Field sequential color display device with red, green, blue and white light sources
View Patent ↗An highly bright and energy efficient FSC color liquid crystal display device incorporating a white light source is provided. The FSC color display device includes a first light source for emitting a light having a plurality of colors, a second light source for emitting a white light, and a light source controller for displaying a color image so as to control the first light source to repeat, in a predetermined cycle, sequentially making a selection from the plurality of color light sources to cause the selected color light source to emit a light, and to control the second light source so that the second light source emits a white light concurrently with light emission from the first light source.
1. A color display device employing a field sequential color (FSC) system, comprising:
a liquid crystal panel;
an R-color light source for emitting red light;
a G-color light source for emitting green light;
a B-color light source for emitting blue light;
a W-color light source for emitting white light;
a light guiding means for illuminating the liquid crystal panel with light emitted by the R-color, G-color, B-color, and W-color light sources; and
a light source controller for controlling the R-color, G-color, B-color, and W-color light sources to:
display a color image by sequentially activating the R-color, G-color, and B-color light sources to emit light in respective subfields in a predetermined cycle, each of the subfields lasting for a predetermined duration, and
display a monochrome image by activating the W-color light source to emit light in subfields corresponding to subfields of the predetermined cycle,
wherein the light source controller controls the W-color light source so that:
an apparent brightness of white light emission during a subfield corresponding to the R-color subfield is equal to the apparent brightness of the R-color light emitted during the R-color subfield;
an apparent brightness of white light emission during a subfield corresponding to the G-color subfield is equal to the apparent brightness of the G-color light emitted during the G-color subfield; and
an apparent brightness of white light emission during a subfield corresponding to the B-color subfield is equal to the apparent brightness of the B-color light emitted during the B-color subfield.
2. The color display device according to claim 1 , wherein the light source controller controls the R-color, G-color, B-color, and W-color light sources to display the monochrome image by stopping the R-color, and B-color light sources, and emitting light from only the W-color light source.
3. The color display device according to claim 2 , further comprising a receiver for receiving a signal for switching between a first mode for displaying the color image and a second mode for displaying the monochrome image.
4. The color display device according to claim 1 , wherein the light source controller controls a ratio between an ON period of the R-color, G-color, B-color, and W-color light sources and an OFF period of the R-color, G-color, B-color, and W-color light sources.