Patent Publication Number: US-6658098-B2

Title: Power transfer apparatus for use by network devices including telephone equipment

Description:
RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 08/865,015, filed May 29, 1997 now U.S. Pat. No. 6,449,348. 
     This application relates to, and incorporates by reference, U.S. patent application Ser. No. 08/865,016, filed on May 29, 1997, entitled, “Power Transfer Apparatus for Concurrently Transmitting Data and Power Over Data Wires,” having inventors David A. Fisher, Lawrence M. Burns, and Stephen Muther, and being assigned to the assignee of the present application. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates in general to the field of data networking and communications, and in particular to interconnecting computers to a local area network (“LAN”) or a wide area network (“WAN”) through data lines that carry power, network data and telephone data. 
     2. Description of the Related Art 
     Network devices, such as networked personal computers, typically communicate via wired data lines and receive power from a separate line. For example, personal computers (“PC s”) may communicate ethernet signals via category three (CAT-3) or category five (CAT-5) twisted pair wire and receive power from a second cable connected to a power source, such source, such as a wall socket or a battery. However, it is desirable to be able to eliminate the need for the second cable. 
     The following describes examples of network devices that benefit from the elimination of the separate power line, and then describes some of the inadequacies of previous solutions. 
     Plain old telephone service (“POTS”) combines a voice signal with a power signal. The combined signal is transmitted over twisted pair cable between the telephone and the line card at the public telephone exchange office. The line card also supplies power over the two wires carrying the voice signal. However, the voice signal supported by POTS is not sufficient for bandwidth intensive communications needs, such as, ethernet communications. Similarly, ISDN communications transmit power and digital data over between an ISDN modem and a telephone switch. However, ISDN data rates are more than an order of magnitude lower than ethernet data rates. 
     Additionally, telephone systems using private bridge exchanges (PBXs) typically have a wired connection that is separate from the network devices. This additional wired connection carries both telephone data signals and power to the telephone. The telephone data signals may be either digital or analog data signals that carry the voice conversations to and from the PBX to a telephone. The PBX is responsible for relaying the voice conversation to and from other users or out into the public telephone exchange. The PBX also supplies the telephone with power. In the event of a power outage, the PBX may have a back up power supply to allow users to continue to use their phones during the power outage. 
     POTS does have one important feature which is supported by some PBX systems. During a power failure, the telephone continues to operate. This is because power is supplied to the telephone directly from a backup power system at the PBX or the central switch. This is a desirable feature of telephone systems. 
     In previous systems where a user has both a network device and a telephone, the user will have a cable connected to the network for network communications with the network device, a cable connected to a power source for the powering the network device, and a cable connected to the PBX for powering and carrying communications to and from the telephone. One problem with such a system is the cost of installing and maintaining all of these cables. Therefore, it is desirable to have a system that supplies the same general network device and telephone functionality to the user, but reduces the significant cabling costs of the system. 
     Therefore, what is needed is a solution that reduces the wiring requirements to transmit data and power to a network device and a telephone without significantly reducing the functionality of the network device and the telephone. 
     SUMMARY OF THE INVENTION 
     One embodiment of the invention includes an apparatus for providing electric power to a telephone across a transmission line where the telephone is coupled to a network device. A power and data coupler (“the coupler”) is coupled to one end of the transmission line. The transmission line is also adapted for transmission of a data signal. The data signal includes telephone signal data for communications with the telephone. The coupler has a data input and a power input. Power from the power input is coupled to the data signal from the data input and the combined power supply current and data signal is coupled to one end of the transmission line. The opposite end of the transmission line is coupled to a power and data decoupler (“the decoupler”). The decoupler has a power output and a data output. Both the data output and power output of the decoupler are coupled to the network device. The combined power and data signal is decoupled by the decoupler, and the data signal is supplied to the data output and the power is supplied to the power output. The invention also includes a telephone circuit. The telephone circuit receives the power from the power output and receives the telephone signal data. The telephone circuit couples the power and the telephone signal data together to make a combined power and telephone signal, which can be used by the telephone. 
