LED Recess Reflector Geometry for Higher Light Extraction
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Solution Overview
Problem
Conventional light-emitting devices have low light extraction efficiency due to the design of the light-reflective member, which reflects a significant portion of emitted light back into the device rather than allowing it to be directly emitted.
Innovation Solution
A light-emitting device with a base member having a recess and a light-reflective member disposed on the upper surface and inner lateral surface of the base member, where the inner lateral surface features a specific geometry with multiple surfaces that allow the light-reflective member to be positioned below the light-emitting element, reducing reflection and enhancing direct light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the light-reflective member is disposed to cover the entire inner lateral surface of the wall portion, then light reflection is enhanced, but light extraction efficiency deteriorates due to reduced direct emission
Solution Approach 1:
The inner lateral surface of the wall portion is segmented into two distinct regions: a first region with a first slope angle (45-60 degrees) that promotes light reflection, and a second region with a second slope angle (15-30 degrees) that facilitates direct light emission. This segmentation allows different portions of the surface to serve different optical functions, resolving the contradiction between maximizing reflection and maintaining direct emission for efficient light extraction.
2Area of stationary object
If the wall portion is made taller to increase reflection area, then light reflection is improved, but the distance between the light-reflective member and light-emitting element increases, reducing direct emission
Solution Approach 1:
Instead of using a single vertical or uniformly sloped wall portion, the design employs a curved or multi-segmented profile with varying slope angles. The wall portion transitions from a steeper first slope to a gentler second slope, creating a smooth optical path that allows light to escape directly while still providing sufficient reflective surface area. This curved geometry resolves the contradiction by maintaining proximity to the light-emitting element while maximizing reflective area.
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 significantly improves light extraction efficiency by allowing a larger proportion of emitted light to be directly emitted from the device, rather than being reflected back, thereby enhancing the overall performance of the light-emitting device.
Implementation Method 1
a light-reflective member that reflects light from the light-emitting element inside a base member having a recess
Data Source
AI summary
A light-emitting device includes a base member having a recess inside which a light-emitting element is disposed; and a light-reflective member continuously disposed on an upper surface of the bottom portion and at least a portion of an inner lateral surface of a wall portion inside the recess of the base member, in a cross-sectional view, the inner lateral surface of the wall portion having a first surface, a second surface located above the first surface, and a third surface connecting the first surface and the second surface, a shortest distance between the second surface and the light-emitting element being larger than a shortest distance between the first surface and the light-emitting element, the third surface being located below an upper surface of the light-emitting element, and an upper end of the light-reflective member being located below an upper surface of the wall portion.