Patent Publication Number: US-3876839-A

Title: Battery feed and ring trip circuit

Description:
United States Patent Schonbrun Apr. 8, 1975 [54] BATTERY FEED AND RING TRIP CIRCUIT 3.749.846 7/1973 Young 179/84 R [75] Inventor: Leslie D. Schonbrun, Fort W hi N Y Primary Examiner-Thomas W. Brown A! &#39;,A F --I-IbblI,Ch dSt&#39;fl Assigneez E &amp; M Communications tome gent or zrm u e 0 en an 1e e Corporation, New York, NY.  
  57 AB TRACT [22] Filed: Mar. 23, 1973 i b f d d S l f l I attery ee an ring trip re ay circuit or a te e- [211 Appl&#39; 344096 phone system in which tripping of the ringing signal is accomplished using only the battery feed and ring- 52 us. c1 179/18 HB ing y with the battery feed relay Providing both a 511 Int. Cl. I-I04m 3/04 ring p function and a battery feed function and with 581 Field of Search 179/18 HB, 18 F one coil of a P of Coils comprising the battery feed relay providing both a holding coil function and an op- 5 References Cited crating coil function depending on the state of the UNITED STATES PATENTS relay- 3 2l8.394 11/1965 Winkelman 179/18 HB 4 Claims, 1 Drawing Figure I 2. RING E2551 I 1 26d1 261:1 28b i 7 281:3 126d I 34 26dZ I TO I 1 1 38 OTHER RING Z START CIRCUITS SIGNAL l l 280- 1 1 I l i l RING START I I SIGNAL i i DISCONTINUE I RINGING 1 SIGNAL PATENIEDAPR 8 I915 RINGER l a I RING RING START SIGNAL RING START SIGNAL DISCONTINUE RINGING SIGNAL OTHER CIRCUITS BATTERY FEED AND RING TRIP CIRCUIT BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to telephone systems and in particular to the battery feed and ringing circuit of a called party or switchboard wherein a ringing signal must be tripped when the called party answers.  
 2. Description of the Prior Art In conventional two wire telephone systems. battery (negative) voltage is connected to one of the wires, which is normally designated the R wire, and ground or positive voltage is connected to the other wire, which is normally designated as the T wire. When, for example, the line is seized by lifting the telephone hand set, a resistive connection is made between the T and R wires to energize a battery feed relay which indicates, through suitable contacts, that the line is requesting service. On an incoming call to the telephone apparatus, a ringing relay is normally energized. This relay through its associated contacts, disconnects one wire of the line from the battery feed relay and connects that wire to a source of ringing current, such as a ringing generator. The ringing current activates a call signal until the subscriber answers or the telephone apparatus is seized to provide a loop closure. In such prior art circuits, a separate ring trip relay responsive to the loop current is normally energized in order to deenergize the ringing relay and to reconnect the telephone line through the battery feed relay to signal that a call has been answered. Some prior art circuits have eliminated the separate ring trip relay by utilizing a battery feed relay to perform both the battery feed function and the ring trip function. However, such prior art systems require that such a battery feed relay comprise at least three relay coils, one of the coils being a holding coil to insure that the battery feed relay is maintained energized during the transitional when the ringing relay is deenergized. Such a prior art system also requires a complex arrangement of switches operated by a ringing relay as well as additional switches operated by the battery feed relay. Thus, prior art ring trip relay circuits contain unnecessary circuitry, such as separate ring trip relay or additional relay coils and associated switches to perform the battery feed and ring trip functions resulting in increased costs and inefficient operation. The present invention overcomes these disadvantages of the prior art without any loss of function or sacrifice as to reliability and performance.  
