Backlight Current Control Circuit for LCD Flicker Reduction
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Solution Overview
Problem
Existing backlight devices for LCD panels face challenges in maintaining consistent light emission from light-emitting diode channels for one frame, leading to potential flicker issues and an inability to smoothly represent differences in luminance within the low gray range.
Innovation Solution
A backlight device with a current control integrated circuit that divides light-emitting diode channels into control groups, allowing for per-control group control of driving currents using sampling voltages derived from column signals, and employing a zoom control signal to adjust the gain for improved luminance representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the backlight device performs dimming control, then the light emission from light-emitting diode channels can be adjusted, but the light emission cannot be maintained sufficiently for one frame, causing flicker
Solution Approach 1:
The patent divides the light-emitting diode channels into multiple control groups, with each group independently controllable through separate current control integrated circuits. This segmentation allows precise control of light emission in each group, enabling the system to maintain sufficient light emission for one frame while reducing flicker through coordinated control of multiple groups.
2Use of energy by moving object
If the backlight provides low luminance for horizontal period, then energy consumption is reduced, but the difference in luminance between low luminance levels appears more pronounced to viewers
Solution Approach 1:
The patent applies different control strategies to different control groups based on their luminance levels. For low luminance regions, the system uses enhanced current control to maintain uniform luminance distribution, while high luminance regions use standard control. This local differentiation prevents the viewer from perceiving pronounced luminance differences in dark gray areas while maintaining energy efficiency.
Solution Approach 2:
The system dynamically adjusts the driving current parameters for different control groups based on the required luminance output. By changing current parameters adaptively, the system can maintain consistent luminance perception across different brightness levels while optimizing energy consumption, thereby reducing the visible difference in luminance between low luminance levels.
3Device complexity
If the backlight device employs simple control design, then device complexity is reduced, but the ability to maintain light emission for one frame and eliminate flicker is compromised
Solution Approach 1:
The patent employs current control integrated circuits that perform multiple functions: they control driving current for light emission, maintain luminance consistency, and eliminate flicker. By making the control circuit multi-functional, the system achieves reliable light emission maintenance without proportionally increasing overall device complexity, as a single circuit type handles multiple control tasks.
4Measurement precision
If the backlight device uses per-channel control, then light emission can be precisely controlled, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of implementing independent control for each individual light-emitting diode channel, the patent segments the channels into control groups where multiple channels share a common control circuit. This segmentation approach maintains sufficient control precision for light emission while significantly reducing device complexity and manufacturing difficulty compared to true per-channel control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively maintains light emission for one frame, reduces or eliminates flicker, and enables smooth representation of luminance differences in the low gray range, ensuring high reliability and quality of light for LCD panels.
Implementation Method 1
The backlight device includes light-emitting diode channels using LEDs as light sources. The light-emitting diode channels can emit light to provide the backlight.
Data Source
AI summary
Proposed are a backlight device for display and a current control integrated circuit therefor, the current control integrated circuit includes a plurality of driving current control units sharing a column signal for backlight and controlling driving currents of a predetermined number of light-emitting diode channels belonging to the same control group, wherein the plurality of the driving current control units receive the column signal for the control group and the zoom control signal in a shared manner and sequentially receive row signals, respectively, and wherein each of the plurality of driving current control units generates the sampling voltage that results from sampling the column signal using the row signal, and controls the driving current for light emission from the light-emitting diode channel using the sampling voltage, thereby enabling a gain for conversion of the driving current by the sampling voltage to be controlled with the zoom control signal.