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Mobile Phone Patent Abstract
A mobile phone battery pack has a body housing a plurality of rechargeable
battery cells and an energy storage device for electrical connection
to said mobile phone. A switch connects the energy storage device
to the battery cells. A microprocessor-based controller periodically
closes the switch to enable charging of the energy storage device
by the battery cells and opens the switch to disconnect the battery
cells and to enable discharging of the energy storage device to
power the mobile phone in a standby mode.
Mobile Phone Patent Claims
What is claimed is:
1. A battery pack for a mobile phone, which battery pack comprises
a body, a plurality of rechargeable battery cells and an energy
storage device provided within the body for electrical connection
to said mobile phone, a switch connecting the energy storage device
to the battery cells, a microprocessor-based controller for operating
the switch in a first state to enable charging of the energy storage
device by the battery cells and in a second state to enable discharging
of the energy storage device to power said mobile phone, and a sensor
provided for the controller to monitor the charging condition of
the energy storage device and, in response, to maintain the charging
condition of the energy storage device by operating the switch relatively
longer or more frequently in the first state than in the second
state.
2. A battery pack as claimed in claim 1, wherein the switch is
closed in the first state and open in the second state.
3. A battery pack as claimed in claim 1, wherein the controller
is adapted to operate the switch alternately between the first and
second states.
4. A battery pack as claimed in claim 1, wherein the switch in
the second state is arranged to disconnect the battery cells from
said mobile phone.
5. A battery pack as claimed in claim 1, wherein the energy storage
device is provided by a capacitor.
6. A battery pack as claimed in claim 1, wherein the energy storage
device is provided by a rechargeable battery cell.
7. A battery pack as claimed in claim 1, including a voltage step-up
device connected to the battery cells for, under the control of
the controller, stepping up the voltage of the battery cells supplied
to said mobile phone.
8. A battery pack as claimed in claim 7, wherein the voltage step-up
device includes a step-up transformer for stepping up the voltage
of the battery cells supplied to said mobile phone.
9. A battery pack as claimed in claim 7, wherein the voltage step-up
device includes a capacitor for smoothing the stepped-up voltage.
10. A battery pack as claimed in claim 7, wherein the voltage step-up
device includes a transistor which is to be switched on and off
by the controller to extract power from the battery cells.
11. A battery pack for a mobile phone, which battery pack comprises
a body, a plurality of rechargeable battery cells and an energy
storage device provided within the body for electrical connection
to said mobile phone, a switch connecting the energy storage device
to the battery cells, and a microprocessor-based controller for
operating the switch in a first state to enable charging of the
energy storage device by the battery cells and in a second state
to enable discharging of the energy storage device to power said
mobile phone, wherein the battery cells are arranged to be connected
to said mobile phone by a first path comprising the switch and by
a second path comprising a second switch which is also to be operated
by the controller, said first path being provided for the battery
cells to supply power to the energy storage device and said mobile
phone for operation in a standby mode, said second path being provided
for the battery cells to supply power to only said mobile phone
for operation in a busy mode.
12. A battery pack as claimed in claim 11, wherein the energy storage
device is arranged to be connected to said mobile phone via a uni-directional
element which forms part of the first path.
Mobile Phone Patent Description
The present invention relates to a rechargeable battery pack for
mobile phones, said battery pack having a prolonged operating time
per recharging.
SUMMARY OF THE INVENTION
According to the invention, there is provided a battery pack for
a mobile phone, which battery pack comprises a body, a plurality
of rechargeable battery cells and an energy storage device provided
within the body for electrical connection to said mobile phone,
a switch connecting the energy storage device to the battery cells,
and a microprocessor-based controller for operating the switch in
a first state to enable charging of the energy storage device by
the battery cells and in a second state to enable discharging of
the energy storage device to power said mobile phone.
Preferably, the switch is closed in the first state and open in
the second state.
It is preferred that the controller is adapted to operate the switch
alternately between the first and second states.
Preferably, the switch in the second state is arranged to disconnect
the battery cells from said mobile phone.
In a preferred embodiment, a sensor is provided for the controller
to monitor the charging condition of the energy storage device and,
in response, to maintain the charging condition of the energy storage
device by operating the switch relatively longer or more frequently
in the first state than in the second state.
Preferably, the battery cells are arranged to be connected to said
mobile phone by a first path comprising the switch and by a second
path comprising a second switch which is also to be operated by
the controller.
More preferably, the energy storage device is arranged to be connected
to said mobile phone via a uni-directional element which forms part
of the first path.
It is preferred that the first path is provided for the battery
cells to supply power to the energy storage device and said mobile
phone for operation in a standby mode, and the second path is provided
for the battery cells to supply power to only said mobile phone
for operation in a busy mode.
The energy storage device may be provided by a capacitor or a rechargeable
battery cell.
In a preferred embodiment, the battery pack includes a voltage
step-up device connected to the battery cells for, under the control
of the controller, stepping up the voltage of the battery cells
supplied to said mobile phone.
Preferably, the voltage step-up device includes a step-up transformer
for stepping up the voltage of the battery cells supplied to said
mobile phone.
