EP0763785B1 - Dispositif d'impression électrostatique directe (DEP) utilisant un courant de gaz pour obtenir un nuage de rélévateur - Google Patents

Dispositif d'impression électrostatique directe (DEP) utilisant un courant de gaz pour obtenir un nuage de rélévateur Download PDF

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Publication number
EP0763785B1
EP0763785B1 EP19960202316 EP96202316A EP0763785B1 EP 0763785 B1 EP0763785 B1 EP 0763785B1 EP 19960202316 EP19960202316 EP 19960202316 EP 96202316 A EP96202316 A EP 96202316A EP 0763785 B1 EP0763785 B1 EP 0763785B1
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EP
European Patent Office
Prior art keywords
toner
toner particles
dep
printhead structure
dep device
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EP19960202316
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German (de)
English (en)
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EP0763785A1 (fr
Inventor
Guido c/o Agfa-Gevaert N.V. IIE 3800 Desie
Ludo c/o Agfa-Gevaert N.V. IIE 3800 Joly
Luc c/o Agfa-Gevaert N.V. IIE 3800 Van Aken
Jacques c/o Agfa-Gevaert N.V. IIE 3800 Leonard
Frans c/o Agfa-Gevaert N.V. IIE 3800 Backeljauw
André c/o Agfa-Gevaert N.V. IIE 3800 Van Geyte
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Agfa Gevaert NV
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Agfa Gevaert NV
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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
    • G03G2215/00—Apparatus for electrophotographic processes
    • G03G2215/06—Developing structures, details
    • G03G2215/0602—Developer
    • G03G2215/0604—Developer solid type
    • G03G2215/0614—Developer solid type one-component
    • G03G2215/0621—Developer solid type one-component powder cloud

