Laser Projection Distortion Correction via Dynamic Mirror Synchronization
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Solution Overview
Problem
Conventional image projection systems using lasers suffer from keystone and pincushion optical distortions, where straight lines are bowed towards the center, and laser-generated light spots are distributed non-uniformly, leading to unequal pixel intensities along the horizontal axis due to the sinusoidal angular motion of the pivoting mirror.
Innovation Solution
A method and system that utilize a micro-mirror pivoting at non-uniform angular velocity about two axes, with a computerized representation of dense and sparse grids of spatial coordinates to synchronize mirror motion and laser operation, ensuring equal pixel intensities by varying the laser on-times and projecting pixels at uniformly distanced positions, thereby preventing image distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a micro-mirror pivots at non-uniform angular velocity about two axes to reflect laser beam over a 2D surface, then the projected image covers the entire surface area, but optical distortion occurs where straight lines are bowed towards the center point
Solution Approach 1:
The patent applies parameter changes by varying the laser modulation frequency dynamically during the mirror pivoting cycle. The laser is modulated at different frequencies corresponding to different angular positions of the mirror, allowing compensation for the non-uniform angular velocity and resulting optical distortions. This enables straight lines to be projected accurately despite the mirror's sinusoidal motion pattern.
2Productivity
If the laser beam is reflected by a pivoting mirror with sinusoidal angular motion, then the mirror can be synchronized with a high speed clock for modulation, but the light spots (pixels) are distributed non-uniformly rather than at equal intervals
Solution Approach 1:
The patent implements dynamics by making the laser modulation frequency variable rather than constant. The modulation frequency is dynamically adjusted based on the instantaneous angular position and velocity of the pivoting mirror. This dynamic adjustment ensures that pixels are projected at equal spatial intervals along the horizontal direction, compensating for the sinusoidal motion characteristics of the mirror while maintaining high projection speed.
3Ease of operation
If the laser operation is synchronized with mirror motion at constant frequency, then the system operation is simplified, but the intensities of pixels become unequal rather than equal across the image
Solution Approach 1:
The patent applies parameter changes by varying both the laser modulation frequency and the laser on-times dynamically. The modulation frequency is adjusted according to the mirror's angular position, and the laser on-times are varied to compensate for changes in pixel velocity across the projection surface. This ensures uniform pixel intensities across the entire image while maintaining synchronization with the mirror motion.
4Manufacturing precision
If the laser is modulated at varying time intervals to create pixels, then pixel distribution can be controlled, but the laser operation becomes more complex requiring different on-times for different pixels
Solution Approach 1:
The patent implements feedback by using the known sinusoidal motion characteristics of the pivoting mirror to determine the appropriate laser modulation parameters. The system calculates the required modulation frequency and on-times based on the mirror's angular position and velocity, creating a feedback loop that ensures accurate pixel placement. This approach manages complexity by using deterministic calculations based on the mirror's predictable motion pattern.
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 effectively prevents image distortion and ensures equal intensity of pixels across the projected image, maintaining image quality despite the non-uniform angular velocity of the micro-mirror, achieving a rectangular projection without keystone or pincushion distortions.
Implementation Method 1
a micro-mirror arranged for pivoting, at non-uniform angular velocity, about two axes, so as to reflect the coherent beam sequentially over the entirety of the 2D surface
Implementation Method 2
a laser which generates a coherent beam and is arranged to impinge upon a micro-mirror
Data Source
AI summary
A system for projecting 2D images, providing a computerized representation of a first, dense, grid of spatial 3D coordinates which respectively correspond to a set of time-points evenly distributed along a time-dimension with constant time-discretization; deriving a dense 2D representation of an image, whose coordinate pairs respectively correspond to said set of time-points; d. Defining a sparse 2D grid of second coordinate pairs, spaced such that distances between any two adjacent coordinate pairs along a row of said sparse 2D grid are constant; and finding, coordinate pairs closest to the second sparser grid to yield a third grid, and a laser controller to control the laser to project a digitally represented image, from said distance, timed to project pixels whose locations respectively correspond to the subset of uniformly distanced positions forming said third grid, thereby to prevent image distortion despite non-uniformity of micro-mirror's angular velocity.