U.S. patent application number 11/234578 was filed with the patent office on 2006-01-26 for reducing power consumption in a networked battery-operated device using sensors.
This patent application is currently assigned to Microsoft Corporation. Invention is credited to Paramvir Bahl, Eugene Shih, Michael Sinclair.
Application Number | 20060019724 11/234578 |
Document ID | / |
Family ID | 28674699 |
Filed Date | 2006-01-26 |
United States Patent
Application |
20060019724 |
Kind Code |
A1 |
Bahl; Paramvir ; et
al. |
January 26, 2006 |
Reducing power consumption in a networked battery-operated device
using sensors
Abstract
A method and system for mobile device power consumption
management decreases the instantaneous power consumption of a
mobile device, increasing operational lifetime of the device. In an
embodiment of the invention, the mobile device is associated with a
plurality of device behavior modification techniques that can be
set in response to data collected from a plurality of sensors
associated with the device. In an embodiment, the sensors detect
the device's motion, tilt, proximity to a user, contact with a
user, and orientation with respect to a user. In a further
embodiment, the sensors detect a temperature related to the device
or its environment.
Inventors: |
Bahl; Paramvir; (Sammamish,
WA) ; Shih; Eugene; (Seattle, WA) ; Sinclair;
Michael; (Kirkland, WA) |
Correspondence
Address: |
Microsoft Corporation;c/o WOLF, GREENFIELD & SACKS, PC
FEDERAL RESERVE PLAZA
600 ATLANTIC AVENUE
BOSTON
MA
02210-2206
US
|
Assignee: |
Microsoft Corporation
Redmond
WA
|
Family ID: |
28674699 |
Appl. No.: |
11/234578 |
Filed: |
September 23, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10124720 |
Apr 17, 2002 |
|
|
|
11234578 |
Sep 23, 2005 |
|
|
|
Current U.S.
Class: |
455/574 ;
455/343.1 |
Current CPC
Class: |
H04W 52/0225 20130101;
G06F 1/3203 20130101; H04M 1/72454 20210101; Y02D 30/70 20200801;
H04W 52/0277 20130101; G06F 1/3231 20130101; Y02D 10/00 20180101;
H04W 52/0251 20130101 |
Class at
Publication: |
455/574 ;
455/343.1 |
International
Class: |
H04B 1/16 20060101
H04B001/16; H04B 1/38 20060101 H04B001/38 |
Claims
1. A method for reducing the power consumption of a mobile wireless
device, comprising: receiving a plurality of sensed values from a
plurality of environmental sensors; mapping the plurality of sensed
values to a setting list for a plurality of power consumption
variables, wherein the setting list comprises an indication of a
state of each of the plurality of power consumption variables; and
setting the power consumption variables according to the setting
list, whereby the average power consumption of the mobile wireless
device is reduced.
2. The method according to claim 1, wherein the mobile wireless
device comprises a screen, a non-visual notification mechanism, and
a wireless network interface; and wherein the plurality of power
consumption variables includes a screen setting, a nonvisual
notification mechanism setting, and a registration frequency
setting, wherein setting the power consumption variables further
comprises: setting the screen setting to one of an on value and an
off value, wherein when the screen setting is set to the on value,
information is presented on the screen, and when the screen setting
is set to the off value, the screen is substantially darkened and
does not present any information thereon; setting the non-visual
notification mechanism by setting an audible notification mechanism
to one of a quiet, soft, and loud mode, and setting an inaudible
notification mechanism to one of a stationary and vibrational mode;
and setting the registration frequency setting to one of a normal
mode and a low frequency mode, wherein the normal mode causes the
device to send registration or presence information from the
wireless network interface at a first frequency, and wherein the
low frequency mode causes the device to send registration or
presence information from the wireless network interface at a
second frequency, wherein the second frequency is lower than the
first frequency.
3. The method according to claim 2, wherein the quiet, soft, and
loud modes of the audible notification mechanism cause the device
to activate a ringer in response to incoming calls, wherein the
ringer volume is zero, a first value, or a second value
respectively, wherein the first value is less than the second
value.
4. The method according to claim 2, wherein the stationary and
vibrational modes of the inaudible notification mechanism cause the
device to either deactivate or activate, respectively, a vibrator
associated with the device in response to incoming calls.
5. The method according to claim 2, wherein the plurality of power
consumption variables further comprises a standby setting, wherein
the standby setting may be set to either a normal or standby mode,
wherein the device uses less power in the standby mode than in the
normal mode.
