Patent GB-952832-A (GB)
Title: Improvements relating to automatic telephone exchange systems
Inventor: LONG DOUGLAS PERCY
IPC: H04Q3/62
Filed: 1960-01-18
Abstract: 952,832. Automatic exchange systems. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Jan. 10, 1961 [Jan. 18, 1960], No. 1772/60. Heading H4K. In an exchange system wherein a call is set up in a stage by stage manner involving the successive taking into use of a plurality of ranks of uniselectors, a first selector is coupled to a register common to a plurality of first selectors, wherein the dialled digits are stored, and a further or final selector is coupled to a control circuit common to a plurality of further or final selectors, the control circuit in turn being coupled to a marker common to a plurality of such control circuits, the marker being set from the register by signals transmitted over the preceding selectors so as to apply a marking to the relevant outlet or group of outlets of the further or final selector. As described, the first selector switches consist of uniselectors having banks SW1 to SW8 (Fig. 1C) containing first and last contacts and fifty intermediate outlet contacts in a row, there being two rows per switch bank, which rows are swept by electrically connected but staggered wipers to give in effect one hundred and four contacts per bank; the rows are symbolically represented by full and dotted lines and the wipers are shown as single double. ended wipers. The final selector banks FW1 to FW6 (Fig. 4B) are similar in construction, banks FW7 to FW10 being of conventional single row type. A first selector common control circuit shown in Figs. 2A-2C comprises motor-driven uniselectors M, H, T, U which act as the register and a further uniselector SS which acts as a sequence switch for extending high or low resistance, plus or minus battery, over the register uniselectors to marking relays in a common marker circuit, Fig. 3. The latter relays effect marking, appropriate to the called number, in banks SW7 or SW8. A final selector common control circuit (Fig. 5) is taken into use with a final selector (Figs. 4A and 4B) and in turn seizes a marker (Figs. 6A, 6B) containing a number of marking relays operated in response to the aforementioned battery conditions extended over the sequence switch, so as to effect marking in banks FW7-FW10. Setting-up call; operation of first selector.- Upon the initiation of a call, a free first selector and its common control circuit are associated with the calling line and relay A, in the control circuit, pulls up to the calling loop. Release relay B and its slave BA follow thus busying the first selector and the control circuit. BA also allows coupling relay K to come up in series with R1, thus operating BB and lighting a supervisory lamp SL. In response to B, relay SC pulls up over wiper SS2 of the sequence switch and relay CD followed by CA also operates. Dialling tone is reverted over wire 38 and the pulses of the first digit dialled are repeated by relay A to step the thousands uniselector M, relay B holding throughout impulsing. During the interdigital pause CD releases, but before CA can drop out, magnet HDM is energized over wiper M2 so that as CA falls, the hundreds uniselector H is stepped on one step, thus allowing CD and CA to come up again. The hundreds, tens and units digits are then registered in the same way, CD finally releasing but before CA falls back, relay MF is energized over wiper U3 of the units uniselector. A wiper switching relay WS will now operate if the thousands digit dialled, caused wiper M6 of uniselector M to stop at a contact connected to wire 50. When the marker for this control circuit becomes free, relay MT is energized over its winding I and is followed by MG (in the marker) and MA (in the control circuit). MA completes the connection of the selector to the control circuit, completes at contact ma8 a test circuit for stopping the first selector on a last outlet in the event of an unsuccessful hunting operation, and causes, at contact ma4, uniselector SS to step once. This step initiates the release of SC by short-circuit over wiper SS2 but before SC finally releases a battery condition is passed over wipers SS3, SS4 to the marker in order to cause the operation of the marker relays. The battery conditions used for this purpose are (a) low resistance positive battery, (b) high resistance positive battery, (c) low resistance negative battery, and (d) high resistance negative battery. Thus condition (d) is shown, in Fig. 2B, in the connection of a contact of wiper bank H3 via wire 45 to resistor R6 and thence through resistor R5 to negative battery, while wire 57 connected to a single resistor R7 and positive battery indicates the use of condition (a) for marking a contact in wiper bank T3. One of these battery conditions is connected to each contact in the wiper banks H3, H4, T3, U4, which are associated with bank SS3 of the sequence switch, and one of these conditions is applied using R9-R12 to some of the contacts in the