| 摘要 |
1,195,897. Knitting machines. E. SICK. 21 Aug., 1967 [10 Sept., 1966; 12 Oct., 1966], No. 38410/67. Heading D1C. [Also in Division G1] In a photo-electric detector of holes in knitted fabric wherein the fabric is illuminated and/or observed at an acute angle to its surface and the detection of a hole is arranged to stop the machine, the angle is selected so that each thread shadows the interstice between that thread and the adjacent thread and light does not normally pass through. In the presence of a fault light may fall directly on a detector, on to a reflector which may return a beam along the original path or along a separate path, or on to a light guide leading to a detector. Sawtooth banking reflectors which may have planar or concave faces may be provided and' they may be pivotally mounted to keep the reflecting surface normal to the beam as it is scanned across the material. Alternatively, a line of individual reflectors each including a lens arrangement may be provided. The material may be illuminated by a fluorescent tube across its width and through a succession of screening louvres allowing light to impinge on the surface only at the desired angle. In a final embodiment a pencil of light is transmitted across the material surface along the path of a movable reflecting device arranged to scan across the material and any light passing through a hole is made to fall on a synchronously scanning reflector to be returned for detection beyond the edge of the material. Sizes of beam to produce minimal light intensity change during traverse are discussed. The light-guide in the arrangement previously referred to may have a saw tooth surface facing the material and may be terminated in a prism and lens system to feed any penetrating beam on to the detector. |
