LIQUID CRYSTAL DISPLAY AND LIQUID CRYSTAL DRIVE CIRCUIT

• US 20080309601A1
• Filed: 06/11/2008
• Published: 12/18/2008
• Est. Priority Date: 06/12/2007
• Status: Abandoned Application

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: FURUKOSHI, Yasutake
• Application Number:
  US12/137,179
• Publication Number:
  US 20080309601A1
• Time in Patent Office: Days
• US Class Current: 345/89
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3677 suitable for active matrices only

Abstract

A liquid crystal display includes pixels, gate lines, source lines and a drive means. Each of the pixels includes a TFT element, a liquid crystal element and an auxiliary capacitive device. One end of the liquid crystal device is connected to one end of the TFT device, and the auxiliary capacitive device is provided to be connected between the one end of the TFT device and an adjacent gate line. In a normal drive mode, the drive means drives each pixel on the basis of an image data acquired through correction which allows image luminance level of the current unit frame to be lowered by a predetermined amount. In an overdrive mode, the drive means drives each pixel on the basis of an image data which brings a larger amount of change of a voltage across the liquid crystal device between the previous unit frame and the current unit frame.

Claims

1. A liquid crystal display comprising:

a plurality of pixels disposed in a matrix form, each of the pixel including a TFT element, a liquid crystal element functioning as a main capacitive element, and an auxiliary capacitive element,

a gate line selecting a pixel to be driven in a line-sequential manner so that the TFT element in the selected pixel is selectively changed to on-state through application of on-voltage, and selectively changed to off-state through application of off-voltages,

a source line supplying an image data to the pixel to be driven through the TFT element, and

a drive section driving the pixels for display in a line-sequential manner,

wherein one end of the liquid crystal element is connected to one end of the TFT element, one end of the auxiliary capacitive element is connected to the one end of the TFT element while other end of the auxiliary capacitive element is connected to an adjacent gate line, and the drive means refers to image data both of a current unit frame and a previous unit frame, so that,

in a normal drive mode, the drive means drives the pixels one by one on the basis of an image data obtained through correction in which image luminance level of the current unit frame is lowered by a predetermined amount, and

in an overdrive mode, the drive means drives the pixels one by one on the basis of an image data which allows a larger change of a voltage across the liquid crystal element between the previous unit frame and the current unit frame.

2. The liquid crystal display according to claim 1, wherein the drive means includes:

a determination means for referring to the image data both of the current unit frame and the previous unit frame, and determining, pixel by pixel, whether the normal drive mode or the overdrive mode is to be performed for the current frame; and

a correction means for correcting the image data of the current unit frame, pixel by pixel, on the basis of a determination result from the determination means.

3. The liquid crystal display according to claim 2, wherein the determination means determines to perform the overdrive mode for a pixel in which luminance level difference between the current unit frame and the previous unit frame is equal to or larger than a threshold value, while determines to perform the normal drive mode for a pixel in which the luminance level difference is smaller than the threshold value.

4. The liquid crystal display according to claim 3, wherein, in the overdrive mode, the correction means corrects the image data of the current unit frame for the pixel in which the luminance level difference is equal to or larger than the threshold value so that an amount of change of voltage across a liquid crystal element increases as the luminance level difference increases.

5. The liquid crystal display according to claim 1, wherein the drive means performs the overdrive mode by using the image data of the current unit frame without changing the luminance level thereof, for the pixel to be changed from a black display state to a white display state.

6. The liquid crystal display according to claim 1, wherein the drive means performs the overdrive mode by using the image data corrected in such a manner that the luminance level of the current unit frame is lowered by an amount which is larger than the predetermined amount in the normal drive mode.

7. The liquid crystal display according to claim 1, wherein the image luminance level based on corrected image data after stabilization of the voltage across the liquid crystal element in the normal drive mode is equivalent to a image luminance level based on non-corrected image data just after application of a voltage across the liquid crystal element.

8. The liquid crystal display according to claim 1, wherein two gate lines are provided for a row of the plurality of pixels along the gate line, each of the two gate lines connected to a gate of the TFT element in every other pixel in the row, and

the drive means drives the pixels in such a manner that a couple of voltages with different polarities are applied across the liquid crystal elements in two pixels adjacent to each other along the gate lines, respectively, as well as in two pixels adjacent to each other along the source line, respectively.

9. A liquid crystal drive circuit applied to a liquid crystal display, the liquid crystal display comprising:

a plurality of pixels disposed in a matrix form, each of the pixel including a TFT element, a liquid crystal element functioning as a main capacitive element, and an auxiliary capacitive element,

a gate line selecting a pixel to be driven in a line-sequential manner so that the TFT element in the selected pixel is selectively changed to on-state through application of on-voltage, and selectively changed to off-state through application of off-voltages, and

a source line supplying an image data to the pixel to be driven through the TFT element, the liquid crystal drive circuit driving the pixels for display in a line-sequential manner,

wherein one end of the liquid crystal element is connected to one end of the TFT element, one end of the auxiliary capacitive element is connected to the one end of the TFT element while other end of the auxiliary capacitive element is connected to an adjacent gate line, and the drive means refers to image data both of a current unit frame and a previous unit frame, so that;

in a normal drive mode, the drive means drives the pixels one by one on the basis of an image data obtained through correction in which image luminance level of the current unit frame is lowered by a predetermined amount, and

in an overdrive mode, the drive means drives the pixels one by one on the basis of an image data which allows a larger change of a voltage across the liquid crystal element between the previous unit frame and the current unit frame.