Thin Lightguide With Turning Film For Angular Light Control
Solution Overview
Problem
Conventional light emitting devices with edge-lit configurations using rigid lightguides are thick and inflexible, limiting design configurations and illumination modes due to the thickness of the lightguides, which hinders the reduction of volume and overall thickness while maintaining sufficient light flux.
Innovation Solution
A light emitting device with a 0.5 millimeter thick lightguide featuring a cladding layer and a light turning film with light turning features that redirect frustrated totally internally reflected light, combined with a reflective spatial light modulator for diffused reflection, achieving specific angular light output profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional rigid lightguides are used in edge-lit configurations, then light flux can be effectively directed, but the device thickness and volume increase significantly
Solution Approach 1:
The patent replaces conventional rigid lightguides with flexible lightguide films that are only 0.5mm thick. These thin film-based lightguides maintain the ability to direct light flux while enabling the device to be much thinner and more flexible, directly resolving the contradiction between light flux delivery and device thickness.
Solution Approach 2:
The patent changes the physical parameters of the lightguide from rigid and thick to flexible and thin (0.5mm). By modifying the material properties and dimensions while maintaining optical functionality through carefully designed light extraction and turning features, the device achieves both sufficient light flux and reduced thickness.
2Volume of moving object
If lightguide thickness is reduced to decrease device volume, then flexibility and thinness improve, but light flux coupling becomes insufficient
Solution Approach 1:
The patent applies local quality by creating specific regions within the thin lightguide film with different optical properties. Light extraction features are positioned at specific locations to frustrate total internal reflection and extract light where needed, while light turning features redirect light at specific angles. This localized optimization ensures sufficient light flux coupling despite the overall thinness of the 0.5mm lightguide.
Solution Approach 2:
The patent uses light turning features as intermediary elements between the light source and the display. These features redirect frustrated totally internally reflected light into specific angular distributions, acting as mediators that ensure adequate light flux is delivered to the display despite the reduced lightguide thickness.
3Illumination intensity
If conventional thick lightguides are used, then sufficient light flux is maintained, but design flexibility and configuration options are limited
Solution Approach 1:
The patent employs flexible thin film lightguides that can be bent, folded, and configured in various shapes. This flexibility enables diverse design configurations and illumination modes that would be impossible with rigid thick lightguides, while the film's optical properties maintain sufficient light flux delivery.
Solution Approach 2:
The patent makes the lightguide structure dynamic and adaptable rather than static and rigid. The thin film construction allows the lightguide to be configured in different geometries and orientations, enabling the device to adapt to various design requirements while maintaining optical performance.
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 enables a thinner, more flexible light emitting device with improved angular light output profiles, reducing volume and enhancing design flexibility while maintaining sufficient light flux.
Implementation Method 1
a light source positioned to emit light that propagates by total internal reflection within the lightguide region
Implementation Method 2
the plurality of light extraction features frustrate totally internally reflected light from the light source propagating between the opposing surfaces of the core layer such that light exits the core layer in the light emitting region into the cladding layer
Implementation Method 3
a light turning film optically coupled to the second side of the cladding layer, the light turning film having a thickness in a thickness direction and comprising a plurality of light turning features with a first light receiving surface and a second light receiving surface, wherein a first portion of the totally internally reflected light frustrated and exited the core layer is redirected by the first light receiving surface
Implementation Method 4
the light diffusely reflecting from a reflective spatial light modulator has a peak luminous intensity within 10 degrees from a direction normal to a surface of the display
Data Source
AI summary
In one embodiment, a display comprises a light source positioned to emit light into a 0.5 millimeter thick lightguide with light extraction features, a cladding layer optically coupled to a core layer of the lightguide on a first side, a light turning film optically coupled to the cladding layer on an opposite side, the light turning film comprising a light turning features that redirect frustrated totally internally reflected light from the core layer into a first portion of light with a first peak luminous intensity at a first angle and a second portion of light with a second peak luminous intensity at a second angle different from the first angle and on an opposite side of the thickness direction, and the light diffusely reflecting from a reflective spatial light modulator has a peak luminous intensity within degrees from a direction normal to a surface of the display.