Projection Apparatus Keystone Correction via Image Compression
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Solution Overview
Problem
Conventional projection apparatuses with small volumes face keystone distortion issues when projecting images, leading to decreased image quality, and existing calibration methods are costly and complex.
Innovation Solution
A projection apparatus comprising an image panel, a projection lens, and a control unit that tilts the optical axis, where a first portion of the displaying area shows a compressed frame and a second portion shows a black border, with the compressed ratio relative to the tilt angle, maintaining image quality while reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the optical axis is tilted with respect to the screen normal, then the projection apparatus can be positioned more flexibly, but keystone distortion occurs and image quality decreases
Solution Approach 1:
The control unit pre-processes the image data by compressing the frame in the vertical direction according to the tilt angle before transmission to the image panel. This preliminary compression counteracts the keystone distortion that will occur during projection, allowing the optical axis to be tilted while maintaining image quality.
Solution Approach 2:
The system changes the parameter of frame compression ratio based on the tilt angle of the optical axis. By dynamically adjusting the compression parameter according to the actual tilt angle, the system compensates for keystone distortion and maintains image quality across different positioning scenarios.
2Manufacturing precision
If optical keystone calibration is used to correct the distortion, then image quality is improved, but the cost of the projection apparatus increases
Solution Approach 1:
The patent replaces the mechanical/optical keystone calibration system with an electronic image processing system. Instead of using additional optical elements or mechanical adjustment mechanisms, the control unit electronically compresses the image frame according to the tilt angle, achieving the same correction effect at lower cost.
3Manufacturing precision
If conventional electronic keystone calibration is used to correct the distortion, then image quality is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts only the essential function needed for keystone correction - vertical frame compression based on tilt angle - from the complex conventional electronic keystone calibration system. By implementing only this specific function, the system achieves image quality improvement while significantly reducing device complexity.
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 approach achieves good image quality through a simple method, reducing the overall cost of the projection apparatus by correcting keystone distortion without the need for expensive optical calibration.
Implementation Method 1
The projection lens is disposed on a transmission path of the image beam and has an optical axis. The projection lens is configured to project the image beam to form an image.
Data Source
AI summary
A projection apparatus including an image panel, a projection lens, and a control unit is provided. The image panel is configured to provide an image beam and has a displaying area. The projection lens is configured to project the image beam to form an image. When the optical axis of the projection lens is tilted with respect to a normal of the image, the control unit commands a first portion of the displaying area to show a compressed frame corresponding to the image and commands a second portion of the displaying area to show a black border. A projection method is also provided.