     In another embodiment, the invention includes a power switch to selectively switch between power from the decoupler and power from an external source. In one embodiment, the power switch selects power from the decoupler when a power outage, for example, causes the external power source to cease supplying power. 
     In another embodiment, the transmission line includes two transmission lines. One of the transmission lines carries both data and power signals. In another embodiment, data and power signals are carried on both of the transmission lines. 
     In other embodiments, the power signal includes alternating current and/or direct current. 
     In another embodiment, the transmission lines include twisted pair cables. 
     These features of the invention will be apparent from the following description which should be read in light of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an overview of an installation of a power transfer apparatus that supports both computer data and telephone data communications. 
     FIG. 2 is an overview of a power transfer apparatus for use with telephone equipment and network devices. 
     FIG. 3 is a schematic diagram of a power transfer apparatus for use with both computer data and telephone data. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following describes multiple embodiments of the invention. In one embodiment, a coupling device couples a telephone signal data and computer data are and transmits the combined data to a network device such as a personal computer. A network interface card in the computer receives the combined data and helps separate the telephone data from the computer data. The network interface card then transmits the telephone data to a telephone connected to the network interface card. When the computer is powered down, such as during a power failure, the coupling device also couples a power signal to the combined data signal. The network interface card uses the power to power the telephone. Thus, a user can still use the telephone during a power failure. 
     In another embodiment of the invention, telephone voice data (also called bearer data) is formatted as ethernet packets. These telephone ethernet packets are communicated with the other ethernet packets in an ethernet network. A network infrastructure device, such as a hub, receives the ethernet packets from the ethernet network, and forwards packets addressed to a particular personal computer to that personal computer. The personal computer includes a network interface card. Coupled to the network interface card is a telephone. The network interface receives the forwarded packets from the hub and extracts the bearer data. The network interface card then couples a power signal from the personal computer with the bearer data. In the event of a power failure, or some other interruption of power from the personal computer to the telephone, a coupler circuit in the hub couples a power signal with the ethernet packets that are being forwarded to the personal computer. The power signal from the hub can then be used to power the network interface card and the telephone. 
     Power Transfer Apparatus Overview 
     FIG. 1 shows the overall configuration of the one embodiment of the invention including a power transfer apparatus. The following lists the elements in FIG.  1  and then describes those elements. 
     FIG. 1 includes the following elements: an external power source  150 ; a power cable  120 ; a data cable  130 ; a power and data coupler  110 ; a network cable  160 ; a power and data decoupler  170 ; a network device  100 ; a telephone  190 ; an external power source  151 ; and, a power cable  121 . 
     The following describes the coupling of the elements of FIG.  1 . The external power source  150  couples to the power and data coupler  110  via the power cable  120 . The power cable  120  couples to the power and data coupler  110 . The communications network  140  transmits both computer data signals  103  and telephone data signals  102 . The communications network  140  couples to the data cable  130 . The data cable  130  couples to the power and data coupler  110 . The power and data coupler  110  also couples to the network cable  160 . The network cable  160  couples to the power and data decoupler  170 . The power and data decoupler  170  couples to the network device  100  and the telephone  190 . The external power source  151  couples to the power cable  121 . The power cable  121  couples to both the power and data decoupler  170  and to the network device  100 . 
     The following describes the elements in greater detail and describes how the elements act together. 
     The external power source  150  provides a power signal  105  to the power and data coupler  110 . Various embodiments of the invention use different external power sources  150 : such as, a computer&#39;s power supply, a battery, or a wall outlet and adaptor. What is important, however, is that there is some source of power that can eventually be supplied to the network device  100 . 
     In one embodiment, the power cable  120  is a standard two wire power cable. Other embodiments use other power transfer apparatuses to provide power to the power and data coupler  110 . For example, in one embodiment, the external power source and the power and data coupler  110  are included in a hub. 
