Liquid crystal display device and related operating method

• US 7,978,211 B2
• Filed: 10/17/2007
• Issued: 07/12/2011
• Est. Priority Date: 10/17/2006
• Status: Active Grant

• Current Assignee: InnoLux Corporation
• Original Assignee: InnoLux Corporation
• Inventors: Lin, Po-Yang, Tsai, Chin-Cheng, Chen, Yu-Yeh
• Primary Examiner(s): Eisen; Alexander
• Assistant Examiner(s): MISHLER, ROBIN J
• Application Number:
  US11/975,084
• Publication Number:
  US 20080088650A1
• Time in Patent Office: 1,364 Days
• Field of Search: 345/89, 345/690
• US Class Current: 345/690
• 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 3/2025 the sub-frames having all the same time duration
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

In a liquid crystal display (LCD) device, a plurality of pixels is driven to display a first frame and a second frame in sequence. A gray-scale difference between the first frame and the second frame is detected to determine a driving mode variation between the first frame and the second frame. The number of pixels driven by a dynamic mode and a static mode in the second frame is adjusted according to the driving mode variation. Gray-scale data corresponding to the pixels in the second frame is output.

Claims

1. A method of driving a plurality of pixels of a liquid crystal display (LCD) device when displaying a first frame and a second frame in sequence, the method comprising:

detecting a gray-scale difference between the first frame and the second frame;

determining a driving mode change between the first frame and the second frame based on the detected gray-scale difference;

adjusting a ratio of first pixels, which are driven by a dynamic mode and are included in the plurality of pixels, to second pixels, which are driven by a static mode and are included in the plurality of pixels, in the second frame based on the determined driving mode change; and

outputting gray-scale data based on the adjusted ratio;

wherein outputting the gray-scale data comprises;

(a) counting the number of frames since the first frame is output;

(b) determining a count value based on the counted number of frames;

(c) selecting one of a plurality of driving mode tables based on the count value;

(d) determining whether an additional plurality of pixels included in the plurality of pixels are driven in the static mode or the dynamic mode based on the selected driving mode table;

(e) outputting the gray-scale data corresponding to the additional plurality of pixels in the second frame based on a static gray-scale table if the additional plurality of pixels is driven in the static mode; and

(f) outputting the gray-scale data corresponding to the additional plurality of pixels in the second frame based on a dynamic high gray-scale table and a dynamic low gray-scale table if the additional plurality of pixels is driven in the dynamic mode.

2. The method according to claim 1, wherein the dynamic mode is to drive the first pixels based on a first signal for a first portion of the first frame and a second signal for a second portion of the first frame, the first signal being different from the second signal, and the static mode is to drive a third signal for the first portion of the first frame and a fourth signal for the second portion of the second frame, the third signal being substantially the same as the fourth signal.

3. The method according to claim 1, wherein adjusting the ratio comprises:

increasing a number of the second pixels in the second frame based on the driving mode changing from the dynamic mode of the first frame to the static mode of the second frame.

4. The method according to claim 1, further comprising displaying a third frame to an N^th frame after the second frame, wherein N is a natural number greater than 1, and wherein adjusting the ratio comprises:

gradually increasing the number of the second pixels in the third to (N−

1)^th frames based on the driving mode changing from the dynamic mode of the first frame to the static mode of the second frame, and

driving each of the plurality of pixels in the static mode in the N^th frame.

5. The method according to claim 1, wherein adjusting the ratio comprises:

decreasing a number of the second pixels in the second frame based on the driving mode changing from the static mode of the first frame into the dynamic mode of the second frame.

6. The method according to claim 1, further comprising displaying a third frame to a N^th frame after the second frame, wherein N is a natural number greater than 1, and adjusting the ratio comprises:

gradually decreasing a number of the second pixels in the third to (N−

1)^th frames based on the driving mode changing from the static mode of the first frame to the dynamic mode of the second frame.

7. The method according to claim 1, wherein detecting the gray-scale difference comprises:

obtaining a plurality of gray-scale differences between values of the gray-scale data of the pixels in the first frame and the second frame;

summing the plurality of gray-scale differences to obtain a summed difference; and

comparing the summed difference with a threshold value to generate a driving mode change signal which is used to determine the driving mode change between the first frame and the second frame.

8. A liquid crystal display (LCD) device having a plurality of pixels to display a first frame and a second frame in sequence, the device comprising:

a detecting circuit to detect a gray-scale difference between the first frame and the second frame and output a first signal based on a driving mode variation between the first frame and the second frame;

an adjusting circuit, electrically connected to the detecting circuit, to adjust a number of pixels driven by a dynamic mode and a number of pixels driven by a static mode in the second frame based on the first signal; and

a gray-scale converting circuit, electrically connected to the adjusting circuit, to output gray-scale data corresponding to the plurality of pixels based on the number of pixels driven by the dynamic mode and the number of pixels driven by the static mode in the second frame;

wherein the gray-scale converting circuit comprises;

a timer to count a number of frames after the first frame is output and to output a count value based on the counted number of frames;

a plurality of driving mode tables to each record a different ratio of the pixels driven by the static mode to the pixels driven by the dynamic mode;

a first multiplexer to select the gray-scale data from a static gray-scale table, if an additional plurality of pixels included in the plurality of pixels is driven in the static mode, and from a dynamic high gray-scale table and a dynamic low gray-scale table if the additional plurality of pixels is driven in the dynamic mode; and

a second multiplexer to select a subset of the gray-scale data from the dynamic high gray-scale table and the dynamic low gray-scale table to output from the gray-scale converting circuit.

