WO2022055487A1 - Électrode et changement de tension de développeur - Google Patents

Électrode et changement de tension de développeur Download PDF

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Publication number
WO2022055487A1
WO2022055487A1 PCT/US2020/050155 US2020050155W WO2022055487A1 WO 2022055487 A1 WO2022055487 A1 WO 2022055487A1 US 2020050155 W US2020050155 W US 2020050155W WO 2022055487 A1 WO2022055487 A1 WO 2022055487A1
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WO
WIPO (PCT)
Prior art keywords
optical density
developer
density change
cumulative
voltage
Prior art date
Application number
PCT/US2020/050155
Other languages
English (en)
Inventor
Ran Waidman
Nir GUTTMAN
Eyal NEGREANU
Original Assignee
Hewlett-Packard Development Company, L.P.
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 Hewlett-Packard Development Company, L.P. filed Critical Hewlett-Packard Development Company, L.P.
Priority to PCT/US2020/050155 priority Critical patent/WO2022055487A1/fr
Publication of WO2022055487A1 publication Critical patent/WO2022055487A1/fr

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G15/00—Apparatus for electrographic processes using a charge pattern
    • G03G15/06—Apparatus for electrographic processes using a charge pattern for developing
    • G03G15/10—Apparatus for electrographic processes using a charge pattern for developing using a liquid developer
    • G03G15/104—Preparing, mixing, transporting or dispensing developer
    • 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
    • G03G15/50—Machine control of apparatus for electrographic processes using a charge pattern, e.g. regulating differents parts of the machine, multimode copiers, microprocessor control
    • G03G15/5033—Machine control of apparatus for electrographic processes using a charge pattern, e.g. regulating differents parts of the machine, multimode copiers, microprocessor control by measuring the photoconductor characteristics, e.g. temperature, or the characteristics of an image on the photoconductor
    • 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
    • G03G15/50—Machine control of apparatus for electrographic processes using a charge pattern, e.g. regulating differents parts of the machine, multimode copiers, microprocessor control
    • G03G15/5062—Machine control of apparatus for electrographic processes using a charge pattern, e.g. regulating differents parts of the machine, multimode copiers, microprocessor control by measuring the characteristics of an image on the copy material

Definitions

  • a liquid toner electrophotography printer is configured to transfer a printing fluid, corresponding to the liquid toner, from a developer to a photo imaging plate (PIP). Due to characteristics of the printing fluid used, the transfer from the developer to the PIP takes place due to a voltage difference between the developer and the PIP. The quantity of printing fluid transferred from the developer to the PIP may be controlled by controlling the voltage difference, leading to optical density changes on images printed by the printer.
  • FIG. 1 illustrates an example method.
  • FIG. 2 illustrates another example method.
  • FIG. 3 illustrates yet another example method.
  • FIG. 4 illustrates a further example method.
  • FIG. 5 illustrates an example printer.
  • FIG. 6 illustrates another example printer.
  • optical density of an image printed by a printer is an element, among others, permitting assessing a printing quality. Each image is expected to be printed within some range of desired optical density.
  • Optical density may correspond to a proportion of light reflected from a printed surface. In some cases, a higher density corresponds to a higher proportion of light being absorbed by the printed surface or printed image, corresponding to a lower proportion of light being reflected by the same printed image or printed surface.
  • a lower density corresponds to a lower proportion of light being absorbed by the printed surface or printed image, corresponding to a higher proportion of light being reflected by the same printed image or printed surface.
  • Some image may be perceived as a high quality print when printed at a first optical density different while a different image may be perceived as a high quality print when printed at a second optical density different from the first.
  • Such relationship with quality and optical density may also vary from a printing substrate to another.
  • Optical density depends, on a liquid toner electrophotography printer, from a quantity of printing fluid deposed or transferred from a developer of the printer to a PIP of the printer.
  • a higher optical density corresponds to a higher quantity of printing fluid being transferred from the developer to the PIP.
  • the quantity of printing fluid transferred from the developer to the PIP is a function of the voltage difference between the PIP and the developer.
  • a higher voltage difference between the developer and the PIP corresponds to a higher amount of printing fluid being transferred from the developer to the PIP.
  • a higher voltage difference between the developer and the PIP would correspond to an increase in optical density.
  • a liquid toner electrophotography printer may be calibrated by changing voltage between its PIP and developer in order to change optical density. It was however realized that such voltage change may in turn have a number of consequences.
