Browse Prior Art Database

Backlight Control Method for Liquid Crystal Display

IP.com Disclosure Number: IPCOM000112384D
Original Publication Date: 1994-May-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Hirano, Y: AUTHOR [+3]

Abstract

Disclosed is a method for controlling a brightness of a backlight used in a Liquid Crystal Display (LCD) which is a battery driven system. The object of the method is to reduce the power consumption and to keep the battery life longer. The brightness is controlled in accordance with battery remains. The LCD backlight component has a special low power mode to cut off its power consumption. When the system battery remains are in a lower state, such mode will be entered. With a sacrifice of screen visibility, the system will work longer even with a discharged battery.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Backlight Control Method for Liquid Crystal Display

      Disclosed is a method for controlling a brightness of a
backlight used in a Liquid Crystal Display (LCD) which is a battery
driven system.  The object of the method is to reduce the power
consumption and to keep the battery life longer.  The brightness is
controlled in accordance with battery remains.  The LCD backlight
component has a special low power mode to cut off its power
consumption.  When the system battery remains are in a lower state,
such mode will be entered.  With a sacrifice of screen visibility,
the system will work longer even with a discharged battery.

      In addition to this low power mode of LCD backlight component,
the LCD screen auto-dim time in accordance with no activities of the
input device (e.g., keyboards, pointing devices) is decreased by
switching on and off its backlight power according to the battery
remains.  As a result of it, the mean power consumption of the LCD
component is decreased and it helps the battery life longer.

The hardware requirements for this method are as follows:

1.  Intelligent battery which is able to report the battery remains
    or the information to be used for calculation of remains.

2.  LCD Backlight Component which is able to change the brightness by
    program.

      Control processes are described in Figs. 1 and 2.  Fig. 1 shows
a Input Device Interrupt Process.  Fig. 2 shows a Periodic Timer
Interrupt Process.