US2416109A

US2416109A - Rotary type selector switch for automatic telephone systems

Info

Publication number: US2416109A
Application number: US640260A
Authority: US
Inventors: Long Douglas Percy
Original assignee: Siemens Brothers and Co Ltd
Current assignee: Siemens Brothers and Co Ltd
Priority date: 1945-01-01
Filing date: 1946-01-10
Publication date: 1947-02-18
Anticipated expiration: 1964-02-18
Also published as: GB578984A

Description

Feb. 18, 1947. LONG 2,416,109

- ROTARY TYPE SELECTOR swITcH FOR AUTOMATIC TELEPHONE SYSTE'MS.

Filed Jan. 10, 1946' a &

INTERM/TTENT 84 771R) I E AITH D H" v DOUGLAS PERCY LONG Patented Feb. 18, 1947 2,416,1091] I k ROTARY TYPE SELECTOR SWITCH FOR AUTOMATIC TELEPHONE SYSTEMS Douglas Percy Long, Chislehurst, England, assignor to Siemens Brothers & Co. Limited, London, England, a British company Application January 10, 194.6, Serial No. 640,260

.In Great Britain January 1, 1945 This invention relates to automatic telephone systems and more particularly to the control of selecting switches required to search in a group of outlets in accordance with a markingap to their contact banks consequent on the receipt of a train of impulses. It has in view improved means for the control of a single motion selecting 9 Claims. (Cl. 179-18) switch by apparatus individual to the switch and using the minimum of control apparatus.

In a single motion selecting switch having a large number of outlets wiper switching may be employed whereby the switch is constrained to search in one or other of two sets of banks. As the time available for searching is limited by what is known as the inter-train pause the number of consecutive bank contacts which can be tested within that period of time is dependent on the speed of operation of the switch. Owing to this limitation and the necessity for avoiding complicated or uneconomical wiper switching arrangements, arrangements have been proposed in. which an increase in the number of outlets may be had by adapting the wipers to sweep two banks in succession, hereinafter termed a pair, and for search in the second of the .two banks a preliminary setting is given to the wipers at thetime the selecting switch is taken into use.

This may be efiected dependent on the path of entry to the selecting switch or other discriminating action such as a signal,v from a preceding switching stage. The selecting switch may be taken into use in response to either of a pair of digital values received at a preceding switching stage, the discriminating action serving to dis tinguish between the two digital values of'the pair. Outlets corresponding to one such value would then be accommodated in one of the two banks of the pair and outlets corresponding to the other of such digital values would be accommodated in the other of the said two banks. In addition,a further discriminating action may be had by wiper switching in accordance with the digital value actually received at the selecting switch.

In the present invention it is arranged that the stopping circuit for the selecting switch is deimpulses may be received in the switch circuit and in accordance with the usual practice the dialling relay is operated prior to receipt of the switch setting train. In its operated condition the diallingrelay connects the test relay in a circuit in which the operation of the latter depends on a wiperreaching the contact in the selecting switch bank at the desired preliminary position. The selecting switch has therefore to move to its preliminary position before the diallingrelay releases at the end of the impulse train; This is ensured without imposing limitations on the disposition of the outlet by employing a high speed selecting switch and a dialling relay with a release lag long enoughto extend over the preliminary setting period even if only a single impulse has been received. In the other condition of the dialling relay the test relay should be connected to the test wipers in the normal manner.

The discriminating action is conveniently effected by a relay which is operated or not at the I time the selecting switch is taken into use and pendent on the condition of the dialling relay 'which is usually provided to determine the end of an impulse train. In one condition of this relay the selecting switch may move to take up a'preliminary position adjacent to aset of outlet groups in response to a. discriminationefiected at the' ror wiper switching purposes. 4 with mid-normal contacts on the selecting switch which, in one condition initiates the preliminary movement of the selecting switch. A suitable relay for the purpose is the wiper switching relay leased prior to the time at which itsoperation may be required for wiper switching purposes, the circuit for the continued driving of the selecting switch beingmaintained by other means after the release of the wiper switching relay. The discriminatin'g action may be brought about by means of a signal f'roma preceding circuit. The signal may conveniently take the form of an absence of potential onone of the line wires at the time of switching through whereby the relay isallowed to operate in'a loop circuit to initiat the preliminary movement of the selecting switch. On the other hand, if no signal is to be transmitted a suitable potential is applied to the said line wire to prevent operation of the relay.

