Patent ID: 7084418

Claim:
A method for recognizing a substrate stock within a printing unit, the method comprising the following steps: providing at least one light sensitive sensor, the at least one light sensitive sensor being attached to the printing unit and being able to independently sense several partial ranges of light wavelengths; providing a light-emitting light source, light emitted from the light-emitting light source being reflected by or transmitted through a surface and/or a substrate stock on the surface in the printing unit; sensing several partial ranges of light wavelengths of the reflected or transmitted light with the at least one light sensitive sensor and measuring the luminosity of these ranges of light wavelengths; automatically assigning the measured luminosity of the several partial ranges of light wavelengths a color value within a color area, and comparing the color value with a reference color value and recognizing a substrate stock if the compared color value differs; and ascertaining the reference color value by the sensor through a measurement of the light reflected by or transmitted through the surface on which the substrate stock is to be recognized.