Patent GB-747425-A (GB)
Title: Improvements in or relating to recording systems
Inventor: BALMER STANLEY
IPC: H04M11/10
Filed: 1953-08-18
Abstract: 747,425. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. May 18, 1954 [Aug. 18, 1953], No. 22690/53. Class 40 (4). Recording means at the exchange can be used by subscribers, play-back of signals recorded by one subscriber not being available to any other subscriber. Seizing recorder. When the subscriber dials the appropriate code his line circuit is extended to a recording set connecting circuit to energize A which operates B and lights lamp LP1. B busies the connecting circuit and energizes Z to cause the recording apparatus to run in a forward direction. A tone of the order of 10 kc/s. is prerecorded on the tape and erased immediately in front of the recording head so that this tone appears wherever there is no message. This tone is, therefore, received on leads RL, amplified, and applied to the subscriber's speech conductors and also over leads VL through band-pass filter FC to increase the current through the left-hand side of tube V1, so operating F. F operates S slowly to release Z and stop the recorder. The signal therefore disappears so that F falls back. A tone from lead 10 is then returned to the subscriber to indicate that a recorder has been seized. Recording message. The subscriber then depresses key K1 momentarily to operate Q, which restores S, so energizing X and disconnecting tone. X starts the recorder to record speech from the subscriber. Operation of key K2 operates P, which releases Q and X to stop the.recorder and return tone to the subscriber again. By holding down key K3 the subscriber energizes both P and Q to energize Y which reverses the tape quickly, so producing a noise in the subscriber's receiver. P and Q also energize G slowly. Rewinding of the tape past the beginning of the message is prevented by the 10 kc/s. signal again operating F which energizes S to release Y to stop the tape. Release of key K3 restores P, Q and G, and Z pulls up to play back the message. At the end of the play-back the pre-recorded 10 kc/s. signal stops the tape again. Exhaustion of tape. When the record tape is getting near its end terminals TC are bridged for a short time so that valve VI operates F and T to return a warning tone from lead 11 and energize TF which lights lamp LP2 and busies the recorder against seizure when the subscriber releases it. At the end of the tape F and T operate long enough to energize S, Z releases and the recorder is stopped. If the subscriber then hangs up A releases B slowly and E pulls up, lamp LP1 extinguishing. TF maintains earth on the P wire. Release of B restores E and operates alarm BA and lamp LP3 to indicate exhaustion of the tape. F, T, S, TF remain operated until the attendant depresses key K6 and replaces the tape. Normal release by subscriber. If the subscriber has been playing back his record and hangs up after releasing key K3 but before exhausting the recording tape, Z holds up until B releases or S operates. The slow-operate period of S ensures a sufficient 10 kc/s. signal being impressed on the tape between recordings to prevent another subscriber reversing the tape sufficiently to hear the previous recording. Assistance by attendant. If the subscriber requires information or assistance from the attendant he dials a further digit. A releases at each impulse but B remains operated. Therefore E pulls up to energize alarm BA and light lamp LP3. The attendant's jack depresses key K5 to release E, BA, LP3 and she answers over leads AC. Breakage of tape. If the tape breaks the rollers shunt terminals TC to operate F, T, TF to operate the alarm as for exhaustion of recording material.