EP0932852B1 - Procede d'impression electrophotographique multicolore avec toner unipolaire - Google Patents

Procede d'impression electrophotographique multicolore avec toner unipolaire Download PDF

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Publication number
EP0932852B1
EP0932852B1 EP97945762A EP97945762A EP0932852B1 EP 0932852 B1 EP0932852 B1 EP 0932852B1 EP 97945762 A EP97945762 A EP 97945762A EP 97945762 A EP97945762 A EP 97945762A EP 0932852 B1 EP0932852 B1 EP 0932852B1
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EP
European Patent Office
Prior art keywords
potential
area
area element
coloured particles
colour
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.)
Expired - Lifetime
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EP97945762A
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German (de)
English (en)
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EP0932852A1 (fr
Inventor
Volkhard Maess
Martin Schleusener
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Canon Production Printing Germany GmbH and Co KG
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Oce Printing Systems GmbH and Co KG
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Publication of EP0932852A1 publication Critical patent/EP0932852A1/fr
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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
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0142—Structure of complete machines
    • G03G15/0147—Structure of complete machines using a single reusable electrographic recording member
    • G03G15/0152—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member
    • 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
    • G03G15/01—Apparatus for electrographic processes using a charge pattern for producing multicoloured copies
    • G03G15/0142—Structure of complete machines
    • G03G15/0147—Structure of complete machines using a single reusable electrographic recording member
    • G03G15/0152—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member
    • G03G15/0163—Structure of complete machines using a single reusable electrographic recording member onto which the monocolour toner images are superposed before common transfer from the recording member primary transfer to the final recording medium

Definitions

  • the invention relates to a method for electrophotographic Print a print image with multiple colors on one Carrier, wherein the printed image at least a first picture element with the color of the carrier, at least a second picture element with a second color and at least a third picture element with a third color.
  • the first picture element becomes a first surface element of a photoconductor layer assigned.
  • the photoconductor layer and a given one Electrode layer with reference potential is in one photosensitive layer system included.
  • the reference potential is usually the zero potential.
  • the second picture element becomes a second surface element and the third picture element a third surface element of the photoconductor layer assigned.
  • Such a method is e.g. from the US patent 4,078,929 known.
  • the method described there carries the Name "tri-level process".
  • a disadvantage of this method is that only toner particles of two colors in one printing process can be applied.
  • the developer stations to apply the toner particles together operated opposite polarities. The requires additional constructive measures at the developer stations, so that the developer stations are not similar are built up. So that are the individual developer stations or their components and the toners either interchangeable, and the manufacturing and operating effort is higher than with similar developer stations and like toners.
  • JP 08 044140 A is a Printing method for a multi-color printing known, in which A total exposure was carried out between two developer steps is to the potential on not yet developed Lower surfaces of the photoconductor.
  • the object of the invention is a simple method and a improved, simple printer for printing specify at least three colors with high print quality.
  • the surface elements are negative Initial potential loaded and then different exposed such that the third surface element after exposure has a third potential, the second surface element a higher amount than the third potential second potential and the first surface element one opposite the second potential is higher in terms of amount Has.
  • This different exposure is called pictorial Expose called.
  • This gradation of potential ensures that each color is assigned exactly one potential value is.
  • Another imagewise exposure step in which Area elements irradiated with different light energies can be omitted, since already after a pictorial Exposure step a clear assignment between potential values and colors.
  • the surface elements arranged near a light source in the invention After the first development step, the surface elements arranged near a light source in the invention.
  • the Arranging can e.g. by passing the surface elements the light source or by moving the light source past the surface elements can be achieved. But also a static one Arranging the surface elements opposite a light source with homogeneous light distribution is possible. there either the surface elements assigned to the print image of the layer system at the same time opposite the light source arranged or the surface elements are successively arranged opposite the light source, e.g. Surface elements, the picture elements are assigned to a line at the same time can be exposed.
  • the invention is based on the knowledge that the developer stations can be constructed in the same way if before one or more further development steps each same or at least similar potential relationships as before the first development step.
  • the potential increases to the third Area elements in terms of amount, because of these area elements charged color particles were applied. That with The third surface element covered with color particles is used in the Embodiment of the invention when arranged over the Light source with uniform light distribution considerably less exposed than the uncovered surface element because the light is not or only weakly weakened by the deposited Color particles penetrate.
  • the potential at first Surface element and on the second surface element however reduced in amount since the incident light energy is not absorbed by color particles.
  • the potential on the second surface element is the same after exposure
  • the amount of light energy is lower than the current one Potential on the third surface element. Therefore lie now similar conditions for the second surface element like before the first development step for the third Area element passed.
