Patent ID: 7940354

Claim:
A liquid crystal display device comprising: a white light source provided with a blue phosphor that emits blue light, a green phosphor that emits green light, and a red phosphor that emits red light; and a liquid crystal display panel having color filters to adjust the amount of transmitted light from the white light source for every pixel and transmit any one of blue, green, and red lights for every pixel, wherein the white light source includes an airtight tube provided with the blue phosphor, the green phosphor, and the red phosphor, electrodes arranged at respective ends of the airtight tube, and a discharge medium sealed in the airtight tube, and the airtight tube is a cylindrical glass tube having an inner diameter less than or equal to 10 mm, wherein, during operation of the white light source, the airtight tube has higher temperatures at its respective ends where the electrodes are arranged relative to a center portion of the airtight tube between the electrodes, wherein the white light source is disposed behind a back side of the liquid crystal display panel such that portions of the airtight tube are within an area defined by a periphery of the liquid crystal display panel, and wherein, in order to compensate for a brightness distribution of the white light source caused by a temperature dependence of the red phosphor on temperature variations of the airtight tube, the red phosphor is selected to be represented by a composition formula (Y 1-x-y , Gd x , Eu y ) 2 O 3 and the values of composition ratio, x and y, satisfy the conditions of 0.45≦x≦0.85 and 0.025≦y≦0.040, respectively.