Secondary Reflector for LED Optical Efficiency
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Solution Overview
Problem
Solid-state lighting systems, such as LED lamps, face inefficiencies due to stray light escaping from total internal reflection (TIR) optical elements, which can be improved by capturing and reusing this light with a highly reflective secondary reflector.
Innovation Solution
A highly reflective secondary reflector, made of materials like microcellular polyethylene terephthalate or polycarbide resin, is positioned adjacent to but spaced apart from the TIR optical element to recapture stray light, enhancing the optical efficiency and mimicking the light pattern of traditional halogen and incandescent bulbs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a TIR optical element is used to concentrate light, then light directionality is improved, but some stray light escapes through the internally reflective surfaces
Solution Approach 1:
A secondary reflector is introduced as an intermediary component between the TIR optical element and the surrounding environment. This secondary reflector captures stray light that escapes from the TIR element's internally reflective surfaces and redirects it back toward the desired direction, thereby reducing energy loss while maintaining the light-concentrating function of the TIR element.
Solution Approach 2:
The invention recovers stray light that would otherwise be lost from the TIR optical element. By positioning a secondary reflector to intercept this escaped light and redirect it back into the optical system, the design recovers energy that would have been wasted, improving overall optical efficiency.
2Loss of energy
If a secondary reflector is placed adjacent to the TIR optical element, then stray light is recaptured, but device complexity increases
Solution Approach 1:
The secondary reflector is designed to work in conjunction with the TIR optical element as an integrated optical system. Rather than treating them as separate, independent components, the design merges their functions where the TIR element provides primary light concentration and the secondary reflector supplements it by capturing escaped light, creating a unified optical arrangement.
Solution Approach 2:
The secondary reflector serves multiple functions: it recaptures stray light, redirects it back into the optical system, and works with the TIR element to achieve both light concentration and stray light management in a single component design.
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 optical arrangement improves the overall efficiency of the LED lamp by recapturing stray light, increasing the total optical efficiency from 80% to 93.6% and mimicking the light pattern of traditional bulbs, providing a more directional and controlled beam.
Implementation Method 1
TIR optical element, which internally reflects light from their curved surfaces to concentrate light
Implementation Method 2
a highly reflective secondary reflector is located adjacent to but not in contact with a total internal reflection (TIR) optical element... This reflector presents a white, diffuse reflective surface to light escaping from the curved surface
Data Source
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AI summary
An optical arrangement for a solid-state lamp is disclosed. A highly reflective secondary reflector is located adjacent to but not in contact with an optical element. In some embodiments, the reflector presents a white, diffuse reflective surface. A secondary reflector with a specular reflective surface can also be used. The secondary reflector can be made of various commercially available materials; for example, MCPET or polycarbide resin, and the arrangement can be used with an LED light source. In some example embodiments, the optical element and the highly reflective secondary reflector each have a plurality of lobes and the arrangement is suitable for an MR16 halogen lamp replacement. In other example embodiments, the highly reflective secondary reflector includes a plurality of recesses corresponding to a plurality of optical elements, and the arrangement is suitable for a PAR incandescent bulb replacement.