  • the first picture element is omitted if. all Image elements of a printed image covered with color particles become. In this case, the first picture element is all omitted or measures relating to the first surface elements.
  • the printed image contains at least one another picture element of another color.
  • the further The picture element becomes a further surface element of the photoconductor layer assigned. With image-wise exposure it will exposed further surface element so that it after Exposure has another potential, which is higher in terms of amount than the second potential and lower in amount than that possibly existing first potential.
  • Exposure has another potential, which is higher in terms of amount than the second potential and lower in amount than that possibly existing first potential.
  • the further potential becomes close to other light sources gradually reduced until the amount is less than the current potentials on those already with toner particles covered surface elements. In this state lie for that other area element similar conditions as before first or before the second development step for the third or second surface element.
  • another Development step can therefore color particles of the other Color on the further surface element similar to that in the previous development steps are deposited.
  • the developer stations are in the development steps constructed similarly. Eliminated in manufacturing constructive measures regarding different developer stations. Because the potential is relatively low is developed is z.3. the effort for the electrical Insulation in the developer stations is low. In the invention is the number of developer stations with different ones Colors only by the level of the initial potential limited because of the potentials associated with each color are at least about 300 V apart.
  • the potential on this Area element increased in amount, so the differences between the developer stations are even lower.
  • the potential is expediently increased up to a value that is slightly below the respective amount the next largest potential.
  • the invention also relates to a method in which instead of the negative initial potential is a positive initial potential is used, the respective instantaneous potentials on the surface elements instead of a negative sign have a positive sign. In addition, instead of negatively charged color particles positively charged color particles used.
  • the invention thus relates to two potential profiles on the surface elements that are only in the Distinguish the sign of the potentials. The technical Effects are the same for both potential courses.
  • the carrier can in one embodiment of the invention directly or in another embodiment of the invention printed indirectly with the help of an intermediate carrier, from which the color particles are transferred to the carrier become.
  • an intermediate carrier By using an intermediate support, the photosensitive Layer system can be spared because of the material of the intermediate carrier can be selected so that it at Contact between the intermediate beam and the layer system minimal mechanical stress on the surface of the photoconductor layer is coming.
  • a carrier e.g. sheet material or continuous paper.
  • the invention also relates to an electrophotographic Printer with the features of claim 5.
  • the above The effects mentioned regarding the procedure also apply to the printer according to the invention.
  • the printer according to the invention has a simple structure. In particular that is Layer system built from only two layers and it is only one image-wise exposure step per printed image is necessary, so that only one imagewise exposure unit with one simple control is needed.
  • the invention can be used with a dry toner that is only solid Contains color particles, or executed with a liquid toner in which the color particles are in a liquid are included.
  • FIG. 1 shows a schematic diagram of an electrophotographic Printer 10 for performing an embodiment of the method according to the invention.
  • Printer 10 has one transport device driven by a motor 12 and a shaft 14 16 for transporting an endless carrier material 18 past a printing unit 20 essentially according to a predetermined printing speed VD.
  • a printing unit 20 can be used for a changed transport single sheets can also be printed.
  • the printing unit 20 creates a multicolored toner image, e.g. with the help of a Transfer printing corona device (see FIG. 2) onto the carrier material 18 is transmitted.
  • the carrier material 18 on the printing unit 20 in Direction of an arrow indicating the direction of transport 22 After the carrier material 18 on the printing unit 20 in Direction of an arrow indicating the direction of transport 22 has been transported past, it becomes a fixing station 24 fed in which the still smearable toner image with the Backing material 18 with the help of pressure and temperature smudge-proof is merged.
  • Seen in the transport direction 22 in front of the printing unit 20 is a first deflection unit 26 arranged which the carrier material 18 of the printing unit 20th feeds.
  • Another deflection unit 28 stacks the printed one Carrier material 18 on a stack 30.
  • the carrier material 18 is carried out by a stack 32 at the beginning of the printing process the first deflection unit 26 removed. Instead of the two Stacks 30 and 32 also use rolls on which the Backing material 18 is rolled up.
  • the printing process is controlled by a print controller 34, the at least one microprocessor 36 and a memory 38 contains.
  • the microprocessor 36 works in the memory 38 stored print program and controls the printing process.
  • the pressure controller 34 also prepares Memory 38 stored image data and transfers the processed image data via a control and data bus 40 to the printing unit 20.
  • the motor 12 is via a control line 42 controlled by the pressure controller 34 so that the Carrier material 18 has a transport speed which in essentially corresponds to the printing speed VD.