Definitions

  • This invention relates to the process of electrostatic printing and more particularly to Direct Electrostatic Printing (DEP).
  • DEP electrostatic printing is performed directly on a substrate by means of electronically addressable printheads.
  • the toner or developing material is deposited directly in an imagewise way on a substrate, the latter not bearing any imagewise latent electrostatic image.
  • the substrate can be an intermediate, in case it is preferred to transfer said formed image on another substrate (e.g. aluminum, etc..), but it is preferentially the final receptor, thus offering a possibility to create directly the image on the final receptor, e.g. plain paper, transparency, etc.... after a final fusing step.
  • the final substrate can be different materials, such as a transparent medium, opaque polymeric films, paper, etc....
  • DEP is also markedly different from electrophotography in which an additional step and additional member is introduced to create the latent electrostatic image, more specifically, a photoconductor is used and a charging/exposure cycle is necessary.
  • a DEP device is disclosed in US-P 3,689,935.
  • This document discloses an electrostatic line printer comprising a multilayered particle modulator or printhead comprising a layer of insulating material, a continuous layer of conductive material on one side of the layer of the insulating material and a segmented layer of conductive material on the other side of the layer of the insulating material.
  • the printhead comprises also at least one row of apertures.
  • Each segment of the segmented layer of conductive material is formed around a portion of an aperture and is isolated from each other segment of the segmented conductive layer. Selected potentials are applied to each of the segments of the segmented conductive layer while a fixed potential is applied to the continuous conductive layer.
  • An overall applied field projects charged particles through a row of apertures of the particle modulator (printhead) and the intensity of the particle stream is modulated according to the pattern of potentials applied to the segments of the segmented conductive layer.
  • the modulated stream of charged particles impinges upon a print-receiving medium interposed in the modulated particle stream and translated in a direction relative to the particle modulator (printhead) to provide a line-by-line scan printing.
  • the segmented electrode is called the control electrode and the continuous electrode is called the shield electrode.
  • the shield electrode faces, e.g.,the toner supply and the control electrode faces the image recording member.
  • a DC field is applied between the printhead and a backing electrode so as to attract the toner to the imaging receiving member that is placed between the printhead and the backing electrode.
  • a conveying member is provided on which a layer of toner particles is deposited and an AC voltage is applied between the toner conveying member and the continuous layer of conductive material on the printhead structure. Due to this AC voltage the toner particles "jump" between the toner conveying member and the surface of the printhead facing said toner conveying member, forming a "toner-cloud”.
  • the AC-voltage is adjusted such as to allow the toner particles to reach the printhead structure, thus enabling the overall DC voltage laid between the printhead structure and the substrate bearing member to extract said toner particles after modulation from said powder cloud.
  • the overall DC voltage propels the toner particles, after said modulation, onto the image receiving member interposed between the printhead and a backing electrode.
  • EP-A 266 960 a toner delivery system is disclosed in which a monolayer of toner is deposited on the surface of the toner conveying means using a multi-component developer (carrier/toner) and a conventional magnetic brush.
  • a multi-component developer results in a favourable charge distribution in the toner and hence in a reduction of the contamination rate of the printhead.
  • US-P 5,099,271 a DEP device is disclosed wherein the toner cloud is mechanically produced, the toner cloud is produced by using a brush with polymeric elastic hairs that scratch over a scraper blade.
  • a DEP device one may generate the toner cloud not directly from a magnetic brush, but from a charged toner conveyer (CTC) when the speed of the CTC is adapted to the travelling speed of the substrate on which is printed.
  • CTC charged toner conveyer
  • the printing speed can also be enhanced in systems, where the toner cloud is produced by a brush with polymeric elastic hairs, when the rotating speed of said brush is well adjusted, as is described in US-P 5,386,255.
  • these solutions do give good printing at high printing speed, the moving speed of the magnetic brush or the CTC becomes rather high, and does thus increase the mechanical stresses on said toner cloud producing modules.
  • a DEP device comprising a combined toner charging and delivery means, wherein the toner particles are extracted from a fluidized bed and then moved at a controlled velocity through an annular member by an air stream. By passing through this annular member the toner particles are charged and brought in the vicinity of the printing apertures in a printhead structure.
