Oce-technologies B.v.

Ronald Fabel

Peter George La Vos

Frederik Gerardus Heeman

Cornelis W Venner

Berend J W Waarsing

Johan Hendrik Burger

Romeo Maria Van Strijp

Antonius H Habets

An image reproduction device for document processing has a nominal processing speed at which it can process sheets continuously at a nominal document quality. However, the image reproduction device is arranged to process sheets at a continuously variable processing speed including the nominal processing speed. The actual processing speed is selected in dependence on operational conditions. In particular, the device is arranged to gradually adjust the processing speed from one processing speed to another processing speed. A control structure is given to select the variable processing speed in dependence on operational conditions, and to operate the image reproduction device at the selected processing speed. In a particular application of the variable speed, a print job may be started at an increased processing speed and then gradually fall back to the nominal speed, giving a fast start and a shorter processing time for short print jobs.

Variable speed printing

A method of and apparatus for printing color images by the superimposition of a number of separations, using a first half-tone technique optimized for surface reproduction, such as dithering, and a second half-tone technique, differing from the first and optimized for edge reproduction, such as thresholding with error diffusion, is disclosed. The second half-tone technique is used in edge transitions for pixels of a separation which substantially influences the edge transition, and the first half-tone technique is used outside the edge transition. And the first half-tone technique is used throughout in the case of pixels of a separation which provide no or minimal contribution to the edge transition.

Printing of digital color images with locally adjusted half-toning

An image printing apparatus includes a number of image forming units for forming toner images of different colors in alignment on image receiving material in accordance with electronic image information signals fed to each image forming unit. Each image forming unit includes an image forming element rotatable about an axis of rotation and provided with a dielectric surface layer with adjacent electrode tracks in the direction of rotation. Each image forming unit further includes developing devices which include a linear developing magnet situated near the outer surface and parallel to the axis of rotation of the image forming element, toner feed devices for feeding a complete covering of electrically conductive and magnetically attractable toner powder to the image forming element, electrode track activating devices for applying a first or a second printing voltage between an electrode track and the magnet system in accordance with the image information signals to be fed to the image forming units. Toner powder on the passage of the electrode track along the developing magnet remains either on the image forming element or does not remain thereon in the event of a first or second printing voltage respectively on the electrode track. The image printing apparatus also includes at least one image forming unit provided with electronic image line correction devices for feeding image line correction signals to the electrode track activating devices in order to shift in time for each electrode track a printing period in which a printing voltage is applied to the electrode track in accordance with an image information signal.

Image printing apparatus

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Venlo, Netherlands

Ronald Fabel