Veb Kombinat Polygraph 'Werner Lamberz Leipzig'

Helmut Weigend

Bernd Morgenstern

Peter Reinhardt

Gudrun Dietrich

A series of equidistant measuring heads is arranged at a uniform distance above a surface to be measured. Each head includes a light source emitting light through a narrow exit opening, and two light sensors arranged adjacent the opposite narrow sides of each opening. The light input characteristic of respective sensors is such that light reflected from the measured surface section is detected with a sensitivity which is inversely proportional to the different intensity of illumination of central and marginal points of the measured section.

Device for determining surface proportion of a printed pattern for

In a method for measuring ink density of printed sheets by means of photodiodes which scan light reflection from measuring marks provided on printed sheets, the start of a dynamic measuring process during the running of the printing machine is released by the control of impulse flanks, and the reflected light is scanned by sensors having a short response time. A medium reflection value of the surface of the measuring mark is determined. The control of impulse flanks takes place by a leading edge of the mark printed on the sheet, and the signal, released by that control, switches on the photodiodes and the light source. A changed voltage occurring at the output of each photodiode is amplified, and its peak value is stored; and the photodiodes and the light source are switched off thereafter.

Method for measuring ink density

A densitometric head for measuring ink density of prints in a running printing machine includes a light source for transmitting light on the measured surfaces and sensors for receiving the remitted light. To simplify the construction and eliminate heat effects of the light source, the latter is arranged in one focal point of an elliptic reflector whereas the measured surfaces are situated in or close to the other focal point where an image light source is formed from the light reflected in the reflector. A heat protective filter is arranged between the two focal points to eliminate heat effects on the sensor.

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Leipzig, Germany

Helmut Weigend