  • the moving parts are minimized, but the construction of the combined toner charging and delivery means is quite complicated, and the velocity of the air stream has to be controlled carefully since otherwise the toner charging can almost not be controlled.
  • DEP Direct Electrostatic Printing Device
  • a DEP device that comprises a printhead structure, an array of printing apertures in said printhead structure through which a particle flow can be electrically modulated by a control electrode, a toner delivery means applying a layer of charged toner particles on a charged toner conveyer (CTC) for bringing said layer of charged toner particles near said apertures, characterised in that a gas stream, near said printing apertures, is directed to said layer of charged toner particles and detaches said toner particles from said layer forming a toner cloud near said apertures.
  • CTC charged toner conveyer
  • a DEP device that comprises a printhead structure, an array of printing apertures in said printhead structure through which a particle flow can be electrically modulated by a control electrode, a toner delivery means, characterised in that said toner delivery means includes :
  • said gas stream is a stream of air.
  • toner (102) is brought from a toner container (101) via a magnetic brush (104) on to a charged toner conveyer (103).
  • the toner is part of a multi-component developer, comprising magnetic carrier particles and non-magnetic toner particles.
  • the toner on the CTC (103) is subjected to two air streams coming from the outlets (111a) and (111b).
  • the speed of streams of air and the amount of air can be independently adjusted for each outlet (111a) and (111b), by air controlling means (in the figure an air valve) (112).
  • the image is fixed to the substrate (109) by fixing means (110).
  • appropriate timing means installed on control means (112), to have either continuous or pulsating air streams.
  • the pulsation of the air streams can be independently adjusted to the desired value.
  • the pulsation of the gas streams from outlet (111a) and (111b) can be alternated, i.e. when gas is passed to the toner particles from outlet (111a), outlet (111b) is closed and vice-versa.
  • Said gas (air) streams are preferably pulsated at a frequency between 10 and 200 Hz.
  • the gas stream(s) has (have) a pressure of at least 1 10 5 Pa.
  • Printhead structure (106) shown in the first embodiment (fig 1) is made from a plastic insulating film, coated on both sides with a metallic film.
  • the printhead structure (106) comprises one continuous electrode surface, hereinafter called “shield electrode” (106b) facing in the shown embodiment the toner delivering means and a complex addressable electrode structure, hereinafter called “control electrode” (106a) around printing apertures (107), facing, in the shown embodiment, the toner-receiving member in said DEP device.
  • Said printing apertures (107) are arranged in an array structure for which the total number of rows can be chosen according to the field of application.
  • the location and/or form of the shield electrode (106b) and the control electrode (106a) can, in other embodiments of a device for a DEP method using toner particles according to the present invention, be different from the location shown in fig. 1.
  • the invention can also be used in DEP devices comprising a printhead structure comprising only control electrodes (106a) and no shield electrode (106b).
  • the invention can also be practised using a printhead structure where around every printing aperture (107), through an insulating material, one individual control electrode (106a) on one side of said insulating material and one individual shield electrode (106b) on the other side of said insulating material are present each single electrode of said individual control electrodes (106a) and each single electrode of said individual shield electrodes (106b) arranged around each aperture (107) are connected to each other via metallisation through said single aperture (107), forming a single printing electrode around each aperture (107).
  • the printhead structure used in the first embodiment can also be a so called matrix electrode as described in e.g. EP-B 390 847 and EP-B 476 030.
  • the back electrode (105) of a DEP device can be made as a planar electrode but can also be made to cooperate with the printhead structure, said back electrode being constructed from different styli or wires that are galvanically isolated and connected to a voltage source as disclosed in e.g. US-P 4,568,955 and US-P 4,733,256.
  • the back electrode, cooperating with the printhead structure can also comprise one or more flexible PCB's (Printed Circuit Board).
  • V3 is selected, according to the modulation of the image forming signals, between the values V3 0 and V3 n , on a timebasis or grey-level basis.
  • Voltage V4 is applied to the back electrode behind the toner receiving member. In other embodiments of the present invention multiple voltages V2 0 to V2 n and/or V4 0 to V4 n can be used.
  • Voltage V5 is applied to the surface of the sleeve of the magnetic brush.
