Backlight Unit Reflective Film Design for Uniform Luminance
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Solution Overview
Problem
The firefly phenomenon in LCDs, characterized by dark and bright spots due to non-uniform backlight distribution, occurs when the edge of the light guide plate is too close to LEDs, leading to suboptimal display quality and a broader frame.
Innovation Solution
A backlight unit with a light guide plate and LEDs, featuring a first reflective film with lower reflectivity opposite to each LED and a second reflective film with higher reflectivity opposite to the gap between LEDs, ensuring uniform luminance by strategically placing these films to manage light distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the edge of the light guide plate is arranged in the region after light beams from adjacent LEDs have converged, then the firefly phenomenon is avoided, but the distance between the LEDs and the display panel increases, resulting in a broader frame
Solution Approach 1:
The patent applies local quality by differentiating the reflective film structure into two distinct regions: a first reflective film with lower reflectivity positioned opposite to each LED, and a second reflective film with higher reflectivity positioned opposite to gaps between LEDs. This localized differentiation allows the light guide plate to be placed closer to the display panel while maintaining uniform light distribution and eliminating the firefly phenomenon.
Solution Approach 2:
The patent changes the reflectivity parameter of the reflective films to solve the contradiction. By setting the first reflective film's reflectivity lower than the second reflective film's reflectivity, the system achieves uniform backlight distribution even when the light guide plate is positioned closer to the display panel, thus eliminating the firefly phenomenon without increasing frame width.
2Length of stationary object
If the light guide plate is positioned closer to the display panel, then the frame width is reduced, but the firefly phenomenon occurs due to non-uniform backlight distribution
Solution Approach 1:
The patent uses local quality by creating spatially differentiated reflective regions. The first reflective film (lower reflectivity) is positioned in regions opposite to LEDs, while the second reflective film (higher reflectivity) is positioned in regions opposite to gaps between LEDs. This local differentiation compensates for the non-uniform light distribution that would otherwise cause the firefly phenomenon, enabling the light guide plate to be positioned closer to the display panel.
Solution Approach 2:
The patent converts the harmful effect of non-uniform light distribution into a benefit by strategically positioning reflective films with different reflectivities. The reflective films are placed to reflect light from dark regions (gaps between LEDs) more strongly and reduce reflection from bright regions (opposite to LEDs), thereby converting the inherent non-uniformity into uniform backlight distribution.
3Illumination intensity
If the reflectivity of the reflective film is increased to compensate for light loss, then the backlight intensity is improved, but the uniformity of light distribution deteriorates
Solution Approach 1:
The patent resolves this contradiction by applying local quality through spatially differentiated reflectivity. Instead of using a uniform high-reflectivity film throughout, the system uses a first reflective film with lower reflectivity in regions opposite to LEDs and a second reflective film with higher reflectivity in regions opposite to gaps between LEDs. This localized approach maintains overall uniformity while providing necessary light intensity compensation.
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 eliminates the firefly phenomenon by achieving uniform backlight distribution, enhancing display quality while reducing the frame size by allowing a closer proximity of the light guide plate to the LEDs.
Implementation Method 1
A first reflective film disposed correspondingly on a backlight side of a region opposite to each of the LEDs on the light guide plate; A second reflective film including at least one first sub-reflective film, the first sub-reflective film being disposed correspondingly on a backlight side of a region opposite to a gap between two adjacent LEDs on the light guide plate
Data Source
AI summary
A backlight unit (10) and a display device are provided. The backlight unit (10) comprises a light guide plate (101), and a light source (102), a first reflective film (101), and a second reflective film (104). The light source (102) includes a plurality of LEDs (1021) uniformly arranged. The first reflective film (103) is disposed correspondingly on a backlight side of a region opposite to each of the LEDs on the light guide plate (101); The second reflective film (104) includes at least one first sub-reflective film (1041), the first sub-reflective film (1041) being disposed correspondingly on a backlight side of a region opposite to a gap between two adjacent LEDs on the light guide plate (101). A reflectivity of the first reflective film is less than a reflectivity of the second reflective film, and a distance between the light guide plate (101) and the LEDs is less than a distance between an intersection of light beams emitted by two adjacent LEDs and the LEDs, and, a width of the frame of the display device can be reduced.