MEMS Scanned Beam Projector Keystone Correction
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Solution Overview
Problem
Projectors face image distortion issues, such as keystone effect, when projecting at oblique angles or onto irregular surfaces, leading to reduced display resolution and image quality due to current correction methods like optical and digital keystone correction.
Innovation Solution
A microelectromechanical systems (MEMS) scanned beam projector system that detects and corrects image distortion by modulating the fast scan amplitude and interpolator active region as a function of vertical scan position, adjusting the MEMS vertical scan angle, and modifying the vertical ramp velocity profile to maintain image quality and resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If digital keystone correction is applied by prescaling the video image, then keystone distortion is corrected, but the number of individual pixels is reduced, thereby lowering display resolution and degrading projected image quality
Solution Approach 1:
The patent replaces digital image processing (software-based prescaling) with a mechanical/optical solution using a MEMS scanning platform. By dynamically adjusting the scanning angles and positions of the MEMS mirrors, the system corrects keystone distortion at the optical level rather than through digital resampling, thereby maintaining full pixel resolution while achieving distortion correction.
Solution Approach 2:
The patent changes the scanning parameters (angles and positions) of the MEMS platform dynamically based on detected distortion. By modifying the scan trajectory and timing, the system compensates for keystone effects without altering the pixel data, thus preserving display resolution while correcting image shape.
2Shape
If optical keystone correction is used to physically adjust the projector lens, then keystone distortion is corrected, but the projector must be positioned sufficiently far from the projection surface, limiting placement flexibility
Solution Approach 1:
The patent employs a dynamic MEMS scanning platform that can adjust its scanning parameters in real-time based on the detected distortion and projector position. This dynamic adjustment capability allows the system to correct keystone distortion at various distances from the projection surface, providing placement flexibility that static optical correction methods cannot achieve.
Solution Approach 2:
The system uses a feedback mechanism where a camera or sensor detects the actual projected image and distortion, then feeds this information back to adjust the MEMS scanning parameters. This closed-loop control enables the projector to automatically adapt to different positions and angles, maintaining image correction quality regardless of distance from the projection surface.
3Adaptability or versatility
If the projector is positioned at an oblique angle to the projection surface, then placement flexibility is improved, but keystone distortion and image quality degradation occur
Solution Approach 1:
The system uses real-time detection of the projected image shape and feeds this information back to adjust the MEMS scanning parameters. When the projector is positioned at an oblique angle causing keystone distortion, the feedback mechanism detects this distortion and automatically adjusts the scan trajectory to compensate, allowing flexible placement while maintaining proper image shape.
Solution Approach 2:
The dynamic MEMS scanning platform can adapt its scanning angles and positions in real-time to compensate for oblique projection angles. By dynamically adjusting the beam direction and scan pattern, the system maintains a rectangular image shape even when the projector is positioned at non-perpendicular angles to the projection surface.
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
Effectively corrects keystone distortion without reducing image resolution, ensuring a high-quality rectangular image projection even on non-planar surfaces by dynamically adjusting the MEMS scanning platform's operation based on real-time distortion detection.
Implementation Method 1
The output beam is incident on a scanning platform that includes a microelectromechanical (MEMS) based scanning platform. The output beam reflects off the scanning mirror to generate a controlled output beam that traverses a raster scan (or scan pattern) to create the displayed image on the projection surface.
Data Source
AI summary
Briefly, in accordance with one or more embodiments, a MEMS scanned beam projector includes a light source to emit a light beam, a scanning platform to redirect the light beam impinging on the platform, and a display controller to control the light source and the scanning platform to cause the scanning platform to scan the light beam in a vertical direction and a horizontal direction in a scan pattern to project an image onto a projection surface. The display controller is configured to correct for image distortion in the projected image by providing a compensated drive signal to the scanning platform to compensate for the image distortion.