U.S. patent application number 11/111427 was filed with the patent office on 2006-10-26 for method and system for selective control of charging a power source.
Invention is credited to Brian E. Bucknor, Sameh W. Tawadrous, Thomas E. Voor.
Application Number | 20060238416 11/111427 |
Document ID | / |
Family ID | 37110576 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060238416 |
Kind Code |
A1 |
Voor; Thomas E. ; et
al. |
October 26, 2006 |
METHOD AND SYSTEM FOR SELECTIVE CONTROL OF CHARGING A POWER
SOURCE
Abstract
The invention concerns a method (200) and system (100) for
selective control of charging a power source (122). The method can
include the steps of charging (212) the power source of an
electronic device (136) in which the electronic device also
includes a global positioning system unit (118) and conducting
(216) a session for the global positioning system unit. The method
can also include the step of--in response to the
session--selectively throttling (218) the flow of current to the
power source of the electronic device to reduce the effect of
thermal variation on the operation of the global positioning system
unit.
Inventors: |
Voor; Thomas E.; (Parkland,
FL) ; Bucknor; Brian E.; (Miramar, FL) ;
Tawadrous; Sameh W.; (Coral Springs, FL) |
Correspondence
Address: |
MOTOROLA, INC;INTELLECTUAL PROPERTY SECTION
LAW DEPT
8000 WEST SUNRISE BLVD
FT LAUDERDAL
FL
33322
US
|
Family ID: |
37110576 |
Appl. No.: |
11/111427 |
Filed: |
April 21, 2005 |
Current U.S.
Class: |
342/357.74 ;
455/343.1; 713/320 |
Current CPC
Class: |
H04B 1/3883
20130101 |
Class at
Publication: |
342/357.06 ;
455/343.1; 713/320 |
International
Class: |
G01S 5/14 20060101
G01S005/14; G06F 1/26 20060101 G06F001/26; H04B 1/16 20060101
H04B001/16 |
Claims
1. A method for selective control of charging a power source,
comprising: charging a power source of an electronic device,
wherein the electronic device also includes a global positioning
system unit; monitoring the temperature of the global positioning
system unit; conducting a session for the global positioning system
unit; and in response, selectively throttling the flow of current
to the power source of the electronic device to reduce the effect
of thermal variation on the operation of the global positioning
system unit.
2. The method according to claim 1, wherein conducting a session
for the global positioning system unit includes conducting an
acquisition session in which the global positioning system unit
acquires and synchronizes with a plurality of global positioning
system satellites.
3. The method according to claim 1, further comprising monitoring
the voltage on the power source or the amount of current flowing
into the electronic device.
4. The method according to claim 1, wherein during a first phase
based on a first predetermined parameter, selectively throttling
the flow of current includes at least substantially preventing the
current from flowing to the power source.
5. The method according to claim 4, wherein selectively throttling
the flow of current further comprises permitting enough of the
current to flow to the global positioning system unit to allow the
global positioning system unit to operate.
6. The method according to claim 4, wherein the first predetermined
parameter is a predetermined amount of time or a predetermined rate
of temperature change.
7. The method according to claim 1, wherein during a second phase
lasting from the end of a first phase to the point at which the
global positioning system unit reaches a predetermined thermal
equilibrium, selectively throttling the flow of current includes
varying the amount of current flowing to the power source to reduce
the rate of temperature change at the global positioning system
unit.
8. The method according to claim 1, wherein during a third phase
lasting from the point at which the global positioning system unit
reaches a predetermined thermal equilibrium to the point at which
the power source reaches a predetermined charging voltage,
selectively throttling the flow of current includes maintaining the
flow of current at a substantially constant value to reduce the
rate of temperature change at the global positioning system
unit.
9. The method according to claim 1, wherein during a fourth phase
lasting from the point at which the power source reaches a
predetermined charging voltage until the charging process is
complete, selectively throttling the flow of current includes:
maintaining the current flow at its conventional level; or
diverting at least a portion of the flow of current to another
component in the electronic device.
10. The method according to claim 1, wherein the electronic device
is a mobile communications unit.
