EP1058165A1 - Dispositif d'impression électrostatique directe où les particules de toner chargées sont amenées à proximité de la structure d'impression à l'aide d'un pistolet de pulvérisation électrostatique de poudre - Google Patents

Dispositif d'impression électrostatique directe où les particules de toner chargées sont amenées à proximité de la structure d'impression à l'aide d'un pistolet de pulvérisation électrostatique de poudre Download PDF

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Publication number
EP1058165A1
EP1058165A1 EP99201790A EP99201790A EP1058165A1 EP 1058165 A1 EP1058165 A1 EP 1058165A1 EP 99201790 A EP99201790 A EP 99201790A EP 99201790 A EP99201790 A EP 99201790A EP 1058165 A1 EP1058165 A1 EP 1058165A1
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EP
European Patent Office
Prior art keywords
toner particles
printhead structure
spray gun
printing device
charged toner
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP99201790A
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German (de)
English (en)
Inventor
Jacques c/o Agfa-Gevaert N.V. Leonard
Guido C/O Agfa-Gevaert N.V. Desie
Ludo c/o Agfa-Gevaert N.V. Joly
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Agfa Gevaert NV
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Agfa Gevaert NV
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 Agfa Gevaert NV filed Critical Agfa Gevaert NV
Priority to EP99201790A priority Critical patent/EP1058165A1/fr
Publication of EP1058165A1 publication Critical patent/EP1058165A1/fr
Withdrawn legal-status Critical Current

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    • 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
    • G03G15/34—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the powder image is formed directly on the recording material, e.g. by using a liquid toner
    • G03G15/344—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the powder image is formed directly on the recording material, e.g. by using a liquid toner by selectively transferring the powder to the recording medium, e.g. by using a LED array
    • G03G15/346—Apparatus for electrographic processes using a charge pattern involving the combination of more than one step according to groups G03G13/02 - G03G13/20 in which the powder image is formed directly on the recording material, e.g. by using a liquid toner by selectively transferring the powder to the recording medium, e.g. by using a LED array by modulating the powder through holes or a slit
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G2217/00—Details of electrographic processes using patterns other than charge patterns
    • G03G2217/0008—Process where toner image is produced by controlling which part of the toner should move to the image- carrying member
    • G03G2217/0025—Process where toner image is produced by controlling which part of the toner should move to the image- carrying member where the toner starts moving from behind the electrode array, e.g. a mask of holes

Definitions

  • This invention relates to a recording method and an apparatus for use in the process of Direct Electrostatic Printing (DEP), in which an image is created upon a receiving substrate by creating a flow of toner particles from a toner bearing surface to the image receiving substrate and image-wise modulating the flow of toner particles by means of an electronically addressable printhead structure.
  • DEP Direct Electrostatic Printing
  • toner particles are deposited directly in an image-wise way on a receiving substrate, the latter not bearing any image-wise latent electrostatic image.
  • a DEP device is disclosed in e.g. US-A-3 689 935 .
  • This document discloses an electrostatic line printer having a multi-layered particle modulator or printhead structure comprising :
  • Each control electrode is formed around one aperture and is isolated from each other control electrode.
  • Selected electric potentials are applied to each of the control electrodes while a fixed potential is applied to the shield electrode.
  • An overall applied propulsion field between a toner delivery means and a support for a toner receiving substrate projects charged toner particles through a row of apertures of the printhead structure.
  • the intensity of the particle stream is modulated according to the pattern of potentials applied to the control electrodes.
  • the modulated stream of charged particles impinges upon a receiving substrate, interposed in the modulated particle stream.
  • the receiving substrate is transported in a direction perpendicular to the printhead structure, to provide a line-by-line scan printing.
  • the shield electrode may face the toner delivery means and the control electrodes may face the receiving substrate.
  • a DC-field is applied between the printhead structure and a single back electrode on the receiving substrate. This propulsion field is responsible for the attraction of toner to the receiving substrate that is placed between the printhead structure and the back electrode.
  • printhead structures with multiple rows of printing apertures are used.
