Shadow Mask Tensioning via Thermal Expansion
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Solution Overview
Problem
Existing methods for tensioning shadow masks in physical vapor deposition processes are difficult to control for uniformity, leading to non-uniform tension and deformations, especially in designs with tight tolerances, and are prone to mechanical failures and high costs.
Innovation Solution
A method involving a tensioning frame that expands uniformly due to elevated temperature, applying tension to the shadow mask between rigidly clamped frame halves, followed by a mounting frame to maintain uniform tension without mechanical actuators, using materials with high strength, thermal conductivity, and coefficient of thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If clamp bars are used to tension the shadow mask, then the mask can be held in place, but non-uniform tension is introduced leading to deformations
Solution Approach 1:
The patent replaces the mechanical clamp bar system with a thermal expansion system. The shadow mask is clamped between two plates, and heating causes the plates to expand uniformly, applying even tension across the entire mask perimeter without the localized stress concentrations caused by clamp bars. This eliminates deformations and maintains alignment precision.
Solution Approach 2:
The patent changes the physical state of the tensioning system by using temperature as a control parameter. By heating the tensioning plates, their dimensional parameters change (expand), which in turn applies uniform tension to the shadow mask. This continuous adjustable parameter allows for precise control of mask tension without mechanical adjustments.
2Force
If pneumatic, hydraulic, or mechanical actuators are used to apply forces to clamp bars, then tension can be applied to the mask, but the control becomes difficult and the system becomes complex
Solution Approach 1:
The patent eliminates complex mechanical actuators (pneumatic, hydraulic, or mechanical) by using thermal expansion of solid plates. The tensioning force is generated passively through controlled heating, removing the need for active actuators and their associated control systems. This dramatically simplifies the device while maintaining the ability to apply and control tension.
Solution Approach 2:
The tensioning plates perform the dual function of both clamping the mask and generating the tensioning force through their own thermal expansion. The system is self-regulating in that the amount of expansion (and thus tension) is directly proportional to the temperature increase, providing automatic control without external actuators.
3Force
If clamp bars are used to tension the shadow mask, then the mask can be held, but the portion in direct contact cannot stretch introducing non-uniformities
Solution Approach 1:
The patent replaces the localized contact of clamp bars with distributed contact across the entire mask perimeter. The heated plates expand uniformly in all directions, applying tension evenly along the whole edge of the shadow mask. This eliminates the non-uniformities caused by discrete clamp bar contact points and ensures reliable, consistent tension across the entire mask.
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 method achieves extremely uniform tension in shadow masks with simple, low-cost, and reliable equipment, reducing maintenance and calibration needs, and ensuring consistent performance.
Implementation Method 1
elevating the temperature of the tensioning frame, causing the tensioning frame to expand and place the shadow mask in tension
Data Source
AI summary
A method for tensioning a shadow mask includes positioning a first side of a shadow mask into contact with the lower half of a tensioning frame, positioning an upper half of the tensioning frame into contact with a second side of the shadow mask, and clamping the upper half of the tensioning frame to the lower half of the tensioning frame to form a tensioning frame, and rigidly clamping the shadow mask between the two tensioning frame halves. The method also includes elevating the temperature of the tensioning frame to tension the shadow mask.