US2170899A - Telephone system - Google Patents

Description

Allg 29, 1939- H. E. HUMPHRlEs ET AL 2,170,899

TELEPHONE SYSTEM Filed March ll. 1957 I I'I CMQ DG m0 Patented Aug. 29, 1939 UNITED STATES PATENT OFFIQE.

'rELErnoNE SYSTEM land Application March 11, i937, Serial No. 130,390 In Great Britain March 20, 1936 11 Claims.

The present invention relates to telephone systems and more particularly to systems in which connections are set up by operators. It concerns mainly arrangements for signalling to an operator the condition of a group of junctions or trunks and enables an indication to be given in a manner Which is economical in cost, apparatus and space occupied at an operators position and which is not confusing to the operators.

The invention is especially applicable to signalling the condition of a group of trunks to a trunk operator in a system in which automatic selecting switches are set under the control of a register sender.

Arrangements have already been already been proposed in which the condition of groups of trunks is indicated at an operators position by an indicator comprising a lamp or lamps for each trunk group. With an indicator of this nature any increase in the number of trunk groups involves either an increase in the size of the indicator or an increase in the number of lamps in an indicator which was provided initially of a size large enough to meet such increase. In

either case a considerable amount of space is taken up and alterations are required. It is an object of the invention to overcome the disadvantages of an indicator of this nature.

` In the present invention, at an operators posi- 3()` tion an indicator to which access may be had from the position and which serves to indicate the condition of a group of junctions or trunks hereinafter and in the appended claims referred to as trunks, or the route over which the call is to proceed is common to a plurality of groups of trunks. The indication may be audible or visual and the connection of the indicator to the signalling source may be under the control of apparatus responsive to digits transmitted by the operator for the determination of the trunk group in which it is desired that the call shall proceed. The digit responsive apparatus may be that which actually brings about the routing of the call. Thus, the only trunk group indication given at an operators position -is that for the group with which the operator is concerned.

It may be that arrangements are provided whereby if all the trunks of a group are busy an alternative route is selected in which case the indication given will be such as to convey this information. The connection of the appropriate signalling source may therefore be under the control of the apparatus, such as group control apparatus, which determines whether a direct or alternative route is to be taken.

In a system using register senders, translating arrangements may be provided whereby automatic selecting switches may be caused to select an alternative route if all the trunks in a direct route are busy. Translation may be normally 5 employed: for the routing of a call to a group of direct trunks. The setting or variable connection of the translating apparatus causes a distinctive signal to be transmitted to the operators position whereby a lamp is caused to light steadily or l0 flicker or flash or a continuous or interrupted tone is given in the operators receiver. An indication that a direct route is available, this being the normal route to be taken for a call, may even be signalled negatively, i. e., the lamp is not lit or 15 no tone is heard.

By `the use of group control arrangements, searching by selectors over busy groups may be prevented and these arrangements may determine the application of the appropriate signalling con- 20 dition. The signal may thus be transmitted before any digits are sent out by the register sender. Indeed, in the case of delay working it might be undesirable to send out any digits for the time being. The signal may be transmitted consequent 25 on the operation of a routing relay connected to a group control wire. There may be two routing relays which by their operation determine whether a translation to be effected shall be for a direct route or an indirect route, the operation 30 of the relay eiecting the application of one signalling potential, e. g., a steady potential to the signalling wire, the operation of the other relay effecting the application of a diierent potential or an intermittent application of the same poten- 35 tial as applied bythe first mentioned relay or even no potential. A further relay may be provided adapted to be operated in particular circumstances, for example by the connection thereto of operating potential at a supervising position when 40 delay working is in force in a trunk switching system. rIhis relay may effect the application of a potential to the signalling wire different from the potentials applied by the routing relays. It may also prevent the commencement of digit trans- 4.5 mission by the register sender by opening the circuit of the relay which automatically starts the sending action. This automatic starting relay may be operated over a wiper and contact of the digit, distributor in a position following that in 50 which the last register is connected, or in some cases, over an earlier contact, if the maximum number of digits provided for is not required for the call in question. The automatic starting relay by its operation may bring about the opera- 55 tion of a direct starting relay which locks up and brings about the commencement of the sending action. Arrangements may be provided in which the sending may be started in a position of the distributor prior to that in which the automatic starting relay is operated by providing a circuit for the direct starting relay over a further wire to the position circuit where a suitable potential may be applied to it by a key in the digit key strip. In this way an operator is enabled to set trunk selecting switches while delay working is in force, the connection being completed or the call stored in a storage circuit depending on circumstances. The signalling wire, may in the position circuit, be connected to a lamp and to the operators receiver whereby visual and audible indications are given. A relayin the signalling wire circuit in series with a break contact of itself may provide for a high pitched continuous tone or a like `tone interrupter at flicker or flashing speeds.

