Patent ID: 9279772
Filing Date: 2016-03-08
CPC Classification: G01N

Claim Text:
1. A method for checking the soiling of a window of a measuring apparatus for checking sheet material that is transported past the measuring apparatus along a transport path in a transport direction, wherein the measuring apparatus has respectively one sensor row for at least two different spectral channels, said sensor row having several detection elements along a y-direction transversal to the transport direction of the sheet material, to detect light emanating from a sheet material, when a sheet material is present in the capture area of the sensor row, and has at least one window arranged between the sensor rows and the transport path of the sheet material; and wherein for checking the soiling of the window the intensities of the light impinging on the sensor rows through the window are detected when no sheet material is present in the capture area of the sensor rows; wherein for checking the soiling of the window at least two of the sensor rows with different spectral channel detect respectively at least in one y-position along the y-direction the intensity of the light impinging on the respective sensor row through the window respectively for several detection times, when no sheet material is present in the capture area of the sensor rows, and from the intensities detected by the at least two sensor rows with different spectral channel at a detection time, an intensity of a combined spectral channel is determined, wherein the intensity of the combined spectral channel is determined individually for respectively several of the detection times, and a statistical evaluation is carried out for the intensities of the combined spectral channel determined for the several detection times, and on the basis of the statistical evaluation a soiling check of the window of the measuring apparatus is carried out.