| 摘要 |
1,185,722. Detecting fabric flaws photoelectrically. APPALACHIAN ELECTRONIC INSTRUMENTS Inc. Aug. 29, 1967 [Dec. 15, 1966], No. 39414/67. Heading G1A. In a knitted fabric flaw detecting apparatus for stopping the knitting machine when a flaw occurs, a movable sub-assembly is reciprocated by a motor driven cable or cord and magnet and reed limit switches along a path across the fabric as it emerges from the machine so that photo-electric means, which may be a photo-transistor, carried by the assembly produces a signal in response to a variation in the light from a source also on the sub-assembly reflected from the fabric or from beneath the fabric in the event of a flaw, and the circuitry is accommodated in two housings, one mounted on the movable sub-assembly and the other fixed, inter-connected by brushes engaging electrical contact strips extending along the path, a flaw signal varying the current drawn by the circuitry in the sub-assembly to cause the production of a stopping signal in the fixed housing. The motor stopping circuits includes relays and a silicon controlled switch. The trolley rail is an upwardly opening, channel-shaped formation carrying the contact bars on insulation panels at different vertical levels on opposite inside faces, and the trolley is supported by wheels operating respectively on downturned channel rims and obliquely in the lower corners of the channel, and separated by compression springs to prevent wobble. The current drawn by the sub-assembly circuitry is diminished by cutting off the current to the lamp and the machine is stopped. The operator then closes a start switch to operate a reversing motor and to introduce a time-delay into the detecting circuit to prevent a further shut down by the flaw. A switch is also provided to enable actuation of the detecting apparatus with the machine stopped so that the sensitivity may be adjusted and during this time, time-delay in the detecting circuit is reduced to permit more rapid adjustment. A suitable regulated D. C. power supply is described and a capacitor is provided across the shut down relay to prevent spurious actuation due to momentary loss of bus-bar contact. A single photo-transistor, or a pair of photo-transistors actuated by a flaw in one before the other, may be used, and light may be reflected by a strip beneath the fabric. The stopping apparatus may be rendered ineffective over desired areas. A Darlington amplifier including noise attenuating filters is described. |