6. A low power wireless device comprising: a screen for displaying
information to a user; a ringer for audibly apprising the user of
an incoming communication; a vibrator for providing the user with a
tactile prompt apprising the user of an incoming communication; a
network interface for interfacing the device to a wireless
transceiver; and a sensor array comprised of a plurality of sensors
for sensing a plurality of qualities of an environment of the
device and for yielding an output related thereto, wherein the
sensor array output is utilized to affect the operation of at least
one of the screen, the ringer, the vibrator, and the network
interface.
7. The device according to claim 6, wherein the wireless
transceiver resides at an access point to a network.
8. The device according to claim 6, wherein the wireless
transceiver resides at another wireless mobile device.
9. The device according to claim 6, wherein when the sensor array
output indicates that a user is not close to the device, the
operation of the ringer and vibrator are affected so that in
response to notification of an incoming communication received at
the wireless interface, the ringer provides an audible signal of a
maximum volume and the vibrator is not activated, and the operation
of the screen is affected so that it does not receive full
power.
10. The device according to claim 6, wherein when the sensor array
output indicates that a user is close to the device, but not
looking at the device screen or having the device in a pocket, the
operation of the ringer and vibrator are affected so that in
response to notification of an incoming communication received at
the wireless interface, the ringer provides an audible signal. of
less than a maximum volume, and the vibrator is not activated, and
the operation of the screen is affected so that it does not receive
power.
11. The device according to claim 6, wherein when the sensor array
output indicates that a user is touching the device or has the
device in a pocket, but is not looking at the device screen, the
operation of the ringer and vibrator are affected so that in
response to notification of an incoming communication received at
the wireless interface, the ringer provides no audible signal, and
the vibrator is activated, and the operation of the screen is
affected so that it does not receive power.
12. The device according to claim 6, wherein the device supports a
normal mode of operation and a standby mode of operation, and
wherein the device consumes less power in the standby mode than in
the normal mode, whereby when the sensor array output indicates
that a user is not close to the device, the device is placed in the
standby mode.
13. A method for modifying the operation of a battery-powered
mobile device to extend the operational lifetime of the device
battery, comprising: detecting the status of a plurality of device
environmental variables; associating the status of the plurality of
device environmental variables with a device behavior pattern; and
modifying the operation of the device so that such operation is
consistent with the device behavior pattern.
14. The method according to claim 13, wherein detecting the status
of a plurality of device environmental variables further comprises
receiving a sensor output from at least two of a proximity sensor,
a ranging sensor, and an accelerometer.
15. The method according to claim 14, wherein detecting the status
of a plurality of device environmental variables further comprises
receiving a sensor output from at least one of a touch sensor, a
temperature sensor, and a tilt sensor.
16. A method for reducing power consumption of a wireless device,
comprising: sensing a plurality of environmental values from a
plurality of environmental sensors; associating the plurality of
sensed environmental values with a desired state of a plurality of
power consumption variables; and regulating a state of the
plurality of power consumption variables according to the desired
state of the plurality of power consumption variables, whereby the
average power consumption of the mobile wireless device is
reduced.
17. The method according to claim 16, wherein associating the
plurality of sensed environmental values with a desired state of a
plurality of power consumption variables comprises using at least
two of the plurality of sensed environmental values as input to at
least one relational formula, whereby the at least one formula
yields a desired state of at least one of the plurality of power
consumption variables.
18. The method according to claim 16, wherein associating the
plurality of sensed environmental values with a desired state of a
plurality of power consumption variables comprises using at least
two of the plurality of sensed environmental values to search a
table, whereby a table entry associated with the at least two of
the plurality of sensed environmental values yields a desired state
of at least one of the plurality of power consumption variables.
Description
RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 10/124,720, filed Apr. 17, 2002, entitled
REDUCING POWER CONSUMPTION IN A NETWORKED BATTERY-OPERATED DEVICE
USING SENSORS, now pending.
TECHNICAL FIELD OF THE INVENTION
[0002] The present invention relates generally to mobile computing
devices, and more particularly, to power consumption reduction in a
mobile computing device using sensors.
BACKGROUND OF THE INVENTION
[0003] With the advent of extreme miniaturization in electronic
components, many new types of devices and activities have become
possible and even prevalent. For example, the use of many types of
mobile devices that use radio frequency signals for connectivity
has become routine. One such device is a cell phone, and another is
a personal information device, i.e. a handheld computing device
that is usable for tasks such as scheduling appointments as well as
tasks such as communicating over a network with another user having
a similar or other device.
[0004] While mobile computing devices such as those mentioned
above, as well as others, confer many benefits on their users,
there are certain limitations imposed by such devices that are not
experienced with non-mobile devices. For example, one dominant
problem associated with mobile devices is the problem of
operational lifetime between battery charges. As the user uses a
device, the device power source, typically a battery, becomes
depleted, eventually falling below a level required for operation
of the device. At such time, the user must recharge or rejuvenate
the power supply before continuing to use the device. This
requirement for battery renewal can be problematic for several
reasons. First, if the battery becomes depleted unexpectedly, the
user may be greatly inconvenienced if he or she was relying on the
device for some functionality, such as emergency calling etc.
