Hp Indigo B.v.

Yuval Yunger

Haim Vladomirski

Oron Ambar

Craig Breen

Guy Nesher

Tal Frank

Benny Kimelman

Tsahi Geller

In an example, a method includes determining an indication of pixel separation for an image region to be printed to a substrate. A power level of a laser light source to address a pixel on a region of a photoconductive surface corresponding to the image region may be adjusted based on the indication of pixel separation to compensate for print spot size variation associated with pixel separation.

Adjusting power levels to compensate for print spot size variation

A method of controlling a laser unit in order to negate heat build-up caused by a laser modulation current, and eliminating artifacts caused by image related thermal effects. Upon receipt of an activation signal, an activation current is applied which causes lasing of the laser unit. Upon receipt of a deactivation signal, the method ceases lasing by selectively applying either an idle current below the activation current, or a cooling current below the idle current.

Laser units

Certain examples described herein relate to an optical controller () for an exposure unit () of a printer. In certain examples, memory () stores a plurality of data structures each comprising adjustment factors useable to adjust a plurality of optical elements () of the exposure unit. Different data structures correspond to different gray coverages in an image generated by the printer. In certain examples, a processor () determines gray levels for different image regions in input image data. In certain cases, the processor links the determined gray levels to corresponding data structures within the plurality of data structures to obtain adjustment factors for the different image regions. In certain cases, the processor adjusts the optical elements for each image region using the corresponding obtained adjustment factors to enable the generation of an exposed image using the exposure unit based on the input image data.

Generating an exposed image

An electric cross-talk, ECT, effect of laser-diode array is measured by capturing a first image of a first laser spot of a first laser diode with a second laser diode being turned off () and a second image of a second laser spot of the first laser diode while switching on the second laser diode (). A spot-energy ratio is determined () by processing the images, and an ECT-coupling coefficient on the first laser diode is calculated () by switching the second laser diode. Compensating for the ECT effect includes determining a signal for predicting the ECT effect on the first laser diode by switching the second laser diode, and generating a driving signal based on a desired current profile and the ECT-prediction signal.

Growing community of inventors

Ness Ziona, Israel

Yuval Yunger