web by first charging station 20 to thereby tone the areas of the web that are discharged by exposure at the first electronic exposing station 30 to create a first toner image of a first color, for example, black.
  • the same image area of the web then passes into operative relation with a second charging station 22 which essentially repeats the process of the first charging station, uniformly charging the web to a polarity the same as the polarity imparted by first charging station 20.
  • the uniformly charged photoconductive member 2 is now imagewise exposed at second electronic exposure station 32 to create a second electrostatic image by imagewise discharging the photoconductor.
  • the second electrostatic image is then toned at second development station 42 by the application again of finely-divided toner of a second color having a charge the same as the uniform charge placed on the photoconductive member at second charging station 22 to create a second toner image of a second color, for example, red.
  • the process is then repeated using a third charging station 24 to lay down a uniform charge, a third electronic exposure station 34 to create a third electrostatic . image and third development station 44 to create a third toner image of a different color, for example, blue.
  • a single frame or image area on the photoconductive member contains three distinct color images, i.e., a multicolor toner image.
  • a fourth set of stations could create a fourth color in the same way.
  • the multicolor image is then transferred to a copy sheet at first transfer station 35.
  • the same process * is repeated for the next frame resulting in another multicolor toner image.
  • the copy sheet is inverted using a turnaround drum 4 and the second multicolor toner image is transferred to the side opposite that receiving the first multicolor toner image at second transfer station 36.
  • the copy sheet is then fed without disturbing the toner images to a fuser 45 which fixes both images to the copy sheet simultaneously.
  • the copy sheet is then fed to an output tray 46.
  • This particular duplexing mechanism is well-known for monocolor reproduction, see for example, U.S. Patent 4,191,465.
  • the conventional commercial approach to producing three color multicolor images is to create three consecutive images of different colors and superpose them in registration to a copy sheet at a transfer station. Superposition of the images is accomplished by either attaching the copy sheet to a rotating drum or by recirculating it back through what might conventionally be termed a duplex paper path to pick up subsequent images. In any case, multiple transfer to the paper is necessary which creates registration problems between color frames. Transfer drums for such systems are generally expensive. As mentioned above, duplex requires multiple fusing. Equally significant, for a three color reproduction, the apparatus delivers only one-third throughput that it would deliver for monocolor copies.
  • rollers 10, 11 and 12 which encoders assure the accuracy of placement of electronically controlled exposures by exposure stations 30, 32 and 34.
  • the rollers 10, 11 and 12 can also include sprockets which engage perforations in the member 2 to carefully control the location of the member during consecutive exposure.
  • Each encoder would signal the angular location of its sprocket which in turn is positioned by a perforation engaging a tooth in the sprocket, which perforation is the same for comparable portions of all three images. If the images are placed in substantially different areas of the frame and if movement of the . web is relatively constant, no encoder may be necessary. As an intermediate alternative suitable for most applications, one encoder can handle registration for all three exposure stations.
  • the photoconductive member 2 is cleaned at cleaning station 50 for reuse, as is well-known in the art.
  • the third charging station 24 exposure station 34 and toning station 44 can be eliminated.
  • Two-color systems have particular application to high speed printers in which the primary mode of operation is monocolor, i.e., black, and the second color, usually red or blue, is used to highlight certain passages of text or give a flair to letterheads, logos, and the like.
  • the first development station 40 or the second station 42 can be a larger, heavier duty development station than the other station.
  • a serious problem faced by the method and apparatus described with regard to Fig. 1 is that the second and third development stations have a tendency to disturb the previously applied toner, i.e., that applied by the first and second toning stations.
  • a magnetic brush development mechanism includes a two-component developer, one component including large magnetic carrier particles and the other smaller pigmented toner particles.
  • the mixing of the two components triboelectrically charges them to opposite polarities.
  • the magnetic characteristic of the carrier is used to transport the developer into close proximity with the electrostatic image in the presence of an electric field which urges the toner particles to some portion of the image.
  • the toner particles become charged triboelectrically to a polarity the same as the charge placed on the photoconductive member 2 and therefore are attracted in the presence of a carefully controlled electric field to the discharged portions of the electrostatic image.