     The communications network  140  is representative of many different types of communications networks supported by various embodiments of the invention. Example communications networks  140  include FDDI, ethernet (including ten Mbits/s, one hundred Mbits/s, and one Gigabits/s standards), ATM, token ring, and AppleTalk. However, what is important is that a data signal  104  is communicated between the communication network  140  and the network device  100 . Also, the communications network  140  transmits both computer data signals  103  and the telephone data signal  102 . 
     In one embodiment, the telephone data signal  102  includes the bearer portion of a telephone signal. The bearer data is, for example, the voice signal. In another embodiment, the telephone data signal includes additional data supporting functions such as caller ID and voicemail access. The telephone data signal  102  is formatted and transmitted in ethernet packets. These ethernet packets are formatted the same way as the ethernet packets for the computer data  103 . Thus, in this embodiment, the data signal  104  comprises ethernet packets. 
     The power and data coupler  110  will normally transmit the data signal  104 . However, when the power signal  109  is not available to power the telephone  190 , the power and data coupler  110  couples the power signal  105  with the data signal  104  to produce a combined power and data signal  107 . The power and data coupler  110  is described in greater detail below. What is important is that there is some combined power and data signal  107  that can eventually be supplied to the telephone  190 . 
     The network cable  160  includes one or more wires for transmitting the combined power and data signal  107 . In one embodiment, the network cable  160  includes an CAT-3 or CAT-5 twisted pair cable. 
     The network device  100  represents a class of devices supported by various embodiments of the invention. For example, in one embodiment, the network device  100  includes a network computer. In another embodiment, the network device  100  includes a personal computer having a network interface card. 
     The telephone  190  is coupled to the power and data decoupler  170  via the telephone cable  180 . The telephone  190  is representative of any of a number of telephones. Various embodiments of the invention include plain old telephone service telephones, telephones with PBX features (such as are available from Nortel, Rolm, and Lucent Technology). In some embodiments, the telephones  190  communicate analog telephone signals over the telephone cable  180 . In other embodiments, the telephone  190  communicates digital telephone signals over the telephone cable  180  (in these embodiments, the telephone  190  includes the digital to analog circuits for converting the users voice signal to and from a digital representation). The telephone cable  180 , in one embodiment, is a four wire telephone cable. In other embodiments, the telephone cable  180  includes two wire, six wire, or more, telephone cable. 
     The external power source  151  provides a power signal  109  to the network device  100  and to the power and data decoupler  170  via the power cable  121 . Various embodiments of the invention use different external power sources  151 : such as, a computer&#39;s power supply, a battery, or a wall outlet and adaptor. What is important, however, is that there is some source of power that is supplied to the network device  100  during normal operation. However, when the external power source  151  is not available, such as during a power outage or when the power cable  121  is not connected to the power and data decoupler  170 , the power from the combined data and power signal  170  can be used to power the telephone  190 . 
     The power and data decoupler  170  is responsible for supplying telephone data and power to the telephone  180 , and computer data to the network device  100 . The power and data decoupler  170  combines power, from some source, and the telephone data signals to produce the telephone power and data signal  108 . In normal operation, the power and data decoupler  170  combines the power signal  109  with a telephone data signal extracted the data and power signal  107 . (In this normal operation, the data and power signal  107  only includes data, not power.) When the power signal  109  is not available, the power and data decoupler  170  decouples the power signal  105  from the data signal  104 . The power and data decoupler  170  then couples the power signal with the telephone data signal to produce the telephone power and data signal  108 . By being able to continuously power the telephone allows the user to use the telephone, even when the external power source  151  fails. 