11. A system for selective control of charging a power source,
comprising: a power source; a charging circuit, wherein the
charging circuit is coupled to and enables the charging of the
power source; a global positioning system unit, wherein the global
positioning system unit determines a physical location of the
system; and a processor coupled to the charging circuit and the
global positioning system unit, wherein the processor is programmed
to monitor the temperature of the global positioning system unit
and--in response to the conducting of a session for the global
positioning system unit and during the charging of the power
source--selectively throttle the flow of current to the power
source to reduce the effect of thermal variation on the operation
of the global positioning system unit.
12. The system according to claim 11, wherein the global
positioning system unit determines the physical location of the
system by acquiring and synchronizing with a plurality of global
positioning system satellites.
13. The system according to claim 11, wherein the processor is
further programmed to monitor the voltage on the power source or
the amount of current flowing into the system.
14. The system according to claim 11, wherein during a first phase
based on a predetermined parameter, the processor is further
programmed to signal the charging circuit to selectively throttle
the flow of current by at least substantially preventing the
current from flowing to the power source.
15. The system according to claim 14, wherein the processor is
further programmed to signal the charging circuit to permit enough
of the current to flow to the global positioning system unit to
allow the global positioning system unit to operate.
16. The system according to claim 14, wherein the first
predetermined parameter is a predetermined amount of time or a
predetermined rate of temperature change.
17. The system according to claim 11, wherein during a second phase
lasting from the end of a first phase to the point at which the
global positioning system unit reaches a predetermined thermal
equilibrium, the processor is further programmed to signal the
charging circuit to selectively throttle the flow of current by
varying the amount of current flowing to the power source to reduce
the rate of temperature change at the global positioning system
unit.
18. The system according to claim 11, wherein during a third phase
lasting from the point at which the global positioning system unit
reaches a predetermined thermal equilibrium to the point at which
the power source reaches a predetermined charging voltage, the
processor is further programmed to signal the charging circuit to
selectively throttle the flow of current by maintaining the flow of
current at a substantially constant value to reduce the rate of
temperature change at the global positioning system unit.
19. The system according to claim 11, wherein during a fourth phase
lasting from the point at which the power source reaches a
predetermined charging voltage until the charging process is
complete, the processor is further programmed to signal the
charging circuit to selectively throttle the flow of current by:
maintaining the current flow at its conventional level; or
diverting at least a portion of the flow of current to another
component in the electronic device.
20. The system according to claim 11, wherein the power source,
charging circuit, global positioning system unit and processor are
part of a mobile communications unit.
21. A portable electronic device, comprising: a power source; a
charging circuit, wherein the charging circuit is coupled to and
enables the charging of the power source; a global positioning
system unit, wherein the global positioning system unit determines
a physical location of the device; a user interface section having
a display and an input/output component; and a processor coupled to
the charging circuit, the global positioning system unit and the
user interface section, wherein the processor is programmed to
monitor the temperature of the global positioning system unit
and--in response to the conducting of a session for the global
positioning system unit and during the charging of the power
source--selectively throttle the flow of current to the power
source to reduce the effect of thermal variation on the operation
of the global positioning system unit.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates in general to charging techniques for
electronic devices and more particularly, to selectively
controlling a power source for electronic devices.
[0003] 2. Description of the Related Art
[0004] The use of portable devices, particularly mobile
communications units, has exploded recently. Manufacturers are
constantly adding features to these devices to make them more
desirable to consumers. In addition, government agencies may order
manufacturers to implement certain features in their devices. As an
example, in part because of consumer demand and in part because of
a government mandate, cellular telephone manufacturers have built
Global Positioning System (GPS) receivers in their products. A GPS
receiver can enable a cellular telephone to determine its physical
location, which can be displayed to a user of the device or
forwarded to some other entity, like an emergency operator.
[0005] GPS receivers typically include a reference oscillator
circuit for purposes of synchronization. In particular, when a GPS
receiver attempts to determine its location, the GPS receiver will
establish communications with the appropriate satellites, relying
on the reference oscillator circuit to do so. There is a
possibility that the frequency of the reference oscillator circuit
will drift, which may prolong the time that it takes for the GPS
receiver to determine its location from the satellites. As an
example, if the temperature of the reference oscillator circuit
varies, the frequency of the reference oscillator circuit will
vary, too. To help solve the problem of frequency drift,
temperature-compensated oscillators (TCXO) have been developed,
which can adjust the reference frequency in view of a temperature
variation.
