WO2007071919A1

WO2007071919A1 - Low power mode operation in a computing device

Info

Publication number: WO2007071919A1
Application number: PCT/GB2006/004613
Authority: WO
Inventors: David Mccolgan
Original assignee: Symbian Software Limited
Priority date: 2005-12-21
Filing date: 2006-12-11
Publication date: 2007-06-28
Also published as: GB2433612A; GB0526039D0

Abstract

A computing device operable from an internal battery source is provided with the ability to discriminate between functionality that has been or can be categorised as essential and functionality that has been or can be categorised as non-essential. The device is thereby able to prolong its ability to carry out its core functionality by progressively restricting access to non-essential functionality of the computing device as its battery power decreases.

Description

Low Power Mode Operation in a Computing Device

This invention relates to the operation of a computing device in a low power mode, and in particular to a method of operating a computing device in one or more low power modes which also protects the core functionality of the computing device.

The term 'computing device' includes, without limitation, Desktop and Laptop computers, Personal Digital Assistants (PDAs), Mobile Telephones, Smartphones, Digital Cameras and Digital Music Players. It also includes converged devices incorporating the functionality of one or more of the classes of device already mentioned, together with many other industrial and domestic electronic appliances.

It is further possible to categorise computing devices according to their mobility and power source:

• Certain categories of computing devices are highly mobile; this means that they are designed to be used at any time in any place, even while on the move. Such devices invariably use batteries for power. This includes all mobile telephones and digital cameras, many mobile digital music players such as the Apple iPod, and many games machines such as the Nintendo Gameboy. It is usually possible to also operate such devices on mains power (via battery chargers or auxiliary low voltage power supplies) without consuming power from and therefore -" ^r draining the internal power battery source. However, such uses are generally considered to be atypical for such devices because their inherent portability and the ability to provide portable computing power is a major attraction for this type of device.

• Other types of computing device, notably laptop computers, are portable rather than truly mobile; that is to say, they are typically carried from one place of use to another place of use, rather than being operated while their user is actually mobile. While such devices include an internal battery power source and are often operated from this, they may equally be used with mains power; though since the battery life is inherently limited to a few hours of use because the device power consumption is relatively high, most users prefer to use mains power whenever it is available to them at a place of use.

• Even fixed computing devices, such as desktop computers, which in the context of this invention may be regarded as neither mobile nor portable, can be run on battery power; many manufacturers offer battery-powered UPSs (Uninterruptible Power Supplies) enabling them to carry on operating if the mains supply unexpectantly fails for some reason.

There are some hardware features adopted by portable and mobile devices that are designed to prolong battery life, such as:

• all or part of the device going into hibernation or sleep or other low power mode after a certain period of user inactivity; this is common on all devices using battery power, including laptops, mobile phones, PDAs, and digital cameras.

• dimming of any backlight after a certain period of use; again, this is common on mobile phones, digital cameras and digital music players.

Many devices which are designed to operate under both mains and battery power are also capable of automatically modifying certain hardware behaviours depending on the power source being used. Examples of these power saving measures are:

• a reduction of the intensity of the screen display on laptop computers when they are running on battery power.

• the adoption of more stringent hardware power settings on laptop computers, such that all or part of the device goes into hibernation or sleep or other low power mode more rapidly when used in battery power mode. It is also known for computing devices to automatically inform their users when running on battery power if the battery power is tending towards a critical level where device operation failure is considered imminent if remedial action is not taken. This is handled via the normal Ul (User Interface). The most common manifestation of this is the audible or visible low power warning that many such devices emit to inform the user that power is low and has reached a critical level.

Mobile phones normally restrict themselves to displaying a low power warning with an audible beep or other alarm. Some devices which normally emit audio adopt the reverse strategy and cease emitting audio when displaying low power warning.

More drastically, laptop users who are considered in danger of losing work through an impending battery power failure are often prompted either to switch to mains power or else to save any work in progress and switch off to avoid data loss. The most extreme case of this type of behaviour is to be seen on a desktop computer making use of an uninterruptible power supply (UPS) where the activation of the UPS can trigger a signal to the computing device to enter an emergency shutdown, similar to the user requesting a normal shutdown, with all applications being closed and all work saved before actual device switch-off.

