Patent GB-289928-A (GB)
Title: Improvements in automatic telephone systems
IPC: H04Q3/42
Filed: 1927-01-31
Abstract: 289,928. Siemens Bros. & Co., Ltd., Christian, D. A., and Humphries, 3M. E. Jan. 31, 1927. Addition to 265,732. Semi-automatic exchange systems.- In a system in which an A ' operator sets up a call over a junction by means of a decoder-sender, which she controls by a key-set associated with her cord circuit, as in the parent Specification, each free decoder-sender is maintained in connection with a free junction, and is taken unto use over a decoder-seeker, the number of the associated junction being indicated to the operator. The operator initiates the seizure of a sender by either pressing a key individual to the group of junctions desired, touching the sleeve of or plugging into a special jack, or touching an isolated portion of a stile strip with the plug to be used. This operation starts the operator's seeker and also marks a level thereof so that it only hunts for junctions to the required exchange. If all the junctions of a group are busy, the seeker starting circuit is held open. The junction-finder individual to a sender is a two-motion switch, having two single-motion wipers, vertical and rotary, which are so connected that by their positions in the banks, combinations of relays are operated to put potential on certain leads to the seeker, over the wipers of which groups of tens and units relays are variously operated to light lamps indicating the junction. The finder has rotary and full release magnets and hunts over consecutive levels in turn until, if no idle junction is found, the top level is finished, when the switch returns to normal and re-commences hunting. Instead of the intermediate relays operated over the finder for indicating the associated junction, the codes may be transmitted over early contacts of the in-controller IC of the sender, the control circuits thereof changing when the operator plugs in. After plugging into the indicated junction, the operator taps the required number on her key-set, so that varying potentials are put on the a and b wires to operate variously hundreds, tens and units relay groups in the sender, the groups having flutter circuits terminated, in different ways, by the particular potential applied. Seizure and indication of available junction. On receipt of a call, the operator presses key OWK, Fig. 2, to earth lines rs, ps, to the indicator relay group, Fig. 3, and the decoder-seeker DS, Fig. 4, operating relay L. If the seeker is on the contacts of a busy sender, self-interrupting magnet DM operates over wiper F1 to earth at sr7, Fig. 7, to find an idle sender, when relay T, Fig. 4. energizes in series with relay CT, Fig. 5, over F1, cutting out magnet DM. The vertical wiper V of the sender, Fig. 7, is standing on the level corresponding to the tens digit of the number of the asscciated junction, while the rotary wiper E stands on the contact corresponding to the units digit. Earth over armature ct2, and wiper V, energizes the appropriate marking relay of the group CTR to earth one or more of the wires aa - dd to the indicator relay group CRR, Fig. 3. One or more of relays WT - - ZT is thereby energized in series with relay CR, Fig. 5, and locks up to wire rs, and the appropriate tens lamp LT lighted. Relay FR operates [earth, d1, cr1, er3, FR batteryl, opens at fr2 the circuit over wiper V, releasing the CTR relays and also CR. Relay ER now energizes over ct1, cr1, fr1, and locks up over er1. Relay B, Fig. 3, operates to earth at er2, to switch from the tens to units recording relays WU - - ZU, relay FR is held over er3, and the appropriate relays CTR energize over wiper E, and relay CR pulls up in series with the appropriate relays of group CRR to light the units lamp. Relay FR is released at cr1, and in turn releases the CTR relays. On noting the number, the operator releases key OWK, so releasing the CRR relays and L, which in turn releases relays T, CT, ER, B. All junctions in a group busy. If all the junctions are busy, even though there may be idle senders, a group relay GP, Fig. 4, is operated to prevent rotation of the seeker. Operation of junction-finder. Assuming that the two-motion hunting switch, Fig. 7, is off the banks and at its lowest point, relay VR energizes over normal contact k3, so that the vertical magnet VM operates over wire 19, so that the wipers take one step, releasing VR and the magnet in turn. Relay RR now operates from battery at sr2 to earth at key K, and re-energizes relay VR over its left-hand winding, so that the rotary magnet energizes over its interrupting contact rm, and steps the wipers around the level. If there is no free junction, relay PS, connected to the last contacts of all the junction levels except the last, operates over wiper C, relays SR (1), JT to earth over wire 20, relay JT also operating to open the circuits of VM, RR, VR. Relay PS is held over its winding 2 in ser-es with relay PT which pulls up