Collimating Reflective Polarizer with Concave Microlenses
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Solution Overview
Problem
Conventional reflective polarizers in backlights for display devices face inefficiencies in light recycling and brightness enhancement due to the lack of effective collimation and diffusion, particularly when combined with other reflective surfaces, leading to suboptimal performance and thickness constraints in thinner constructions.
Innovation Solution
Incorporating a collimating reflective polarizer with an array of concave microlenses on its surface, which can be randomly or regularly arranged, and optionally featuring microfeatures like beads or prisms, to enhance light collimation and diffusion, thereby improving backlight efficiency and enabling thinner constructions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional reflective polarizers are used in backlights, then light recycling and brightness enhancement are achieved, but collimation and diffusion effectiveness are insufficient leading to suboptimal performance
Solution Approach 1:
The patent combines a reflective polarizer with a microlens array into a single integrated optical film structure. The microlens array is formed directly on the reflective polarizer substrate, merging the light recycling function of the polarizer with the collimation function of the microlenses, thereby achieving both brightness enhancement and effective collimation simultaneously
Solution Approach 2:
The optical film is constructed as a composite structure comprising a reflective polarizer layer and a microlens array layer. This composite design integrates materials with different optical properties - the polarizer for light recycling and the microlenses for collimation - to achieve superior overall performance that neither component could achieve alone
2Reliability
If standard recycling cavities are used, then light recycling performance is maintained, but the construction thickness is increased reducing design flexibility
Solution Approach 1:
The patent merges the functions of the reflective polarizer and the microlens array into a single integrated film, eliminating the need for separate recycling cavity structures. This integration maintains effective light recycling performance while significantly reducing the overall construction thickness, thereby improving design flexibility for thin-display applications
3Reliability
If microlens arrays are added to reflective polarizers, then collimation effects are enhanced, but device complexity increases
Solution Approach 1:
The patent merges the reflective polarizer and microlens array into a single integrated optical film, where the microlens array is formed directly on the polarizer substrate. This integration enhances collimation effects while reducing device complexity by eliminating the need for separate components and simplifying the overall optical system architecture
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 combination of a collimating reflective polarizer with concave microlenses and microfeatures achieves desired collimation effects with adequate diffusion, enhancing backlight efficiency and allowing for thinner designs while maintaining performance comparable to standard recycling cavities, thus offering greater design flexibility and improved light utilization.
Implementation Method 1
the collimating reflective polarizer has a transmission along a pass axis at normal incident of Tpassnormal for p-pol light and a transmission along a pass axis at 60 degrees incidence of Tpass60 for p-pol light
Implementation Method 2
Reflective polarizers substantially transmit light having one polarization state while substantially reflecting light having an orthogonal polarization state
Implementation Method 3
an array of concave microlenses disposed on a major surface of the collimating reflective polarizer
Implementation Method 4
Microreplicated films having a plurality of light directing elements may be used to change the angular distribution of light
Implementation Method 5
The microfeatures may include beads... the microfeatures include convex lenses or prisms
Data Source
AI summary
Optical films are disclosed. More particularly, optical films including a collimating reflective polarizer are disclosed. The optical films are useful in backlights, and in particular backlight recycling cavities. Constructions suitable with both edge-lit and direct-lit backlights are disclosed.