Surface-Structured Glass Marking Without Strength Loss
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Solution Overview
Problem
Laser structuring of glass surfaces for encoding, such as QR codes, introduces stresses and microcracks, reducing the strength of the glass and often requiring additional thermal or chemical treatments, which can lead to surface defects and increased risk of fracture.
Innovation Solution
A glass surface structuring method using pulsed laser ablation to create regions with higher roughness and a specific mechanical stress profile, where compressive stress transitions into tensile stress with increasing depth, maintaining adequate strength and readability of markings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If laser ablation is used to create surface structurings for encoding, then the readability of markings is improved, but the strength of the glass surface deteriorates due to introduced stresses and microcracks
Solution Approach 1:
The patent applies parameter changes by carefully controlling laser ablation parameters (pulse duration, energy density, scanning speed) to create surface structurings that achieve sufficient roughness for readable markings while limiting the depth and intensity of stress introduction. By optimizing these parameters, the process achieves the dual goal of marking readability and strength preservation.
Solution Approach 2:
The invention applies local quality by creating surface structurings only in specific regions where encoding is needed, rather than treating the entire glass surface. This localized approach ensures that markings are readable where required while leaving the majority of the glass surface intact and maintaining its original strength characteristics.
2Ease of manufacture
If laser ablation is used to create surface structurings, then markings can be made on glass surfaces, but additional thermal or chemical aftertreatment is required which increases process complexity and risk of surface defects
Solution Approach 1:
The patent extracts the unnecessary aftertreatment steps from the traditional laser marking process. By using optimized pulsed laser ablation parameters, the invention achieves complete marking creation in a single step without requiring subsequent thermal or chemical treatments, thereby simplifying the overall manufacturing process.
Solution Approach 2:
The laser ablation process performs multiple functions simultaneously: it creates the marking structure, controls surface roughness, and manages stress distribution within the glass. This self-service capability eliminates the need for separate aftertreatment processes that would otherwise be required to address potential defects or insufficient marking quality.
3Strength
If compressive stress is increased on the glass surface to improve strength, then fracture strength is enhanced, but the stress profile becomes more complex with transition to tensile stress at depth
Solution Approach 1:
The patent applies partial action by introducing compressive stress only to the necessary depth at the glass surface where it provides strengthening benefit. The laser ablation parameters are controlled so that compressive stress is concentrated near the surface while minimizing deeper penetration and stress complexity, achieving sufficient strength enhancement without excessive stress profile development.
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 method significantly enhances the fracture strength of glass elements in structured regions while maintaining the readability of markings, eliminating the need for subsequent annealing treatments and reducing the risk of surface defects.
Implementation Method 1
directing a pulsed laser beam onto the glass surface, the laser pulses of which remove glass from the glass surface by ablation
Implementation Method 2
the at least one structured region having a mechanical stress profile which can be measured by stress birefringence
Data Source
AI summary
A glass element includes a glass surface including a surface structuring with a structured region of the glass surface that, owing to glass removal, has a higher roughness than an adjoining unstructured region of the glass surface, the structured region having a mechanical stress profile which can be measured by stress birefringence. The structured region has a compressive stress on the glass surface that is higher in absolute terms than a stress in the adjoining unstructured region. At least one of the following is satisfied: the compressive stress becomes smaller in absolute terms with increasing depth and transitions into a tensile stress, a maximum tensile stress being smaller in absolute terms than the compressive stress on the glass surface; or the compressive stress has a value of less than 5 MPa in absolute terms on the glass surface and becomes smaller in absolute terms with increasing depth.