Additionally, even if the user is aware of the depletion and
responds by beginning to charge the battery, the device will
generally not be mobile and usable until after the charge cycle is
complete, decreasing the overall general usefulness of the
device.
[0005] Today's mobile devices often recognize the limited capacity
of battery power sources by incorporating certain power-saving
features. Such features include activating a screen or other user
interface element only when the device is actively used by a user.
For example, a cell phone may always be ready to receive an
incoming call, but the device display screen may remain dark or
blank until a user receives a call. Some personal information
devices also incorporate features to activate the device only when
it is being held and used. Furthermore, many mobile devices
incorporate a power switch so that the device may be entirely
powered down for a desired period. For example, a cell phone user
may turn the phone completely off when no calls are expected to be
made or received. However, such measures do not take full advantage
of environmental cues to reduce power consumption.
[0006] In addition, while battery technologies have advanced
rapidly in past years, the current rate of battery technology
development is not keeping pace with the increasing capabilities
and power drain of mobile devices. Thus, although techniques such
as those mentioned above have been useful in somewhat increasing
mobile device battery life, device operational lifetimes continue
to be fairly limited, and better mobile device power management
techniques are required to further reduce battery consumption and
increase device operational lifetimes.
SUMMARY OF THE INVENTION
[0007] To address the deficiencies in existing mobile device power
systems and techniques, an improved system and method of mobile
device power consumption minimization are disclosed. In an
embodiment of the invention, a mobile device supports a plurality
of behavior modification techniques that can cooperate to
collectively reduce the instantaneous power consumption of the
device. Sensors located at, on, or within the device are used to
establish a set of context conditions for the device, which context
conditions are then used to selectively establish the state of each
of the plurality of behavior modification techniques. In a further
embodiment, the sensors detect and yield an output relating to the
device's motion, tilt, proximity to a user, contact with a user,
and orientation with respect to a user. In a further embodiment,
the sensors detect the temperature of an ambient mass such as
ambient air, or the temperature of a contacting body such as a hand
or table.
[0008] Additional features and advantages of the invention will be
made apparent from the following detailed description of
illustrative embodiments that proceeds with reference to the
accompanying figures.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] While the appended claims set forth the features of the
present invention with particularity, the invention and its
advantages may be best understood from the following detailed
description taken in conjunction with the accompanying drawings, of
which:
[0010] FIG. 1 is a schematic diagram of an exemplary computer
network environment including a mobile computing device, within
which embodiments of the invention may be implemented;
[0011] FIG. 2 is a schematic diagram illustrating the architecture
of an exemplary mobile computing device according to an embodiment
of the invention;
[0012] FIG. 3A is a table illustrating a configuration of sensor
outputs usable in an embodiment of the invention to determine
whether a mobile computing device is moving;
[0013] FIG. 3B is a table illustrating a configuration of sensor
outputs usable in an embodiment of the invention to determine
whether a mobile computing device is in a pocket;
[0014] FIG. 3C is a table illustrating a configuration of sensor
outputs usable in an embodiment of the invention to determine
whether a mobile computing device is being looked at by a user;
[0015] FIG. 3D is a table illustrating a configuration of sensor
outputs usable in an embodiment of the invention to determine
whether a mobile computing device is close to a user;
[0016] FIG. 4 is a flow chart illustrating a process for applying
context information to affect the behavior of a mobile computing
device according to an embodiment of the invention;
DETAILED DESCRIPTION OF THE INVENTION
[0017] The invention relates to a method and system for reducing
power consumption in a mobile device through the use of sensors. In
particular, an array of sensors are provided on a device, and their
combined outputs are used to affect the power consumption of the
device. In this manner, much longer device operational lifetimes
may be achieved without a decrease in device usability.
[0018] Referring to FIG. 1, a basic network topology is shown
within which a mobile device may be used according to an embodiment
of the invention. Typically, a mobile device 101 is transiently
connected to a closest access point 103 of a plurality of access
points 103, 105, 107. The access points 103, 105, 107 serve to
interface the mobile device 101 to an infrastructure 109 such as a
network. The access points may be for example wireless network
access points such as according to the IEEE 802.11 standard for
mobile computers and other devices, or cell phone cell transceivers
where the mobile device 101 is a cell phone. The reason for
providing a number of access points is that the range of the
wireless medium, typically a radio frequency communication channel,
is spatially limited, while the user is spatially unconstrained and
may move about, hence moving into or out of range with respect to a
particular access point. The underlying infrastructure 109 is
typically predominantly not mobile, and may be a telephone
infrastructure such as is typically interfaced to a cell
transceiver, or other network such as a corporate LAN or the
Internet interfaced to a wireless access point.
