Telephonic communications – Subscriber line or transmission line interface – Power supply
Reexamination Certificate
2000-11-09
2004-10-12
Kuntz, Curtis (Department: 2643)
Telephonic communications
Subscriber line or transmission line interface
Power supply
C379S307000, C379S322000, C379S323000
Reexamination Certificate
active
06804351
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for detecting the presence of a connected device of a particular class, such as a telephone that may require phantom power to be supplied over twisted pair wiring.
BACKGROUND OF THE INVENTION
Telephones and other types of data terminal equipment (DTE) are routinely used for voice data and other forms of telecommunication. Examples of these include voice communication devices or telephones operating through a private branch exchange (PBX) or key telephone system. PBX-type and key telephone system-type telephones typically require the application of external electrical power in order to operate. The power is used to energize circuits within the telephone circuitry, such as processing displays, etc.
There are essentially two practical methods available for powering such telephones. The first method provides power directly to the telephone. This may be accomplished by a wall-mounted transformer providing a direct current (DC) or alternating current (AC) low voltage power supply to the telephone from the electric power grid. Such direct power methods have a number of drawbacks. Apart from continuous occupation of a potentially scarce electrical outlet, during a power grid disruption, the power to the telephone may be disconnected rendering the telephone inoperative and effectively precluding emergency telephone usage during the black out.
The second method for providing telephone power involves supplying so-called “phantom power” by coupling a power signal (typically up to about 48 volts DC) to the telephone over twisted pair lines as taught, for example, in U.S. Pat. No. 6,115,468 entitled “Power Feed for Ethernet Telephones via Ethernet Link”. In accordance with a specific embodiment of the aforementioned patent, as illustrated in
FIG. 1
hereof, a system
10
including a plurality of data ports
12
,
14
and
16
within a communication device such as a switch
18
is provided to transmit data on lines
20
and
22
,
24
and
26
, and
28
and
30
to and from first, second and third load devices
32
,
34
and
36
, respectively. Load devices
32
,
34
and
36
may be associated with Ethernet telephones and/or other Ethernet devices
38
,
40
and
42
respectively, requiring power to be transmitted to them in addition to data over Ethernet twisted pair lines.
Turning to the first port
12
in
FIG. 1
as an example, data on lines
22
and
20
are provided to transmitter
44
and from receiver
46
, respectively. Transmitter
44
drives data traffic along pair
48
, while receiver
46
receives data from pair
50
. First transformer
52
includes a first primary
54
connected to pair
48
, and a second primary
56
connected to pair
50
.
A similar arrangement exists at first load
32
. Second transformer
58
includes a first secondary
60
and a second secondary
62
. These are respectively connected to pairs
64
and
66
that are, respectively, connected through receiver
68
and transmitter
70
to load device
32
. Ethernet link
72
couples first and second secondaries
74
and
76
of first transformer
52
to first and second primaries
78
and
80
of second transformer
58
. Ethernet link
72
preferably comprises a pair of twisted pair conductors
82
a
and
82
b
, wherein twisted pair
82
a
connects first secondary
74
to first primary
78
and twisted pair
82
b
connects second secondary
76
to second primary
80
.
Power coupling may be provided as follows: Secondaries
74
and
76
of first transformer
52
each include a center tap
84
and
86
respectively. Center tap
84
connects to the positive lead
88
of a power supply
90
, and center tap
86
connects to the negative lead
92
of power supply
90
, which may, preferably, include an uninterruptible power supply (UPS). DC filtering components
94
a
,
94
b
and
94
c
may be provided as well known to those of ordinary skill in the art. Now the entire loop of twisted pair
82
a
is at the potential of positive lead
88
while the entire loop of twisted pair
82
b
is at the potential of negative lead
92
without any impact on data transmission. A power processor
96
may preferably be attached to center taps
98
and
100
of first and second primaries
80
and
82
of second transformer
58
, respectively, so as to provide a DC power source to the power processor
96
.
The power processor
96
, shown in more detail in
FIG. 2
, conventionally includes a filter
102
, a rectifier
104
, a filter capacitor
106
and a DC-DC converter
108
. Other similar arrangements are also well known to those of ordinary skill in the art. The power processor
96
may perform DC-DC power conversion and filtering required, as well as provide power over leads
110
and
112
to load
32
, which may be an Ethernet telephone or other device.
Returning to
FIG. 1
, the communication system
10
may be divided into a switch
18
and DTE devices
38
,
40
and
42
. The switch
18
may be found within a telephone equipment room, for example. Cables may then be routed from the load devices
32
,
34
and
36
to the switch
18
for connecting to conventional jacks or connectors of the switch (not shown) such as the well-known type RJ-45 connectors (as used herein the term RJ-45 type connector is intended to include both make (plugs) and female (sockets) variants thereof). Because the switch
18
supplies a DC bias to the center taps
84
and
86
, and because the switch
18
may conceivably be used with legacy DTE potentially not compatible with the application of such a voltage, it would be desirable to provide a mechanism for detecting which ports of such a switch
18
, should and should not have phantom power applied. Phantom power should then be supplied to a DTE if the switch establishes that the DTE is a compatible IP telephone or other compatible powerable network device. However, a priori determination of this condition is not presently available, and thus a requirement for power at the DTE cannot presently be determined. Accordingly, there exists a need for an efficient, simple and inexpensive method and apparatus for detection of a compatible IP device that should be provided with phantom power.
SUMMARY OF THE INVENTION
A method and an apparatus provide for determining whether a data terminal equipment (DTE) device represents a compatible device lacking an independent power supply and adapted to be powered using phantom power over a wired connection from a communications device such as a switch. A detection signal may be transmitted from the communications device to an identity network connected to the DTE. A response detection signal may be returned and checked in a receiver at the communications device. A switch may then be closed to provide phantom power if the result of the check indicates that the DTE is a compatible device adapted to receive phantom power. Compatible DTE devices may include telephones, Voice over IP (VoIP, or IP or Ethernet) telephones, network access devices, computers and the like.
REFERENCES:
patent: 5034948 (1991-07-01), Mizutani et al.
patent: 5089927 (1992-02-01), Bulan et al.
patent: 5148144 (1992-09-01), Sutterlin et al.
patent: 5406260 (1995-04-01), Cummings et al.
patent: 5799040 (1998-08-01), Lau
patent: 5991885 (1999-11-01), Chang et al.
patent: 6218930 (2001-04-01), Katzenberg et al.
patent: 6246748 (2001-06-01), Yano
patent: 6366143 (2002-04-01), Liu et al.
patent: 6535983 (2003-03-01), McCormack et al.
patent: 6541878 (2003-04-01), Diab
Cisco Technology Inc.
Kuntz Curtis
Pham Tuan
Ritchie David B.
Thelen Reid & Priest LLP
LandOfFree
Method and apparatus for detecting a compatible phantom... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for detecting a compatible phantom..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for detecting a compatible phantom... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3269242