In the prior art of devices for replenishing thread on a bobbin in place in a sewing machine loop taker, various means have been taught for positively retaining or anchoring the needle thread end at the initiation of bobbin winding, such as that disclosed in U.S. Pat. No. 3,099,972, Aug. 6, 1963, of Johnson et al. Applicants are unaware of any disclosure or teaching in the prior art of controlled release or pay-out of the nipped needle thread end to facilitate thread introduction to the bobbin and uninterrupted initiation of bobbin thread replenishment.
Modern mechanisms for replenishing thread on a bobbin while the bobbin remains in place in the sewing machine loop taker include a friction clutch device in the drive train for rotating the bobbin during the bobbin thread replenishing process, such as the clutch device 132 disclosed in U.S. Pat. No. 4,515,099, May 7, 1985, of Gerald J. Creed, which is incorporated herein by reference. The function of the spring clutch in the drive for the bobbin during thread replenishment is to release the drive in case excessive resistance to turning of the bobbin is encountered, as for instance, if overwinding of the bobbin is inadvertently attempted, so as to prevent damage to the delicate and critical parts of the sewing machine loop taker.
It has been found that where the needle thread end is positively anchored during initiation of bobbin thread replenishment, the static friction acting upon the supply limb of needle thread, even though the needle thread tension device is released can at times be sufficient to exceed that which is necessary to override the friction clutch device in the drive train for rotating the bobbin. Where this occurs, an annoying interruption of bobbin thread replenishment results.