  • Such printhead structures have be disclosed in e.g. US-A-4 860 036 a printhead structure has been described consisting of at least 3 (preferentially 4 or more) rows of apertures which makes it possible to print images with a smooth page-wide density scale without white banding.
  • the main drawback of this kind of printhead structure deals with the toner particle application module, which has to be able to provide charged toner particles in the vicinity of all printing apertures with a nearly equal flux.
  • the problem of equal toner flux has been addressed in several ways (see e.g. US-A-5 040 004, US-A-5 214 451, US-A-5 136 311, EP-A-731 394 ).
  • the printing speed achievable with DEP devices does not only depends on the possibility of using a printhead structure with multiple rows of printing apertures, nor does the printing quality only depend on providing charged toner particles in the vicinity of all printing apertures with a nearly equal flux, but both printing speed and printing quality depend also on the amount of charged toner particles that is presented per unity of time in the vicinity of the printing apertures.
  • EP-A-740 224 it has been disclosed that the relative speed of rotation of the CTC (charged toner conveyor),of the magnetic brush bringing charged toner particles on the surface of the CTC and the image receiving substrate must be related to each other for bringing enough toner particles in the vicinity of the printing apertures. Also in this disclosure it has been disclosed to use a CTC with a radius that is adapted to the extension of the rows of printing apertures in the printing direction. In US-A-5 738 009 and the European equivalent EP-A-736 822 it is disclosed that when extracting the toner particles directly from a magnetic brush, without using a CTC, the speed of rotation of the magnetic brush has to be high.
  • DEP Direct Electrostatic Printing
  • DEP Direct Electrostatic Printing
  • the object of the invention is realised by providing a direct electrostatic printing device for printing images onto a receiving substrate, comprising
  • Fig. 1 shows schematically a first possible implementation of the direct spray embodiment of this invention, wherein the toner particles for image formation are directly extracted from a stream of toner particles ejected by an electrostatic spray gun.
  • Fig. 2 shows schematically a second possible implementation of the direct spray embodiment of this invention.
  • Fig. 3 shows schematically a third possible implementation of the direct spray embodiment of this invention.
  • Fig. 4 shows schematically a fourth possible implementation of the direct spray embodiment of this invention.
  • Fig. 5 shows schematically a fifth possible implementation of the direct spray embodiment of this invention.
  • Fig. 6 shows schematically a possible implementation of the spray/CTC embodiment of this invention, wherein a layer of charged toner particles is applied to a conveyor for charged toner particles by means of an electrostatic spray gun.
  • This spray gun can be used either to present a stream of charged toner particles directly in the vicinity of the printing apertures or to load, per unit of time, a large amount of charged toner particles on charged toner conveyer (CTC) from where a dense stream of toner particles is presented to the printing apertures.
  • CTC charged toner conveyer
  • the invention comprises two embodiments, a first one wherein in a DEP device a stream of charged toner particles is presented to the printing apertures direct from an electrostatic spray gun (the direct spray embodiment) and a second one wherein in a DEP device a layer of charged toner particles is applied to a CTC by an electrostatic powder spray gun (the CTC-spray embodiment).
  • Electrostatic powder spray guns are well known in the art of finishing materials by coating the materials with a dry powder instead of by a solvent based paint.
  • Electrostatic powder spray guns - herein after indicated a "spray gun” for short - are commercially available and have been disclosed in, e.g., US-A-5 622 313, US-A-5 776 249, US-A-4 653 696, US-A-4 802 625 and US-A-5 482 214.
  • a spray gun can easily be adapted to give a flat spray, therefore an even amount of particles over a large area can be provided.
  • a flat spray can be quite fast moving, this presents a disadvantage when a flat spray is used for coating materials since the oncoming particles have a relatively high speed and can easily dislodge the previously deposited particles.
  • this disadvantage turns into an advantage, since the possibility of dislodging previously deposited particles helps to keep the printhead structure clean both at the surface of the printhead, facing the spray gun, and in the printing apertures due to the impact of the particles on the printhead.
  • the toner particles are charged in the spray gun in two ways : either the gun has a high voltage charging electrode which produces a corona to charge the powder, or the gun has means to charge the powder by friction, i.e., triboelectrically. Both types of spray gun are useful in a DEP device of this invention.