[0006] There are several ways in which the reference oscillator
circuit may be subjected to heat. For example, almost all cellular
telephones include charging circuits, which can be used to
replenish rechargeable batteries. As the cellular telephone is
charged, heat can be introduced into the device, which may cause
frequency drift in the reference oscillator circuit of the GPS
receiver. This variation in temperature even affects the
performance of TCXOs.
SUMMARY OF THE INVENTION
[0007] The present invention concerns a method for selective
control of charging a power source. The method can include the
steps of charging a power source of an electronic device having a
GPS unit and conducting a session for the GPS unit. In response,
the method can also include the step of selectively throttling the
flow of current to the power source of the electronic device to
reduce the effect of thermal variation on the operation of the GPS
unit.
[0008] As an example, the step of conducting a session for the GPS
unit can include conducting an acquisition session in which the GPS
unit acquires and synchronizes with a plurality of GPS satellites.
The method can also include the step of monitoring at least one of
the temperature of the GPS unit, the voltage on the power source
and the amount of current flowing into the electronic device.
[0009] In one arrangement, during a first phase based on a first
predetermined parameter, the selectively throttling the flow of
current step can include at least substantially preventing the
current from flowing to the power source. Also during the first
phase, the selectively throttling the flow of current step can
include permitting enough of the current to flow to the GPS unit to
allow the GPS unit to operate. As an example, the first
predetermined parameter can be at least one of a predetermined
amount of time and a predetermined rate of temperature change.
[0010] In another arrangement, a second phase can last from the end
of a first phase to the point at which the GPS unit reaches a
predetermined thermal equilibrium. During the second phase, the
selectively throttling the flow of current step can include varying
the amount of current flowing to the power source to reduce the
rate of temperature change at the GPS unit.
[0011] A third phase can last from the point at which the GPS unit
reaches a predetermined thermal equilibrium to the point at which
the power source reaches a predetermined charging voltage. During
the third phase, the selectively throttling the flow of current
step can include maintaining the flow of current at a substantially
constant value to reduce the rate of temperature change at the GPS
unit.
[0012] In yet another arrangement, a fourth phase can last from the
point at which the power source reaches a predetermined charging
voltage until the charging process is complete. During the fourth
phase, the selectively throttling the flow of current step can
include at least one of maintaining the current flow at its
conventional level and diverting at least a portion of the flow of
current to another component in the electronic device. As an
example, the electronic device can be a mobile communications
unit.
[0013] The present invention also concerns a system for selective
control of charging a power source. The system can include a power
source, a charging circuit that can be coupled to and can enable
the charging of the power source and a GPS unit. The GPS unit can
determine a physical location of the system. The system can also
include a processor, which can be coupled to the charging circuit
and the GPS unit. The processor can be programmed to--in response
to an initiation of a session for the GPS unit and during the
charging of the power source--selectively throttle the flow of
current to the power source to reduce the effect of thermal
variation on the operation of the GPS unit. The system can also
include suitable software and circuitry for performing the
processes described above.
[0014] The present invention also concerns a portable electronic
device. The device can include a power source, a charging circuit
that can be coupled to and can enable the charging of the power
source and a GPS unit. The GPS unit can determine a physical
location of the device. The device can also include a user
interface section having a display and an input/output component
and can include a processor coupled to the charging circuit, the
GPS unit and the user interface section. The processor can be
programmed to--in response to a session being conducted for the GPS
unit and during the charging of the power source--selectively
throttle the flow of current to the power source to reduce the
effect of thermal variation on the operation of the GPS unit. The
device can also include suitable software and circuitry for
performing the processes described above.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The features of the present invention, which are believed to
be novel, are set forth with particularity in the appended claims.
The invention, together with further objects and advantages
thereof, may best be understood by reference to the following
description, taken in conjunction with the accompanying drawings,
in the several figures of which like reference numerals identify
like elements, and in which:
[0016] FIG. 1 illustrates a system for selective control of
charging of a power source in accordance with an embodiment of the
inventive arrangements;
[0017] FIG. 2 illustrates a method for selective control of
charging a power source in accordance with an embodiment of the
inventive arrangements; and
[0018] FIG. 3 illustrates a current-voltage graph in accordance
with an embodiment of the inventive arrangements.
DETAILED DESCRIPTION OF THE INVENTION
[0019] While the specification concludes with claims defining the
features of the invention that are regarded as novel, it is
believed that the invention will be better understood from a
consideration of the following description in conjunction with the
drawing figures, in which like reference numerals are carried
forward.
