Light Beam Deflection Control for Uniform Circular Scanning
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Solution Overview
Problem
Conventional beam deflecting devices face challenges such as high mechanical inertia, irregular scanning speeds, and difficulty in achieving uniform pixel distribution due to resonant frequency differences, leading to issues like irregular edges in material cutting and inefficient image projection.
Innovation Solution
A control unit is used to control a projection device with two light beam deflection units, setting equal deflection frequencies to create a nearly circular path for the light spot on the target, allowing for efficient scanning of the imaging area with reduced external voltage requirements and precise control over light beam trajectory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional beam deflecting devices with movable mechanical elements are used, then the device can achieve two-dimensional deflection, but the mechanical inertia causes slow response to voltage changes
Solution Approach 1:
The patent replaces conventional mechanical beam deflecting devices with movable elements (galvanometer mirrors) with electro-optic deflectors that use the electro-optic effect in crystals. This substitution eliminates mechanical inertia and achieves inertia-free operation, dramatically improving response speed to voltage changes while removing complex mechanical structures.
Solution Approach 2:
The patent changes the operating parameters by applying high voltages (hundreds to thousands of volts) to electro-optic crystals to achieve the desired deflection. By utilizing the electro-optic effect parameter, the system achieves fast response without mechanical movement, resolving the contradiction between response speed and mechanical complexity.
2Length of moving object
If high voltages are applied to electro-optic deflectors to achieve desired deflection, then the deflection is sufficient, but the external voltage requirements increase
Solution Approach 1:
The patent employs resonant circuits to apply alternating voltages at the resonant frequency of the electro-optic crystal. This resonance amplification allows the system to achieve the required deflection with much smaller external voltages, as the resonant oscillation builds up the voltage internally, reducing the energy input requirement from external sources.
Solution Approach 2:
The patent utilizes the resonant frequency transition and phase relationships in the AC voltage application to the electro-optic crystal. By operating at resonance, the system transforms small external voltage inputs into large internal voltage oscillations, achieving the necessary deflection amplitude with minimal external energy input.
3Use of energy by stationary object
If resonant circuits are used to generate high voltages internally, then external voltage requirements are reduced, but the operation is restricted to a small frequency range
Solution Approach 1:
The patent dynamically adjusts the frequency of the AC voltage applied to the resonant circuit to match the resonant frequency of the electro-optic crystal. This dynamic frequency tuning allows the system to maintain resonant operation and achieve voltage amplification while adapting to the specific operational requirements, balancing the frequency range limitation with the benefit of reduced external voltage.
4Use of energy by stationary object
If the scanning speed varies due to sinusoidal voltage waveform, then resonant operation is achieved, but the impact points are irregularly spaced on the target
Solution Approach 1:
The patent incorporates feedback control mechanisms that monitor the position of impact points on the target and adjust the voltage waveform accordingly. This feedback allows the system to compensate for the sinusoidal speed variation, maintaining evenly spaced impact points while preserving the resonant operation and voltage amplification benefits.
Solution Approach 2:
The patent applies preliminary corrections to the voltage waveform to pre-compensate for the expected sinusoidal speed variation. By adjusting the voltage timing and amplitude in advance, the system ensures that impact points are evenly spaced on the target before the scanning variation occurs, maintaining manufacturing precision while utilizing resonant operation.
5Area of stationary object
If two deflectors with different resonant frequencies are combined, then two-dimensional deflection is achieved, but uniform pixel distribution becomes difficult
Solution Approach 1:
The patent carefully selects and balances the resonant frequencies of the two deflectors to create a symmetric scanning pattern that covers the entire imaging area uniformly. By adjusting the frequency ratio and amplitude of the two deflectors, the system achieves a Lissajous figure that provides uniform pixel distribution across the rectangular imaging area, resolving the asymmetry problem of non-uniform coverage.
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 enables efficient scanning of the entire imaging area with consistent pixel spacing, improving material processing accuracy and image projection quality by maintaining precision and speed while increasing the usable area and reducing external voltage demands.
Implementation Method 1
Electro-optic deflectors use crystals made of a material exhibiting an electro-optic effect. When a voltage gradient is applied to the crystal, a light beam propagating through the crystal is deflected.
Implementation Method 2
resonant circuits have been proposed to increase the voltage applied to the electro-optic crystal. Such resonantly enhanced electro-optic modulators may be operated with smaller external voltages because the high voltages required for the operation are internally generated.
Data Source
AI summary
A control unit (130) is provided for controlling a projection device (100) for directing a light beam (101) to a target (140). The projection device (100) comprises a light beam deflection unit (120) for two-dimensionally deflecting a light beam (101) in a first direction (x) with a first deflection frequency and in a second direction (y) with a second deflection frequency substantially equal to the first deflection frequency. The control unit (130) is configured to control the deflection unit (120) in such a way that a light spot (141) generated by the light beam (101) on the target (140) moves along a nearly circular path (144) changing its radius (R) over time.