Electrical computers and digital processing systems: support – Computer power control – Power conservation
Reexamination Certificate
1999-12-07
2003-06-03
Lee, Thomas (Department: 2153)
Electrical computers and digital processing systems: support
Computer power control
Power conservation
C713S320000, C713S340000
Reexamination Certificate
active
06574740
ABSTRACT:
BACKGROUND OF THE INVENTION
Pursuant to 35 U.S.C. 119, Applicants claim the benefits of Japanese Application No. 10-347278, which was filed of Dec. 7, 1998. This Japanese patent application and its translation are incorporated into this application by reference.
This invention relates to a technique for dynamically controlling power consumption of an electronic apparatus such as a computer or the like and, more particularly, to a method and an apparatus for use in a computer, which is provided with loads such as a central processing unit (CPU) and/or a display device each with its power consumption being adjustable, to dynamically control power consumption of a portion of the loads in accordance with a predicted result of maximum power consumption of the computer, thereby to limit its power consumption to a predetermined value or less.
In general, a portable computer (hereinafter simply called “computer”) has a smaller size and a lighter weight to enrich its portability and, thus, so long as it is equipped with a battery pack, it is adapted for use in any location where no AC power supply is available. Conversely, in a location where an AC power supply is available, an AC power adapter (hereinafter called “AC adapter”) is normally connected to an electric outlet of a commercial power supply for feeding DC power to system loads within the computer and for recharging its internal batteries. Thus, a user may bring an AC adapter whenever he/she carries his/her computer. Recently, functions and performance of a portable computer are being dramatically enhanced, and this results in a continuous increase in power consumption of a computer. Keeping pace with such a trend, capacity of an AC adapter is inclined to increase as well. Obviously, such an inclination is unfavorable to a portable computer that attaches importance to its portability.
Japanese Patent Publication No. 5-241769 discloses a technique for controlling maximum power consumption of a computer, whereby brightness of a display device of the computer may be increased to its maximum level within capacity of a given AC adapter. In this technique, when a user adjusts brightness of a liquid crystal display (LCD) to cause its load current to be changed, a charge control circuit is responsive thereto for automatically controlling charging time, thereby adjusting a current of the circuit. As a result, a sum of the currents for the LCD and charge control circuit is so controlled as not to exceed the capacity of the AC adapter, whereby the user is allowed to freely change the brightness within an adjustable range of the charging time.
With this technique, however, the charging time corresponding to the brightness of the LCD is so set up previously as not to exceed the capacity of the AC adapter, and when the user selects the brightness or power consumption of the LCD to be a certain value., the charging time or power consumption of the charge control circuit is caused to be adjusted accordingly. Since there exist one or more loads in the computer (which constitute the computer system) besides the LCD and the charge control circuit, power to be consumed thereby is fed from the AC adapter as well. Also, power consumption of the entire system load varies, depending on or in accordance with a particular operation being carried out by the computer. For example, when a CD-ROM drive is being accessed for reproducing any animation on the LCD, a larger amount of power is consumed, whereas in another case of creating a document with static images alone, a smaller amount of power is consumed.
In said technique, on a premise that power consumption of the system load is always equated with maximum power consumption, a combination of power consumption of the LCD and the charge control circuit has been set up such that power consumption of the entire computer is confined within the capacity of the AC adapter. However, since actual power consumption of the system load varies in accordance with an operating state of the computer as mentioned above, it is far less than the maximum power consumption. As a result, there occurs a waste of the capacity of the AC adapter in proportion to a difference between the maximum power consumption of the system load and actual power consumption. Further, this technique does not disclose any means for predicting the maximum power consumption of the computer, nor does it disclose any means for dynamically adjusting power consumption of a load in accordance with the predicted result.
Therefore, it is an object of this invention to provide a method and an apparatus for predicting maximum power consumption of an electronic apparatus and for dynamically controlling power consumption of a portion of its loads in response to the predicted result, thereby to limit its power consumption to a predetermined value or less.
It is another object of this invention to provide a method and an apparatus for predicting maximum power consumption of a computer and for temporarily changing a function of its CPU or LCD in response to the predicted result while the computer is operating to control its power consumption, thereby limiting its power consumption to a predetermined value or less.
It is yet another object of this invention to provide a method and an apparatus adapted for use in an electronic apparatus, which is fed power by a given AC adapter, for effectively making use of capacity of the adapter without needlessly increasing the capacity thereof.
SUMMARY OF THE INVENTION
Power consumption of an electronic apparatus such as a computer or the like varies in accordance with a type of its processed data or an operating state. This invention may be applied to an electronic apparatus, which includes a load with its power consumption being adjustable (hereinafter called “controlled load”) and a set of loads comprising a plurality of components (hereinafter called “base loads”). The controlled load has a plurality of operation modes corresponding to functional levels in such a manner that when the operation modes are switched or changed from one to another, maximum power consumption of the controlled load and its actual power consumption are varied accordingly. On the other hand, actual power consumption of the base loads is, in general, far less than a sum of maximum power consumption of each component, and this power consumption varies as a result of a change in an operating state of the electronic apparatus.
In one aspect of this invention, there is provided a method of controlling power consumption of a computer, which is provided with base loads comprising a plurality of components, and a CPU including a plurality of operation modes associated with power consumption thereof, the method comprising the steps of: obtaining predicted maximum power consumption of said computer from actual power consumption of said base loads and maximum power consumption in a current operation mode of said CPU; providing reference power; comparing said predicted maximum power consumption with said reference power; and changing the operation mode of said CPU in response to said comparing step. It is clear from the description of the present specification, however, that application of this invention is not limited to controlling of power consumption of a computer, since this invention is broadly applicable to controlling of power consumption of a conventional electronic apparatus as well. Also, the load including a plurality of operation modes associated with power consumption thereof is not limited to a CPU alone, since it may be any load so long as its power consumption is changeable, i.e., any member of the so-called “controlled loads”. Note here that the expression, “operation modes associated with power consumption”, refers to one or more operation modes of intermediate states (each being capable of consuming a certain amount of power) between the most active operation mode (wherein the controlled load consumes its maximum power) and the most inactive operation mode (wherein the controlled load is stopped), and that upon setting one of the operat
Naitoh Arimasa
Odaohhara Shigefumi
Barqadle Yasin
Bracewell & Patterson LLP
International Business Machines - Corporation
Lee Thomas
LandOfFree
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