[0020] As required, detailed embodiments of the present invention
are disclosed herein; however, it is to be understood that the
disclosed embodiments are merely exemplary of the invention, which
can be embodied in various forms. Therefore, specific structural
and functional details disclosed herein are not to be interpreted
as limiting, but merely as a basis for the claims and as a
representative basis for teaching one skilled in the art to
variously employ the present invention in virtually any
appropriately detailed structure. Further, the terms and phrases
used herein are not intended to be limiting but rather to provide
an understandable description of the invention.
[0021] The terms a or an, as used herein, are defined as one or
more than one. The term plurality, as used herein, is defined as
two or more than two. The term another, as used herein, is defined
as at least a second or more. The terms including and/or having, as
used herein, are defined as comprising (i.e., open language). The
term coupled, as used herein, is defined as connected, although not
necessarily directly, and not necessarily mechanically. The terms
program, software application, and the like as used herein, are
defined as a sequence of instructions designed for execution on a
computer system. A program, computer program, or software
application may include a subroutine, a function, a procedure, an
object method, an object implementation, an executable application,
an applet, a servlet, a source code, an object code, a shared
library/dynamic load library and/or other sequence of instructions
designed for execution on a computer system.
[0022] The invention concerns a method and system for selective
control of charging a power source. The method can include the
steps of charging a power source of an electronic device in which
the electronic device also includes a GPS unit and conducting a
session for the GPS unit. The method can also include the step
of--in response to the session--selectively throttling the flow of
current to the power source of the electronic device. This process
can reduce the effect of thermal variation on the operation of the
GPS unit. Several examples of how the flow of current can be
selectively throttled will be presented below.
[0023] Referring to FIG. 1, a system 100 for selective control of
charging of a power source is shown. The system 100 can include a
processor 110, a transceiver 112, an antenna 114 (which can be
coupled to the transceiver 112), a user interface section 116, a
GPS unit 118, a charging circuit 120 and a power source 122. The
processor 110 can be communicatively coupled to the transceiver
112, the user interface section 116, the GPS unit 118, the charging
circuit 120 and the power source 122. Also, the processor 110 can
control the operation of one of more of these components. In one
arrangement, the user interface section 116 can include a display
128, an input/output component 130, a speaker 132 and a microphone
134. In another arrangement, the GPS unit 118 can include a sensor
124 and a reference oscillator 126.
[0024] The system 100 can be implemented in an electronic device
136, such as a mobile communications unit. Suitable examples
include cellular telephones, two-way radios, personal digital
assistants, paging devices, etc. Of course, the invention is not
limited to any of these examples, as the electronic device 136 can
be any device having a unit that can determine the physical
location of the device 136.
[0025] The transceiver 112, along with the antenna 114, can
transmit and receive wireless signals in accordance with well-known
principles. In addition, the display 128 of the user interface
section 116 can display images to a user of the electronic device
136 and can also receive input from the user. The speaker 132 can
broadcast audio, and the microphone 134 can capture audio. Further,
the input/output component 130 can be any unit capable of receiving
input from or outputting output to a user of the electronic device
136. Suitable examples include a keypad or any wireless or wired
interface capable of receiving and outputting signals.
[0026] The GPS unit 118, as is known in the art, can acquire
signals from any number of GPS satellites (not shown) and can
synchronize with these satellites. As is also known in the art, the
reference oscillator 126 can assist in this acquisition and
synchronization process or session. In one arrangement, the sensor
124 can be a temperature sensor that can measure the temperature of
or around the GPS unit 118. It is understood that the term global
positioning system unit can include any component that is capable
of determining the location of the electronic device 136 and is not
necessarily limited to one that relies on a satellite-based
system.
[0027] The charging circuit 120 can receive charging current from,
for example, an external power source (not shown) and can transfer
this current to any suitable component of the electronic device
136. As an example, the charging circuit 120--through the receipt
of signals from the processor 110--can control the flow of current
to the power source 122 and the GPS unit 118. The charging circuit
120 may also be coupled to, for example, the user interface section
116. As will be described below, the charging circuit 120 may also
divert charging current to one or more components of the user
interface section 116. The power source 122 can supply power to any
suitable components of the system 100. As an example but without
limitation, the power source 122 can be one or more rechargeable
batteries.
