Projection Apparatus with Non-Telecentric Illumination for Distortion Control
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Solution Overview
Problem
Rear projection display products suffer from image distortion due to varying incident angles of image beams, leading to poor image quality, exacerbated by offsets between the optical axis and imaging device.
Innovation Solution
A projection apparatus with a non-telecentric illumination system, featuring a light valve with distinct pixel regions and an optical actuation element that adjusts the transmission path lengths of sub-image beams to minimize refraction differences, ensuring closer incident angles and reduced distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a transparent plate is used to change the transmission direction of the image beam to achieve higher resolution, then the image resolution is improved, but image distortion occurs due to varying incident angles of off-axis beams
Solution Approach 1:
The illumination system is designed with different illumination paths for different regions of the light valve. Chief beams (from the optical axis) and off-axis beams (from adjacent regions) are provided with different illumination conditions, specifically different incident angles, to compensate for the refraction differences caused by the transparent plate. This local differentiation of illumination quality resolves the distortion issue while maintaining the resolution enhancement benefit.
2Ease of operation
If the optical axis of the lens is offset from the imaging device to accommodate the projection structure, then the projection layout is simplified, but the distortion phenomenon becomes more severe
Solution Approach 1:
The illumination system pre-compensates for the distortion that will be caused by the offset between the optical axis and imaging device. By adjusting the incident angles of the illumination beams before they reach the light valve and transparent plate, the system counteracts the expected refraction-induced distortion, thereby maintaining image quality despite the necessary offset for practical projection layout.
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 achieves improved image quality by minimizing refraction-induced distortions, allowing for better alignment and overlap of image frames, thereby enhancing resolution and reducing distortion to less than 3% pixel displacement.
Implementation Method 1
The light valve includes an image display surface, and is configured to convert the illumination beam into an image beam
Implementation Method 2
when the transparent plate is deflected to the angle, the deflected image beam is projected to another predetermined position on the screen through the lens
Implementation Method 3
JP 2006 023574 A describes a reflection prism mounted on an optical box
Implementation Method 4
The projection lens is configured to receive the image beam coming from the optical actuation element, and projects the image beam on a display medium to form an image frame
Data Source
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AI summary
A projection apparatus including an illumination system, a light valve, an optical actuation element and a projection lens is provided. The illumination system provides an illumination beam. An image display surface of the light valve includes a first region and a second region. First pixels of the first region convert the illumination beam into first sub-image beams. Second pixels of the second region convert the illumination beam into second sub-image beams. A transmission path of one of the first sub-image beams in the optical actuation element is a first transmission path. A transmission path of one of the second sub-image beams in the optical actuation element is a second transmission path. A length of the first transmission path is smaller than a length of the second transmission path. In this way, the projection apparatus has good image quality.