  • Prior magnetic brushes typically include soft magnetic carrier, for example, carrier that has a coercivity substantially less than 100 gauss. As such particles are subjected to a changing magnetic field their magnetism changes with the field. This permits a brush to transport the carrier in the form of long relatively static bristles through the development zone. To apply substantial toner at medium speed, the brush generally requires relative motion with respect to the electrostatic image, commonly obtained by rotating a non-magnetic sleeve in a direction opposite to the direction of the image. The bristles have a tendency to brush any prior toner image off the image area.
  • a magnetic brush is illustrated which is useable in the process and apparatus illustrated in Fig. 1.
  • a photoconductive member 2 is moving in a direction indicated by the arrow and carries an electrostatic image, not shown.
  • the magnetic brush includes a rotatable magnetic core 5 which includes a plurality of magnets with alternating north and south poles arranged around the core periphery.
  • a non-magnetic shell 6 is concentric with the core 5. As is well-known in the art, if the core 5 is rotated in a counterclockwise direction as shown in Fig. 2 developer 7 is driven in a direction clockwise around the non-magnetic shell 6.
  • the non-magnetic shell 6 is driven in a clockwise direction as shown in Fig. 2, it has a tendency to move the developer 7 in a clockwise direction.
  • such apparatus uses a developer of electrically insulative toner particles and "hard" magnetic carrier particles having high minimum coercivity when magnetically saturated.
  • the developer disclosed in the Miskinis patent can be used with a large variety of toner colors and if the magnetic core is rotated at a relatively high velocity, for example, 1500 RPM, enough developer can be brought into operative relation with an electrostatic image to do high quality toning at high speeds.
  • the carrier itself can be used as part of the development electrode which gives greater control over background toning than in mono-component systems.
  • Fig. 3 the general constructional features of the brush shown in Fig. 2 are illustrated. More specifically the core 5 is mounted on bearings 60 and 61 for rotation as driven by a drive 62.
  • the core includes a ferrous material 63 with a plurality of permanent magnet strips 64 located around its periphery in alternating polarity relation.
  • the shell 6 is made of non-magnetic material such as stainless steel and is mounted for rotation and driven by a drive 65.
  • such developer comprises charged toner particles and oppositely charged carrier particles that contain a magnetic material which exhibits a predetermined high-minimum level of coercivity when magnetically saturated. More particularly such high minimum level of saturated coercivity is at least 100 gauss (when measured as described below) and the carrier particles can be binderless carriers (i.e., carrier particles that contain no binder or matrix material) or composite carriers (i.e., carrier particles that contain a plurality of magnetic material particles dispersed in a binder). Binderless and composite carrier particles containing magnetic materials complying with the 100 gauss minimum saturated coercivity levels are referred to herein as "hard” magnetic carrier particles. Coercivity levels in excess of 1000 gauss are preferred.
  • the hard magnetic carrier particles tumble in a direction that causes them to be transported in the opposite direction of the shell, which shell can be roughened to assist the tumbling and transportation process.
  • the tumbling carrier provides a "soft" brush to the electrostatic image that does not require relative movement to develop images at high speed.
  • FIGs. 4 and 5 illustrate a commercial embodiment of a development station useable in the position of any of the development stations shown in Fig. 1, but particularly useable as the second development station and the third development stations 42 and 44.
  • Photoconductive member 2 is moving from left to right as shown by the arrow in Figs. 4 and 5.
  • a housing 70 defines a sump 71 containing a two-component developer mix as described above.
  • An applicator 72 includes a core 73 5 containing magnets 74 which core and magnets are rotatable in a counterclockwise direction as illustrated by the arrow.
  • a cylindrical non-magnetic shell 75 surrounding the core is rotatable in a clockwise direction. The core 73 and the shell 75 o cooperate as described with respect to Figs.
  • a blade 25 engages the shell 5 downstream of the development zone between the shell and the photoconductive member 2 to remove unused developer material from the shell and return it to the sump.
  • Developer in sump 71 can be mixed, agitated Q and triboelectrically charged by means of a ribbon blender 76.
  • the feeding mechanism includes a cylindrical transport roller 78 which is rotatable in a clockwise direction and has an outer surface which is deeply fluted as shown in Figs. 4 and 5. The fluted surface picks up developer from the lower portion of the feeding mechanism and transports it to the applicator 72.
  • a magnet 79 inside transport roller 78 attracts developer to the roller 78 from the ribbon blender 76.