  • the pressure controller 34 is connected to a via data lines 44 Input / output device 46 connected, among other things, Operating commands entered by an operator at the start of the printing process become.
  • FIG. 2 shows the printing unit 20 of the printer 10 with essential functional components.
  • the printing unit 20 contains a photoconductor 60 made of a flexible layer system exists and like a conveyor belt around two pulleys 62 and 64 is performed.
  • the deflection roller 64 is through a drive motor, not shown, driven by the pressure controller 34 and via the control and data bus 40 is controlled.
  • the printing unit 20 is one opaque chassis 66 made of a stable material surround.
  • the chassis 66 has an opening 68 at which the Photoconductor 60 passed inside the printing unit 20 becomes. Outside of the printing unit 20 is the carrier material 18 guided past the opening 68. Through the opening 68 can no light from the outside strikes the photoconductor 60 since the entire printer 10 has an opaque panel.
  • a corona device 70 is located opposite the opening 68 arranged with which one located on the photoconductor 60 Toner image is transferred to the carrier material 18.
  • the Corona device 70 is also referred to as transfer printing device.
  • the photoconductor 60 contains an electrode layer carrying zero potential 72 and one arranged approximately parallel to it Photoconductor layer 74 with the electrode layer 72 over a large area is in mechanical and electrical contact.
  • the Photoconductor 60 is directed through the deflection rollers 62, 64 an arrow 76 moves.
  • the charging device 78 contains a transverse to the transport direction 76 arranged corona device, each one surface strips of the transverse to the transport direction 76 Photoconductor 60, which is in the immediate vicinity of the charging device 78 is so charged that an initial potential VA of approximately -1200 V on the surface of the photoconductor layer 74 arises in the area of the area strip (see FIG. 3, step S1).
  • the character generator 80 contains one transverse to the direction of transport 76 arranged row of light emitting diodes, each one Area of the photoconductor lying transversely to the transport direction 76 Illuminate 60 pictorially.
  • the character generator 80 becomes controlled by the pressure controller 34 so that each Image signals for image elements of a line of the printed image at the same time converted into light signals from the light emitting diodes become.
  • the exposure of the photoconductor 60 increases this Potential on the exposed surface elements of the photoconductor 60 since the photoconductor 60 in the exposed areas conducts better, thereby removing charge carriers from the surface of the Photoconductor layer 74 to the electrode layer 72 in the area of exposed surface elements can flow off.
  • the developer station 82 stores negatively charged color particles of the color blue B using an auxiliary electrode 120 with a potential VBIAS3 on surface elements that with the third light energy were exposed. The exact mechanism of action is explained below with reference to FIG. 3 (Step S3).
  • the Loading device 84 contains one transverse to the transport direction 76 tensioned corona wire, which has a potential, the one Charging the surface of the photoconductor layer 74 in the area of the surface elements covered with blue toner particles a potential VB4 causes.
  • the potential VB4 is absolute slightly smaller than the current potential VR4 on the surface elements, which exposes with the second light energy were (see FIG. 3, step S4).
  • the strip of photoconductor 60 under consideration then turns on the total exposure unit 86 passed.
  • the total exposure unit 86 contains a laser diode that crosses in a arranged to the transport direction 76 of the photoconductor 60
  • Glass fiber array radiates light energy.
  • the fiber optic array is designed so that essentially over its entire length same light energy is emitted.
  • the light of the Total exposure unit 86 cannot by already deposited blue toner particles emit as it passes through the toner particles is absorbed. Strikes the light of the total exposure unit 86, however, on surface elements of the photoconductor layer 74, which are not yet covered with toner particles, so the potential on these surface elements is increased, i.e. it is changed in the positive direction (see FIG. 3, Step S5).
  • the developer station 88 stores negatively charged toner particles the color red R with the help of an auxiliary electrode 122 a potential VBIAS6 on surface elements that match the second light energy were exposed.
  • the exact mode of action the developer station 88 is also below explained with reference to Figure 3 (step S6).
  • the loading device 90 is essentially like the loading device 84 built.
  • the corona wire in the charger 90 has a potential to charge the surface of the Photoconductor layer 74 in the area with red toner particles covered surface elements to a potential VR7.
  • the amount of potential VR7 is slightly smaller than the current one Potential VB7 on those covered with blue toner particles Area elements (see FIG. 3, step S7).
  • the total exposure unit 92 is in the essentially constructed as the total exposure unit 86.
  • the potential is increased by the total exposure unit 92 the surface elements lowered, which are not yet with toner particles are covered. This applies to the surface elements that with no light energy or with the first light energy were exposed (see FIG. 3, step S8).
