Three-Panel DMD Projection Optics with Unpolarized Dichroic Mirrors
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Solution Overview
Problem
Existing projection display systems face challenges in achieving high brightness with a compact form factor and reduced production costs, as conventional three-panel micro-mirror projection systems are large and inefficient in utilizing unpolarized light.
Innovation Solution
A compact optical apparatus using a cross-prism with dichroic mirrors to split and integrate light beams, combined with unpolarized dichroic mirrors and TIR prisms to enhance brightness and reduce size, and incorporating white LEDs or laser light sources to minimize production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional three-panel micro-mirror projection system is used to achieve high brightness, then the optical output brightness is improved, but the system size becomes as large as a large refrigerator
Solution Approach 1:
The patent combines three separate DMD panels and their associated optical paths into a single integrated projection system. The three DMD panels (red, green, blue) are positioned adjacent to each other and share common optical components including a single projection lens and integrated light source system, merging what would traditionally be three separate projection systems into one compact unit.
Solution Approach 2:
The projection lens serves multiple functions by receiving and projecting light from all three DMD panels simultaneously. The light source system provides illumination for all three panels, and the optical path integrates multiple color channels through a unified optical train, making each component perform multiple functions rather than requiring dedicated components for each color channel.
2Ease of operation
If conventional polarized light cross-prisms are used in three-panel LCD and LCOS systems, then light beam splitting and integration is achieved, but brightness is reduced because half of unpolarized light is not utilized
Solution Approach 1:
The patent changes the polarization parameter of the dichroic mirrors from polarized to unpolarized. Instead of using conventional polarized light cross-prisms that only transmit one polarization state, the invention employs dichroic mirrors that reflect or transmit light regardless of polarization direction, thereby utilizing 100% of the unpolarized light from the LED source rather than losing half of it.
3Illumination intensity
If conventional projection systems are designed for high brightness output, then illumination intensity is improved, but production cost and manufacturing complexity increase
Solution Approach 1:
The patent replaces expensive conventional light sources (such as UHP lamps and color wheels) with inexpensive white LED modules. The LED-based light source system is significantly cheaper to manufacture and has a longer operational life, reducing both initial production costs and maintenance expenses while maintaining or improving brightness output.
Solution Approach 2:
The projection system is divided into three independent but adjacent DMD panels (red, green, blue) that can be manufactured and assembled separately. This modular segmentation allows for simplified manufacturing, testing, and replacement of individual components without affecting the entire system, thereby reducing production complexity and cost.
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 system achieves 2-3 times brighter optical output with a significantly smaller size and reduced production costs compared to conventional systems, while minimizing unwanted reflections and maximizing light utilization.
Implementation Method 1
a cross-prism (105) having dichroic mirrors (106 and 107) inside and the white light is split into 3 color beams
Implementation Method 2
a TIR (total internal reflection) prism allowing vertical incident light even the mirror tilt angle is 45 degrees
Implementation Method 3
provide a dichroic cross prism for unpolarized light, which passes or reflects light regardless of the direction of polarization
Data Source
AI summary
Optics for Projection Display are disclosed including 3 DMD panel system enabling a compact size operable with a white light source such as a UHP lamp or white LED.