  • the voltage difference between the PIP and the developer is limited, for example to a maximum voltage difference value, or to a minimum voltage difference value. Such limitation may prevent or reduce the possibility to attain a desired optical density.
  • a relatively high voltage difference between the developer and the PIP may lead to transferring most or all of the printing fluid from the developer to the PIP, thereby potentially introducing different quality issues.
  • Such different quality issues may for example be linked to an external surface of the developer being irregular, such that a certain proportion of printing fluid should remain on the developer in order to even such developer surface irregularities.
  • Depleting a developer from printing fluid entirely may indeed introduce printing artefacts related to developer surface irregularities. It was found that undesired consequences such as these may be mitigated by proceeding with voltage changes either at the developer level or at an electrode level according to this disclosure.
  • the electrode is an element of a liquid toner electrophotography printer which is upstream of the developer as far as printing fluid flow is concerned. A developer is loaded with printing fluid from the electrode, the transfer of printing fluid from the electrode to the developer taking place in function of a voltage difference between the electrode and the developer.
  • the present disclosure relies on controlling optical density by either modifying the developer voltage, or by modifying the electrode voltage, the choice between modifying either the developer voltage or the electrode voltage taking into account the historical change of such voltages, aiming at minimizing the voltage change of each of the developer or the electrode.
  • changes of optical density have, over time, been obtained mostly from modifying the developer voltage
  • an upcoming voltage change will take place at the electrode level, to relieve the developer from voltage changes which could for example lead to reaching maximum or minimum developer voltage levels.
  • an upcoming optical density change may take place at the developer level to avoid or limit the possibility of having the electrode reaching a maximum or minimum electrode voltage limit. Proceeding in this manner permits spreading voltage changes over both the electrode and the developer in order to reach desired optical densities.
  • FIG. 1 illustrates an example method 100 for operating a liquid toner electrophotography printer according to this disclosure.
  • Liquid toner should in this disclosure be understood as a printing fluid, for example a printing fluid comprising pigments, for example polymer pigment resins milled to a particle size of for example 1 to 2 microns, a fuser oil, and a charging control fluid.
  • An electrophotography printer should in this disclosure be understood as a printer comprising a photographic imaging plate, a developer and an electrode.
  • the photographic imaging plate has in some examples a cylinder shape.
  • the photoconductive surface may be selectively charged with a latent electrostatic image having image and background areas with different potentials.
  • an electrostatic ink composition comprising charged toner particles, which may be suspended in a liquid carrier, can be brought into contact with the selectively charged photoconductive surface by the developer.
  • the charged toner particles adhere to the image areas of the latent image while the background areas remain clean.
  • the image is then transferred to a print medium (e.g. paper) directly or, in some examples, by being first transferred to an intermediate transfer member, which can be a soft swelling blanket, and then to the print medium.
  • An electrode according to this disclosure should be understood as any electrode suitable for applying a voltage between the electrode and the developer.
  • the electrode may be stationary relative to the developer.
  • the electrode may have a shape that, at least in part, corresponds to the shape of at least part of the developer.
  • the electrode may have a cross section that forms part of a circle, the center of this circle being the same as that for the cylinder of the developer.
  • the electrode may have an inner surface that forms part of a cylinder shape, the axis of this cylinder shape being the same as that for the cylinder of the developer.
  • the electrode may form a wall or part of a wall of a reservoir for the printing fluid.
  • an additional electrode may be present that is at substantially the same or at the same potential as the electrode, the additional electrode located adjacent the electrode and the developer.
  • the electrode and an additional electrode may together form walls or parts of walls of a reservoir for the printing fluid.
  • there is a gap between the developer and the electrode is of more than 100 pm, in some examples of more than 200 pm, in some examples of more than 300 pm.
  • the gap between the electrode and the developer is from 100 pm to 1000 pm, in some examples from 100 pm to 800 pm, in some examples from 100 pm to 700 pm, in some examples from 200 pm to 600 pm, in some examples from 200 pm to 600 pm, in some examples from 300 pm to 500 pm, in some examples from 350 pm to 450 pm.
  • the electrode may be in the form of or a belt, having a surface that can move in the same direction as the surface of the developer, and may contact the surface of the developer. If the electrode is in the form of a, e.g. a cylinder, the roller of the electrode may have a diameter that is less than the diameter of developer.
