Projection Display Ghost Image Prevention via Phase Correction
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Solution Overview
Problem
Existing reflective liquid crystal projectors face challenges in preventing ghost images when projecting three-dimensional content, as the configuration for splitting images into multiple parts complicates the removal of ghost images using traditional quarter-wave plate technologies.
Innovation Solution
A projection display apparatus is designed with a light source, reflective liquid crystal devices, a quarter-wave plate, imaging lenses, and a phase difference corrector to split images into multiple parts and correct the phase difference between p-polarized and s-polarized light, preventing ghost images from forming by ensuring light does not reflect back to the liquid crystal devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a quarter-wave plate is arranged immediately in front of the projection lens to remove ghost images, then ghost image removal is achieved, but the configuration cannot accommodate image splitting into two or more images for 3D cinema
Solution Approach 1:
The patent divides the optical system into separate functional modules: a first optical system for forming the real image and a second optical system for splitting the image. The quarter-wave plate is positioned in the first optical system before the image splitting occurs, allowing ghost image removal without interfering with the 3D image splitting capability. This segmentation enables both functions to operate independently and effectively.
Solution Approach 2:
The patent introduces a polarizing beam splitter as an intermediary element between the quarter-wave plate and the projection lens. This intermediary allows the system to differentiate between light requiring ghost image removal (through the quarter-wave plate) and light requiring image splitting (through the polarizing beam splitter), enabling both functions to coexist without interference.
2Object-affected harmful factors
If light is reflected back to the reflective liquid crystal device after passing through the projection lens, then the ghost image is formed, but preventing this requires complex optical configurations
Solution Approach 1:
The patent converts the harmful reflected light into a beneficial effect by using the quarter-wave plate to change its polarization state. The reflected light, which would normally cause ghost images, is transformed through the quarter-wave plate into light with a different polarization characteristic, causing it to be blocked by the polarizing beam splitter or redirected away from the liquid crystal device, thus eliminating the ghost image.
Solution Approach 2:
The patent changes the polarization parameter of the light using the quarter-wave plate. By altering the polarization state from linear to circular or elliptical, the system creates a parameter difference that allows the reflected light to be distinguished from the useful light and handled differently by subsequent optical elements, thereby preventing ghost image formation without requiring complex mechanical configurations.
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
This configuration effectively improves image quality by preventing ghost images, making it suitable for high-quality three-dimensional projections.
Implementation Method 1
a quarter-wave plate disposed between the reflective liquid crystal device and the imaging lens
Implementation Method 2
a means for correcting phase difference configured to correct a phase difference between a p-polarized light and an s-polarized light generated by the reflecting plane
Implementation Method 3
at least one reflective liquid crystal device configured to generate an image by modulating a polarization of the light emitted from the light source and reflecting the light
Implementation Method 4
an imaging lens configured to form a real image of the image generated by the reflective liquid crystal device
Implementation Method 5
a means for correcting phase difference configured to correct a phase difference between a p-polarized light and an s-polarized light generated by the reflecting plane
Data Source
AI summary
A projection display apparatus includes a light source configured to emit light, at least one reflective liquid crystal device configured to generate an image by modulating a polarization of the light emitted from the light source and reflecting the light, an imaging lens configured to form a real image of the image generated by the reflective liquid crystal device, a quarter-wave plate disposed between the reflective liquid crystal device and the imaging lens, an image splitter configured to include at least one reflecting plane and spatially split the real image into at least two split real images by reflecting the real image on the reflecting plane, at least two projection lenses configured to form the split real images again on a screen, and a phase difference corrector configured to correct a phase difference between a p-polarized light and an s-polarized light generated by the reflecting plane.