[0028] Referring to FIG. 2, a method 200 for selective control of
charging a power source is shown. To describe the method 200,
reference will be made to FIG. 1, although it is understood that
the method 200 can be implemented in any other suitable device or
system using other suitable components. Moreover, the invention is
not limited to the order in which the steps are listed in the
method 200. In addition, the method 200 can contain a greater or a
fewer number of steps than those shown in FIG. 2.
[0029] At step 210, the method 200 can begin. At step 212, a power
source of an electronic device having a GPS unit can be charged. At
step 214, at least one of the temperature of the GPS unit, the
voltage on a power source and the amount of current flowing into
the electronic device can be monitored. A session can be conducted
for the GPS unit, such as by conducting an acquisition session in
which the GPS unit acquires and synchronizes with a plurality of
GPS satellites, as shown at step 216.
[0030] Referring to FIG. 1, the power source 122 of the electronic
device 136 can be charged. That is, charging current from an
external power supply can pass to the charging circuit 120, which
can direct the current to the power source 122. Also, the processor
110, through the charging circuit 120, can monitor the amount of
current flowing into the electronic device 136 and can also monitor
the voltage on the power source 122. The temperature sensor 124 can
measure the temperature of the GPS unit 118, and these readings can
be transmitted to the processor 110. Through these measurements,
the processor 110 can track temperature variations at the GPS unit
118.
[0031] When it is necessary to obtain positional information, the
processor 110 can signal the GPS unit 118 to do so. There are many
reasons why it may be necessary to determine the location of the
electronic device 136. For example, a user, through the
input/output component 130, may dial an emergency number, such as
911, or may request directions to an address. As is known in the
art, when so requested, the GPS unit 118 may acquire and
synchronize with a plurality of GPS satellites or some other system
that can enable the GPS unit 118 to determine the location of the
electronic device 136. Referring back to the method 200 of FIG. 2,
although the step 216 of conducting the acquisition session is
shown as being after the step 212 of charging the power source, it
is understood that the invention is not so limited; the acquisition
session can be initiated before, after or simultaneous with a
charging process.
[0032] It is understood that the phrase "conducting a session" can
include any process that enables a GPS unit to determine the
physical location of an electronic device. In particular, this
phrase can cover repeatedly executing suitable steps to obtain the
physical location, such as repeating acquisition and
synchronization steps, and the constant tracking of an external
source that the GPS unit acquires and to which it synchronizes.
[0033] At step 218, the flow of current to the power source of the
electronic device can be selectively throttled to reduce the effect
of thermal variation on the operation of the GPS unit. There are
several examples of this process, each of which will be presented
below. For example, at step 220, during a first phase based on a
first predetermined parameter, the current can be substantially
prevented from flowing to the power source. Additionally, enough of
the current can be permitted to flow to the GPS unit to permit the
GPS unit to operate.
[0034] As another example, during a second phase lasting from the
end of the first phase to the point at which the GPS unit reaches a
thermal equilibrium, the amount of current flowing to the power
source can be varied, as shown at step 222. This process can reduce
the rate of temperature change at the GPS unit. In yet another
example, at step 224, during a third phase, lasting from the point
at which the GPS unit reaches a predetermined thermal equilibrium
to the point at which the power source reaches a predetermined
charging voltage, the flow of current to the power source can be
maintained at a substantially constant value. This process can also
reduce the rate of temperature change at the GPS unit. At step 226
and in yet another example, during a fourth phase lasting from a
point at which the power source reaches a predetermined charging
voltage until the charging process is complete, the current flow
can be maintained at its conventional level. Alternatively, at
least a portion of the flow of current can be diverted to another
component in the electronic device. At step 228, the method 200 can
end.
[0035] Referring to FIG. 3, an example of a current-voltage graph
300 that represents a typical charging process for the power source
122, e.g., a rechargeable battery, is shown. Referring to FIGS. 1
and 3, the graph 300 has a voltage curve V that represents the
voltage of the power source 122 over time t. The graph 300 also
includes a current curve I that signifies the amount of current
flowing to the power source 122 over time t. The voltage curve V
has a predetermined charging voltage V.sub.T, which can represent a
maximum charging voltage of the power source 122. The current curve
can have a cutoff threshold I.sub.CT, which is the point at which
the charging of the power source 122 can stop. The graph 300 can
also have four phases, each of which are designated by a Roman
numeral. These phases I-IV can reflect various stages at which
selective control of the charging of the power source 122 may
occur.
