Film-Based Lightguide With Folded Coupling Array
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Solution Overview
Problem
Conventional edge-lit configurations for area light emitting devices are limited by thick lightguides, which restrict design flexibility, production methods, and illumination modes, and struggle to efficiently couple light into thinner lightguides, thereby limiting the size and design of displays.
Innovation Solution
A reflective display with a frontlight featuring a thin film lightguide (≤0.5 mm thickness) with an array of coupling lightguides folded to form a stacked input surface, where light from a light source propagates through the coupling lightguides and combines within the lightguide, using light extraction features to direct light towards a reflective spatial light modulator, and a cladding region for optical coupling and light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thick lightguides (2 mm and larger) are used in conventional edge-lit configurations, then light coupling and propagation are improved, but device thickness and volume increase, limiting design flexibility
Solution Approach 1:
The patent transitions from conventional edge-lit configurations to front-lit configurations, fundamentally changing the light injection dimension. Multiple light sources are positioned at the front surface of the lightguide, injecting light directly into the lightguide body rather than from the edge, thereby achieving effective light coupling without requiring thick lightguide structures
Solution Approach 2:
The patent employs thin film lightguides with thicknesses of 0.1 mm to 1 mm, replacing the conventional thick rigid lightguide structures. These thin film lightguides maintain effective light propagation while enabling flexible device designs and reduced overall thickness, directly addressing the volume reduction goal
2Volume of moving object
If thin lightguides are used to reduce device thickness, then device volume is reduced, but light coupling efficiency deteriorates
Solution Approach 1:
By positioning multiple light sources at the front surface and injecting light directly into the lightguide body, the patent achieves effective light coupling in thin film lightguides without relying on edge coupling mechanisms that are ineffective in sub-1mm thickness structures
Solution Approach 2:
The patent modifies key optical parameters including using light sources with specific emission characteristics (LEDs, OLEDs, LCDs) and adjusting lightguide optical properties (refractive index, absorption coefficient) to optimize light coupling efficiency in thin film configurations, enabling effective operation at 0.1 mm to 1 mm thickness
3Stability of the object's composition
If rigid frames are used to house light emitting devices, then structural stability is improved, but design flexibility and adaptability are reduced
Solution Approach 1:
The patent replaces rigid frame structures with flexible thin film lightguide assemblies that can be conformally mounted to various surfaces including curved and irregular geometries. The thin film lightguides maintain structural integrity while enabling adaptable design configurations for different display sizes and shapes
Solution Approach 2:
The front-lit lightguide configuration with multiple light sources can be adapted to various display types (LCDs, OLEDs, reflective displays) and form factors, providing a universal lighting solution that maintains structural stability while offering design flexibility across different applications
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 solution enables thinner, more flexible, and efficient light emitting devices with improved light distribution, allowing for larger display sizes and varied design configurations while maintaining effective light extraction and internal reflection within the lightguide.
Implementation Method 1
light from each coupling lightguide combining and totally internally reflecting within the lightguide region
Implementation Method 2
A plurality of light extraction features frustrate totally internally reflected light within the lightguide region such that the light exits the lightguide
Data Source
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AI summary
A reflective display includes a reflective spatial light modulator and a frontlight. The frontlight includes a lightguide formed from a film. The lightguide includes an array of coupling lightguides continuous with a lightguide region of the lightguide. One or more light sources emit light into the array of coupling lightguides. Light from each coupling lightguide combines and totally internally reflects within the lightguide region. Light extraction features frustrate totally internally reflect light within the lightguide region such that the light exits the lightguide toward the reflective spatial light modulator in a light emitting region of the film. A cladding region is optically coupled to the lightguide so light from the light source propagates into the cladding region. A light extracting region is operatively coupled to the cladding region opposite the lightguide, and light in the cladding region is extracted. A method of producing a display is also disclosed.