Integrated Lightguide In-Coupling Optics for Stray-Light Reduction
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Solution Overview
Problem
Conventional light in-coupling structures for lightguides are complicated, difficult to assemble, and result in degraded light extraction efficiency, with issues such as light leakage and stray light due to Fresnel reflections, affecting transparency and contrast in transparent illumination devices.
Innovation Solution
An optical device with a simple structure incorporating optically functional layers, including low-refractive index layers and air cavities, to efficiently guide and extract light using total internal reflection, minimizing light loss and stray light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a separate in-coupling structure with reflector is used to couple light to the lightguide, then light coupling is achieved, but the structure becomes complicated and assembly becomes difficult
Solution Approach 1:
The patent merges the in-coupling structure with the lightguide by integrating optical elements (such as microlenses or prisms) directly into the lightguide body or its adhesive layers, eliminating the need for separate in-coupling components and reflectors. This integration simplifies the overall structure and reduces assembly complexity while maintaining effective light coupling.
2Ease of manufacture
If a separate in-coupling structure is used, then light coupling is achieved, but the final light extraction efficiency is degraded
Solution Approach 1:
By integrating the in-coupling optical elements directly with the lightguide, the patent eliminates additional interfaces between separate components that would cause Fresnel reflections and light loss. The integrated design reduces the number of optical interfaces, thereby minimizing reflection losses and improving overall light extraction efficiency.
Solution Approach 2:
The patent uses the adhesive layer between the lightguide and the optical medium as an intermediary optical element. By controlling the refractive index and optical properties of this adhesive layer, the patent achieves effective light coupling while minimizing reflection losses, thus improving light extraction efficiency compared to traditional separate in-coupling structures.
3Ease of manufacture
If conventional in-coupling structures are used, then light is coupled to the lightguide, but light leakage occurs when the angle of incidence is smaller than the critical angle
Solution Approach 1:
The patent employs the adhesive layer as an intermediary optical element with controlled refractive index properties. This intermediary layer helps control light propagation angles and prevents light leakage by ensuring that light entering the lightguide does so at angles that satisfy total internal reflection conditions, thereby eliminating the harmful light leakage effect.
4Ease of manufacture
If additional optical sheets are inserted to control light distribution, then light distribution is managed, but transparency is compromised
Solution Approach 1:
The patent merges the light distribution control function directly into the lightguide structure through integrated optical elements and surface patterns. This integration eliminates the need for additional separate optical sheets, thereby maintaining the transparency of the overall device while achieving effective light distribution control.
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
Enhances light extraction efficiency, improves transparency, and maintains high contrast by controlling light distribution and reducing stray light, suitable for applications like frontlights, backlights, and signage.
Implementation Method 1
efficiently guide and extract light using total internal reflection, minimizing light loss and stray light
Implementation Method 2
stray light due to Fresnel reflections
Data Source
Figure 1A(a)~1A(b)
Figure 1B
Figure 2A(a)~2A(b)
AI summary
With a simple configuration, an optical device having an in-coupling function to a lightguide is provided. The optical device includes a light guiding layer; and in-coupling optics provided integrally with the light guiding layer to couple light from a light source to an incident edge of the light guiding layer. The in-coupling optics include an optical element that is convex toward the incident edge and an air cavity provided between the optical element and the incident edge.