Laser Head Distance Control Using Resonant Period Measurement
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Solution Overview
Problem
Existing methods for distance control in laser processing using electrical oscillating circuits face a trade-off between measurement rate and resolution, where shortening the measurement interval for high dynamics results in reduced accuracy, especially for larger distances between the laser processing head and the workpiece.
Innovation Solution
Measuring the period of the oscillating circuit signal instead of counting signal edges, combined with frequency division and using a time-to-digital converter with a reference signal to enhance frequency resolution and accuracy, allows for precise distance determination even in short time intervals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the measurement interval is shortened to increase the measurement rate, then the measurement dynamics are improved, but the measurement resolution is reduced
Solution Approach 1:
The patent replaces the conventional edge-counting method with a period measurement method. Instead of counting signal edges within a fixed time window (which limits resolution when the window is short), the system measures the actual period of the oscillating circuit signal using a time-to-digital converter. This substitution of measurement methodology allows high-resolution distance measurement even with short measurement intervals, thereby increasing measurement rate without sacrificing resolution.
2Speed
If the measurement interval is shortened to achieve high dynamics, then the response speed is improved, but the frequency measurement accuracy is reduced
Solution Approach 1:
The patent substitutes the edge-counting approach with period measurement using a time-to-digital converter. By measuring the actual period duration rather than counting edges within a fixed interval, the system achieves high frequency measurement accuracy even with short measurement intervals. This enables fast response speed while maintaining the precision needed for accurate distance determination.
Solution Approach 2:
The patent changes the measurement parameter from edge count to period duration. By measuring the time duration of one complete oscillation period rather than counting multiple edges within a fixed interval, the system achieves both high measurement rate and high accuracy. The time-to-digital converter provides precise time measurement capability that maintains accuracy regardless of the measurement interval length.
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 high-accuracy distance measurement with high update rates and control dynamics for both short and large distances, improving the overall precision and reliability of distance control in laser processing.
Implementation Method 1
the capacitance between the nozzle tip and the workpiece is dependent on the distance, the frequency of the LC resonant circuit also changes as the distance between the nozzle tip and the workpiece changes as a result of the change in capacitance
Implementation Method 2
the capacitance is integrated into an electrical resonant circuit, in particular into an LC resonant circuit
Data Source
Figure 1~2
AI summary
The invention relates to a method for regulating a spacing during a laser machining process using an electric resonant circuit (17), the oscillation frequency of which depends on the spacing between a laser machining head (10) and a workpiece (14), and an adjusting device (23) for adjusting the spacing (d) between the laser machining head (10) and the workpiece (14). The aim of the invention is to allow a precise measurement of the spacing between the laser machining head (10) and the workpiece (14) with the precision and measurement rate required for the machining process. According to the invention, this is achieved in that the period duration of the resonant circuit signal is measured, and the spacing (d) between the laser machining head (10) and the workpiece (14) is ascertained on the basis of the measured period duration of the resonant circuit signal and fed to the adjusting device (23).