Multi-mask alignment system for large shadow masks
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Solution Overview
Problem
The challenge in forming larger area shadow masks is maintaining accurate dimensional stability and preventing run-on errors in positioning openings across the dimensions of the shadow mask, which becomes increasingly difficult as mask sizes grow.
Innovation Solution
A multi-shadow mask alignment system comprising a carrier with apertures, combination frames and shadow masks, an alignment system, and a control system with digital cameras and programmed controllers to precisely align and adjust the positions of multiple smaller shadow masks in X, Y, and θ directions to form a larger effective shadow mask.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If larger area shadow masks are formed, then the coverage area increases, but the dimensional stability and positioning accuracy deteriorate
Solution Approach 1:
The patent divides a large shadow mask into multiple smaller sub-masks, each with its own frame and alignment features. These sub-masks are positioned on a carrier and independently aligned using the alignment system, allowing each to maintain dimensional stability while collectively covering a larger area.
Solution Approach 2:
The patent introduces alignment features and an alignment system as intermediaries between the sub-masks and the carrier. These alignment features enable precise positioning and dimensional stability of each sub-mask relative to the carrier and to each other, resolving the dimensional stability issue in large-area masks.
2Area of stationary object
If larger area shadow masks are formed, then the coverage area increases, but the positioning accuracy of openings deteriorates
Solution Approach 1:
By segmenting the large mask into smaller sub-masks, each sub-mask can be manufactured with high positioning accuracy. The alignment system then ensures that these accurately positioned sub-masks maintain their relative positioning when assembled on the carrier.
Solution Approach 2:
The patent replaces mechanical positioning methods with an optical alignment system that uses alignment features and digital imaging to achieve precise positioning. This substitution enables higher measurement and positioning accuracy across the large area.
3Manufacturing precision
If smaller shadow masks are used to construct larger area, then the dimensional stability improves, but the system complexity increases
Solution Approach 1:
The alignment system is designed as a universal platform that can handle multiple sub-masks with different patterns and sizes. The same alignment features and alignment mechanism are used for all sub-masks, reducing the need for multiple specialized systems and managing complexity.
Solution Approach 2:
The patent uses digital imaging to create copies of alignment feature positions, allowing the control system to calculate and adjust positions based on captured images. This copying approach simplifies the alignment process by replacing complex mechanical measurements with optical copying and computational positioning.
Data Source
AI summary
In a multi-mask alignment system and method, a carrier frame is provided having a number of apertures therethrough. A number of shadow mask-frame combinations are also provided. Each shadow mask-frame combination includes a first set of alignment features and each shadow mask-frame combination is positioned on a first side of the carrier with the frame supporting the shadow mask in alignment with one of the apertures. A single alignment stage is provided and a control system including a programmed controller is also provided. Under the control of the controller, the single alignment stage translates to each shadow mask-frame combination, one-at-a time, and adjusts the position of the shadow mask-frame combination based on positions of the first set of alignment features determined by the controller.