White Balance Control Method on Liquid Crystal Display
Original Publication Date: 1994-Nov-01
Included in the Prior Art Database: 2005-Mar-27
Publishing Venue
IBM
Related People
Kimura, Y: AUTHOR [+3]
Abstract
Abstract: Disclosed is a device for controlling a white balance on Thin Film Transistor Liquid Crystal Display (TFT LCD) screen. To control the color, several Cold cathode Fluorescent Lamp (CFLs) which have different color spectrum each other are used. By this mixing of color, white balance on TFT LCD screen is adjusted by both local and remote controls.
White Balance Control Method on Liquid Crystal Display
Abstract: Disclosed is a device
for controlling a white
balance on Thin Film Transistor Liquid Crystal Display (TFT LCD)
screen. To control the color, several
Cold cathode Fluorescent Lamp
(CFLs) which have different color spectrum each other are used. By
this mixing of color, white balance on TFT LCD screen is adjusted by
both local and remote controls.
Contents: This method consists of
side edge type backlight
unit to have several CFL lamps. Each of
Fig. 1 and 3 shows a plane
view of side edge type backlight. Fig. 2
shows an A-A cross
sectional structure of the backlight.
The side edge type backlight
unit contains CFL lamps 1, lamp holders 2, light guide (acrylic
plate) 3, diffusing sheet 4, and power unit (inverter) 5. Inverter 5
has a brightness control circuit 7 and transformers 6. In Fig. 3,
photo sensor 8 which is used for automatic color control is shown.
In case of
local control in backlight unit, lamp current is
controlled by an inverter 5. The ratio
of mixing color is done by
controlling each CFL current independently by this inverter. Each
CFL lamp has set up the different spectrum of lamp. For example, one
lamp is a white lamp and has biased to green spectrum by small
amount, the other lamp has biased to red spectrum. If the green
biased lamp gets more current than red biased lamp, then the TFT LCD
screen color (white balance) goes to a little bit of...