Patent GB-811151-A (GB)
Title: Improvements in or relating to telephone exchange systems and apparatus
Inventor: BARNARD ARTHUR JOSEPH
IPC: H04M1/65
Filed: 1955-12-16
Abstract: 811,151. Automatic exchange systems. STANDARD TELEPHONES & CABLES Ltd. Dec. 16, 1955, No. 36153/55. Class 40 (4). Dictation equipment is connected as a substation line circuit; on receipt of a clearing signal from a calling subscriber, the calling substation is released by the removal of an engaged condition from the exchange switching equipment associated with the dictation equipment, which latter equipment is immediately re-engaged and held until it becomes available for further use. The Figures show one of a series of control units, each of which controls an associated sound-recording and reproducing apparatus over leads 1-7 and is connected as a line circuit to a group-selector outlet, the control units being available as a group from which a disengaged control unit can be automatically selected in the normal way. Calling subscriber dials number allocated to dictation equipment. A group selector hunts for and seizes an idle control unit at which relay A operates in known manner. This brings up relay B followed after a delay by relay BB, so that a loop is momentarily established between leads 3 and 6, the resulting pulse on lead 6 preparing the dictation equipment for operation. Relays B and BB, which remain operated for the duration of the connection, also connect busying earth to the P-wire of the control unit, start a tone-generator, and light a " busy " lamp. Warning tone is relayed to the calling subscriber over relay A and wiper S1 of a uniselector in the control unit. Caller dials digit " 1 " to start the recording apparatus. Relay A responds to dial impulses in the normal way and its relapse energizes relay C in series with switch magnet M which drives the uniselector wipers S1-S3 to their first position. Relay C brings up slow-releasing relay R. When relay A reoperates, C falls back and relay SR is energized over wiper S2. Relay SR completes a holding circuit for itself, disconnects the warning tone, stops the tone generator, puts a loop between leads 3 and 5 to prepare the apparatus for recording, and opens the loop on leads 3 and 4, causing the recording apparatus to start running forwards. Speech from the calling subscriber over leads 1 and 2 is then recorded. When relay R completes its delayed release, following the relapse of relay C, it opens the loop on leads 3 and 5 and completes a self-interrupting circuit for switch magnet M over wiper S3. The uniselector is thereby driven to its fifth position, which is the next " home " position, the bank contacts being arranged in groups of five as shown. Caller dials digit " 2 " to stop the recording apparatus. Relay A and magnet M respond to the dial impulses and the uniselector takes two steps forward. Relays C and R are operated and hold during the impulsing, releasing relay SR to restore the loop on leads 3 and 4, which stops the recording apparatus. When C and R have released, the uniselector is driven to its next home position. To resume dictation the calling subscriber dials " 1 " as before. Caller dials " 3 " to play back the last part of his recording. Relays A, C and R and magnet M respond as before, and the uniselector steps to its third position and later homes. During the release period of relay R, following the relapse of C, relay BS is energized over wiper S2. This maintains the loop on leads 3 and 4, ensures the disconnection of lead 5, establishes a loop on leads 3 and 6 to cause the recording apparatus to ruin backwards at high speed, and brings up relay SR which locks. When R finally falls back, BS follows slowly, breaking the loops between lead 3 and leads 4 and 6 so that the recording apparatus runs forward again. The calling subscriber hears the last part of his recording over leads 1 and 2. If the record has not gone back far enough, the caller may dial a succession of 3's to drive it back further. As before, dictation may be resumed following the dialling of " 1." Caller dials " 4 " to call attendant. In this case the uniselector takes four steps and the relapse of relay C completes a circuit over wiper S2 for relay O, which locks itself operated and energizes a calling lamp and buzzer. When the uniselector goes home, the tone generator is started and the callerreceives ringing tone over relay A. The attendant at the dictation equipment answers by plugging a telephone set into a jack shown in the upper right-hand corner of Fig. 3, operating relay D. This releases relay O, disconnecting the calling lamp and buzzer and the ringing tone lead, and stops the tone generator. The attendant is then in communication with the calling subscriber. Recording medium nearly full. When a device, such as a metal insert, in the recording medium passes a predetermined point, a pulse is sent over lead 7to the control unit, bringing up relay O which sends ringing tone to the calling subscriber and calls the attendant as described above. Calling subscriber hangs up. Relay A falls back, followed by B which removes busying earth from the P-wire to release the caller and brings up relay O to call the attendant. Relay BB releases slowly after B, replacing busying earth on the P-wire and extinguishing the " busy "lamp. These conditions are maintained until the attendant removes the used recording medium, when a spool switch closes to energize relay D. This maintains busying earth on the P-wire, stops the tone generator, disconnects the warning tone lead, and releases relay 0 which disconnects the calling lamp and buzzer. When a fresh recording medium is inserted, the opening of the spool switch releases relay D to restore " line free" conditions. A manual switch in parallel with the spool switch enables relay D to be operated and the control unit busied at will. Reference has been directedby the Comptroller to Specification 747,425.