  • a gating and metering mechanism 80 includes a gating tube 81 spaced from and surrounding transport roller 78 that provide an annular space for the flow of developer. Tube 81 has an elongate relatively wide slot 48 and a much narrower elongate slot 50.
  • Slot 48 is relatively wide so that a substantial amount of developer material from sump 71 can pass through slot 48 and enter the space between tube 81 and transport roller 78 to be transported by roller 78 to the slot 50.
  • Slot 50 on the other hand is much narrower and meters the desired amount of development material to the applicator 72.
  • Tube 81 is oscillated between the positions shown in Fig. 1 and Fig. 2 to control the flow of developer material to the applicator 72.
  • Such movement can be accomplished in any suitable manner.
  • a pin 52 secured to the tube can be coupled to a solenoid 54 as shown diagrammatically at 56, so that the solenoid is effective to move the tube between these two positions.
  • the solenoid can be controlled from a logic and control unit of the printer so that it is actuated at precisely the correct time relative to movement of images on photoconductive member 2 past the development station.
  • slot 48 is between the ribbon blender and the magnet 79 so that developer from the sump can be driven by the ribbon blender through the slot.
  • Such material is attracted to roller 78 by the magnet 79.
  • the roller transports the material to the top where it is attracted toward the applicator 72 by the magnets 74 on the core 73. Thus, some of the developer will flow through the smaller slot 50 to the applicator 72.
  • the tube In order to shut off the flow of developer to the applicator, the tube is rotated approximately 6 degrees from its Fig. 4 position to its Fig. 5 position. At this time the larger slot 48 is spaced from the ribbon blender and the sump so that material from the ribbon blender and sump cannot pass through the slot into the space between the tube and the roller. Also, the smaller slot 50 is spaced from the applicator 72. When slot 50 is in its Fig. 5 position, any developer material flowing through the slot from the space between the tube and roller falls under the influence of gravity back into the sump.
  • the flow of developer can be totally cut off quite abruptly without movement of the station as a whole.
  • the gating structure can be used to '• prevent developer from contacting the photoconductive member at the unused development stations 42 and 44.
  • the embodiment shown in Figs. 4 and 5 suggests an attractive alternative to the Fig. 1 apparatus in which the exposure station 34 and the third charging station 24 are eliminated.
  • Fig. 6 shows a substantially different embodiment of a toning station useful in the method shown in Fig. 1 which is also described in U.S. Patent 4,797,704 to Hill et al.
  • toner is kept in a toner supply 142 and is fed on demand by a driven metering roller 154 to a sump area containing a rotatably driven paddle wheel 155.
  • An applicator 156 includes a magnetic core 112 substantially as described with regard to Figs. 2, 3, 4 and 5 which is rotatable in a clockwise direction.
  • a non-magnetic non-rotatable sleeve 114 controls the movement of developer from the sump up the right side, as shown in the Fig.
  • an electrical bias is applied by a bias applying means 59 to the non-magnetic shell 6.
  • This bias is picked to create an electric field which discourages the deposition of toner in the background areas.
  • the background areas are the portions of the image area that are fully charged. For example, a charge of +600 volts is placed on the photoconductive member 2 at the first charging station 20 and an LED printhead at the first exposing station 30 dissipates image areas down to +100 volts.
  • positively charged toner mixed with negatively charged carrier is applied to the electrostatic image under an electric field created by a bias on the non-magnetic sleeve of +500 volts.
  • This field will encourage positively charged toner toward the less positively charged exposed areas which are at +100 volts but will discourage disposition at the more positively charged background areas which are maintained at +600 volts.
  • This is a concept well-known in the art which varies according to the parameters of the system. For that reason, depending on the toner and carrier used, the bias at the second development station may well be optimized at a 5 different level than that of the first development station even though the polarites remain the same. Similarly, the level of charge applied at stations 20, 22 and 24 can also be varied to advantage.
  • the second and third charging stations 22 and 24 are necessary in the process only if the previous toning stations adversely affect the charge originally placed by charging station 20 or if a different charge is desired for the second imaging step.
  • the development mechanism described in this 5 invention has shown very little adverse effect on the original charge. Although it may be advantageous for highest quality work to include a small boost and leveling of the uniform charge, particularly to areas containing deposited toners, it does not appear to be 0 necessary for most applications.
  • the apparatus shown in Fig. 1 is capable of creating multicolor duplex output at full machine speed with the duplex images being formed in their natural order. This makes this particular apparatus particularly useful as a high speed color printer.

