Image display device with gain calculator and overdrive unit

• US 8,310,438 B2
• Filed: 01/07/2010
• Issued: 11/13/2012
• Est. Priority Date: 02/24/2009
• Status: Active Grant

• Current Assignee: JVC Kenwood Corporation
• Original Assignee: JVC Kenwood Corporation
• Inventors: Shishido, Tomoyuki, Aiba, Hideki
• Primary Examiner(s): Nguyen, Chanh
• Assistant Examiner(s): WALTHALL, ALLISON N
• Application Number:
  US12/654,887
• Publication Number:
  US 20100214330A1
• Time in Patent Office: 1,041 Days
• Field of Search: 345/89, 345/102, 345/103, 345/87, 345/99, 345/606, 345/643
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/106 Determination of movement vectors or equivalent parameters within the image
• CPC Class Codes: G09G 2340/0435 Change or adaptation of the frame rate of the video stream
• CPC Class Codes: G09G 2340/10 Mixing of images, i.e. displayed pixel being the result of an operation, e.g. adding, on the corresponding input pixels
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
• CPC Class Codes: G09G 5/00 Control arrangements or circuits for visual indicators common to cathode-ray tube indicators and other visual indicators image data processing or generation, in general G06T

Abstract

An image display device includes a gain calculator, a multiplier and an overdrive unit. The gain calculator calculates a ratio “Gmax0/Gmax1” as gain, with respect to each segmented region of liquid crystal panel. The symbol “Gmax1” represents a maximum gradation in one frame period of an image signal to be supplied to each segmented region. The symbol “Gmax0” represents a maximum gradation to be determined depending on the number of bits in the image signal. The multiplier multiplies an image signal subjected to frame frequency conversion in a frame frequency conversion unit by the gain to generate an image signal subjected to the area control processing, with respect to each segmented region. The overdrive unit emphasizes the image signal subjected to the area control processing, using an image signal generated by delaying the image signal subjected to the area control processing for one frame period.

Claims

1. An image display device comprising:

a liquid crystal panel that displays an image thereon based on an image signal;

a backlight device that is mounted on a back side of the liquid crystal panel and segmented into plural regions, and has light sources for emitting light to the liquid crystal panel which are arranged on each region;

a delay unit that delays a first image signal with a first frame frequency for one frame period to generate a second image signal;

an interpolation image signal generating unit that generates one or plural interpolation image signals to be inserted between adjacent frames in the first image signal, using the first image signal and the second image signal;

a gain calculator that calculates a gain based on a ratio of a maximum gradation in one frame period of the first image signal and a maximum gradation to be determined depending on the number of bits in an image signal, with respect to each region of the liquid crystal panel corresponding to the each region of the backlight device;

a first multiplier that multiplies the first image signal by the gain to generate the multiplied first image signal;

a second multiplier that multiplies the second image signal by the gain to generate the multiplied second image signal;

at least one multiplier that multiplies the one or plural interpolation image signals by the gain to generate the multiplied one or plural interpolation image signals;

an overdrive unit that carries out processing for emphasizing the multiplied first image signal and the multiplied one or plural interpolation image signals in a time axis direction, using the multiplied one or plural interpolation image signals and the multiplied second image signal adjacent to the multiplied first image signal and the multiplied one or plural interpolation image signals on time series, to generate a first image signal and one or plural interpolation image signal subjected to the emphasis processing; and

a frame frequency conversion unit that inserts the one or plural interpolation image signals having been subjected to the emphasis processing between the adjacent frames in the first image signal having been subjected to the emphasis processing to generate an image signal with a second frame frequency higher than the first frame frequency.

2. The image display device according to claim 1, further comprising:

a control unit that controls the light sources arranged on each region of the backlight device such that the light sources emit light at a light amount depending on an inverse of the gain calculated by the gain calculator with respect to each region of the liquid crystal panel corresponding to the each region of the back light device.