DEVICE AND METHOD FOR CONTROLLING BRIGHTNESS OF ORGANIC LIGHT EMITTING DIODE DISPLAY

• US 20110069098A1
• Filed: 09/21/2010
• Published: 03/24/2011
• Est. Priority Date: 09/22/2009
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Lee, Hyun Jae, Son, Jae-Sung, Kim, Jin-Hyoung
• Granted Patent: US 8,711,084 B2
• Time in Patent Office: Days
• US Class Current: 345/691
• 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 2330/028 Generation of voltages supplied to electrode drivers in a matrix display other than LCD
• CPC Class Codes: G09G 2360/16 Calculation or use of calculated indices related to luminance levels in display data
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336

Abstract

A device and a method for controlling brightness of an OLED display device are disclosed.

The method for controlling brightness of an OLED display device includes the steps of forwarding external brightness control information in a PWM signal or a brightness control data, selecting and normalizing either the PWM signal or the brightness control data into an external brightness adjusting gain, analyzing a received video data to detect a peak brightness value, multiplying the peak brightness value by the external brightness adjusting gain to produce a final peak brightness value, adjusting the R/G/B maximum gamma voltage values according to the final peak brightness value, and generating R/G/B reference gamma voltage sets by using the R/G/B maximum gamma voltage values adjusted thus.

Claims

1. A brightness control device in an OLED display device comprising:

a computer system having either a PWM controller for converting and forwarding external brightness control information into a PWM (Pulse Width Modulation) signal and forwarding the PWM signal or a master for forwarding the brightness control data by using a data communication protocol;

a selector for selecting either the PWM signal from the PWM controller or the brightness control data from the master;

a normalizer for normalizing the PWM signal or the brightness control data from the selector into an external brightness adjusting gain;

a peak brightness value detector for analyzing a video data from the computer system to detect a peak brightness value;

a multiplier for multiplying the peak brightness value by the external brightness adjusting gain to produce a final peak brightness value;

a maximum gamma voltage adjuster for adjusting R/G/B maximum gamma voltage values according to the final peak brightness value; and

a reference gamma voltage generator for generating R/G/B maximum gamma voltage sets by using the R/G/B maximum gamma voltage values from the maximum gamma voltage adjuster.

2. The brightness control device according to claim 1, wherein the normalizer normalizes a preset optical compensation parameter into an optical compensation gain according to an optical characteristic of the picture display unit, and forwards the optical compensation gain to the multiplier, and

the multiplier multiplies the peak brightness value, the external brightness adjusting gain and the optical compensation gain to produce a final peak brightness value.

3. The brightness control device according to claim 2, further comprising:

a PWM extractor for extracting a duty ratio from the PWM signal from the PWM controller; and

a slave for storing the brightness control data from the master to a built-in register according to an address and a command code transmitted with the brightness control data,

wherein the normalizer normalizes the duty ratio from the selector or the brightness control data from the built in register through the selector into the external brightness adjusting gain having a range of 0˜

1.

4. The brightness control device according to claim 3, wherein the built in register stores the optical compensation parameter and the brightness control data, and

the brightness control device further includes an external memory for keeping the data stored at the built in register even if power is turned off.

5. The brightness control device according to claim 1, further comprising a digital to analog converter for converting the R/G/B maximum gamma voltage values from the maximum gamma voltage adjuster into analogous gamma voltages and supplying the analogous gamma voltages to the reference gamma voltage generator.

6. The brightness control device according to claim 5, wherein the digital to analog converter is built-in a power source unit which generating the R/G/B maximum gamma voltages.

7. The brightness control device according to claim 3, wherein the master and the slave uses one of SMBus, I₂C, and SPI communication protocols.

8. The brightness control device according to claim 1, wherein the computer system is used with a liquid crystal display device in common, and

the PWM controller or the master controls a back light unit in the liquid crystal display device.