The signalling condition is maintained as long as the register sender is in association with the cperators position.

An embodiment of the invention is shown by way of example in the accompanying drawing.

The drawing shows above the chain line so much of the apparatus. at a trunk ofperators position circuit and below the chain line so much of the apparatus in a register sender circuit as is necessary for the understanding of the invention. The complete circuits are shown and decribed in British specication No. 8378/ 36. The parts shown in the drawing accompanying the present specifi-cation bear the same reference characters as the corresponding parts shown in the drawings yaccompanying the said specication and additional reference characters are employed where necessary.

in the trunk operators position circuit are shown an operators induction coil having its primary winding designated OIP and its secondary winding OIS, an instrument jack OJ, relay GT, lamp GCL and key STK. The key STK may be one included in the operators digit key strip for starting the sending or" impulses and the key may be connected to earth to close, when operated, the circuit of a battery connected relay, the relay on operation applying battery to the wire leading to the register sender circuit. A register sender is coupled to the position circuit when required by a coupling switch some of the wipers of which designated SC, SCi, and SCI are shown. In the register sender circuit are included two switches, a distributor, which is of the pawl and ratchet type, wipers of which are shown designated DD and DDS and a translating switch which is set in accordance with keyed digits recorded on registers and which by me-ans of suitable cross connections between contacts of the registers and the banks of the switch provides in its several contact positions translations of the registered digits for the purpose of setting automatic trunk selecting switches. There are included in the register sender circuit group condition determining relays comprising the routing relays PY and SY and a delay working relay DG which are controlled by group control and supervisory arrangements. These relays are adapted to be connected over wipers of the translating switch to the group control and supervisory arrangements and to be controlled thereby in accordance with the setting of the translating switch which itself is dependent on the trunk group required as determined by the Vdigits transmitted by the operator by means of the digit keys. CMU is the driving mechanism of the translating switch and represents the latch magnet of a latch-controlled motor-driven uniselector, the motor of which is connected up by a contact operated by the latch magnet armature. An oir" normal contact of this switch is designated cmonl. T is the test relay for the translating switch, AS a relay for bringing about automatically the commencement of digit transmission by the register sender, SR. is a direct starting relay the operation of which may be effected by relay AS or by operator action after the keying of any number of digits provided for and S may be considered as an auxiliary oi SR. CT is a relay which conne-cts the group condition determining relays to the translating switch. Contact C85 is a contact of a relay CS which is only operated on calls which are to be completed over another trunk exchange. Contacts awl and am are contacts of the register relays which record the first keyed digit andcontacts cw and cx are contacts of the register relays which record the third keyed digit. Contacts of other relays are connected as required in 'those connections indicated by broken lines. The transmission of digits from the register sender to trunk selecting switches involves the marking of from l to 4 wires. which extend to code marking relays in the trunk selectors but as these are not involved in the operations of the present invention it is to be understood that wipers DD and SC each represent 4 wipers of the respective switches and that wiper CM represents the eight wipers concerned with the translation of the digits for effecting markings of rst and second trunk selectors for the selection of direct and alternative routes.

