Liquid-crystal display and signal converting circuit

A liquid crystal display device comprising:

• a liquid crystal display panel including a pixel defined by a plurality of subpixels;
• and
• a driving circuit configured to supply display signals to the plurality of subpixels of the pixel;
• wherein
• the plurality of subpixels include a red subpixel, a green subpixel, a blue subpixel, and a yellow subpixel;
• in the pixel, the plurality of subpixels are divided into:
• a first subpixel group including the yellow subpixel and one of the red subpixel and the green subpixel;
• and
• a second subpixel group including the blue subpixel and the other of the red subpixel and the green subpixel;
• and
• in the pixel, to display achromatic colors having at least some grayscale levels among all grayscale levels, the driving circuit is configured to supply:
• to the subpixels of the first subpixel group, display signals of a same grayscale level;
• and
• to the subpixels of the second subpixel group, display signals of a different grayscale level from the grayscale level of the display signals supplied to the first subpixel group;
• with respect to an achromatic color of a given intermediate grayscale level among the at least some grayscale levels being displayed by the pixel, xy chromaticity coordinates of an achromatic color displayed by the pixel when assuming that display signals of the same grayscale level as the given intermediate grayscale level are supplied to all of the plurality of subpixels is defined as a reference chromaticity point;
• xy chromaticity coordinates of an achromatic color of a highest grayscale level displayed by the pixel is defined as a target chromaticity point;
• and a locus of the reference chromaticity point on an xy chromaticity diagram when the grayscale level of the display signal supplied to the blue subpixel is increased or decreased is defined as a B axis;
• when the target chromaticity point is located above the B axis on the xy chromaticity diagram, the first subpixel group includes the yellow subpixel and the red subpixel, the second subpixel group includes the blue subpixel and the green subpixel, the driving circuit supplies a driving signal to the blue subpixel having a lower grayscale level than the grayscale level of the display signals supplied to the yellow subpixel and the red subpixel, and the driving circuit supplies a driving signal to the green subpixel having a higher grayscale level than the grayscale level of the display signals supplied to the yellow subpixel and the red subpixel;
• and
• when the target chromaticity point is located below the B axis on the xy chromaticity diagram, the first subpixel group includes the yellow subpixel and the green subpixel, the second subpixel group includes the blue subpixel and the red subpixel, the driving circuit supplies a drive signal to the blue subpixel having a lower grayscale level than the grayscale level of the display signals supplied to the yellow subpixel and the green subpixel, and the driving circuit supplies a driving signal to the red subpixel having a higher grayscale level than the grayscale level of the display signals supplied to the yellow subpixel and the green subpixel.

A signal conversion circuit for use in a liquid crystal display device to convert an image signal corresponding to three primary colors into a multiprimary signal corresponding to four primary colors, the liquid crystal display device including a pixel which is defined by a red subpixel, a green subpixel, a blue subpixel, and a yellow subpixel;

• wherein
• in the pixel, the subpixels are divided into:
• a first subpixel group including the yellow subpixel and the green subpixel;
• and
• a second subpixel group including the blue subpixel and the red subpixel;
• in the pixel, to display achromatic colors of at least some grayscale levels among all grayscale levels, the signal conversion circuit is configured to convert the image signal so that:
• the yellow subpixel and the green subpixel of the first subpixel group displays at a same grayscale level;
• the blue subpixel of the second subpixel group displays at a lower grayscale level than the grayscale level of the yellow subpixel and the green subpixel of the first subpixel group, and
• the red subpixel of the second subpixel group displays at a higher grayscale level than The grayscale level of the yellow subpixel and the green subpixel of the first subpixel group.