Dual-Valve Fluid Actuator Assembly for Fast, Precise Stage Positioning
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Solution Overview
Problem
There is a persistent challenge in reducing the cost of actuators used in exposure apparatuses while maintaining accurate positioning of masks and workpieces, such as in LCD flat panel displays and semiconductor wafers, as existing solutions often face limitations in velocity and accuracy due to back pressure issues in fluid actuator systems.
Innovation Solution
A stage assembly with a fluid actuator system that includes a piston housing, a piston separating two chambers, and a unique valve sub-assembly with different supply and exhaust orifice areas, allowing for controlled flow of working fluid to enhance positioning accuracy and speed, and a control system to manage these valves for precise movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fluid actuator system is used to position the stage, then the positioning accuracy can be improved, but the actuator velocity is limited due to back pressure issues
Solution Approach 1:
The patent applies parameter changes by making the exhaust orifice area larger than the supply orifice area. This asymmetric orifice configuration changes the flow parameters to reduce back pressure during exhaust, allowing faster actuator velocity while maintaining positioning accuracy through controlled supply flow.
Solution Approach 2:
The patent applies local quality by providing different orifice areas at different locations in the valve assembly - specifically, the exhaust orifice has a larger area than the supply orifice. This localized differentiation optimizes fluid flow characteristics for each function (supply vs. exhaust) to simultaneously achieve accuracy and speed.
2Speed
If the exhaust orifice area is increased to reduce back pressure, then the actuator velocity improves, but the valve complexity increases
Solution Approach 1:
The patent merges the supply and exhaust functions into a single valve assembly with differently sized orifices. This integration achieves the complex flow control requirements (different orifice areas for supply and exhaust) within one compact component, improving velocity without proportionally increasing overall valve complexity.
3Productivity
If different orifice areas are used for supply and exhaust valves, then the fluid flow control is optimized, but the manufacturing complexity increases
Solution Approach 1:
The patent combines multiple valve functions (supply and exhaust) into a single integrated valve assembly with differently sized orifices. This merging approach optimizes fluid flow control efficiency while actually reducing manufacturing complexity compared to using separate valves, as it eliminates the need for multiple separate components and their associated connections.
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 solution enables cost-effective and accurate positioning of workpieces by optimizing fluid flow through the valve sub-assembly, reducing back pressure, and allowing for faster actuator velocity and improved control resolution, thus addressing the cost and accuracy constraints of existing systems.
Implementation Method 1
The first supply valve has a first supply orifice having a first supply orifice area, and the first exhaust valve has a first exhaust orifice having a first exhaust orifice area. Moreover, the first supply orifice area is different from the first exhaust orifice area.
Implementation Method 2
a piston that is positioned within and moves relative to the piston chamber along a piston axis, the piston separating the piston chamber into a first chamber and a second chamber that are on opposite sides of the piston
Data Source
AI summary
A stage assembly (10) includes a stage (14), and a fluid actuator assembly (24) that moves the stage (14). The fluid actuator assembly (24) includes a piston housing (32) that defines a piston chamber (34); (ii) a piston (36) that separates the piston chamber (34) into a first chamber (34A) and a second chamber (34B); (iii) a supply valve (38C) that controls the flow of the working fluid (40) into the first chamber (34A); and (iv) an exhaust valve (38D) that controls the flow of the working fluid (40) out of the first chamber (34A). The supply valve (38C) has a supply orifice (250G) having a supply orifice area, and the exhaust valve (38D) has an exhaust orifice (352G) having an exhaust orifice area. Moreover, the supply orifice area is different from the exhaust orifice area. Further multiple valves of different sizes can be used in combination for the supply and exhaust for each chamber (34A), (34B).