Backlight brightness adjustment method and apparatus

• US 10,490,137 B2
• Filed: 03/13/2015
• Issued: 11/26/2019
• Est. Priority Date: 12/31/2014
• Status: Active Grant

• Current Assignee: Skyworth Electronics Incorporated (Skyworth Group Ltd.)
• Original Assignee: Skyworth Electronics Incorporated (Skyworth Group Ltd.)
• Inventors: Fu, Huadong, Huang, Zhe
• Primary Examiner(s): Boddie, William
• Assistant Examiner(s): Gyawali, Bipin
• Application Number:
  US14/906,562
• Publication Number:
  US 20160335957A1
• Time in Patent Office: 1,719 Days
• Field of Search: None
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/064 by time modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0646 Modulation of illumination source brightness and image signal correlated to each other
• CPC Class Codes: G09G 2320/066 for control of contrast
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix
• CPC Class Codes: G09G 3/36 using liquid crystals

Abstract

Disclosed are a backlight brightness adjustment method and apparatus. The backlight brightness adjustment method includes the following steps: dividing a backlight area of a liquid crystal display (LCD) into multiple sub-areas, acquiring maximum pixel brightness M of each sub-area, and acquiring average pixel brightness A according to the maximum pixel brightness M; classifying the brightness into multiple brightness ranges, and separately adjusting duty cycles and drive currents of a backlight source in different brightness ranges according to the average pixel brightness A and the maximum pixel brightness M; determining, according to the maximum pixel brightness M of each sub-area, a brightness range of the sub-area, and acquiring an adjusted duty cycle and drive current that correspond to the brightness range of each sub-area; and correspondingly controlling illumination brightness of each sub-area by using the adjusted duty cycle and drive current. The present invention improves contrast of an LCD.

Claims

1. A backlight brightness adjustment method, wherein the backlight brightness adjustment method comprises the following steps:

dividing a backlight area of a liquid crystal display (LCD) into multiple sub-areas, acquiring maximum pixel brightness M of each sub-area, and acquiring average pixel brightness A according to the maximum pixel brightness M;

classifying the brightness into multiple brightness ranges, wherein, the brightness ranges comprise a first brightness range, a second brightness range, and a third brightness range, brightness in the first brightness range, the second brightness range, and the third brightness range progressively increase;

adjusting the duty cycles of the backlight source in the different brightness ranges according to the average pixel brightness A and the maximum pixel brightness M by using a first algorithm; and

adjusting the drive currents of the backlight source in the different brightness ranges according to the average pixel brightness A, the maximum pixel brightness M, and a maximum drive current of the backlight source by using a second algorithm;

determining, according to the maximum pixel brightness M of each sub-area, a brightness range of the sub-area, and acquiring an adjusted duty cycle and drive current that correspond to the brightness range of each sub-area; and

correspondingly controlling illumination brightness of each sub-area by using the adjusted duty cycle and drive current;

wherein, the operation of adjusting the drive currents of the backlight source in the different brightness ranges according to the average pixel brightness A, the maximum pixel brightness M, and a maximum drive current of the backlight source by using a second algorithm comprises;

in the first brightness range, setting a first drive current I1 of the backlight source to be the maximum drive current I of the backlight source;

in the second brightness range, setting a second drive current I2 of the backlight source to be equal to C1*I+f1(M, A), wherein C1 is a first current adjustment coefficient, 0<

C1<

1, f1(M, A) is a function using the average pixel brightness A and the maximum pixel brightness M as variables, and f1(M, A)>

0; and

in the third brightness range, setting a third drive current I3 of the backlight source to be equal to I+f2(M, A), wherein f2(M, A) is a function using the average pixel brightness A and the maximum pixel brightness M as variables, and f2(M, A)≤

0.

3. The backlight brightness adjustment method according to claim 1, wherein, the operation of adjusting the duty cycles of the backlight source in the different brightness ranges according to the average pixel brightness A and the maximum pixel brightness M by using a first algorithm comprises:

in the first brightness range, setting a first duty cycle P1 of the backlight source to be equal to B1*(M+f(A)), wherein B1 is a first duty cycle adjustment coefficient, and B1>

1, f(A) is a correction function using the average pixel brightness A as a variable.

4. The backlight brightness adjustment method according to claim 3, wherein, the operation of adjusting the duty cycles of the backlight source in the different brightness ranges according to the average pixel brightness A and the maximum pixel brightness M by using a first algorithm further comprises:

in the second brightness range, setting a second duty cycle P2 of the backlight source to be equal to B2*M, wherein B2 is a second duty cycle adjustment coefficient, and 1<

B2<

2; and

in the third brightness range, setting a third duty cycle P3 of the backlight source to be a maximum duty cycle of the backlight source.

5. The backlight brightness adjustment method according to claim 4, wherein, when an input frame is a 100% dark burst frame, the backlight source is turned off, wherein the first duty cycle P1 of the backlight source is equal to 0.

