US2499475A - Device for registering the locations of personnel - Google Patents

Device for registering the locations of personnel Download PDF

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US2499475A
US2499475A US741604A US74160447A US2499475A US 2499475 A US2499475 A US 2499475A US 741604 A US741604 A US 741604A US 74160447 A US74160447 A US 74160447A US 2499475 A US2499475 A US 2499475A
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contact
bar
operating
relay
place
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Ericsson Erik Arvid
Jacobaeus Anton Christian
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Telefonaktiebolaget LM Ericsson AB
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Telefonaktiebolaget LM Ericsson AB
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    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04MTELEPHONIC COMMUNICATION
    • H04M15/00Arrangements for metering, time-control or time indication ; Metering, charging or billing arrangements for voice wireline or wireless communications, e.g. VoIP
    • H04M15/08Metering calls to called party, i.e. B-party charged for the communication
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04MTELEPHONIC COMMUNICATION
    • H04M11/00Telephonic communication systems specially adapted for combination with other electrical systems
    • H04M11/02Telephonic communication systems specially adapted for combination with other electrical systems with bell or annunciator systems
    • H04M11/022Paging systems

Definitions

  • the present invention relates to improvements in'arrangements for the recording of identification signals in systems arranged forindicating the location place and identity of persons. According to the system a certain number of personscan indicate their presence at any of a number of diiferent places by means of signal transmitters'arranged at the said'places, which transmitterscan beactuated to emit a signal assigned to the person in question.
  • the signal is carried over a line to a-central exchange comprising a number of connecting links of the kind well known in automatictelephony and-comprising two selectors each, one of said selectors being a linefinder, which by a call from a certain place is connected to .the line coming from said place and thus connecting to the line the other selector, which is a final selector.
  • the finalselector is set by a signal (forexampl'e two impulse trains from a dial) emitted from the signal transmitter at the place in question, a connection thus being established between the line finder and a special selector forplace'marking, corresponding to the identity signal of the calling person.
  • the selector for place marking
  • the line finder then brought into a condition'corresponding to the position of the line finder and thus indicates the location from which the signal has been emitted.
  • the person, who has'thus indicated his present location on his place marking selector may then'have his telephone .calls connected to the telephone at the said place.
  • the'rfe is'pro'vided an operators position with a lamp field comprising a lamp combination'for each location at which there is a signal 'transmitter,"and akey for each person.
  • the place marking selectors In plants according to the above description the place marking selectors, one of which is needed for each person, and each of which must have one position for each location, often represent a considerable part of thejtotalfeost of the plant, especially if the number of ypersons and places is great.
  • the present "invention has "for an object to reduce the cost in large'plants, and achieves this by arranging that the selectors for place marking each consists of an-operating bar in a cross bar-switch, on which bar the locations are indicated by the simultaneous closing of more than one contact spring set. This is achieved by actuation of the selecting magnets of the cross bar switch in different combinations; followed by actuation of the operating niagnet of the operatifigbar.
  • Fig. -2 shows additional circuits in the telephonesystem necessaryfor applying the system to the invention
  • I Fig. 3 shows a place markingselector consisting of-an operating'bar in .a crossbar switch according to the invention.
  • F is a telephone instrument or at least adial by the operation of which a call is made over the line Llto le -central exchange which maybe across bar system for example of the type described in US. Patent No. 1,517,331.
  • a call-the line L' is eiitended over contacts in the contact sets -l and '2 ina line finder to' a trunk or link circuit SNR, which over "a Contact set'5 ina sender selector switch SR is connected toa sender REG.
  • the sender is now connected to a m'ai'kerN over the contact' s'e't 6 in a marker connector NS.
  • the marker N cooperates 'with'the sender REGT'for setting the connctor s'witchor finalswitch'LV to the operating bar 'PV'belonging .to "the calling person.
  • the communication is "extended from the link circuitSNR over thecon'tactisets 3 and! to the operating 'bar'PV.
  • The marker N and the senderREG 'a're "released.
  • a circuit is now "closed' over contacts in the contact sets I and 2 to the marker Mwhichby said circuit is set in accordancewith the calling locationor line L.
  • Another circuit is closed over contacts in the contact sets 3 and l to a relay, which connects the selectingmaigne'ts'of the cross bar switch'to which'the ca1led"operating "bar PV belongs, to the marker M.
  • the marker M sets said selecting magnets in a combination "corresponding' to-the calling place'or line-L. Thiswill be described later.
