Hewlett-packard Development Company, L.p.

Hp Indigo B.v.

Asaf Shoshani

Lavi Cohen

Meir Grinstein

Doron Schlumm

Ido Finkelman

Michael Vinokur

Michel Assenheimer

Shachar Berger

Alon Froom

Amit Porat

Yaniv Yona

Sharon Elbaz

Dorit Shalev

Naama Barak

Yulia Haddad

A printing drum for a liquid electrophotographic printing system which comprises a photosensitive surface and a heating device mounted to the printing drum. The heating device heats the photosensitive surface of the printing drum to a predetermined temperature.

Heating for a printing drum

A print apparatus is disclosed. In an example, the print apparatus comprises: a photoconductive surface to receive a latent image representative of an image to be printed onto a printable substrate; a plurality of print components, each print component having a surface movable relative to the photoconductive surface, wherein a current or voltage is to be applied between the print component surface and the photoconductive surface; and processing circuitry to: measure a current or voltage between each print component surface and the photoconductive surface; responsive to detecting a deviation in the measured current or voltage from a reference current or voltage in respect of any of the plurality of print components, determine that there exists a defect associated with the photoconductive surface; and determine, based on the amount of deviation of the measured current or voltage from the reference current or voltage, an indication of the size of the defect.

Determining the existence of defects in print apparatuses

A print apparatus is disclosed. The print apparatus includes a photoconductive surface to receive a latent image representative of an image to be printed onto a printable substrate; a charging component to apply a voltage is to be applied to the photoconductive surface as the charging component moves relative to the photoconductive surface; and processing circuitry to receive data indicative of a measurement of a first current resulting from the voltage applied by the charging component; determine, responsive to detecting an increase in the measured first current relative to a reference current, the increase being greater than a first defined threshold current, that there exists a point defect under affecting the latent image; and generate instruction data responsive to determining that there exists a point defect under affecting the latent image. A method and a machine-readable medium are also disclosed.

Determining the existence of point defects in print apparatuses

A liquid electro-photographic printing system, comprising: a binary ink developer assembly, a power supply arrangement, a switching arrangement, and a controller. The binary ink developer assembly includes a plurality of members defining a flow path for a printing fluid containing charged particles, the plurality of members including a first member and a second member that are arranged to generate an electric field therebetween, the first member having a plurality of segments. The power supply arrangement continuously provides a supply of voltages during a print operation, the voltages including a first voltage and a second voltage having a different voltage level from that of the first voltage. The switching arrangement switches the supply of voltages to the segments of the first member on an individual segment basis, to cause charged particles to be attracted to the first member in the individual segment when the first voltage is supplied to the individual segment and to cause charged particles to be repelled from the first member in the individual segment when the second voltage is supplied to the individual segment. The controller to determine timing of when to switch the supply of voltages to the segments.

Liquid electro-photographic printing transfer

A print apparatus component to be cleaned is rotated about a rotational axis. A cleaning element having a cleaning surface in contact with the print apparatus component is rotated. The cleaning element is oscillated in a direction parallel to the rotational axis. Rotation and oscillation of the cleaning element are varied according to a predetermined function to remove a residue from the print apparatus component.

Cleaning of print apparatus components with rotation and oscillation

A method of printing images in a liquid electrophotographic printer is provided. In an example, the method includes measuring at least one current associated with an image development unit of the liquid electrophotographic printer. A first time at which a peak occurs in the measured current is determined; the first time indicates that a printing substance is transferred from a point on a developer roller of the image development unit to a photo imaging member of the liquid electrophotographic printer at a first location within the image development unit. A second time at which said point on the developer roller is expected to contact the cleaner roller within the image development unit is calculated and, at the second time, a voltage applied to the cleaner roller is controlled to reduce the potential difference between the cleaner roller and the developer roller.

Voltage control in a liquid electrophotographic printer

A developer for a printer for printing to a substrate; the developer comprising a plurality of rollers operable to influence forming an image; the plurality of rollers comprising a developer roller for bearing printing liquid for forming the image and a squeegee roller for cooperating with the developer roller to influence the printing liquid on the developer roller, the squeegee roller being operable, via a brake, to stop rotating relative to the developer roller to influence the printing liquid on the developer roller.

Developers

In an example, charged particles suspended in a non-conductive fluid are fed to a transfer device. A width of a charged particles layer of uniform density on a surface of the transfer device is controlled. Charged particles are transferred from the charged particles layer to a photo imaging plate of a liquid electro-photographic printing system.

Liquid electro-photographic printing transfer devices

An example printing system for printing liquid ink has a developer device to transfer ink to an image plate of the printing system. The developer device has an ink inlet to receive ink from an ink reservoir of the printing system; a developer roller to transfer ink to the image plate, a motor to rotate the developer roller, and an ink sensor to detect arrival of ink at the developer device. The printing system is configured to start the motor in response to the ink sensor detecting arrival of ink at the developer device.

Detecting arrival of ink in a liquid ink printing system

In an example, a printing device comprises a component to engage with a surface, a first load sensor, a second load sensor and a controller. The component has a first part which is drivable to engage and disengage with the surface by a first engagement device and a second part which is drivable to engage and disengage with the surface by a second engagement device. The first load sensor is to measure a load on the first engagement device. The second load sensor is to measure a load on the second engagement device. The controller is to receive first load information from the first load sensor and second load information from the second load sensor; and determine whether or not to alter an operational parameter of the printing device, based on the received first load information and the received second load information.

Altering the operation of printing devices having engageable components

In one example, a development cycle of a binary ink developer, BID, is timed. Timing may be based on the length of a substrate in which the image is to be printed or the size of the image or the area to be printed with the ink associated to the BID.

Ink development

In an example, a method includes charging a photoconductive surface in a print apparatus and monitoring an electrical parameter associated with a proximity of a print apparatus component to the photoconductive surface. A relative spacing between the print apparatus component and the photoconductive surface may be changed and a contact between the print apparatus component and the photoconductive surface may be detected when the electrical parameter meets predetermined criteria.

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Ness Ziona, Israel

Asaf Shoshani