Color shading correction device and luminance shading correction device

A color shading correction device used in a liquid crystal display device which has a plurality of LCD panels, modulates the color lights coming into each of the LCD panels according to the video signals and synthesizes the modulated color lights, comprising:

• a timing circuit to generate a timing signal required for displaying the picture on said plurality of LCD panels,
• a plurality of signal processing circuits to input the video signals for modulating the color lights on said plurality of LCD panels, to process each of the video signals so as to supply them as the video signals suitable to each of said LCD panels,
• a plurality of correction circuits to approximate the luminance shading characteristics caused on said plurality of LCD panels in which each of said correction circuits includes a correction signal generating circuit to generate said correction signal for correcting the luminance shading which is caused due to the difference in thickness of said LCD panels under the control of said timing circuit, a low-pass filter which removes the high frequency range components from the video signal for the LCD panels where luminance shading corrections are performed and outputs the low frequency range components only, and a circuit to multiply said correction signal and the low frequency range components from said low pass filter to modulate and output said correction signal to be added so that the correction amount is increased when the level of the video signal is high, and the correction amount is decreased when the level of the video signal is low;
• and
• a plurality of adder circuits to add said correction signals, to which said correction amount is adjusted, to the voltages supplied to the pixel common electrodes on each of said LCD panels where luminance shading corrections are performed.

A luminance shading correction device for the LCD panel comprising:

• an LCD panel,
• a timing circuit to generate a timing signal required for displaying a picture on said LCD panels,
• a video signal input terminal,
• a signal processing circuit to process video signals inputted to said input terminal and to supply them as the video signals suitable to said LCD panels, and
• a correction circuit to add the correction signal to the video signal supplied to said LCD panel so as to approximate the luminance shading characteristics caused on said LCD panel, said correction circuit including a correction signal generating circuit to generate said correction signal for correcting the luminance shading which is caused due to the difference in thickness of said LCD panels under the control of said timing circuit, a low-pass filter which removes the high frequency range components from the video signal before the addition of said correction signal and outputs the low frequency range components only, and a circuit to multiply said correction signal and the low frequency range components from said low pass filter to modulate and output said correction signal to be added so that the correction amount is increased when the level of the video signal is high, and the correction amount is decreased when the level of the video signal is low.

A luminance shading correction device for the LCD panel comprising:

• an LCD panel,
• a timing circuit to generate a timing signal required for displaying a picture on said LCD panel,
• a video signal input terminal,
• a signal processing circuit to process video signals inputted to said input terminal so as to supply them as the video signals suitable to said LCD panel;
• and,
• a correction circuit including a correction signal generating circuit to generate a correction signal for correcting the luminance shading which is caused due to the difference in thickness of said LCD panels under the control of said timing circuit, a low-pass filter which removes the high frequency range components from the video signal supplied to said LCD panel and outputs the low frequency range components only, and a circuit to multiply said correction signal and the low frequency range components from said low pass filter to modulate and output said correction signal to be added so that the correction amount is increased when the level of the video signal is high, and the correction amount is decreased when the level of the video signal is low;
• and
• an adder circuit to add said correction signal, to which said correction amount is adjusted, to the voltages supplied to the pixel common electrode on said LCD panel.