Preferably, the voltage step-up device includes a capacitor for
smoothing the stepped-up voltage.
Preferably, the voltage step-up device includes a transistor which
is to be switched on and off by the controller to extract power
from the battery cells.
The invention will now be more particularly described, by way of
example only, with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an embodiment of a battery pack,
for use on a mobile phone, in accordance with the invention; and
FIG. 2 is a schematic circuit diagram of the battery pack of FIG.
1.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT(S)
Referring to the drawings, there is shown a rechargeable battery
pack 10, embodying the invention, for use on a standard personal
mobile phone 100, which battery pack 10 has a body 11 and a series
of five rechargeable battery cells 12 and internal operating circuitry
20 both housed within the body 10. The battery pack 10 is designed
to releasably fit against the rear side of the mobile phone 100
with respective contact terminals in electrical connection, as generally
known in the art. In use, the negative terminals of the mobile phone
100 and the battery cells 12 are connected together at a common
ground G.
The operating circuitry 20 has first and second switches 21 and
22 which are provided in respective paths running in parallel with
each other for connecting the positive terminal of the battery cells
12 to that of the mobile phone 100. The second switch 22 is connected
right across the battery cells 12 and the mobile phone 100. The
first switch 21 is connected in series with a resistor R and a diode
D1 leading to the mobile phone 100. A first circuit node N1 is formed
between the switch 21 and the resistor R. A second circuit node
N2 is formed between the resistor R and the diode D1. A capacitor
C1 is connected across the circuit node N2 and the ground G. A third
circuit node N1 is formed between the diode D1 and the mobile phone
100.
The operating circuitry 20 includes a microprocessor-based control
chip 23 and a pair of sensors 24 and 25. The control chip 23 controls
the operation of the switches 21 and 22 via respective output pins
21P and 22P. The first sensor 24 is a current sensor which has two
inputs connected to the circuit nodes N1 and N2, respectively, and
an output connected to an input pin 24P of the control chip 23,
for enabling the control chip 23 to monitor the current flowing
through the resistor R. The second sensor 25 is a voltage sensor
which has two inputs connected to the circuit node N2 and the ground
G, respectively, and an output connected to an input pin 25P of
the control chip 23, for enabling the control chip 23 to monitor
the voltage developed across the terminals of and hence the charging
condition of the capacitor C1.
The mobile phone 100 has two normal operating modes, namely standby
and busy modes. In the standby mode, the mobile phone 100 communicates
periodically with the nearest transmission station for the purpose
of, inter alia, identifying its physical location in terms of the
communication zone that it is in and looking for a calling signal.
The mobile phone 100 requires a current of about 30-50 mA from the
battery cells 12 in the standby mode. In the busy mode, the mobile
phone 100 transmits and receives speech signals to and from the
nearest transmission station for a phone user to talk to a caller.
The mobile phone 100 requires a current of about 270-300 mA from
the battery cells 12 in the busy mode. In normal use, the mobile
phone 100 operates in the standby mode for most of the time and
changes into the busy mode when a call is received or made.
The battery cells 12 are connected in series to provide an operating
voltage which is normally 6 V and, in a fully charged condition,
may reach up to 6.5 V. The mobile phone 100 requires a minimum operating
voltage of 4.5 V to 5 V in the standby mode and a relatively higher
operating voltage in the busy mode. In the fully charged condition,
the battery cells 12 supply excessive power to the mobile phone
100 than what the phone normally requires in the standby mode. This
is particularly the case during the initial, for example, four hours
of battery operation and results in a waste of battery power.
The first switch 21 is provided for use when the mobile phone 100
operates in the standby mode, whereas the second switch 22 overrides
the first switch 21 when the mobile phone 100 operates in the busy
mode. The control chip 23 is programmed to continuously provide
a square-wave control signal (waveform A) at its pin 21P for periodically
turning on and off the first switch 21, said control signal having
a frequency of at least 5-10 kHz. The second switch 22 stays normally
open and is turned on (closed) by the control chip 23 by means of
a stepped control signal (waveform B) provided at the pin 22P only
when the mobile phone 100 changes into the busy mode.
In the standby mode of the mobile phone 100, periodical turning
on of the first switch 21 enables the battery cells 12 to supply
just sufficient power via the resistor R and diode D1 to the mobile
phone 100 for operation and excessive power via the resistor R to
the capacitor C1 for storage through capacitor charging. Upon periodical
turning off of the first switch 21, the battery cells 12 are disconnected
and the mobile phone 100 operates via the diode D1 on the power/energy
previously stored in the capacitor C1 through capacitor discharging.
This is a power saving mode of the operation of the battery pack
10.
