Backlight Light Diverting Layer for Uniform Illumination
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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 non-uniform brightness, which is exacerbated by the limited space for light to spread uniformly between lamps.
Innovation Solution
A light diverting layer with faceted or curved surfaces is introduced between the light sources and the diffuser in the backlight unit, redirecting light to improve uniformity by refracting it in multiple directions, reducing non-uniformity in illumination across the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple light sources are positioned behind the display panel to achieve sufficient brightness, then the display brightness is improved, but the illumination uniformity deteriorates due to bright stripes and darker regions between lamps
Solution Approach 1:
A light diverting layer is introduced as an intermediary component between the light sources and the display panel. This layer contains light diverting members that redirect light from the linear lamp sources in multiple directions, effectively mediating between the non-uniform light emission and the requirement for uniform illumination across the display surface.
Solution Approach 2:
The light diverting members redirect light from the one-dimensional linear lamp sources into two-dimensional angular distributions. By changing the propagation dimensionality of light, the system transforms concentrated linear illumination into dispersed area illumination, achieving uniform brightness across the display panel.
2Volume of moving object
If the separation between the diffuse reflector and the diffuser is reduced to save space, then the device structure is compacted, but the luminance uniformity deteriorates due to insufficient space for light to spread uniformly
Solution Approach 1:
The light diverting members redirect light into angular distributions, effectively utilizing the third dimension (angular space) to achieve uniform illumination. This allows the system to maintain compact physical separation while still providing sufficient optical path length for uniform light distribution through directional control rather than spatial expansion.
Solution Approach 2:
The light diverting members change the angular parameters of light propagation. By redirecting light at specific angles, the system transforms the light distribution pattern without requiring increased physical separation, thereby maintaining compact device volume while achieving uniform luminance.
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 enhances the uniformity of illumination, resulting in a more consistent and brighter image across the display, addressing the issue of brightness maxima above and minima between light sources.
Implementation Method 1
A light diverting layer with faceted or curved surfaces is introduced between the light sources and the diffuser in the backlight unit, redirecting light to improve uniformity by refracting it in multiple directions
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 light source unit 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 light diverting members on a first side of the light diverting layer facing the diffuser. Surfaces of the light diverting members are disposed at more than one angle relative to a normal to the light diverting layer and also include one or more sharp changes of surface slope. The light diverting members spread the illumination light so as to be more uniform. Different light diverting members can have different apex angles. Also, different sides of a light diverting member can have best fit centers of curvature that are non-coincident.