The operation of the circuits shown is as iollows. When an operator wishes to set up a trunk connection she throws keys associated with the connecting circuit she intends to use and causes a register sender to be coupled to her position circuit. She then keys up the number of the required trunk, and this number is recorded on registers in the register sender. Two digits serve to designate the trunk and a third digit is keyed to bring about an indication at the second trunk selector that search of the trunk group is to be made or that a particular trunk is to be selected. As soon as the second digit has been registered and the distributor has moved to position 3, relay CS is operated, contact m03 or cm3 being closed, and contact 085 closes a circuit for the latch magnet CMU. The magnet operates and the translating switch is driven in search of a marking applied by the iirst two registers. Relay CS locks up over another winding. When the marking which is applied as cross connections between the banks of wipers CMI2 and CMI3 is encountered by the switch, relay T operates, opens the latch magnet circuit at contact ti, thereby stopping the switch, and operates relay CT. The position of the translating switch is now indicative of the trunk required. A third digit, the digit l, is received and recorded to cause the second trunk selector to hunt in the required group. Contacts cti tol ot having closed, relays DG, PY, and SY are connected over wipers CMS, CMH) and CMII to the group control arrangements associated with the trunk group concerned. If delay working is in force Iearth will be applied by means of a supervisors key to the contacts in the banks of wipers CMQ and CMi. When delay working is not in force and there is a direct trunk free, earth will be applied to the contact in the bank wiper CMI I. If there is no free trunk in one or both of these routes, group control arrangements will disconnect these earths to prevent operation of relays PY and SY over the wipers of the translating switch.

It will iirst be assumed that there is a direct trunk free. Relay PY operates in a circuit fromA earth in the group control arrangement, wiper CMIIi, contacts ctZ, cw3, 0x3 and sy4 upper winding of relay PY to battery. Relay PY locks up over its lower winding and contact pyl. Contact pyZ opens to prevent operation of relay SY which is rendered slow in operation bymeans of a copper slug. No connection is made to Wiper SCI so that lamp GCL is not lit and relay GI-I is not operated to give the operator an audible signal. The operator thereby knows that the call is being routed over a direct trunk. v'It could, as will be appreciated, be arranged for a contact of relay PY to connect wiper SCi over the back of'contact dgl to a distinctive signalling potential such, as,

for example, earth applied intermittently to flash the lamp GCL and operate relay GT at intervals. The third digit having been recorded the distributor steps to position li in which, relay CT` having been already operated, a circuit is closed for relay AS over its right-hand winding and contacts dg and ct5. Relay AS operates and at contact as! closes a circuit for relay SR. Relay SR locks up over its contact srl and at contact srl closes an operating circuit for relay S. Other contacts of relay SR are not concerned with the arrangments illustrated for carrying out the present invention. On the operation of relay S, contact si completes a circuit including wipers CM, DD and SC over which markings are applied to the code marking relays of the 'rst-trunk selector. The remainder of the operations concerned with the setting up of the connection are Without interset in the 'present invention and will not be referred to.V Y

Should all the direct trunks in the desired route be busy but a free trunk in an alternative route be available, relay PY will notl be operated but relay SY will operate in a circuit from earth in the group control arrangements associated with the alternative trunk group, wiper CMII, contacts Ci, cwi, cmd and m12, lower winding of relay SY to battery. The relay locks up over its upper winding and contacts sy and pyI. Contact Syd disconnects relay PY from wiper CME@ to prevent operation of that relay and consequent mutilation of the code markings should a direct trunk now become free, contact .sg/5 opens to present operation of relay PY consequent on the operation of relay S and closure of contact sl and contact sy connects earth over back contact dgl and wiper SCi to lamy GCL and relay GT. Lamp GCL .glows steadily and relay GT operates and interrupts its circuit at contact gtI. By the repeated operation and subsequent release at contact gti of relay GT the relay buzzes and by rapid changes of potential across the condenser GK the potential of condenser OIK is varied accordingly thereby setting up a rapidly varying current in the primary winding OIP of the operators induction coil. A varying current is induced in the secondary winding OIS which is connected to the operators receiver over the plug OJ and the operator hears a continuous buzz and recognises thereby that an alternative route is being taken for the call.

If by the time the trunks of this route are searched they are all found busy, a signal is reverted to the register sender which operates a relay RS (not shown) to close Contact T54. A

circuit over this contact and contact ctll is closed for the lower winding of relay PY and this relay operates. Relay RS also brings about the release of the trunk selectors as described in the earlier specification referred to. Contacts pyl and pyZ open the circuits of relay SY which extinguishes lamp GCL and stops relay GT buzzing and after an interval during' which the distributor is stepped rapidly to the position in which the code marking circuit for the rst trunk selector would have been: applied, a marking is appliedto cause the trunk selectors `to'be set vto search for a free direct trunk but since all of these are known to be busy, the call is stored' in storage equipment associated with the group concerned. It may here be noted that the trunks of the alternative route may servealso as direct trunks to the next eX- change along the alternative route and that trunks in the direct and alternative routes may be taken from different groups of second trunk selectors.