  • the developer station 94 stores negatively charged toner particles of the color green G on the one with the first light energy exposed surface elements of the photoconductor 60. there an auxiliary electrode 124 with the potential VBIAS9 is used. The exact mode of action of applying the green Toner particles are also shown in FIG. 3 below explained (step S9).
  • the eraser 98 includes a corona device 102 and an exposure unit 104 through which on the photoconductor 60 existing residual charges are removed.
  • Toner particles left after the toner image is transferred on the photoconductor c0 are left in the cleaning device 100 using a brush 106 from the photoconductor 60 removed. After being transported past the cleaning facility 100 is the strip under consideration Photoconductor 60 again in a clean initial state and has roughly the same potential at all points.
  • Figure 3 shows the potential profile on the surface of the observed Strip of photoconductor 60 in an exposure step and toner polarity.
  • On the abscissa axis is the time wasted in ten consecutive Time steps S1 to S10 is divided.
  • On the ordinate axis is the potential on the surface of the photoconductor layer 74 regarding the potential on the electrode layer 72 shown.
  • step S1 the potential on the surface of the Photoconductor layer 74 by the action of the charging device 78 shifted in the negative direction to the initial potential VA, which, as already mentioned, has the value of -1200 V.
  • step S2 the image-wise exposure is carried out using the Character generator 80, whereby the potential curve shown on the surface of the photoconductor layer 74 sets. Surface elements that are not covered with toner particles later should not be exposed.
  • the Potential VA increases on these surface elements in the course of step S2 only slightly by one that cannot be suppressed Self-discharge of the photoconductor 60 to a value VW2.
  • the potential on the surface elements with the The first light energy to be exposed increases to a value VG2 of approximately -800 V.
  • the potential on the surface elements, which are exposed with the second light energy increases in Course of step S2 to a potential value VR2 of about -400 V.
  • the potential on the surface elements with the third light energy were exposed increases in step S2 approximately to a potential value VB2 of approximately -100 V.
  • step S3 negative blue toner particles are replaced by the Developer station 82 deposited.
  • the auxiliary electrode 120 in near the photoconductor 60 has the auxiliary potential VBIAS3 from about -390 V.
  • the negatively charged blue toner particles Because the potential VBIAS3 is higher than the potentials VW2, VG2 and VR2 these potentials with respect to the potential VBIAS3 negative.
  • negatively charged blue toner particles can only show up of an area that is deposited with respect to the potential VBIAS3 has higher or positive potential. That is true only for surface elements that in step S2 with the third Light energy were exposed. As a result, on this Surface elements deposited the blue toner particles.
  • step S4 the current potential VB4 is on the surface of the surface elements covered with blue toner particles reduced to approximately -380 V with the aid of the charging device 84.
  • the self-discharge of the photoconductor 60 increases the Potentials VW3, VG3 and VR3 in step S4 to the potentials VW4, VG4 or VR4.
  • step S5 by the total exposure unit 86 emitted light, the potential VW4, VG4 or VR4 the surface elements not covered with toner particles in each case by about 400 V to the potentials VW5, VG5 or VR5 elevated.
  • the potential on surface elements in step S2 were exposed with the second light energy further exposure in step S5 to the highest current one Potential VR5 on one of the surface elements in step S5.
  • the potential VB4 increases slightly due to the Self-discharge of the photoconductor 60 to the potential VB5.
  • step S6 similar to step S3 toner particles are applied to the surface elements that have a potential greater than -380 V. However this now affects the surface elements in step S2 were exposed with the second light energy.
  • step S6 negative red toner particles are replaced by the Developer station 88 deposited.
  • the auxiliary electrode 122 in the immediate vicinity of the photoconductor 60 has the auxiliary potential VBIAS6 of about -370V. Located on the auxiliary electrode 122 the negatively charged red toner particles. Because the potential VBIAS6 is higher than the potentials VW6, VG6 and VB6, these potentials are negative with respect to the potential VBIAS6. However, the negatively charged red toner particles can only be deposited on an area that is currently a with respect to the potential VBIAS6 higher or positive potential Has. This only applies to surface elements that are in the Step S2 were exposed to the second light energy. As a result, the red ones become on these surface elements Toner particles deposited.
  • step S7 the potential VR7 on the surface of the surface elements covered with red toner particles with the help charger 90 is reduced to about -360 V.
  • the Self-discharge of the photoconductor 60 increases the potential VW6, VG6 or VB6 in step S7 to the potentials VW7, VG7 or VB7.