  • the operatingbar'PV . is-ef' a'special construction'in that the bar is normally-in itsoperated position. This is achieved in a simple'way'by the magnetic circuit" of""'the Uibrating magnet "C613 taining at least one part with high magnetic remanence, for example a core of steel, whereby the magnet when energized retains its armature (and bar PV) in operated position after the current through its Winding has been broken.
  • the operating magnet When a call is made to an operating bar PV for place marking, the operating magnet is first de-energized at least for a moment and all actuated contact sets of the operating bar are released.
  • the selecting magnets of the cross bar switch, to which the called operating bar PV belongs have been energized in a combination representing the calling place, the operating magnet of the called operating bar is again energized, thus registering said combination by actuating the contact sets corresponding to the energized selecting magnets.
  • the communication between the calling place and the called operating bar can be released, the latter remaining in operated position.
  • a communication may be set from a calling place or line L with help of an instrument F to an operating bar PV (Fig. 3) by apparatus shown in Fig. 2.
  • the calling line L has the number H, which is marked by closure of the contact set I! in the line finder S.
  • the communication is set over a link circuit SNR which is marked in Fig. 2 by closure of the corn tact set iii in the line finders and of contact set 69 in the final selector LV.
  • the called operating bar PV (Fig. 3) has the number 6'? which is marked by closure of the contact set ii! in the final selector LV.
  • the line L is connected to the link circuit SNR over the contact bars A and B in accordance with a normal automatic telephone system.
  • the winding of the operating magnet BPM for the called operating bar PV in Fig. 3 is connected to the link circuit SNR over the contact bars E and F in the final selector LV.
  • the operating magnet BPM is deenergized and reenergized in the opposite direction by the following circuit: positive battery, contact I ill, contact bar E, the contact sets 69 and 6'1, the conductor f, winding on BPM (Fig. 3), conductor g, contact bar F, contact I03, to negative battery. All contact sets on the operating bar PV are thereby released.
  • a contact Hit in the link circuit is closed.
  • This contact can be operated by the same relay which in a normal automatic telephone system releases the register REG.
  • the following circuit is closed: positive battery, contact I00, the winding of relay RI, the contacts H4, !26H6, to negative.
  • the relay RI operates.
  • the contacts I I it are actuated.
  • the following two circuits are closed: (1) positive battery, contact Hi, contact bar D, the contact sets Bil and 67, conductor e, winding on relay PR (Fig.
  • that corresponds to the line L closes circuits over the contacts ill- I13 for some of said selecting magnets, which together form a combination representing the calling line L or the location of the instrument F.
  • the selecting magnets STMl, STM2 and STME are energized in the following circuits: positive battery, winding on relay Rl2, contacts H3, I'llll3, 60I602 and 8 38, the windings on the selecting magnets STMI2 and STMB, to negative battery.
  • the relay Hi2 has low resistance and is energized at the same time as the selecting magnets.
  • the contact 885 is closed and the relay RH is energized.
  • the contacts Hit-I04 are actuated thereby reversing the current direction through the winding of the operating magnet BPM.
  • the operating magnet BPM thus releases for a moment, during which the selecting fingers on the selecting bars oper-- ated by the selecting magnets STMI, STMZ and STMG for the operating bar PV are moved under the corresponding contact sets H, l2 and iii.
  • the operating magnet BPM is then immediately reenergized, thereby actuating the contact sets H, l2 and I6.
  • the operating bar PV for the calling person has been set in a combination representing the place from which the call was made, and the communication can be released, e. g. by the calling person replacing the receiver on the telephone instrument F.
  • a key PK corresponding to each person and a lamp field T common to all the place marking selectors, said key and lamp field being arranged at an operators position OP.
  • relays TRl-TR3 pertaining to the relay set TR are shown in the Figure 3; by means of these three relays seven combinations of the contact spring sets I 1, l2 and 13 are translated to seven circuits, one for each lamp in a horizontal row of lamps Hi-Hl. If only contact I3 is closed, the lamp H1 glows in the following circuit: Positive battery on bar PV, contact I3, contacts 13 and 3
  • Relay OR is self held over contact 5
  • An acoustic signal for example a bell connected by contact 52 on relay OR, may thus be sounded to call the operators attention to the arrival of the sought person at his new location. This signal may be discontinued by the operator, when desired, by depressing key PC.
