Wrist Joint Nesting in SCARA Arm for Slot Valve Passage
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Solution Overview
Problem
The existing substrate transport systems face challenges in reducing the height of the wrist joint to enable passage through slot valve openings, leading to increased internal chamber volume and reduced throughput due to larger end effector pan offsets and swing diameters, which also increase costs.
Innovation Solution
The proposed solution involves reducing the height of the wrist joint by minimizing the amount of wrist pulley band/cable wrap, allowing at least part of the wrist joint to pass through the slot valve opening, thereby decreasing the internal volume of the transport chamber and enhancing end effector stiffness and throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the wrist joint height is reduced to enable passage through slot valve openings, then the end effector can pass through the slot valve opening, but the internal volume of the transport chamber increases and throughput decreases
Solution Approach 1:
The patent repositions the wrist joint from a location above the forearm to a location within the forearm, changing the spatial dimension of the wrist joint's position. This dimensional repositioning allows the wrist joint to pass through the slot valve opening while maintaining a compact overall structure that reduces chamber volume requirements.
Solution Approach 2:
The wrist joint is nested within the forearm structure, with the wrist joint pulley positioned inside the forearm rather than above it. This nesting arrangement compactly integrates the wrist joint into the existing forearm volume, reducing the overall height requirement without compromising functionality.
2Ease of operation
If the wrist joint height is reduced, then the slot valve opening can accommodate the wrist joint, but the end effector pan offset increases and reduces end effector stiffness
Solution Approach 1:
The patent changes the vertical positioning dimension of the wrist joint from above the forearm to within the forearm. This dimensional shift allows the end effector to maintain its structural integrity and stiffness while still accommodating passage through the slot valve opening by repositioning rather than extending components.
3Ease of operation
If the wrist joint height is reduced, then the slot valve opening can accommodate the wrist joint, but the swing diameter of the SCARA arm increases and reduces throughput
Solution Approach 1:
The wrist joint is nested within the forearm structure, compactly integrating it into the existing volume. This nesting reduces the overall swing diameter of the SCARA arm by eliminating the need for additional vertical space above the forearm, thereby improving throughput while maintaining passage capability.
4Ease of operation
If the transport chamber internal volume is increased to accommodate the wrist joint, then the wrist joint can pass through the slot valve opening, but the cost increases
Solution Approach 1:
The patent repositions the wrist joint to a lower vertical dimension within the forearm structure, allowing passage through the slot valve opening without requiring increased chamber volume. This dimensional repositioning maintains cost-effectiveness by avoiding larger chamber construction costs.
Solution Approach 2:
The wrist joint is nested within the existing forearm volume, utilizing already-available space rather than requiring additional chamber volume. This nesting approach avoids the increased manufacturing costs associated with larger transport chambers while still enabling passage through the slot valve opening.
Data Source
AI summary
A substrate processing apparatus including a frame, a SCARA arm mounted to the frame at a shoulder joint having two links with at least one end effector dependent therefrom, the links defining an upper arm and a forearm, each end effector pivotally joined to the forearm at a wrist to rotate about a wrist axis, and a drive section with at least one degree of freedom operably coupled to the arm to rotate the arm about a shoulder axis articulating extension and retraction, wherein the end effector is coupled to a wrist joint pulley so that extension and retraction effects rotation of the pulley and end effector as a unit about the wrist axis, and wherein a height of the end effector is within a stack height profile of the wrist joint so that a total stack height is sized to conform with and pass through a pass-through of a slot valve.