In essence, therefore, the known forms of power management of computing devices running on batteries can be considered to be limited to some fairly coarse power saving operations:

• It is known that a computing device running on battery power can modify certain hardware settings to prolong battery life. • It is also known that computing devices can warn of impending battery failure, with the degree and type of warning varying from device to device.

• It is also known that computing devices can, under circumstances of imminent battery failure, force an orderly shut down and power off of the device.

However, there is nothing in the previously disclosed forms of power management that teaches or suggests how a computing device might be able to manage power resources more effectively and with a greater degree of control by managing the functionality available to the user of the computing device under various levels of battery condition.

Accordingly, it is an object of the present invention to provide an improved form of power management in a computing device which enables a greater degree of control by selectively managing the functionality available to the user of the computing device under various levels of battery condition.

According to a first aspect of the present invention there is provided

According to a second aspect of the present invention there is provided

According to a third aspect of the present invention there is provided

Embodiments of the present invention will now be described, by way of further example only.

The perception behind this invention is that a computing device which is able to discriminate between functionality that has been or can be categorised as either essential or non-essential can also prolong battery life by progressively restricting access to the non-essential functionality of the computing device in dependence upon its available battery power.

A compelling example of this invention is its application to mobile telephones running on cellular networks, and the invention is described here as it can be implemented on such devices. However, it should be noted that this particular implementation is not intended to limit the scope of the invention in any way, and that once the basic concept behind this invention has been explained, its extension to other computing devices in addition to mobile telephones is evident to those skilled in the art.

As described above, many classes of computing devices are increasingly converging, with functionality previously restricted to one class of device being made available as supplementary functionality on other classes of device. Mobile telephony handsets are a good illustration of this invention because they are probably the clearest example of a computing device manifesting this converging trend.

In addition to making and receiving telephone calls, mobile telephony handsets are now often used to provide some or all of the following examples of functionality (in no particular order or priority):

• sending and receiving text messages over short message services (SMS)

• recording and displaying digital photographs

• recording and displaying video clips

• transmitting or receiving digital photographs or video clips over multimedia messaging (MMS)

• listening to analogue or DAB radio

• listening to music stored digitally on the device, usually

• browsing the Internet

• composing, sending, receiving and reading electronic mail

• playing games • data entry and retrieval, such as using the telephone's address book

• calculating mathematical functions

• calendar, agenda and alarm clock

• using the backlight as a torch

• acting as a speakerphone

• to provide positioning or navigation information through the use of technology such as the Global Positioning System (GPS)

Note that this is just a selection of the functionality available on advanced mobile handsets today; many other applications are also possible, and new functionality is now becoming available on an ever increasing basis.

However, despite all the functionality available, it is likely that most people would, under most circumstances, regard the making and receiving of telephone calls as the most essential functionality for the device, and which should be protected as the highest functional priority. Working on this assumption, the present invention in its simplest form involves marking the making and receiving of telephone calls as essential functionality, with all other applications available on the device being marked as non-essential functionality. The user of the handset is then prevented from using any nonessential functionality whenever the power remaining in the battery on the device has reduced to less than a preset threshold. Non-essential applications that are running at the time the threshold is reached are then closed down, ideally after a prompt giving the user a short period of grace equivalent to something like a small extra percentage of battery level to exit in a controlled fashion; and after the threshold has been passed, no nonessential applications are permitted to start or re-start, or to continue to run.

In this way, the essential functionality of the device is protected to the greatest extent possible and the time that the device is to remain operational on a single battery charge, in respect of this essential functionality, is maximised. It is preferable that most users are able to decide for themselves what is essential functionality, so a user can add (as examples) SMS or email to the list of applications that are permitted to run when this critical power level has been reached. However, it is also envisaged that under some circumstances, the list of applications can be selectively password protected; this would, for example, enable a parent providing a mobile phone to their child (so that an essential communication channel is available between the parent and child) can ensure that the battery does not become unnecessarily drained by the child using the handset for purposes considered as non essential to the parent, such as playing computer games. It is also possible that some manufacturers of devices may decide to preset such a scheme during production, as a default factory setting.