 SUMMARY OF THE INVENTION The present invention is directed to an improved battery feed and ring trip relay circuit for a telephone system comprising a telephone apparatus, a ringing current source, a ground line and a battery line, a battery source, a battery feed relay means and a ringing relay means wherein the battery .feed relay provides both a ring trip function and a battery feed function and one coil of a pair of relay coils comprising the battery feed relay provides both a holding coil function and an operbattery feed relay means, as previously mentioned, includes a pair of relay coils with the ganged selection means operatively connecting the pair of battery feed relay coils together in a holding path in the first contact position thereof and operatively connecting one of the pair of battery feed relay coils to the battery source in an operating path in the second contact position thereof. The battery feed relay and the ringing relay each have an associated release time between an energized state and a deenergized state. The ringing relay selection means transfer time is preferably at most 25% of the battery feed relay release time and, most preferably, is less than 25% of the battery feed relay release time. The holding path comprises the one battery feed relay coil operatively connected to the battery wire which is in turn operatively connected through the telephone apparatus to the ground line and, therefrom, through one of the ganged selection means pair to the other battery feed relay coil and, therefrom, through the other of the ganged selection means pair to ground. The operating path comprises the battery source operatively connected through the one battery feed relay coil to the battery wire which is in turn operatively connected throught the telephone apparatus to the ground line and, therefrom, through the previously mentioned one of the ganged selection means pair to the ringing current source and, therethrough, to ground. The selection means is in the first contact position when the ringing relay is deenergized with the battery feed relay remaining energized during the transfer time through the holding path, the battery feed relay thereafter becoming deenergized so that both the battery feed relay and the ringing relay are deenergized in a steady state condition of the circuit.  
 BRIEF DESCRIPTION OF DRAWING The single FIGURE is a schematic diagram of the preferred embodiment of the present invention.  
 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing, a telephone apparatus, generally referred to by the reference numeral 10, is diagrammatically shown. This telephone apparatus 10 preferably comprises a transmitter portion or microphone 12, a receiver or speaker portion 14, and a conventional hook switch 16 which is normally closed when the telephone hand set, normally containing the transmitter 12 and receiver 14, is removed from the cradle therefor normally provided. As shown, the telephone system is preferably a two wire telephone system in which a ground line 18 labeled T and a battery line 20 labeled R are provided. The call circuit for the telephone system illustrated in the FIGURE, preferably includes a conventional ringer 22 and a capacitor 24 which are connected together in a series branch across the telephone set 10. In addition, the telephone system also preferably includes a battery feed relay 26 which preferably comprises a pair of relay coils 26a and 26b. As will be described in greater detail hereinafter, coils 26a and 26b are preferably the usual balanced coils of a conventional battery feed relay, with coil 26b serving as both a holding coil and an operating coil in accordance with the present invention. The telephone system also preferably includes a ringing relay 28 comprising ringing relay coil 28a and transfer contact selection means 28b and 280 which, as shown and preferred, are  
 ganged together and controlled by relay coil 28a of the ringing relay 28. Preferably, ringing relay 28 is a transfer contact relay having a transfer time which is at most 25% of the release time of the battery feed relay 26 and, most preferably, is less than 25% of the battery feed relay 26 release time. The transfer contact of the ringing relay 28 are designated 2801 2802 and 2803 for selection means 280 and 28b1 28b2 and 28b3 for ringing relay selection means 28b. Most preferably, the transfer time of the ringing relay 28 ganged selection means 280-2811, which is defined as the time for the selection means 280 and 28b to transfer from Contact position 2801-2802 to 28022803 selection means 280 and between 28b1-28b2 and 28b2-28123 for selection means 281], is less than 5 milliseconds and the battery feed relay 26 release time is preferably 25 milliseconds In this manner, as will be described in greater detain hereinafter, the timing of the circuit is such that during the release of the ringing relay 28 which causes the selection means 280-281) to switch from one contact to the other contact position, the battery feed relay 26 does not have time to release. Typically by way of example, the ringing relay 28 could be an XWK 55 type, manufactured by Oki Electronics, of Japan.  
  Except as described in the following, the operation of the telephone system including the battery feed and ringing relays is conventional and. in order to simplify the description of the invention, the standard battery feed and ringing relay circuit have not been illustrated. The selection means or switch means operated by the battery feed relay 26 are designated 260 and 26d respectively with the associated relay contacts being designated 2601 and 2602 for switch 260 and 26d1 and 26112 for switch 261/. For purpose of illustration, all relay contacts for both the ringing relay 28 and the battery feed relay 26 are illustrated in the steady state condition of the circuit which is the condition which the associated relay coils 28a and 26a and 26b are all deenergized.  
