Backlight Drive Circuit Amplitude Control for LCD Scan Effect
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Solution Overview
Problem
Liquid crystal display devices face a trade-off between motion blur reduction (scan effect) and luminous efficiency, where improving one aspect typically deteriorates the other, and existing backlight scanning technologies require motion speed detection to adjust lighting duty ratios and drive currents effectively.
Innovation Solution
A display device with a controller that adjusts the output of a drive signal based on duty ratio and amplitude characteristics, dividing luminance into regions with specific change rates for the drive signal, allowing for a favorable trade-off between scan effect and luminous efficiency regardless of motion speed, by boosting the amplitude of the drive signal in certain regions and maintaining constant or reduced amplitude in others.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the lighting duty ratio is decreased to improve the scan effect, then motion blur is suppressed, but the drive current must be increased which deteriorates luminous efficiency
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting both the lighting duty ratio and the drive current amplitude based on detected motion speed. When motion speed is high, the system decreases the lighting duty ratio to enhance the scan effect while simultaneously increasing the drive current amplitude to compensate for reduced lighting time, thereby maintaining luminous output and efficiency.
Solution Approach 2:
The system implements dynamics by making the drive signal characteristics adaptive rather than fixed. The controller continuously monitors motion speed and dynamically adjusts the drive current amplitude and lighting duty ratio in real-time, allowing the system to optimize the trade-off between scan effect and luminous efficiency according to actual viewing conditions.
2Use of energy by moving object
If the drive current is decreased to improve luminous efficiency, then power consumption is reduced, but the lighting duty ratio must be increased which impairs the scan effect
Solution Approach 1:
The patent uses parameter changes to simultaneously optimize both luminous efficiency and scan effect. By increasing the drive current amplitude, the system can maintain adequate luminous output with a higher lighting duty ratio, thus improving luminous efficiency while still providing sufficient scan effect through the combined action of amplitude and duty ratio adjustment.
Solution Approach 2:
The dynamic adjustment mechanism allows the system to adapt to different motion speeds by optimizing the combination of drive current amplitude and lighting duty ratio. When motion speed is low, the system can use higher drive current with higher duty ratio to maximize luminous efficiency, and when motion speed is high, it adjusts the parameters to prioritize scan effect.
3Manufacturing precision
If backlight scanning is implemented to suppress motion blur, then image clarity is improved, but the system complexity increases due to the need for motion speed detection and multiple parameter adjustments
Solution Approach 1:
The controller is designed to perform multiple functions: it detects motion speed, determines appropriate drive signal parameters, adjusts lighting duty ratio, and modulates drive current amplitude. By consolidating these functions into a single controller, the patent reduces overall system complexity while maintaining the ability to suppress motion blur effectively.
Data Source
AI summary
A liquid crystal display device includes a liquid crystal panel, a backlight panel and a backlight drive circuit which outputs drive current of the backlights, the duty ratio and the amplitude of which are changeable. The backlight drive circuit outputs the drive current based on duty ratio characteristics that the duty ratio is greater as the luminance of the backlights is higher and amplitude characteristics that is divided with a predetermined luminance as a boundary into the first and second regions, and that the change rate of the amplitude of the drive current with respect to the luminance is less than or equal to the predetermined change rate in the first region, and the change rate of the amplitude of the drive current with respect to the luminance is greater than the predetermined change rate.