9. A brightness control device in an OLED display device comprising:

a computer system having either a PWM controller for converting and forwarding external brightness control information into a PWM (Pulse Width Modulation) signal and forwarding the PWM signal or a master for forwarding the brightness control data by using a data communication protocol;

a selector for selecting either the PWM signal from the PWM controller or the brightness control data from the master;

a normalizer for normalizing the PWM signal or the brightness control data from the selector into an external brightness adjusting gain and a preset optical compensation parameter into a optical compensation gain according to an optical characteristic of a picture display unit;

a peak brightness value detector for analyzing a video data from the computer system to detect a peak brightness value;

a first multiplier for multiplying the peak brightness value by the external brightness adjusting gain to produce a final peak brightness value;

a maximum gamma voltage adjuster for adjusting R/G/B maximum gamma voltage values according to the final peak brightness value for the first time;

a second multiplier for multiplying the R/G/B maximum gamma voltage values adjusted thus by the external brightness adjusting gain to adjust the R/G/B maximum gamma voltage values for the second time; and

a reference gamma voltage generator for generating R/G/B maximum gamma voltage sets by using the R/G/B maximum gamma voltage values from the second multiplier.

10. The brightness control device according to claim 9, further comprising:

a PWM extractor for extracting a duty ratio from the PWM signal from the PWM controller; and

a slave for storing the brightness control data from the master to a built-in register according to an address and a command code transmitted with the brightness control data,

wherein the normalizer normalizes the duty ratio from the selector or the brightness control data from the built in register through the selector into the external brightness adjusting gain having a range of 0˜

1.

11. The brightness control device according to claim 10, wherein the built in register stores the optical compensation parameter and the brightness control data, and

the brightness control device further includes an external memory for keeping the data stored at the built in register even if power is turned off.

12. The brightness control device according to claim 9, further comprising a digital to analog converter for converting the R/G/B maximum gamma voltage values from the maximum gamma voltage adjuster into analogous gamma voltages and supplying the analogous gamma voltages to the reference gamma voltage generator.

13. The brightness control device according to claim 12, wherein the digital to analog converter is built-in a power source unit which generating the R/G/B maximum gamma voltages.

14. The brightness control device according to claim 10, wherein the master and the slave uses one of SMBus, I₂C, and SPI communication protocols.

15. The brightness control device according to claim 9, wherein the computer system is used with a liquid crystal display device in common, and

the PWM controller or the master controls a back light unit in the liquid crystal display device.

16. A method for controlling brightness of an OLED display device comprising the steps of:

forwarding external brightness control information as a PWM signal or a brightness control data;

selecting and normalizing either the PWM signal or the brightness control data into an external brightness adjusting gain;

analyzing a received video data to detect a peak brightness value;

multiplying the peak brightness value by the external brightness adjusting gain to produce a final peak brightness value;

adjusting the R/G/B maximum gamma voltage values according to the final peak brightness value; and

generating R/G/B reference gamma voltage sets by using the R/G/B maximum gamma voltage values adjusted thus.

17. The method according to claim 16, further comprising the step of normalizing a preset optical compensation parameter into an optical compensation gain according to an optical characteristic of a picture display unit, and

the peak brightness value, the external brightness adjusting gain, and the optical compensation gain are multiplied to produce the final peak brightness value.

18. The method according to claim 16, further comprising the step of converting the R/G/B maximum gamma voltage values into gamma voltages before the R/G/B maximum gamma voltage sets are generated.

19. A method for controlling brightness of an OLED display device comprising the steps of:

forwarding external brightness control information in a PWM signal or a brightness control data;

selecting and normalizing either the PWM signal or the brightness control data into an external brightness adjusting gain;

normalizing a preset optical compensation parameter into an optical compensation gain according to an optical characteristic of a picture display unit;

analyzing a received video data to detect a peak brightness value;

multiplying the peak brightness value by the optical compensation gain to produce a final peak brightness value;

adjusting the R/G/B maximum gamma voltage values according to the final peak brightness value for the first time;

multiplying the R/G/B maximum gamma voltage values by the external brightness gain to adjust the R/G/B maximum gamma voltage values for the second time; and

generating R/G/B reference gamma voltage sets by using the R/G/B maximum gamma voltage values adjusted for the second time.

20. The method according to claim 19, further comprising the step of converting the R/G/B maximum gamma voltage values into gamma voltages before the R/G/B maximum gamma voltage sets are generated.