  • signal transmitting means at each of said stations operative to transmit signals corresponding to the identities of said persons
  • cross bar switch means including a plurality of operating bars corresponding respectively to signal codes assigned to respective persons, said bars being normally in an operated condition
  • a link circuit including selecting magnet means operative to select a particular bar in accordance with signals received from a respective transmitting means, automatic switching means operable to connect a selected one of said transmitting means to said link circuit, a common marker, means for connecting said :link circuit to said marker for setting said marker in accordance with the particular transmitting means being operated, means in said marker for setting the selecting magnets 01 said cross bar switch corresponding to a selected operatF- ing bar in a combination indicative of said trans ⁇ ,mitting means, means for releasing said operat- ⁇ eluding a key individual to each person and is.
  • signal transmitting means at each of said stations operative to transmit Signals corresponding to the identities of said persons
  • cross bar switch means including a plu jrality of operating bars corresponding respectively to signal codes assigned to respective persons, said bars being normally in an operated condition
  • link circuits including selecting magnet means operative to selecting a particular bar in accordance with signals received from a respective transmitting means, automatic switching means operable to connect a selected one of said transmitting means to said link circuit, marker, means for connecting said link circuit to said marker, for setting said marker in accordance with the particular transmitting means being operated, means in said marker for setting the selecting magnets of said cross bar switch corresponding to a selected operating bar in a combination indicative of said transmitting means, means for releasing said operating bar and immediately restoring the same to operated condition, means under the control of the last named means for registering said combination, and central operating equipment including a key individual to each person, lamp indicator and a relay device, and connections between said keys and said

Description

March 7, 1950 E. A. ERICSSON ET AL 2,499,475
DEVICE FOR REGISTERING THE LOCATIONS OF PERSONNEL Filed April 15, 1947 2 Sheets-Sheet 1 R1 IJLU entoz s /II V March 1950 E. A. ERICSSON ETAL 2,499,475
DEVICE FOR REGISTERING THE LOCATIONS 0F PERSONNEL Filed April 15, 1947 2 Sheets-Sheet 2 Fig.3
112116121701 5 lJiEz eQcssozz/ Patented Mar. 7, 1950 UNITED STATES PATENT OFFICE 2,499,475 Baywatch-REGISTERING rfiELooATIoN-s OFPERSONNEL Erik AruidEricsson and Anton 1Ghristian'Jac0- baeus, Stockholm, Sweden, assignors to Telefonaktiebolaget L M Ericsson, Stockholm, Sweden,"a' company ofSweden hpplicati'onidpril lfi,194'7JSeriaZlNo. 741;604 In' Sweden April 29, 1946 The present invention relates to improvements in'arrangements for the recording of identification signals in systems arranged forindicating the location place and identity of persons. According to the system a certain number of personscan indicate their presence at any of a number of diiferent places by means of signal transmitters'arranged at the said'places, which transmitterscan beactuated to emit a signal assigned to the person in question. H I I The signal is carried over a line to a-central exchange comprising a number of connecting links of the kind well known in automatictelephony and-comprising two selectors each, one of said selectors being a linefinder, which by a call from a certain place is connected to .the line coming from said place and thus connecting to the line the other selector, which is a final selector. The finalselector is set by a signal (forexampl'e two impulse trains from a dial) emitted from the signal transmitter at the place in question, a connection thus being established between the line finder and a special selector forplace'marking, corresponding to the identity signal of the calling person. The selector for place marking,
hereinafter called a place'marking's'elector, is
then brought into a condition'corresponding to the position of the line finder and thus indicates the location from which the signal has been emitted. The person, who has'thus indicated his present location on his place marking selector may then'have his telephone .calls connected to the telephone at the said place. 'For' reading the indications of the place markingsele'ctors, the'rfe is'pro'vided an operators position with a lamp field comprising a lamp combination'for each location at which there is a signal 'transmitter,"and akey for each person.
In plants according to the above description the place marking selectors, one of which is needed for each person, and each of which must have one position for each location, often represent a considerable part of thejtotalfeost of the plant, especially if the number of ypersons and places is great. The present "invention has "for an object to reduce the cost in large'plants, and achieves this by arranging that the selectors for place marking each consists of an-operating bar in a cross bar-switch, on which bar the locations are indicated by the simultaneous closing of more than one contact spring set. This is achieved by actuation of the selecting magnets of the cross bar switch in different combinations; followed by actuation of the operating niagnet of the operatifigbar.
