Light Source Unit Polarizer with Recessed Protruding Structure
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Solution Overview
Problem
Existing light source units with LEDs and polarizers suffer from light leakage through side surfaces, resulting in reduced light intensity and inefficient utilization, especially when a quarter wave plate is used, which also faces heat resistance issues due to its thickness.
Innovation Solution
A light source unit with a polarizer having a recessed and protruding structure that varies its transmission axis direction, combined with a diffraction grating, effectively transmits TM polarized light and diffracts TE polarized light, reducing side leakage and increasing output intensity, while maintaining high heat resistance with a thinner design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a quarter wave plate is provided between the LED and the polarizer to convert TE waves into TM waves, then the intensity of outgoing light can be increased, but the device complexity and heat resistance issues increase due to the thickness requirement
Solution Approach 1:
The patent extracts the polarization conversion function from a separate quarter wave plate component and integrates it directly into the polarizer structure through recessed and protruding patterns. This eliminates the need for a distinct quarter wave plate while maintaining the TE-to-TM wave conversion capability, thereby reducing device complexity while preserving light intensity enhancement
Solution Approach 2:
The patent merges the quarter wave plate's polarization conversion function with the polarizer's light transmission function into a single integrated component. The recessed and protruding patterns on the polarizer surface combine wave conversion and polarization filtering in one element, simplifying the overall device structure while achieving the same optical effect
2Reliability
If a thick quarter wave plate is used to ensure heat resistance, then reliability under thermal stress is improved, but the distance between the LED and polarizer increases, causing light leakage through side surfaces
Solution Approach 1:
The patent uses a thin film structure with recessed and protruding patterns instead of a thick quarter wave plate. This thin film approach maintains adequate heat resistance while minimizing the distance between LED and polarizer, thereby preventing light leakage through side surfaces and improving energy efficiency
Solution Approach 2:
The patent changes the structural parameters of the polarizer by adding recessed and protruding patterns, which enable the thin film to achieve the polarization conversion function previously requiring a thick quarter wave plate. This parameter change allows maintaining heat resistance while reducing thickness to prevent light leakage
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 enhances light intensity by converting TE waves into TM waves, reducing side leakage, and maintaining high heat resistance, thus improving the efficiency and performance of the light source unit compared to traditional configurations.
Implementation Method 1
Polarizer 101 includes a transmission axis, and transmits light with a polarization component parallel to the transmission axis, while reflecting light with a polarization component orthogonal to the transmission axis
Implementation Method 2
the polarizer includes a recessed and protruding structure which transmits, of light that exits from the emission surface and that travels from the light emitting element side into the polarizer, a portion of the light whose polarization direction is parallel to the transmission axis, while reflecting and diffracting a portion of the light whose polarization direction is orthogonal to the transmission axis
Implementation Method 3
The emission surface of LED 100 specularly reflects the TE wave from polarizer 101. The reflected light travels toward polarizer 101. With regard to the specular reflection of the TE wave by the emission surface, the incident light and the reflected light have the same direction of polarization
Data Source
AI summary
A light source unit includes LED 1 with an emission surface and polarizer 2 that is positioned opposite the emission surface of LED 1 and in which the direction of a transmission axis varies depending on a position in the plane of polarizer 2. Polarizer 2 includes a recessed and protruding structure which transmits, from among light that travels from LED 1 side into polarizer 2, a portion of the light whose polarization direction is parallel to the transmission axis, while reflecting and diffracting a portion of the light whose polarization direction is orthogonal to the transmission axis. The recessed and protruding structure includes diffraction grating 3.