[0019] When a mobile device 101 communicates information to an
access point 103, the purpose is generally to communicate with
another device 111, mobile or otherwise, also interfaced to, or
part of, the infrastructure 109. The other device 111 may be
another similar device such as a computer, cell phone, or hand held
information device used by another user, or may be a different type
of device such as a server. The latter case includes but is not
limited to the situation where a mobile device registers with a
server within the infrastructure 109.
[0020] Generally, the mobile device 101 initially establishes a
connection with the closest access point 103, and periodically
thereafter informs the access point 103 of its continued presence
while the device 101 remains within radio range. As the device 101
is moved out of radio range of one access point 103 and into radio
range of another access point 105, the connection process may be
repeated with respect to the new access point 105, while the
connection to the old access point 103 times out or is explicitly
ended. When the device 101 is out of radio range of any access
point 103, 105, 107, the device 101 is no longer able to interface
with the infrastructure 109. In such a case it will still typically
be usable for functions that do not require any information beyond
what is stored on the device itself. For example, if the device 101
is a mobile computer or personal information device, it will still
be usable for any functions that do not require communication to
the infrastructure 109.
[0021] Referring to FIG. 2, an example of a basic configuration for
a computing device, such as device 101, on which the system
described herein may be implemented is shown. In its most basic
configuration, the computing device 220 typically includes at least
one processing unit 242 and memory 244 although such is not
required. Depending on the exact configuration and type of the
computing device 220, the memory 244 may be volatile (such as RAM),
non-volatile (such as ROM or flash memory) or some combination of
the two. This most basic general configuration is illustrated in
FIG. 2 by dashed line 246. Additionally, the computing device may
also have other features/functionality. For example, device 220 may
also include additional removable data storage components 221
and/or non-removable data storage components 223 including, but not
limited to, magnetic or optical disks or tape. Computer storage
media includes volatile and non-volatile, removable and
non-removable media implemented in any method or technology for
storage of information such as computer-readable instructions, data
structures, program modules, or other data. Computer storage media
includes, but is not limited to, RAM, ROM, EEPROM, flash memory or
other memory technology, CD-ROM, digital versatile disk (DVD) or
other optical storage, magnetic cassettes, magnetic tape, magnetic
disk storage or other magnetic storage devices, or any other medium
which can be used to store the desired information and which can be
accessed by the computing device 220. Any such computer storage
media may be part of the computing device 220.
[0022] The computing device 220 also preferably contains
communication connections 248 that allow the device to communicate
with other devices. Such communications connections preferably
include an interface, such as a network interface card (NIC) to a
wireless device such as another device similar to device 220 or a
wireless access point to a network or infrastructure. A
communication connection is an example of a communication medium.
Communication media typically embodies readable instructions, data
structures, program modules or other data in a modulated data
signal such as a carrier wave or other transport mechanism and
includes any information delivery media. By way of example, and not
limitation, communication media includes wired media such as a
wired network or direct-wired connection, and wireless media such
as acoustic, RF, infrared and other wireless media. The term
computer readable media as used herein includes both storage media
and communication media.
[0023] A computing device 220 may also have input devices 247 such
as a keyboard, mouse, pen, voice input device, touch input device,
etc. Preferably output devices such as a ringer 249 and/or vibrator
251 are also included when appropriate, such as for a cell phone or
paging device. Furthermore, for wireless mobile devices, the
computing device 220 is preferably provided with a portable power
source 250, such as a battery pack, fuel cell or other power
module. The power source 250 acts as a primary source of power for
computations and wireless data transmissions to be performed by the
device. The device may support a standby mode of operation wherein
the device 220 consumes less power than in an ordinary mode of
operation, perhaps at the expense of increased response time with
respect to incoming communications, decreased bandwidth, and/or
decreased radio range.
[0024] Device 220 also embodies a sensor array 252 including a
plurality of sensors to detect and convey the context of the device
220 for power reduction as described more fully hereinafter.
Exemplary sensors include a temperature sensor 253, a proximity
sensor 255, one or more accelerometers 257, a tilt sensor 259, a
touch sensor 261, and an IR ranging sensor 263 such as using an IR
LED. Each sensor yields an output indicative of the sensed quantity
or quality. Exemplary sensor details will be discussed below,
although the invention is not limited to the sensors shown or the
features described with respect to each sensor.
