Patent GB-782883-A (GB)
Title: Automatic dialing mechanism for a telephone system of the automatic exchange type
Inventor: SEIDEL WILLY
IPC: H04M1/274
Filed: 1956-01-20
Abstract: 782,883. Automatic exchange systems. DEUTSCHE TELEPHONWERKE UND KABELINDUSTRIE AKT.-GES. Jan. 20, 1956, No. 2084/56. Class 40 (4). To facilitate calls to frequently-wanted subscribers, automatic impulsing equipment is arranged to transmit impulse trains corresponding to the wanted number in response to the reception of a single digit (or two digits) dialled by a calling subscriber, the equipment being available to any one of a group of subscribers. To make use of the equipment, a calling subscriber TN1 operates a key ET without lifting his receiver from its switch-hook HU. A relay U1 responds, switches in the automatic impulsing equipment, and brings up a relay T1, which indicates that TN1 is the calling subscriber and connects a relay A to the dial impulsing contact nsi. Relay T1 connects a particular pair of wipers (in this case wipers 5 and 6 of switch JW1, corresponding to the calling subscriber TN 1) of two switches JW1, JW2 to the contacts of bank ew1 in a switch EW over leads AGJW1 or AGJW2. (If relay T4, T5 or T6 is energized, relay GR operates with it to connect up switch magnet MJW2 in place of MJW1.) When the calling subscriber releases his key ET, relay A is energized, completing a circuit over wiper ew3 for relay BE which lights the subscribers' busy lamps BL and brings up relay X. Relay U1 holds on its winding II. The calling subscriber now dials the digit allotted to the wanted subscriber, and relay A repeats the impulses to magnet MEW which steps wipers ew-ew4 accordingly. The first relapse of A brings up a slow-releasing relay V which holds until the end of the impulse train when it falls back to complete a circuit over wiper ew3 for relay AN which releases relay BE. (If the calling subscriber wishes to cancel the dialled digit, he re-actuates key ET to release relays An, AN and X and briefly energize relay A1 which releases relays U1 and T1. Magnet MEW and relay CO interact to drive the switch EW to its rest position where wiper ew4 breaks the circuit for MEW.) The operation of relay AN completes a self-interrupting circuit for magnet MJW1 which drives switch JW1 until t reaches the position marked over one of the leads RR by wiper ew2, in this case the first contact of group KK1, where relay D operates to stop the switch. Relay J by self-interruption now produces impulses which are sent over the calling loop to the exchange, relay V being energized during the impulse train. A counting chain of relays CA to CE follows the impulses, relay CO being operated for impulses 1-5 and relay Y for impulses 6-10, so that the wires 1-0 of a distributer KK are connected in turn to winding I of relay P. This continues until the wire (corresponding to the first digit to be sent) connected to the first contact of group KK1 is reached. Relay P then operates over wipers JW1 and ew1, disconnecting the impulsing relay J and releasing the counting chain. Its winding II makes P slow-releasing, to provide an interdigital pause. With the cessation of impulsing, relay V falls back, energizing magnet MJW1 which is subsequently de-energized by the relapse of P. Thus switch JW1 steps on to the second contact of group KK1, which is connected to the wire of distributer KK corresponding to the second digit to be sent. Relay J resumes its impulsing for the second digit, and so on. When all the digits have been sent, switch JW1 steps off the contact group KK1, releasing relay D which energizes relay RU. This connects up A.C. to ring the calling subscriber's bell, starts heating a thermal relay TH2, and releases relay A followed by relays AN and X. The busy lamps BL are extinguished and a homing circuit for switch magnet MJW1 is established over off-normal contact jwlw. When the calling subscriber lifts his receiver, or when thermal relay TH2 completes its operation, relay A1 operates on winding I or II respectively and initiates release of the automatic impulsing equipment by releasing relays RU and U1, the latter switching the calling line through to the exchange so that the call proceeds normally. Release of the equipment is also initiated by the operation of relay A1 if switch JW1 or JW2 reaches its final position, winding III of Al being energized, or if the calling subscriber fails to dial, a thermal relay TH1 then being operated over wiper ew3 in its rest position. If the calling subscriber lifts his receiver during impulse transmission, he can follow its progress by means of signals induced in a coil LII from a coil LI. Specification 300,497, [Class 40 (iv)], is referred to.