In a more advanced implementation of this invention, the binary distinction between essential and non-essential applications, and the single setting of a preset battery level, may be relaxed in favour of a more flexible approach. In this implementation of the invention, applications are ranked in bands from the most essential to the least essential, with each band being associated with a particular battery level below which respective levels of essential functionality are not permitted to run.

For example, using the phone applications listed above, a possible scheme for a business user might be:

• battery level below 10%: only making and receiving telephone calls and addressbook lookup allowed

• battery level below 20%: text messaging, electronic mail calendar, addressbook entry, access to agenda and alarm clock additionally allowed

• battery level below 30%: web browsing, digital photography, video and MMS additionally allowed

• battery level below 40%: speakerphone, listening to FM radio and digital music additionally allowed • battery level below 45%: playing games, using a calculator, using the backlight as a torch additionally allowed

• battery level above 50%: all functionality allowed.

It is preferable for the scheme to allow for some hysteresis banding about the sensed battery levels to prevent unnecessary 'hunting' about any of the battery level thresholds. This is to ensure that if any battery level threshold is reached, whereby certain functions are enabled, those functions are not almost immediately or prematurely disabled again because the battery level drops back below the particular threshold because of the particular functionality that has just been enabled. Such power-saving schemes may be linked to other information available to the phone; for example, it might be deemed appropriate to switch to a scheme wherein the ability to use the backlight as a torch becomes essential functionality during the hours of darkness, but if the battery power is closer to a critical level then the use as a torch is restricted to a pulsed light mode to further reduce power consumption.

Remaining with the mobile telephone as an example, this innovation can be further extended to power-consuming aspects of the user interface. At a specific power level, battery life may be selectively conserved by switching to a special low-power Ul which disables animations, uses simpler icons, reduced backlight level and the time for which the backlight is active, and disables all audio prompts (with the exception of those relating to essential applications such as ring tones). The visible difference in the low power mode user interface has the additional advantage that it is made very clear to the user that the phone has reached a low power condition and needs recharging.

More refinements can include restricting access to power-hungry peripherals; so, for example, at a certain power level access to a hard disk is inhibited, but access to solid-state memory is allowed. Preferably, a preferred implementation of such a scheme should ensure that:

• the computing device incorporates an Operating System (OS) which is responsible for launching and managing applications that run on the device;

• the OS is responsible for maintaining, managing and providing the necessary interfaces to the hardware on the device and one of these interfaces includes a means of retrieving the current battery level;

• the list of essential and non-essential applications, and the relevant battery trigger level or levels, are stored in the device in a database or similar type of store

• that part of the OS which functions as an application launcher, before launching any application, first consults the database to see the associated trigger level for the application to be launched and then looks up the current battery level - if the current level is below the respective trigger level for that application, the launcher refuses to start the application (preferably with a suitable user prompt);

• that part of the OS which is responsible for scheduling threads of execution, before scheduling any thread, first consults the database to see the associated trigger level for the application which it was associated, and then looks up the current battery level - if the current level is below the trigger level, the scheduler either refuses to schedule the thread or else sets a suitable signal for the application or process owning it to be shut down (possibly after a suitable warning had been given, as outlined above). It should be noted that a refusal to schedule the thread means that if the battery is recharged, the application will automatically become available again, but in cases where the thread is closed down, the application will have to be restarted.

The exact details of an implementation of this invention will of course vary with any particular operating system; it will be apparent to those skilled in the art of programming any specific operating system running on a computing device how the outline above can be implemented on that device. It should also be noted that as well as its applicability to battery-operated devices, this invention can be implemented in any situation in which power is considered to be an especially scarce resource. For instance, solar-powered computing devices can use the methodology of this invention to restrict functionality to essential services in situations of low sunlight; or sites with multiple computing devices sharing the same mains generator could use the invention to implement a site policy controlling power consumption by the devices if there is limited generating capacity.

It can be seen from the above description that several advantages accrue through the use of the present invention. A key advantage of this invention is that it maximises the protection of the core functionality and purpose of a multi-function computing device, whatever that is selected to be. This can be important; for example, implementing this invention on a mobile telephone would help to ensure that calls to the emergency services are not made prematurely impossible because of over-enthusiastic use of non-essential functions, such as the playing of addictive games.

