MEMS Laser Scanner Dual-Frame Scanning for HD Resolution
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Solution Overview
Problem
MEMS laser scanning projectors face challenges in achieving high-definition image quality due to the mass of scanning mirrors, which limits their ability to operate at the high horizontal resonance frequencies required for HD resolutions, resulting in discontinuous images and manufacturing difficulties.
Innovation Solution
The use of a dual-frame scanning method with two modulated laser sources and a mirror mechanism comprising a fast horizontal scan mirror and a slow vertical scan mirror, where the lasers are aligned to cover a greater portion of the screen with a reduced horizontal scanning rate, allowing for a higher resolution image by alternating between two scan patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single laser source is used with conventional scanning, then the device structure is simpler, but the image resolution and quality are insufficient for HD requirements
Solution Approach 1:
The patent divides the scanning task into two separate scan patterns (first scan pattern and second scan pattern) that are alternately executed. This segmentation of the scanning process allows the system to achieve higher effective resolution by combining the coverage of both patterns, overcoming the limitation of single-pattern scanning while maintaining a relatively simple single-laser device structure.
Solution Approach 2:
The patent employs periodic alternation between two different scan patterns to achieve higher resolution. By repeatedly switching between the first scan pattern and the second scan pattern, the system accumulates coverage of more pixel locations over time, effectively doubling the resolution capability without requiring a more complex multi-laser system.
2Manufacturing precision
If the horizontal scanning rate is increased to achieve HD resolution, then the image quality improves, but the mirror mass limits the ability to operate at required frequencies
Solution Approach 1:
The patent dynamically alternates between two different scan patterns rather than attempting to continuously scan at extremely high speeds. This dynamic switching approach allows the mirror to operate at achievable speeds while still covering the necessary pixel locations through the combination of both patterns, effectively resolving the contradiction between scanning speed requirements and mirror mass limitations.
Solution Approach 2:
The patent introduces a temporal dimension to the scanning process by alternating between two spatial patterns. Instead of relying solely on increasing horizontal scanning speed in one dimension, the system uses pattern alternation over time to achieve higher effective resolution, thereby working around the physical speed limitations imposed by mirror mass.
3Ease of operation
If continuous vertical scanning is performed, then the scanning process is simpler to implement, but the scan lines are tilted and the image becomes discontinuous
Solution Approach 1:
The patent segments the scanning process into distinct first and second scan patterns, where each pattern is designed to scan specific portions of the image. By dividing the complete image into regions covered by different patterns and alternately executing them, the system achieves continuous and complete image coverage without the tilt and discontinuity problems of conventional continuous scanning.
4Stability of the object's composition
If diagonal scanning patterns are used to correct discontinuous images, then image continuity improves, but the mirror cannot move fast enough to generate required scan lines for HD resolution
Solution Approach 1:
The patent applies partial scanning action by having two different scan patterns each cover different portions of the complete image. Rather than requiring a single pattern to scan the entire image at extremely high speeds, each pattern scans a subset of lines, and their alternating execution combines to produce the complete HD-resolution image, thereby reducing the speed requirement for individual scan lines.
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 reduces the required horizontal resonance frequency by half, enabling the projection of higher resolution images with improved image quality and increased display resolution for a given scanning rate, while maintaining acceptable image coverage.
Implementation Method 1
directing the RGB laser beam to either a bi-axial mirror, or a set of two uni-axial mirrors working in tandem. The mirror or mirrors are controlled so as to move, or 'scan' the laser in a series of vertically spaced apart horizontal lines
Implementation Method 2
a first modulated laser source 101a and a second modulated laser source 101b... Each of the first modulated laser source 101a and the second modulated laser source 101b is comprised of three laser diodes
Data Source
Figure 1A~1D
Figure 2
Figure 3
AI summary
An electronic device includes a first laser source (101a) configured to project a first laser beam (107a), and a second laser source (101b) configured to project a second laser beam (107b) in alignment with the first laser beam in a first direction but at an angle with respect to the first laser beam in a second direction. A mirror apparatus (110) is positioned so as to reflect the first and second laser beams. Control circuitry (130) is configured to control the mirror apparatus to simultaneously reflect the first and second laser beams in a first scan pattern to form an first image, the first image formed from the first scan pattern having a number of scan lines greater than two times a horizontal resonance frequency at which the mirror apparatus oscillates divided by a desired frame rate of the first image.