[0025] The temperature sensor 253 is preferably disposed so as to
measure the temperature of the device 220 at a location on the
surface of the device 220. Ideally, the temperature sensor 253 is
mounted so that it will contact a user's hand when the device 220
is held in a typical location for use. In this manner, the
temperature sensor 253 will indicate a different temperature when
the device 220 is held by a user than when the device is not held,
such as when it is on a table, etc. The temperature sensor 253 also
preferably reacts to the ambient environmental temperature through
convection and/or radiative heating effects when heating via a
user's touch is not predominant. Any of the commercially available
temperature sensors may be utilized for the temperature sensor
253.
[0026] The proximity sensor 255 is preferably a capacitive device
that detects the proximity of a user within a fairly close range
such as less than 0.5 meters. In an embodiment of the invention,
the proximity sensor 255 is a single-plate capacitive device that
detects a change in capacitance with respect to the plate caused by
the nearness of a body such as a user. In an alternative
embodiment, the proximity sensor 255 is a two-plate capacitive
device, which is typically capable of detecting a body at a greater
distance than a similar single-plate device. Generally, capacitive
sensors detect change in capacitance by observing the decay
characteristics of a circuit that includes the capacitive element,
such as a plate, and any parasitic capacitance such as caused by a
nearby individual. In particular, in one mechanism, the capacitive
plate is pulsed by an output pin which pin is then used as an input
to observe the plate voltage decay rate. Higher capacitance will
generally lead to a detectably slower voltage decay rate.
[0027] The accelerometers 257 preferably comprise a grouping of
linear accelerometers for detecting movement of the device 220 in
any direction. Typically, this will require the use of three
accelerometers, one for each axis of potential movement.
Alternatively, the accelerometer group 257 may comprise a triaxial
accelerometer, or one or more biaxial accelerometers. The
accelerometers 257 may be of any type, including mass/spring, such
as the ADXL50 produced by ANALOG DEVICES, or the ADXL105, ADXL202,
and ADXL210 also produced by ANALOG DEVICES, or any other type. The
accelerometers 257 yield an indication of when and to what degree
the device accelerates along any axis. Alternatively, the
accelerometers 257 may yield an indication of acceleration only
along one or two axes.
[0028] The tilt sensor 259 comprises any device capable of sensing
a tilting of the device 220 either via tilt angle measurement or
angular acceleration measurement, or otherwise. The tilt sensor 259
yields an output indicative of the amount of tilt experienced by
the device 220, or yields an output from which can be derived the
same information. The tilt sensor preferably detects an absolute
amount of tilt from a horizontal position in one or more axes of
the device 220, but may alternatively detect a relative amount of
tilt, referenced only to a prior position. Note that an
accelerometer may be used as a component of the tilt sensor in one
embodiment. This is especially true of accelerometers that can
measure static acceleration such as the aforementioned devices
produced by ANALOG DEVICES. A mass/spring accelerometer detects
displacement of a mass, which can occur due to either dynamic
acceleration, such as caused by a sudden displacement, or static
acceleration, such as caused by gravity when the mass translation
axis is tilted from horizontal.
[0029] The touch sensor 261 provides similar information to that
provided by the proximity sensor but is much more limited in range.
Thus, the touch sensor 261 detects and yields an output indicative
of a condition wherein a user's hand or other part of their body is
either in contact with the device 220 or is substantially in
contact with the device 220, such as through a glove. The touch
sensor is preferably a capacitive device such as those described
above with respect to the proximity sensor 255, adapted to provide
the required short range. Alternatively, the touch sensor comprises
a pressure sensitive element that senses direct contact without
necessarily sensing other degrees of proximity. Such pressure
sensitive element may be either a micro switch, or a solid state
device such as a strain gauge, or otherwise, without limitation.
The touch sensor 261 can also be distributed in two or more
noncontiguous regions on the device 220. For example, the touch
sensor 261 may comprise two or more separate elements operating on
the same or different principles of operation.
[0030] Finally, the IR ranging sensor 263 is disposed so as to
detect the presence in front of the device 220 of a body such as an
operator. Preferably the IR ranging sensor 263 comprises an IR
light emitting diode (LED), operable to send from the front of the
device 220 a coded beam of IR radiation, the reflection of which
can be detected and processed to determine the presence and
approximate distance in front of the device 220 of an operator or
other body. In particular, the IR ranging sensor 263 preferably
transmits a beam of IR radiation having a known data content.
Subsequently, an IR detector associated with the IR ranging sensor
263 detects any return reflection of the transmitted beam. The data
content of the return reflection, if any, is compared to the known
data content of the transmitted beam, and a measure of the errors
between the two is generated. The degree of error is then used to
give an approximate range estimation of the distance between the
device 220 and the reflecting body. For example, at very close
ranges, such as 6 cm or less, the error rate between the
transmitted and reflected beam may be almost zero, whereas at
greater distances such as 60 cm, the error rate may exceed 50%. One
alternative technique is to alter the duty cycle of a transmitted
pulse train, and detect the threshold duty cycle at which a
detectable reflection occurs, from which information an approximate
range to the reflecting body may be derived.
