Patent ID: 7982706

Claim:
A backlight device having a plurality of light emitting diodes of at least three colors as a light source, the backlight device synthesizing light emitted from the light emitting diodes of each color to produce white light and emitting the produced white light from a backside of a display unit, the backlight device comprising: a temperature sensor that senses temperature of the light source; drive control means that supplies a current to the light emitting diodes of each color to drive the light emitting diodes; and storage means that stores an initial current amount for the light emitting diodes of each color and a correction amount for the initial current amount, the correction amount depending on temperature, wherein the drive control means calculates, upon powering on the backlight device, the correction amount based on a value sensed by the temperature sensor, the drive control means adding the calculated correction amount to the initial current amount of the light emitting diodes of each color and activating the light emitting diodes of each color with a corrected initial current amount, the light emitting diodes as the light source are light emitting diodes of red, green and blue, and the drive control means implements feedback control, based on chromaticity of the white light using the light emitting diodes of blue as a reference, such that an amount of current flowing through the light emitting diodes of blue is fixed at a constant value while amounts of currents flowing through the light emitting diodes of red and green are varied, so that the white light has a certain chromaticity, wherein the constant value is the corrected initial current amount with which the light emitting diodes of blue are activated, and the corrected initial current amounts with which the light emitting diodes of red and green are activated are based on respective current value differences of the light emitting diodes of red and green and a sensed temperature of the light source, wherein the current value difference of the light emitting diodes of red is determined by subtracting, from the initial current amount for the light emitting diodes of red obtained at a predetermined temperature, a current amount for the light emitting diodes of red when the chromaticity of the emitted light is the certain chromaticity at a different predetermined temperature, and the current value difference of the light emitting diodes of green is determined by subtracting, from the initial current amount for the light emitting diodes of green obtained at the predetermined temperature, a current amount for the light emitting diodes of green when the chromaticity of the emitted light is the certain chromaticity at the different predetermined temperature.