  • the electrode may comprise any electrically conducting material, including, but not limited to, a metal and carbon.
  • the electrode may comprise a metal selected from copper, aluminum, and steel.
  • a voltage or potential is applied between the developer and the electrode such that the printing fluid, for example comprising resin particles, is charged and adhere to the developer.
  • the potential or voltage difference between the developer and the electrode may be of more than 1200 V, in some examples of more than 1300 V, in some examples of more than 1350 V or more, in some examples of more than 1400 V, in some examples of more than 1500 V, in some examples of more than 1800 V, in some examples of more than 2000 V, in some examples of more than 2400 V.
  • the voltage applied to the electrode is - 1800 V or less (i.e.
  • the developer is at a potential or voltage more positive than the electrode.
  • the developer may, for example, be at a potential of -600 V or more, in some examples -550 V or more, in some examples -500 V or more, in some examples -450 V or more, in some examples -400 V or more.
  • the potential applied to the electrode is 1800 V or more (i.e. more positive), in some examples 2000 V or more, in some examples 2200 V or more, in some examples 2200 V or more, in some examples 2500 V or more, and the developer is at a potential less positive than the electrode.
  • the developer may, for example, be at a potential of 600 V or less, in some examples 550 V or less, in some exanlples 500 V or less, in some examples 450 V or less, in some examples 400 V or less.
  • An external surface of the developer may travel at a speed of from 0.1 to 5 m/sec, in some examples 0.5 to 4 m/sec, in some examples 1 to 3 m/sec, in some examples 1.5 to 2.5 m/sec, in some examples about 3 m/sec.
  • the gradient of the potential in the gap between the developer and the electrode may be in some examples of more than IxlO 5 V/m, in some examples of more than 5xl0 5 V/m, in some examples more than IxlO 6 V/m, in some examples of more than 2xl0 6 V/m, in some examples of more than 3xl0 6 V/m, in some examples of more than 4xl0 6 V/m, in some examples of more than 5xl0 6 V/m, in some examples of more than 5.5xl0 6 V/m, in some examples of more than 6xl0 6 V/m.
  • the gradient of the potential in the gap between the developer and the electrode may be from IxlO 5 V/m to IxlO 8 V/m, in some examples from IxlO 5 V/m to IxlO 7 V/m, in some examples from IxlO 6 V/m to 1 xlO 7 V/m, in some examples from 2xl0 6 V/m to 8x1 0 6 V/m, in some examples from 2xl0 6 V/m to 7x1 0 6 V/m, in some examples from 2xl0 6 V/m to 7xl0 6 V/m, in some examples from 3xl0 6 V/m to 6xl0 6 V/m.
  • the gradient potential may be calculated by determining the difference in voltage between the developer and the electrode, and dividing this difference in potential by the distance of the gap between the developer and the electrode at their closest point.
  • the first electrode may be positioned below the developer, with a separation between the electrode and developer forming a gap.
  • the method may be such that the printing fluid for the electrostatic printing process fills, or at least partially fills, the gap between the developer and the electrode, and the voltage is applied such that the printing fluid becomes adhered to the developer.
  • the electrode comprises a roller, which is positioned below the developer, and in a reservoir for the printing fluid.
  • a developer according to this disclosure may comprise a metal.
  • the developer is a developer roller comprising a metal and having a surface covering comprising an elastomeric material.
  • the developer may comprise a metal core with an outer surface layer comprising an elastomeric material.
  • the metal may be selected from, but is not limited to, steel, aluminum and copper.
  • the surface covering or outer surface layer may comprise an elastomeric material and a resistivity control agent, which may be dispersed in the elastomeric material.
  • the resistivity control agent may act to increase or decrease the resistivity of the elastomeric material (compared to the same material absent said resistivity control agent).
  • the elastomeric material may comprise a material selected from chloroprene rubber, isoprene rubber, EPDM rubber, polyurethane rubber, epoxy rubber, butyl rubber, fluoroelastomers (such as the commercially available Viton) and polyurethane.
  • the resistivity control agent which may be dispersed in the elastomeric material, may be selected from an ionic material, a metal, or carbon.
  • the ionic material may be a quaternary ammonium compound.