  • a spray gun as toner source has further the advantage that it is easy to construct a DEP device, either of the direct spray type or the CTC-spray type, wherein only right sign toner particles arrive in the vicinity of the printing apertures and wherein the wrong sign toner particles and/or the non-charged toner particles are taken out of the flow of toner particles.
  • the receiving substrate is coupled to a DC-voltage source by bringing a back electrode kept at a DC-voltage near or in contact with the receiving substrate. It is also possible to operate a DEP device according to this invention when the receiving substrate is coupled to a DC-voltage source by first applying at least one conductive layer on a substrate, and by connecting the conductive layer to a voltage source. Thus in this case the DEP device operates without back electrode. Such a device has been described in EP-A-823 676. Also when using a DEP device according to this invention for printing PCB's (printed circuit boards) the DEP device can be operated without back electrode by coupling the conductive layer of the PCB-precursor to a voltage source. Such a method has been described in European Application 98201302 filed on April 22, 1998.
  • a DEP device wherein a spray gun forms directly a stream of charged toner particles near the printing apertures.
  • This embodiment can be implemented in various ways.
  • the spray gun is mounted so that it directs a stream of toner particles in a direction essentially perpendicular to the plane of the printing apertures and its powder outlets are arranged so that the toner particles are directed from the spray gun direct towards the printing apertures, i.e. the imaginary line drawn from the outlets of the spray gun parallel trough the particle stream, does cross the printhead structure and under a basically right angle.
  • a housing (101) with walls has a printhead structure (102) in one of the walls.
  • printing apertures (103), coupled to control electrodes (104) are present.
  • a spray gun (105) is mounted on a pivot (105a), with the powder outlets projecting a mixture of negatively charged toner particles (106a), i.e., for sake of the example, "right sign” toner, together with some non-charged toner particles (106b) and some positively charged toner particles (106c), i.e. "wrong sign” toner, directly to the printing apertures.
  • an electrode (107) is provided that is kept at a DC voltage with a negative polarity, for attracting wrong sign toners (106c), i.e. positively charged toner particles.
  • the housing is kept at a DC voltage (DC1).
  • a back electrode (108) is placed so as to define a gap, d, between the printhead structure and the back electrode.
  • An image receiving member (109) is passed through said gap in the direction of arrow A.
  • the back electrode is kept at a second DC voltage (DC2) different from DC1 so a to create an electric potential difference (an electric field) between said housing and said back electrode.
  • DC2 DC voltage
  • the negatively charged toner particles (106a) are attracted towards the back electrode and by image wise modulating the voltage applied to the control electrodes (104) by a voltage source (DC3) coupled to said control electrodes the toner particles pass the printing apertures image-wise and form a toner image on the image receiving member.
  • the toner particles that were positively charged (106c), i.e. the wrong sign toner particles, are attracted by the electrode (107) and also collected in the housing. Also the right sign toner that was not used for image formation is collected in the housing.
  • a means for moving toner particles (110) moves the toner from the housing again towards a container (not shown) and from there the toner is circulated back to the spray gun.
  • the kinetic energy given to the stream of charged toner particles by the spray gun has to be accurately controlled for avoiding that toner particles pass through printing apertures simply by virtue of the high kinetic energy, although the control electrode around the printing apertures is kept at an electric potential prohibiting the passage of charged toner particles. Also non charged toner particles are projected directly in the direction of the printing apertures and risk to pass the printing apertures in a random way.
  • the spray gun is arranged so that the imaginary line drawn from the outlets of the spray gun parallel to the particles stream, does not cross the printhead structure or when it crosses the printhead it does not so under a right angle.
  • a housing (101) with walls comprising a printhead structure (102), with printing apertures (103) and control electrodes (104) arranged in one of said walls and electrically isolated from said wall.
  • a spray gun (105) is arranged in a wall of said housing so that a particle stream containing a mixture of negatively charged toner particles (106a), i.e., for sake of the example, "right sign" toner, together with some non-charged toner particles (106b) and some positively charged toner particles (106c), i.e.
