GB1024546A - Improvements in and relating to an apparatus for monitoring the thread in a textile bobbin-frame - Google Patents

Abstract

A method for controlling the thread in a textile bobbin frame by means of monitoring the thickness of the thread is characterised that when the thread thickness deviates from a predetermined range the length of the faulty thread section having the deviation is ascertained and used to initiate a control process-for example to cut or clean the thread, or to stop the machine or a counting mechanism, or to photograph the thread. The thickness modulating device may comprise capacitor plates, or a photocell which may be modified to measure the average thickness of the thread in a plane normal to the length of the thread. The electrical output from either device is used to modulate a signal voltage. The resulting wave form 31, Fig. 4 (not shown) is passed through a discriminator to produce a series of pulses 32 corresponding in number and length to the faulty thread sections. The subsequent processing step may be initiated when the length of a pulse is greater than a threshold value, or the lengths may be integrated so that the "resulting length" if greater than a certain value, is used to initiate the processing step. In Fig. 4 wave 32 is integrated to form a zig-zag wave which is increased in height during a pulse, and decreased in height during the absence of a pulse, with the height of the wave being the "resulting length". In Fig. 7 (not shown) the wave is integrated to form a stepped wave 38 which is periodically interrogated to obtain the resulting length, and at the same time is reduced to zero. Alternatively a function of the length L of the faulty thread section and of the maximum amplitude a of the thickness of the thread may be used to initiate the processing step if the function exceeds a threshold value. In Fig. 6 (not shown), the signal is passed through an amplifier 5, a length channel comprising a Schmitt trigger 119 and a Miller integrator 120, a linearly operating amplifier 118, a combining circuit 127 which adds the resulting length wave form and the amplitude, and a discriminator 7 whose threshold is regulated by rectified and smoothed the signal wave from amplifier 5. In Fig. 11 (not shown) the signal voltage is fed to trigger and modulator which produces a pulse of length L and height proportional to a, which pulse is fed to an amplitude discriminator, an integrator, and a length discriminator. In Fig. 12 (not shown) the outputs from an amplitude discriminator and a length discriminator are fed into a coincidence circuit. In Fig. 14 (not shown) a pulse of length L and height a is fed to a combining circuit which produces a pulse of amplitude proportional to aL2. The stepped wave form 38 of Fig. 7 may be obtained optionally by using light source, lens, slot and photo-element-Fig. 9 (not shown). The position of the thread is adjusted so that only the image of the faulty thread section fall across the slot and thus causes a signal in the photo-element.