Direct-Firing Backlight Uniformity via Segmented Light Sensing
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Solution Overview
Problem
Conventional side-firing LED backlights for LCD displays face challenges in producing uniform intensity and chrominance, especially in larger displays, due to variations in LED optical characteristics with temperature, drive current, and aging, and the difficulty in designing an adequate light guide for direct-firing configurations.
Innovation Solution
A direct-firing backlight system with multiple light sensors and a control system that measures and compares light emitted from independently controllable regions to reference values, allowing for real-time regulation of light intensity and chrominance across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a direct-firing LED backlight is used, then the backlight can provide a wider color gamut and longer operating life, but the uniformity of light intensity and chrominance across the display deteriorates
Solution Approach 1:
The backlight is divided into multiple independently controllable light emitting regions (e.g., 9 regions arranged in a 3x3 matrix), each with its own light sensors and control circuitry. This segmentation allows localized adjustment of light intensity and chrominance to compensate for variations across the display area, maintaining uniformity despite LED aging and temperature variations.
Solution Approach 2:
Each light emitting region is equipped with light sensors that continuously monitor the actual light output. The control system uses this feedback information to dynamically adjust the drive signals to LEDs, compensating for optical characteristic variations due to temperature, aging, and manufacturing tolerances, thereby maintaining consistent uniformity across the display.
2Stability of the object's composition
If multiple light sensors and independently controllable regions are implemented, then uniformity of backlighting is improved, but the device complexity increases
Solution Approach 1:
The control system integrates multiple functions into a unified architecture: a single microcontroller or control circuit receives signals from all light sensors, processes the feedback information, and generates adjusted drive signals for all LED regions. This merging reduces the need for separate control circuits for each region, managing complexity while maintaining uniformity.
Solution Approach 2:
The light sensors serve multiple functions: they monitor light intensity, detect chrominance variations, and provide feedback for both brightness and color uniformity control. This multi-functionality reduces the need for separate sensor types and simplifies the overall system architecture while achieving comprehensive uniformity 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 approach ensures uniform backlighting by independently controlling each light emitting region, maintaining consistent brightness and chrominance across the display, even in larger sizes, by using a plurality of light sensors and a control system to adjust drive signals based on measured data.
Implementation Method 1
a plurality of light sensors, each positioned to sense light produced by a corresponding one of the light emitting regions
Data Source
AI summary
A direct-firing backlight for a display is designed with a plurality of light emitting regions. Each of a plurality of light sensors is positioned to sense light produced by a corresponding one of the light emitting regions. A control system is operatively associated with the light sensors and light emitting regions. The control system receives information from the light sensors and, in response thereto, regulates light emitted from regions of a display. The regions of the display correspond to the light emitting regions of the direct-firing backlight. Various configurations of such a direct-firing backlight, and related methods, are also disclosed.