.2 An embodiment-of the invention will .nowjbe described with reference to Figures 1-3 of the accompanying drawings, in which I Fig. 1;is a schematic drawing of the invention combined with a known telephone system,
7 Fig. -2 shows additional circuits in the telephonesystem necessaryfor applying the system to the invention, and I Fig. 3 showsa place markingselector consisting of-an operating'bar in .a crossbar switch according to the invention.
In Fig. 1, F is a telephone instrument or at least adial by the operation of which a call is made over the line Llto le -central exchange which maybe across bar system for example of the type described in US. Patent No. 1,517,331. By a call-the line L' is eiitended over contacts in the contact sets -l and '2 ina line finder to' a trunk or link circuit SNR, which over "a Contact set'5 ina sender selector switch SR is connected toa sender REG. The calls in thisfcase'made by a person who wishes'to indicate on his !place marking' selector PV, his presence at the igplace where the said telephone irisftrument 'ordial isloc'ated. He sends by niean's of the dial a number of impulse series which "corres ond to his place marking selector, which'i's the 'operatin'gbar PV. The sender is now connected to a m'ai'kerN over the contact' s'e't 6 in a marker connector NS. The marker N cooperates 'with'the sender REGT'for setting the connctor s'witchor finalswitch'LV to the operating bar 'PV'belonging .to "the calling person. The communication is "extended from the link circuitSNR over thecon'tactisets 3 and! to the operating 'bar'PV. "The" marker N and the senderREG 'a're "released. As'soon as the communication is com'pletedthe link circuit SNR calls'the"'marker M and, if'this marker "is idle, SNR is'conne'ct'e'd over a contact set in arela'y chain MR'to the marker M. V e
A circuit is now "closed' over contacts in the contact sets I and 2 to the marker Mwhichby said circuit is set in accordancewith the calling locationor line L. Another circuitis closed over contacts in the contact sets 3 and l to a relay, which connects the selectingmaigne'ts'of the cross bar switch'to which'the ca1led"operating "bar PV belongs, to the marker M. The marker M sets said selecting magnets in a combination "corresponding' to-the calling place'or line-L. Thiswill be described later.
The operatingbar'PV .is-ef' a'special construction'in that the bar is normally-in itsoperated position. This is achieved in a simple'way'by the magnetic circuit" of""'the Uibrating magnet "C613 taining at least one part with high magnetic remanence, for example a core of steel, whereby the magnet when energized retains its armature (and bar PV) in operated position after the current through its Winding has been broken.
When a call is made to an operating bar PV for place marking, the operating magnet is first de-energized at least for a moment and all actuated contact sets of the operating bar are released. When the selecting magnets of the cross bar switch, to which the called operating bar PV belongs, have been energized in a combination representing the calling place, the operating magnet of the called operating bar is again energized, thus registering said combination by actuating the contact sets corresponding to the energized selecting magnets. When this is done the communication between the calling place and the called operating bar can be released, the latter remaining in operated position.
Referring now to Figs. 2 and 3 of the drawings, a communication may be set from a calling place or line L with help of an instrument F to an operating bar PV (Fig. 3) by apparatus shown in Fig. 2. It is presumed that the calling line L has the number H, which is marked by closure of the contact set I! in the line finder S. The communication is set over a link circuit SNR which is marked in Fig. 2 by closure of the corn tact set iii in the line finders and of contact set 69 in the final selector LV. The called operating bar PV (Fig. 3) has the number 6'? which is marked by closure of the contact set ii! in the final selector LV. The line L is connected to the link circuit SNR over the contact bars A and B in accordance with a normal automatic telephone system. The winding of the operating magnet BPM for the called operating bar PV in Fig. 3 is connected to the link circuit SNR over the contact bars E and F in the final selector LV. The operating magnet BPM is deenergized and reenergized in the opposite direction by the following circuit: positive battery, contact I ill, contact bar E, the contact sets 69 and 6'1, the conductor f, winding on BPM (Fig. 3), conductor g, contact bar F, contact I03, to negative battery. All contact sets on the operating bar PV are thereby released.
When the communication is completed a contact Hit in the link circuit is closed. This contact can be operated by the same relay which in a normal automatic telephone system releases the register REG. For each link circuit SNR there is a relay R! in a relay chain ME, in which only one relay at a t me can be energized. The following circuit is closed: positive battery, contact I00, the winding of relay RI, the contacts H4, !26H6, to negative. The relay RI operates. The contacts I I it are actuated. The following two circuits are closed: (1) positive battery, contact Hi, contact bar D, the contact sets Bil and 67, conductor e, winding on relay PR (Fig. 3) to negative battery; (2) positive battery, contact H2, contact bar C, the contact sets 66 and I1, the winding on relay RZI in the marker M, to negative battery. The relays PR and R2! thus both are energized. The contacts ill-I13 (Fig. 2) and GH6il5 (Fig. 3) are closed.