  • the resistivity control agent which may be dispersed in the elastomeric material, may be selected from organic dyes, organic pigments, organic salts, polyelectrolytes, inorganic salts, plasticisers, inorganic pigments, metallic particles, charge transfer complexes or materials which produce charge transfer complexes with the elastomeric material, e.g. polyurethane.
  • the resistivity control agent may be present in an amount of 0.1 to 6 % by weight of the surface covering, with, in some examples, the remaining weight percentage being the elastomeric material.
  • the resistivity control agent may be or may comprise a quaternary ammonium compound. In some examples, the resistivity control agent is a lithium salt.
  • the resistivity of the surface of the developer roller may be from 1 * 10 5 Ohm x m to 1 * 10 8 Ohm x m, in some examples 1 * 10 6 Ohm x m to I x lO 7 Ohm x m.
  • Method 100 comprises, in block 101, monitoring an optical density of images printed by the printer.
  • the monitoring should be understood as an in line monitoring, whereby the optical density of images is monitored as they have been printed.
  • the monitoring may take place using an optical density sensor, for example an optical densitometer or a spectrophotometer.
  • the printer comprises the optical density sensor.
  • the optical density sensor is connected to a printer controller of the printer and is configured to transmit optical density data to the printer controller.
  • the optical density sensor is located downstream from a media path of the printer, the optical sensor scanning the printed media. Such monitoring permits evaluating a quality of the printed images by evaluating whether the effective measured optical density corresponds to a desired optical density.
  • Method 100 comprises, in block 102, storing a first cumulative optical density change value, the first cumulative optical density change value being induced by developer voltage changes.
  • the first cumulative optical density change value should be understood as cumulating optical density value changes induces by developer changes, as per optical density data obtained at block 101. In other words, if developer voltage is changed in order to change optical density, such change in optical density is added to the first cumulative optical density change value. If, over time, the developer voltage is changed to progressively raise the optical density change value, the first cumulative optical density change will also progressively raise, reflecting the change in optical density.
  • the first cumulative optical density change should be understood as exclusively taking developer voltage changes into account.
  • a change in optical density which would not be due to a change in developer voltage should not be added (or subtracted) to the first cumulative optical density change value.
  • the first cumulative optical density change value takes positive or negative optical density changes into account.
  • a positive optical density change meaning that the optical density increases
  • Introducing the first cumulative optical density change value permits evaluating a contribution of developer voltage change to optical density changes.
  • the storing may take by at a data storage or memory of a printer controller.
  • Method 100 comprises, in block 103, storing a second cumulative optical density change value, the second cumulative optical density change value being induced by electrode voltage changes.
  • the second cumulative optical density change value should be understood as cumulating optical density value changes induces by electrode changes, as per optical density data obtained at block 101. In other words, if electrode voltage is changed in order to change optical density, such change in optical density is added to the second cumulative optical density change value. If, over time, the electrode voltage is changed to progressively raise the optical density change value, the second cumulative optical density change will also progressively raise, reflecting the change in optical density.
  • the second cumulative optical density change should be understood as exclusively taking electrode voltage changes into account.
  • a change in optical density which would not be due to a change in electrode voltage should not be added (or subtracted) to the second cumulative optical density change value.
  • the second cumulative optical density change value takes positive or negative optical density changes into account.
  • a positive optical density change meaning that the optical density increases
  • Introducing the second cumulative optical density change value permits evaluating a contribution of electrode voltage change to optical density changes.
  • the storing may take by at a data storage or memory of a printer controller.
  • Method 100 comprises, in block 104, detecting that the monitored optical density deviates from an operational optical density profile.
  • An operational optical density profile may correspond to an optical density range, or be defined by an operation optical density threshold, above which the optical density may pass, in some examples of such threshold defining a maximum desired optical density, or below which the optical density may fall, in some examples of such threshold defining a minimum optical density threshold.
  • the detecting that the monitored optical density deviates from an operational optical density profile as described for example in block 104 comprises comparing the monitored optical density to an operational optical density threshold, the monitored optical density falling below or above the operational optical density threshold.
  • the operational density profile may be image dependent or printing media dependent, or both.
  • the operational density profile may comprise different levels, such levels corresponding in some cases to different levels of voltage changes, such that a significant optical density deviation may be corrected by a significant voltage change. Detecting that the monitored optical density deviates from an operational optical density profile permits detecting that a quality issue linked to optical density is taking place, and will enable correcting, at least partially, such quality issue as per the present disclosure.
