LED Backlight Driving Circuit for Luminance Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The inconsistency in screen luminance of liquid crystal display apparatus due to differences in turn-on voltage and power usage among LEDs in the backlight module, leading to non-uniform luminance across the display.
Innovation Solution
A driving circuit and method that detects and adjusts the current settings for each light-emitting element series to equalize their power usage, ensuring consistent luminance by comparing and controlling the power values between series until they are equal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If constant current mode is used to drive LED series, then the control method is simple, but the luminance consistency between different LED series deteriorates due to turn-on voltage differences
Solution Approach 1:
The patent transitions from static constant current control to dynamic constant power control. The driving circuit dynamically adjusts the driving current for each LED series based on its actual power consumption, ensuring that all series operate at the same power level. This dynamic adjustment compensates for turn-on voltage differences and maintains luminance consistency across the display.
Solution Approach 2:
The patent changes the control parameter from constant current to constant power. By controlling the power consumption of each LED series to be equal, the system addresses the luminance inconsistency caused by turn-on voltage variations. The driving circuit calculates and adjusts current values based on power equality, transforming the control approach to achieve uniform luminance output.
2Illumination intensity
If different driving currents are applied to compensate for turn-on voltage differences, then luminance consistency improves, but the device complexity increases due to individual series control requirements
Solution Approach 1:
The driving circuit integrates multiple functions into a single unified control system. It simultaneously performs voltage detection, power calculation, and current adjustment for all LED series through a centralized processing unit. This multi-functional approach maintains luminance consistency while avoiding the need for separate control circuits for each series, thus managing complexity effectively.
Solution Approach 2:
The patent implements a feedback mechanism where the driving circuit continuously monitors the actual power consumption of each LED series and adjusts the driving current accordingly. The processing unit receives feedback on voltage and current values, calculates power consumption, and modifies current settings to maintain equal power across all series, ensuring luminance consistency through closed-loop control.
3Illumination intensity
If individual LED series power consumption is monitored and adjusted, then screen luminance uniformity improves, but the measurement and detection complexity increases
Solution Approach 1:
The patent merges the detection and measurement functions into a single integrated processing unit that handles all LED series simultaneously. The driving circuit combines voltage detection, current measurement, and power calculation in one unified system, simplifying the measurement process compared to individual series monitoring. This consolidation reduces detection complexity while achieving uniform luminance control.
Data Source
AI summary
A driving circuit, a driving method and a display apparatus are provided. The driving method is provided for driving a light-emitting unit including a first light-emitting element series and a second light-emitting element series connected in parallel and connected to a processing unit and a driving unit of a driving circuit. The processing unit detects a first voltage value and a second voltage value. The driving unit detects and transmits a first current value and a second current value to the processing unit. The processing unit determines and compares a first power value and a second power value. When the first and second power values are different, the processing unit controls the driving unit to adjust a driving current setting of the light-emitting element series until the first and second power values are equal. The invention ensures luminance consistency of different light-emitting element series and the luminance uniformity of display apparatus.