From the marker M there is a number of common conductors, in this case 6 conductors, of which 4 conductors, b, c and d are shown in the figures. The 6 conductors are connected by the relay PR over the contacts 60 l-fiiifi to the selecting magnets STMl-STM6 of the cross bar switch to which the called operating bar PV corsets TBA-3 and TR4-6 in Fig. 3.
4 responds. The relay R2| that corresponds to the line L closes circuits over the contacts ill- I13 for some of said selecting magnets, which together form a combination representing the calling line L or the location of the instrument F. In this case the selecting magnets STMl, STM2 and STME are energized in the following circuits: positive battery, winding on relay Rl2, contacts H3, I'llll3, 60I602 and 8 38, the windings on the selecting magnets STMI2 and STMB, to negative battery. The relay Hi2 has low resistance and is energized at the same time as the selecting magnets. The contact 885 is closed and the relay RH is energized. The contacts Hit-I04 are actuated thereby reversing the current direction through the winding of the operating magnet BPM. The operating magnet BPM thus releases for a moment, during which the selecting fingers on the selecting bars oper-- ated by the selecting magnets STMI, STMZ and STMG for the operating bar PV are moved under the corresponding contact sets H, l2 and iii. The operating magnet BPM is then immediately reenergized, thereby actuating the contact sets H, l2 and I6.
Now the operating bar PV for the calling person has been set in a combination representing the place from which the call was made, and the communication can be released, e. g. by the calling person replacing the receiver on the telephone instrument F.
For reading the combination registered by the place marking selectors PV there is provided a key PK corresponding to each person and a lamp field T common to all the place marking selectors, said key and lamp field being arranged at an operators position OP.
When a key PK is pushed, a relay RP is actuated, said relay connecting the contact spring sets for the place marking selector to tworelay In small plants such relay sets may be very simple. As an example the relays TRl-TR3 pertaining to the relay set TR are shown in the Figure 3; by means of these three relays seven combinations of the contact spring sets I 1, l2 and 13 are translated to seven circuits, one for each lamp in a horizontal row of lamps Hi-Hl. If only contact I3 is closed, the lamp H1 glows in the following circuit: Positive battery on bar PV, contact I3, contacts 13 and 3| and 2|, lamp Hi, to negative battery. If the contacts II and 13 are both closed, the relays TR! and TR2 attract their armatures and a circuit is completed over contacts 3! and 22 to the lamp H6. If only the contact I2 is closed, only relay TBS attracts its armature and the following circuit is completed: From positive battery, contacts i5, 25 and 33, to the lamp H3 as shown in the fiure, and so on.
By means of a further set of three relays it is possible to arrange a relay set TR4TR6 for reading the setting of three other contact spring sets pertaining to the place marking selector PV, and for this purpose a further row of lamps Vl-V'l is provided.
By combination of the lamps HI-HT and Vi- Vl, it is therefore possible to obtain 49 difierent readings in the lamp field '1, only 6 selecting magnets STMI-STMB and contact spring sets being used. 20 different combinations can easily be obtained by means of 6 contact spring sets. The number of relays in the relay sets must be correspondingly increased, so as to obtain 20 outgoing circuits from each relay set. By means of two rows of lamps having 20 lamps each it is possible to obtain 400 difierent readings, that is the plant can deal with 400 places.
It cometimes happens that a person who is sought at the place at which he last indicated his presence, has already left that place. In such a case the sought person usually soon indicates is presence at another location. The operator concerned with such indications can then press a key PS, which is individual for the sought person. .As the operating bar PV is normally operated, the contact 4! is normally broken by the operating magnet BPM. Each time the operating bar PV is set by a final selector LV, the contact 4| is however closed simultaneously with the release of the selecting fingers for the contact spring sets. If the key PS is depressed at the time when the contact 4! closes, relay OR, which is common to all'the keys PS, receives current and attracts its armature. Relay OR is self held over contact 5| in a circuit through the key PC, and which circuit can be broken by the operator by pressing that key. An acoustic signal, for example a bell connected by contact 52 on relay OR, may thus be sounded to call the operators attention to the arrival of the sought person at his new location. This signal may be discontinued by the operator, when desired, by depressing key PC.
that we have provided a system accomplishing all of the stated objects of the invention with a minimum cost of installation, but many changes in the details of the proposed system may be made without de arting from the spirit of our invention as defined in the appended claims.