  • "wrong sign" toner is ejected in a direction essentially parallel to the wall containing the printhead structure.
  • the spray gun is movably mounted in said wall around a pivot (105a) so that it is possible, during a cleaning step, the direct the toner particles towards the printhead structure where, by the impact of the toner particles the printhead structure is cleaned.
  • an electrode (107) is provided that is kept at a DC voltage (DC4) with a polarity equal to said first polarity.
  • the housing is kept at a DC voltage (DC1).
  • DC1 DC voltage
  • a back electrode (108) is placed so as to define a gap, d, between the printhead structure and the back electrode.
  • An image receiving member (109) is passed through said gap in the direction of arrow A.
  • the back electrode is kept at a second DC voltage (DC2) different from DC1 so a to create an electric potential difference (an electric field) between said housing and said back electrode.
  • DC2 DC voltage
  • This stream comes into the electric field created by the electric potential difference
  • the negatively charged toner particles (106a) are attracted towards the back electrode by the electric potential difference
  • the toner particles that were not charged (106b) in the spray gun are not attracted towards the back electrode and are collected in the housing.
  • the toner particles that were positively charged (106c), i.e. the wrong sign toner particles, are attracted by the electrode (107) and also collected in the housing. Also the right sign toner that was not used for image formation is collected in the housing.
  • a means for moving toner particles (110) moves the toner from the housing again towards a container (not shown) and from there the toner is circulated back to the spray gun.
  • a DC-voltage source DC1
  • a further implementation of the direct spay embodiment of this invention wherein the imaginary line drawn from the outlets of the spray gun parallel to the particles stream, does not cross the printhead structure, is schematically shown in figure 3.
  • a housing (101) with walls is provided comprising a printhead structure (102), with printing apertures (103) and control electrodes (104) arranged in one of said walls and electrically isolated from said wall.
  • a spray gun (105) is arranged in a wall of said housing so that a particle stream containing a mixture of negatively charged toner particles (106a), i.e., for sake of the example, "right sign" toner, together with some non-charged toner particles (106b) and some positively charged toner particles (106c), i.e.
  • "wrong sign" toner is ejected in a direction basically perpendicular to the printhead structure (102) but the imaginary line from the outlets of the spray gun does not cross the printhead structure.
  • the stream of ejected toner particles bounces on an element (112) arranged for bending the stream of toner particles in a direction essentially parallel to the printhead structure.
  • this implementation works as the implementation shown in figure 2, but it has the advantage that the construction of the housing incorporating the spray gun and the printing apertures can be made more compact.
  • Said bouncing element (112) preferably is made of a plastic material with sufficient elasticity so that charged polymeric particles are repelled without losing kinetic energy after collision upon said bouncing element.
  • said bouncing element (112) also is provided with a surface coating that helps in tribocharging the impacting toner particles. For that reason the tribological properties of said coating is chosen on the basis of their tribo-position in the tribological range of materials, suitable for the tribobehaviour of the polymeric particles used. Excellent materials useful for coating said bouncing element can be found in the literature with regard to surface coatings used in coating carrier particles for two-component electrophotographic developing systems.
  • the rubbery material of said bouncing element (112) can also be made partially conductive (e.g.
  • FIG. 10 An other implementation of the direct spay embodiment of this invention, wherein the imaginary line drawn from the outlets of the spray gun parallel to the particles stream, does not cross the printhead structure, is schematically shown in figure 4.
  • a housing (101) with walls is provided comprising a printhead structure (102), with printing apertures (103) and control electrodes (104) arranged in one of said walls and electrically isolated from said wall.
  • a spray gun (105) is arranged in a wall of said housing so that a particle stream containing a mixture of negatively charged toner particles (106a), i.e., for sake of the example, "right sign" toner, together with some non-charged toner particles (106b) and some positively charged toner particles (106c), i.e.
  • "wrong sign" toner is ejected under a given angle (a) to the printhead structure (102) so the imaginary line from the outlets of the spray gun forms an angle a with the printhead structure and does not cross the printhead structure.
  • the stream of toner particles may reach the wall of the housing wherein the printhead structure is present simply by the kinetic energy given to the particles, but not at the location of the printhead structure.