The power output from the battery cells 12 gradually reduces through
use, resulting in the capacitor C1 requiring a progressively longer
charging time or higher charging frequency to store sufficient power
for subsequently operating the mobile phone 100. The charging condition
of the capacitor C1 is measured by its terminal voltage which is
constantly being monitored by the voltage sensor 25. According to
the output of the voltage sensor 25 (by means of edge and/or level
trigger), the control chip 23 instantaneously adjusts the control
signal provided at the pin 21P by way of pulse-width or pulse-frequency
modulation in order to maintain the voltage of the capacitor C1
at a predetermined level, such as 5.2 V, slightly above the aforesaid
minimum voltage of 4.5 V to 5 V for the mobile phone to operate
in the standby mode. For example, when the voltage of the capacitor
C1 runs below the predetermined level, the pulse width in terms
of duty cycles or the pulse frequency of the control signal at the
pin 21P is increased to increase the average closing time or frequency
of the first switch 21 and hence the average charging time or frequency
of the capacitor C1.
Upon the receipt or making of a call, the mobile phone 100 changes
into the busy mode and starts to draw a relatively much larger operating
current from the battery cells 12. In the situation that the first
switch 21 is closed, the enlarged operating current initially flows
through the first switch 21 and is immediately picked up by the
resistor R and hence detected by the current sensor 24. In the alternative
situation that the first switch 21 is open, the enlarged operating
current is initially drawn from the capacitor C1, causing the voltage
of the capacitor C1 to drop rapidly which is immediately detected
by the voltage sensor 25. In either situation, in response to the
edge and/or level trigger by the sensor 24/25, the control chip
23 turns on the second switch 22 to connect the battery cells 12
directly to the mobile phone 100 for the proper supply of the enlarged
operating current. The power saving mode of the operation of the
battery pack 10 is therefore suspended.
At this time, the presence of the diode D1, that being a uni-directional
element, effectively disconnects the capacitor C1 and the continual
periodical turning on and off of the first switch 21 will have no
effect.
The mobile phone 100 resumes the standby mode upon termination
of the call, at which time the control chip 23 opens the second
switch 22 to permit the capacitor C1 to be periodically recharged
by the battery cells 12 and discharged to the mobile phone 100 as
a reserve power source auxiliary to the battery cells 12 in the
power saving mode of the battery pack 10.
The operating circuitry 20 further includes a power-up circuit
26; for operation in a power-up mode, which is controlled by means
of an output pin 26P of the control chip 23. The power-up circuit
26 is formed by an NPN transistor TR, a step-up transformer TX,
a diode D2 and a capacitor C2. The transistor TR has a base connected
to the pin 26 and an emitter connected to the ground G. The transformer
TX has a primary winding which is connected across a collector of
the transistor TR and the positive terminal of the battery cells
12 and a secondary winding which is connected across the ground
and an anode of the diode D2. The capacitor C2 is connected across
a cathode of the diode D2 and the other end of the secondary winding
of the transformer TX. The terminal of the capacitor C2 at the cathode
of the diode D2 is connected to the mobile phone 100 at the circuit
node N3.
In the power-up mode, the control chip 23 switches the transistor
TR on and off at a high frequency by means of a square-wave control
signal (waveform C) at its pin 26P, thereby applying the terminal
voltage of the battery cells 12 repeatedly across the primary winding
of the transformer TX, extracting power from the battery cells 12.
A stepped-up voltage is therefore developed across the secondary
winding of the transformer TR, which is being applied via the diode
D2 to the capacitor C2. The capacitor C2 serves to smooth the stepped-up
voltage and supply the mobile phone 100 with a DC voltage which
is relatively higher than that originally supplied by the battery
cells 12.
The power pack 10 includes an LCD or LED display 30 and two press-switches
31 and 32 provided on the body 11. The display 30 is controlled
by the control chip 23 to indicate, inter alia, the power saving
mode or the power-up mode and to monitor and display, preferably
in the form of a bar/linear display, the terminal voltage/power
level of the battery cells 12. The first press-switch 31 is used
to select various operating modes of the power pack 10, including
the said power saving and power-up modes, a quick charge mode and
a discharge mode. The second press-switch 32 is used to alter the
settings of a selected operating mode.
In areas where the telephone signal is weak and/or when the battery
pack 10 is in a low power condition, it may be advisable to turn
off the power saving mode such that the battery cells 12 are always
in electrical connection to the mobile phone 100. When the power
saving mode is turned off, the control chip 23 opens the first switch
21 and closes the second switch 22 continuously. In the situation
where the telephone signal is very weak and/or the battery pack
10 is in a very lower power condition, the power-up mode may be
turned on for an urgent telephone call to be made or answered.
The control chip 23 may be programmed to have the power saving
mode at different said predetermined levels for operating the mobile
phone 100 in the standby mode, such as 5.2 V, 5.4 V and so on which
are user selectable by means of the press-switch 31 and/or 32 according
to the telephone signal strength of the specific area that the mobile
phone 100 is in.
It is appreciated that the capacitor C1 may be replaced by a rechargeable
battery cell for storing the said excessive power/energy for use
later in the cycle. Also, the switches 21 and 22 may be provided
by, for example, solid-state switches or mechanical switches such
as relays.
The invention has been given by way of example only, and various
modifications of and/or alterations to the described embodiment
may be made by persons skilled in the art without departing from
the scope of the invention as specified in the appended claims.
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