  • step S8 by the total exposure unit 92 emitted light, the potential VW7 or VG7 on the surface elements not covered with toner particles about 400 V to the potentials VW8 or VG8.
  • the potential on surface elements that in step S2 with the first Light energy has been exposed by further exposure in step S8 to the highest potential VG8 on one of the Area elements in step S8.
  • the potentials VB7 and VR7 increase slightly due to the self-discharge of the Photoconductor 60 to the potentials VB8 and VR8. Between Potentials VR8 and VG8 there is a difference of about 400 V, so that in step S9 similar to that in steps S3 and S6 toner particles applied to the surface elements that have a potential greater than -360 V. However this now affects the surface elements in step S2 were exposed with the first light energy.
  • step S9 negative green toner particles are replaced by the Developer station 94 deposited.
  • the auxiliary electrode 124 in near the photoconductor 60 has the auxiliary potential VBIAS9 from about -350 V.
  • the auxiliary electrode 124 contains the negatively charged green toner particles.
  • Analog to the im Electrical conditions described in step S3 or S6 the negative toner particles on the sheet elements applied in step S2 with the first light energy were exposed.
  • By depositing the negatively charged green toner particles reduce the potential to the surface elements covered with green toner particles onto one Potential value VG9. Increase the potentials VW8, VB8 and VR8 due to the self-discharge of the photoconductor 60 on the Potential values VW9, VB9 or VR9.
  • step S10 the strip of the photoconductor under consideration 60 passed the transfer station 96.
  • the transfer station 96 contains a corona device which is a transhipment of the layer system to about -1200V. When transporting past, the Potentials on all surface elements significantly reduced.
  • a step SH not shown in FIG by the action of the positively charged corona device 70 the toner particles of sheet elements covered with toner particles essentially keeping their location transferred to each other on the carrier material 18. Doing so increases the potential on the surface elements of the photoconductor 60 to about -400 V. The remaining charge on the Photoconductor 60 is removed by the eraser 98 that the photoconductor 60 on its surface after passing the quenching device 98 has a potential value of approximately 0 V Has.
  • Figure 4 shows the state of surface elements of the photoconductor 60 at the end of steps S1 to S11.
  • Part a of Figure 4 shows a print image 140, the four picture elements 142 to 148 contains.
  • the picture element 142 has the color blue B, which in Figure 4 is represented by a horizontal hatching.
  • the picture element 144 has the color red R, which is shown in FIG vertical hatching is shown.
  • the picture element 146 has the color green G, which in Figure 4 by an inclined Hatching is shown, the hatching lines of about 45 ° are arranged with respect to the horizontal.
  • the picture element 148 has the color white W (color of the carrier material 18), the in Figure 4 is represented by hatching, the Hatch lines about an angle of 135 ° with respect to Are aligned horizontally.
  • Part b shows a strip-shaped section 150 of the photoconductor 60.
  • Section 150 is transverse on photoconductor 60 arranged to the transport direction 76.
  • Figure 4 the Section 150 shown in plan view, with the photoconductor layer 74 points upwards.
  • surface elements 152 to 158 on the surface of the Photoconductor 60 assigned the picture elements 142 to 148.
  • the surface element 152 is assigned to the image element 142.
  • the Picture element 144, 146 or 148 becomes surface element 154, 156 and 158 assigned. The assignment is made so that neighboring Area elements also neighboring picture elements of the Print image 140 are assigned.
  • Charging device 78 on each of the surface elements 152 to 158 generates the initial potential VA.
  • Part c of FIG. 4 shows the state of the surface elements 152 to 158 after imagewise exposure in step S2.
  • the surface element 152 has the greatest third light energy, takes place in the area of the surface element 152 through the Incidence of light well conductive photoconductor layer 74 a charge reduction instead, as a result of which the potential VB2 on the Surface of the surface element 152 adjusts.
  • the surface element 154 is exposed to the second light energy, the is lower than the third light energy.
  • the potential VR2 which is lower than the potential VB2 on the surface of the surface element 154.
  • On the Surface of the surface element 156 turns after the Expose with the first light energy in step S2 Potential VG2.
  • the potential VG2 is lower than the potential VR2.
  • the surface element 158 is at pictorial exposures not illuminated. As a result itself on the surface of the surface element 158 at the end of the imagewise exposure step S2 the potential VW2, that is only slightly above the initial potential VA.
  • a surface element which is not covered with toner particles and which has the highest potential at the end of one of the steps S1 to S11 is identified by an asterisk in the top right corner of the respective surface element.
  • the surface element 152 has the greatest potential.
