A variably controlled LCD backlight is disclosed. The backlight includes a first light source that emits light within a first spectral power distribution and has a first radiant power output. A second light source emits light within a second spectral power distribution and has a second radiant power output. A detector detects the first and second radiant power outputs. A processor is connected to the detector and calculates chromaticity and luminance values of the emitted light based on the first and second radiant power outputs. The processor compares the calculated chromaticity and luminance values with desired chromaticity and luminance values, respectively. A controller is operationally connected to the processor and adjusts one or more of the first radiant power output and the second radiant power output in response to a difference between the calculated chromaticity and luminance values and the desired chromaticity and luminance values.
Color correction of Liquid Crystal Display (LCD) lighting in response to the color balance of ambient illumination. In response to the color balance of sensed ambient illumination, drive levels of light emitting diodes providing lighting to the LCD are changed.
A back-light apparatus for a display includes: a plurality of light emitting diodes attached on a substrate; a first common line mounted on the substrate to commonly connect first electrodes of the light emitting diodes; a second common line mounted on the substrate to commonly connect second electrodes of the light emitting diodes; a plurality of third lines connected to preceding second electrodes of the light emitting diodes and succeeding first electrodes of the light emitting diodes; first and second selection switches disconnecting the first common line and the second common line so that the light emitting diodes are connected in parallel; third selection switches for disconnecting the third lines so that the light emitting diodes are connected in series; a power unit to supply power to the light emitting diodes; and a control unit to control the first, second and third selection switches for the light emitting diodes.
A backlight module (20) includes a light guide plate (200) and a light source (10). The light guide plate includes a light incident surface (220) opposite to the light source. The light source includes a plurality of multicolor based LEDs (120) and the LEDs each includes a plurality of LED chips (120A/B/C). The light source can achieve colored light beams with fewer LEDs, and no color filter is needed in the backlight module or a liquid crystal display using the light source. Thus, the cost of the backlight module can be reduced.
A description is given of an illumination device which emits mixed-color light containing light of at least two different color channels (R, R1, G, G1, B, B1). The illumination device contains at least one primary light source (1) of a first color, the light of which forms a first color channel (R, R1, G, G1, B, B1), and at least one primary light source (1) of a second color, the light of which forms a second color channel (R, R1, G, G1, B, B1), at least one sensor device (3), which is positioned such that it can receive mixed-color light and is suitable for detecting brightness of light of a wavelength range comprising the color channels (R, R1, G, G1, B, B1) and which determines the brightnesses of the different color channels (R, R1, G, G1, B, B1) separately and repeatedly during operation. Furthermore, the illumination device contains an evaluation and control device (4), which evaluates the brightness values of the color channels (R, R1, G, G1, B, B1) and determines pulse-width-modulated electrical signals with a basic period (11) modified in such a way for the driving of the individual color channels (R, R1, G, G1, B, B1) in such a way that the color location of the mixed-color light lies within a predetermined region of the CIE standard chromaticity diagram. A method is also described for controlling such an illumination device.
