Optical Device Concave Reflective Portions Light Diffusion
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Solution Overview
Problem
Wide angle lenses in light emitting device packages used in backlight modules of display and lighting devices often result in non-uniform light diffusion, leading to defects in optical uniformity such as mura, and there is a need for thinner backlight modules to accommodate increased application ranges.
Innovation Solution
An optical device with a concave light incident surface and a reflective surface that includes a first reflective portion with a concave surface and a second reflective portion with a flat region, configured to totally reflect light at a predetermined angle between 20 to 40 degrees, enhancing light distribution uniformity and reducing module thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If wide angle lenses are used in light emitting device packages to diffuse light, then light can be diffused from central portion to lateral region, but non-uniform luminance distribution occurs leading to mura defects
Solution Approach 1:
The second surface of the optical device is segmented into multiple reflective portions with different functions: a first reflective portion with a first curvature radius for controlling light reflection angle, and a second reflective portion with a second curvature radius for adjusting luminance distribution. This segmentation allows independent optimization of each region to achieve uniform light diffusion while maintaining wide angle capability.
Solution Approach 2:
Different regions of the optical device are assigned different optical properties: the light incident surface has a first curvature radius for wide angle light entry, while the second surface has varying curvature radii (first and second reflective portions) to control light reflection and distribution locally. This local quality variation ensures uniform luminance distribution across different areas of the device.
2Illumination intensity
If conventional optical devices are used to ensure sufficient light diffusion, then light distribution is achieved, but module thickness cannot be reduced further
Solution Approach 1:
The optical device utilizes curved surfaces throughout its structure: the light incident surface has a first curvature radius, the second surface has a first reflective portion with a first curvature radius and a second reflective portion with a second curvature radius. These curved surfaces enable efficient light manipulation within a compact thickness, achieving sufficient light diffusion without increasing module thickness.
3Loss of energy
If the second surface has a purely concave reflective portion, then light reflection is enhanced, but light extraction efficiency and luminance uniformity are compromised
Solution Approach 1:
The second surface is divided into a first reflective portion and a second reflective portion with different curvature radii. The first reflective portion (with larger curvature radius) controls the reflection angle to enable light extraction, while the second reflective portion (with smaller curvature radius) enhances light reflection efficiency. This segmentation resolves the contradiction between reflection efficiency and light extraction.
Solution Approach 2:
The curvature radius parameter is varied across different regions of the second surface. The first reflective portion has a first curvature radius optimized for light extraction at specific angles, while the second reflective portion has a second curvature radius optimized for enhancing reflection. This parameter variation allows simultaneous optimization of both light extraction efficiency and reflection efficiency.
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 solution improves luminance distribution uniformity and increases external light extraction efficiency, allowing for a thinner optical device and light source module with reduced light loss and enhanced performance.
Implementation Method 1
The first reflective portion is configured to totally reflect light incident at a predetermined angle or more, and the predetermined angle is within a range of 20 degrees to 40 degrees, with respect to a top surface of the light source once to the light exit surface
Implementation Method 2
Wide angle lenses of light emitting device packages, employed as back light modules of display devices or lighting devices, are used to diffuse light, using refraction, from a central portion to a relatively wide lateral region
Implementation Method 3
a second surface disposed opposite the first surface, the second surface being configured to reflect light which is incident on the concave light incident surface
Data Source
AI summary
An optical device is provided. The optical device includes a first surface that defines a concave light incident surface facing a central axis and a light source; a second surface disposed opposite the first surface which is configured to reflect light incident on the concave light incident surface; and an inclined light exit surface between the first surface and the second surface. The second surface includes a concave first reflective portion curving toward the first surface, and a substantially flat second reflective portion which portion is interposed between a first reflective portion edge of the first reflective portion and an outer second surface edge of the second surface. The first reflective portion is configured to totally reflect light incident at a predetermined angle or more with respect to a top surface of the light source once to the light exit surface.