  • EMBODIMENT 1 works in principle in exactly the same way, when instead of a multi-component developer, a magnetic toner is used (without the presence of carrier particles). When a magnetic toner is used CTC (103) is made magnetic and attracts directly magnetic toner from the toner container (101).
  • EMBODIMENT 1 It is also possible to use in a DEP device, according to EMBODIMENT 1 a non magnetic mono component toner that is applied to a CTC after charging of the toner by e.g. the scraping of the toner over a doctor blade.
  • the CTC does not attract the toner particles by magnetic forces, but by electrostatic forces.
  • the printhead structure (106) and the toner container (101) are built together to form a toner application module.
  • gas permeates a porous plate (114), forming the bottom of the toner container (101) and creates in the container a fluidized bed forming a toner cloud (100) of toner particles.
  • one or more coronas may be present to charge the toner particles in the fluidized bed.
  • charge injection means e.g. static or rotating blades with sharp edges can be used.
  • the toner used is replaced in toner container (101) via a toner inlet (116) that is connected with a reservoir of toner (not shown in fig 2).
  • a toner inlet (116) that is connected with a reservoir of toner (not shown in fig 2).
  • the printhead structure (106) and the toner container (101) are built together to form a toner application module as shown in fig. 2 it is not necessary to provide an inlet (116) for toner replenishment.
  • the complete module is replaced. This has the advantage that for each new toner load, a new printhead structure is used. This diminishes (or even excludes) the need for more or less complicated means for cleaning the printhead structure, as were needed in prior art DEP devices.
  • the porous plate (114) can be made from any material known in the art, e.g., porous stainless steel or porous glass as normally used in filtration applications.
  • the dimensions of the pores are chosen as a function of the diameter of the toner, the specific gravity of the toner, the dimensions of the toner container, etc to ensure an adequate formation of the fluidized bed. Typical, preferred values for the dimensions of the pores are diameters between 0.05 and 0.5 ⁇ m.
  • FIG. 3 it is schematically shown how a toner application module as shown in figure 2 can be implemented in a DEP device.
  • a printhead structure (106) is shown having control electrodes (106a) on a polymeric material around printing apertures (107), said control electrodes facing away from the toner cloud (100) in the fluidized bed contained in toner container (101).
  • the printhead structure does not comprise a shield electrode. From the fluidized bed (toner cloud (100)), toner particles in the neighbourhood of the printing apertures (107) can be attracted to the receiving substrate (109) that is transported, by transporting means (108), between the printhead structure (106), and a back electrode (105) in the direction of arrow A.
  • the image is fixed to the substrate (109) by fixing means (110).
  • the toner particles in the fluidized bed By means of corona wire(s) (115) (other charge injecting means can replace the corona wires, e.g. static or rotating blades with sharp edges).
  • the toner used during printing is replenished via opening (116) that is connected to a toner reservoir (not shown).
  • the fluidized bed is formed by a gas stream entering gas expansion chamber (113) via gas inlet (111).
  • the gas stream is controlled by control means (112) and passes via porous plate (114) to form the cloud of toner particles (fluidized bed) (100) in toner container (101).
  • Control electrode (106a) on the printhead structure makes it possible to have toner imagewise passing the apertures (107).
  • V3 is selected, according to the modulation of the image forming signals, between the values V3 0 and V3 n , on a timebasis or grey-level basis.
  • Voltage V4 is applied to the back electrode behind the toner receiving member. In other embodiments of the present invention multiple voltages V2 0 to V2 n and/or V4 0 to V4 n can be used.
  • Voltage V6 is applied to the corona wire(s) (115) to charge the toner particles in the toner container (fluidized bed).
  • the gas for formation of the fluidized bed can be any gas, but again air and nitrogen are preferred according to the present invention.
  • the module as shown in fig. 2 and fig. 3, has only one gas inlet (111). It is however possible to construct a module that basically equals the module shown in fig. 2 and fig. 3, but having more than one gas inlet. When two gas inlets are present it is preferred that both inlets are located opposite to each other. Also in this embodiment it possible to install control means (112) on both gas inlets and by appropriate timing means, installed on control means (112), to have either continuous or pulsating air streams. The pulsation of the air streams can be independently adjusted to the desired value.
  • the pulsation of the gas streams from outlet (111a) and (111b) can be alternated, i.e. when gas is passed to the toner particles from outlet (111a), outlet (111b) is closed and vice-versa.
  • Said gas (air) streams are preferably pulsated at a frequency between 10 and 200 Hz.
  • the gas stream(s) has (have) a pressure of at least 1 10 5 Pa.