     The following describes the general operation of the elements of FIG. 1. A telephone data signal  102  is combined with a computer data signal  103  in the communications network  140 . The data signal  104  is communicated, via the data cable  130 , between the communications network  140  and the power and data coupler  110 . When the external power source  151  is supplying the power signal  109 , the power and data coupler  110  simply transmits the data signal onto the network cable  160  (in this situation, the power and data signal  107  does not include a power signal). The power and data decoupler  170  receives the power and data signal  107  and extracts the telephone data signal and the computer data signal  106 . The computer data signal  106  is communicated with the network device  100 . The power and data decoupler  170  couples the power signal  109  with the telephone data signal and transmits the combined telephone power and data signal  108  to the telephone  190 . However, when the external power source  151  is not supplying the power signal  109 , the power and data coupler  110  couples the power signal  105  to the data signal  104 . In this situation, the decoupler  170  decouples the power signal from the power and data signal  107 . The decoupler  170  still extracts the telephone data and computer data signal  106 . (If the network device  100  is not powered, however, the network device  100  will not be processing the computer data signal  106  that does not include the bearer data.) The decoupler  170  then couples the extracted telephone data and the decoupled power signal to create the telephone power and data signal  108  for use by the phone  190 . Note that even if the external power source  151  is not working, the telephone  190  will continue to work. 
     Network Devices Using Power Transfer Apparatuses 
     FIG. 2 is an overview of a power transfer apparatus for use with network devices including computers. The following lists the elements in FIG.  2  and then describes those elements. 
     FIG. 2 includes the following elements: a PBX  242 ; a network server  240 ; a network  243 ; a hub  245 ; an external power source  150 ; a power outage coupler  200 ; a power outage coupler  202 ; a coupler  204 ; a network cable  260 ; an external power source  151 ; a power cable  220 ; a computer  280 ; a telephone  290 ; a network cable  262 ; an external power source  152 ; a power cable  222 ; a network computer  282 ; a telephone  292 ; a telephone cable  281 ; a network cable  264 ; a network computer  284 ; a telephone  294 ; and, a telephone cable  283 . 
     The PBX  242 , the network server  240  and the network  243 , work together to provide both telephone data and network data to devices coupled to the network  243 . The PBX  242 , the network server  240  and the network  243  represent are example devices that provide the telephone functions, network server functions and network functions, respectively. In one embodiment, the PBX  242  includes a PBX having functions similar to a PBX from, for example, Nortel, Rolm, Lucent Technology, or Seimens. However, the PBX  242  has been modified to allow the network server  240  to send the PBX  242 &#39;s telephone signal data  102  as ethernet packets. Various embodiments of the invention include network servers  240  from, for example, Compaq, Hewlett-Packard, IBM, and Sun Microsystems. The network server  240  acts as a server for the network and includes circuitry and software for communicating with the PBX  242 . In one embodiment, the network server supports ethernet protocols for communicating data onto the network  243 . The network  243  is illustrative of any of a number of computer networks including ethernet, FDDI, AppleTalk, Token Ring, and ATM. 
     Note, in another embodiment, the PBX  242  is replaced with a PBX process running in the network server  240  and a gateway. A gateway provides the connection to the public switching network for the network  243 . Vienna Systems, Corporation, of Kanata, Ontario, Canada, provides such a gateway. 
     The hub  245  couples to the network  243  and allows network devices to communicate with the network  243 . Each device couples to a different port on the hub  245 . For example, in FIG. 2, each coupler couples to a different port on the hub  245 . In one embodiment, the hub  245  is not needed to supply the data signal. Therefore, in these embodiments of the invention, the data signal is supplied by a network computer, a router, a switch, and/or a bridge. 
     The external power source  150  provides power to the couplers. Each coupler, in this example, has a potentially different power requirements, therefore, different external power sources may be used. For example, to power the power outage coupler  200 , an adapter can be used. The adapter steps down the available electrical power from 117 or 220 volts AC to an AC or DC voltage that is high enough to provide adequate voltage for the telephone  290 . In one embodiment, the power adaptor supplies an output voltage of approximately forty-eight volts. Similar, example power adapters are described in U.S. patent application Ser. No. 08/865,016, filed on May 29, 1997, entitled, “Power Transfer Apparatus for Concurrently Transmitting Data and Power Over Data Wires,” having inventors David A. Fisher, Lawrence M. Burns, and Stephen Muther. 
     The couplers (power outage coupler  200 , power outage coupler  202 , and power outage coupler  204 ) provide similar coupling functions as those found in power and data coupler  110 . Each coupler couples power and data signals for use by a telephone and some other computing device. The amount of power coupled, and when the power is coupled, is what varies between the various couplers. This will be described in greater detail below. Importantly, these couplers, and the present configuration, is merely illustrative. In some embodiments of the invention, each coupler has the same functionality. 
