Patent ID: 8766905

Claim:
A backlight device which uses a light emitting diode as a light source, the back light device being configured to irradiate a liquid crystal display panel from a rear surface of the liquid crystal display panel, the backlight device having a structure where plural lines are provided on a backlight board with a certain gap, each of the lines being formed by a plurality of the light emitting diodes, the backlight device comprising: a light emitting diode driving part configured to segment an entire screen of the backlight board into plural segmented regions and configured to independently control brightness of the light emitting diodes with a segmented region unit, and a segmented region setting part configured to optionally set a size of the segmented region, wherein the segmented region setting part is configured to set the size of the segmented region so as to change the size of the segmented region based on contents of an image signal; the backlight device further comprises a luminance control part configured to control brightness of the segmented region based on the contents of the image signal, and a luminance detecting part configured to detect luminance distribution of the image signal by using at least one of luminance histogram and average luminance, wherein the luminance control part is configured to control to drive the light emitting diodes with low luminance in the segmented region having low luminance of the image signal, and to drive the light emitting diodes with high luminance in the segmented region having high luminance of the image signal based on luminance information including the luminance distribution detected by the luminance detecting part and information of the segmented region set by the segmented region setting part, and wherein the backlight device further comprises: a plurality of driving circuits provided to each of horizontal direction lines of the light emitting diodes; a plurality of integrating parts, each of the plurality of the integrating parts configured to control two or more driving circuits among the plurality of driving circuits so as to turn on the two or more driving circuits together; a plurality of switches, each of the plurality of the switches configured to connect the each of the plurality of integrating parts and each of the two or more driving circuits; and a control part configured to control a connecting relationship between the each of the integrating parts and the two or more driving circuits via said each of the plurality of the switches, wherein at least one of the driving circuits is connectable to a first integrating part and a second integrating part of the plurality of integrating parts via the switches.