[0031] While the aforementioned techniques can be used to
approximate a range, it will be understood that these techniques
are not exact and may, for example, be significantly affected by
the color and reflectance of the detected body. If higher accuracy
is required in a specific implementation of the invention, then a
more accurate range detector will preferably be employed. In any
case, a different range detection technique or device may be
utilized without departing from the scope of the invention.
[0032] Note that collection of information from the sensors may be
performed according to any one or more standard techniques. For
example, the sensor outputs maybe periodically polled, the sensors
may trigger an event periodically when output information changes,
or the sensor outputs may be written to a common area of memory to
be gathered at a later time. Those of skill in the art will
appreciate that there are a number of other techniques that may be
used additionally or alternatively to gather sensor output
information, and the foregoing list is therefore exemplary rather
than exhaustive.
[0033] The use of some or all of the aforementioned sensors or
sensor groups to affect the power consumption of the device 220
will now be described by reference to FIGS. 3a-3d. There are a
number of context variables that the aforementioned sensor array
can detect and report. For example, the sensors can be used to
determine whether a device is moving or not, whether the device is
in the user's pocket or not, whether the device is close to the
user or not, and whether the device is being looked at or not. The
power consumption variables that can be controlled based on these
context variables include at least the device's screen power, ring
power, vibrator power, and radio power used during registration
updating. If the device 220 supports a low power standby mode of
operation, entry into and exit from this mode may also be
controlled according to the context variable values.
[0034] Each of FIGS. 3a-3d describes a set of context variable
values that leads to one or more conclusions regarding device
context and hence regarding device power savings steps to be taken.
Note that the context conditions described with respect to the
figures are not necessarily mutually exclusive. For example, a
person may be walking with the device 220 and may also have the
device 220 in his or her pocket. FIG. 3a shows the likely context
variable values read when the device 220 is being moved, or
transported, by the user walking. In this case, most of the sensor
readings will be indeterminate, and hence not useful in determining
whether the user is walking with the device 220 or not. These
variables are marked with "NA" in the figure.
[0035] However, the accelerometers 257 will likely show a highly
variable output when the user is walking with the device 220. In
addition, depending upon the technology used to implement the tilt
sensor 259, this sensor may also show increased activity with high
variability while the user is walking with the device 220. The
reaction of the accelerometers 257 and potentially the tilt sensor
259 is due to the fact that the motion used in walking subjects the
device 220 to semi-periodic shock acceleration loads, such as when
a foot strikes the floor, as well as semi-periodic translational
acceleration loads such as when the user swings his hand with the
device 220 in it, or when the user moves forward after a foot fall.
In addition, there are a number of other acceleration loads,
periodic or otherwise, that the device 220 may be subjected to
while the user walks.
[0036] FIG. 3b shows the likely context variable values read when a
user has the device 220 in his or her pocket. As can be seen, many
of the sensor readings will be indeterminate with respect to
whether the user has the device 220 in his or her pocket, and these
variables are thus marked with "NA" in the figure. Three of the
sensors will, however, likely have a distinct reaction when the
user has the device 220 in a pocket. In particular, the proximity
sensor 255 will likely give a reading indicating a close proximity,
since the user will most likely be quite close on the opposite side
of the pocket material. Note that the touch sensor 261, which
reacts only to much closer contact, preferably will not react when
the device 220 is in a pocket, and will thus indicate no touch
occurring. In addition, the IR ranging sensor 263 will experience
great reflectivity due to the closeness of the pocket material, and
will hence likely yield a reading indicative of an adjacent body at
very close range.
[0037] FIG. 3c shows the likely context variable values read when a
user is looking at the screen of the device 220. In particular, the
proximity sensor 255 should yield a reading indicative of high
proximity if the user is close enough to observe the screen of the
device 220. Typically, a user will view a screen from a distance of
approximately 24 cm, corresponding roughly to the relaxed focus
point of the human eye. In addition, for many devices optimized for
hand held operation, the user will naturally tilt the device 220
toward themselves, and thus the tilt sensor 259 for the device 220
will yield an output indicative of a substantial tilt such as 45
degrees from horizontal. As well, for devices optimized for hand
held operation the user will generally be gripping the device 220
during viewing, and hence the touch sensor 261 will typically yield
an output indicating that the device 220 is being touched when the
user is looking at the screen of the device 220. Finally, since the
user will typically look at the screen of the device 220 from a
position in front of the device 220, and at a fairly close range,
generally less that 1 meter, the IR ranging sensor 263 should yield
a reading indicative of a body at close range in front of the
device 220.
