Patent GB-932180-A (GB)
Title: Improvements in or relating to the manufacture of sutures
IPC: C14B21/00
Filed: 1961-06-27
Abstract: 932,180. Photo-electric sorting of sutures. AMERICAN CYANAMID CO. June 27, 1961 [Aug. 29, 1960], No. 23195/61. Class 40 (3). Apparatus for sorting surgical sutures in accordance with their minimum diameter includes feed rollers and faster driven tension rollers having a photo-electric measuring position between them. The faster tension rollers serve to prevent whip as the sutures pass through the measuring position. The feed rollers are preferably driven by a small induction motor with a comparatively high slippage which is reduced during transit of the suture through both sets of rollers due to pull along the suture by the tension rollers. Guides with funnel-shaped entrances are provided to direct the sutures to, between, and from, the rollers and measuring position and one roller in each position is a spring-loaded idler so constructed that an electric circuit through it and the corresponding driven roller is broken to indicate the presence of a suture (Figs. 3, 4 and 5, all not shown). The sutures, which average some five feet in length, are drawn from the feed rollers into a holding tube by the application of a partial vacuum and are drawn from thence into the sorter as soon as the latter has disposed of the previous sample and reset. The sorter is shown end-on in Fig. 6. A long roller 76 with a groove 77 dimensioned to hold a suture is normally at rest with the open side of the groove closed by another roller 78. In this position suction applied by vacuum line 79, and more powerful than that applied to the holding tube, draws any suture held in the holding tube lengthwise into the groove. On the basis of the diameter investigation made at the measuring position sutures are directed to troughs 64, 65, 66 and 67 with oversize samples dropping to trough 68. Direction into one of the containers for the size-sorted samples is by means of one of deflection vanes 70, 71, 72 or 73 operated by an appropriate solenoid 74 against a spring 75. After the path to the correct trough has been prepared, the rollers 76, 78 rotate to allow the suture to drop out of the groove 77. If necessary, a short air blast supplied over line 84 may be used to dislodge it. Two measuring systems are described. In the first of these (Fig. 1) a light spot derived from a flying spot scanner or a rotating mirror drum scans repeatedly across the suture as it passes through the measuring position and is received by a photo-multiplier. The output pulses caused by the obstruction of the light beam are differentiated and the front edge signals used to open gate circuits allowing pulses from an oscillator to flow to four counters preset for the different size divisions. At the completion of the preset count these counters reset and close the pulse gate feeding them and also a corresponding signal gate. Trailing edge signals from the differentiator pass through the signal gates which have not been closed to operate thyratron memory circuits. Closure of the circuit through the feed rollers indicates that the end of the suture is approaching the measuring zone and disables the measuring apparatus whilst closure of the circuit through the tension rollers causes a minimum diameter indication signal to be fed to the bin selector control. Signal lights may be used to indicate the minimum diameter registered. In a different type of measuring system (Fig. 2) a collimated beam of light from lamp 87 is directed to a plate 89 in the measuring position. The plate is provided with two slots, each parallel to the suture path. One of these separates out a reference beam subsequently directed to detector 95 whilst the other is adjustable and defines a measuring beam partially obstructed by the suture and directed to detector 96. The relative amplitude of the signals from the two detectors is a measure of suture size and may be indicated on the meter or cathode-ray tube of a monitor as well as being fed through a multivibrator acting as a parametric amplifier to a group of stages having different amplifications. These each control the thyratron associated with a memory circuit as in the first embodiment. Calibration of this system is by the use of wires of known sizes and micrometer adjustment of the measuring beam slot.