     Note that in other embodiments, the hub  245  includes the couplers and the external power source  150 . 
     The following describes three example power and data coupling systems corresponding to coupler  200 , coupler  202 , and coupler  204  respectively. Each of these systems will now be described. 
     The following describes the system associated with the coupler  200 . The coupler  200  is coupled to the computer  280  via the network cable  260 . The external power source  151  couples to the computer  280  via the power cable  220 . The telephone  290  couples to the computer  280 . Comparing this system to FIG. 1, the computer  280  is the network device  100 , and the computer  280  includes the power and data decoupler  170 . When the external power source  151  fails, or otherwise becomes incapable of supplying power to the telephone  290 , the power and outage coupler  200  is notified to couple power with the data signal from the hub  245 . The power and data decoupler  170 , in the computer  280 , can then switch the source of power from the external power source  151  to the power from the network cable  260 . This system is described in greater detail below with respect to FIG.  3 . 
     The following describes the system associated with the coupler  202 . The coupler  202  is coupled to the network computer  282 . The external power source  152  couples to the network computer  282  via the power cable  222 . The telephone  292  couples to the network computer  282  via the telephone cable  283 . The network computer  282  includes a power and data decoupler similar to the one in the system of FIG.  1 . The power outage coupler  202 , and corresponding power and data decoupler, operates in a similar manner as the power outage coupler  200  system, except that the power outage coupler  202  supplies sufficient power to the decoupler to power both the telephone and the network computer  282 . In one embodiment, separate power signals (e.g., twenty-four volts DC and forty-eight volts DC) are supplied on different pairs of wires within the network cable  262 . The decoupler decouples both these power signals from any data signals. The different power signals are for the different power needs of the telephone  292  and the network computer  282 . In another embodiment, only one power signal is transmitted, which is then modified by the decoupler for use by the network computer  282  and the telephone  292 . 
     The following describes the system associated with the coupler  204 . The coupler  204  is coupled to the network computer  284  via the network cable  264 . The coupler  204  is similar to the power outage coupler  202 , but the coupler  204  constantly supplies the power for the network computer  284  and the telephone  294 . 
     In another embodiment of the invention, the decoupler  170  is included in a telephone  190 . In this embodiment, the telephone couples directly to a coupler such as coupler  204  and no computer is needed. In one embodiment where the telephone includes the decoupler, the telephone couples to a hub. The hub includes the coupler. The ethernet packets passed from the hub to the telephone include only bearer data. In another embodiment, the ethernet packets include additional data for controlling the telephone. Such data includes other telephone data such as caller ID information, requests to the PBX  242 , and the like. In another embodiment, the data also includes computer data for a computer built into the telephone. 
     In another embodiment of the invention, the telephone includes the decoupler  170  and has network infrastructure functions, such as repeater functions. This allows the telephone to forward any packets it receives to any additional network devices that are downstream from the telephone. 
     In another embodiment, the telephone has its own external power supply, such as a battery or a wall adapter. The coupler couples a power signal to the network cable  160  when the telephone&#39;s power supply fails. 
     Schematic Diagram of a Power Transfer Apparatus 
     FIG. 3 is a schematic diagram of a power transfer apparatus that supports telephone features. This apparatus corresponds to the system associated with the coupler  200  in FIG.  2 . The following first lists the elements in FIG. 3, then describes the elements&#39; couplings, and then describes the elements&#39; interactions. 
     FIG. 3 includes the power cable  322 , the data cable  130 , a power outage coupler  200 , the network cable  260 , the computer  280 , the telephone  290 , the telephone cable  281 , the external power source  151 , and the computer power cable  220 . The computer  280  includes a network interface card (NIC)  300 , a processor subsystem  330 , and a power subsystem  340 . The NIC  300  includes a power outage decoupler  370 , a network interface and telephony circuit  320 , a power source switch  390 , and a telephone coupler  345 . 
