US2483214A - Telephone alarm call system - Google Patents

Description

P 27, 1949- c. E. LOMAX 2,483,214

TELEPHbNE ALARM CALL SYSTEM v Filed April 16, 1945 2 Sheets-Sheet 1 GEN Fig.1.

. INVENTOR CLARENCE E. LOMAX ATTORNEY Patented Sept. 27, 1949 TELEPHONE ALARM CALL SYSTEM Clarence E. Lomax, Chicago, 111., assignor to Automatic Electric Laboratories Inc., Chicago, 111., a corporation of Delaware Application April 16, 1945, Serial No. 588,623 g I In Great Britain May 11, 1944 6 Claims.

The present invention relates to telephone alarm call systems by which is meant arrangements whereby individual subscribers can be signalled over their telephone lines at prearranged times so that the telephone bell is made to perform the functions of an alarm clock.

Arrangements have already been adopted to furnish service of this type but it has usually been performed manually as the demand has not been very great and thus it has been well within the capacity of the operating staff particularly as it was mostly required at times of comparatively light traffic. The object of the present invention is to provide arrangements whereby service of this character may be provided to a considerable number of subscribers on an automatic basis so that practically no attention is needed on the part of an-operator or attendant beyond confirming that all the various subscribers concerned have acknowledged the call made to them at the appropriate time.

According to the invention, in a telephone system provided with facilities for automatically signalling certain subscribers at predetermined times a stepping switch arranged to be advanced at predetermined intervals serves to operate equipment common to a plurality of subscribers who require signalling at the corresponding time which equipment thereupon controls the application of ringing current to the lines concerned if they are not in use. V

The invention will be better understood from the following description of two methods of carrying it into effect which should be taken in conjunction with the drawings accompanying the specification which are referred to as Figs. 1 and 2.

Referring first to Fig. 1, the drawing'is shown separated into three portions by dotted lines and the equipment common to the whole exchange is indicated in the lefthand portion, that common to all subscribers who require signalling at a particular time in the middle portion, and that individual to one particular subscriber in the righthand portion. The common equipment comprise essentially a rotary switch G which is arranged to be driven through one complete revolution in the 24 hours and is preferably moved step-by-step by pulses from a clock. This switch does not engage its contacts continuously but is arranged to stand for a time in a blank position between successive contacts. For instance, suppose it is decided that satisfactory service can be given by catering for times at 15 minute intervals, the switch G would be provided with 96 contacts and might be steadily operated by pulses at 7 /2 minute intervals to make 192 steps for a full revolutiom In these circumstances contact would be made for 7 minutes and then there would be a disconnection for the succeeding 7 minutes. It will be understood that the exact mechanical details'of the switch G are not of primary importance and that it might comprise a switch with a much smaller number of contacts, for instance 24, and a number of wipers, for instance eight, which were connected up in turn by a suitable arrangement of relays. Moreover, it is not essentialthat the period of disconnection should equal the period of connection but only that there should be an appreciable pause between successive operations.

The equipment common to the exchange also includes a cam F which-is conveniently arranged to make one revolution sayin, One minute, and accordingly operates relay E for a short period at these intervals, whereby starting earth is con nected to the various individual units of equipment as will be explained subsequently. The function of the relay E could also be taken care of by having a number of contact springs directly operated by the cam. The common equipment also includes a continuously operating double cam device K which is shown diagrammatically and may be arranged to make one revolution every three minutes. The displacement of the two constituent cams is such that the lower cam makes contact slightly before the upper cam, or in other words, that after the upper cam has closed its associated contacts, aperiod of practically three minutes elapses before the lower cam again closes its associated contacts. The common equipment also includes a lamp AL and a bell AB, the purpose of which will be appreciated as the description proceeds.

The equipment individual to a particular signalling time but common to all the subscribers to be signalled at that time comprises the relay D which initiates the operation and relays H and J which serve to control the alarm lamp AL and bell AB. Conveniently with this equipment are grouped the lamps Ll to L4 individual to the different subscribers which are signalled simultaneously at this time;

The equipment "individual'to each subscribers line comprises a group of three relays A, B and C from which connectionis made by way of the bracketed conductors on 'the extreme right to the negative, positive and private conductors of the associated line. Similar connections are 3 made for other subscribers lines and other times.

