Composite Light Guide Plate Segmentation for High-Speed Manufacturing
Solution Overview
Problem
Existing methods for producing thick light guide plates face challenges in replication fidelity and production efficiency, particularly in extrusion roll molding processes, which become ineffective at thicknesses above 1 mm, and injection molding requires large molds and high pressure, leading to poor dimensional stability and high costs.
Innovation Solution
A composite light guide plate is created using a patterned film and a pre-cut sheet joined by an adhesive layer, where the refractive indices of the three components are closely matched to ensure efficient light extraction and redirection, with the patterned film, adhesive layer, and pre-cut sheet having refractive indices related as nf≧na≧ns, and the process involves extrusion roll molding combined with coating and lamination for roll-to-roll manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If extrusion roll molding process is used for thick light guide plates (thickness > 1 mm), then production efficiency and line speed are maintained, but replication fidelity of light extraction micro-pattern deteriorates
Solution Approach 1:
The light guide plate is divided into two separate components: a patterned film with micro-patterns and a pre-cut sheet without patterns. The patterned film is produced using extrusion roll molding at high line speeds, while the pre-cut sheet is separately manufactured. This segmentation allows each component to be optimized independently, maintaining both high productivity and manufacturing precision.
Solution Approach 2:
The micro-patterns are transferred from the patterned film to the pre-cut sheet through a lamination process, adding a dimensional layer to the manufacturing approach. This allows the patterns to be applied after the base sheet is formed, enabling high-speed production of the patterned film while maintaining precise pattern replication on the final product.
2Ease of manufacture
If injection molding process is used for large light guide plates, then manufacturing capability is achieved, but mold size and injection pressure requirements increase leading to poor dimensional stability and high costs
Solution Approach 1:
The light guide plate is segmented into a patterned film and a pre-cut sheet, eliminating the need for a single large injection mold. The pre-cut sheet can be manufactured using extrusion or other suitable processes, while the patterned film is produced separately using roll molding with much smaller, more manageable equipment.
Solution Approach 2:
The micro-patterns are copied from the patterned film to the pre-cut sheet through lamination and transfer processes. This allows the complex micro-pattern features to be replicated without requiring the entire large light guide plate structure to be molded in one operation, significantly reducing mold size and injection pressure requirements.
3Length of moving object
If light guide plate thickness is reduced to slim down LCD, then overall thickness and weight are reduced, but light coupling efficiency with light source deteriorates
Solution Approach 1:
The light guide plate incorporates localized micro-patterns on the patterned film that are strategically designed to enhance light extraction and coupling at specific locations. These local optical features compensate for the reduced overall thickness, maintaining light coupling efficiency despite the thinner profile of the light guide plate.
4Reliability
If refractive indices of patterned film, adhesive layer and pre-cut sheet are closely matched, then light extraction efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The patterned film, adhesive layer, and pre-cut sheet are designed with closely matched refractive indices to create optical homogeneity across the laminate structure. This reduces optical mismatches and improves light extraction efficiency. The extrusion roll molding process is used to produce the patterned film with controlled optical properties that match the other components.
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 approach enables the production of thick light guide plates with improved light extraction efficiency, maintaining high line speeds and production efficiency while minimizing scattering, waveguiding, and absorption losses, thus addressing the limitations of existing methods.
Implementation Method 1
a patterned film and a pre-cut sheet joined by an adhesive layer
Implementation Method 2
the refractive indices of the three components are closely matched to ensure efficient light extraction and redirection, with the patterned film, adhesive layer, and pre-cut sheet having refractive indices related as nf≧na≧ns
Implementation Method 3
minimizing scattering, waveguiding, and absorption losses
Data Source
AI summary
The present invention provides a composite light guide plate having a thickness of more than about 1 mm, for use in LCD backlights or in general illumination devices. In the fabrication method of the present invention the extrusion roll molding process is combined with coating and lamination steps to enable a cost effective roll-to-roll or roll-to-sheet manufacture of the thick composite light guide plate wherein one or both principal surfaces of the light guide plate contain a pattern to enable extraction and redirection of light by the light guide plate from a light source or multiple light sources placed at one or multiple edges of the light guide plate. The composite light guide plate comprises a patterned film and a pre-cut sheet joined together by an adhesive layer. In order to attain good light extraction efficiency the adhesive layer and the two constituent layers of the light guide plate must be optically matched such that the refractive indices of any two of the three materials of the composite light guide plate can differ by no more than 0.01.