Heidelberger Druckmaschinen Ag

Linotype-hell Ag

Axel Heuer

Holger Suhr

Axel Gebhardt

Helmut Lange

Bernd Lassen

Rainer Schielke

Udo Wurdemann

In a method for white balance of an optoelectronic color scanner element of a color scanner device for pixel-by-pixel and line-by-line scanning of a color original rated voltage values are calculated from the optical densities of the white point of the color original and a predetermined white level. Scan light that represents the optical density zero of the color original is simulated with an illumination means and is converted in actual voltage values in a light/voltage transducer means. The gains of the light/voltage transducer unit are set such and held constant for the duration of the following originals' scanning such that the actual voltage values are equal to the calculated rated voltage values, it being thereby achieved that the color signals of the white point correspond to the white level in the later scanning of the original. For light attenuation of the simulated scan light, scan diaphragms of a diaphragm wheel employed as balance diaphragms can be additionally introduced into the beam path of the scan light.

White balancing method

In an apparatus for point-by-point and line-by-line, opto-electronic scanning of masters chucked on a scanner drum, an illumination unit is provided for generating an illumination spot on the master. A scanner objective, a scanner element and a feed support is provided at which the illumination unit, the scanner objective and the scanner element are arranged. The illumination unit comprises a light conductor that is aligned in the direction of the rotational axis of the scanner drum and has a light exit face for generating a light spot and has optical elements for imaging the light spot onto the master as an illumination spot. At least a sub-section of the light conductor in the region of the light exit face can be inclined by small angles relative to the rotational axis with a Cardanic bearing for fine adjustment of optical beam paths, as a result whereof the illumination spot is displaced on the scanner drum. The slope of the light conductor that has been found to be optimum is then fixed.

Apparatus for scanning masters

In a method and an apparatus for point-by-point and line-by-line scanning of a master chucked on a scanner drum, for pixel-by-pixel illumination of the master, a light spot is generated in a light conductor and is imaged onto the master as illumination spot. The light conductor is arranged displaceable with an actuating drive for the purpose of modifying the imaging scale of the illumination spot. For setting the illumination, the luminance of the illumination spot is measured with the opto-electronic scanner element. In a computer, control signals for the actuating drive are generated dependent on the measured luminance. For setting the optimum illumination of the master, the imaging scale of the illumination spot is modified such by displacing the light conductor that the measured luminance of the illumination spot is maximum.

Method and apparatus for scanning masters

In a method and apparatus for point-by-point and line-by-line scanning of masters chucked on a scanner drum, for pixel-by-pixel illumination of the master, a light spot is generated with a light conductor, the light spot being imaged by a matching objective onto the master as an illumination spot. The scan light is focused with a scanner objective and is converted into an image signal in an opto-electronic scanner element. The illumination spot, scanner objective, and scanner element implement a feed motion in the direction of the rotational axis of the scanner drum for planar scanning of the master. Given employment of scanner drums having different diameters, the size of the illumination spot is corrected by a modification of the imaging scale of the light spot. The modification of the imaging scale occurs by displacing the light conductor with an actuating drive relative to the stationary matching objective. A corresponding focus correction occurs with a radial displacement of the scanner objective.

Method and arrangement for scanning masters

In a device for point-by-point and line-by-line scanning of masters chucked on scanner drums having different diameters with an optoelectronic scanner element, which converts the scan light modulated with the content of the master and focused with the scanner objective into an image signal, a scanner element comprising a reflected light illumination is provided for generating an illumination spot on an opaque original. The scanner objective for correction of the focusing of the scan light onto the scanner element given employment of scanner drums having different diameters&mdash;is seated displaceable on the optical axis of the scanner element into radial working positions determined by the diameter of the respective scanner drums. The reflected light illumination can be displaced in the direction of the optical axis by the focal intercept change of the scanner objective for the purpose of optimizing the illumination spot given employment of scanner drums of different sizes.

Scanner device

In a process for calibrating an optoelectronic scanning member of a scanner which scans an image point by point and line by line and converts the modulated scanning light into image values in a light/voltage converter, converter densities are first determined and stored as a converter density table depending on different degrees of amplification of the light/voltage converter. The densities of the scanning diaphragms and grey filters used are also determined and stored as diaphragm density and grey filter density tables. A scanner-specific calibration is carried out with a reference diaphragm by adjusting the degree of amplification so that the image value corresponds to a predetermined white level. When a document-specific calibration is later carried out, the required amplification is automatically determined from the stored density tables and the white point density of the document in question. The light/voltage converter is then adjusted accordingly. This calibrating process considerably shortens the time of preparation required for scanning a document and discharges the operator from routine calibration tasks.

Process for calibrating a scanner

Method for white balance

A method and an apparatus for setting the sharpness of an optical imaging system by step-by-step adjustment of the distance between a subject and an objective and by evaluating the sharpness values identified for the individual distances. First, the sharpness values (S) for two distances (R) modified proceeding from a prescribed distance (Ro) by a respective step width in both adjustment directions are identified and the best sharpness value is determined by comparing these sharpness values (S) to the sharpness value (So) for the prescribed distance (Ro). Respectively two distance points (R1 through R4) having defined step widths proceeding from the prescribed distance (Ro) are then identified in an allowed range of adjustment (VS) and the appertaining sharpness values (S1 through S4) are identified. After this, straight lines (G1; G2) are placed through respectively two of the sharpness values (S1 through S4) to the left and right of the sharpness value (So), these being the tangents at the function curve (V) of the sharpness values (S) dependent on the distances (R). The intersection of the straight lines (G1; G2) and the distance value (Rmax) belonging to the intersection are then identified, this yielding the maximum sharpness value (Smax).

Growing community of inventors

Fahren, Germany

Axel Heuer