  • Method 100 comprises, in block 105, comparing the first cumulative stored cumulative optical density change value to the second cumulative optical density change value in response to detecting that the monitored optical density deviates from the operational optical density profile.
  • Such comparison permits evaluating whether the optical density change value has been mostly changed, overall in a same direction, by changing developer voltage, or whether the optical density change value has been mostly changed, overall in a same direction, by changing electrode voltage.
  • the optical density is progressively raised over time. In such a case, if optical density is raised by raising developer voltage mostly or exclusively, such developer may be depleted from printing fluid or reach a maximum voltage limit.
  • the comparing according to block 105 permits evaluating a contribution of developer voltage changes compared to electrode voltage changes in order to reduce or altogether prevent that such issues.
  • Method 100 comprises, in block 106, changing either a developer voltage or an electrode voltage to maintain an optical density change differential between the first cumulative optical density change value and the second cumulative optical density change value within an operational optical density change differential profile in response to detecting that the monitored optical density deviates from the operational optical density profile.
  • a selective change of either the developer voltage or of the electrode voltage is aimed at avoiding that voltage change may be overly carried on by either one of the developer or the electrode, permitting spreading such changes to maintain the optical density change differential within the operational optical density change differential profile.
  • the optical density change differential may for example be a difference between the first cumulative optical density change value and the second cumulative optical density change value.
  • different weights are assigned to the first cumulative optical density change value and to the second cumulative optical density change value to obtain the optical density change differential, for example to take into account the respective criticality or flexibility of voltage change of either the developer or the electrode.
  • a relatively high optical density change differential would imply that one of the developer element or electrode element has been submitted to voltage change leading to a more significant optical density change than the other element.
  • a relatively low optical density change differential would imply that both of the electrode and the developer share the voltage changes leading to optical density changes.
  • the operational optical density change differential profile corresponds to acceptable optical density change differentials. In some cases, the operational optical density change differential profile corresponds to an optical density change differential range.
  • the operational optical density change differential profile corresponds to an operational optical density change differential threshold below which the optical density change differential is maintained.
  • the changing either a developer voltage or an electrode voltage to maintain an optical density change differential between the first cumulative optical density change value and the second cumulative optical density change value within an operational optical density change differential profile comprises maintaining the optical density change differential below an optical density change differential threshold.
  • the changing either a developer voltage or an electrode voltage to maintain an optical density change differential between the first cumulative optical density change value and the second cumulative optical density change value within an operational optical density change differential profile comprises changing the developer voltage when the first cumulative optical density change value is lower than the second cumulative optical density change value, and changing the electrode voltage when the first cumulative optical density change value is higher than the second cumulative optical density change value.
  • both the developer and the electrode contribute, alternatively, to the change of optical density, maintaining the optical density change differential at a particularly reduced level over time, thereby preventing or reducing the risk of either the developer element or the electrode element from reaching a minimal or maximum voltage level which would prevent further optical change from the element concerned.
  • FIG. 2 illustrates an example method 200 according to this disclosure.
  • Method 200 comprises blocks 101-106 as described in the context of example method 100.
  • Method 200 further comprises, in block 207, proceeding with a color calibration of the printer.
  • a color calibration should be understood as a calibration procedure involving the printing of a specific calibration image.
  • a color calibration of the printer comprises depositing, by one or more printing elements, a printing fluid, for example colored inks, onto a first substrate according to respective output settings.
  • the respective output settings for any given color may initially be the same regardless of the location on the substrate where the color is to be printed.
  • An initial “test” image is printed. This test image may be the desired image to be printed, or it may be an abstracted version of the desired image.
  • the abstracted version may include patches of colors printed at a plurality of locations, where a patch of color corresponds to a color located at that particular location within the image.
  • a color calibration should be understood as resulting in setting the different voltages of components of the printer, in particular the electrode and developer voltages. Such a color calibration may take place periodically, and permit resting or adjusting system parameters of the printer.
  • Method 200 further comprises, in block 208, resetting the first cumulative optical density change value and the second cumulative optical density change value in response to the proceeding with the color calibration.
  • the color calibration corresponds to a reset of a method according to this disclosure, an example method according to this disclosure permitting for example voltage adjustment between successive color calibrations.
  • Other resetting of the first cumulative optical density change value and the second cumulative optical density change value may take place in other situations, for example following replacement of a component of the printer such as the PIP.