to earth at rotary offnormal contact w1. JT is released at pt2 and the rotary release magnet MM1 energizes. On the restoration of w1, PT de-energizes but PS is held during its release over pt1, w1, after which PS. and MM1 de-energize. During the release period of PS, relay VR, operates over its winding 1 to earth at key K, closing a circuit for magnet VM to step the switch to the next level. PS. VR release in turn, and then RR, VR operate as before and search over the next level takes place. If all the junctions are busy, relays X (1) JT energize in series over the last contact in the final level stopping the drive, and relays RR, VR, JT are released by relay X. Relay X (2) locks up to earth at w1 and k2 in turn and the full release magnet MM energizes to return the switch to normal when hunting again begins. If a free junction is found, relays SA (1), Fig. 6, and JT operate in series over wiper C and SR (1). SA connects the tip and ring of jack JJ to wipers A, B, disconnects the jack from the junction, and closes the outward impulsing circuit over wiper D. JT stops the drive, connects earth over its low resistance winding 1 to wiper C to busy the junction, and release relays VR, RR. The windings of relay SR are now differentially connected to wiper C, and do not operate. Seizure of junction. The operator throws her speaking key and taps the sleeve of the indicated junction, and if it has not been seized at that moment by another operator, she will plug in. Relays S, Fig. 6, CS, Fig. 2, operate in series,. lighting lamp CSL, and at s3 putting low resistance earth over SA (2) on wiper C, so that differential relay SR operates over its winding 2 and locks up over both windings in series, putting out relay JT at sr1. Busy tone BS is now connected from the sender, Fig. 8, over wire 17 to wiper C; relay CT, Fig. 5, is de-energized and wire ff earthed. Registration of digits. Relay D, Fig. 8, operates over 13, 24, a, wiper A, operator's cord, key SK, to earth at the operator's receiver. Relay E operates over d1 and wire 13, locks up and releases D, connecting wiper A to the in-controller wiper 31. Wiper B is connected over e3 to relay J and wiper 32. In-controller magnet ICM operates over n3, e6 to step it to the first contacts, removing a short over wiper 34 from relay N which energizes, locks up and releases ICM at n3 and operates relays HE, TE, UE over n1. These relays lock up at their armatures he1, te1, ue1, removing a short over z4 from relay Z which operates. The interrupter motor, if not running continuously, is started over nt. Assuming the number to be 258, repression of key 2, Fig. 2, operates relay R, and earths the a and b wires over a high resistance and directly respectively. Relay J, Fig. 3, energizes over the b wire, and winding HE (2) in parallel therewith opposes winding HE (1) to de-energize the relay. Contact j1 connects earth over wiper 33 to HC (1), HA (1) in series; HC, HA do not operate fully, but buzz their contacts hc1, ha1, until HA pulls up over wire a, de-energizing HC, and locking up over wire 15. Relay J energizes relay JA, and when the key 2 is released, ICM operates from battery over ja 2 owing to slow-release effect of short-circuited winding JA (1) to step IC to its second contacts. Connection is now established from the third contact of wiper 41 of the outcontroller OC, CA (1), he2, ha4, hb2, to the second contact of wiper 51 of counter switch SS. Operation of key 5 earths the b wire only, energizing relay J, and buzzing TA, TO which do not fully operate. Current flows in winding 2 of relay TE in opposition to its winding 1 so that the relay releases. Relay JA again operates and when the key is released, ICM steps its wipers to the third contacts. On pressing key 8, relay P operates and earth over high resistance is connected to the b wire, and battery over low resistance to the a wire. Relays J, JA operate but UE is not released. Relays UA, UC buzz, but battery on the a wire energizes UC, cutting out UA, and operating UD in parallel, UC, UD locking over windings 2. Contact 8 of wiper 51 is now marked from OC over winding CC (1). On release, IC steps to fourth contacts. Impulse transmission. With 1C on its second contacts relay ST operates (wiper 34, ST, wire 14), connecting earth over st1 to relay A which is impulsed by slow interrupter I<1>. Contact a2 impulses the out-controller magnet OCM, but the pulse wire d is maintained closed at c1. OC is stepped to its third contacts when relay C operates [wire 14, a2, C (1), wiper 43, ca2], and locks up, so that magnet OCM is cut out, and impulses are sent over wire d, magnet SSM being also impulsed in series with C (2) to step the counter switch for each impulse sent out. When two impulses have been sent, relay CA operates over wipers 51, 41 and contacts of the hundreds relays, and lock ups, cutting out relay C. Switch SS is now homed by quick interrupter I<2>, OC is stepped round by relay A until the second contacts are reached when C energizes