| 摘要 |
<p>1, 171, 633. Electro-physical measurement. ZELLWEGER Ltd. Nov. 7, 1966 [Dec. 13, 1965] No. 49793/66. Heading G1N. In a yarn cleaner of the kind dislcosed in Specification 1, 082, 059, i.e. in which the diameter of the yarn is measured and a first threshold circuit responds to increases in diameter due to slubs in the yarn and operates a yarn cutter, and a second threshold circuit responds to the integral of the measurement signal so as to produce a cut in the presence of a double thread, the threshold sensitivity of the double thread detector is changed temporarily after a cut, i.e. on insertion of the yarn, so as to increase the number of faults detected. In one embodiment, Fig. 7, signals from a measuring head (not shown and not disclosed) are applied at 41 to the slub detector and at 31 to the R. C. network of the double thread detector. The slub detector comprises the Schmitt trigger 53/55 and the double thread detector the Schmitt trigger 51/55. Switching of either of these circuits controls a bi-stable circuit 52/54. The presence of a double thread causes transistor 52 to conduct and remain conductive, thus connecting resistor 56 into the base bias circuit of transistor 55 instead of resistor 57. If resistor 56 is made larger than resistor 57, the sensitivity of the double thread detector is increased. This is desirable because after cutting a double thread, the chances are that the same fault will continue further along the yarn and could be missed on reinsertion due to the action of the integrating network. When a slub is detected, the bi-stable circuit 52/54 is reversed, and the sensitivity of the double thread detector is returned to normal. It is stated that as an alternative, the slub detector alone can switch the bi-stable circuit so as to reduce the sensitivity of the double thread detector after a slub (instead of increasing it after a double thread) the sensitivity being returned to normal either after a time-delay after reinsertion of the yarn, or on receipt of a signal from the measuring head that the yarn is running.</p> |
