Direct Backlight Fluorescent Tube Arrangement for LCD Brightness Uniformity
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Solution Overview
Problem
Existing direct backlight units for liquid crystal display devices face challenges in achieving uniform brightness distribution, particularly in ensuring high brightness at the center and reducing brightness variations at the upper and lower ends, due to variations in fluorescent tube brightness and arrangement intervals.
Innovation Solution
The solution involves arranging pairs of fluorescent tubes at irregular intervals, with the narrowest interval at the boundary of the display area, and broadening intervals further from this boundary, while also varying the number of pairs on either side of the boundary to optimize brightness distribution. This arrangement includes using a support member to maintain consistent tube spacing and a reflector with convex portions to enhance light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fluorescent tubes are arranged at regular intervals to achieve uniform brightness distribution, then the manufacturing precision is improved, but the brightness uniformity deteriorates due to variations in individual tube brightness
Solution Approach 1:
The patent applies local quality by varying the arrangement intervals of fluorescent tubes based on their individual brightness characteristics. Tubes with higher brightness are positioned at larger intervals while dimmer tubes are placed at smaller intervals, creating a non-uniform arrangement that compensates for individual tube variations and achieves overall brightness uniformity across the display area.
Solution Approach 2:
The patent changes the arrangement interval parameter from a constant value to a variable value that depends on the brightness characteristics of individual fluorescent tubes. By adjusting the interval parameter locally for each tube position, the system achieves uniform brightness distribution despite variations in tube performance.
2Illumination intensity
If fluorescent tubes are arranged with narrower intervals at the center to increase center brightness, then the illumination intensity at the center is improved, but the brightness distribution uniformity deteriorates with excessive variation at upper and lower ends
Solution Approach 1:
The patent implements local quality by creating different arrangement interval patterns in different regions of the display area. The center region has narrower intervals to boost center brightness, while the upper and lower end regions have progressively larger intervals to reduce brightness there, achieving an overall uniform brightness distribution across the entire display area.
Solution Approach 2:
The patent applies asymmetry by using different arrangement interval configurations for different vertical positions. The arrangement is not uniformly symmetric but rather asymmetrically optimized for each region, with the narrowest intervals at the center and progressively wider intervals toward the ends, creating a tailored brightness distribution.
3Illumination intensity
If the number of fluorescent tube pairs is made different on either side of the boundary to optimize brightness distribution, then the brightness distribution is improved, but the device complexity increases
Solution Approach 1:
The patent applies asymmetry by deliberately making the number of fluorescent tube pairs different on either side of the boundary. This asymmetric configuration allows optimization of brightness distribution in regions where tube variations are more pronounced, achieving better overall uniformity despite the increased configurational complexity.
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 configuration increases brightness at the center and reduces brightness variations across the display area, effectively achieving a more uniform and desirable brightness distribution similar to CRT televisions, while minimizing the impact of fluorescent tube brightness variations.
Implementation Method 1
The backlight unit is formed of, for example, a fluorescent tube such as a cold cathode fluorescent tube (CFL)
Implementation Method 2
The direct backlight unit converts linear lights from the fluorescent tubes into a planar light by the optical member, and irradiates the image display area of the liquid crystal display panel with the light
Implementation Method 3
a liquid crystal display device using a liquid crystal display panel
Data Source
AI summary
In a liquid crystal TV, there is provided a direct back light for increasing brightness in the vicinity of the center of a screen. Plural fluorescent tubes are used for backlight, and the respective two fluorescent tubes are paired and driven. The arrangement intervals of the respective pairs are made smallest in the vicinity of the center of the screen to increase the brightness in the vicinity of the center of the screen. The use of the paired fluorescent tubes is to alleviate a variation of the brightness in each of the fluorescent tubes.