Hp Indigo B.v.

Hewlett-Packard Development Company, L.p.

Hewlett-Packard Indigo B.v.

Sasi Moalem

Kobi Shkuri

Reut Diamant

Eyal Shelef

Dmitry Maister

Seongsik Chang

Boaz Tagansky

Ran Waidman

Yossi Cohen

Shahar Tal

Shmuel Borenstain

Shlomo Harush

Gregory Braverman

Shaul Haim Raz

Gal Amit

Rafael Kahatabi

Dekel Green

Ronen Friedman

Moshe Issic

Amit Levi

Dror Kella

Michel Assenheimer

Fernanda Orlik

Amir Ofir

Peter Forgacs

Yohanan Sivan

Mirit Shitrit

Eviatar Golan

Ido Elad

In one example of the disclosure, a first sensor located adjacent to a first end of the blanket drum is utilized to take a first temperature reading. A second sensor located adjacent to a second end of the blanket drum is utilized to take a second temperature reading. A blanket creep condition is identified responsive to determining a difference in blanket drum temperatures is in excess of a predetermined threshold. A remedial measure is caused to be performed to address the blanket creep condition.

Identification and remedy of blanket creep conditions

A cleaning solution is used to at least substantially remove colorant from the photoconductive drum as the photoconductive drum rotates. A wiper wipes the cleaning solution from the photoconductive drum while purposefully maintaining a layer of the cleaning solution on the drum. The wiper has an edge that is purposefully rounded.

Maintaining layer of cleaning solution on photoconductive surface via wiper with purposefully rounded edge

In an example of a method for reducing contamination, a purified imaging oil is formed by filtering an imaging oil through an imaging oil filter, and then filtering the imaging oil through a polar absorbent filter. A surface of an amorphous silicon photoconductor of a liquid electrophotographic printing apparatus is maintained by periodically applying the purified imaging oil to the amorphous silicon photoconductor.

Method and apparatus for reducing contamination in liquid electrophotographic printing

A photoconductive layer in an image forming apparatus is refreshed. A first refreshing cycle is performed, including applying, at a first refresh unit, a first refresh voltage to the photoconductive layer and applying, at a second refresh unit, a second refresh voltage to the photoconductive layer. A second refreshing cycle is performed, including applying, at the first refresh unit, a third refresh voltage to the photoconductive layer, the third refresh voltage being higher than the first refresh voltage and higher than the second refresh voltage. Each of the first and second refreshing cycles electrically bias the photoconductive layer to a refresh polarity opposite to a print polarity applied during a print routine of the image forming apparatus.

Photoconductor refreshing cycles

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

An example method of determining dot gain in a liquid electrophotographic printer is described. The method involves effecting a print operation based on a predetermined digital dot area and measuring an operating current of a binary ink development unit during the print operation. A dot gain between the digital dot area and a physical dot area of a developed image is determined based on a function of the measured operating current.

Liquid electrophotographic dot gain determination

Examples of charging a photoconductive layer in an image forming apparatus are described. In one example, a method includes applying a charging voltage to the photoconductive layer and measuring surface voltages of the photoconductive layer at a plurality of positions on the photoconductive layer. Based on the measured surface voltages, a correction voltage profile is determined. The determined correction voltage profile includes at least a first correction voltage associated with a first position on the photoconductive layer and a second correction voltage associated with a second position, different to the first position, on the photoconductive layer. The method includes applying the first correction voltage to the photoconductive layer and applying the second correction voltage to the photoconductive layer.

Photoconductor charging uniformity correction

Examples of refreshing a photoconductive layer in an image forming apparatus are described. In one example, a method includes performing a first refreshing cycle comprising applying, at a first refresh unit, a first refresh voltage to the photoconductive layer and applying, at a second refresh unit, a second refresh voltage to the photoconductive layer. A second refreshing cycle is performed including applying, at the first refresh unit, a third refresh voltage to the photoconductive layer, the third refresh voltage being higher than the first refresh voltage and higher than the second refresh voltage. Each of the first and second refreshing cycles electrically bias the photoconductive layer to a refresh polarity opposite to a print polarity applied during a print routine of the image forming apparatus.

In an example implementation, a method of cleaning a silicon photoconductor includes contacting the silicon photoconductor with a base-peroxide solution, rinsing the silicon photoconductor with a liquid, and heating the silicon photoconductor to evaporate the liquid.

Cleaning a silicon photoconductor

A method is described in which a spectrum of a surface of a photoconductor member is obtained using optical spectroscopy; and an extent of oxidation of the surface is determined based on the obtained spectrum.

Determining oxidation of photoconductor members based on obtained spectrum from optical spectroscopy

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.

According to some examples, an apparatus includes a monitoring module to determine a length of a portion of an imaging member as the imaging member rotates; and indicate a fault condition in response to the determined length being different from a reference length.

Fault detection

An apparatus to calibrate a printer. The apparatus comprises a controller to: control deposition of white printing material on media, the white printing material having an opacity of at least 55%; control deposition of non-white printing material on the white printing material; receive data for at least one sensed characteristic of the non-white printing material; and calibrate the printer using the received data for the at least one sensed characteristic of the non-white printing material.

To calibrate a printer

In one example, an electrostatic printer includes: a photoconductor member; a charging unit to charge the photoconductor member to a charged voltage; an imaging unit to generate a latent electrostatic image on the photoconductor member by discharging areas of the charged photoconductor member; a developer unit to develop a toner image on the photoconductor member using a developer voltage; and a controller to change the developer voltage and to change the charged voltage dependent on the change of the developer voltage to keep the difference between the developer voltage and the charged voltage constant.

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Ness Ziona, Israel

Sasi Moalem