Backlight Unit Reflecting Member with Zoned Reflectance
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Solution Overview
Problem
Conventional direct type backlight units face issues with non-uniform luminance due to the characteristics of cold cathode fluorescent lamps, leading to decreased display quality, and existing solutions either increase the frame size, thickness, or manufacturing cost.
Innovation Solution
A backlight unit design with a reflecting member divided into regions with varying reflectance, where the region near the lamp electrodes has a higher reflectance than the middle region, to improve luminance uniformity without increasing the frame size or thickness, and maintaining low manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a reflector with uniform reflectance is used, then the structure is simple and manufacturing cost is low, but luminance uniformity deteriorates due to weak discharge regions near electrodes
Solution Approach 1:
The reflector is divided into multiple regions with different reflectance values. Specifically, the region corresponding to the electrode vicinity has higher reflectance (90-98%) compared to the middle region (80-90%), allowing localized compensation for the weak discharge areas near electrodes while maintaining overall luminance uniformity across the display panel
Solution Approach 2:
The reflector surface is segmented into distinct zones based on the luminance characteristics of the lamp regions they serve. By dividing the reflector into electrode-proximity regions and middle regions with different reflectance properties, the patent addresses the non-uniform luminance distribution caused by the lamp's discharge characteristics
2Illumination intensity
If inclined surfaces are added to side walls to improve luminance distribution, then luminance uniformity improves, but frame size and thickness increase
Solution Approach 1:
Instead of changing the geometric shape of the reflector (adding inclined surfaces), the patent changes the optical parameter (reflectance) of the reflector surface. By adjusting the reflectance values in different regions, the patent achieves luminance uniformity without modifying the overall frame dimensions or adding structural complexity
3Illumination intensity
If multiple reflectors with different reflectances are used, then luminance uniformity improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines multiple reflector regions with different reflectance properties into a single integrated reflector structure. This unified reflector can be manufactured as one piece with spatially varying reflectance characteristics, avoiding the complexity of assembling multiple separate reflector components while still achieving the desired luminance distribution
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
The design achieves improved luminance uniformity by adjusting reflectance in specific regions, suppressing luminance decreases near electrodes and end lamps, while maintaining a thin and cost-effective design.
Implementation Method 1
a reflecting member which reflects light from the lamps toward the display panel
Implementation Method 2
The cold cathode fluorescent lamp used in this lamp 5 converts ultraviolet rays generated by discharges across electrodes provided at both ends into visible rays by use of a fluorescent substance applied to an inner wall of a glass tube
Data Source
AI summary
Disclosed is a backlight unit which illuminates a display panel from a rear surface thereof, including at least: tubular lamps arranged in parallel to the panel; and a reflecting member which reflects light from the lamps toward the panel, wherein the reflecting member is divided into a first region opposed to an area near an electrode provided in an end portion of the lamp and a second region nearer to a middle area than the first region, the first region having a higher reflectance than the second region. In another backlight unit, a reflecting member is divided, with respect to the arrangement direction of the lamps, into an end lamp near region which is opposed to a lamp arranged in end portion and a middle region which is nearer to a middle area than the end lamp region, the end lamp region having a higher reflectance than the middle region.