Monolithic Light Guiding Plate for LCD Backlight Uniformity
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Solution Overview
Problem
Backlight assemblies in liquid crystal display (LCD) devices suffer from light loss due to refractive index differences between layers, leading to non-uniform luminance and high manufacturing costs due to numerous separate optical sheets, and the hot spot phenomenon with point-type light sources like LEDs.
Innovation Solution
A monolithic light guiding and dispersing plate with parallel waveguides and light reflecting structures, such as partial ellipse and triangular protrusions, that redirects and disperses light without the need for additional optical sheets, improving luminance uniformity and reducing manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple separate optical sheets are used in backlight assemblies, then specific optical functions (light guiding, diffusion, prism effects) can be achieved, but device complexity and manufacturing cost increase due to the large number of separate parts
Solution Approach 1:
The patent combines multiple separate optical sheets (light guiding plate, diffusion sheet, prism sheet) into a single integrated light guiding plate with multiple functional layers. Each layer performs a specific optical function (light guiding, diffusion, prism effects) but all are merged into one monolithic structure, eliminating the need for separate sheets and reducing assembly complexity.
Solution Approach 2:
The integrated light guiding plate serves multiple functions simultaneously: it guides light from the edge-mounted LED source, diffuses light to eliminate hot spots, creates prism effects for viewing angle control, and provides structural support. This multi-functional design replaces several separate components with a single universal optical element.
2Reliability
If multiple layers with different refractive indexes are stacked, then optical functions are achieved, but light loss increases due to refraction at each interface
Solution Approach 1:
The patent carefully controls the refractive index parameters of each layer within the integrated light guiding plate. By optimizing the refractive index gradient between layers and matching interfaces, the design minimizes refraction losses while maintaining necessary optical functions. The continuous integration eliminates air gaps that would cause additional refraction.
Solution Approach 2:
The light guiding plate uses composite material structures with different refractive indexes arranged in specific configurations. The materials are selected and combined to achieve optimal light guiding, diffusion, and prism effects while minimizing interfacial losses through proper material selection and interface design.
3Illumination intensity
If point-type light sources like LEDs are used, then high luminance and color representation are achieved, but hot spot phenomenon occurs due to constructive and destructive interference
Solution Approach 1:
The patent segments the light path by introducing multiple functional layers within the light guiding plate. The diffusion layer breaks up concentrated LED light into scattered rays, while the prism layer further segments and redirects light at different angles. This segmentation of the optical path eliminates hot spots by distributing light uniformly across the display area.
Solution Approach 2:
The integrated light guiding plate acts as an intermediary between the LED light source and the display panel. It mediates the light by guiding it along controlled paths, diffusing hot spots, and redistributing light uniformly before it reaches the display panel, thereby eliminating the harmful hot spot effect while preserving LED luminance advantages.
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 luminance uniformity and reduces manufacturing costs by eliminating the need for separate optical sheets, while effectively addressing the hot spot phenomenon even with LED light sources, achieving improved optical properties for LCD devices.
Implementation Method 1
a monolithic light guiding and dispersing plate which guides light generated by the edge-mounted light source along parallel waveguides
Implementation Method 2
redirects the guided light toward and disperses the redirected light to the display panel
Implementation Method 3
a first surface which is adjacent to the light receiving surface and on which a plurality of first protrusions (waveguides) are defined to extend longitudinally in a first direction parallel to one another
Data Source
AI summary
A monolithic light guiding and dispersing plate is provided in a backlighted display panel for receiving input light from one or more edge sources and for guiding the received light throughout the plate for substantially uniform reflection upwardly and substantially uniform dispersal toward an image forming plane located above the light guiding and dispersing plate. In one embodiment, the light guiding and dispersing plate has a light receiving surface upon which the light generated by an edge light source is incident, a top major surface which is adjacent to the light receiving surface and on which a plurality of first protrusions are formed and elongated in a first direction, wherein the first protrusions have cross-sections in the shapes of partial ellipses. The plate further has a bottom major surface in which light reflecting recesses are defined to reflect light upwardly towards the top major surface.