| 摘要 |
The invention provides an arrangement for detecting faults in wrapped filter rod, for tobacco-smoke filtration, prior to its being cut into lengths, the arrangement comprises a light source and a light-sensitive receiver, for example a photo-transistor, in a housing provided with a rod guide which imposes on the rod a path between and spaced away from the said light source and receiver, a beam of light from the said source being projected through the said path of the rod to the receiver. Advantageously the housing bounds a cavity from which extraneous light is excluded and the light source and receiver are disposed behind respective transparent windows spaced away from the said rod path. The said receiver may be operatively connected to a system by which a faulty rod length detected is caused to be rejected after having been cut off from the rod.
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