     The elements of FIG. 3 are coupled as follows. The power cable  322 , the data cable  130 , and the network cable  260  are coupled to the power outage coupler  200  in the same way as shown in FIG.  1 . The network cable  260  also couples to the input port of the power outage decoupler  370  on the NIC  300 . The data output port of the decoupler  370  couples to the network interface and telephony circuit  320 . The computer data port of the network interface and telephony circuit  320  couples to the processor subsystem  330 . The power output port of the decoupler  370  couples to one of the two inputs of the power source switch  390 . The other input of the power source switch  390  is coupled to the power subsystem  340 . The power subsystem  340  also couples to the processor subsystem  330  and to the external power source  151  (via the computer power cable  220 ). The output of the power source switch  390  couples to the power input ports of the network interface and telephony circuit  320  and the telephone coupler  345 . The telephone data port of the network interface and telephony circuit  320  is coupled to the data input port of the telephony coupler  345 . The output of the telephone coupler  345  is coupled to the telephone cable  281 . The telephone cable  281  couples to the telephone  290 . 
     The following describes the elements and interactions between the elements of FIG.  3 . The power subsystem  340  is illustrative of a PC power supply. The power subsystem  340  generally provides the power for the computer  280 , including the processor subsystem and the NIC  300 . The processor subsystem  330  represents those elements of the computer  280  that are not directly involved with the network interface functions of the computer  280 . The NIC  300  includes the elements to perform three main functions. Each of these functions will now be described. 
     First, the NIC  300  supports network interface services, such as ethernet communications, for the computer  280 . In one embodiment, these services are supported using an ethernet communications circuit in the network interface and telephony circuit  320 . 3COM Corporation, of Santa Clara, Calif., supplies such circuits. 
     Second, the NIC  300  also provides telephony services for the telephone  290 . As the network interface and telephony circuits  320  receives data from the power outage decoupler  370 , the network interface and telephony circuits  320  extracts telephony related data and reformats it for use by the telephone. In one embodiment, this includes providing digital telephone data to the telephone coupler  345 . The telephone coupler  345  then converts the digital telephone data to an analog signal and combines this analog signal with the power from the power source switch  390 . In one embodiment, the telephone coupler  345  includes circuits similar to those found in a PBX, or in a telephone for use with a PBX. In another embodiment, the telephone  345  includes circuits similar to those found in a line card at a central switching office for coupling power and data together. 
     Third, the NIC  300  switches between the available power supplies. The power source switch  390  will attempt to use the power from the subsystem  340 . However, if a power outage prevents the power subsystem  340  from supplying sufficient power to power the telephone, the power supply switch  340  will switch to using the network power signal  305 . In one embodiment, the network interface card will signal the power outage coupler  200  to begin supplying power because of the insufficient computer power signal  303 . 
     Note that the examples described above are merely illustrative. Other embodiments of the invention include different configurations and elements. For example, in one embodiment of the invention, some of the circuits in the power source switch  390  are shared by the power outage decoupler  370  and the telephone coupler  345 . In another embodiment, the power outage coupler  200 , the power outage decoupler  370 , and/or the telephone coupler  345  include electrical isolation circuitry. Examples of such circuitry are described in U.S. patent application Ser. No. 08/865,016, filed on May 29, 1997, entitled, “Power Transfer Apparatus for Concurrently Transmitting Data and Power Over Data Wires,” having inventors David A. Fisher, Lawrence M. Burns, and Stephen Muther. In another embodiment, the power coupled by the coupler  200  is an AC power signal, while in another embodiment, the power coupled by the coupler  200  is a DC power signal. 
     The preceding has described multiple embodiments of the invention. In one embodiment, power, computer data and telephone data are combined and transmitted to a computer. The computer uses the power to power a telephone coupled with the computer. Because the power and data are combined, the telephone can be powered even when the computer has been powered off. 
     While the foregoing invention has been described in referenced to some of its embodiments, it should be understood that various modifications and alterations will occur to those practiced in the art. Such modifications and alterations are intended to fall within the scope of the appended claims.