  • the direct spray embodiment of this invention can also be implemented using more than one spray gun.
  • FIG 5 an implementation with two spray guns is shown.
  • a housing (101) with walls is provided comprising a printhead structure (102), with printing apertures (103) and control electrodes (104) arranged in one of said walls and electrically isolated from said wall.
  • a spray gun (105) is arranged in a wall of said housing so that a particle stream containing a mixture of negatively charged toner particles (106a), i.e., for sake of the example, "right sign" toner, together with some non-charged toner particles (106b) and some positively charged toner particles (106c), i.e.
  • "wrong sign" toner is ejected in a direction essentially parallel to the wall containing the printhead structure.
  • the spray guns are movably mounted in said wall around a pivot (105a) so that it is possible, during a cleaning step, the direct the toner particles towards the printhead structure where, by the impact of the toner particles the printhead structure is cleaned.
  • two electrodes (107) are provided that are kept at a DC voltage (DC4) with a polarity equal to said first polarity for taking the wrong sign toner (106c) out of the flow. Also the non charged toner particles are, at least partially, collected on these electrodes (107).
  • Electrodes are rotatably arranged so that they turn in opposite directions and a nip is formed between the two rotating electrodes.
  • the means (110) for moving the non used toner particles can then create a vacuum in the nip so that the wrong sign toners together with the non-charged toner is easily removed from the electrodes.
  • two rotating electrodes (111) coupled to a voltage source DC5 with polarity opposite to the polarity of the charge on the toner particles, are placed near the printhead structure for aiding the deflection of the "right charge" toner particles, 106a, from the streams of toner particles towards the printhead structure.
  • this implementation operates as the implementation shown in figure 2.
  • said rotating electrodes (111) can for a nip from which the excessive right-sign toner particles can be removed and recuperated.
  • DEP device wherein the charged toner particles are brought near to a printhead structure on a surface of a conveyer for charged toner particles (a Charged Toner Conveyer or CTC) are well known in art.
  • CTC Charged Toner Conveyer
  • the charged toner particles can be applied on the surface of the CTC, - which is kept at a DC voltage different from the DC voltage coupled to the receiving substrate, - by a magnetic brush.
  • a housing (101) with walls has a conveyer for charged toner particles, i.e. a CTC (117) in one of the walls, the CTC is movably mounted so as to turn in the direction of arrow B.
  • the CTC is coupled to a DC-voltage source (DC1) and to an AC-voltage source (AC1).
  • DC1 DC-voltage source
  • AC1 AC-voltage source
  • Said CTC-roller is preferably a metallic roller, e.g. a roller of aluminium with a surface coating.
  • Said surface coating can have properties tuned for optimal tribologic and electric characteristics, e.g. it can comprise carbon black and tribo-particles in a polymeric rubbery matrix.
  • a spray gun (105) is mounted, with the powder outlets (105b) projecting, for sake of the example, negatively charged toner particles (106) to the CTC.
  • a corona (113) is provided for further equalising the charge distribution of the toner particles on the CTC.
  • An electrode (115) is installed for attracting the "wrong sign" toner that would have reached the CTC, despite of the presence in the housing of an electrode (107) that is kept at a DC voltage with a negative polarity, for attracting wrong sign toners (106c), i.e. positively charged toner particles, the non-charged toner particles are projected in the housing.
  • a back electrode (108) kept at a second DC voltage (DC2) different from DC1 so a to create an electric potential difference (an electric field) between said CTC and said back electrode.
  • a second DC voltage
  • the printhead structure is arranged in such a way as to define a gap, d, between the printhead structure and the back electrode.
  • An image receiving substrate is moved through said gap, d, in the direction of arrow A.
  • a voltage source DC3 coupled to said control electrodes the toner particles pass the printing apertures image-wise and form a toner image on the image receiving member.
  • the toner particles that were positively charged (106c), i.e. the wrong sign toner particles, are attracted by the electrode (107) and collected in the housing. Also the right sign toner that was not used for image formation is collected in the housing.
  • a corona downstream from the printhead structure a corona (114) is placed and kept at a DC voltage suited to detach the toner particles, that were not used in the process from the CTC.
