Soiling check of the window of a measuring apparatus for checking sheet material
AssigneeGiesecke & Devrient GmbH
InventorSteffen Schmalz
Life of this patent
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Abstract
A method carries out a soiling check of the measurement window of a measuring device for checking sheet material. A measuring device carries out the method. A device for processing a sheet material comprises the measuring device. The soiling check uses, only areas of the measurement window which correspond, in terms of width and position in the beam path of a light, to the areas of the checked sheet material which are checked during the checking of the sheet material. As a result, fewer cleaning steps are needed for the measurement window.
Claims15
A method for a soiling check of a window of a measuring apparatus that is formed for checking a sheet material that is transported along a transport path past the measuring apparatus, and which has
- at least one light source for irradiating the sheet material,
- at least one sensor line for detecting a light emanating from the sheet material, the sensor line having at least the width of the sheet material,
- at least one evaluation device for the evaluation of a light signal that was detected by the sensor line upon the detection of the light, and
- at least one window between the sensor line and the transport path of the sheet material,
- wherein in phases in which the sheet material is in a detection region of the sensor line, the method comprises the measuring apparatus carrying out a check of the sheet material, upon which there is checked only at least one partial region of each sheet of the sheet material, which partial region has a specified length and width and altogether is narrower than the width of the sheet material, through detection and evaluation of a light emanating from the at least one partial region of the sheet, and
- wherein in phases in which no sheet material is in the detection region of the sensor line, a light emanating from the window is detected and evaluated for the soiling check of the window,
- wherein, the soiling check of the window does not evaluate the entire area of the window but only evaluates a light that emanates from a partial region of the window through which, upon the check of the sheet material, the light reaches the sensor line and which with respect to its width and its location in a beam path of the light corresponds to that at least one partial region of the sheet material that is checked upon the check of the sheet material.
A measuring apparatus for checking sheet material that for its check is transported along a transport path past the measuring apparatus, comprising
- at least one light source for irradiating the sheet material,
- at least one sensor line for detecting a light emanating from the sheet material, which sensor line has at least the width of the sheet material,
- at least one window that is arranged between the sensor line and the transport path of the sheet material,
- at least one evaluation device for evaluating light signals that are detected by the sensor line upon the detection of the light,
- wherein the window, the light source and the sensor line are arranged such that upon operation of the measuring apparatus the light source radiates light on the window and, where applicable, the sheet material arranged adjacent the window, and the sensor line detects a light emanating from the window and, where applicable, the sheet material, and the evaluation device for checking the sheet material is designed to check only at least a partial region of the sheet material to be checked, which partial region has a specified length and width, but altogether is narrower than the width of the sheet material, through detection and evaluation of a light emanating from the at least one partial region of the sheet material,
- wherein the evaluation device is configured, for the soiling check of the window, to not evaluate the entire area of the window but only to evaluate a light that emanates from a partial region of the window, through which, upon the check of the sheet material, the light reaches the sensor line, and which with respect to its width and its location in a beam path of the light corresponds to the at least one checked partial region of the sheet material.
Dependencies are inferred from the claim text.