Backlight controller and liquid crystal display device

• US 8,026,895 B2
• Filed: 04/20/2010
• Issued: 09/27/2011
• Est. Priority Date: 07/07/2009
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Yoshida, Ritsuo
• Primary Examiner(s): Liang; Regina
• Application Number:
  US12/763,915
• Publication Number:
  US 20110007100A1
• Time in Patent Office: 525 Days
• Field of Search: 345 87-100, 345/102, 345/204, 345/76, 345/82, 345/690, 349/61
• US Class Current: 345/102
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G09G 2320/0285 using tables for spatial correction of display data
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

A backlight controller for controlling a backlight unit having a plurality of light sources arranged in a grid layout for illuminating a liquid crystal panel, the backlight controller including: a first calculator configured to calculate an average value and a standard deviation of control values for controlling the light sources, the control values being obtained from a feature quantity of an input image; a second calculator configured to calculate a ratio of the standard deviation to the average value; and a gain controller configured to control a gain to be applied to the control values based on the ratio calculated by the second calculator.

Claims

1. A light source control apparatus for a light emitting module having a plurality of light sources respectively disposed for a plurality of light source areas to illuminate a liquid crystal panel with the light sources, the apparatus for controlling emission of the light sources and comprising:

a first calculator configured to calculate an average value and a standard deviation of control values of the light sources, the control values being obtained from a feature quantity of an input image;

a second calculator configured to calculate a ratio of the standard deviation to the average value that are calculated by the first calculator; and

a gain controller configured to control a gain to be applied to the control values of the light sources based on the ratio calculated by the second calculator.

2. The light source control apparatus of claim 1,

wherein the gain is set by a monotonically increasing function related to the ratio.

3. The light source control apparatus of claim 2,

wherein the monotonically increasing function is for clipping the gain in a range larger than the ratio.

4. A liquid crystal display device comprising:

a liquid crystal panel;

a light emitting module having a plurality of light sources respectively disposed for a plurality of light source areas to illuminate the liquid crystal panel with the light sources; and

a light source control module configured to control emission of the light sources,

wherein the liquid crystal display device further comprises;

a first calculation module configured to calculate an average value and a standard deviation of control values of the light sources, the control values being obtained from a feature quantity of an input image;

a second calculation module configured to calculate a ratio of the standard deviation to the average value that are calculated by the first calculation module; and

a gain controlling module configured to control a gain to be applied to the control values of the light sources based on the ratio calculated by the second calculation module.

5. The liquid crystal display device of claim 4 further comprising:

a correction module configured to correct a video signal for displaying an image on the liquid crystal panel in accordance with the control values of the light sources.