Color Irregularity Correction - Sharp XG-V10WU Technical Manual

XG-V10WU
XG-V10WE

4-5. Color irregularity correction

[What is color irregularity?]
The phenomenon that color reproduction differs depending on the points on the screen of three-panel LCD projec-
tor.
It is conspicuous especially when displaying all white, all black or all gray screen.
When color irregularity occurs, the color appears to be different in different points on the screen even if it is to
display the same color on the whole screen.
[Causes of color irregularity]
What causes color irregularity with LCD projector can be classified mainly in the following 4 factors. The color
irregularity is caused by the combination of any of these factors.
» Factors related to LCD panel
1 Uneven liquid crystal layer thickness (panel cell gap distance)
2 Difference of aperture on the panel. Positional deviation of micro-lens bonded on the panel.
» Other factors than LCD panel
3 Optic axis deviation of lamp
4 Irregularity of optical components in the panel
1. Panel cell gap distance is not even on the
panel, which causes difference of V-T
characteristics at different points on the
panel.
2. Light path differs for each of R, G and B. The difference of
light intensity and chromaticity for each of R, G and B causes
color irregularity in white, a product of RGB synthesis.
[When color irregularity correction required]
The above mentioned factors 1 to 4 indicate that the color irregularity correction is imperative whenever the LCD
panel is replaced.
(It is not necessary at the time of lamp replacement.)
An example of the screen with color irregularity
(When displaying all gray screen)
Greenish at bottom left and bluish at top right
Point A
R component
G component
Spectrum
Lamp
B component
Intensity distribution of
R component
Low
High
Medium
42
Point B
LCD panel
Synthesis
Intensity distribution of Intensity distribution of
G component B component
Low Low
High
Medium
Medium
Color irregularity occurs
when synthesized
Point A
Point B
Drive voltage
Display
Lens
High