Method of dimming a light source and display apparatus for performing the method

• US 9,241,379 B2
• Filed: 04/29/2010
• Issued: 01/19/2016
• Est. Priority Date: 06/08/2009
• Status: Expired due to Fees

• Current Assignee: Samsung Display Company Limited (Samsung Group)
• Original Assignee: Samsung Display Company Limited (Samsung Group)
• Inventors: Shin, Ho-Sik, Park, Se-Ki, Kang, Seok-Won, Song, Hee-Kwang, Kim, Gi-Cherl
• Primary Examiner(s): Kirkpatrick, John
• Application Number:
  US12/769,852
• Publication Number:
  US 20100309194A1
• Time in Patent Office: 2,091 Days
• Field of Search: 345/102
• US Class Current: 1/1
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0238 Improving the black level
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: H05B 45/10 Controlling the intensity of the light
• CPC Class Codes: H05B 45/38 using boost topology

Abstract

A method of dimming a light source module including a light guide plate, a first light emitting module including first to k-th light source blocks, wherein the first light emitting module is disposed on a first edge of the light guide plate, and a second light emitting module including first to m-th light source blocks, the second light emitting module being disposed on a second edge of the light guide plate, the second edge disposed opposite the first, the method including; generating a first group of driving signals and a second group of driving signals based on an image signal and driving the first to k-th light source blocks using the first group of the driving signals during a first period in a reference period and driving the first to m-th light source blocks using the second group of driving signals during a second period in the reference period.

Claims

1. A method of dimming a light source module, comprising:

generating a first group of first to k-th driving signals and a second group of first to m-th driving signals, based on an image signal;

driving first to k-th light source blocks of a first light emitting module using the first group of first to k-th driving signals during a first period of a reference period, and driving first to m-th light source blocks of a second light emitting module using the second group of first to m-th driving signals during a second period of the reference period; and

determining the duration of the first period and the duration of the second period using a luminance ratio between a first partial image displayed on a portion of a display panel adjacent to the first light emitting module and a second partial image, which is different from the first partial image, displayed on a portion of the display panel adjacent to the second light emitting module,

wherein the light source module comprises a light guide plate, the first light emitting module disposed at a first edge of the light guide plate, and the second light emitting module disposed at a second edge of the light guide plate being disposed substantially opposite to the first edge of the light guide plate,

wherein k and m are natural numbers, and

wherein a first selecting signal turns on a first switching element connected to the first light emitting module at the start point of the first period which is the start point of the reference period, and turns off the first switching element before the end point of the first period, and

a second selecting signal turns on a second switching element connected to the second light emitting module at the start point of the second period which is the end point of the first period and turns off the second switching element before the end point of the second period which is the end point of the reference period.

2. The method of claim 1, further comprising driving a third light emitting module and a fourth light emitting module during the reference period,

wherein the light source module further comprises the third light emitting module disposed at a third edge of the light guide plate being adjacent to the first edge of the light guide plate and the fourth light emitting module disposed at a fourth edge of the light guide plate being substantially opposite to the third edge of the light guide plate.

3. The method of claim 1, further comprising boosting luminance of a light source block having a short driving period among light source blocks corresponding to a predetermined image when the predetermined image having a uniform grayscale is disposed in a boundary area between the first partial image and the second partial image.

4. The method of claim 1, further comprising determining duty ratios of the first group of first to k-th driving signals and the second group of first to m-th driving signals based on the image signal, wherein k is equal to m,

wherein the duty ratios of the first group of first to k-th driving signals are substantially the same as the duty ratios of the second group of first to m-th driving signals, respectively.

5. The method of claim 4, further comprising compensating the first period and the second period via a low pass filtering process based on a first period and a second period of a previous frame.

6. The method of claim 4, further comprising compensating each of the duty ratios of the first group of first to k-th driving signals and the duty ratios of the second group of first to m-th driving signals via a low pass filtering process based on a duty ratio of a previous frame;

and

compensating each of the duty ratios of the first group of first to k-th driving signals and the duty ratios of the second group of first to m-th driving signals via a low pass filtering process based on a duty ratio of an adjacent light source block.

7. The method of claim 1, wherein the first period and the second period are substantially the same length as each other.

8. The method of claim 7, further comprising determining a first group of duty ratios respectively corresponding to the first group of first to k-th driving signals and a second group of duty ratios respectively corresponding to the second group of first to m-th driving signals, based on the image signal.

