Capacitance Sensor Phase Detection for Laser Head Height Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing dynamic height adjusting systems for laser processing systems face limitations in reliability and process control due to signal interference, voltage fluctuations, and inability to continuously record measured capacitances during high-speed laser processing, especially when dealing with varying work piece shapes, materials, and thermal expansion.
Innovation Solution
A dynamic height adjusting system that uses a single frequency to monitor changes in phase, enabling accurate and continuous measurement of distance between the laser nozzle and the work piece, with adaptive control for various shapes, materials, and temperature corrections, utilizing a capacitance sensor and phase detection to maintain precise standoff height and accommodate non-flat work pieces and thermal variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex measured capacitance frequency distribution is used to determine thermal processing parameters, then measurement capability is provided, but signal determination delays and vulnerability to voltage fluctuations and interference occur
Solution Approach 1:
The patent extracts only the necessary measurement information by using a single frequency signal instead of analyzing the entire frequency distribution. This eliminates complex signal processing while retaining the essential capacitance measurement capability, thereby improving reliability without sacrificing measurement precision.
Solution Approach 2:
Instead of using multiple frequencies to achieve measurement (conventional approach), the patent inverts the approach by using a single frequency with phase modulation to extract capacitance information. This inversion simplifies the measurement system and reduces susceptibility to voltage fluctuations and interference.
2Productivity
If continuous recording of capacitances during laser pulses is required, then process control is improved, but signal interference and voltage fluctuation problems worsen
Solution Approach 1:
The patent implements continuous capacitance measurement throughout the laser processing cycle using a single frequency signal that can be continuously monitored. This maintains productivity by enabling real-time process control while the simplified single-frequency approach inherently reduces signal interference and voltage fluctuation issues.
Solution Approach 2:
The system continuously monitors phase changes in the single frequency signal and provides real-time feedback for height adjustment. This feedback mechanism enables continuous process control and productivity improvement while the robust single-frequency measurement resists signal interference and voltage fluctuations.
3Measurement precision
If multi-frequency capacitance analysis is used, then comprehensive measurement is achieved, but processing complexity and time increase
Solution Approach 1:
The patent extracts the essential measurement capability from complex multi-frequency analysis by using only a single frequency. This extraction maintains the core measurement function while eliminating unnecessary processing complexity, directly reducing device complexity without compromising measurement precision.
4Adaptability or versatility
If adaptive control for varying work piece conditions is implemented, then versatility is improved, but system complexity increases
Solution Approach 1:
The single frequency capacitance measurement system serves multiple functions: it measures height, detects work piece conditions, and provides feedback for adaptive control. This universal measurement approach improves versatility for handling various work piece conditions while maintaining relatively simple system architecture.
Solution Approach 2:
The system automatically adapts to varying work piece conditions through continuous phase monitoring and automatic height adjustment without requiring complex manual intervention or configuration. This self-service capability improves versatility while keeping the control system relatively simple.
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 system achieves enhanced process control and reliability by continuously monitoring phase changes, allowing for precise height adjustments and improved signal distribution, even during thermal expansion and variable work piece conditions, ensuring consistent performance across different materials and shapes.
Implementation Method 1
The capacitance sensor of the capacitive gauging system employs an oscillator. The frequency generated by the oscillator is a function of resistance, capacitance and/or inductance. As the distance between the tip of the laser head and the work piece changes, the capacitance changes, resulting in a change in the oscillator frequency.
Implementation Method 2
US 5 136 250 A discloses a process to determine the distance between a magnetic disc surface and a read/write head of a computer storage system based upon changes in the phase shift of an AC signal due to capacitive variations.
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The present invention relates to a dynamic height adjusting system and method that uses capacitance for a head assembly of a laser processing system throughout a process cycle. The proposed system and method involves use of a single frequency in which a change in phase is measured and processed to determine changes in height and distance between a work piece with an increased reliability, The system further enables operative computerized processor control and substantial improvements in process control signal and feedback distribution throughout an integrated system and optional remote interfaces.