[0036] In the first phase (phase I), the current curve I can be at
a maximum charging current value, and the voltage curve V can
increase. The rate of temperature change can be relatively high in
this phase, too, as this first phase typically occurs when the
process of charging the power source 122 begins. If a session is
conducted for the GPS unit 118 during the first phase, then the
processor 110 can signal the charging circuit 120 to substantially
prevent the current from flowing to the power source 122. As an
option, the processor 110 can also signal the charging circuit 120
to permit enough current to flow to the GPS unit 118 to allow the
GPS unit 118 to operate.
[0037] For example, the maximum charging current value, the amount
of charging current entering the electronic device 136, may be 850
milli-amps (mA). Almost all of this current may be directed to the
power source 122. When the session for the GPS unit 118 is
detected, the charging circuit 120 can reduce the amount of current
being transferred to the power source 122 to substantially zero
(substantially zero can include true zero or slight or even
moderate deviations from zero). By cutting off the flow of current
to the power source 122, the likelihood that a temperature
variation will affect the operation of the GPS unit 118 can be
reduced. Once the session for the GPS unit 118 is complete, the
processor 110 can signal the charging circuit 120 to resume the
normal course of charging. In this case, the charging current being
directed to the power source 122 can return to its maximum charging
value, or roughly 850 mA.
[0038] It should be noted that suitable amounts of current may be
permitted to flow to the power source 122 in this first phase, if
so desired. For example, if the GPS unit 118 is constantly tracking
the external source that it has acquired and to which it is
synchronized, a suitable amount of current can be permitted to
reach the power source 122. This scenario is possible because the
constant tracking of the external source can allow for a greater
frequency drift and, hence, a greater temperature variation at the
GPS unit 118. The amount of current permitted to pass to the power
source 122 in this example can still fall within the definition of
substantially prevent, as described above.
[0039] If the flow of current to the power source 122 is
substantially prevented as described above, it may be desirable to
divert some of this charging current to the GPS unit 118. In
particular, the GPS unit 118 normally receives power from the power
source 118. It the power source 118 has been depleted and charging
current is being prevented from flowing to the power source 122,
the charging circuit 120 may allow some of the charging current to
reach the GPS unit 118. This amount of current can be enough to
enable the GPS unit 118 to complete its task of acquiring
positional information for the electronic device 136.
[0040] As noted earlier, the first phase can be based on a
predetermined parameter. Specifically, the duration of the first
phase can be based on a predetermined amount of time or on a
predetermined rate of temperature change. For example, after a
predetermined amount of time, the processor 110 can instruct the
charging circuit 120 to control the flow of charging current in
accordance with a manner that is suitable for the second phase
(phase II), which will be described below.
[0041] Alternatively, the processor 110 can monitor the temperature
variations present at the GPS unit 118. As an example, the
processor 110 can monitor the rise in temperature that may occur at
the GPS unit 118 during the charging process. If the rate of
temperature change remains above a predetermined threshold, the
processor 110 can determine that the flow of current to the power
source 122 can be controlled in accordance with the procedures
associated with the first phase. It is understood, however, that
the invention is not limited to these examples, as any other
suitable parameter can be used to determine the duration of the
first phase.
[0042] In the second phase, the current curve I can be at a maximum
charging current value, and the voltage curve V can continue to
increase. Here, the rate of temperature change may not be as great
as in the first phase. As such, the processor 110 can signal the
charging circuit 120 to vary the amount of charging current flowing
to the power source 122 to reduce the effect of thermal variation
at the GPS unit 118, if a session for the GPS unit 118 is
conducted.
[0043] For example, if the processor 110 detects, through the
temperature sensor 124, that the rate of temperature change at the
GPS unit 118 may affect the operation of the GPS unit 118, the
processor 110 can signal the charging circuit 120 to reduce the
amount of current flowing to the power source 122. The drop in
current can cause a corresponding decrease in the rate of
temperature change. If necessary, the processor 110 may also signal
the charging circuit 120 to return the magnitude of the current to
its previous level or some other suitable value. In either
arrangement, the key is to minimize the amount of temperature
variation at the GPS unit 118 when a session for the GPS unit 118
is conducted. Once the session is complete, the processor 110 can
signal the charging circuit 120. In response, the charging circuit
120 can permit the level of charging current being transferred to
the power source 122 to return to its pre-session magnitude, if
necessary.
