Other reasons apart from contamination can be the

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Unformatted text preview: r, on reaching the switching threshold, the optical signal capacity has increased to a level which still leaves sufficient operating margin. For this mode of operation, switching operations are presumed to take place. An LED flashes, if there is insufficient operating margin or an electrical warning signal is provided at an additional output. Other reasons, apart from contamination, can be the cause for falling below the operating margin, e.g.: – Exceeding of safe sensing range – Changes in the material surface of objects detected – Incorrect assembly (maladjustment) – Ageing of emitter diode – Fracture in fibre-optic cable 6.1.4 Variants of optical proximity sensors Schematically, the variants can be divided as follows: Optical proximity sensors Light barriers Diffuse sensors Through-beam sensors Retro-reflective sensors Designs with fibre optic cable Designs with fibre optic cable Designs with fibre optic cable Fig. 6.1.6: Variants of optical proximity sensors © Festo Didactic...
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