Assuming now that the equipment illustrated is due to function, when switch G advances to engage the contact succeeding that shown, relay D is operated and with the timing assumed remains operated for-T minutes. When relay E is next operated, -which will be after a period which cannot be longer than the time taken for one revolution of the cam F, earth supplied by contacts of relay E is extended over operated contacts of relay D to the lower windings of the B relays associated with all the, subscribers. corrcerned at this time. It will be seen that theother terminals of these windings are connected to the subscribers P conductors. and consequentl if any line is busy, the conductor will: be earthed. Moreover if the line has been busy for longer than the operating time of relay C, this relay also will be in operatedzcondition and will have opened a point in the initiating circuit. Relay C is made slightly slow to operate in order to enable the cutoff relay, in the subscribers line circuit to die-energize; so as. to prevent false opera-. tion. if the line becomes idle during h period that relay E; is. operated. If the line is not. busy, however, relayfB operatesgin serieswith the cutoff relay and relay C, n. p r el and thereupon o s. o r. p er w nd n dependent upon relay 13, applies earth to theP conductor to busy the line. hereby short circuiting its own lower winding, disconnectsrelay C and connects ring,- ing current by way, of the lower winding of. relay A tothe line conductors. This connection of the ringing generator over the lead GEN may be direct so as to.g ive a continuous ring, or by; way of a special interrupter which will give a characteristic codeto distinguish the alarm call froman ordinary telephone call, It will be appreciated that the other partieswho. are to be given alarm service at this particular time are dealt with in the same way. If any line is busy, a further test will be made when. relay E is next. operated aiter, a further revolution or the cam F. It may wellbe considered, however, that the engaged condition of the line is due to a call 'extended thereover and; accordingly that the party for whose benefit the alarm service is provided is already awake and" aware of the time.

When a party being signalled replies to the alarm call;by removinghis receiver in the usual manner, relay A operates on the direct current loop over its lower winding in the normal. manner ofa ring trip relay and at its X contacts locks up dependent upon relay. B. Relay A thereupon disconnects the ringing, lights the lamps Ll individual to the subscriber andremoves one of the multiple earths from the locking circuit of relays H and J. It will be seen that when the upper contact controlled by cam K is next closed after relay D operates, acircuit is completed for the lower windingof relay-H which thereupon locks up-by way of itsupper winding,- assuming the subscribers. have not yet-all replied, andprepares a circuit for. relay -J. This-circuit is'closed approximately threelminutes later if relay H isstilloperated andt relay J- thereupon energizes andlocks up to the same multiple earth if it isstill available, Ifby this time allthe subscribers concerned have replied, however,- all the A relays will be operated and there: will be no locking circuit for relaysH and J, Theoper-ation of relay J completes acircuit fore-the common alarm bell AB-andthe lamp AL. With-the timingsuggestedthis operation will take place between three and six minutes after the calls were initiated and since the conditions are maintained for 7 /2 minutes, the attendant will have time to check over the lamps Ll to L4 which are still not lighted and to take what action seems desirable to investigate why no replies have been received. At the end of the 7 /2 minutes period when switch G steps off its contact, relay D releases and the locked up A and B relays then also release and conditions are. fully restored to normal.

Referring now to Fig. 2, this shows a slightly modified arrangement in which the general conditions remain the same and accordingly similar reference numerals have been used for corresponding pieces of equipment. The drawing is again divided by dotted lines into three parts representing respectively equipment common to the whole exchange, equipment common to all the subscribers concerned at one particular signalling time and equipment individual to a particular subscribers. line. The chief differences in the. circuit arrangements are that instead of individual. lamps for each subscriber a group of lamps is made to; serve successively for the subscribers concerned at difierent signalling times, cam F and relay E have been' eliminated, alarm. relays H and J: are made to. serve in turn for each signalling time and a key M. is provided as a convenientmeanszof releasing relays H and J if one or more fail; to respond to. the alarm call. Moreover; relay B. is arranged. to be released on the operationof' relay A so that the line is rendered free: immediately after the alarm call has been. answered;v The. general method of operation. of the equipment of Fig. 2'is the same as that of Fig. 11 but it will bev traced. through briefly and attention called to special. points of difference.

When the switch; G steps. to: the next contact after that which it is shown. engaging, earth is appliedto-operatesrelay D; This-thereupon prepares circuits for'theindicating. lamps, prepares locking circuits for relays;-L,.A, B, H 'andJ, connects earth to the:lower windlng. of the various- Brelays, prepares-a circuitifor relay H and lights the lamp LT corresponding to the particular time concerned; If thelineshownrisidle, relay Boperates and. asbefore connects up ringing current from the lead GEN; busies the line and disconnects relay C. If the line is: busy, the operation of relay:Bziszprevented but if it becomes idle at anytime during thesignalling period relay B is then, enabledsto. operate on the release of relay C. When. the party-concerned responds to the alarmcall; relay A operates todisconnect the ringing, to lock up over its upper winding, to release relay B? Icy-opening bothits initial and locking circuits, to-open apoint in thecircuit of the-lamps and: to'open a multiplepoint in the locking circuit of relaysH-andJ,