[0038] FIG. 3d shows the likely context variable values read when a
user is simply close to the device 220. In particular, the
proximity sensor 255 will detect the presence of the user within a
certain range of the device as discussed above. Thus, in the
situation where the user is close to the device 220 (such as close
enough to hear a ringer of reduced, or lower than normal ring
volume) the proximity sensor 255 should yield an output so
indicating. The touch sensor 261 and IR ranging sensor 263 may also
give a reading indicating touch and/or proximity in front of the
device 220 respectively, but such need not be the case. For
example, the user may have the device 220 resting untouched and
face down on a nearby table.
[0039] Note that the temperature sensor reading is not explicitly
used in the determinations of FIGS. 3A-D, but may be used to help
make a determination in certain ambiguous cases. For example, many
readings will be the same whether the device 220 is in a backpack
on the user's back or in a user's pocket. However, the temperature
sensor will probably detect a colder temperature when the device
220 is in the backpack because it will be more insulated from the
user's body heat. In contrast, the temperature reading while in the
user's pocket will be higher, and may approach body temperature in
some cases. Other ambiguous cases may also be solved by use of the
temperature sensor output. For example, a sudden change in
temperature may be used to indicate exit from or entry to a
building. In the case of entry to a building, the normal settings
for a moving device may apply, but in the case of leaving a
building, it may be assumed that access points will be fewer and
further between, and hence the registration frequency may be
decreased over what it may otherwise be for a device in otherwise
similar circumstances. Given the described architecture, those of
skill in the art will appreciate the myriad of other uses to which
the temperature sensor may be put.
[0040] The determination of whether a device 220 is moving, is in a
pocket, is being looked at, and/or is close to a user can be used
to modify the power consumption of the device 220, as will be
discussed hereinafter with reference to FIG. 4. FIG. 4 gives a
table linking observed device contextual properties to
modifications in device power consumption. In particular, columns
401, 403, 405, and 407 describe the state of a context variable,
while column 409 describes the resultant power consumption
modification techniques applicable given a particular set of
context variable values.
[0041] Beginning with row 411, it can be seen that the device 220
is not moving, is not in the user's pocket, is not being looked at
(at the screen), and is not close to the user. This set of context
variable values generally corresponds to the situation where the
device 220 has been set down somewhere, perhaps in the same room as
the user, but not very close to the user. In this situation, as
described in row 411 it is assumed that the device is not being
actively used, at least for outgoing communications, and hence the
device is placed in a low power standby mode, such as via a mode of
its primary wireless channel or via a secondary low power channel.
In addition, the ringer is set to high power so that the user has a
higher probability of hearing it if and when it is used, and the
vibrator is deactivated so that it will not actuate upon an
incoming communication, since the user is not close enough to feel
any vibration. Further, the screen is darkened since the user is
not close enough to use it, and the frequency of registration
updates to a wireless access point is set at a decreased rate since
the device is not moving, making a change in registration
unlikely.
[0042] With reference to row 413, it can be seen that the device
220 is not moving, is not in the user's pocket, is not being looked
at (at the screen), and is close to the user. This set of context
variable values generally corresponds to the same situation
described by row 411, except that the user is now closer to the
device 220. In this case, the power consumption behavior of the
device is changed from that described in row 411 by setting the
ringer to a lower volume setting, since the user is now closer to
the device 220, and should be able to hear a lower volume ringer
than when the user is further from the device 220.
[0043] Row 415 describes a combination of context variables that is
unlikely to occur absent a malfunction of one or more sensors. In
particular, row 415 describes a situation wherein the user is
looking at the screen but is not close to the device 220. As with
row 415, the context variable values represented in row 419 are
unlikely to occur absent a sensor failure. In particular, it is
unlikely that the device 220 would be in the user's pocket while
not being close to the user. Similarly, rows 423 (in pocket and
being looked at), 425 (same inconsistency as row 423), 431 (same
inconsistency as row 415), 435 (same inconsistency as row 415), 439
(same inconsistencies as rows 423 and 419), and 441 (same
inconsistency as row 423) describe unlikely combinations of context
variable values, and would most likely represent a sensor failure.
Thus, when the context variable value combinations in any of rows
415, 419, 423, 425, 431, 435, 439, and 441 occur, a visual or
audible signal is preferably conveyed to the user to indicate
probable sensor failure. Alternatively or additionally, the device
220 may enter a default mode of operation, such as the mode
described with respect to row 411.
[0044] The situation described by the context variable values
presented in row 417 most likely corresponds to a user standing
still, holding the device 220, while looking at the device screen.
In such a situation, the device 220 is preferably placed in a
normal mode ready to send and receive on the assumption that the
user will imminently send or receive information at that point.
