Laser Backlight Light Guide Layout for Uniform Display Brightness
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Solution Overview
Problem
Existing laser backlights face challenges in achieving uniform in-plane luminance distribution and efficient light extraction, leading to reduced brightness in display devices.
Innovation Solution
The use of a first light guide with a trapezoidal cross-section and a second light guide with a complementary trapezoidal shape, combined with laser light sources, to enhance light reflection and mixing, resulting in improved light extraction efficiency and uniform luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional light guide structure is used, then the device complexity is low, but the light extraction efficiency is insufficient leading to reduced brightness
Solution Approach 1:
The light guide is divided into multiple segments with different cross-sectional shapes along the light propagation direction. Specifically, a first light guide portion has a first trapezoidal cross-section while a second light guide portion has a second trapezoidal cross-section, allowing each segment to contribute differently to light extraction and propagation efficiency
Solution Approach 2:
The patent employs asymmetric trapezoidal cross-sections where the longer base of the first trapezoid faces the shorter base of the second trapezoid. This asymmetric configuration optimizes the reflection and extraction of laser light at different positions along the propagation path, improving overall light extraction efficiency
2Illumination intensity
If laser light sources are used, then the brightness potential is high, but the in-plane luminance distribution is non-uniform
Solution Approach 1:
Different portions of the light guide are given different cross-sectional characteristics to address local luminance needs. The first trapezoidal portion with its specific orientation handles light extraction in certain regions, while the second trapezoidal portion addresses other regions, creating a more uniform overall luminance distribution across the display panel
Solution Approach 2:
The patent introduces dimensional variation by changing the cross-sectional shape of the light guide along the propagation direction. By transitioning from one trapezoidal cross-section to another with different orientation, the system controls light extraction in the transverse dimension while maintaining propagation in the longitudinal dimension
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 enhances light extraction efficiency and brightness in display devices by ensuring uniform luminescence and reducing light loss, thereby improving display quality.
Implementation Method 1
light emitted from the plurality of light source elements enters the first light guide from the first surface, is totally reflected by the second surface and enters the second light guide, and the light entering the second light guide is totally reflected by the fourth surface
Data Source
AI summary
According to an embodiment, an illumination device includes a first light guide having a cross-sectional shape of a first trapezoidal shape in which a lower side is shorter than an upper side, a second light guide having a cross-sectional shape of a second trapezoidal shape in which a lower side is longer than an upper side, and a plurality of light source elements, and light emitted from the light source elements enters the first light guide from the first surface, is totally reflected at the second surface and enters the second light guide, and the light entering the second light guide is totally reflected at the fourth surface.