  • block 207 is as a result of either one of the developer voltage or electrode voltage reaching a respective developer voltage limit or electrode voltage limit, the color calibration permitting resting parameters of the printer permitting a positioning of the various voltages in line with operational parameters.
  • a printer such as the printer to which example methods hereby described may be applied, comprises a plurality of developers and a plurality of respective electrodes, the method being followed for each developer and respective electrode, the optical density change differential being specific to each developer and respective electrode.
  • Such printer may for example permit printing using different printing fluids, for example printing fluids corresponding to different colors.
  • the PIP may be a single PIP, each of the developers transferring a respective printing fluid onto the PIP.
  • the examples hereby described may be specific to specific electrode - developer pairs for example due to the fact that some printing fluids or some developers imply different constraints as to maintaining a minimum amount of printing fluid on the respective developer.
  • Method 300 comprises blocks 101-106 as described in the context of example method 100. While not represented, method 300 could also comprise blocks 207 and 208 in some alternative examples. Method 300 further comprises, in block 309, transferring liquid toner from a developer to the photo imaging plate, whereby the transferred liquid toner is of less than 90% by weight of an original liquid toner amount present on a surface of the developer prior to the transferring. Proceeding in this manner permits ensuring that some liquid toner remains on the developer. Such liquid toner remaining on the developer may be called PID or partial ink development, and corresponds to an excess quantity of liquid toner permitting for example to reduce or supress the effect of developer surface irregularities.
  • the transferred liquid toner is of less than 85% by weight of an original liquid toner amount present on a surface of the developer prior to the transferring. In some examples, the transferred liquid toner is of less than 80% by weight of an original liquid toner amount present on a surface of the developer prior to the transferring. In some examples, the transferred liquid toner is of less than 75% by weight of an original liquid toner amount present on a surface of the developer prior to the transferring. In some examples, the transferred liquid toner is of less than 70% by weight of an original liquid toner amount present on a surface of the developer prior to the transferring. In some examples whereby the printer comprises a plurality of developers and a plurality of respective electrodes, each electrode and developer pair may correspond to a specific percentage of transferred liquid as per block 309, such percentage being adapted to the developer, electrode and printing fluid concerned.
  • the first cumulative optical density change value and the second cumulative optical density change value change monotonically over time.
  • a developer voltage would be more likely to reach some maximum or minimum voltage limit, in which case the example methods hereby described would result particularly beneficial.
  • Method 400 comprises blocks 101-106 as described in the context of example method 100. While not represented, method 400 could also comprise blocks 207 and 208 in some alternative examples. While not represented, method 400 could also comprise block 309 in some alternative examples. Method 400 further comprises, in block 410, maintaining a thickness of liquid toner on a surface of the developer above a minimum liquid toner thickness threshold. The thickness of liquid toner may for example be measured on the developer between a squeegee roller and an area of contact between the developer and the PIP, downstream from the electrode. In some examples, a thickness of liquid toner on a surface of the developer is above a minimum liquid toner thickness threshold of 0.25 micron.
  • a thickness of liquid toner on a surface of the developer is above a minimum liquid toner thickness threshold of 0.5 micron. In some examples, a thickness of liquid toner on a surface of the developer is above a minimum liquid toner thickness threshold of 0.7 micron. In some examples, a thickness of liquid toner on a surface of the developer is above a minimum liquid toner thickness threshold of 0.9 micron. In some examples, a total thickness of liquid toner on the surface of the developer comprises both the minimum liquid toner thickness permitting maintaining the PID on a surface of the developer and a thickness of liquid toner which will be transferred to the PIP, whereby such total thickness is below a maximum liquid toner thickness threshold.
  • such total thickness is below a maximum liquid toner thickness threshold of 6 micron. In some examples, such total thickness is below a maximum liquid toner thickness threshold of 5.5 micron. In some examples, such total thickness is below a maximum liquid toner thickness threshold of 5 micron. In some examples, such total thickness is below a maximum liquid toner thickness threshold of 4.5 micron. In some examples, about 4 micron thickness of liquid toner is transferred from the developer to the PIP, about 1 micron of liquid toner remaining on the surface of the developer as PID, the liquid toner transferred from the developer to the PIP (corresponding to the about 4 micron) leading to a thickness of about a micron of toner when dried.