. If at the time the translating switch is set delay working on the particular group of trunks is in force, earth will be connected over a supervisors key to the contact in the bank of wiper CMQ. Relay DG will thereupon operate and at contact dgl connect a flickering earth potential over the interrupter FE and Wiper SCI -to lamp GCL and relay GT. The lamp will flicker and relay GT Will buzz intermittently thereby producing an interrupted tone in the operators receiver. The opening of contact dg2 prevents the operation `of relay AS. The operator may however press'key STK thereby 4operating relay SR directly over wiper SC? and upon relay S operating, relay PY is operated by means of its lower winding over contacts ctfi, sy, and s3and the call may be stored in call storing equipment associated with the second trunk selector.

1A further winding of relay AS is connected in position 6 of the distributor so that calls may be completed over local numerical switches. Such calls involve the numeral I (operating both the relays AW and AX) as the rst digit and relay CS is prevented from operating in position 3 of the distributor switch. If the full number of digits is keyed, relay AS is operated in position of the distributor to start the transmission of switch setting digits. If less than the full number of digits is keyed sending may be started at any time by the depression by the operator of key STK.

After all the digits required have been sent, relay CS is released and when contact cs falls back magnet CMU is energised over contacts cs and cmonl to cause the translating switch to be driven to its home position in which contact cmonl opens. The distributor is also horned in a manner which need not be described here and all the apparatus in the register sender is released and the circuit over wiper SCI for the indicating lamp GCL and buzzing relay GT is opened.

We claim:

1. In a telephone system, an operators position., a plurality of trunks arranged in groups accessible from said position, each trunk having trunking switches associated therewith, a signalling device at the operators position common to all said groups, means controlled by the operator at said position for indicating a desired trunk group, and means for causing said signalling device to give an indication of the condition of said trunk group before any of the said switches associated therewith are operated.

2. In a telephone system, an operators position, a plurality of connective switches, a plurality of trunks arranged in groups accessible from the operators position through said connective switches, a signalling device at the operators position common to all said groups, means independent of said connective switches for indicating the desired trunk group, and means for causing said signalling device to give an indication of the condition of said trunk group before any of said connective switches are operated.

3. In a ltelephone system, an operators position, a register sender associated therewith, a plurali-ty of trunk routes accessible from said operators position, a signalling device at said position common to all said trunk routes, means for operating the register sender in accordance with the desired trunk route, and means in said sender for causing said signalling device to give an indication of the condition of said trunk route.

4. In a telephone system, an operators position, a register sender associated therewith, a plurality of trunk routes accessible from said operators position, a signalling device at said position common to all said trunk routes, means for operating the register senders in accordance with the desired trunk route, and means in the register sender operative in response to the opleration of said means for providing at one time a direct trunk rou-te, at another time an alternative trunk route, and for operating said signalling device in accordance with the route provided.

5. In a system as claimed in claim 3, a means associated with the register sender whereby when direct trunk routes are unavailable, alternative trunk routes may be provided with said signalling device responding in accordance with the available trunk route.

6. In a telephone system, an operators position, a register sender associated therewith, a plurality of connective switches, a plurality of trunk routes accessible from said operators position through said connective switches, a signalling device at the operators position common to all the trunk routes, means for operating the register sender, means in the register sender operative in response to the operation of said means at one time for determining Whether a direct or alternative route is available and at another time for selecting the available route, and means associated with said last means for causing the signalling device to give an indication in accordance with the available route.

7. In a system as claimed in claim 4, a particular relay associated with the available route to operate said signal device in accordance with the route provided.

8. In a system as claimed in claim 4, in which said signalling device at the operators position is a visual signal caused to vary in accordance with 'the route provided.

9. In a system as claimed in claim 4, in which said signalling device at the operators position is of a visual type conveying information of one condition by remaining inactive.

l0. In a system as claimed in claim 4, in which said signalling device at the operators position is an audible signal comprising a steady or intermittent tone induced in the operators receiver in accordance with the route provided.

11. In a system as claimed in claim 4, in which said signalling device at the operators position includes an audible signal comprising a steady or intermittent tone induced in the operators receiver synchronously with a visual signal varying in accordance with the route provided.

HORACE EDGAR HUMPHRES. BERNARD ANTHONY HENSLER.

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