Scanned Beam Display Parallelogram Distortion Correction
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Solution Overview
Problem
Compact scanned beam displays face challenges in achieving ideal raster scanning due to inertia, leading to image resolution issues and parallelogram distortion, where the slow-scan axis drive signal couples with the fast-scan axis movement, causing a square image to appear slanted.
Innovation Solution
A scanning platform with non-orthogonal torsion arms and a modified gimbal configuration that corrects parallelogram distortion by orienting the first and second axes at a specific angle, allowing for hardware-based correction without requiring complex processing or software algorithms, using a single drive signal to pivot the scanning mirror about both axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a sinusoidal scan function is used to drive the scanning platform, then the scanning platform can move more efficiently and produce images in compact systems, but image resolution problems and parallelogram distortion occur
Solution Approach 1:
The patent changes the geometric parameters of the scanning platform by introducing non-orthogonal torsion arms at a specific angle (e.g., 45 degrees) relative to the scanning axes. This physical parameter modification compensates for the distortion introduced by sinusoidal scanning, allowing the system to maintain both scanning efficiency and image resolution accuracy without requiring complex software correction algorithms.
2Device complexity
If the scanning platform uses standard orthogonal torsion arms, then the structure is simple, but parallelogram distortion occurs where the slow-scan axis drive signal couples with the fast-scan axis movement
Solution Approach 1:
The patent introduces asymmetry in the scanning platform structure by configuring the torsion arms at non-orthogonal angles (e.g., 45 degrees) relative to the scanning axes rather than using standard orthogonal arrangements. This asymmetric configuration creates a geometric relationship that compensates for the coupling between slow-scan and fast-scan axis signals, eliminating parallelogram distortion while maintaining relatively simple hardware implementation.
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 solution effectively corrects parallelogram distortion, ensuring a near-perfectly projected image by adjusting the angle of the static magnetic field and torsion arms, allowing for efficient image scanning and improved image quality in compact projection systems.
Implementation Method 1
A scanning platform is provided that pivots a scanning mirror about a first axis and a second axis in response to a drive signal having first and second axis drive signals, respectively. The scanning platform includes a static magnetic field that is responsive to the first and second axis drive signals.
Implementation Method 2
A scanning platform with non-orthogonal torsion arms and a modified gimbal configuration that corrects parallelogram distortion by orienting the first and second axes at a specific angle
Data Source
AI summary
A scanning assembly (400) for use in a scanning display includes a reflective scanning surface, such as a scanning mirror (412). The reflected scanning surface can be mounted on a scan plate (409). The scanning assembly (400) is configured to pivot about a first axis (403) and a second axis (404) to form an image. To correct parallelogram distortion, the first axis (403) and second axis (404) are non-orthogonal relative to each other. Torsion arms (407,408) facilitating rotation of the scanning mirror (412) along one axis (403) can be oriented non-orthogonally relative to other torsion arms (413,414) by an amount sufficient to correct parallelogram distortion.