Apparatus and method to improve quality of moving image displayed on liquid crystal display device

• US 7,133,015 B1
• Filed: 08/30/2000
• Issued: 11/07/2006
• Est. Priority Date: 10/13/1999
• Status: Expired due to Term

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Yoshida, Hidefumi, Yamaguchi, Hisashi, Ohashi, Makoto
• Primary Examiner(s): Mengistu, Amare
• Application Number:
  US09/651,288
• Time in Patent Office: 2,260 Days
• Field of Search: 345/87, 345/100, 345/102, 345/98, 345/99, 345/103, 345/84, 345/89
• US Class Current: 345/99
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2310/04 Partial updating of the display screen
• CPC Class Codes: G09G 2310/062 Waveforms for resetting a plurality of scan lines at a time
• CPC Class Codes: G09G 2310/063 Waveforms for resetting the whole screen at once
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• 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 2330/021 Power management, e.g. power saving
• 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 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3666 with the matrix divided into sections

Abstract

A liquid crystal display device comprises a panel having pixel electrodes arranged at intersections of a plurality of signal lines via switching elements for transmitting display data and a plurality of scanning lines for transmitting control signals, and a control circuit for controlling the panel. The liquid crystal panel is divided into first pixel regions and second pixel regions adjacent to the first pixel regions. The control circuit carries out impulse driving in which the control signals transmitted to each of the scanning lines are activated two times in one frame period for displaying an image. The control circuit writes the display data in either one of the pixel regions and writes reset data in the other pixel regions when the control signals are activated once of the two times. By writing the reset data in the pixel regions, the display data written in an immediately preceding frame are reset. In consecutive frames, the display data written in the pixel regions are always reset in one frame period. Therefore, blurring in a moving image can be alleviated. Since writing the display data and the reset data is carried out separately in the first pixel regions and in the second pixel regions, flicker is prevented from occurring in a display screen.

Claims

1. A liquid crystal display device, comprising:

a liquid crystal panel in which a plurality of signal lines for transmitting display pixel data and a plurality of scanning lines for transmitting control signals are laid out vertically and horizontally, and pixel electrodes are arranged at intersections of the signal lines and the scanning lines via switching elements,

wherein the device has a hold control function in which an image to be displayed is output in one entire frame period, and an impulse control function in which an image to be displayed is output in a predetermined period within the one frame period and is not output during a remaining period within the one frame period,

wherein said hold control is carried out when said display image is shown with all of the pixel electrodes and is a still image,

wherein said impulse control is carried out when said display image is shown with all of the pixel electrodes and is a moving image,

wherein motion compensation is carried out by using DCT (Discrete Cosine Transform), and

wherein said display image is judged to be said moving image and said hold control is switched to said impulse control when compressed image information includes vector information indicating image motion.