Projection Display Optical System Light Leakage Control
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Solution Overview
Problem
Existing projection display devices suffer from light leakage from the light valve to the imaging element, leading to deterioration of imaging quality due to high brightness projection light, resulting in ghosting in captured images.
Innovation Solution
A projection display device is designed with a multi-optical system configuration that includes a first optical system for common use in projection and imaging, a second optical system used only in projection, and a third optical system used only in imaging, employing a separation member and polarizers to minimize light leakage, with a quarter wave plate and polarizer arrangement to reduce reflected light and an adjustment mechanism for precise polarizer axis control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a separation member is used to separate optical paths in a projection display device, then projection and imaging functions can be shared, but light leakage from the light valve to the imaging element occurs causing ghosting in captured images
Solution Approach 1:
The optical system is divided into three separate optical systems: a first optical system for common projection and imaging functions, a second optical system for projection only, and a third optical system for imaging only. This segmentation allows each subsystem to be optimized independently, with the first optical system equipped with polarizers and quarter wave plates to prevent light leakage while maintaining dual functionality.
Solution Approach 2:
Polarizers and quarter wave plates are introduced as intermediary optical elements in the first optical system. These components act as mediators to control the polarization state of light, allowing the system to distinguish between projection light (which should be blocked) and imaging light (which should pass through), thereby preventing light leakage without compromising the shared optical path.
2Object-affected harmful factors
If multiple optical systems are used to prevent light leakage, then imaging quality improves, but device complexity increases
Solution Approach 1:
The first optical system is designed to serve multiple functions: it handles both projection and imaging operations, and incorporates polarization control elements that work for both functions. This multi-functionality reduces the need for completely separate optical paths while still achieving effective light leakage prevention through intelligent use of polarizers and quarter wave plates.
Solution Approach 2:
The system utilizes changes in polarization parameters to control light path separation. By adjusting the polarization state of light using quarter wave plates and polarizers, the system can dynamically control which light paths are active or blocked, achieving effective separation without requiring physically separate optical components for each function.
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 effectively suppresses light leakage and ghosting, maintaining high projection and imaging performance while reducing the number of lenses and reflective surfaces, thereby enhancing imaging quality and device installability.
Implementation Method 1
a light valve that emits an optical image based on image data in a prescribed polarization state, and an imaging optical system that projects an optical image of light emitted from the light valve
Implementation Method 2
the first optical system comprises, in order from the magnification side, a quarter wave plate and a polarizer arranged in a state of transmitting the light emitted from the light valve
Implementation Method 3
a polarizer arranged in a state of shielding the light emitted from the light valve
Implementation Method 4
a separation member that separates an optical path from the second optical system toward the first optical system from an optical path from the first optical system toward the third optical system, and the first optical system comprises, in order from the magnification side, a quarter wave plate and a polarizer
Data Source
AI summary
A projection display device includes an imaging element, a light source, a light valve that modulates light from the light source and emits modulated light in a prescribed polarization state, and an imaging optical system. The imaging optical system includes a first optical system that is used in common in projection and imaging, a second optical system that is used only in projection, a third optical system that is used only in imaging, and a separation member that separates an optical path from the second optical system toward the first optical system from an optical path from the first optical system toward the third optical system. The first optical system comprises a quarter wave plate and a polarizer arranged in a state of transmitting the light emitted from the light valve.