Integrated Light Diffusing Sheet for LCD Backlighting
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Solution Overview
Problem
Current light diffusing systems for LCDs face challenges in efficiently directing light into desired directions while minimizing the appearance of speckle and maintaining brightness, often requiring multiple films that increase cost and complexity.
Innovation Solution
The development of enhanced light diffusing sheets featuring prismatic structures and micro-bodies with specific refractive indices and alignments, which provide improved collimation and control over light distribution, reducing the need for multiple films by integrating light directing and diffusing functions into a single sheet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple diffusion films are used to direct light and increase brightness, then light distribution control is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines multiple diffusion films with different functions (symmetric diffuser, asymmetric diffuser, and light directing prismatic film) into a single integrated light diffusing sheet. This merging eliminates the need for multiple separate films while maintaining the ability to control light distribution in both x and y directions and direct light into desired directions.
Solution Approach 2:
The integrated light diffusing sheet performs multiple functions simultaneously: it acts as both a symmetric diffuser (for x-direction diffusion) and an asymmetric diffuser (for y-direction diffusion), and also functions as a light directing element with prismatic structures. This multi-functionality reduces the overall system complexity while achieving the desired light control.
2Adaptability or versatility
If symmetric diffuser is used to spread light in all directions to increase viewing angle, then viewing angle is improved, but light is scattered into undesired directions and brightness decreases
Solution Approach 1:
The patent employs asymmetric light transmissive micro-bodies with different diffusion properties in different directions. The asymmetric micro-bodies are configured to diffuse light differently in the x-direction versus the y-direction, allowing controlled viewing angle enhancement in specific directions while maintaining brightness in the primary viewing direction.
3Illumination intensity
If asymmetric diffuser films are used to spread light in different directions, then light distribution control is improved, but device complexity increases due to multiple films
Solution Approach 1:
The patent integrates both symmetric and asymmetric diffusion functions into a single light diffusing sheet by incorporating asymmetric light transmissive micro-bodies within a unified matrix structure. This eliminates the need for separate symmetric and asymmetric diffuser films while maintaining directional light distribution control.
4Object-affected harmful factors
If diffusers are spaced apart to reduce speckle appearance, then speckle is reduced, but number of films increases and brightness decreases
Solution Approach 1:
The patent reduces speckle appearance by optimizing the size, shape, and distribution parameters of the asymmetric light transmissive micro-bodies within the integrated sheet. By carefully controlling these parameters, the speckle effect is minimized while maintaining brightness and eliminating the need for multiple spaced-apart diffuser films.
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
These sheets effectively direct light into desired directions, reduce speckle appearance, and enhance brightness by optimizing light distribution, thereby simplifying manufacturing and reducing costs while improving display performance.
Implementation Method 1
light directing structures on at least one surface of the diffusing sheet. These light directing structures are prismatic structures that can direct light into desired directions
Implementation Method 2
light transmissive micro-bodies dispersed throughout the light transmissive matrix, having a refractive index, n2, which is different from n1
Data Source
AI summary
A light transmitting diffusing sheet can be used in backlighting systems for liquid crystal displays (LCDs). Such displays are typically used in televisions, computer monitors, laptop computers and handheld devices such as mobile phones. Embodiments of the light diffusing sheets are suitable for use with both cold-cathode fluorescent (CCFL) and light emitting diode based backlighting systems. Desired light transmitting properties in the light transmitting diffusing sheet have been achieved by modifying both the volume and surface features of the sheet. Embodiments of this invention when used as part of the backlighting assembly for a LCD system results in improved brightness and controlled viewing angles. In one embodiment, substantially asymmetric particles in the volume of the sheet are combined with a ridged structure on one surface of the sheet. The use of the sheet removes the need for separate prismatic films and diffusing sheets, while also optimizing the light transmitting properties of these two elements.