Laser PWM Correction for Uniform Engraving After Long Pauses
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Solution Overview
Problem
Existing laser processing devices face deviations between actual and target power due to non-ideal laser source characteristics, leading to suboptimal engraving quality, especially at the start of the process and during long pauses, and require extensive testing to compensate for these errors.
Innovation Solution
A method for defining a laser control signal that includes a correction process to adjust the PWM signal based on pause duration and pulse duration, determining a correction value to optimize the signal, ensuring high engraving quality across various frequency and duty cycle ranges, and reducing the need for initial heating and high power settings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If constant pulse lengthening (increased duty cycle) is used to compensate for laser power deviations, then engraving quality improves in certain frequency/duty cycle ranges, but errors are amplified in other ranges and the solution is limited to specific operating conditions
Solution Approach 1:
The patent implements dynamic correction by continuously monitoring actual laser power and adjusting the duty cycle in real-time based on measured deviations. Unlike static compensation methods that use fixed duty cycle increases, this system adaptively modifies pulse parameters throughout the machining process to maintain consistent power delivery across varying operating conditions.
Solution Approach 2:
The system changes multiple PWM parameters (duty cycle, pulse width, frequency) based on measured power deviations and pause durations. By dynamically adjusting these parameters rather than relying on a single fixed correction, the system achieves consistent engraving quality across a wide range of operating conditions without amplifying errors in any specific range.
2Manufacturing precision
If extensive testing with various settings is performed to compensate for laser errors, then sufficient engraving quality can be achieved, but the process time and complexity increase significantly
Solution Approach 1:
The patent employs closed-loop feedback by continuously measuring actual laser power during operation and using this information to dynamically adjust PWM parameters. This real-time feedback eliminates the need for extensive pre-processing testing, as the system self-corrects power deviations automatically during the machining process itself.
Solution Approach 2:
The system performs self-correction by automatically detecting power deviations and adjusting its own control parameters without requiring external intervention or extensive manual testing. The laser processing system serves itself by monitoring and compensating for its own non-ideal characteristics in real-time.
3Manufacturing precision
If high power settings are used to ensure adequate engraving quality, then engraving quality improves, but afterglow increases and sensitive materials are adversely affected
Solution Approach 1:
The system dynamically adjusts pulse duration and duty cycle based on actual power measurements and pause durations, allowing it to achieve consistent engraving quality at lower average power levels. By optimizing the timing and intensity of individual pulses rather than maintaining continuously high power, the system reduces afterglow while maintaining quality.
4Manufacturing precision
If the laser source is heated before machining to improve quality at the start of the process, then initial engraving quality improves, but the overall process time increases
Solution Approach 1:
The system performs preliminary characterization of the laser source's pause duration effects before production machining, storing this information for use during actual processing. This pre-characterization allows the system to immediately apply appropriate corrections at the start of machining without requiring heating time, as the correction parameters are determined in advance through automated testing.
Data Source
AI summary
The present disclosure relates to a laser plotter, a galvo marking laser and a method for defining a laser control signal for a laser source for various types of laser machines, for cutting, engraving, marking and/or lettering of a workpiece, in which at least one laser source is used in a housing of the laser machine type for processing a workpiece. A PWM signal for controlling the laser source is generated by a control unit. The workpiece is deposited on a processing table and the processing of the workpiece carried out line by line, whereby a separate PWM signal for driving the laser source is generated for each line. At a defined edge, a correction process is carried out to generate a modified PWM signal, wherein the correction process determines the preceding pause duration and the pulse duration, from which a correction value and a correction factor, respectively, are determined.