| 摘要 |
PCT No. PCT/EP90/01425 Sec. 371 Date Apr. 16, 1991 Sec. 102(e) Date Apr. 16, 1991 PCT Filed Aug. 25, 1990 PCT Pub. No. WO91/02941 PCT Pub. Date Mar. 7, 1991.An edge sensor for a moving web of material includes an elongated light source on which is mounted a receiver containing an active receiver element made of a plastics material with light-absorbing properties. The receiver element comprises an elongated light input surface and at least one light exist on which a light detector is provided. The receiver element is an elongated hollow body made of a light-absorbing plastics material which is supported directly in the receiver in such a way that is light input surface is directly exposed to the light from the light source which falls on the web. A hollow body which is, or can be made, self-supporting directly and without accessories results in a simpler structure and optimal use of light. The hollow body is particularly suitable for use in the tube supports of a standard commercial fluorescent tube housing.
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