  • a cleaning member (116) is placed further away from the corona (114) so as to further clean the surface of the CTC.
  • the spray gun brings charged toner particles (106a) always to a clean CTC surface so that this surface provides always fresh toner particles to the surface of the CTC. This ensures that the charge distribution of the toner particles on the CTC is kept constant during printing, which results in increased reproducibility of the printing result over the time.
  • All toner particles (non-charged particles, "wrong sign” toner and “right sign” that was removed from the CTC) that were collected in the housing are moved by a means for moving toner particles (110) again towards a container (not shown), wherein the particles can be charged again and from there the toner is circulated back to the spray gun.
  • the spray guns used in this invention can be guns charging the particles with a high voltage charging electrode as well as spray guns charging the particles triboelectrically, .
  • a spray gun equipped for charging the particles with a high voltage charging electrode e.g. a GEMA MPS-1L gun (trade name of Ransburg-Gema SA, St- Gall, Switserland), said high voltage charging electrode is set to a value yielding charged toner particles with sufficient but not to high charge over mass ratio.
  • a GEMA MPS-1L gun trade name of Ransburg-Gema SA, St- Gall, Switserland
  • a direct electrostatic printing device wherein the means for providing a stream of charged toner particles proximate to a printhead structure comprises an electrostatic powder spray gun, can be used with any printhead structure known in the art, it can be used e.g. with a printhead structure as described in US-A-5 889 540, US-A-5 714 992, EP-A-812 696, EP-A-895 867, European Application 99200479 filed on February 18, 1999, European Application 99200478 filed on February 18, 1999 and European Application 99200480 filed on February 18, 1999. It can also be used with a printhead structure in mesh form as described in US-A-5 036 341.
  • a DEP-device according to this invention wherein the means for providing a stream of charged toner particles proximate to a printhead structure comprises an electrostatic powder spray gun, can be used in large format printers as described in e.g. EP-A-849 645, EP-A-849 087 and European Application 98203008 filed on September 8, 1998.
  • a DEP device according to this invention implemented in the CTC/spray embodiment can incorporate a CTC wherein the dimensions are adapted to the extension of the array of printing apertures in the printhead structure as described in, e.g., EP-A-740 224.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)
EP99201790A 1999-06-03 1999-06-03 Dispositif d'impression électrostatique directe où les particules de toner chargées sont amenées à proximité de la structure d'impression à l'aide d'un pistolet de pulvérisation électrostatique de poudre Withdrawn EP1058165A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP99201790A EP1058165A1 (fr) 1999-06-03 1999-06-03 Dispositif d'impression électrostatique directe où les particules de toner chargées sont amenées à proximité de la structure d'impression à l'aide d'un pistolet de pulvérisation électrostatique de poudre

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP99201790A EP1058165A1 (fr) 1999-06-03 1999-06-03 Dispositif d'impression électrostatique directe où les particules de toner chargées sont amenées à proximité de la structure d'impression à l'aide d'un pistolet de pulvérisation électrostatique de poudre

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0464741A2 (fr) * 1990-07-02 1992-01-08 Xerox Corporation Système d'alimentation et de chargement de toner du type cyclonique
US5159472A (en) * 1989-06-06 1992-10-27 Brother Kogyo Kabushiki Kaisha Image forming apparatus using solid image-pickup element
EP0763785A1 (fr) * 1995-09-14 1997-03-19 Agfa-Gevaert N.V. Dispositif d'impression électrostatique directe (DEP) utilisant un courant de gaz pour obtenir un nuage de rélévateur

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5159472A (en) * 1989-06-06 1992-10-27 Brother Kogyo Kabushiki Kaisha Image forming apparatus using solid image-pickup element
EP0464741A2 (fr) * 1990-07-02 1992-01-08 Xerox Corporation Système d'alimentation et de chargement de toner du type cyclonique
EP0763785A1 (fr) * 1995-09-14 1997-03-19 Agfa-Gevaert N.V. Dispositif d'impression électrostatique directe (DEP) utilisant un courant de gaz pour obtenir un nuage de rélévateur

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