  • the gas inlet or inlets at the bottom of the module of EMBODIMENT 2 can have any shape, the walls of the module can comprise means to optimize the particles flow in the gas stream.
  • toner application module as shown in fig. 2 where the printhead structure is made of isolating material comprising on one side individual control electrodes and on the other side a continuous shield electrode facing e.g. the toner container (101). In that case it is preferred that the walls of the toner container are isolated from the shield electrode and a separate voltage is applied to the shield electrode.
  • embodiment 2 of the present invention can be implemented by using be a so called matrix electrode, being a mesh of woven electrical conductors, as described in e.g. EP-B 390 847 and EP-B 476 030.
  • a mono-component developer comprising non-magnetic toner particles can be used.
  • the charging of this toner particles can proceed by simple frictional contact between the particles, the wall of toner container (101) and the gas.
  • the charging can be helped by using ionized air as gas stream for forming the fluidized bed.
  • the air can be ionized by any means known in the art, e.g. corona wires are very suitable for ionizing the air.
  • Such particles having preferably an average diameter between 20 and 100 ⁇ m, more preferably between 40 and 80 ⁇ m, makes both the formation of the fluidized bed and the charging of the toner particles easier.
  • These additional particles can be carrier particles as used in well known multi-component developers.
  • the toner particles will preferably have an average volume diameter (d v50 ) between 3 and 25 ⁇ m, preferably between 5 and 20 ⁇ m and the particles size distribution is preferably narrow.
  • the coefficient of variability, ⁇ , (i.e. the standard deviation of the distribution/d v50 ) of the volume distribution is preferably lower than 0.33, more preferably lower than 0.25.
  • toner particles suitable for use in the present invention are described in the above mentioned EP-A 675 417.
  • Very suitable toner particles, for use in combination with a printhead structure according to the present invention are toner particles, having a well defined degree of roundness. Such toner particles have been described in detail in EP-A 715 218, that is incorporated herein by reference.
  • a DEP device using a toner cloud being formed by a stream of gas, can be addressed in a way that enables it to give black and white. It can thus be operated in a "binary way", useful for black and white text and graphics and useful for classical bilevel halftoning to render continuous tone images.
  • a DEP device is especially suited for rendering an image with a plurality of grey levels.
  • Grey level printing can be controlled by either an amplitude modulation of the voltage V 3 applied on the control electrode (106a) or by a time modulation of V 3 .
  • By changing the duty cycle of the time modulation at a specific frequency it is possible to print accurately fine differences in grey levels. It is also possible to control the grey level printing by a combination of an amplitude modulation and a time modulation of the voltage V 3 , applied on the control electrode.
  • Multilevel halftoning techniques such as e.g. described in EP-A 634 862.
  • the screening method for a rendering device having restricted density resolution, disclosed in that document can be used for a DEP device according to the present invention. This enables the DEP device, according to the present invention, to render high quality images.
  • DEP devices incorporating the formation of a toner cloud by a gas stream as disclosed in the present invention, (each having a toner with a different colour) can, as is the case with any DEP device or in fact with any printing device (e.g. ink-jet printing devices, modules applying toner to an electrostatic latent image, etc), be combined in a single apparatus, making it possible to obtain a colour-printer yielding high quality images.
  • These DEP devices can be incorporated in such a single apparatus in line, in a circle, etc in the vicinity of an image receiving substrate in such a way that colour images are applied in register to said substrate.
  • the DEP devices can be ordered along to sides of a web of image receiving substrate in such a way that on both sides of said image receiving substrate colour images are formed in register in one pass.
  • a possible embodiment of positioning DEP devices in the vicinity of an image receiving member can be derived from e.g. US-P 5,173,735 directed to electrophotography. It is possible to replace the toner applying modules by DEP devices and the electrophotosensitive drum by an intermediate image receiving substrate.
  • Printing of colour images with very good register quality can be achieved with e.g. register control means comprising an encoder driven by the displacement of the image receiving substrate (in web form).
  • the encoder can e.g. be mounted on one of the rotating intermediate image receiving members. This encoder produces pulses indicative of the web displacement.
