Driving Apparatus of Backlight Module and Driving Method Thereof

• US 20120092386A1
• Filed: 04/25/2011
• Published: 04/19/2012
• Est. Priority Date: 10/15/2010
• Status: Active Grant

• Current Assignee: InnoLux Corporation
• Original Assignee: InnoLux Corporation
• Inventors: Wu, Tung-Ying
• Granted Patent: US 8,605,031 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• 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 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A driving apparatus of a backlight module and a driving method thereof are provided. The driving method includes following steps. An image signal is received. A first grayscale mean of a current frame and a second grayscale mean of a previous frame are calculated according to the image signal. A first difference between the first grayscale mean and the second grayscale mean is calculated. A first duty corresponding to the current frame and a second duty corresponding to the previous frame are calculated according to the image signal. When the first difference is smaller than or equal to a backlight flicker threshold, a backlight control signal is generated according to the second duty and a first regulation value. When the first difference is greater than the backlight flicker threshold, the backlight control signal is generated according to the second duty and a second regulation value.

Claims

1. A driving apparatus of a backlight module, comprising:

a grayscale mean calculating unit, for receiving an image signal and calculating a first grayscale mean of a current frame and a second grayscale mean of a previous frame;

an error calculating unit, coupled to the grayscale mean calculating unit, for receiving the first grayscale mean and the second grayscale mean and calculating a first difference between the first grayscale mean and the second grayscale mean;

a backlight duty calculating unit, for receiving the image signal and calculating a first duty corresponding to the current frame and a second duty corresponding to the previous frame; and

a backlight control signal generating unit, coupled to the error calculating unit and the backlight duty calculating unit, for receiving the first duty, the second duty, and the first difference, wherein when the first difference is smaller than or equal to a backlight flicker threshold, the backlight control signal generating unit generates a backlight control signal according to the second duty and a first regulation value, when the first difference is greater than the backlight flicker threshold, the backlight control signal generating unit generates the backlight control signal according to the second duty and a second regulation value, and the first regulation value is different from the second regulation value.

2. The driving apparatus according to claim 1, wherein the first regulation value is a product of a first reference value and a ratio of a duty distribution value to a duty error value, wherein the first reference value is smaller than 1 and greater than 0, the duty distribution value is a difference between a maximum duty and a minimum duty, and the duty error value is a difference between the first duty and the second duty.

3. The driving apparatus according to claim 2, wherein the second regulation value is a product of a second reference value and a ratio of the duty distribution value to the duty error value, wherein the second reference value is greater than or equal to 1.

4. The driving apparatus according to claim 3, wherein the first reference value and the second reference value are reciprocal to each other.

5. The driving apparatus according to claim 1, wherein when the first difference is smaller than or equal to the backlight flicker threshold and the first duty is greater than or equal to the second duty, a duty of the backlight control signal is equal to the second duty plus the first regulation value.

6. The driving apparatus according to claim 1, wherein when the first difference is smaller than or equal to the backlight flicker threshold and the first duty is smaller than the second duty, a duty of the backlight control signal is equal to the second duty minus the first regulation value.

7. The driving apparatus according to claim 1, wherein when the first difference is greater than the backlight flicker threshold and the first duty is greater than or equal to the second duty, a duty of the backlight control signal is equal to the second duty plus the second regulation value.

8. The driving apparatus according to claim 1, wherein when the first difference is greater than the backlight flicker threshold and the first duty is smaller than the second duty, a duty of the backlight control signal is equal to the second duty minus the second regulation value.

9. A driving method of a backlight module, comprising:

receiving an image signal;

calculating a first grayscale mean of a current frame and a second grayscale mean of a previous frame according to the image signal;

calculating a first difference between the first grayscale mean and the second grayscale mean;

calculating a first duty corresponding to the current frame and a second duty corresponding to the previous frame according to the image signal;

when the first difference is smaller than or equal to a backlight flicker threshold, generating a backlight control signal according to the second duty and a first regulation value; and

when the first difference is greater than the backlight flicker threshold, generating the backlight control signal according to the second duty and a second regulation value, wherein the second regulation value is different from the first regulation value.

10. The driving method according to claim 9, wherein the first regulation value is a product of a first reference value and a ratio of a duty distribution value to a duty error value, wherein the first reference value is smaller than 1 and greater than 0, the duty distribution value is a difference between a maximum duty and a minimum duty, and the duty error value is a difference between the first duty and the second duty.

11. The driving method according to claim 10, wherein the second regulation value is a product of a second reference value and a ratio of the duty distribution value to the duty error value, wherein the second reference value is greater than or equal to 1.

12. The driving method according to claim 11, wherein the first reference value and the second reference value are reciprocal to each other.

13. The driving method according to claim 9, wherein the step of generating the backlight control signal according to the second duty and the first regulation value comprises:

wherein when the first duty is greater than or equal to the second duty, a duty of the backlight control signal is equal to the second duty plus the first regulation value; and

when the first duty is smaller than the second duty, the duty of the backlight control signal is equal to the second duty minus the first regulation value.

14. The driving method according to claim 9, wherein the step of generating the backlight control signal according to the second duty and the second regulation value comprises:

wherein when the first duty is greater than or equal to the second duty, a duty of the backlight control signal is equal to the second duty plus the second regulation value; and

when the first duty is smaller than the second duty, the duty of the backlight control signal is equal to the second duty minus the second regulation value.