While the contacts in the selecting switch bank on which the switch is to stop in its preliminary movement may be marked directly the outlets to besearched will be marked in a circuit including a contact of a marking device and a back contact of the dialling relay. The marking device may take the form of a stepping switch responsive to 'digits'and suitably connected contacts may serve for the operation of thewiper switching relay In conjunction .5 switch is stepped in accordance with the impulses received. Relay C is held in this circuit during impulse reception. When the digit switch is stepped from its normal position the oif-normal contacts are operated. Contact DONI opens the operating circuit for relay C over its upper winding and contact DONZ prepares a selfstepping circuit for the digit switch for homing it. At the end of the impulse train relay C releases and at contact closes a circuit for magnet MU and at contact 06 connects earth to the contacts of the group in the marking bank of the selector corresponding to the received impulses. Contact 03 connects the test relay T over contacts b3 and ws3 to the test wiper P and contact 01 opens a further point in the circuit for magnet DM over the lower winding of relay C. Magnet MU operates in a circuit from earth over contacts b5, DONI, 05, H, hi, the, magnet winding to battery and the wipers of the selector are rotated in search of a free outlet in the group marked in accordance with the received digit. Contact ON! disconnects the battery from wire p while the selector is off-normal Y portion, and over wiper M4 for the Z portion.

As for the moment consideration is only being given to the operation for selection in the W and Y portions of the bank the marking will be applied over wiper MI and if search is to be made in the Y portion relay WS will be operated in a circuit from earth over contact bl, MNI, wiper M3, the right-hand Winding of the relay to bat.- tery. When the selector Wipers are rotated on to contacts in the wanted outlet oup earth over contacts 06 wiper MI and marking wipers GI or G2 as the case may be, contact ws l and rectifiier MRA will be extended to the right hand winding of relay T and when a free outlet in the group is encountered, denoted by the presence of battery potential on the test wire, relay T will operate over the above traced circuit from earth and over its left-hand winding and contacts 03, b3, ws3 wiper P to the battery potential on the test wire. Contact H at its back contacts opens the operating circuit for magnet MU and removes a short circuit from relay H, and at its front contact short-circuits the right hand winding of relay T and earths the test wiper over the low resistance left-hand winding of relay T to engage the outlet. Relay H operates from earth over contacts 0N2, 04, b4 and the winding of magnet MU. The magnet will not hold in series with relay H and the rotation of the switch wipers is stopped with the wipers on the contacts of the free outlet. Contact hi opens a further point in the operating circuit for magnet MU, contacts h2, h3, b4 and b5 switch through the speaking and test wires and contact h8 opens a further point in the circuit for magnet DM. The extension of earth over wire 10 and contacts M and 72.5 short circuits relay T which thereupon releases. At contact 712 relay A is released and by the falling back of contact a! relay B releases. Relay H remains held to earth on the test Wire applied in the succeeding switch consequent on the operation of the release relay therein. Contact 193 disconnects the circuit for relay T, contact 134 opens to leave relay H dependent on the earth fed back over the test wire, contact b5 opens in the op erating circuit for relay C and contact b6 closes in the homing circuit for the digit switch. If no discriminating signal is to be transmitted from the selector the contact in the bank of wiper M1 corresponding to the impulses received will be connected over contact cl to the positive speaking wire and at the time the succeeding selector is taken into use the impulse receiving relay therein will operate over a preceding loop to earth over the positive wire, contact cl, wiper M1 and contact b2. The wiper switching relay in the succeeding switch will be shunted by this connection and will not operate. If, however, a discriminating signal is to be transmitted there will be no connection to contact cl from the bank of wiper M1 and relay WS in the succeeding switch will be included in the loop circuit over which the impulse relay operates. The release of relay B will disconnect the shunting earth, if it has been applied, by which time the succeeding selector will have moved oil,- normal with the consequence to be described later.

It will now be assumed that at the time the selector shown in the drawing is taken into use a discriminating signal is received and relay WS is operated in the manner above described. The early closure of contact ws5 closes a circuit, over contacts 05, ii, and hi for magnet MU and the selector is set in motion. As soon as the selector wipers move from their normal position contacts ONI and 0N2 are operated and the latter close a circuit for magnet MU that is independent of contacts ws5 and 05. In the meantime relay A has operated and operated relay B and a circuit has been closed over the upper winding of relay C, but by this time the selector has moved off normal and the circuit for magnet MU rendered independent of relay C. Contact b2 on closure short circuits relay WS to release it. When relay C operates relay T is connected over contact 03 to battery over resistance YA and the selector will continue in operation, contact c6 being open, until the wipers have made atraverse of the W and Y portions of the bank. When wipers GI and G2 reach the first contacts in the X and Z portions of the marking bank a circuit for-relay T will be provided over an earth connection to these contacts and the selector will be brought to rest. The release lag of relay C is arranged to'cover the period required for this rotation of the selector wipers, even if only one impulse has been received in the selecting digit, so that at the time of operation of relay T contact 04 will be open and relay H will not be operated. In this position of the selector wipers contacts MNI and MN2 are operated. After the end of the impulse train relay C will release and by this time relay WS will have been released. Contact 03 will open the circuit for relay T, releasing it, and with contact 05 closed magnet MU will again operat and the selector wipers will be driven over the X and Z portions of the bank. When the contacts of the outlet group marked over wiper M2, since the X and Z portions of the bank are concerned this time, are encountered-the circuit for the test relay is connected up and the individualoutlets of th group are tested over wiper P in the manner before described and when a free outlet is met relays T and H are opwipers. will be without useful efiect.

