Light Guide Plate with Dual-Sided Emission and Rear Surface Light Management
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Solution Overview
Problem
Fresnel reflections at the emission surface of a transparent light guide plate cause light to leak from the rear surface, leading to unintended visibility of patterns or images from the opposite side, compromising the intended display.
Innovation Solution
The optical device employs a light guide plate with distinct regions for light emission, where the second emission part on the rear surface has a lower luminous flux and pattern density, and is designed to emit light that is complementary or white, reducing the visibility of leaked light and creating a blurrier image compared to the primary emission surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a transparent light guide plate is used to guide light, then light can exit from the emission surface, but light leaks from the rear surface due to Fresnel reflections, causing unintended visibility of patterns
Solution Approach 1:
The patent converts the harmful Fresnel reflections that cause light leakage into a beneficial effect by intentionally designing reflective dots on the rear surface. These reflective dots capture the leaked light and redirect it toward the emission surface, transforming the harmful leakage into useful light output while preventing unwanted pattern visibility from the rear.
Solution Approach 2:
The patent applies different optical properties to different regions of the light guide plate. The rear surface has reflective dots with specific reflectivity characteristics, while the emission surface has extraction structures. This local differentiation allows the rear surface to manage leaked light constructively without compromising the overall light guiding function.
2Illumination intensity
If optical surfaces are formed on the rear surface to extract light, then light can exit from both emission surfaces, but pattern visibility from the rear surface increases due to leaked light
Solution Approach 1:
The reflective dots on the rear surface convert the harmful leaked light into a beneficial resource. By reflecting this leaked light toward the emission surface, the system maintains brightness while preventing the leaked light from forming visible patterns on the rear side, thus preserving information integrity.
Solution Approach 2:
The patent changes the optical parameters of the rear surface by introducing reflective dots with specific reflectivity and spatial distribution. This parameter modification allows the rear surface to function as both a light extraction surface and a light management surface, controlling where and how light exits while preventing unwanted pattern formation.
3Adaptability or versatility
If the light guide plate allows light to pass through to the rear surface, then dual-sided emission is achieved, but the image quality deteriorates due to blur from the rear emission
Solution Approach 1:
The patent creates local quality differences between the two emission surfaces. The front emission surface maintains high image sharpness for primary display, while the rear emission surface provides softer, blurrier light for ambient illumination or secondary display purposes. This local differentiation allows dual-sided emission with differentiated image quality characteristics.
Solution Approach 2:
The rear surface optical structures are designed to provide partial light extraction rather than full extraction. This partial action ensures that the rear surface contributes to overall brightness and dual-sided emission capability while maintaining the primary image sharpness from the front surface, as the rear emission is intentionally subdued.
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 configuration minimizes the visibility of leaked light, making the intended image less conspicuous from the rear side while maintaining a clear and focused image on the emission surface, thus addressing the issue of unwanted light leakage and pattern visibility.
Implementation Method 1
a plurality of optical surfaces whereon light guided by the light guide plate is incident, the optical surfaces causing the light incident thereon to exit from the first emission surface and a second emission surface opposite the first emission surface
Implementation Method 2
Fresnel reflections at the emission surface of a transparent light guide plate causes some light that should exit from the emission surface to also leak from the rear surface opposite the emission surface
Data Source
AI summary
An optical device includes: a light guide plate; a first light emission part provided in a first region of the light guide plate, the first light emission part having optical surfaces that cause the light incident thereon to exit from a first emission surface and a second emission surface opposite the first emission surface; and a second light emission part provided in a second region of the light guide plate, the second light emission part having optical surfaces that cause the light incident thereon to exit from the first emission surface and the second emission surface. The optical device configured to control the luminous flux from the first and second emission surfaces via the optical surfaces in the first and second light emission parts to thereby control how leaked light is perceived by an observer on the opposite side of the emission surface of the light guide plate.