Browse Prior Art Database

A Method to Implement an Adaptive Power Management of Screen Off in ACPI OS Disclosure Number: IPCOM000014506D
Original Publication Date: 2001-Feb-01
Included in the Prior Art Database: 2003-Jun-19
Document File: 4 page(s) / 107K

Publishing Venue



*Title of disclosure

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A Method to Implement an Adaptive Power Management of Screen Off in ACPI OS

*Title of disclosure

A Method to Implement an Adaptive Power Management of Screen Off

*Idea of disclosure

This article describes a method of implementing an adaptive
screen off timer control with notification to the user before the
screen off time by the idle timer in ACPI OS environment.

Currently, if a PC is powered by the battery, to reduce
unnecessary power consumption, if there is no input from the
keyboard or an pointing device (like a mouse) for a certain
period of time, the output to the internal and external display
device will be disabled (Screen Off Timer). The duration of idle
timer is set by the user through the OS user interface and it is
not changed until the user set it to another value (Fig. 1).If
the idle timer value is too long, the unnecessary power
consumption is high however, if the timer is too short, it is
embarrassing. If the user is using the PC for the presentation,
user may speak more than the Screen Off Timer value without any
key or mouse input and the screen goes off. To prevent this
problem, there are some programs which set the PC to the
presentation mode and disable the Screen Off Timer, however, it
still needs the user to set and enable that mode. This article
describes the method to set the appropriate timer value by
considering the reaction of the user for a notification of the
timer expiration or the screen off event especially focused on
the presentation environment.




Fig.1 Standard Screen Off Timer

<Notification Methods>

There may be several ways to notify the user that the screen is
going off, such as beep or pop up message however, both methods
may be noticed by an audiences also. One of the methods we
selected here is to utilize the back light of the internal

Ti : Idle Time


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display screen since the internal screen might not be visible
from the audience. The program may turn off and on for a while
before the timer is expired or gradually decrease the brightness.
This may alert the presenter that the screen is going off
shortly. If the presenter noticed it, he/she should press a key
or move a pointing device to reset the idle timer.

<Changing the Screen Off Timer: Adaptive Power Management of
Screen Off Timer>

Even if the screen did not go off by pressing a key when the user
noticed the notification, it is not good to do the same thing a
while later. Or if the presenter did not noticed the
notification and the screen went off, it is better to extend the
Screen Off Timer more to prevent the next screen off. Fig. 2
shows the concepts of the adaptive power management algorithm.
The next Screen Off Timer value (Next Idle Time) Tni is defined
by considering the value of previous Screen Off Timer value (Idle
Ti (Ti=Tfi + Tdi) and the duration of Scre...