Dual-Lamp Illumination Optical System for Projectors
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Solution Overview
Problem
Existing illumination optical systems for DLP projectors are inefficient in utilizing polarized light, leading to light loss and poor projection quality, especially when trying to project onto large screens, as they either lack mechanisms for combining light beams from two lamps or effective polarization conversion.
Innovation Solution
A compact illumination optical system that uses a first and second light source, a light condensing optical system, a polarization separation optical system, a ½ phase difference plate, and a rod integrator to efficiently combine and convert polarized light beams, ensuring uniform energy distribution and effective polarization conversion for bright and high-quality projections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If polarization conversion is performed at an entrance face of a rod integrator by displacing imaging positions of light beams on a polarization-by-polarization basis, then light utilization efficiency is improved, but the projection image brightness is insufficient because no mechanism for combining light beams from two-lamp sources is adopted
Solution Approach 1:
The patent combines light beams from two separate lamp sources by making them form images at the same position on the rod integrator entrance face. The first light source forms an image at a first position and the second light source forms an image at a second position, where both positions correspond to the same physical location on the rod integrator entrance face, thereby merging the light beams to increase overall brightness while maintaining polarization conversion efficiency.
Solution Approach 2:
The patent segments the illumination system into two separate light source paths, each with its own imaging position on the rod integrator entrance face. By dividing the light source into two separate sources with distinct imaging positions that converge at the same location, the system achieves both efficient polarization conversion and increased brightness through combination.
2Illumination intensity
If light beams from two lamps are combined by making light beams from the two-lamp sources form images at the same position, then brightness is improved, but effective polarization conversion cannot be performed
Solution Approach 1:
The patent applies different imaging positions for different light sources at the same physical location on the rod integrator entrance face. The first light source is imaged at a first position and the second light source is imaged at a second position, where both positions correspond to the same location but with distinct local imaging characteristics. This local differentiation enables polarization conversion while maintaining combined brightness.
3Loss of energy
If light beams from two lamps are combined by making light beams from the two-lamp sources form images at different positions in an entrance face of a rod integrator, then polarization conversion can be performed, but effective projection cannot be performed by making use of polarization
Solution Approach 1:
The patent creates image copies of both light sources at corresponding positions on the rod integrator entrance face. The first light source forms an image at a first position and the second light source forms an image at a second position, where both images are formed at the same physical location. This copying approach allows polarization conversion to occur effectively while maintaining the reliability needed for projection.
4Adaptability or versatility
If a lens array is used as an integrator to perform both combining of light beams from two lamps and polarization conversion, then both functions are achieved, but illumination light beams from lenses of the lens array are liable to be displaced from each other on a display device, generating ghost light and degrading projection quality
Solution Approach 1:
The patent extracts the polarization conversion function from the integration process by using a rod integrator instead of a lens array. The rod integrator handles light beam combination while a separate ½ wavelength plate performs polarization conversion. This separation eliminates the ghost light problem caused by lens array displacement while maintaining dual functionality.
Solution Approach 2:
The patent introduces a ½ wavelength plate as an intermediary component between the rod integrator and the display device. This intermediary performs polarization conversion after the rod integrator combines the light beams from both sources, ensuring that the polarization conversion occurs on already-combined light without causing beam displacement or ghost light artifacts.
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 highly-efficient, high-quality bright illumination and projection by effectively combining and converting polarized light beams from two lamps, allowing for bright and clear projection images even on large screens without significant light loss.
Implementation Method 1
a light condensing optical system that condenses the first light beam and the second light beam
Implementation Method 2
a polarization separation optical system that separates each of the first light beam and the second light beam into a first polarization component and a second polarization component
Implementation Method 3
a ½ phase difference plate that converts a polarization state of the first polarization component to a polarization state equal to a polarization state of the second polarization component
Implementation Method 4
a rod integrator that uniformizes spatial energy distribution of the first light beam and the second light beam that have undergone condensation
Data Source
AI summary
First and second light sources emit first and second light beams, respectively. A light condensing system condenses the beams, and a polarization separation system separates each of the beams into first and second polarization components. A ½ phase plate converts the polarization state of the first polarization component to one equal to that of the second polarization component, and a rod integrator uniformizes spatial energy distribution of the beams condensed by the light condensing system. A relay system forms an image of an exit face of the rod integrator on a region to be illuminated. The light condensing system condenses the first and second polarization components onto first and second regions, respectively, of an entrance face of the rod integrator; and the ½ phase plate is placed at the first region of the entrance face of the rod integrator or at a position conjugate with the first region.