| 摘要 |
1,076,712. Warp stop motion for looms. M. A. EAGLE and J. W. RAQUET. June 4, 1965 [June 26, 1964], No. 23998/65. Heading DIE. [Also in Division G1] A yarn breakage detector for a loom comprises a light trap containing a photocell and a collimating lens whose field of view is directed at a further light trap. A light source is offset from this field of view to illuminate any broken yarn which enters the field of view. The photocell comprises a photomultiplier 31 and the 100 or 120 cycle ripple from the mains on the light from a fluorescent tube 58 is detected and applied through a cathode follower to fire a thyratron. The thyratron has a pair of relays in its anode circuit one of which controls a horn and the loom motor and the other of which maintains the thyratron anode voltage during the decay time of a capacitor. The collimating lens 40 may comprise a doublet and is housed in a casing 36 carrying a series of bevelled baffles 43 which serve to define a parallel beam path and a series of stop plates 37 - 39 in the converging light path to the photo multiplier. The distance of the lens from the front 41 of the casing is several times the beam width. The further light trap comprises a series of plates 53 - 57 within a casing 50 having holes with bevelled edges the same diameter as the collimated beam. The interior of the light trap is provided with a light absorptive surface. Light from the fluorescent tube may be focussed into the path by an elliptical reflector or by a cylindrical glass rod.
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