  • FIG. 5 illustrates an example liquid toner electrophotography printer 500 configured to operate according to any of the example methods hereby described, the printer comprising a photo imaging plate 501, a developer 502, an electrode 503, an optical sensor 504 and a printer controller 505.
  • the printer controller 505 comprises a processor 506 and a storage 507 coupled to the processor 506, the printer controller further comprising an instruction set 508.
  • the instruction set 508 is to cooperate with the processor 506 and the storage 507 to: operate the optical sensor 504 to measure an optical density of images printed by the printer 500 over time; collect, in the storage 507, a first cumulative optical density change value resulting of a developer voltage change; collect, in the storage 507, a second cumulative optical density change value resulting of an electrode voltage change; compare, by the processor 506, the measured optical density to an operational optical density profile, compare, by the processor 506, the first cumulative optical density change value and the second cumulative optical density change value; modify a developer voltage when both the measured optical density differs from the operational optical density profile and modifying the developer voltage would reduce an optical density change differential between the first cumulative optical density change value and the second cumulative optical density change value; and modify an electrode voltage when both the measured optical density differs from the operational optical density profile, and the modifying the electrode voltage would reduce an optical density change differential between the first cumulative optical density change value and the second cumulative optical density change value.
  • printer 500 permits evaluating the optical density of images printed by printer 500 using the optical sensor 504, which may for example be a spectrophotometer or an optical densitometer, thereby permitting detecting if the measured optical density differs from the operational optical density profile in order to take action either on the developer voltage or on the electrode voltage as per the present disclosure.
  • the developer voltage is modified when the optical density is not as desired, i.e. differing from the operational optical density profile, and if the modification of the developer voltage would reduce the optical density change differential.
  • Processor 506 may comprise electronic circuits for computation managed by an operating system.
  • the first cumulative optical density change has a value of FCODC1
  • the second cumulative optical density change has a value of SCODC1
  • the objective her is to maintain the first cumulative optical density change and the second cumulative optical density change close to each other to avoid reaching extreme values in one sense or another.
  • the first cumulative optical density change has a value of FCODC3
  • the second cumulative optical density change has a value of SCODC3
  • FIG. 6 illustrates an example printer 600.
  • Example printer 600 comprises components 501-508 as described in the context of printer 500.
  • Example printer 600 further comprises 6 additional developers 622-627 and 6 additional electrodes 632-637.
  • Printer 600 comprises a plurality of developers 502, 622-627 and respective electrodes 503, 632-637, the plurality of developers and respective electrodes being configured to transfer printing fluid on the photo imaging plate 501, whereby the instruction set 508 is to cooperate with the processor 506 and the storage 507 to maintain a minimum amount of liquid toner on each developer 502, 622-627. This permits maintaining a PID on each developer.
  • While the represented printer 600 comprises a total of 7 developers, other numbers of developers may be used in other examples, such as 2 developers, 3 developers, 4 developers, 5 developers, 6 developers, or more than 7 developers.
  • Each developer may be associated to a respective electrode, and to a respective printing fluid.
  • Each developer-electrode-printing fluid association may be operated according to the examples method hereby described independently from other developer-electrode-printing fluid associations in the same printer, thereby permitting taking into account specificities of each developer-electrode-printing fluid association such as a specific PID for example.
  • Figures 5 and 6 also illustrate an example non transitory readable storage medium such as storage 507 encoded with instructions 508 executable by processor 506, the machine readable storage medium 507 comprising: instructions 508 to compare the effect of a developer voltage change and of an electrode voltage change in an optical density of images printed by a liquid toner electrophotography printer over time; instructions to modify either a developer voltage or an electrode voltage in order to both maintain the optical density of the images printed by the printer within an optical density profile, and maintain an optical density change differential between a cumulative optical density change value induced by developer voltage changes and a cumulative optical density change value induced by electrode voltage changes within an operational optical density change differential profile.
  • the effect of a developer voltage change and of an electrode voltage change may be to raise or lower an optical density of the printer.
  • raising developer voltage may raise optical density.
  • raising developer voltage may reduce optical density.
  • raising electrode voltage may raise optical density.
  • raising electrode voltage may reduce optical density.
  • reducing developer voltage may raise optical density.
  • reducing developer voltage may reduce optical density.
  • reducing electrode voltage may raise optical density.
  • reducing electrode voltage may reduce optical density.