9. The method of claim 8, further comprising boosting luminance of a light source block having a lesser duty ratio among light source blocks corresponding to a predetermined image when the predetermined image having a substantially uniform grayscale is disposed on a portion of a display panel corresponding to adjacent light source blocks.

10. The method of claim 8, further comprising:

compensating each of the first group of duty ratios and the second group of duty ratios, based on a duty ratio of a previous frame via a low pass filtering process; and

compensating each of the first group of duty ratios and the second group of duty ratios, based on a duty ratio of an adjacent light source block via the low pass filtering process.

11. A display apparatus comprising:

a display panel;

a light source module comprising a first light emitting module including first to k-th light source blocks and disposed at a first edge of the display panel, and a second light emitting module including first to m-th light source blocks and disposed at a second edge of the display panel, the second edge being disposed substantially opposite to the first edge;

a first switching element connected to the first light emitting module;

a second switching element connected to the second light emitting module; and

a light source driver which generates a first group of first to k-th driving signals to drive the first to k-th light source blocks of the first light emitting module during a first period of a reference period, and which generates a second group of first to m-th driving signals to drive the first to m-th light source blocks of the second light emitting module during a second period of the reference period, wherein k and m are natural numbers,

wherein the light source driver comprises a cycle decision part which determines the duration of the first period and the duration of the second period using a luminance ratio between a first partial image displayed on a portion of the display panel adjacent to the first light emitting module and a second partial image, which is different from the first partial image, displayed on a portion of the display panel adjacent to the second light emitting module, and

wherein a first selecting signal turns on the first switching element at the start point of the first period which is the start point of the reference period, and turns off the first switching element before the end point of the first period, and

a second selecting signal turns on the second switching element at the start point of the second period which is the end point of the first period and turns off the second switching element before the end point of the second period which is the end point of the reference period.

12. The display apparatus of claim 11, wherein the light source module further comprises a third light emitting module disposed at a third edge of the display panel adjacent to the first edge and a fourth light emitting module disposed at a fourth edge of the display panel opposite to the third edge, and

the light source driver drives the third light emitting module and the fourth light emitting module during the reference period.

13. The display apparatus of claim 11, wherein the light source driver further comprises:

a dimming level decision part which determines first to k-th duty ratios using first to k-th image blocks displayed on the display panel; and

a signal generator which generates the first group of first to k-th driving signals and the second group of first to m-th driving signals using the first to k-th duty ratios, the first period and the second period.

14. The display apparatus of claim 13, wherein the light source driver further comprises:

a time low pass filter which compensates the first period and the second period based on a first period and a second period of a previous frame via a low pass filtering process, and which compensates each of the first to k-th duty ratios based on a duty ratio of the previous frame via the low pass filtering process; and

a spatial low pass filter which compensates each of the first to k-th duty ratios based on a duty ratio of an adjacent light source block via the low pass filtering process.

15. The display apparatus of claim 13, wherein the light source driver boosts luminance of a light source block having a short driving period among light source blocks corresponding to a predetermined image when the predetermined image having a uniform grayscale is disposed in a boundary area between the first partial image and the second partial image.

16. The display apparatus of claim 11, wherein the first period and the second period are substantially the same length.

17. The display apparatus of claim 16, wherein the light source driver comprises:

a dimming level decision part which determines a first group of duty ratios corresponding to the first to k-th light source blocks of the first light emitting module and a second group of duty ratios corresponding to the first to m-th light source blocks of the second light emitting module, based on the image signal; and

a signal generator which generates the first group of first to k-th driving signals based on the first group of duty ratios, and the second group of first to m-th driving signals based on the second group of duty ratios.

18. The display apparatus of claim 17, wherein the light source driver further comprises a boosting decision part which boosts luminance of a light source block having a small duty ratio among the light source blocks corresponding to a predetermined image when the predetermined image having a uniform grayscale is disposed on adjacent light emitting blocks.

19. The display apparatus of claim 17, wherein the light source driver further comprises:

a time low pass filter which compensates each of the first group of duty ratios and the second group of duty ratios based on the duty ratio of a previous frame via a low pass filtering process; and

a spatial low pass filter which compensates each of the first group of duty ratios and the second group of duty ratios based on a duty ratio of an adjacent light source block via the low pass filtering process.