  • Part d of FIG. 4 shows the surface potentials on the surface elements 152 to 158 at the end of step S3.
  • section 150 is transported past developer station 82.
  • blue toner particles are only deposited on the surface of the surface element 152, so that this surface element is completely covered with blue toner particles (horizontal hatching).
  • Part e of FIG. 4 shows the surface elements 152 to 158 End of step S5 in which section 150 is even was exposed. Due to the even exposure it happens a potential increase on the surface of the surface elements 154, 156 and 158 that are not covered with toner particles because, as already mentioned, the incident light Resistance of the photoconductor layer 74 is reduced and a partial one Load carrier compensation between load carriers on the Surface of these surface elements and charge carriers in the Electrode layer 72 takes place. At the end of step S5 the surface element 154 has the largest on its surface Potential.
  • Part f of FIG. 4 shows the surface elements 152 to 158 am End of step S6.
  • the Section 150 transported past developer station 88. Red toner particles are deposited for the reasons mentioned above on the surface element 154 (vertical hatching). The surface elements 152 and 154 are thus with toner particles covered.
  • Part g of FIG. 4 shows the surface elements 152 to 158 am End of step S8, in which the section 150 for the second Times evenly exposed.
  • step S8 Area elements 156 and 158.
  • the potential on the area elements 156 and 158 each increase in step S8 400 V increased.
  • the surface element has 156 the greatest potential on its surface.
  • Part h of FIG. 4 shows the surface elements 152 to 158 am End of step S9.
  • section 150 transported past developer station 94. In doing so green toner particles on the for the above reasons Surface element 152 deposited (45 ° hatching), so that now the surface elements 152, 154 and 156 covered with toner particles are.
  • Part i of FIG. 4 shows a section 160 of the carrier material 18 at the end of step S11.
  • the toner particles on the Section 150 are essentially below in step S11 Maintaining their mutual position on section 160 of the carrier material 18 transferred.
  • the carrier material 18 has as already mentioned, the color white W (135 ° hatching), so that the print image 140 as a result of the described method with the picture elements 142 to 148 on the section 160 of the Carrier material 18 was printed.
  • a picture element has e.g. when printing with the printer 10 at a resolution of 600 pixels per 25.4 mm of approximately 0.042 mm, so that the representations in FIG. 4 a strong magnification with a magnification factor of is about 200.
  • the human eye can see the pixels an ordinary reading distance of about 30 cm dissolve individually. This results in color mixing effects.
  • the blue picture element 142 and the red picture element 144 result e.g. the mixed color perceived by the eye violet.
  • n colors by the initial potential VA approximately equal to n times the potential requirement for one individual development step is selected. You also have to in the imagewise exposure at least n different Light energies can be generated per picture element, so that n + 1 different potentials can be generated.
  • the Steps S7 to S9 become n-3 times after step S9 repeated.
  • the letter n is a natural number, which can take the values 4, 5, etc.
  • auxiliary electrode with the potential VBIAS3 'of about Deposits +390 V.
  • a Developer station for positively charged black toner particles used.
  • the auxiliary electrode when applying the black Toner particle has an auxiliary potential VBIAS6 'of approximately +370 V.
  • the charger 90, the total exposure unit 92 and the developer station 94 is omitted in the printing unit 20 ', because only two colors are printed.
  • the potential curve shown in FIG. 5 differs of the potential curve of Figure 3 in principle in that the Signs of the potentials reversed compared to FIG. 3 and that only three potential curves are shown. Taking into account the signs, those based on FIG. 3 apply statements made also for the potential courses of the figure 5. Instead of steps S1 to S6 there are now steps S1 'to S6'. Instead of the potential VA, a is shown in FIG potential VA 'of smaller amount with opposite, positive sign used. In addition, the sign changed potentials VR2 ', VR3', VR4 ', VR5' or VR6 'to the Place the potentials VB2, VB3, VB4, VB5 and VB6.
  • VR2, VR3, VR4, VR5 and VR6 occur in the Signs of changed potentials VK2, VK3, VK4, VK5 or VK6.
  • the potentials VW2 ', VW3', VW4 ', VW5 'or VW6' replace the potentials VG2, VG3, VG4, VG5 or VG6 and describe the potential curve on surface elements the photoconductor layer 74, on which, however no toner particles are deposited.

