Device for measuring ink density on printed surfaces

摘要

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.