Patent GB-685032-A (GB)
Title: Improvements in or relating to means for recording and reproducing teleprinter signals
Inventor: WEIR DONALD ADAMS
IPC: G11B15/18
Filed: 1947-10-24
Abstract: 685,032. Telegraph systems. STANDARD TELEPHONES & CABLES, Ltd. Oct. 22, 1948 [Oct. 24, 1947], No. 28474/47. Class 40 (iii). Apparatus for electrical recording of signals each consisting of a group of code elements of two different kinds preceded by a start element and followed by a stop element, for storing the signals and for reproducing the signals when required, comprises a recording head for recording the signals lengthwise upon a tape of magnetic material or carrying uniformly distributed magnetic material, a reproducing head, a storage container for holding the tape in folded form, means for drawing the tape past the recording head and operative under the control of the start and stop elements of the received signals and independent means for drawing said tape from said container past the reproducing head when required. The tape 4 which may be of polymerized vinyl chloride having a coating of magnetic material or in which the magnetic material is embedded, is drawn past a recording head 1 by a roller 6 intermittently clutched to a constantly rotating shaft in combination with a roller 7 mounted on a spring-biased arm 8. The recorded tape is passed to a narrow deep container 3, Fig. 1, from which it is drawn past the reproducing head 2 by a roller 14 driven from an independent shaft. The container 3 may be replaced by two containers 12, 13, Fig. 2. The code employed has a negative start element and a positive stop element and the release of relay 10 by the start signal closes the circuit of the clutch mechanism 11 to release the sleeve connected to the roller 6 which in rotation through 90 degrees records the signal. The stop element of the signal is such that the circuit of the clutch 11 is open and a detent member arrests the shaft carrying the roller 6. For reproducing, the circuit of the clutch magnet 15 is closed at a terminal 16 and the magnet locks up over contact 17 until the signal has been reproduced. The signals generated by the reproducing head 2 are passed to a flip-flop device 44 and thence to a relay 40 having marking and spacing contacts. These signals are regenerated and corrected, if necessary, in respect of length by apparatus shown in Fig. 3 and comprising a shaft controlled by a clutch magnet 19 energized when the start element moves the armature 41 to the spacing position. A disc 18 provided with seven projections is arranged to close contacts 20 connected to the armature 41 of the reproducing relay 40 operated by the flip-flop and also to the coils of two polarized relays 21, 22. A contact 26 is operated when the clutch magnet 19 is energized. Relay 21 controls a contact 24 in the circuit of a slow-release relay 23 having a release time of approximately <1>/3sec. and relay 22 transmits the regenerated signals to the outgoing line. When the tape carrying the signals is used in a telegraph exchange system to control transmission to a previously engaged line, the message is prefixed by a long marking signal and if the external circuit fails during the transmission of the message, a reversal relay is energized and at terminal 37 closes the circuit of a clutch magnet 39 over the normally closed contact 38 associated with the relay 23. When the reversely fed tape reaches the beginning of the message, the long marking signal is reproduced by the relay system as a long-spacing signal and contact 24 is open for a period of time sufficient to permit the release of the relay 23 which opens contact 38 in the circuit of the magnet 39, allows armature 27 to close its lower contact and at contact 25 closes a circuit for a clearing signal. At the end of the spacing signal the armature 41 returns to the mark position so that relay 23 energizes, moving armature 27 to the mark position and deenergizing the clutch magnet 19 prevents the magnet 17 from being energized except when the armature 41 is in the space position. Alarm arrangements. If the tape 4 between the heads 1 and 2 becomes taut, a roller 28 on the arm 8 is engaged by the tape so that the roller 7 is moved away from the roller 6 and the tape can be pulled through the head 1. If the tape between the heads 1, 2 is entangled, the arm 8 is raised farther and closes contacts 29, energizing a relay 45 which closes contacts 45 operating an alarm. Similarly, if the tape feed to the recording head 1 is obstructed, a pivoted arm 31 closes contacts 33 which also operate the alarm circuit. Apart from the case in which the signal elements are constituted by impulses of opposite polarities, the reproduced signals are erased by a wiping-out head 42, Fig. 1, fed with high-frequency current. Breaks in the tape are detected by conducting rollers 34, 35 effective in such a case to make contact with metal parts of the container and to energize relay 45 of the alarm circuit. Specifications 685,067 and 685,109, [Group XIX], are referred to.