Patent ID: 6150946
Filing Date: 2000-11-21
Classification: G01V

Abstract:
An optoelectronic monitoring unit employing an emitted and received test beam of light for detecting material webs and/or blanks of packaging material in conjunction with packaging machines, the monitoring unit (10) comprising:a) a U-shaped monitor housing (13) formed by opposing subassembly arms (14,15) and a connecting wall (27) extending between and joined to the subassemblies;b) at least one transmitter (11) operatively positioned in one of the subassemblies and a receiver (12) operatively positioned in the other subassembly,c) the facing walls (19, 20) of the subassemblies comprising a light-transmitting material through which the test beam passes,d) an air line (21) communicating with the interior of the monitor housing (13) for supplying compressed air to the interior of the housing,e) a plurality of air discharge holes (25) extending through the monitor housing walls proximate the junction of the connecting wall (27) and the adjacent subassembly,f) the air discharge holes (25) being positioned to direct a jet of compressed air from the interior of the housing (13) onto the exterior surfaces of the light-transmitting wall faces, whereby the exterior surfaces of the light-transmitting wall faces are kept free of dust by the directed jets of compressed air.