6. The backlight brightness adjustment method according to claim 1, wherein, the operation of dividing a backlight area of an LCD into multiple sub-areas, acquiring maximum pixel brightness M of each sub-area, and acquiring average pixel brightness A according to the maximum pixel brightness M comprises:

dividing the backlight area of the LCD into the multiple sub-areas, detecting pixel brightness of each sub-area, and acquiring maximum pixel brightness M of a light-emitting diode (LED) in each sub-area according to an input frame; and

summing up the maximum pixel brightness M of all the sub-areas and calculating an average value, and using the average value as the average pixel brightness A.

7. The backlight brightness adjustment method according to claim 6, wherein, when the illumination brightness of each sub-area is controlled by using the adjusted duty cycle, the adjusted duty cycle is stored in at least one drive IC register, and a waveform signal corresponding to the duty cycle is output by using the drive IC register to control the illumination brightness of each sub-area.

2. A backlight brightness adjustment apparatus, wherein the apparatus comprises a processor and a memory coupled to the processor, the memory stores programmed instruction units executable by the processor and comprises:

an acquiring module, configured to divide a backlight area of a liquid crystal display (LCD) into multiple sub-areas, acquire maximum pixel brightness M of each sub-area, and acquire average pixel brightness A according to the maximum pixel brightness M;

an adjustment module, configured to classify the brightness into multiple brightness ranges, and separately adjust duty cycles and drive currents of a backlight source in different brightness ranges according to the average pixel brightness A and the maximum pixel brightness M;

a determining module, configured to determine, according to the maximum pixel brightness M of each sub-area, a brightness range of the sub-area, and acquire an adjusted duty cycle and drive current that correspond to the brightness range of each sub-area; and

a control module, configured to correspondingly control illumination brightness of each sub-area by using the adjusted duty cycle and drive current;

wherein the brightness ranges comprise a first brightness range, a second brightness range, and a third brightness range;

brightness in the first brightness range, the second brightness range, and the third brightness range progressively increases; and

the adjustment module comprises;

a duty cycle adjustment unit, configured to adjust the duty cycles of the backlight source in the different brightness ranges according to the average pixel brightness A and the maximum pixel brightness M by using a first algorithm; and

a drive current adjustment unit, configured to adjust the drive currents of the backlight source in the different brightness ranges according to the average pixel brightness A, the maximum pixel brightness M, and a maximum drive current of the backlight source by using a second algorithm;

wherein, the drive current adjustment unit comprises;

a fourth adjustment subunit, configured to;

in the first brightness range, set a first drive current I1 of the backlight source to be the maximum drive current I of the backlight source;

a fifth adjustment subunit, configured to;

in the second brightness range, set a second drive current I2 of the backlight source to be equal to C1*I+f1(M, A), wherein C1 is a first current adjustment coefficient, 0<

C1<

1, f1(M, A) is a function using the average pixel brightness A and the maximum pixel brightness M as variables, and f1(M, A)>

0; and

a sixth adjustment subunit, configured to;

in the third brightness range, set a third drive current I3 of the backlight source to be equal to I+f2(M, A), wherein f2(M, A) is a function using the average pixel brightness A and the maximum pixel brightness M as variables, f2(M, A)≤

0.

8. The backlight brightness adjustment apparatus according to claim 2, wherein, the duty cycle adjustment unit comprises:

a first adjustment subunit, configured to;

in the first brightness range, set a first duty cycle P1 of the backlight source to be equal to B1*(M+f(A)), wherein B1 is a first duty cycle adjustment coefficient, and B1>

1, f(A) is a correction function using the average pixel brightness A as a variable.

9. The backlight brightness adjustment apparatus according to claim 8, wherein, the duty cycle adjustment unit further comprises:

a second adjustment subunit, configured to;

in the second brightness range, seta second duty cycle P2 of the backlight source to be equal to B2*M, wherein B2 is a second duty cycle adjustment coefficient, and 1<

B2<

2; and

a third adjustment subunit, configured to;

in the third brightness range, set a third duty cycle P3 of the backlight source to be a maximum duty cycle of the backlight source.

10. The backlight brightness adjustment apparatus according to claim 9, wherein, the first adjustment subunit is further configured to:

when an input frame is a 100% dark burst frame, turn off the backlight source, wherein the first duty cycle P1 of the backlight source is equal to 0.

11. The backlight brightness adjustment apparatus according to claim 2, wherein, the acquiring module is specifically configured to divide the backlight area of the LCD into the multiple sub-areas, detect pixel brightness of each sub-area, and acquire maximum pixel brightness M of a light-emitting diode (LED) in each sub-area according to an input frame;

and sum up the maximum pixel brightness M of all the sub-areas and calculate an average value, and use the average value as the average pixel brightness A.

12. The backlight brightness adjustment apparatus according to claim 11, wherein, the control module is specifically configured to:

when controlling the illumination brightness of each sub-area by using the adjusted duty cycle, store the adjusted duty cycle in at least one drive IC register, and output, by using the drive IC register, a waveform signal corresponding to the duty cycle to control the illumination brightness of each sub-area.