Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1998-02-09
2001-07-03
To, Doris H. (Department: 2682)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S575100, C455S090300, C455S462000, C455S557000, C379S433020
Reexamination Certificate
active
06256519
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to cordless telephones, and more particularly to a cordless telephone which includes an alternative configuration for use without power to a base unit.
2. Background of Related Art
Cordless remote telephones are popular consumer devices which allow a user in a home or office the freedom to stray hundreds or even thousands of feet from a base unit. Initially, the handsets of cordless telephones communicated with their base unit using analog signals. In more recent years, advancements have been made with respect to cordless telephones allowing digital communications between the handset and its base unit.
With the advancement in technology of cordless telephones, processors such as digital signal processors or microprocessors have been included within the base unit and/or the handset of a cordless telephone. The processors provide the cordless telephone with a vast array of features, but require a power source to operate.
Since the early days of telephones, a small amount of power has typically been provided on a telephone line by a central office for use by a telephone (customer premises equipment) connected to the telephone line. The power was typically used by the central office to sense on- and off-hook conditions, and by the user as a byproduct, e.g., to illuminate the telephone dial or keypad, and/or to bias a microphonic device, and/or to power a dual tone, multiple frequency (DTMF) device at the customer premises equipment. Even though the power provided by the telephone central office may be sufficient to power some conventional telephone devices such as standard wired handsets, there is nevertheless generally insufficient current available within regulatory guidelines to power the components of a cordless telephone. Thus, cordless telephones have generally and conventionally required external power sources.
The power source for a base unit of a cordless telephone typically is general household current, e.g., 120 volts AC, 50-60 Hz in the United States. The handset of the cordless telephone is typically powered by a battery. In most cases, the externally powered base unit also provides charging power for the battery in the handset when coupled with the base unit.
For all the advantages provided by the use of processors, RF transceivers and/or other externally powered devices, a conventional cordless telephone is nevertheless rendered useless during a power failure.
For instance, power may be removed from the base unit when severe weather conditions knock power lines to the home or office out of service. In such conditions, it may be desirable to utilize the telephone, particularly in emergency or life threatening situations. Without power, the conventional cordless telephone is incapable of placing or receiving telephone calls.
FIG. 4
depicts a conventional cordless telephone including a base unit
400
and a handset
450
. The base unit
400
and the handset
450
each include a respective antenna
414
,
466
for use in transmitting a radio frequency (RF) signal therebetween.
The base unit
400
includes a telephone line interface (TLI)
410
and cable
412
(e.g., including an RJ-11 telephone jack) for interconnection with a central office via a standard wall jack or the like. Although available, the conventional base unit typically does not draw a significant amount of power from the telephone line for powering devices therein. Of course, power is drawn from the telephone line to provide proper DC and AC characteristics to the central office. However, an external AC power source is utilized to power the components of the conventional cordless telephone.
A standard power cable
402
provides standard AC power to an alternating current (AC)-to-direct current (DC) converter
404
. AC/DC converter
404
converts power from the external power source into DC power for use by a processor
408
, RF transceiver
406
, and other externally powered devices within the base unit
400
. If the telephone line interface (TLI)
410
(otherwise known as a hybrid) is an active device, then it too is powered by the AC-to-DC converter
404
. The AC/DC converter
404
is typically protected by a diode
407
or other isolating device.
A conventional handset
450
typically includes, besides antenna
466
, an RF transceiver
454
, a processor
456
such as a DSP, microcontroller or microprocessor, an analog-to-digital (AND) converter
458
, and a digital-to-analog (D/A) converter
460
, all powered by a battery pack
452
. A microphone
462
provides an analog signal to the A/D converter
458
, and a speaker
464
outputs an analog signal from D/A converter
460
. A conventional 12 or 16-key keypad
467
allows direct user input and standard operation of the cordless telephone
During normal operation, the base unit
400
communicates with its handset
450
using a processed RF signal transmitted between antennae
414
,
466
. Unfortunately, as discussed above, a power failure will render the conventional base unit
400
virtually useless because the RF transceiver
406
and the DSP
408
will not be operational for lack of power. This is not a desirable situation, and in emergency situations may be life threatening if a separate, non-cordless telephone is not available. This causes the need to maintain an entirely separate corded telephone in another location in the home or office, whether or not a cordless telephone is also in service.
There is a need to provide a cordless telephone which has the ability, particularly in emergency situations, to be operated even when power is removed from the base unit.
SUMMARY OF THE INVENTION
In accordance with the principles of the present invention, a handset of a cordless telephone comprises both an RF transceiver and a telephone line interface. An audio module is adapted for communication with either the RF transceiver or the telephone line interface.
REFERENCES:
patent: 4752949 (1988-06-01), Steinbeck et al.
patent: 5010565 (1991-04-01), Nash et al.
patent: 5105460 (1992-04-01), Williams
patent: 5528667 (1996-06-01), Steffensen et al.
patent: 5596626 (1997-01-01), Nakayama
patent: 5758289 (1998-05-01), Lipp et al.
patent: 6002937 (1999-12-01), Young et al.
patent: 6036086 (2000-03-01), Sizer, II et al.
Bollman William H.
Lucent Technologies - Inc.
To Doris H.
LandOfFree
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