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  • General Physics & Mathematics (AREA)
  • Color Electrophotography (AREA)

Claims (6)

  1. Procédé pour l'impression électrophotographique d'une image d'impression (140) polychrome sur un support (18), dans lequel :
    l'image d'impression (140) comporte au moins un premier élément d'image (148) de la couleur (W) du support (18), au moins un deuxième élément d'image (144) d'une deuxième couleur (R) et au moins un troisième élément d'image (142) d'une troisième couleur (B) et au moins un quatrième élément d'image (146) d'une autre couleur (G),
    un premier élément de surface (158) d'une couche photoconductrice (74) est associé au premier élément d'image (148), un deuxième élément de surface (154) est associé au deuxième élément d'image (144), un troisième élément de surface (152) est associé au troisième élément d'image (142) et un autre élément de surface (156) est associé à l'autre élément d'image (146),
    la couche photoconductrice (74) et une couche conductrice (72) formant électrode à un potentiel de référence donné sont contenues dans un système de couches (60)
       et dans lequel les étapes suivantes sont réalisées successivement
    S1) les éléments de surface (152 à 158) sont portés à un potentiel de départ (VA) d'une première polarité (étape S1),
    S2) les éléments de surface (152 à 158) sont exposés différemment à la lumière de façon que, après l'exposition à la lumière, le troisième élément de surface (152) soit à un troisième potentiel (VB2), le deuxième élément de surface (154) soit à un deuxième potentiel (VR2) plus élevé en valeur absolue que le troisième potentiel (VB2), l'autre élément de surface (156) soit à un autre potentiel (VG2) plus élevé en valeur absolue que le deuxième potentiel (VR2), et le premier élément de surface (158) soit à un premier potentiel (VW2) plus élevé en valeur absolue que l'autre potentiel (VG2) (étape S2),
    S3) les éléments de surface (152 à 158) sont développés avec des pigments colorés de la troisième couleur (B) (étape S3),
       les pigments colorés de la première polarité et de la troisième couleur (B) étant déposés sur le troisième élément de surface (152) en utilisant une première électrode auxiliaire (120) qui est à un premier potentiel auxiliaire (VBIAS3) qui est supérieur en valeur absolue au potentiel instantané (VB3) du troisième élément de surface (152) et inférieur en valeur absolue au potentiel instantané (VR3) du deuxième élément de surface (154),
    S4) les éléments de surface sont agencés à proximité d'un dispositif d'élévation de potentiel (84) pour élever en valeur absolue le potentiel du troisième élément de surface (152) après le dépôt des pigments colorés de la troisième couleur (B),
    S5) les éléments de surface (152 à 158) sont agencés à proximité d'une source lumineuse (86) à diffusion sensiblement uniforme de la lumière (étape S5),
    le troisième élément de surface (152) recouvert de pigments colorés étant bien moins exposé à la lumière que le premier élément de surface non recouvert (158), que l'autre élément de surface non recouvert (156) et que le deuxième élément de surface non recouvert (154),
    et le potentiel instantané (VR5) du deuxième élément de surface (154) étant abaissé en valeur absolue à un potentiel qui est inférieur en valeur absolue au potentiel instantané (VB5) du troisième élément de surface (152),
    S6) les éléments de surface (152 à 158) sont développés avec des pigments colorés de la deuxième couleur (R) (étape S6),
       les pigments colorés de la première polarité et de la deuxième couleur (R) étant déposés sur le deuxième élément de surface (154) en utilisant une deuxième électrode auxiliaire (122) qui est à un deuxième potentiel auxiliaire (VBIAS6) qui est supérieur en valeur absolue au potentiel instantané (VR6) du deuxième élément de surface (154) et inférieur en valeur absolue au potentiel instantané (VB6) du troisième élément de surface (152) et au potentiel instantané (VW6) du premier élément de surface (158),
    S7) les éléments de surface sont agencés à proximité d'un autre dispositif d'élévation de potentiel (90) pour élever en valeur absolue le potentiel du deuxième élément de surface (154) après le dépôt des pigments colorés de la deuxième couleur (R),
    S8) les éléments de surface (152 à 158) sont agencés à proximité d'une autre source lumineuse (92), l'autre élément de surface non recouvert (156) étant à chaque fois bien plus exposé à la lumière que les éléments de surface recouverts de pigments colorés,
       et le potentiel de l'autre élément de surface (156) étant abaissé en valeur absolue à un potentiel (VG8) qui est inférieur en valeur absolue au potentiel instantané (VR8) du deuxième élément de surface (154),
    S9) les éléments de surface (152 à 158) sont développés avec des pigments colorés de l'autre couleur (G),
       les pigments colorés de la première polarité et de l'autre couleur (G) étant déposés sur l'autre élément de surface (156) en utilisant une autre électrode auxiliaire (124) qui est à un autre potentiel auxiliaire (VBIAS9) qui est supérieur en valeur absolue au potentiel instantané de l'autre élément de surface (156) et inférieur en valeur absolue au potentiel instantané des autres éléments de surface.