  Preferably, ringing relay selection means 280 and associated transfer contacts 2801, 2802 and 2803, are adapted to open the ground telephone line 18 when the ringing relay 28 is energized and to connect the ground line 18 to a source of ringing current, such as a conventional ringing generator 30, via path 32. The other ringing relay selection means 28b which is preferably ganged to selection means 280, and includes transfer contacts 28b1, 28122 and 28b3, preferably disconnects one side of the battery feed relay coil 2601 from ground and creates a short circuit via path 34 around the coil 26a which preferably functions as an anti-chattering circuit as described below.  
  Battery feed relay coil 26b is preferably connected between a negative battery source (not shown) and battery line 20. This results in energization of the battery feed relay 26 when the telephone is answered, that is when switch 16 is closed. Battery feed relay switch 260 and associated contacts 2601 and 2602 are preferably connected in the energizing circuit for ringing relay 28 coil 28a in order to deenergize the ringing relay 28 immediately upon seizure of the telephone line. If desired, an additional switch 26d ganged to switch 260 may be provided with additional contacts 26111 and 26d2 in order to transmit a signal to other equipment which, in turn, will de-energize ringing relay 28 when desired in lieu of switch 260 and associated contacts 2601 and 2602.  
  The operation of the circuit is as follows. When the circuit is idle, that is, no conversation is in progress and the connected party or equipment is not being rung, ground appears on the ground line 18 via battery feed coil 26a and ringing relay contacts 28121 and 28b2 through switch 28b. No current flows in the circuit because the hook switch 16 is in the open position. If the telephone apparatus seizes the line such as by closure of switch 16 when the hand set is lifted, a resistive connection is provided between the ground line 18 and the battery line 20 through the transmitter 12 and receiver 14. This causes current to flow in the battery feed relay coils 26a and 26b to energize the relay 26.. Battery feed relay 26 then povides suitable signals to contacts (not shown) to indicate that the line is in use. In conventional fashion, the current flowing in the loop provides the transmitter current and interruptions of such current by a dial provide the dialing signals to be transmitted through the system. Battery feed relay coils 26a and 26b are preferably of equal resistance and turns so that the telephone line is balanced against interference from outside potentials. When the call has been completed, and the hand set has been replaced in its cradle, switch 16 is opened which opens the loop to deenergize the battery feed relay 26 which then signals that the call has terminated and the line is free.  
  When it is desired to call the subscriber, the ringing relay 28 is energized by conventional equipment (not shown) in conventional fashion. For example, ringing relay 28 may be energized by the presence of a signal on lines 36 and 38. The ring start signal on line 36 is preferably coupled through the normally closed battery feed contacts 2601 and 2602 to the ringing relay coil 28a. Due to the preferably selected transfer time of ringing relay 28, when the ringing relay coil 28a is energized ganged selection means 280 and 28b transfer to the contact position indicated by the dotted lines between contacts 2802-2803 for 280 and 28b2-28b3 for switch 28b. Selection means 280 in transferring to contact position 2803-2802 opens the ground line 18 to the telephone set and connects it instead to the source of ringing current 30 on line 32. This ringing current is preferably an alternating current which is not blocked by capacitor 24 and, therefore, is coupled across battery feed relay coil 26b, the direct current path through the telephone set 10 remaining open by virtue of switch 16. Although the alternating ringing current will not energize the battery feed relay 26, preferably, it can cause chattering of the relay contacts. To prevent this, the battery feed relay coil 26a is preferably short circuited via path 34 by transfer of the ganged ringing relay selection means 28b to contact position 28b3-28b2, the short circuit preventing the relay contacts from chattering.  
