Densitometer.

摘要

The present invention relates to a densitometer having a light source (2) by means of which a light beam (4) is directed upon a printed web of paper (6) as well as a photo electric cell (8) measuring the amount of light reflected by the paper (6) said desintometer having an air jet nozzle (7) by means of which a jet of air can be directed to the spot (5) where the light beam (4) hits the paper (6) said jet preferably being perpendicular to the paper-plane said densitometer allowing a method to control the ink supply to the ink roller of the printing press which press can have a plurality of densitometers each controlling one or more of a number of ink supply members located side by side.