wiper banks H5, H6, T4, U5 associated with wiper SS4. In the marker (Fig. 3) either relay W or relay Y will always respond over SS3 when the sequence switch takes this first step and in the case of low resistance signalling, relay X or relay Z respectively will also come up. In response to W or Y, relays WA or YA will pull up to negative battery on a holding wire 49, and, when W or Y releases (to be explained) a start relay S operates in series with the operated one of relays WA and YA. Additionally relays V or Q may be energized over SS4 by high resistance negative or positive battery respectively and if low resistance signalling is used relay P also operates. The banks SW7 and SW8 of the first selector are thus marked. However, the release of SC de-energizes magnet SSDM and the sequence switch steps on once more, SC then pulling up again. The operation of start relay S in the marker when the operated relay W or Y releases causes an operating earth to be extended to the stepping magnet LM of the first selector, causing this to hunt for the marked contact in bank SW7 or SW8. If the appropriate final selector (Figs. 4A, 4B) and its associated control circuit are free (contacts bdl, be1 closed), negative battery via resistor R18 and closed, off-normal contact NN1 is extended over the P-wire 53 to bank SW5 (or SW6 if WS has operated), thence to SW7 (or SW8) and via the marking relay contacts to high-speed test relay TT which operates to stop the hunting action by inserting relay TA in series with magnet LM. Operation of TA causes HA to come up, MF to release and earth to be connected to a meter in lead 65. The falling back of MF releases the marker from the control circuit and the operation of HA closes an energizing circuit for relay SK (Fig. 2B). If the hundreds digit is such as to cause the operation of relay WSS (Fig. 4A), then only the low resistance winding I of SK will be energized in a circuit extending from earth via bank H7, over wiper SS3 and the negative line wire 51 to negative battery connected to relay WSS in the final selector (Fig. 4A), KK having operated on seizure of the final selector (see below), WSS and SK then operating in series. If the earth on bank H7 is not present, SK pulls up to negative battery connected to resistor R16 (Fig. 5) and WSS does not operate. In operating SK causes MC to pull up in series with line relay MM (Fig. 5) over the positive line wire thus readying the final selector. The aforementioned re-operation of SC allows a slow-releasing timing relay TU to operate (uniselector wiper SS5 on third contact). In the final selector common control circuit operation of MM leads to the operation of MAA (in a way to be explained) with subsequent release of MC in the first selector common control circuit and thus the energizing circuit of SSDM is opened and uniselector SS takes another step. One of the four already mentioned battery conditions is thus applied from the tens register uniselector via wiper SS3 and the negative line wire to a wire 55 in the marker which by now has been associated with the final selector in question and marking relays therein are therefore operated. A similar condition may also be signalled to wire 56 in the final selector marker over wiper SS4 and the positive line wire 52. Meanwhile SC completes its release (initiated by the last mentioned step of SS) and causes uniselector SS to step on to the fifth contact. Thus SC re-energizes but TU begins to release and when it does so (contact tul falling back) SS is stepped on again, and SC now begins to release once more. With the wipers of uniselector SS now standing on their sixth contacts, one of the battery conditions is applied over the units register uniselector and wiper SS3 (and possibly SS4) to the marking relays in the final selector marker (marker relays UU, VV, WW, YY, Fig. 6A, having released while the wipers of SS were on their fifth contacts) so as to complete the marking of the final selector switches. When SC finally releases SS is stepped on and relay FSW pulls up in series with the negative line and relay VV (Fig. 6A), the latter however remaining down. FSW re-energizes TU so as to prevent premature operation of relay XM (Fig. 1B). If the marked outlet in the final selector is tested free then contact t61 (Fig. 6A) opens and FSW is released followed by TU and subsequently XM operates. XM releases A and hence B and also releases the control circuit from the first selector and it brings up AA. Ringing.-Ringing current and ringing tone are supplied from the first selector and on the reply of the called party, ring-trip relay F operates to complete the connection, thus bringing up relay D which holds BB and hence F, HA and XM. Busy conditions.-If the first selector had found congestion when the wipers of sequence switch SS were standing on their third contacts or if the final selector found that the called line was busy (wipers of SS on seventh contact), a relay LC would pull up to an earth appearing on the last contact of positive wiper SW3 (or SW4) or F