Gantry Positioning Device Flexible Frame Rotation
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Solution Overview
Problem
Existing gantry-type positioning devices are complex and costly to produce due to the need for high-quality materials and precise machining, and they do not allow for rotation about a third direction perpendicular to the plane, which is necessary for precise positioning in semiconductor fabrication.
Innovation Solution
A gantry-type positioning device with a flexible frame design that allows for rotation about a third direction perpendicular to the plane, using only one high-quality guide beam for precise machining, while the other beams can be made from less expensive materials like aluminum, and incorporating flexure joints and air bearings for precise movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a movable frame with flexure joints is used to enable rotation about the third direction, then positioning capability in three degrees of freedom is improved, but device complexity and manufacturing cost increase due to requiring very high-quality materials and precisely machined guide surfaces for lateral air bearings
Solution Approach 1:
The patent extracts the guidance function from the complex movable frame structure and relocates it to the stationary base. The base provides guide surfaces that directly guide the movable element, eliminating the need for complex flexure joints and lateral air bearing guide surfaces on the frame itself. This reduces frame complexity while maintaining the ability to position in three degrees of freedom.
Solution Approach 2:
Instead of having the movable frame provide guidance surfaces for the movable element (as in prior art), the patent inverts the arrangement by providing guide surfaces on the stationary base that guide the movable element directly. This reverses which component bears the guidance function, simplifying the movable frame structure.
2Manufacturing precision
If very high-quality materials and precisely machined guide surfaces are used for lateral air bearings on the frame, then positioning precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent extracts the precision guidance function from the expensive movable frame structure and places it on the stationary base. The base, being stationary and easier to machine with high precision, carries the guide surfaces for lateral air bearings. This allows achieving high positioning precision without the need to machine expensive movable frame components with such precision.
Solution Approach 2:
The patent replaces expensive, difficult-to-manufacture high-quality frame materials with cheaper, more easily manufactured materials for the frame. The precision requirements are transferred to the base, which can use standard machining practices, while the frame can use more economical materials like aluminum alloys.
3Ease of manufacture
If a rigid frame is used, then manufacturing simplicity is improved, but positioning capability is limited as the movable element cannot be rotated about the third direction
Solution Approach 1:
The patent replaces the mechanical flexure joint system with a virtual guidance mechanism. Instead of using physical flexure joints to enable rotation, the system uses guide surfaces on the base combined with air bearings to enable the movable element to rotate about the third direction while maintaining positioning capability. This substitution achieves rotation capability without complex mechanical joints.
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
Enables highly precise positioning in three degrees of freedom within a plane while reducing production costs and material usage, allowing for lighter and more dynamic positioning with minimal torque generation and friction.
Implementation Method 1
The frame and the movable element are guided by means of air bearings on a base of the positioning device
Implementation Method 2
the movable element being guided in addition by lateral air bearings along the two transverse beams of the frame
Data Source
AI summary
A gantry-type positioning device includes a planar base parallel to first and second directions. Two first linear axes are arranged in the first direction, each having a first linear drive. A frame held by the first linear axes is movable in the first direction, and comprises two transverse and two longitudinal beams. The transverse beams carry second linear axes with second linear drives parallel to the second direction, so that a movable element arranged between the transverse beams is movably held by the second linear actuators. The frame is flexibly constructed such that the movable element is rotatable about a third direction which is perpendicular to the first and second directions. With respect to the third direction, the movable element is guidable by a guide surface of only one of the transverse beams serving as a guide beam for the movable element.