Light Guide Plate Metal Reflective Layer Color Uniformity
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Solution Overview
Problem
Optical glass light guide plates in back light modules absorb short-wavelength light, leading to uneven light colors as the distance from the light source increases, due to higher absorptivity for shorter wavelengths.
Innovation Solution
A light guide plate with a metal reflective layer coated on its bottom surface, where the metal reflective layer has a higher reflectance for short-wavelength light, compensating for the absorption and ensuring more uniform light emission by reflecting absorbed blue light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light guide plate made of optical glass material is used, then the light guide plate can effectively guide light, but the short-wavelength light is absorbed more, leading to uneven light colors
Solution Approach 1:
The patent applies the principle of converting harm into benefit by using a metal reflective layer to reflect the short-wavelength light that would otherwise be absorbed by the optical glass. The metal layer, positioned at the bottom of the light guide plate, reflects blue light (400-500nm) back into the optical path, converting the harmful absorption effect into a beneficial enhancement of short-wavelength light output, thereby improving overall light color uniformity
Solution Approach 2:
The patent employs composite materials by combining optical glass with a metal reflective layer. This composite structure allows the optical glass to maintain its light guiding properties while the metal layer compensates for the short-wavelength absorption deficiency, creating a hybrid system that overcomes the limitations of pure optical glass material
2Area of stationary object
If the distance between the exit surface and light source increases, then more light can be distributed, but the short-wavelength light quantity decreases due to absorption
Solution Approach 1:
The metal reflective layer converts the harmful absorption of short-wavelength light during long-distance propagation into a beneficial effect by reflecting blue light back into the optical path, maintaining short-wavelength light intensity even at greater distances from the light source
3Illumination intensity
If a metal reflective layer with higher reflectance for short-wavelength light is added, then light color uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by adding the metal reflective layer only at the bottom surface of the light guide plate, rather than throughout the entire structure. This localized modification targets the specific problem of short-wavelength absorption at the light guide plate's exit surface, improving light color uniformity without unnecessarily increasing overall device complexity
Solution Approach 2:
The composite structure of optical glass combined with a thin metal reflective layer achieves improved light color uniformity while maintaining relatively simple device architecture, as the metal layer can be applied as a thin coating rather than a bulky additional component
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 metal reflective layer improves light color uniformity by increasing reflectance for shorter wavelengths, thereby reducing color unevenness and enhancing output efficiency of the light guide plate.
Implementation Method 1
an average reflectance of the metal reflective layer for the light in the wavelength range of 400 to 550 nanometers is greater than an average reflectance of the metal reflective layer for the light in the wavelength range of 550 to 700 nanometers
Data Source
AI summary
A light guide plate includes a light guide layer and a metal reflective layer. The light guide layer has a light emitting surface, a bottom surface and a light incident surface. The light incident surface is located between the light emitting surface and the bottom surface. The metal reflective layer is coated on the bottom surface of the light guide layer. Additionally, an average reflectance of the metal reflective layer for light in a wavelength range of 400 to 550 nanometers is greater than an average reflectance of the metal reflective layer for light in a wavelength range of 550 to 700 nanometers.