Method and system for driving an active matrix display device

• US 8,749,465 B2
• Filed: 11/29/2006
• Issued: 06/10/2014
• Est. Priority Date: 11/30/2005
• Status: Active Grant

• Current Assignee: AU Optronics Corporation
• Original Assignee: AU Optronics Corporation
• Inventors: Ho, Yu-Hsi, Hsieh, Yao-Jen, Chang, Wen-Chieh, Su, Fang-Yu
• Primary Examiner(s): HORNER, JONATHAN R
• Application Number:
  US11/605,589
• Publication Number:
  US 20070120801A1
• Time in Patent Office: 2,750 Days
• Field of Search: 345 98- 99, 345/208, 345/210, 345214-215, 345/90, 345 94- 95, 315/169.2
• US Class Current: 345/94
• CPC Class Codes: G09G 2310/0251 Precharge or discharge of pixel before applying new pixel voltage
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• 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 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/3666 with the matrix divided into sections
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A method for driving an active matrix display wherein each image frame is divided into a number of displayed frame portions, each of which is followed by a darker frame portion. The image data in the darker frame portion is removed so as to allow the pixel luminance to diminish. The temporal separation between the displayed frame portion and the following darker frame portion is smaller than a frame time. In a display where the lines are driven repetitively for forming the display image in a plurality of frame times, the image data provided to a pixel, after the luminance in that pixel changes from low to high, is adjusted so that the brightness of the pixel in the preceding frame times appear higher or not lower than that in following frames times.

Claims

1. A method for driving an active matrix display having a plurality of pixels, wherein the pixels are arranged in a plurality of lines for forming a display image and the lines are driven repetitively for forming the display image in a plurality of frame times, the plurality of frame times comprising a first group of frame times and a following second group of frame times, said method comprising:

providing image data to the pixels for producing luminance in the pixels based on the provided data in a first period of a frame time in the first group and in the first period of the frame time in the second group such that the luminance increases with time in the first period in each of the frame times in the first group and in the second group, and

removing at least part of the provided data from the pixels after the first period in each of the frame times at least in the second group so as to reduce the luminance in said pixels in a second period following the first period such that the luminance decreases with time in the second period in each of the frame times in the second group, wherein the sum of the first period and the second period is less than or substantially equal to one frame time, wherein the first group has a first stable state defined by a first maximum value and a first minimum value such that when the first group reaches the first stable state, variation in luminance value in the frame times in the first group is limited between the first maximum value and the first minimum value, and the second group has a second stable state defined by a second maximum value and a non-zero second minimum value such that when the second group reaches the second stable state, maximum luminance value in the frame times in the second group increases to the second maximum value and minimum luminance value in the frame times in the second group increases to the second minimum value, and wherein the first maximum value is lower than the second maximum value and the second minimum value is higher than the first minimum value but lower than the first maximum value, wherein the second group of frame times comprises two or more front frame times followed by two or more subsequent frame times, wherein a sum of the luminance in the first period and the luminance in the second period yields a total luminance, and the total luminance in said pixels in the front frame times is lower than the total luminance in said pixels in the subsequent frame times, said method further comprising;

increasing the image data provided to said pixels in the front frame times such that the maximum luminance value in the front frame times increases to the second maximum value and the minimum luminance value in the front frame times increases to the second minimum value so as to increase the total luminance in each of said two or more front frame times in said pixels.

2. The method of claim 1, wherein the image data is adjusted such that the total luminance in each of said two or more front frame times in said pixels is substantially equal to the total luminance in the subsequent frame times in said pixels.

3. The method of claim 1 further comprising:

adjusting at least the first period in the front frame times so as to increase the total luminance in said pixels in the front frame times.

4. The method of claim 1, wherein the second group of frame times comprises two or more front frame times followed by two or more subsequent frame times, and wherein the luminance in said pixels in the first period is adjustable by a charging time, and wherein a sum of the luminance in the first period and the luminance in the second period yields a total luminance, and the total luminance in said pixels in the front frame times is lower than the total luminance in said pixels in the subsequent frame times, said method further comprising:

adjusting the charging time in the first period in the front frame times so as to increase the total luminance in said pixels in the front frame times.