  When the call is answered, switch 16 is closed to complete a direct current path between the ground line 18 and battery line 20. This energizes battery feed relay coil 26b through the telephone set 10, ringing relay contacts 2803-2802 and the ringing circuit via path 32 to ground. When battery feed relay 26 is energized, switch 260 through connecting contacts 2601 and 2602, or switch 270! through connecting contacts 26d1 and 26012, opens the energizing circuit for ringing relay coil 28a. Because of the preferred relationship between the ringing relay transfer time and the release time of the battery feed relay 26, when ringing relay 28 is deenergized, battery feed relay coil 26b is connected in a holding path via path 20, through hook switch 16, receiver 14 and transmitter 12, to the ground line 18, between contacts 28c2 and 2801 via switch or selector means 280, and therefrom through battery feed relay coil 26a to ringing relay contacts 28b2 and 28121 via selection means 28b to ground. In the position when the ringing relay coil 28a is energized, the battery feed relay coil 26b is connected in an operating path from the battery negative source to the coil 26b to path 20, therefrom, through switch 16 to receiver 14 and therefrom to transmitter 12, therefrom to ground line 18 and through ringing relay contacts 2802-2803 via selection means 28c and, therefrom via path 32 through ringing generator 30 to ground. Thus, battery feed relay coil 26b serves as both a holding coil and an operating coil depending on the state of the ringing relay coil 28a and the result contact position of the selection means 286 and 28b. Thus, when the ringing relay 28 is deenergized, its contacts return to the illustrated condition and during the transfer time the battery feed relay 26 is maintained energized by the above described direct current path through the coils 26b and 26a. Thereafter,  
 . the battery feed relay 26 becomes deenergized to return the circuit to the steady state condition.  
  It should of course be understood that the invention is not limited to any particular environment. It may be used in trunk circuits, link circuits, intra-office trunk circuits, adapter circuits, inter-face circuits of tele phone exchangers, private branch exchanges, private telephone systems, inter-communications systems, telephone equipment located on customer premises, and, generally any type of telephone system where battery and ground must be fed to a telephone line and a ringing signal trip by seizure of a line to provide a loop closure either directly or through other apparatus. The additional functions provided by the battery feed and ringing relays are not material to the invention which would also have utility where helper relays are provided for these relays.  
 I claim:  
  1. In a battery feed ring trip circuit for a telephone system comprising a telephone apparatus, a ringing current source, a ground line and a battery line, a battery source, a battery feed relay means and a ringing relay means, the improvement wherein said ringing relay means comprises a transfer contact relay means including a relay coil means and a plurality of transfer contacts, said transfer contacts including first and second ganged transfer contact selection means transferable between a frist transfer contact position and a second transfer contact position, said ganged transfer contact selection means having an associated transfer time between said first and second transfer contact positions; and said battery feed relay means includes a pair of relay coils, said ganged transfer contact selection means operatively connecting said pair of battery feed relay coils together in a holding path in said first transfer contact position and operatively connecting a common one of said pair of battery feed relay coils to said battery source in an operating path in said second transfer contact position, said battery feed relay means and said ringing relay transfer contact relay means each having an associated release time between an energized state and a deenergized state, said ringing relay transfer contact selection means transfer time being at most 25% of said battery feed relay release time, said holding path comprising said one common battery feed relay coil operatively connected to the battery wire which is operatively connected through the telephone apparatus to the ground line and therefrom through one of said ganged transfer contact selection means pair to the other battery feed relay coil and therefrom through the other of said ganged transfer contact selection means pair to ground, said operating path comprising said battery source operatively connected through said one common battery feed relay coil to the battery wire which is operatively connected through the telephone apparatus to the ground line and therefrom through said one of said ganged transfer contact selection means pair to said ringing current source and therethrough to ground, said transfer contact selection means being in said first transfer contact relay means position when said ringing relay transfer contact is deenergized, said battery feed relay means remaining energized during said transfer time through said holding path, said battery feed relay means thereafter becoming deenergized, both said battery feed relay means and said ringing relay transfer contact relay means being deenergized in a steady state condition of said circuit, whereby said battery feed relay means provides both a ring trip function and a battery feed function and said one common coil of said battery feed relay pair provides both a holding coil function and an operating coil function.  
  2. A circuit in accordance with claim 1 wherein said ringing relay transfer contact selection means transfer time is less than 25% of said battery feed relay release time.  
  3. A circuit in accordance with claim 1 wherein said ringing relay transfer contact selection means transfer time is less than 5 ms and said battery feed relay release time is substantially 25 ms.  
  4. A circuit in accordance with claim 1 further including a normally open anti-chattering short circuit associated with the other of said battery feed relay coils, said other of said ganged transfer contact selection means pair closing said anti-chattering short circuit for said other battery feed relay coil means in said second transfer contact position thereof, said transfer contact selection means being in said second transfer contact position when said transfer contact ringing relay means is in said energized state, whereby chattering of the battery feed contacts is minimized.