Liquid crystal display device using OCB cell and driving method thereof
AssigneeMatsushita Electric Industrial Co., Ltd.
InventorsYoshihito Ohta, Katsuyuki Arimoto, Takahiro Kobayashi, Taro Funamoto
Life of this patent
Estimating the term…
Abstract
A liquid crystal display device capable of suppressing the occurrence of a back transition in OCB cells and displaying excellent images as well as a driving method thereof are provided. One frame period has a first period P1 for writing a signal for initializing the state of a liquid crystal in pixel cells and a second period for writing pixel data in correspondence with an image signal in pixel cells, and a voltage level to be applied to each pixel cell is set in the first period such that each pixel cell retains a voltage Vsup higher than that in the second period.
Claims3
A method for driving a liquid crystal display device having a liquid crystal panel, the liquid crystal panel comprising a plurality of source lines to which pixel data are supplied, a plurality of gate lines to which scanning signals are supplied, pixel cells positioned in matrix form in correspondence with intersecting points of the source lines and the gate lines, a source driver that drives the source lines based on an input image signal, a gate driver that drives the gate lines, and a back light, the pixel cells being applied with a signal for initializing a state of a liquid crystal therein as well as pixel data in correspondence with the image signal in the pixel cells,
- wherein a first period for writing the signal for initializing a state of the pixel cells and a second period for writing the pixel data are provided in one frame period,
- a length of the first period is set variably for each frame,
- a voltage level to be applied to each pixel cell in the first period is set such that each pixel cells retains a voltage Vsup higher than a voltage level to be applied to each pixel cell in the second period, and
- the length of the first period is controlled by a result of calculating an average luminance level by an image signal input in a predetermined number of preceding frames and an average luminance level by an image signal to be input in a current frame.
A method for driving a liquid crystal display device having a liquid crystal panel, the liquid crystal panel comprising a plurality of source lines to which pixel data are supplied, a plurality of gate lines to which scanning signals are supplied, pixel cells positioned in matrix form in correspondence with intersecting points of the source lines and the gate lines, a source driver that drives the source lines based on an input image signal, a gate driver that drives the gate lines, and a back light, the pixel cells being applied with a signal for initializing a state of a liquid crystal therein as well as pixel data in correspondence with the image signal in the pixel cells,
- wherein a first period for writing the signal for initializing a state of the pixel cells and a second period for writing the pixel data are provided in one frame period,
- a length of the first period is set variably for each frame,
- a voltage level to be applied to each pixel cell in the first period is set such that each pixel cells retains a voltage Vsup higher than a voltage level to be applied to each pixel cell in the second period, and
- it is detected whether an input image signal is a moving image or a static image, and as a result of detection, the first period is set longer than a predetermined length when it is judged that the input image signal is a moving image, and the first period is set shorter than a predetermined length when it is judged that the input image signal is a static image.
Dependencies are inferred from the claim text.