Backlight Driving Current Control for Brightness Convergence
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Solution Overview
Problem
In electronic devices using active matrix backlight units, there is an issue where data held when a gate is turned off influences the brightness, leading to insufficient time for reaching the desired brightness value, affecting the light output.
Innovation Solution
An electronic device with a processor that identifies the intensity of a driving current based on grayscale values and applies a second control value greater than the first to the driving part, allowing for more precise control of the backlight unit's brightness by using a combination of PWM and PAM methods, ensuring the backlight unit reaches the target brightness efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If data is held when a gate is turned off in an active matrix backlight unit, then the source data is maintained until the next gate signal, but the previous data exerts influence on the current LED brightness and the desired brightness value cannot be reached
Solution Approach 1:
The patent segments the control approach by introducing separate first and second control values for different time periods within the same grayscale period. The first control value is applied during the first time period when the gate is off, and the second control value is applied during the second time period when the gate is on, allowing independent optimization of control for each phase to eliminate the influence of held data on current brightness
Solution Approach 2:
The patent applies preliminary action by providing the first control value during the first time period before the gate is turned on. This preliminary control adjusts the driving current in advance to compensate for the influence that the held data will have when the gate is subsequently turned on, ensuring the LED reaches the desired brightness value more accurately
2Speed
If the gate is turned on quickly to update data, then the response time is reduced, but there is insufficient time for the LED to converge to the desired brightness value
Solution Approach 1:
The patent divides the grayscale period into two distinct time periods: a first time period when the gate is off and a second time period when the gate is on. By applying different control values to these segmented periods, the system can maintain fast gate switching while ensuring the LED has adequate time to converge to the desired brightness during the second time period
Solution Approach 2:
The first control value is applied in advance during the first time period to prepare the LED for the upcoming gate-on state. This preliminary adjustment ensures that when the gate is turned on quickly, the LED is already positioned closer to the target brightness, reducing the convergence time required during the second time period
3Device complexity
If a single control value is used for the entire grayscale period, then the control process is simple, but the previous data influences the current LED brightness and prevents accurate brightness control
Solution Approach 1:
The patent segments the control process into two distinct control value applications within one grayscale period: a first control value for the first time period and a second control value for the second time period. This segmentation enables precise brightness control by addressing the different states of the gate (off and on) with appropriate control values, eliminating the influence of previous data while maintaining manageable control complexity
Solution Approach 2:
The patent implements dynamic control by adjusting the control value based on the gate state and time period. The control value changes from the first control value to the second control value during the grayscale period, allowing the system to adapt to the changing conditions and achieve accurate brightness control without excessive complexity
Data Source
AI summary
An electronic device comprises: a memory to store an image input; a backlight unit; a driving unit to output a driving current to the backlight unit; and a processor to identify, based on a grayscale value of the image, a first intensity of the driving current corresponding to one from among a plurality of time sections of a backlight dimming section, obtaining, based on the identified first intensity, a first control value that allows control of an intensity of the driving current, providing a second control value, which is greater than a first control value to the driving unit, that allows the driving unit to output a driving current of a second intensity that is greater than the first intensity, and provide the first control value to the driving unit that allows the driving unit to output the driving current of the first intensity during the one time section.