I contacts, N2.

I priate to selection in the W and X portions of j the bank. If selection is to be made in the Y or Z portions the impulses received by the digit switch will be such that wiper M3 or M4 as the case may be will be connected to relay WS and on the coming to rest of the digit switch at the end of the impulse train relay WS will be operated and by means of its contacts wet-ava l the 1 connection to the selector wipers will be changed over from the W and X wipe-rs to the Y and Z The closure of contact 1035 at this time If, during the search for a free outlet none is encountered in the marked outlet group the selector wipers continue to advance until the last contacts in that portion of the bank in which the selector in that position, the circuit being completed over the appropriate test wiper P and the shunted upper winding of relay C. Relay C 1 operates in series with the test relay after its delay period during-which relay H is operated.

At contacts c2 and he a source of busy tone I is connected over the right hand winding of relay A and by induction into the middle winding is transferred over the last contacts in the several portions of the bank and wipers to the callers line, the return path being over the negative wiper and the left-hand winding of relay A. At

1 the same time intermittent battery and earth are applied over the middle winding of relay A i to give a flashing signal in known manner. During the period when battery is connected to all the windings of relay A the relay is held over its right hand winding and contacts hfi and 02 to earth in the tone circuit. Earth on'wire in over contacts h l, b4, ed, M, MNZ, and one of the wipers M5 and M6 operates an overflow meter.

When the caller clears at the end of a con- .versation or on receipt of busytone earth is disconnected from the test wire, either at the circuit from which the connection is held or by the re- 3 lease of relay A in an interval during which earth is connected over its middle winding followed by release of relay B. Relay H releases and recloses the circuit for magnet MU at contact hl and the selector wipers are driven to their home 1 position in which they are stopped by the deenergization of magnet MU on the opening of Closure of contact h8 completes a homing circuit for the digit switch over contacts al, DONZ, clm and b6 and the digit switch is restored to normal. With the digit switch and the selecting switch both at normal battery is again connected over resistance YA to wire p to enable the selector to be taken into use for an- 1 other call. with relay H.

Relay WS, if operated, is released What I claim as new and desire tosecure by 1 Letters Patent is:

1. In an automatic telephone system, a single the operation of said selector, a transfer relay operated during the said train of impulses'and;

freleased after the completion thereof means, in-

a searching movementfollowing such release to select. any desired one of said outletv groups and an idle outlet therein, means independent of said marker for starting said selector at times in a preliminary movement prior to such release, and means for controlling the extent of each of said movements dependent on the condition of 'one of said marking positions in response to a train of impulses to cause said selector to hunt an idle outlet in either of said groups of outlets depending on its starting position, a transfer relay, means for operating said relay during the said preliminary operation and releasing it prior to the said outlet hunting operation, a stopping circuit prepared by said relay in its operated condition for stopping the preliminary operation of said selector when said second starting position is reached, and a second stopping circuit prepared by said relay in its released condition for stopping the outlet hunting operation of said selector when an idle outlet is reached in the selected group of outlets.

3. In an automatic telephone system, a single motion selector, first and second main groups of outlets accessible to said selector, sub-groups in each of said main groups, first and second starting positions for said selector, means responsive to a single train of dial impulses for causing said selector to select a desired sub-group of outlets in either of said main groups depending on the starting position of said selector, said selector then acting automatically to select an idle outlet in said selected sub-group, a pair of line conductors incoming to said selector, a selector line relay connected to one of said conductors, a selector starting-position relay connected to the other of said conductors, means for operating both of said relays in series over said line conductors upon seizure of the selector whenever it is desired to select an outlet in said second group of outlets, and means operated in response to such operation of said starting-position and line relays for driving said selector to said second starting position.

4. In a rotary type selector for use in an automatic telephone system, a set of contact banks and wipers, first and second main groups of outlets connected to said contact banks, sub-groups in each of said main groups, first and second starting positions for said wipers. a marker operated responsive to a single dialled digit for causing said selector to select any of said subgroups and an idle outlet therein in either of said main groups of outlets depending on the starting position of said wipers, a second set of contact banks and wipers, other outlet groups similarly connected to said second set of contact banks, a wiper switching relay, contacts on said relay for selecting either of said wiper sets, said relay being operated momentarily upon seizure of the selector in case the wanted group is in a second main group of outlets, means operated in response to such preliminary operation of said .relayto cause the wipers to advance to their sec-- ond starting position, and means for operating and holding said relay in response to the dialled group selecting digit to select said second set of wipers in case the wanted outlet group is connected to said second set of contact banks.

