Lissajous Deflection Device Feedback Control
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Solution Overview
Problem
Existing Lissajous projection apparatuses face challenges in maintaining stable amplitude and phase over changing resonant frequencies due to external influences like temperature changes, requiring high damping which increases energy consumption and limits achievable optical deflection angles, making them unsuitable for high-resolution applications such as HDTV.
Innovation Solution
A deflection device with a high-quality factor (>3,000) and a feedback loop that regulates control frequencies based on measured phasing to keep oscillations within the resonant range, allowing for stable operation across a large temperature range with reduced energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high damping is used to maintain amplitude stability over changing resonant frequencies, then amplitude and phase stability are improved, but energy consumption increases and achievable optical deflection angles are limited
Solution Approach 1:
The patent implements a feedback loop that continuously monitors the resonant frequency of the deflection unit and dynamically adjusts the control frequency to track the resonant frequency. This active feedback mechanism replaces the need for high damping, maintaining amplitude stability without the energy penalty of heavy damping. The feedback system measures the actual resonant frequency and modifies the drive frequency in real-time to keep the system operating at resonance.
Solution Approach 2:
The patent transitions from a static, heavily damped system to a dynamic system where the control frequency actively adapts to changing resonant conditions. By making the control frequency variable and responsive to environmental changes, the system maintains stability without requiring high damping, thereby reducing energy consumption while preserving amplitude control.
2Stability of the object's composition
If high damping is used to maintain amplitude stability over changing resonant frequencies, then amplitude and phase stability are improved, but achievable optical deflection angles are limited
Solution Approach 1:
The feedback mechanism tracks the resonant frequency and adjusts the control frequency accordingly, allowing the system to operate at resonance with high Q-factor. This enables large optical deflection angles to be achieved while maintaining phase stability, as the system remains synchronized with its natural resonant frequency despite environmental variations.
Solution Approach 2:
The patent changes the operating parameters by using a high Q-factor resonant system with dynamically adjusted control frequency rather than a heavily damped system with fixed frequency. This parameter change allows the system to achieve both large deflection angles and phase stability by operating near resonance where the mechanical response is maximized.
3Device complexity
If constant control frequencies are used in Lissajous projection, then the projection process is simple, but amplitude and phase stability deteriorate when resonant frequency changes due to external influences
Solution Approach 1:
The patent introduces a feedback loop that monitors the resonant frequency and dynamically adjusts the control frequencies to track the resonant frequency. This feedback mechanism adds some complexity to the control system but dramatically improves amplitude and phase stability by ensuring the system always operates at or near resonance, overcoming the limitations of fixed frequency control.
Solution Approach 2:
The patent transitions from static control frequencies to dynamic control frequencies that adapt to changing resonant conditions. This dynamic approach allows the system to maintain stability despite environmental variations, with the control frequencies automatically adjusting to match the resonant frequency of the deflection unit.
4Stability of the object's composition
If a wide resonant curve with low quality factor is used to minimize amplitude change, then amplitude stability is improved, but energy consumption increases
Solution Approach 1:
The feedback loop continuously tracks the resonant frequency and adjusts the control frequency to maintain operation at resonance. This allows the system to use a high Q-factor (narrow resonant curve) efficiently, minimizing energy dissipation while maintaining amplitude stability through active frequency tracking rather than passive damping.
Solution Approach 2:
The patent changes the approach from using a wide resonant curve (low Q-factor) to using a narrow resonant curve (high Q-factor) with dynamic frequency adjustment. By making the control frequency variable and responsive to resonant frequency shifts, the system achieves amplitude stability with minimal energy loss, exploiting the high efficiency of high-Q resonant systems.
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
Enables high scanning and deflection frequencies with large optical deflection angles, maintaining amplitude and phase stability even with resonant frequency changes, suitable for high-resolution imaging while reducing energy consumption.
Implementation Method 1
mirrors are used which oscillate resonantly or almost resonantly in two axes and thus oscillate in a sinusoidal manner
Implementation Method 2
a feedback loop which regulates a first and/or second control frequency/frequencies of control signals in dependence on a measured phasing of oscillations of the deflection unit
Data Source
AI summary
The invention relates to a deflection device for a projection apparatus for projecting Lissajous figures onto an observation field which is made to deflect a light beam about at least one first and one second deflection axis for generating Lissajous figures having a deflection unit for producing oscillations about the deflection axes and having a control apparatus for producing control signals for the deflection unit having a first and second control frequency which substantially corresponds to the resonant frequencies of the deflection unit, wherein the deflection unit has a quality factor of >3,000 and the control apparatus includes a feedback loop which is configured to regulate the first and/or second control frequencies in dependence on a measured phasing of the oscillations of the deflection unit so that the maximum amplitude of the oscillations remains in the resonant range of the deflection unit. The invention further relates to a projection apparatus having such a deflection device as well as to a method for controlling a corresponding deflection device.