5. An active matrix display having a plurality of data lines and a plurality of pixels operatively connected to the data lines to receive image data for producing luminance in the pixels, wherein the pixels are arranged in a plurality of lines for forming a display image and the lines are driven repetitively for forming the display image in a plurality of frame times, the plurality of frame times comprising a first group of frame times and a following second group of frame times, said display comprising:

a data source configured to provide the image data; and

a data adjustment circuit configured to adjust the image data so that the image data is provided in the first period of the frame time at least in the second group such that the luminance increases with time in the first period, and at least part of the provided data is removed from the pixels after the first period in each of the frame times at least in the second group so as to reduce the luminance in said pixels in a second period following the first period such that the luminance decreases with time in the second period in each of the frame times in the second group, wherein the sum of the first period and the second period is less than or substantially equal to one frame time, wherein the first group has a first stable state defined by a first maximum value and a first minimum value such that when the first group reaches the first stable state, variation in luminance value in the frame times in the first group is limited between the first maximum value and the first minimum value, and the second group has a second stable state defined by a second maximum value and a nonzero second minimum value such that when the second group reaches the second stable state, maximum luminance value in the frame times in the second group increases to the second maximum value and minimum luminance value in the frame times in the second group increases to the second minimum value, and wherein the first maximum value is lower than the second maximum value and the second minimum value is higher than the first minimum value but lower than the first maximum value, wherein the second group of frame times comprises two or more front frame times followed by two or more subsequent frame times, and wherein a sum of the luminance in the first period and the luminance in the second period yields a total luminance, and the total luminance in said pixels in the front frame times is lower than the total luminance in said pixels in the subsequent frame times wherein the data adjustment circuit is adapted to increase the image data provided to said pixels in the front frame times such that the maximum luminance value in the front frame times increases to the second maximum value and the minimum luminance value in the front frame times increases to the second minimum value so as to increase the total luminance in each of said two or more front frame times in said pixels and the image data is increased such that the total luminance in each of said two or more front frame times in said pixels is substantially equal to the total luminance in the subsequence frame times in said pixels.

6. The display of claim 5, wherein the data adjustment circuit is adapted to further adjust at least the first period in the front frame times so as to increase the total luminance in said pixels in the front frame times.

7. The display of claim 5, wherein the second group of frame times comprises two or more front frame times followed by two or more subsequent frame times, and wherein the luminance in said pixels in the first period is adjustable by a charging time, and wherein a sum of the luminance in the first period and the luminance in the second period yields a total luminance, and the total luminance in said pixels in the front frame times is lower than the total luminance in said pixels in the subsequent frame tithes, wherein the data adjustment circuit is adapted to further adjust the charging time in the first period in the front frame times so as to increase the total luminance in said pixels in the front frame times.

8. The display of claim 5, comprising a liquid crystal display.

9. A data adjustment module for use in an active matrix display having a plurality of data lines and a plurality of pixels operatively connected to the data lines to receive image data for producing luminance in the pixels, wherein the pixels are arranged in a plurality of lines for forming display images in a plurality of frames in a plurality of frame times, the plurality of frame times comprising a first group of frame times and a following second group of frame times, said data adjustment module comprising:

a timing generator, adapted to compare the image data in a current frame with the input data in one or more previous frames, for providing a signal based on said comparing; and

a timing controller for controlling the image data, based on the signal, such that the image data is provided to the pixels in a first period of a frame dine in the first group and in the first period of the frame time in the second group such that the luminance increases with time in the first period in each of the frame times in the first group and in the second group, and at least part of the image data is removed from the pixels in a second period of frame time following the first period in order to reduce the luminance in said pixels in the second period such that the luminance decreases with time in the second period in each of the frame times at least in the second group, wherein the sum of the first period and the second period is less than or substantially equal to one frame time, wherein the first group has a first stable state defined by a first maximum value and a first minimum value such that when the first group reaches the first stable state, variation in luminance value in the frame times in the first group is limited between the first maximum value and the first minimum value, and the second group has a second stable state defined by a second maximum value and a non-zero second minimum value such that when the second group reaches the second stable state, maximum luminance value in the frame times in the second group increases to the second maximum value and minimum luminance value in the frame times in the second group increases to the second minimum value, and wherein the first maximum value is lower than the second maximum value and the second minimum value is higher than the first minimum value but lower than the first maximum value, wherein the second group of frame times comprises two or more front frame times followed by two or more subsequent frame times, and wherein a sum of the luminance in the first period and the luminance in the second period yields a total luminance, and the total luminance in said pixels in the front frame times is lower than the total luminance in said pixels in the subsequent frame times, wherein the data adjustment module is adapted to increase the image data provided to said pixels in the front frame times so as to increase the total luminance in each of said two or more front frame times in said pixels, wherein the image data is increased such that the total luminance in each of said two or more front frame times in said pixels is substantially equal to the total luminance in the subsequent frame times in said pixels.