Assumingthat all thepartiesconcerned-respond before relay H1 isoperated by the action of cam K; all the equipment-is restored' to normal when the switch G steps ofi the contact concerned, whereuponirelay:D releases and brings down the various. operated relays. Whenthe contacts oper'atedby the upper cam Kareclosed, a circuit is completed for-relay Hwhich-thereupon locks up by way-of itsmpper windlng; assuming that at least one-partyhas not yet-replied: Ifall the parties-have-already replied} relay His only operated momentarily.- Assuming; however, that it is able to remain operated, 'it' -prepares-a circuit forrelay J by'way' of the lower camcontacts K and approximately three minutes after the operation of relay I-I, relay J is operated and locks up to the same multiple earth. Thereupon it completes a circuit for the lamps Ll-L4 corresponding to the subscribers who have not yet replied and also completes a circuit for the alarm lamp AL and bell AB.

If the attendant desires to out off the alarm and extinguish the lamps, he may momentarily operate the key M whereupon a circuit is completed for relay L. This relay locks up dependent upon relay D, opens the locking circuit of relay J and the initial and locking circuits of relay H so that both these relays de-energize, the alarm is cut off and the lamps are extinguished. Alternatively, if the attendant decides to allow the alarm operation to continue and all the subscribers subsequently respond, the operation of the last A relay will release relays H and J and only relay D and the various A and possibly C relays will remain operated. When the switch G steps off the contact concerned, relay D releases and brings down the A relays and also relay L if it has been operated and all the equipment is then restored to normal in readiness for controlling a similar signalling operation 15 minutes later.

The invention therefore provides a very simple arrangement whereby alarm call service may readily be provided on a large scale with the minimum of attention and by the use of a comparatively small amount of equipment.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:

1. In a telephone system, an exchange having a plurality of subscriber lines outgoing therefrom, time-controlled means at the exchange for automatically applying ringing current to all the idle ones of said lines for an interval at a predetermined time each day, each of said lines having, at the exchange, subscribercontrolled means for acknowledging the application of said ringing current to that line, an alarm device, a switch operating at a constant rate to measure a predetermined period during the application of the ringing current, and means efiective to operate said alarm device in the event that the application of ringing current to any of said lines goes unacknowledged at the end of said predetermined period.

2. In a telephone system, an exchange having a plurality of subscriber lines outgoing therefrom, time-controlled means at the exchange for automatically applying ringing current to all the idle ones of said lines at a predetermined time each day, each of said lines having, at the exchange, subscriber-controlled means for acknowledging the application of said ringing current to that line, means normally controlled by said last means for giving an alarm at the exchange in the event that the application of ringing current to any of said lines goes unacknowledged for a predetermined period, and an alarm disabling key at the exchange manually operable to prevent said alarm from being given.

3. In a telephone system, an exchange having a plurality of subscriber lines outgoing therefrom, time-controlled means at the exchange for automatically applying ringing current to all the idle ones of said lines at a predetermined time each day, each of said lines having, at the exchange, subscriber-controlled means for acknowledging the application of said ringing current to that line, and means so controlled by said last means in the event that the application of ringing current to any particular one of said lines goes unacknowledged for a predetermined period as to display a visual identification of said particular line.

4. In a telephone system, a group of subscribers lines, a switch operated by a timing device, means responsive to the operation of said switch for applying ringing current to all lines of said group at a predetermined time of the day and to maintain the application of ringing current for a predetermined interval, switching devices effective if one of said lines is busy to prevent the application of ringing current to said busy one line, and said switching devices effective responsive to said one line becoming idle during said interval to apply ringing current thereto.

5. In a telephone system, groups of subscribers lines, a set of signalling devices common to said groups, each signalling device corresponding to a line in each group, means for successively associating said devices with successive line groups and for simultaneously signalling all lines of an associated line group, a circuit prepared for each device by each said successive association, subscriber controlled means individual to each line for disabling the prepared circuit of the signalling device corresponding to such line in response to the subscriber on such line answering during said association, and means for completin the said prepared circuits of only the signalling devices which correspond to the lines failing to answer to thereby operate only the corresponding signalling devices during said association.

6. In a telephone system, a plurality of subscribers lines, a time controlled means for automatically applying ringing current to all the idle ones of said lines at a predetermined time each day, and a relay operatedresponsive to a busy one of said subscriber's lines becoming idle to control the application of ringing current to said one line.

CLARENCE E. LOMAX.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 481,483 Dyer Aug. 23, 1892 549,346 Buell Nov. 5, 1895 940,692 Howard Nov. 23, 1909 1,358,720 Friendly Nov. 16, 1920 1,369,146 Thomas Feb. 22, 1921 1,981,689 Deakin et a1 Nov. 20, 1934 2,298,489 Kiner Oct. 13, 1942

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