Hp Indigo B.v.

Hewlett-Packard Development Company, L.p.

Hewlett-Packard Indigo B.v.

Shmuel Borenstain

Asaf Anufa

Doron Schlumm

Uri Lidai

Henryk Birecki

Seongsik Chang

Gil Bar-Haim

Sasi Moalem

Shahar Stein

Gregory Katz

Shachar Berger

Regina Guslitzer

Maty Verner

Ami Halfon

Amit Levi

Ronen Friedman

Moshe Issic

Ronen Bitan

David Meshulam

Dror Kella

Michael Kokotov

Yavin Atzmon

Eyal Negreanu

Amir Kedem

Ziv Seemann

Roy Har-Tsvi

Sagi Daren

Yonni Hartstein

Alexander Yekymov

Yinon Harari

Keren Goldshtein

David Savelzon

Yonatan Gamzon-Kapeller

An example printing fluid apparatus, for a printing system, comprises a printing fluid reservoir to store printing fluid for use in a print job and a printing fluid channel to route printing fluid from the reservoir to the reservoir and to route printing fluid from a printing station of the printing system to the reservoir. The fluid channel comprises a port to introduce printing fluid from a printing fluid cartridge into the fluid channel such that the introduced printing fluid from the printing fluid cartridge at least partially mixes with printing fluid in the fluid channel.

Mixing printing fluid

A method of calibrating a developer unit of a liquid electrophotographic printer, the method comprising: setting a developer roller voltage and iteratively printing a patch on a print medium using different electrode voltages until a hue of a patch printed using one of the electrode voltages is within a tolerance of a target hue; and setting an electrode voltage based on said one of the electrode voltages and iteratively printing a patch on a print medium using different developer roller voltages until a hue of a patch printed using one of the developer roller voltages is within the tolerance of the target hue.

Hue based color calibration

In one aspect an apparatus for use in an electrographic printer is described. The apparatus includes a housing defining a cavity, a developer roller, a developer electrode for developing printing substance onto the developer roller, the electrode being arranged within the cavity, and a heater for heating printing substance to be developed onto the developer roller, the heater being arranged in the cavity.

Apparatus for use in an electrographic printer

During a print cycle of a print apparatus, a liquid print agent including a carrier fluid is applied to a photoconductive surface. A proportion of the carrier fluid in the liquid print agent on the photoconductive surface is reduced at a first location by removably collecting a portion of the carrier fluid from the liquid print agent applied to the photoconductive surface. During a non-print cycle of the print apparatus, the removably collected portion of the carrier fluid is added to the photoconductive surface at the first location.

Carrier fluid addition during non-print cycles

In one aspect an apparatus () for use in an electrographic printer () is described. The apparatus includes a housing () defining a cavity (), a developer roller (), a developer electrode () for developing printing substance onto the developer roller, the electrode being arranged within the cavity, and a heater () for heating printing substance to be developed onto the developer roller, the heater being arranged in the cavity.

An example method of performing a null cycle in a liquid electrographic printer is described. The method involves collecting, at a photo imaging plate cleaning station, imaging oil deposited on a photo imaging plate during a print cycle. During a null cycle, the photo imaging plate cleaning station is controlled to apply the collected imaging oil to the photo imaging plate.

Operating a liquid electrophotographic printer

In an example of a printing system, the amount of a printing fluid that is transferred from a developer unit onto an imaging plate is varied in order to alter the optical density of an area covered by the printing fluid.

Printing by printing fluid transfer

In an example, a first wiper blade is to contact the photoconductive surface and to wipe at least some of particles and fluid from the photoconductive surface and wherein a second wiper blade is to contact the photoconductive surface and to wipe at least some of the particles and fluid that have passed the first wiper blade, from the photoconductive surface. The first wiper blade includes at least one perforation forming a passage through the wiper blade to transmit part of the particles and fluid during wiping.

System for wiping a photoconductive surface

In certain examples, a liquid electrophotographic printer has a charge erasing element and a charging element. The charge erasing element at least partially discharges a charged photo imaging plate and a charged layer of liquid toner and the charging element at least partially recharges the layer of liquid toner and the photo imaging plate.

Charging elements in electrophotographic printers

In an example, a method includes applying a liquid print agent comprising a carrier fluid to a photoconductive surface and reducing a proportion of the carrier fluid in the liquid print agent on the photoconductive surface at a first location during a print cycle of a print apparatus. The method may further include, during a non-print cycle of the print apparatus, adding carrier fluid to the photoconductive surface at the first location.

In one example, a method is described that includes a processor detecting a voltage of a photoconductor layer of a printing device, comparing the voltage of the photoconductor layer to a threshold voltage, and applying a corrective voltage to a charging unit or to a transfer member when the voltage of the photoconductor layer exceeds the threshold voltage.

Applying a corrective voltage

A method of electrostatic printing may include forming a latent electrostatic image on a surface and transferring a first volume of a charged toner to the latent electrostatic image on the surface. The method may also include transferring a second volume of a charged toner to the surface, such that a toner image including the first volume of charged toner and the second volume of charged toner is formed on the surface, the second volume of charged toner being disposed on the first volume of charged toner. The method may also include transferring the image to a print substrate.

Electrostatic printing

In certain examples, a liquid electrophotographic printer has a compressive element. The compressive element removes a portion of carrier liquid from an inked image on an imaging element. The compressive element is selectively engageable and a controller disengages the compressive element for a first layer of liquid toner so as to retain carrier liquid in the first layer, and engages the compressive element for a subsequent layer of liquid toner so as to remove a portion of carrier liquid from the subsequent layer.

Liquid electrophotographic printers

In one example, a method for calibrating a position of a charge roller is described. The method may include a processor positioning a first end of a charge roller to a first plurality of index positions, determining a capacitance between the charge roller and a photoconductor imaging plate at each of the first plurality of index positions, determining a first index position of the first plurality of index positions with a greatest change in capacitance, and calibrating a position of the charge roller based upon the first index position.

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Ness Ziona, Israel

Shmuel Borenstain