We claim:
1. In a system for re istering the locations of various persons with reference to a plurality of diiferent stations, signal transmitting means at each of said stations operative to transmit signals corresponding to the identities of said persons, cross bar switch means including a plurality of operating bars corresponding respectively to signal codes assigned to respective persons, said bars being normally in an operated condition, a link circuit including selecting magnet means operative to select a particular bar in accordance with signals received from a respective transmitting means, automatic switching means operable to connect a selected one of said transmitting means to said link circuit, a common marker, means for connecting said :link circuit to said marker for setting said marker in accordance with the particular transmitting means being operated, means in said marker for setting the selecting magnets 01 said cross bar switch corresponding to a selected operatF- ing bar in a combination indicative of said trans} ,mitting means, means for releasing said operat- {eluding a key individual to each person and is.
location indicator, and connections controlled by said keys for connecting all the contact sets on the operating bar corresponding to said person with said indicator, whereby the provide an indication of the transmitting means from which said operating bar last was controlled.
2. In a system for registering the locations of various persons with reference to a plurality of different stations, signal transmitting means at each of said stations operative to transmit Signals corresponding to the identities of said persons, cross bar switch means including a plu jrality of operating bars corresponding respectively to signal codes assigned to respective persons, said bars being normally in an operated condition, link circuits including selecting magnet means operative to selecting a particular bar in accordance with signals received from a respective transmitting means, automatic switching means operable to connect a selected one of said transmitting means to said link circuit, marker, means for connecting said link circuit to said marker, for setting said marker in accordance with the particular transmitting means being operated, means in said marker for setting the selecting magnets of said cross bar switch corresponding to a selected operating bar in a combination indicative of said transmitting means, means for releasing said operating bar and immediately restoring the same to operated condition, means under the control of the last named means for registering said combination, and central operating equipment including a key individual to each person, lamp indicator and a relay device, and connections between said keys and said relay device for connecting all the contact sets on the operating bar corre sponding to said person with said indicator, whereby to provide an indication of the transmitting means from which said operating bar last was controlled.
3. The invention in accordance with claim 1, including an operating magnet for each of said operating bars, the magnetic circuit of each operating magnet including at least one portion having relatively high remanence, whereby said operating bar remains in its operated position after the cessation of current through said operating magnet.
ERIK ARVID ERICSSON. ANTON CHRISTIAN JACOBAEUS.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,963,600 Voss June 19, 1934 2,199,824 Kinkead May 7, 1940 2,330,355 Hershey Sept. 28, 1943 2,330,357 Mote Sept. 28, 1943 2,335,524 Lomax Nov. 30, 1943 2,397,881 Nitterauer Apr. 2, 1946
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2913533A (en) * 1957-12-23 1959-11-17 Gen Dynamics Corp Broadcast paging system
US3439320A (en) * 1967-09-21 1969-04-15 Relton Corp Personnel location system

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US1963600A (en) * 1930-10-13 1934-06-19 Associated Electric Lab Inc Signaling system
US2199824A (en) * 1938-04-07 1940-05-07 Bell Telephone Labor Inc Signaling system
US2330355A (en) * 1941-04-26 1943-09-28 Automatic Elect Lab Indicating system
US2330357A (en) * 1941-04-26 1943-09-28 Automatic Elect Lab Signaling system
US2335524A (en) * 1941-04-26 1943-11-30 Automatic Elect Lab Signaling system
US2397881A (en) * 1944-09-26 1946-04-02 American Telephone & Telegraph Signaling system

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1963600A (en) * 1930-10-13 1934-06-19 Associated Electric Lab Inc Signaling system
US2199824A (en) * 1938-04-07 1940-05-07 Bell Telephone Labor Inc Signaling system
US2330355A (en) * 1941-04-26 1943-09-28 Automatic Elect Lab Indicating system
US2330357A (en) * 1941-04-26 1943-09-28 Automatic Elect Lab Signaling system
US2335524A (en) * 1941-04-26 1943-11-30 Automatic Elect Lab Signaling system
US2397881A (en) * 1944-09-26 1946-04-02 American Telephone & Telegraph Signaling system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2913533A (en) * 1957-12-23 1959-11-17 Gen Dynamics Corp Broadcast paging system
US3439320A (en) * 1967-09-21 1969-04-15 Relton Corp Personnel location system

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