  • the moving web can accurately be synchronized with rotating intermediate image receiving members on which the separate colour images (the colour separations yellow, magenta, cyan and optionally black) are applied by different DEP devices. It is also possible to use different DEP devices that deposit toner images directly to an image receiving substrate in web form. In that case the web velocity is accurately registered with auxiliary devices.
  • Embodiments of colour printing apparatus, printing on material (substrates) in web form and using register control means, are disclosed in e.g. EP-A 629 924, EP-A 629 927 and EP 631 204.
  • the apparatus disclosed in the documents cited above, are designed as classical electrophotographic apparatus, but can be changed to printing apparatus using DEP devices.
  • the colour printing using different DEP devices can proceed on image receiving substrates in web or sheet form.
  • a colour printing apparatus using registering means and printing on sheet material is e.g. disclosed in US-P 5,119,128.
  • the DEP device according to the present invention can be combined with a classical electrographic or electrophotographic device, in which a latent electrostatic image on a charge retentive surface is developed by a suitable material to make the latent image visible.
  • the DEP device according to the present invention and the classical electrographic device are two different printing devices. Both may print images with various grey levels and alphanumeric symbols and/or lines on one sheet or substrate.
  • the DEP device according to the present invention can be used to print fine tuned grey levels (e.g. pictures, photographs, medical images etc. that contain fine grey levels) and the classical electrographic device can be used to print alphanumeric symbols, line work etc. Such graphics do not need the fine tuning of grey levels.
  • the strengths of both printing methods are combined.
  • the toner delivery means was a charged toner conveyor supplied with charged toner particles from a stationary core/rotating sleeve type magnetic brush.
  • the development assembly comprised two mixing rods and one metering roller. One rod was used to transport the developer through the unit, the other one to mix toner with developer.
  • the magnetic brush assembly (104) was constituted of the so called magnetic roller, which in this case contained inside the roller assembly a stationary magnetic core, showing nine magnetic poles of 500 Gauss magnetic field intensity and with an open position to enable used developer to fall off from the magnetic roller.
  • the magnetic roller contained also a sleeve, fitting around said stationary magnetic core, and giving to the magnetic brush assembly an overall diameter of 20 mm.
  • a scraper blade was used to force developer to leave the magnetic roller. And on the other side a doctoring blade was used to meter a small amount of developer onto the surface of said magnetic brush assembly.
  • the sleeve was rotating at 100 rpm, the internal elements rotating at such a speed as to conform to a good internal transport within the development unit.
  • the magnetic brush assembly (104) was connected to a DC-power supply with -200V (this is the V 2 , referred to hereinabove in the description of Fig. 1). Said magnetic brush was located at 650 micron from the surface of a teflon coated aluminium charged toner conveyor (103) with a diameter of 40 mm.
  • the sleeve of said charged toner conveyor was connected to an AC power supply with a square wave oscillating field of 600 V at a frequency of 3.0 kHz with 10 V DC-offset (this 10 V DC are the V 1 , referred to hereinabove in the description of Fig. 1).
  • the back electrode (105) was held at 600 V DC (this is V 4 , referred to hereinabove in the description of Fig. 1).
  • a macroscopic "soft" ferrite carrier consisting of a MgZn-ferrite with average particle size 50 ⁇ m, a magnetisation at saturation of 29 emu/g (36 ⁇ Tm 3 /kg) was provided with a 1 ⁇ m thick acrylic coating. The material showed virtually no remanence.
  • the toner used for the experiment had the following composition : 97 parts of a co-polyester resin of fumaric acid and propoxylated bisphenol A, having an acid value of 18 and volume resistivity of 5.1 x 10 16 ⁇ .cm was melt-blended for 30 minutes at 110° C in a laboratory kneader with 3 parts of Cu-phthalocyanine pigment (Colour Index PB 15:3).
  • a resistivity decreasing substance - having the following structural formula : (CH 3 ) 3 N + C 16 H 33 Br - was added in a quantity of 0.5 % with respect to the binder. It was found that - by mixing with 5 % of said ammonium salt - the volume resistivity of the applied binder resin was lowered to 5x10 14 ⁇ .cm. This proves a high resistivity decreasing capacity (reduction factor : 100).
  • the solidified mass was pulverized and milled using an ALPINE Fliessbettarnastrahlmühle type 100AFG (tradename) and further classified using an ALPINE multiplex zig-zag classifier type 100MZR (tradename).
  • the resulting particle size distribution of the separated toner measured by Coulter Counter model Multisizer (tradename), was found to be 6.3 ⁇ m average by number and 8.2 ⁇ m average by volume.
  • the toner particles were mixed with 0.5 % of hydrophobic colloidal silica particles (BET-value 130 m 2 /g).
  • An electrostatographic developer was prepared by mixing said mixture of toner particles and colloidal silica in a 10 % ratio by weight (w/w) with carrier particles.

