LED Illumination Device Uniform Polarized Light
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Solution Overview
Problem
LEDs emit light that is not polarized and uniform enough to be directly applicable for displays in projection and direct viewing systems, which require polarized light for high-resolution imaging.
Innovation Solution
An LED illumination device comprising a light guiding member, an LED with a reflective substrate, a reflective polarizer, and a quarter-wave retarder, which together uniformize and polarize the light emitted by the LED, ensuring it meets the polarization requirements for displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LED is used for illumination, then power consumption is reduced and lifespan is extended, but the emitted light is not polarized and uniform enough for display applications
Solution Approach 1:
A light guiding member is introduced as an intermediary component between the LED and the display. This light guiding member transforms the non-polarized, non-uniform LED light into uniformly polarized light through its internal structure design, enabling LED illumination to meet display requirements while maintaining LED advantages of low power consumption and long lifespan
2Device complexity
If LED light is used directly for display illumination, then device complexity is reduced, but the light polarization state is insufficient for high-resolution imaging
Solution Approach 1:
The light guiding member incorporates local quality variations through its internal structure design, including regions with different optical properties to achieve uniform polarization across the entire light output. This allows the system to maintain relatively simple overall structure while achieving high polarization uniformity through localized structural optimization
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 device effectively produces uniformly polarized light, enhancing the suitability of LED illumination for projection and direct viewing systems by improving light utilization and reducing manufacturing costs.
Implementation Method 1
The light guiding member includes a light input surface and an opposite light output surface. The light guiding member tapers along a direction oriented from light output surface to the light input surface, and is configured to uniformize light entered therein and output the uniformized light through the light output surface.
Implementation Method 2
The reflective polarizer allows the light of the first polarization state to pass therethrough and reflects the light of the second polarization state back into the light guiding member through the second end surface.
Implementation Method 3
The quarter-wave retarder is provided between the LED and the reflective polarizer. The reflective substrate of the LED is configured to reflect the light from the LED of the second polarization state reflected by the reflective polarizer so as to make the second polarization state convert into the first polarization state after the light passes through the quarter-wave retarder a plurality of times.
Data Source
AI summary
A LED illumination device includes a tapered light guiding member, a LED, a reflective polarizer and a quarter-wave retarder. The light guiding member includes a light input surface and an opposite light output surface. The LED includes a LED chip and a reflective substrate on which the LED chip is mounted. The LED chip faces toward the light input surface. The reflective polarizer faces toward the light output surface, and allows a first polarization light to pass therethrough and reflects a second polarization light back into the light guiding member. The quarter-wave retarder is provided between the LED and the reflective polarizer. The reflective substrate reflects the second polarization light reflected by the reflective polarizer so as to make the second polarization light convert into the first polarization light after the light passes through the quarter-wave retarder a plurality of times.