Scanning Projection Apparatus Resonant Mirror Modulation
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Solution Overview
Problem
Conventional laser projection systems face challenges in achieving high-frequency modulation for gray scale representation due to mechanical stability issues and high operational power requirements, particularly in micromechanically manufactured scanning projectors, which limit the miniaturization and cost-effectiveness of the deflection unit.
Innovation Solution
A projection apparatus that modulates the intensity of the radiation beam by changing its intensity within a specific time interval while scanning a pixel, using a binarily modulated laser with adjustable impulse duration and duty cycle, allowing for continuous or multi-step brightness adaptation, and combining this with amplitude modulation to achieve high-frequency modulation without constant scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If resonant scan is used for high-frequency modulation, then gray scale representation is improved, but mechanical stability deteriorates due to high deflection frequencies inducing dynamic deformation of the mirror plate
Solution Approach 1:
The patent applies periodic pulsed action by modulating the laser beam in synchronized pulses during the resonant scan cycle. The laser is activated only during specific time windows when the scanning point is positioned at the correct location, rather than continuous operation. This periodic activation achieves high-frequency gray scale representation while allowing the mirror plate to return to its stable rest position between pulses, reducing cumulative dynamic deformation and maintaining mechanical stability.
2Productivity
If resonant vertical row deflection is used, then image projection is achieved, but horizontal column frequency must be very high which induces dynamic deformation of the mirror plate
Solution Approach 1:
The patent implements periodic action by activating the laser beam only during specific time intervals when the scanning point passes through the correct position during resonant scan. This pulsed operation eliminates the need for continuous high-frequency horizontal deflection, significantly reducing dynamic deformation stress on the mirror plate while maintaining effective image projection capability.
3Stability of the object's composition
If quasi-static vertical row deflection is used, then mechanical stability is maintained, but very high operating powers are necessary which prevent miniaturization
Solution Approach 1:
The patent employs periodic pulsed operation where the laser beam is activated only during specific time windows synchronized with the resonant scan cycle. This allows the system to use lower average operating power compared to continuous quasi-static operation, enabling miniaturization of the deflection unit and control system while maintaining mechanical stability through the natural resonance of the mirror plate.
4Manufacturing precision
If linear scan with high line frequency is used, then column representation is improved, but the ratio of line frequency to column frequency limits the number of resolvable lines
Solution Approach 1:
The patent utilizes mechanical vibration by operating the deflection mirrors at their resonant frequencies. This resonance-based approach naturally provides the required high line frequencies for fine column representation without requiring complex frequency ratio control. The resonant oscillation of the mirror plate inherently generates the sinusoidal deflection patterns needed, simplifying the control system while achieving high manufacturing precision for column representation.
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 enables efficient and cost-effective gray scale representation with high modulation frequency, reducing the need for constant laser power and minimizing mechanical stress, thus improving the resolution and energy efficiency of the projection system.
Implementation Method 1
the achieving of low eigenfrequencies or resonance frequencies poses a fundamental problem, since the mechanical stability of the system decreases with the eigenfrequency. If the vertical deflection is to be excited in resonance or resonantly
Implementation Method 2
modulating an intensity of the radiation beam such that the intensity of the radiation beam changes from a first value to a second value within a time interval during which a scan point to which the radiation beam is directed sweeps a pixel of the image field
Data Source
AI summary
A projection apparatus for scanningly projecting an image onto an image field by means of a radiation beam includes a modulator for modulating an intensity of the radiation beam such that the intensity of the radiation beam changes in a time interval during which a scan point to which the radiation beam is directed sweeps a pixel of the image field.