Gretag Imaging Ag

Gretag Imaging Trading Ag

Guido Keller

Markus Landolt

Armin K&uuml;ndig

Stephan Waldner

A process for the reduction of artefacts during the reproduction of an image based on image data and having a plurality of image points, by a specific image reproducing device is disclosed, whereby the image points have appearance properties, the process including the following steps: device characteristics which describe the appearance properties of image points produced by the specific image reproducing device in answer to image data and describe the dependence of the appearance properties on the position assigned to the image data, are provided or input, reproduction image data are input, and the image data corrected based on the device characteristics and depending on the positions assigned to the image data.

Reduction of artefacts in reproduced images

An apparatus for printing on sheet material is set-up in a modular fashion having physically added modules, particularly having modules stackable one on top of another, each module including a printing mechanism. The apparatus also includes a modular distributor unit that is distributed amongst the modules for distributing the blank sheet material to the available modules and, if required, for bringing together printed sheet material and for sorting the printed sheet material. The modules are designed such that they can be easily stacked one on top of another, so that no cabling or wiring has to be carried out. The connection of the individual modules with each other is made through a bus system having corresponding connection and expansion interfaces, for example in the form of plug-in connections. A central control unit is provided in a base module, which central control unit recognizes the connected expansion modules through the bus system and configures itself. The central control unit independently distributes the queued printing jobs to available modules and hence achieves optimally short run times for each individual job. The capacity parameters of the printing apparatus can be co-ordinated exactly with the needs of the user by means of the module concept.

Apparatus for printing on sheet material

An image-recording drum apparatus includes a rotatably driven clamping drum (,), means (,) for the fastening of a recording medium (M) on the mantle (,) of the clamping drum and a recording unit (,) which is stationary relative to the direction of rotation of the clamping drum and records on the recording medium (M) fastened onto the mantle of the rotating clamping drum (,) image information fed thereto in the form of electrical signals. Mounting means (,) are provided in the interior of the clamping drum (,) for supporting a supply of recording medium (M) wound up into a roll (,). The clamping drum (,) has a slit (,) in its mantle (,) through which the recording medium (M) can be guided from the interior of the clamping drum (,) to its mantle (,) and fastened thereon. The feeding of the recording medium from the interior of the clamping drum is on the one hand constructively especially simple and advantageous and on the other hand permits the cutting of the recording medium only after the recording of the image information to the respectively required exact length without generating clippings. The picture format can thereby be arbitrarily varied within the available length of the clamping drum circumference which permits a very flexible and economical operation of the recording apparatus (FIG.,).

Recording drum arrangement

A loop buffer having an input and an output deflector roll and a loop roll flexibly mounted between them in a basically vertical position, with its height relative to the deflector rolls determining the loop length of the strip material to be transported. The loop roll is gravity tensioned via a relatively weak spring by a ballast body guided with free movement in a basically vertically direction. The loop roll also includes two or three parallel coaxial loop wheels of slightly different diameter, adapted to the thickness profile of the strip material, transverse to the longitudinal direction. By selecting a relatively weak spring, the loop roll can follow small but quick changes in the transport speed very easily and quickly, with the acceleration forces caused by tile low inert mass of the moving parts remaining very low. Larger drift movements of the loop roll because of speed differences of greater duration between the feeding and removal of the strip material have the effect of displacing the ballast body, the gravity tensioning of the loop roll and thus the tension exerted on the strip material always remaining constant.

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Adlikon, Switzerland

Guido Keller