[0044] The duration of the second phase can last from the end of
the first phase to the point at which the GPS unit 118 reaches a
predetermined thermal equilibrium. The processor 110 can determine
when the GPS unit 118 reaches the thermal equilibrium. Any suitable
range of temperature can serve as the predetermined thermal
equilibrium.
[0045] In the third phase (phase III), similar to the second phase,
the current curve I can remain at a maximum charging current value,
and the voltage curve V can continue to increase. Here, however,
the GPS unit 118 can be at a thermal equilibrium. As such, if a
session is conducted for the GPS unit 118, the processor 110 may
signal the charging circuit 120 to maintain the flow of current to
the power source 122 at a substantially constant value during the
third phase. By doing so, the rate of temperature change can also
be kept substantially constant, which can reduce the thermal
effects on the operation of the GPS unit 118. Of course, once the
session for the GPS unit 118 is over, the charging current to the
power source 122 can remain unchanged.
[0046] In one embodiment, the third phase can last from the point
at which the GPS unit 118 reaches a thermal equilibrium to the
point at which the power source 122 reaches a predetermined
charging voltage VT. In one arrangement, the predetermined charging
voltage V.sub.T can be the maximum charging voltage of the power
source 122, although other suitable values are within contemplation
of the inventive arrangements.
[0047] In the fourth phase (phase IV), the voltage curve V can
reach the predetermined charging voltage V.sub.T and can remain at
that level until the charging process is complete. The current
curve I can gradually decrease, as the level of current required to
maintain the power source 122 at the predetermined charging voltage
V.sub.T decreases. During the fourth phase, if the processor 110
detects that a session is being conducted for the GPS unit 118, the
processor 110 can signal the charging circuit 120 to perform one of
two actions: (1) to maintain the current flow to the power source
122 at its conventional level; or (2) divert at least a portion of
the flow of current to another component in the electronic device
136.
[0048] In particular, as the current curve I gradually decreases,
the rate of change in the temperature of the GPS unit 118 may be
relatively small. In fact, it may be small enough to have a
negligible effect on the operation of the GPS unit 118 during a
session. As such, the charging circuit 120 can keep the charging
current level at the magnitude that it would normally follow if no
session for the GPS unit 118 were conducted.
[0049] Alternatively, the processor 110 may determine that the
change in temperature may affect the operation of the GPS unit 118
beyond an acceptable level. If so, the processor 110 can signal the
charging circuit 120 to divert some current to, for example, one or
more components of the user interface section 116, such as the
display 128. As a result, the current curve I may not decrease as
quickly as it normally would, may level off or may begin to rise.
In any event, the rate of temperature change at the GPS unit 118
can be reduced, which may result in improved performance for the
GPS unit 118.
[0050] Once the session for the GPS unit 118 is complete, the
processor 110 can instruct the charging circuit 120 to return the
level of current to the power source 122 to its pre-session
magnitude. In one arrangement, the fourth phase can last from the
point at which the power source 122 reaches the predetermined
charging voltage V.sub.T until the charging process is complete. As
an example, the charging process can be complete when the current
curve I reaches the cutoff threshold I.sub.CT.
[0051] Although several examples have been presented that
demonstrate how current to a power source can be selectively
throttled during a GPS session, it is important to note that the
invention is not limited to them. In fact, any suitable technique
for selectively throttling current during a GPS session can be
employed, as long as the selected technique has the capability of
reducing thermal effects on the operation of the GPS unit.
[0052] In addition, where applicable, the present invention can be
realized in hardware, software or a combination of hardware and
software. Any kind of computer system or other apparatus adapted
for carrying out the methods described herein are suitable. A
typical combination of hardware and software can be a mobile
communication device with a computer program that, when being
loaded and executed, can control the mobile communication device
such that it carries out the methods described herein. The present
invention can also be embedded in a computer program product, which
comprises all the features enabling the implementation of the
methods described herein and which when loaded in a computer
system, is able to carry out these methods.
[0053] While the preferred embodiments of the invention have been
illustrated and described, it will be clear that the invention is
not so limited. Numerous modifications, changes, variations,
substitutions and equivalents will occur to those skilled in the
art without departing from the spirit and scope of the present
invention as defined by the appended claims.
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