5. In a telephone system, a rotary type selector, contact banks for saidselector, a first and a second main group of outlets, sub-groups in each of said main groups, a marker, said marker being set in response to a dialled digit to mark a sub-group in each of said main groups for selection, a transfer relay operated during the setting of said marker and released after such setting to cause said selector to select one of said marked subgroups and an idle outlet therein, a marking bank for said switch for marking said subgroups for selection in accordance with the setting of said marker, a first and a second starting position for said selector, a first and a second start contact for said marking bank, a permanent marking for said second start contact in said marking bank, means for causing said selector to advance in a preliminary movement upon seizure in case it is desired to select a sub-group in said second group of outlets, means for operating said transfer relay also during said preliminary movement, and a stopping circuit including said permanently marked second start contact and front contacts on said operated transfer relay for arresting said preliminary movement and stopping said selector in its second starting position.

6. In an automatic telephone system, a rotary type selector switch, contact banks and wipers for said switch, two main groups of outlets connected to said banks, sub-groups of outlets in each of said main groups, first and second starting positions for said wipers, a pair of speech conductors incoming to said switch, a pulsing relay normally connected to one of said conductors. a discriminating relay normally connected to the other of said conductors, means for momentarily operating said discriminating relay in series with said pulsingrelay upon seizure of said selector to advance said wipers away from their first starting position in case it is desired to select'a sub-group of outlets in said second main group, off-normal contacts on said switch for maintaining said advance independently of said discriminating relay, a stopping relay for said switch, back contacts on said stopping relay in series with said off-normal contacts, means for operating said stopping relay and opening said back contacts to stop said advance and said wipers in said second starting position, and impulse responsive means operated under the control of said pulsing relay in response to a single dialled digit for causing said wipers to select a particular group of outlets in either of said main groups depending on the starting position of said wipers.

7. In a telephone system, a single motion selector switch, wipers for said switch, two main groups of outlets accessible to said Wipers, a normal and a second starting position for said Wipers, means for causing said wipers to select an idle outlet in either of said main groups of outlets depending on the starting position of said wipers, a pair of conductors incoming to said switch, a relay normally connected to one of said conductors, means for momentarily operating said relay upon seizure of said switch whenever the second group of outlets is wanted, a start circuit completed responsive to said relay operation for advancing said wipers away from their normal starting position, oif-normal contacts operated when said wipers leave said normal starting position for continuing said advance independently of said start circuit, means for stop- D said Wipers automatically at said second starting position, and front and back contacts reversed by said switch in each of said normal and second starting positions to cause different operations upon the completionof the selection of an idle outlet, depending on which of said main groups of outlets is involved in said selection.

8. In an automatic telephone system, a rotary type selector, a first and a second set of wipers for said selector, a first and a second main group of outlets respectively accessible to each of said sets of wipers, sub-groups in each of said main groups, a normal and a second starting position for said wipers, a marker switch for said selector operated'by dial pulses, means for causing the wipers of said selector to select an idle outlet in one of said sub-groups in either of said main groups depending on the starting position of said wipers and the operated position of said marker switch, a wiper switching relay, means for causing a preliminary operation of said relay upon seizure of said selector, means operated responsive to the said preliminary operation to advance said selector from its normal to its second starting position, a pair of wiper-switching contact banks for said. marker switch, midnormal contacts reversed by said selector in its second starting position, means for again operating said wiper switching relay through either of said wiper-switching contact banks depending on the position of said midnormal contacts in case it is desired to select an outlet accessible only to said second set of selector wipers, and contacts operated by said wiper switching relay to cause such selection to occur through said second set of selector wipers.

9. In an automatic telephone system, a rotary type selector, speech conductors incoming to said selector, a first and a second rank of bank contacts for said selector and a first and a" second main group of outlets connected respectively thereto, sub-groups in each of said main groups, a normal and a second startin position for said selector; a marker switch operated responsive to a dialled digit to cause said selector to select an idle outlet in either of said main groups and,

depending on the digit dialled, in any one of the sub-groups therein; discriminating means operated upon seizure of said selector for causing said selector to advance from its normal starting position to its second starting position preliminary to its outlet selecting operation in case the desired outlet is in said second main group of outlets, a transfer relay operated during the dial pulses and released at their conclusion to initiate theoutlet selecting operation, a switching relay operated upon the selection of an idle outlet to extend said speech conductors to such selected outlet, means for advancing said selector to the last contact of the rank of contacts over which it is searching in case no idle outlet is available in the selected sub-group, and means for operating said switching relay and re-operating said transfer relay when the said last contact is DOUGLAS PERCY LONG.