Abstract

La réalisation d'une reproduction multicolore consiste à charger uniformément un élément photoconducteur (2), exposer cet élément pour créer une première image électrostatique, développer la première image électrostatique à l'aide d'un toner d'une première couleur pour créer une première image de toner, recharger de préférence uniformément ledit élément photoconducteur, exposer l'élément chargé créant une seconde image électrostatique, développer la seconde image électrostatique par l'application de toner d'une seconde couleur aux zones exposées. On peut répéter le procédé pour n'importe quel nombre de couleurs. L'image multicolore est ensuite transférée en une seule étape sur une feuille de réception. La seconde étape et les étapes suivantes de développement sont exécutées par un dispositif de développement (42, 44) à brosses magnétiques employant des particules porteuses magnétiques dures roulées au tambour dans une zone de développement, ledit roulage n'affectant pas les images de toner précédentes. Les particules porteuses magnétiques dures ont de préférence une coercivité d'au moins 100 gauss lorsqu'elles sont magnétiquement saturées, mais idéalement une coercivité d'au moins 1000 gauss lorsqu'elles sont magnétiquement saturées. Deux images multicolores ainsi formées sont transférées sur les côtés opposés d'une feuille de copie et, les images sont fusionnées simultanément afin de produire des images multicolores duplex.
PCT/US1989/003400 1988-08-15 1989-08-09 Procede electrophotographique WO1990001730A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE68912299T DE68912299T2 (de) 1988-08-15 1989-08-09 Elektrophotographisches verfahren.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US23207388A 1988-08-15 1988-08-15
US232,073 1988-08-15

Publications (1)

Publication Number Publication Date
WO1990001730A1 true WO1990001730A1 (fr) 1990-02-22

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Application Number Title Priority Date Filing Date
PCT/US1989/003400 WO1990001730A1 (fr) 1988-08-15 1989-08-09 Procede electrophotographique

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EP (1) EP0381751B1 (fr)
JP (1) JPH03500937A (fr)
DE (1) DE68912299T2 (fr)
WO (1) WO1990001730A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5040003A (en) * 1990-06-04 1991-08-13 Eastman Kodak Company Method and apparatus for recording color with plural printheads

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6538677B1 (en) * 2000-05-17 2003-03-25 Heidelberger Druckmaschinen Ag Apparatus and method for gray level printing

Citations (8)

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Publication number Priority date Publication date Assignee Title
US4033688A (en) * 1975-02-14 1977-07-05 Agfa-Gevaert, Aktiengesellschaft Color copying apparatus
US4473029A (en) * 1983-07-01 1984-09-25 Eastman Kodak Company Electrographic magnetic brush development method, apparatus and system
US4477176A (en) * 1983-12-27 1984-10-16 Eastman Kodak Company Apparatus for producing multiple image simplex and duplex copies in a single pass
US4546060A (en) * 1982-11-08 1985-10-08 Eastman Kodak Company Two-component, dry electrographic developer compositions containing hard magnetic carrier particles and method for using the same
US4611901A (en) * 1983-07-08 1986-09-16 Kabushiki Kaisha Toshiba Electrophotographic method and apparatus
US4690096A (en) * 1986-12-22 1987-09-01 Eastman Kodak Company Magnetic brush development apparatus having a gating and metering mechanism
US4734735A (en) * 1985-08-23 1988-03-29 Konishiroku Photo Industry Co., Ltd. Image apparatus having a color separation function
WO1988005563A1 (fr) * 1987-01-27 1988-07-28 Eastman Kodak Company Appareil electrostatique en couleurs pourvu d'un organe de transfert intermediaire

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4033688A (en) * 1975-02-14 1977-07-05 Agfa-Gevaert, Aktiengesellschaft Color copying apparatus
US4546060A (en) * 1982-11-08 1985-10-08 Eastman Kodak Company Two-component, dry electrographic developer compositions containing hard magnetic carrier particles and method for using the same
US4473029A (en) * 1983-07-01 1984-09-25 Eastman Kodak Company Electrographic magnetic brush development method, apparatus and system
US4611901A (en) * 1983-07-08 1986-09-16 Kabushiki Kaisha Toshiba Electrophotographic method and apparatus
US4477176A (en) * 1983-12-27 1984-10-16 Eastman Kodak Company Apparatus for producing multiple image simplex and duplex copies in a single pass
US4734735A (en) * 1985-08-23 1988-03-29 Konishiroku Photo Industry Co., Ltd. Image apparatus having a color separation function
US4690096A (en) * 1986-12-22 1987-09-01 Eastman Kodak Company Magnetic brush development apparatus having a gating and metering mechanism
WO1988005563A1 (fr) * 1987-01-27 1988-07-28 Eastman Kodak Company Appareil electrostatique en couleurs pourvu d'un organe de transfert intermediaire

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5040003A (en) * 1990-06-04 1991-08-13 Eastman Kodak Company Method and apparatus for recording color with plural printheads

Also Published As

Publication number Publication date
DE68912299D1 (de) 1994-02-24
EP0381751B1 (fr) 1994-01-12
DE68912299T2 (de) 1994-07-07
EP0381751A1 (fr) 1990-08-16
JPH03500937A (ja) 1991-02-28

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