  • Such different configurations may depend on levels of voltage used in the printer concerned. While each printer has a relationship linking voltage levels to optical density levels, such relationship may vary from printer to printer in function of the configuration of a given printer.
  • the example non transitory readable storage medium such as storage 507 permits operating any of the example printers hereby described according to any example method hereby described.
  • a computer readable storage or non transitory readable storage medium may be any electronic, magnetic, optical or other physical storage device that stores executable instructions.
  • the computer readable storage may be, for example, Random Access Memory (RAM), an Electrically Erasable Programmable Read Only Memory (EEPROM), a storage drive, and optical disk, and the like.
  • RAM Random Access Memory
  • EEPROM Electrically Erasable Programmable Read Only Memory
  • Storage or memory may include any electronic, magnetic, optical or other physical storage device that stores executable instructions as described hereby.
  • the instructions 508 to modify either the developer voltage or the electrode voltage comprise instructions to increase or decrease either the developer voltage or the electrode voltage in order to increase or, respectively, decrease, the optical density of the images printed. Indeed, in some specific examples, the change takes place in a specific change direction, for example due to specific printer characteristics. In such situations, it is possible that a progressive optical density drifting of the printer may lead the voltage of either of the electrode or developer to reach a minimum or maximum voltage admitted by the printer.
  • the machine readable storage medium comprises instructions 508 to trigger a color calibration when either one of the developer voltage or electrode voltage has reached a respective maximum or minimum voltage threshold. In such cases, such color calibration may permit resetting printer parameters to set voltage levels at acceptable levels, resetting the first cumulative optical density change value and the second cumulative optical density change value to start operating the printer according to example methods hereby described.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Wet Developing In Electrophotography (AREA)

Abstract

Des exemples comprennent un procédé permettant de faire fonctionner une imprimante électrophotographique à toner liquide. Le procédé consiste à surveiller une densité optique d'images imprimées par l'imprimante, à stocker une première valeur de changement de densité optique cumulative induite par des changements de tension de développeur, et à stocker une seconde valeur de changement de densité optique cumulative induite par des changements de tension d'électrode. Le procédé consiste également à détecter que la densité optique surveillée s'écarte d'un profil de densité optique opérationnel. Le procédé consiste également, en réponse à l'écart de la densité optique surveillée, à comparer la première valeur de changement de densité optique cumulative stockée à la seconde valeur de changement de densité optique cumulative ; et à changer une tension de développeur ou une tension d'électrode pour maintenir un différentiel de changement de densité optique entre la première valeur de changement de densité optique cumulative et la seconde valeur de changement de densité optique cumulative dans un profil différentiel de changement de densité optique opérationnel.
PCT/US2020/050155 2020-09-10 2020-09-10 Électrode et changement de tension de développeur WO2022055487A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2017146434A (ja) * 2016-02-17 2017-08-24 富士ゼロックス株式会社 キャリア液除去制御装置、画像形成装置
WO2018192658A1 (fr) * 2017-04-20 2018-10-25 Hp Indigo B.V. Feuilles de nettoyage imprimées
US20190146375A1 (en) * 2015-07-28 2019-05-16 Hp Indigo B.V. Electrophotographic printers
US20190286015A1 (en) * 2015-08-19 2019-09-19 Hp Indigo B.V. Controlling ink developer voltages
WO2019190509A1 (fr) * 2018-03-28 2019-10-03 Hewlett-Packard Development Company, L.P. Commande de profils de tension
WO2019212477A1 (fr) * 2018-04-30 2019-11-07 Hewlett-Packard Development Company, L.P. Réglage de densité optique

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20190146375A1 (en) * 2015-07-28 2019-05-16 Hp Indigo B.V. Electrophotographic printers
US20190286015A1 (en) * 2015-08-19 2019-09-19 Hp Indigo B.V. Controlling ink developer voltages
JP2017146434A (ja) * 2016-02-17 2017-08-24 富士ゼロックス株式会社 キャリア液除去制御装置、画像形成装置
WO2018192658A1 (fr) * 2017-04-20 2018-10-25 Hp Indigo B.V. Feuilles de nettoyage imprimées
WO2019190509A1 (fr) * 2018-03-28 2019-10-03 Hewlett-Packard Development Company, L.P. Commande de profils de tension
WO2019212477A1 (fr) * 2018-04-30 2019-11-07 Hewlett-Packard Development Company, L.P. Réglage de densité optique

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