Contamination check of the window of the measuring device

A technology for measuring equipment, windows, used in measuring devices, testing moving boards, optical testing flaws/defects, etc., can solve problems such as sheet failure, contamination, etc.

Active Publication Date: 2016-06-08
GIESECKE & DEVRIENT CURRENCY TECHNOLOGY GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, it has been shown that despite this contamination check, inspected sheets are partially classified as non-conforming, such as contaminated or defective, while the corresponding sheet itself is acceptable

Method used

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  • Contamination check of the window of the measuring device
  • Contamination check of the window of the measuring device
  • Contamination check of the window of the measuring device

Examples

Experimental program
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Embodiment Construction

[0031] FIG. 1 shows a measuring device for inspecting a sheet conveyed through the measuring device on a transport path T in a transport direction x. The measuring device 1 has a housing 7 in which two light sources 4 and four sensor rows 3a-d are received. The sensor rows 3a-d are each only sensitive to a certain spectral range and are equipped for this purpose with corresponding spectral filters, for example. Via the window 6 , light is irradiated by the light source 4 on the surface of the sheet 10 present in the capture area of ​​the measuring device 1 . The light reflected by the sheet surface passes again through the window 6 and, after passing through a suitable optical element 2, eg a lens, is detected by the sensor row 3a-d. In this example, inspection of sheet and window contamination is performed based on reflectance measurements, but could also be performed based on transmission measurements (eg dark field transmission measurements). Measuring devices can also be...

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Abstract

The invention relates to a method for detecting contamination of a window of a measuring device for detecting sheet material, said device comprising at least two sensor rows aligned transversely to the output direction of the sheet material. The sensor banks each detect light from the sheet material in a specific spectral channel. To detect the presence of window contamination, the sensor row detects light at multiple detection instants when sheet material is not present within the sensing range of the sensor row. According to the invention, at least two of the spectral channels are combined and the intensity of the combined spectral channel is evaluated over time to detect contamination. Small changes over time in the intensity of the combined spectral channel act as an indicator that contamination is present on the window.

Description

technical field [0001] The invention relates to a method for checking contamination of a window of a measuring device for inspecting sheets, a measuring device for carrying out the method and a device for processing sheets with the measuring device. Background technique [0002] In devices for inspecting sheets, the sheet is usually conveyed in the transport direction through a measuring device and is illuminated on one or both surfaces in order to detect light reflected by and / or transmitted by the sheet with the aid of the measuring device of light. Between the conveying sheet and the measuring device, a window transparent to the wavelength to be detected is arranged, which prevents mechanical damage or contamination of the sensitive parts of the measuring device. However, such windows become contaminated over time, so that the intensity of light from the sheet detected by the measuring device is distorted by the contamination of the windows. This may cause erroneous jud...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N21/15G01N21/86
CPCG01N21/15G01N21/86G01N2021/157G01N21/94G01N21/84
Inventor D.萨库亚德S.苏
Owner GIESECKE & DEVRIENT CURRENCY TECHNOLOGY GMBH
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