Patent ID: 9743008
Date: 2017-08-22
CPC Classifications: G01B,H04N

Claim:
1. A sensor for capturing a position of a moving material web having a surface with a region, comprising a marking provided on the surface of the moving material web within the surface region, the surface region also including a surface portion outside said marking, wherein said marking is situated under a coating of clear varnish on the surface of the moving material web, said marking having a position being captured by said sensor, wherein said sensor comprises at least one light source transmitting emission light to said region of said material web and said emission light being influenced by said material web producing detection light, said sensor further comprising at least one light detector, which receives said detection light, wherein in order to achieve a high contrast between said s region outside said marking of said material web and said marking, at least one polarization element is provided between said at least one light source and said at least one light detector, said at least one polarisation element being penetrated by said emission light, said sensor further comprising capacitor electrodes, producing an electric field that influences said polarization of said emission light by way of applying an electrical voltage between said capacitor electrodes, wherein said at least one polarization element is arranged spatially between said capacitor electrodes, and wherein said at least one light detector is configured as a camera.