Man Roland Druckmaschinen Ag

Hans Joachim Six

Karsten Wendt

Peter Rakitsch

Franz Lampersberger

Rainer Tutsch

Bernd Tieleb&ouml;rger

J&ouml;rg Sierks

A measurement device is described for the quality control of printed products, having a pair of optical channels that differ in their properties and operate simultaneously. Each optical channel comprises an illumination channel for illuminating a measurement location and a reflection channel that picks up the light reflected from the measurement location. The reflected light is directed to an evaluation unit, which is connected to the reflection channel, that analyzes the reflected radiation spectrally. Polarization filters arranged in one of the pairs of channels provides the difference in the optical properties between the two pairs of channels. The measuring device provides an increased number of obtainable measured values for further processing in a way that requires only a modest increase in the metrological outlay compared to other measuring devices of this type.

Measuring device for the quality control of printed products

A measuring system for registering reflectances on printed products, the measuring system having at least one illumination channel for producing a scanning spot at a point on a measurement field on the printed material. The system includes scanning channels for registering the reflectances of the spot from the printed material. The measuring system moves relative to the printed material. Measuring devices supplying ink density and spectral, preferably colorimetric, measured values are combined with one another without additional outlay in terms of construction. The combination of the measuring principles (density and color) are optimally adapted to the task of a measuring strips on the printed material scanned in the longitudinal direction. The measuring system has a densitometer that produces a scanning spot on the printed material, and a spectrophotometer that produces a further scanning spot on the printed material. The densitometer and the spectrophotometer are arranged one behind the other in the measuring head. The scanning spot of the densitometer and the scanning spot of the spectrophotometer are spaced apart from each other by a distance determined by the speed of the measuring system in the scanning direction and by the computational speed of the evaluation electronics, which are connected downstream of the densitometer and the spectrophotometer. The measured values from the densitometer may trigger the measurements and/or evaluations of the measured values obtained by the spectrophotometer.

Measuring system for registering reflectances on printed products

A method for controlling the ink feed of a printing machine, especially an offset printing machine, for printing four-color half-tone combined prints. In selected test regions in an original and in the corresponding test regions in the printed sheet, the standard color values of the four-color overprint are determined. The infrared color density for the black printing ink is determined in the near infrared. The standard color values of the four-color overprint are converted by means of a linear transformation into standard color values corresponding to the combined print of only the three chromatic colors. The coefficients of the linear transformation are determined empirically as a function of the infrared color density of the black printing ink. From the standard color values of the three-color print, the effective surface coverage values of the three chromatic colors are determined via the modified Neugebauer equations. The effective surface coverage value of the black ink is determined from the infrared color density according to an empirical relationship. The settings for the ink feed elements of the printing machine are adjusted according to the differences in the effective surface coverage values between the original and the printed product.

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Munich, Germany

Hans Joachim Six