Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells – With individual charging of plural batteries or cells
Reexamination Certificate
2000-05-30
2001-06-05
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
With individual charging of plural batteries or cells
C320S139000
Reexamination Certificate
active
06242888
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to battery charging methods and apparatus and, more particularly, relates to battery chargers operating with a pulse width modulator (PWM) for simultaneously charging a first battery and a second battery, wherein either the first battery or the second battery is installed within a battery-powered device, such as a communication user terminal including cellular telephones and personal communicators.
BACKGROUND OF THE INVENTION
Referring to
FIG. 1
, it is known to provide a desktop battery charger station
1
having a first slot
2
, sometimes referred to as a “front-slot”, for receiving a cellular telephone
6
and a second slot
3
, sometimes referred to as a “back-slot”, for receiving just a battery module or pack
5
of the cellular telephone. In this manner the user is enabled to recharge the battery pack that is currently installed within the phone
6
by inserting the base of the phone
6
into the first slot
2
, while a spare battery pack
5
is installed within the second slot
3
. A connection
4
is provided for coupling the charger station
1
to a source of electric power. The charger station
1
can contain a PWM circuit for selectively applying charging pulses to the phone's battery pack and to the back-slot battery pack. Alternatively, PWM signals can be obtained from the charging circuitry (CC)
7
contained within the phone
6
. Some phones are also known that contain a switch (SW) in series with the battery, where the switch is opened and closed by the charging circuit
7
at, for example, a 1 Hz rate. When the switch is closed the charger
1
provides current to the battery, and when the switch is opened no current is drawn from the battery of the phone
6
.
It is not required that both slots
2
and
3
be used simultaneously, as one slot or the other could be used at any given time.
However, this arrangement is not always optimum, as the conventional operation shares the charger station
1
by defining a charging time slot for the phone's slot
2
, and another time slot for the back-slot
3
battery pack. For example, if a phone is installed having a discharged battery pack then the charger station
1
will operate so as to direct all charging energy to the first slot
2
until such time that the phone's battery pack is detected as nearing or obtaining full charge. Referring to
FIG. 2
, this first charging period (referred to as a time slot for the phone
6
) will contain a number of charging pulses. However, during this time no charging pulses and charging energy are directed to the back-slot
3
. Charging energy is applied to the back-slot
3
only after the phone's recharged battery reaches a maintenance or trickle charge state, also referred to as a charger idle state. This second charging period is referred to in
FIG. 2
as the time slot for the back-slot battery
5
.
Referring now as well to
FIG. 3
, for a given PWM pulse it can be seen that there is a charger active period (defining some percentage of the charger current that is used) followed by charger inactive period (defining some percentage of the charger current that is not used). As the pulse width of the charger active period decreases the charger voltage decreases, typically down to some minimum specified voltage level, and consequently decreases the current that flows from the charger station
1
to the battery of the phone
6
. Conversely, as the pulse width of the charger active period increases the charger voltage also increases up to, potentially, some maximum specified voltage level, as does the current flowing from the charger station
1
to the battery of the phone
6
.
It can be appreciated that this results in wasted charging time, as the period between charging pulses (shown as a horizontal bar in FIG.
2
and as the charger inactive period in
FIG. 3
) is not used for charging any battery in either the phone's front-slot
2
or the spare battery back-slot
3
.
As high speed data and other services begin to be supported by cellular telephones and personal communicators, their power consumption will increase as well, thereby necessitating the consumption of more battery power and hence more frequent battery charging cycles.
For example, before leaving the home or office a user may wish to recharge his phone's battery pack, as well as a spare battery pack for the phone. As can be appreciated, it is desirable for this recharging operation to be accomplished as quickly as possible so as not to delay the user's departure.
OBJECTS AND ADVANTAGES OF THE INVENTION
It is a first object and advantage of this invention to provide an improved battery charger station and method for operating same that overcomes the foregoing and other problems.
It is another object and advantage of this invention to provide a dual charger battery charger station that operates to simultaneously recharge a battery pack installed within a mobile communication device and at least one other battery pack.
It is a further object and advantage of this invention to provide a dual charger battery charger station that is responsive to a composite PWM signal output from a battery powered mobile communication device, to recharge a battery pack installed within the mobile communication device and at least one other battery pack.
SUMMARY OF THE INVENTION
The foregoing and other problems are overcome and the objects of the invention are realized by methods and apparatus in accordance with embodiments of this invention.
A battery charging station in accordance with the teachings herein includes a first charging circuit for charging a first battery, a second charging circuit for charging a second battery and circuitry that is responsive to a pulse width modulated (PWM) signal that defines a plurality of repeating charging periods, for selectively allocating, during a single one of the charging periods, battery charging energy first to one of the first charging circuit or the second charging circuit, and then to the other charging circuit. The PWM signal is preferably received from an external battery charging circuit associated with the first battery, and during a single one of the charging periods the battery charging energy is applied first to the first charging circuit and then, if at least one criteria is met, to the second charging circuit. The at least one criteria can include an amount of remaining charging energy capacity within a current charging period after applying charging energy to the first battery, and more preferably includes an ability to develop a minimum charging voltage to the second battery within the current charging period, after applying charging energy to the first battery.
In a presently preferred embodiment of these teachings the first battery is installed within a battery powered device, such as a cellular telephone or a personal communicator, and the PWM signal is received from a battery charging circuit installed within the battery powered device. The second battery is located within a (spare) battery pack that is installable within the same or a different battery powered device. During a single one of the charging periods the battery charging energy can be applied first to the first charging circuit for recharging the first battery and then selectively applied to the second charging circuit for recharging the second battery.
More specifically, the total available current from the charger during a single one of the charging periods can be selectively allocated for charging the battery of a phone, as specified by the PWM circuit of the phone, and any remaining current can be used to charge the back-slot battery.
Also disclosed is a method for operating a battery charging station that includes steps of: (A) providing a first charging circuit for charging a first battery and a second charging circuit for charging a second battery; and (B) electrically coupling a first battery to the first charging circuit and a second battery to the second charging circuit, the first battery being associated with a pulse
Nokia Mobile Phones
Ohlandt Greeley Ruggiero & Perle LLP
Toatley , Jr. Gregory J.
Tso Edward H.
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