9. The device according to claim 8, wherein the adjusting circuit is to increase the number of the pixels driven by the static mode in the second frame based on the driving mode being converted from the dynamic mode of the first frame to the static mode of the second frame.

10. The device according to claim 8, wherein the device is to display a third frame to a N^th frame after the second frame, wherein N is a natural number greater than 1, and further wherein the adjusting circuit is to gradually increase the number of the pixels driven by the static mode in the third to N^th frames based on the driving mode being converted from the dynamic mode of the first frame to the static mode of the second frame.

11. The device according to claim 8, wherein the adjusting circuit is to decrease the number of the pixels driven by the static mode in the second frame based on the driving mode being converted from the static mode of the first frame to the dynamic mode of the second frame.

12. The device according to claim 8, wherein the device is to display a third frame to a N^th frame after the second frame, wherein N is a natural number greater than 1, and the adjusting circuit is to gradually decrease the number of the pixels driven by the static mode in the third to (N−

1)^th frames based on the driving mode being converted from the static mode of the first frame to the dynamic mode of the second frame.

13. The device according to claim 8, wherein the detecting circuit is to obtain a plurality of gray-scale differences between values of the gray-scale data of the pixels in the first frame and the second frame, sum the plurality of gray-scale differences to obtain a summed difference, and compare the summed difference with a threshold value to generate the first signal.

14. A liquid crystal display (LCD) device, comprising:

a control circuit to determine a first ratio of pixels to be dynamically driven to pixels to be statically driven during a first frame and a second ratio of pixels to be dynamically driven to pixels to be statically driven during a second frame;

wherein the control circuit comprises;

(a) a detecting circuit to detect a gray-scale difference between the first frame and the second frame to determine a driving mode variation between the first frame and the second frame and to output a driving mode conversion determining signal, (b) an adjusting circuit, to be electrically connected to the detecting circuit, to adjust a ratio of the number of pixels to be driven by a dynamic mode to the number of pixels to be driven by a static mode in the second frame based on the driving mode conversion determining signal; and

(c) a gray-scale converting circuit, to be electrically connected to the adjusting circuit, to output gray-scale data corresponding to the plurality of pixels based on the ratio;

wherein the gray-scale converting circuit comprises (a) a timer to count a number of frames after the first frame is output and to output a count value based on the counted number of frames;

(b) a plurality of driving mode tables to each record a different ratio for the pixels to be driven by the static mode to the pixels to be driven by the dynamic mode;

(c) a first multiplexer to select gray-scale data from a static gray-scale table, if an additional plurality of pixels included in the plurality of pixels is driven in the static mode, and from a dynamic high gray-scale table and from a dynamic low gray-scale table if the additional plurality of pixels is driven in the dynamic mode; and

(d) a second multiplexer to select additional gray-scale data from the selected gray-scale data from the dynamic high gray-scale table and the dynamic low gray-scale table.

15. The device according to claim 14, wherein the adjusting circuit is to increase the number of the pixels driven by the static mode in the second frame based on the driving mode being converted from the dynamic mode of the first frame to the static mode of the second frame.

16. The device according to claim 14, the device to display a third frame to a N^th frame after the second frame, wherein N is a natural number greater than 1, and further wherein the adjusting circuit is to gradually increase the number of the pixels driven by the static mode in the third to (N−

1)^th frames based on the driving mode being converted from the dynamic mode of the first frame to the static mode of the second frame.

17. The device according to claim 14, wherein the adjusting circuit is to decrease the number of the pixels driven by the static mode in the second frame based on the driving mode being converted from the static mode of the first frame to the dynamic mode of the second frame.

18. The device according to claim 14, to device to display a third frame to a N^th frame after the second frame, wherein N is a natural number greater than 1, and the adjusting circuit is to gradually decrease the number of the pixels driven by the static mode in the third to N^th frames based on the driving mode being converted from the static mode of the first frame to the dynamic mode of the second frame.

19. The device according to claim 14, wherein the detecting circuit is to obtain a plurality of gray-scale differences by subtracting values of the gray-scale data of the pixels in the first frame from values of the gray-scale data of the pixels in the second frame, sum the plurality of gray-scale differences to obtain a summed difference, and compare the summed difference with a threshold value to generate a driving mode conversion determining signal and to determine the driving mode variation between the first frame and the second frame.

20. A method of driving pixels of a liquid crystal display (LCD) device when displaying a first frame and a second frame in sequence, the method comprising:

detecting a gray-scale difference between the first frame and the second frame;

determining a driving mode change between the first frame and the second frame based on the gray-scale difference;

driving (a) a first plurality of pixels each with a respective first signal during a first portion of the first frame and a respective second signal during a second portion of the first frame; and

(b) a second plurality of pixels each with a respective third signal during the first portion of the first frame and a respective fourth signal during the second portion of the first frame, wherein each respective first signal is different from each respective second signal and each respective third signal is substantially the same as each respective fourth signal, and the number of the first plurality of pixels in the first frame is different from the number of the first plurality of pixels in the second frame; and

outputting gray-scale data, wherein outputting the gray-scale data comprises;

(a) counting the number of frames since the first frame is output;

(b) determining a count value based on the counted number of frames;

(c) selecting one of a plurality of driving mode tables based on the count value;

(d) determining whether an additional plurality of pixels are driven in the static mode or the dynamic mode based on the selected driving mode table;

(e) outputting the gray-scale data corresponding to the additional plurality of pixels in the second frame based on a static gray-scale table if the additional plurality of pixels is driven in the static mode; and

(f) outputting the gray-scale data corresponding to the additional plurality of pixels in the second frame based on a dynamic high gray-scale table and a dynamic low gray-scale table if the additional plurality of pixels is driven in the dynamic mode.