The invention also saves power by discouraging non-core uses for a multifunction computing device. Any measure that promotes power saving provides environmental benefits in general.

Although the present invention has been described with reference to specific embodiments, it should be realised that modifications can be effected whilst remaining within the scope of the invention as defined by the appended claims.

Claims

Claims:

1. A method of operating a computing device comprising restricting access to applications and functionality in dependence upon the power level available from a power resource of the device.

2. A method according to claim 1 wherein the computing device is powered, either individually or in combination, by any of a. chemical or other type of battery; or b. solar energy such a photovoltaic cells; or c. any type of electrical generator; or d. any other comparable electrical source.

3. A method according to claim 1 or claim 2 wherein certain applications and/or functionality available to the device are categorised a. as either essential or non-essential; or b. on a continuous or discontinuous scale reflecting different degrees of essentialness.

4. A method according to claim 3 wherein the categorisation of applications and/or functionality can be performed, either individually or in combination, by any of a. one or more users of the device; or b. the owner of the device; or c. the manufacturer of the device; or d. the provider or owner or controller of the electrical power source; or e. by the computing device itself, in response to any external event or trigger (including but not limited to time or location or a received message or user input) according to rules, instructions or procedures previously set out by the user, owner, or manufacturer of the device or the provider or owner or controller of the electrical power source.

5. A method according to claim 3 or claim 4 wherein each of the categorisations of essentialness, whether binary or on a scale, is associated with a level or threshold of power resources.

6. A method according to claim 5 wherein the level or threshold of power resources to be associated with any categorisations of essentialness is provided by any of a. one or more users of the device; or b. the owner of the device; or c. the manufacturer of the device; or d. the provider or owner or controller of the electrical power source.

7. A method according to any one of claims 4 to 6 wherein access to the said categorisations or the said level or threshold of power resources is available only on provision of a password or other authentication.

8. A method according to any one of the preceding claims wherein the computing device is enabled to obtain the current level of power resources available to it.

9. A method according to claim 8 wherein access to any applications and/or functionality is allowed or disallowed by means of a comparison between the current level of power resources available to the device and the level associated with the categorisation of essentialness of that application and/or functionality, on the basis that if the current level of power resources is the greater then access is permitted but if current level of power resources is the lesser then access is refused.

10. A method according to claim 9 wherein access comprises either a. the launching of an application; or b. the scheduling of a thread of execution; or c. the granting of access to a resource, whether by opening it or passing a handle to it or making a request of it or any other means.

11.A method according to claim 10 wherein refusal to schedule a thread of execution causes the application or process which owns that thread to be a. shut down; or b. scheduled to be shut down, with or without a warning to the user of the device, either after a period of time or after the current level of power resources available to the device has fallen by a further amount.

12. A method according to any one of the preceding claims wherein the computing device is selected to comprise a mobile telephone.

13.A method of any of the preceding claims wherein the applications and/or functionality include but are not limited to any of a. sending and receiving text messages over SMS b. taking and displaying digital photographs c. taking and displaying video clips d. transmitting or receiving digital photographs or video clips over MMS e. listening to analogue or DAB radio f. listening to digital music g. browsing the Internet h. composing, sending, receiving and reading electronic mail i. playing games j. data entry and retrieval, such as using the telephone's address book k. using a calculator I. calendar, agenda and alarm clock m. using the backlight as a torch n. acting as a speakerphone o. utilising positioning technology such as the GPS

14. A method according to any one of the preceding claims wherein the applications and/or functionality comprise any or all of the elements of user interface.

15.A method according to claim 14 wherein the computing device is automatically enabled to use an alternative user interface or any method thereof should access to the existing user interface be disallowed, and wherein automatic reversal to the disallowed user interface occurs when it once again becomes allowed.

16.A method according to any one of the preceding claims wherein the functionality comprises access to a peripheral of the computing device including but not limited to a disk drive or external speaker.

17.A computing device arranged to operate in accordance with a method as claimed in any one of claims 1 to 16.

18.An operating system for causing a computing device to operate in accordance with a method as claimed in any one of claims 1 to 16.