  2. Procédé selon la revendication 1, caractérisé en ce que, après le développement des éléments de surface avec des pigments colorés de l'autre couleur (étape S9), les pigments colorés déposés sont portés sensiblement à un même potentiel (étape S10).
  3. Procédé selon l'une des revendications précédentes, caractérisé en ce que les pigments colorés déposés sont transférés simultanément de la couche photoconductrice (74) au support (18) en maintenant sensiblement leur position les uns par rapport aux autres.
  4. Procédé selon la revendication 1 ou 2, caractérisé en ce que les pigments colorés déposés sont transférés sur un support intermédiaire en maintenant sensiblement leur position les uns par rapport aux autres,
    et en ce que les pigments colorés sont transférés du support intermédiaire au support (18) en maintenant sensiblement leur position les uns par rapport aux autres.
  5. Appareil d'impression électrophotographique (10), en particulier pour la mise en oeuvre du procédé selon l'une des revendications 1 à 3, comportant
    un système de couches photosensibles (60) qui comprend une couche conductrice (72) formant électrode à un potentiel de référence donné et une couche photoconductrice (74),
    un dispositif d'élévation de charge (78) pour engendrer un potentiel de départ (VA, VA') sur la couche photoconductrice (74),
    un dispositif d'exposition à la lumière (80) pour exposer la couche photoconductrice (74) pour obtenir une image,
    une première station de développement (82) pour déposer des pigments colorés d'une polarité et d'une couleur (B) sur le système de couches (60),
    au moins deux unités d'exposition totale à la lumière (86, 92) pour exposer uniformément à la lumière le système de couches (60),
    au moins deux unités d'élévation de potentiel (84, 90) pour élever en valeur absolue seulement le plus faible potentiel en valeur absolue correspondant du système de couches (60),
    et au moins deux autres stations de développement (88, 94) pour déposer des pigments colorés de la polarité et d'une autre couleur (R, G) sur le système de couches (60), caractérisé en ce que les unités d'exposition totale à la lumière (86, 92) et les unités d'élévation de potentiel ainsi que les autres stations de développement (88, 94) sont agencées de façon qu'une bande de surface du système de couches (60) disposée perpendiculairement à la direction de défilement du système de couches (60) passe à chaque fois tout d'abord par un dispositif d'élévation de potentiel (84, 90), puis par une unité d'exposition totale à la lumière (86, 92), et enfin par une autre station de développement (88, 94).
  6. Appareil d'impression selon la revendication 5, caractérisé en ce qu'il est prévu une station de transfert de charge (96) pour porter les pigments colorés déposés sensiblement à un même potentiel,
    et/ou un dispositif de transfert (70) pour transférer les pigments colorés déposés du système de couches (60) sur un support (18),
    et/ou un dispositif d'effacement (98) pour effacer une image due à une charge résiduelle sur le système de couches (60),
    et/ou un dispositif de nettoyage (100) pour nettoyer le système de couches (60).
EP97945762A 1996-10-17 1997-10-16 Procede d'impression electrophotographique multicolore avec toner unipolaire Expired - Lifetime EP0932852B1 (fr)

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DE19642891 1996-10-17
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EP3039489B1 (fr) * 2013-08-29 2020-08-05 HP Indigo B.V. Impression électrophotographique liquide

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US4078929A (en) 1976-11-26 1978-03-14 Xerox Corporation Method for two-color development of a xerographic charge pattern
JPS63265255A (ja) * 1987-04-23 1988-11-01 Canon Inc 多色画像形成装置
US5155541A (en) 1991-07-26 1992-10-13 Xerox Corporation Single pass digital printer with black, white and 2-color capability
WO2004088430A1 (fr) * 1991-10-16 2004-10-14 ＠ Support d'enregistrement d'informations electrostatique
JPH0635378A (ja) * 1992-07-21 1994-02-10 Konica Corp 画像形成装置
DE4408978C2 (de) 1993-03-17 1999-02-18 Hitachi Ltd Elektrophotographisches Verfahren und elektrophotographische Vorrichtung zur Bildererzeugung
JPH0844140A (ja) * 1994-08-04 1996-02-16 Fuji Xerox Co Ltd 多色画像形成方法及びその装置
US5600430A (en) * 1994-11-30 1997-02-04 Xerox Corporation Split recharge method and apparatus for color image formation

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US6205311B1 (en) 2001-03-20

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