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  • General Physics & Mathematics (AREA)
  • Printers Or Recording Devices Using Electromagnetic And Radiation Means (AREA)

Claims (11)

  1. Un dispositif DEP (impression électrostatique directe) comprenant une structure de tête d'impression (106), une matrice d'ouvertures d'impression (107) aménagées dans ladite structure de tête d'impression (106) et à travers lesquelles un flux de particules peut être modulé électriquement à l'aide d'une électrode de réglage (106a), et un moyen d'alimentation de toner (101) amenant une couche de particules de toner chargées sur une bande de transport de toner chargé (CTC) qui transporte ensuite cette couche de particules de toner chargées jusque près des ouvertures d'impression (107), caractérisé en ce qu'un courant de gaz est dirigé à proximité des ouvertures d'impression sur la couche de particules de toner chargées afin d'en souffler les particules de toner, formant ainsi un nuage de toner (100) près des ouvertures (107).
  2. Dispositif DEP selon la revendication 1, caractérisé en ce que le courant de gaz est dirigé sur la couche de particules de toner chargées présente sur la bande de transport de toner chargé à l'aide d'orifices de sortie de gaz (111a) et (111b).
  3. Un dispositif DEP (impression électrostatique directe) comprenant une structure de tête d'impression (106), une matrice d'ouvertures d'impression (107) aménagées dans ladite structure de tête d'impression (106) et à travers lesquelles un flux de particules peut être modulé électriquement à l'aide d'une électrode de réglage (106a), et un moyen d'alimentation de toner (101), caractérisé en ce que le moyen d'alimentation de toner (101) comprend :
    i) un récipient (101) contenant des particules de toner et présentant des parois étant en contact avec la structure de tête d'impression et étant électriquement isolées de cette structure de tête d'impression,
    ii) au moins un orifice d'entrée (111) servant à souffler un gaz afin de former un lit tourbillonnaire (100) de ces particules de toner d'où émane directement ledit flux de particules de toner.
  4. Dispositif DEP selon la revendication 3, caractérisé en ce que la structure de tête d'impression (106) et le récipient de toner (101) forment ensemble un module d'application de toner remplaçable.
  5. Dispositif DEP selon la revendication 3 ou 4, caractérisé en ce que les particules de toner sont des particules non-magnétiques.
  6. Dispositif DEP selon l'une quelconque des revendications 3 à 5, caractérisé en ce que les particules de toner sont chargées à l'aide d'un moyen d'injection de charge connecté à une source de courant continu alimentant le moyen d'injection de charge d'une tension électrique comprise entre 4 kV et 8 kV.
  7. Dispositif DEP selon l'une quelconque des revendications 3 à 6, caractérisé en ce que les particules de toner sont mélangées avec des particules support.
  8. Dispositif DEP selon l'une quelconque des revendications 3 à 7, caractérisé en ce que le moyen d'alimentation de toner (101) comprend deux orifices de gaz opposés.
  9. Dispositif DEP selon l'une quelconque des revendications précédentes, caractérisé en ce que le courant de gaz est pulsé.
  10. Dispositif DEP selon la revendication 9, caractérisé en ce que le courant de gaz est pulsé à une fréquence comprise entre 5 et 200 kHz.
  11. Dispositif DEP selon l'une quelconque des revendications précédentes, caractérisé en ce que le courant de gaz présente une pression d'au moins 1 105 Pa.
EP19960202316 1995-09-14 1996-08-20 Dispositif d'impression électrostatique directe (DEP) utilisant un courant de gaz pour obtenir un nuage de rélévateur Expired - Lifetime EP0763785B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19960202316 EP0763785B1 (fr) 1995-09-14 1996-08-20 Dispositif d'impression électrostatique directe (DEP) utilisant un courant de gaz pour obtenir un nuage de rélévateur

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP95202487 1995-09-14
EP95202487 1995-09-14
EP19960202316 EP0763785B1 (fr) 1995-09-14 1996-08-20 Dispositif d'impression électrostatique directe (DEP) utilisant un courant de gaz pour obtenir un nuage de rélévateur

Publications (2)

Publication Number Publication Date
EP0763785A1 EP0763785A1 (fr) 1997-03-19
EP0763785B1 true EP0763785B1 (fr) 2001-11-14

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Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0811894A1 (fr) * 1996-06-06 1997-12-10 Agfa-Gevaert N.V. Méthode d'impression d'information sur des substrats munis d'éléments de sécurité
JPH10264434A (ja) * 1997-03-25 1998-10-06 Sharp Corp 画像形成方法および装置
EP1058165A1 (fr) * 1999-06-03 2000-12-06 Agfa-Gevaert N.V. 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
DE102007027473A1 (de) 2007-06-14 2008-12-18 Manroland Ag Drucktechnisch hergestellte funktionale Komponenten

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2719575A1 (de) * 1977-05-02 1978-11-09 Siemens Ag Vorrichtung zum drucken von zeichen auf einem aufzeichnungstraeger, bei dem toner mit hilfe eines loesungsmittels geloest und im aufzeichnungstraeger fixiert wird
US4777106A (en) * 1987-02-24 1988-10-11 Dennison Manufacturing Company Electrostatic toning
US5097277A (en) * 1990-07-02 1992-03-17 Xerox Corporation Cyclonic toner charging donor
JPH06118740A (ja) * 1992-10-08 1994-04-28 Fuji Xerox Co Ltd 静電記録装置

Also Published As

Publication number Publication date
EP0763785A1 (fr) 1997-03-19

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