Preferably, the screen is set to a normal display value rather than
being darkened or dimmed, and the ringer and vibrator are
deactivated since the user will likely detect any incoming call
simply by watching the device screen. Since the user is not moving,
the frequency of registration updates to a wireless access point is
set at a decreased rate.
[0045] With reference to row 421, it can be seen that the device
220 is not moving, is in the user's pocket, is not being looked,
and is close to the user. This set of context variable values
generally corresponds to the situation where the device 220 is in
the pocket of a user who is standing relatively still. In this
case, the power consumption affecting properties of the device are
modified so that the device is in a normal mode of operation, as
opposed to low power standby, the ringer is deactivated and the
vibrator activated, the screen is darkened (i.e. no power to the
screen), and the frequency of registration updates is set to a
decreased value.
[0046] With reference to row 427, it can be seen that the device
220 is moving, is not in the user's pocket, is not being looked at
(at the screen), and is not close to the user. This set of context
variable values is generally unlikely to occur, and could
correspond to a situation where the device 220 had been placed down
on a movable object such as an audio visual support cart. If this
situation were to occur, the power consumption behaviors described
with respect to row 411 would be appropriate, with the exception
that the registration update frequency should be at a normal rate
since the device 220 is moving.
[0047] The context variable value combination described in row 429
will generally occur when the user is holding the device 220 and
walking with it, without placing it in a pocket and without
observing the screen. In this situation, the device 220 is
preferably placed-in a normal power mode due to likely imminent
use, the ringer is set to a lower volume, the vibrator is
deactivated, the screen is darkened, and the registration update
rate is set to a normal rate as opposed to a decreased rate due to
the fact that the device 220 is moving.
[0048] With reference to row 433, it can be seen that the device
220 is moving, is not in the user's pocket, is being looked at, and
is close to the user. This set of context variable values generally
corresponds to the situation where the user is holding the device
220 and walking with it, while observing the screen. In this case,
it is preferable that the power consumption characteristics be set
as in row 417, with the exception that the update rate should be
set to normal rather than decreased since the device 220 is
moving.
[0049] Finally, the context variable value combination represented
in row 437 corresponds to a situation where the user is walking
with the device 220 in a pocket. In this situation, the power
consumption characteristics should be set as in row 421, except
that the update rate should be set to normal rather than decreased
since the device 220 is moving. In particular, the device 220
should be in a normal rather than low power stand by mode, should
have the ringer deactivated, the vibrator activated, the screen
darkened, and the registration update frequency set to normal
rather than decreased.
[0050] Information such as that corresponding to the table of FIG.
4 is preferably stored electronically in a table or other data
structure within the memory of the device 220. The exact format or
content of the information so stored is not critical, but it
preferably describes sets of power consumption variable responses
linked to various context variable value sets, so that the power
consumption of the device 220 is decreased on average by modifying
the behavior of the device according to the table in response to
the presence of certain context variable values.
[0051] Also note that the foregoing description of linking sensed
values to types of environmental conditions and ultimately to a
listing of power consumption variable settings is given for the
convenience of the reader and is not exhaustive. For example,
sensed value sets may be linked directly to listings of power
consumption variable settings. Additionally, it is not required
that the linkage between sensed values and listings of power
consumption variable settings be performed via a tabulated mapping.
For example, the linkage may be made by way of a formula or set of
formulae, whereby entry of the relevant sensed values or derived
environmental context conclusions yields an appropriate group of
power consumption variable settings. Thus it will be appreciated
that the given illustration is exemplary rather than
exhaustive.
[0052] Although the examples herein focus on specific power
consumption variables to be modified in response to measured
context variable value combinations, other power consumption
variables and context variables or values thereof may be used
alternatively or additionally without limitation. Furthermore, the
specific responses shown as responsive to certain context variable
value combinations are exemplary, rather than limitative. As such,
any other response of the same or other power consumption variables
may be used to reduce the power consumption of a device without
departing from the scope of the invention.
[0053] It will appreciated that a novel power management technique
and system have been disclosed for reducing power consumption in
mobile devices communicably linked to one or more other machines or
devices by controlling a plurality of power affecting behaviors. In
view of the many possible embodiments to which the principles of
this invention may be applied, it should be recognized that the
embodiments described herein with respect to the drawing figures
are meant to be illustrative only and should not be taken as
limiting the scope of invention. For example, those of skill in the
art will recognize that the elements of the illustrated embodiments
shown in software may be implemented in hardware and vice versa or
that the illustrated embodiments can be modified in arrangement and
detail without departing from the spirit of the invention.
Therefore, the invention as described herein contemplates all such
embodiments as may come within the scope of the following claims
and equivalents thereof.
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