Laser Projection Device Resonant Scanning Distortion Correction
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Solution Overview
Problem
Existing laser projection devices face challenges in achieving a compact size while maintaining high-quality, distortion-free two-dimensional scanning due to issues with scanning speed uniformity and image distortion, particularly with sinusoidally driven mirrors that require complex optical systems and increased electrical loads.
Innovation Solution
A laser projection device employing a scanning device that performs deflection in one direction by resonant driving and another direction by non-resonant driving, with an incidence optical system providing convergent light in one direction and parallel light in the other, and a projection optical system comprising optical elements with varying powers to achieve constant-speed scanning and correct distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a sinusoidally driven mirror is used for deflection, then the scanning device can be simplified, but the scanning speed slows down at the periphery causing image quality deterioration
Solution Approach 1:
The patent changes the driving parameters of the mirror by introducing a resonance frequency component to the driving signal. This allows the mirror to operate at a resonant frequency that maintains constant scanning speed across the entire scanning range, eliminating the speed slowdown at periphery that occurs with simple sinusoidal driving.
Solution Approach 2:
The patent utilizes mechanical resonance by driving the mirror at its resonance frequency. This resonant driving enables the mirror to achieve larger deflection angles and maintain constant scanning speed without requiring complex multi-mirror systems, thus resolving the contradiction between device simplicity and scanning speed uniformity.
2Volume of moving object
If a galvanomirror or MEMS mirror is used, then the device can be compact, but distortion occurs on the two-dimensional image
Solution Approach 1:
The patent modifies the optical parameters by introducing a lens system with specific focal length and aperture characteristics. This optical system compensates for the distortion introduced by the resonant mirror deflection, enabling high-quality image projection while maintaining a compact device structure.
Solution Approach 2:
The patent introduces an intermediary optical system (lens and aperture stop) between the resonant mirror and the projection surface. This intermediary system acts as a mediator that corrects the distortion caused by the mirror's resonant deflection, allowing compact device design without sacrificing image quality.
3Productivity
If optical surfaces of different shapes are used for horizontal and vertical scanning, then both constant-speed scanning and distortion correction can be achieved, but the optical system becomes more complex
Solution Approach 1:
The patent employs a universal resonant mirror system that performs both horizontal and vertical scanning functions through a single mirror element. By using resonance driving, the same mirror structure achieves constant-speed scanning in both directions without requiring different shaped optical surfaces, thus reducing overall system complexity.
Solution Approach 2:
The patent changes the driving parameters and optical configuration to achieve constant-speed scanning in both horizontal and vertical directions using the same mirror system. By adjusting the resonance frequency and driving signal parameters, the system achieves multi-directional constant-speed scanning without requiring complex multi-surface optical systems.
4Device complexity
If convergent light is made incident on the MEMS mirror in both scanning directions, then the device structure can be simplified, but the projection optical system size becomes large and constant speed performance is difficult to achieve
Solution Approach 1:
The patent changes the optical parameter by introducing a lens system with specific focal length characteristics. This optical system allows parallel light to be incident on the resonant mirror while maintaining compact projection optical system size and achieving constant speed performance in both scanning directions.
Solution Approach 2:
The patent replaces the mechanical adjustment of mirror position with an optical solution using a lens system. Instead of mechanically adjusting the MEMS mirror to achieve proper light incidence, the patent uses a lens to transform the light path, achieving the same effect with a more compact and controllable optical system.
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 configuration enables a compact, high-quality, distortion-free two-dimensional scanning with improved brightness and reduced complexity, achieving a favorable balance between arcsine characteristics and distortion correction.
Implementation Method 1
a scanning device performing deflection in a first scanning direction by resonant driving
Implementation Method 2
performing deflection in a second scanning direction by non-resonant driving
Implementation Method 3
an incidence optical system having different optical powers in the first scanning direction and the second scanning direction and making light incident on the scanning device in a convergent state in the first scanning direction and in a substantially parallel light state in the second scanning direction
Implementation Method 4
a projection optical system having a negative optical power in the first scanning direction
Data Source
AI summary
A laser projection device includes: an incidence optical system condensing laser light, a scanning device deflect the laser light in a first scanning direction and a second scanning direction with a mirror, and a projection optical system guiding the deflected light to a surface to be scanned. The scanning device performs the deflection in the first scanning direction by resonant driving and performs the deflection in the second scanning direction by non-resonant driving. The incidence optical system has different optical powers in the first scanning direction and the second scanning direction, and makes light incident on the scanning device in a convergent state in the first scanning direction and in a substantially parallel light state in the second scanning direction. The projection optical system has a negative optical power in the first scanning direction.