| 摘要 |
<p>991,038. Cutting-machines. E. K. COLE Ltd. Nov. 14, 1963 [Nov. 15, 1962], No. 43160/62. Heading B4B. [Also in Divisions B6, G3 and G5] In a Control apparatus for a machine of the type wherein a body in the machine and a magnetic track are advanced forwards step by step and in synchronism to a position where an operation is to be performed on the body, a pick-up head is adapted to be moved backwards over a predetermined length of the track during each stopping period, the backward movement of the head increasing the relative speed between the track and the head so that any signal received by the head during its backwards movement is of sufficient amplitude to be subsequently used to control the operation of the machine. The machine may be a paper-cutting guillotine wherein marks such as 4-6, Fig. 1, are recorded on a magnetic tape or wire 1. When the mark 4 passes a pick-up head 2 a pulse induced in the head causes slowing down of the back fence and the tape. When the mark 4 passes head 3, the back fence is stopped so that a cutting operation may be carried out. Whilst the tape 1 is stopped or moving slowly a pulse 5 may be missed by the head 2, and this is avoided by moving the head 2 backwards during the stopping period; means are provided to prevent a second pulse, which may be produced by a mark when the tape is re-started, from passing to the utilization circuits. Control circuit.-A pulse from the " stop " head 3, Fig. 2, passes through processing circuits 13-15 to operate the motor switch 16 and the knife control 17, and also triggers a multivibrator 18. The latter operates a solenoid 20 which moves the head 2 backwards by a predetermined distance. If a pulse is detected by head 2 during this movement, it passes through processing circuits 7-9 and a gate 10 to a store 11 so that when the back fence moves again it will do so at the slow speed. The gate 10 is opened via unit 22 when multivibrator 18 is triggered and is closed again when multivibrator 18 returns to its initial state and head 2 returns to its initial position. When a cut has been made and the back fence commences to move at its slow speed, a signal is fed from a knife-operated switch to remove the pulse from store 11 and to close the gate 10 for a short time so that a pulse produced by a second passage of mark 5 past head 2 does not pass to the store 11. Two tapes with the same information may be used and the outputs of two stop heads fed to a coincidence gate at the input of unit 17 so that a spurious pulse on one of the tapes will not cause the knife to be operated.</p> |
