Reflective Sheet Dimming Areas Backlight Brightness Uniformity
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Solution Overview
Problem
Conventional direct-lit backlight modules suffer from uneven brightness due to varying light intensity distribution, resulting in poor brightness uniformity across the surface light source.
Innovation Solution
A reflective sheet with distinct dimming areas and perforations is designed, where the distance and dimensions of the dimming features differ, and is integrated with a fixing element to optimize light reflection and absorption, thereby reducing luminance differences between areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light emitting diodes are used in a direct-lit backlight module, then the light intensity is sufficient, but the brightness uniformity across the surface light source deteriorates due to varying light intensity distribution
Solution Approach 1:
The reflective sheet introduces different dimming means at different locations (first dimming means at the center, second dimming means at the periphery), creating local variations in light reflection characteristics. This local quality differentiation compensates for the non-uniform light intensity distribution from multiple LEDS, achieving overall brightness uniformity.
Solution Approach 2:
The patent changes the geometric parameters (depth, aperture size) of the dimming means at different locations on the reflective sheet. The first dimming means has different depth/aperture parameters compared to the second dimming means, allowing optimization of light reflection for different spatial positions to achieve uniform brightness.
2Illumination intensity
If the light emitting diodes are arranged to provide sufficient light, then the brightness in the middle area increases, but the brightness uniformity deteriorates because the surrounding areas receive less light
Solution Approach 1:
The reflective sheet applies different dimming characteristics to different regions: the first dimming means at the center region and the second dimming means at the periphery region. This local differentiation allows the middle area to maintain sufficient brightness while the periphery is adjusted to match, achieving uniform overall brightness.
Solution Approach 2:
The dimming means are designed with asymmetric parameters - the first dimming means at the center has different depth and aperture characteristics compared to the second dimming means at the periphery. This asymmetric design compensates for the asymmetric light distribution from LEDS, creating uniform brightness across the entire backlight module.
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 solution effectively reduces brightness differences between dimming areas, enhancing the uniformity of the overall brightness in the backlight module, improving the display's image contrast and brightness distribution.
Implementation Method 1
a reflective sheet with distinct dimming areas and perforations is designed, where the distance and dimensions of the dimming features differ, and is integrated with a fixing element to optimize light reflection and absorption
Implementation Method 2
optimize light reflection and absorption, thereby reducing luminance differences between areas
Data Source
AI summary
A reflective sheet comprises a plurality of perforations for extending a plurality of light-emitting elements therein, the reflective sheet further comprises a central line passing through its center, at least one first dimming area, and at least one second dimming area, and the distance between the at least one first dimming area and the central line is smaller than the distance between the at least one second dimming area and the central line. The light-emitting elements are distributed in the at least one first dimming area and the at least one second dimming area, the at least one first dimming area has a first dimming means, the at least one second dimming area has a second dimming means, the dimension of the first dimming means is different from the dimension of the second dimming means. Through the structural design of the reflective sheet, the luminance difference between the first dimming area and the second dimming area can be reduced, and the uniformity of the brightness in the whole area (Area Scan) can be improved. This invention also provides a backlight module and a display device including the reflective sheet.