Laser Crack Control for Cutting Transparent Workpieces
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Solution Overview
Problem
Current methods for cutting and separating glass substrates are inefficient, lacking in speed, cleanliness, cost-effectiveness, and reliability, particularly in the production of thin film transistors (TFT) and display materials for electronic devices.
Innovation Solution
A method involving the formation of a contour with defects in the glass substrate using a defect forming laser beam, followed by separation with an infrared laser beam that adjusts power and translation speed based on crack tip position and direction to induce consistent crack propagation, and temporarily halting irradiation during curved contour sections to manage heat accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional cutting methods are used to separate glass substrates, then the process is simple and equipment cost is low, but the cutting speed is slow, cleanliness is poor, and reliability is low
Solution Approach 1:
The patent replaces traditional mechanical cutting methods with a laser-based processing system. The laser beam induces cracks along the contour line by heating the glass substrate, eliminating the need for mechanical contact and significantly improving cutting speed and cleanliness while reducing tool wear and mechanical complexity.
Solution Approach 2:
The patent utilizes changes in optical parameters (laser wavelength, power, pulse duration) and thermal parameters (heating rate, temperature distribution) to control crack propagation. By adjusting these parameters, the system achieves precise control over the cutting process, enabling high-speed processing with clean edges and high reliability.
2Speed
If high power infrared laser beam is used to induce crack propagation, then cutting speed increases, but heat accumulation causes irregularities and reduces edge quality
Solution Approach 1:
The patent employs periodic or pulsed laser irradiation instead of continuous high-power irradiation. By delivering laser energy in controlled pulses, the system allows heat to dissipate between pulses, preventing excessive heat accumulation and irregular crack propagation while maintaining high crack propagation speed and edge quality.
Solution Approach 2:
The patent implements a feedback control system that monitors crack propagation in real-time and dynamically adjusts laser power and translation speed. This closed-loop control ensures that the laser parameters are optimized at each moment to maintain consistent crack propagation along the contour line, preventing heat accumulation and ensuring high edge quality.
3Reliability
If laser power and translation speed are kept constant, then the process is simple to control, but crack propagation becomes inconsistent especially along curved contours
Solution Approach 1:
The patent transitions from static (constant) laser parameters to dynamic (variable) parameters. The laser power and translation speed are continuously adjusted based on the contour geometry and real-time crack propagation status. This dynamic control ensures consistent crack propagation along both straight and curved contours, significantly improving reliability.
Solution Approach 2:
The patent uses real-time feedback from crack position detection to dynamically adjust laser power and translation speed. The control system receives information about crack propagation status and automatically modifies processing parameters to maintain optimal conditions, ensuring consistent results regardless of contour complexity.
4Productivity
If the laser beam continuously irradiates the workpiece during translation, then the process is continuous and efficient, but heat accumulates causing deviations from the contour line
Solution Approach 1:
The patent uses periodic irradiation with controlled pause intervals during translation. The laser beam is activated during critical phases of crack propagation and paused during curved contour sections where heat accumulation risk is high. This periodic action maintains processing efficiency while preventing contour deviations.
Solution Approach 2:
The patent implements feedback control that monitors crack propagation progress and contour position in real-time. Based on this feedback, the system dynamically determines when to continue or pause irradiation, ensuring that heat accumulation is prevented while maintaining continuous overall processing and high contour accuracy.
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 faster, cleaner, and more reliable separation of glass substrates with reduced irregularities, enhancing the strength and quality of the separated edges.
Implementation Method 1
directing an infrared laser beam output by an infrared beam source onto the transparent workpiece on or near the contour line to induce formation of a crack in the transparent workpiece
Implementation Method 2
translating the transparent workpiece and the infrared laser beam relative each other along or near the contour line to induce propagation of the crack along the contour
Data Source
AI summary
A method for processing a transparent workpiece includes forming a contour of defect in the transparent workpiece and separating the transparent workpiece along the contour using an infrared laser beam. During separation, the method also includes detecting a position and propagation direction of a crack tip relative to a reference location and propagation direction of an infrared beam spot, determining a detected distance and angular offset between the crack tip and the reference location of the infrared beam spot, comparing the detected distance to a preset distance, comparing the detected angular offset to a preset angular offset, and modifying at least one of a power of the infrared laser beam or a speed of relative translation between the infrared laser beam and the transparent workpiece in response to a difference between the detected distance and the preset distance and between the detected angular offset and the preset angular offset.