Light Diverting Layer for Backlit Display Uniformity
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Solution Overview
Problem
Backlit liquid crystal displays (LCDs) face challenges in achieving uniform illumination due to the linear arrangement of cold cathode fluorescent lamps, leading to bright stripes and darker regions, which can be exacerbated by limited space for light to spread uniformly between lamps, resulting in non-uniform brightness across the display.
Innovation Solution
The implementation of a light diverting layer with specific light-diverting surfaces between the light sources and a diffuser in a backlit display unit, along with a specular back reflector and a diffuser layer, to manage light distribution and enhance brightness uniformity, utilizing a ratio of light source spacing to diffuser distance of at least 3 to optimize illumination uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a diffuser plate is used to smooth the illumination profile, then brightness uniformity is improved, but the separation distance between the diffuse reflector and diffuser must be sufficiently large to allow light to spread uniformly, increasing device thickness
Solution Approach 1:
A light diverting layer is introduced as an intermediary component between the light sources and the diffuser plate. This layer includes light diverting members that redirect light rays to reach the diffuser more uniformly, eliminating the need for large separation distances while maintaining brightness uniformity.
Solution Approach 2:
The light diverting layer introduces an additional optical dimension by using light diverting members with specific geometries (such as prisms or lenses) that redirect light in controlled directions. This dimensional approach to light management allows uniform illumination without increasing the separation distance in the vertical dimension.
2Device complexity
If light sources are positioned closer together to reduce device thickness, then device complexity is reduced, but brightness uniformity deteriorates due to insufficient space for light to spread uniformly
Solution Approach 1:
The light diverting layer serves as a mediator that enables closer spacing of light sources while maintaining brightness uniformity. The light diverting members redirect light rays from closely spaced sources to distribute them uniformly across the diffuser, compensating for the reduced separation distance.
Solution Approach 2:
The invention changes the optical parameters of the light path by introducing the light diverting layer with specific refractive indices, geometries, and orientations. These parameter changes allow the system to achieve uniform illumination with closer light source spacing by modifying how light propagates through the system.
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 significantly improves brightness uniformity across the display, maintaining high brightness levels while reducing non-uniformity, even at larger display sizes, by effectively redistributing light to achieve a more uniform illuminance profile.
Implementation Method 1
A light diverting layer is disposed between the one or more light sources and the diffuser. The light diverting layer comprises a first light-diverting surface facing the one or more light sources... The light diverting layer also comprises a second light-diverting surface facing the diffuser
Implementation Method 2
A diffuse reflector is used behind the lamps to direct light towards the viewer
Implementation Method 3
a diffuser plate is typically used to smooth the illumination profile at the back of the LCD device
Data Source
AI summary
A directly illuminated display unit has a display panel and one or more light sources disposed behind the display panel. A diffuser is disposed between the one or more light sources and the display panel, and a light diverting layer is disposed between the one or more light sources and the diffuser. The light diverting layer has a first light-diverting surface facing the one or more light sources and a second light diverting surface facing the display panel. The light diverting layer diverts light passing from the one or more light sources to the diffuser, thus improving the uniformity of the light in the display unit.