Projection Display Antireflection Layer Ghost Light Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Projection display devices that use a common part of the image-forming optical system for both projection and imaging suffer from ghost light reflection, leading to degraded imaging quality due to high-brightness ghost light forming double images on the imaging element.
Innovation Solution
A projection display device design that includes a first optical system used in common for projection and imaging, with antireflection target surfaces treated with an antireflection layer to minimize ghost light interference, and a separation member to separate optical paths, ensuring that surfaces satisfying specific conditional expressions are set as antireflection targets to reduce ghost light impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common part of the image-forming optical system is used for both projection and imaging, then device complexity is reduced, but imaging quality deteriorates due to ghost light reflection
Solution Approach 1:
A separation member is introduced as an intermediary component to divide the optical path between projection and imaging functions. This member selectively transmits imaging light while reflecting projection light, thereby preventing ghost light from reaching the imaging element while maintaining the dual-function optical system
Solution Approach 2:
Antireflection layers are selectively applied to specific lens surfaces where ghost light reflection is most problematic. By treating only certain surfaces (those satisfying specific conditional expressions) rather than all surfaces, the solution locally addresses the ghost light issue while minimizing impact on overall optical performance
2Object-affected harmful factors
If antireflection layers are applied to lens surfaces, then ghost light is suppressed, but manufacturing complexity increases
Solution Approach 1:
Instead of applying antireflection layers to all lens surfaces, the invention identifies specific surfaces satisfying conditional expressions (0 ≤ BETn/BET ≤ 0.125 and |(In−I)×BETn/f|×100 ≤ 5) and applies treatment only to those. This localized approach reduces manufacturing complexity compared to universal treatment while still effectively suppressing ghost light
Solution Approach 2:
The invention uses specific parameters (BETn/BET ratio and |(In−I)×BETn/f|×100 value) to identify which lens surfaces require antireflection treatment. By changing the selection criterion from general to parameter-based, the manufacturing process becomes more precise and manageable
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 ghost light interference, maintaining high imaging quality by reducing the brightness of ghost light and preventing double image formation, while optimizing the number of lenses for both projection and imaging performance.
Implementation Method 1
at least one of the antireflection target surfaces includes an antireflection layer
Data Source
AI summary
The projection display device includes an imaging element, a light valve, and an image-forming optical system that projects an optical image according to light emitted from the light valve onto a magnification side imaging surface and forms an image of light incident from a magnification side on an imaging element. The image-forming optical system includes a first optical system that comprises at least one lens and is used in common in projection and imaging, and a separation member that separates an optical path from the light valve toward the first optical system from an optical path from the first optical system toward the imaging element. An antireflection layer is comprised in at least one of antireflection target surfaces having a significant influence of ghost light.