Scanning Electron Microscope Table Positioning with Sliding Friction
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Solution Overview
Problem
Prior-art scanning electron microscopes experience decreased response characteristics and operational convenience due to backlash and torsional deformation in the motive force transmission system, particularly during startup or reversing of the x- and y-tables, leading to unstable and unsmooth table movements.
Innovation Solution
The scanning electron microscope incorporates sliding friction elements, such as x- and y-sliders, between the ball screws and cross roller guides to reduce backlash and instability, with these sliders being designed to minimize frictional force and deformation, allowing direct driving of ball screws by stepping motors inside the sample chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If ball screws and cross roller guides are used to move the x- and y-tables, then the tables can be easily moved due to small rolling friction, but the movements become slightly unsteady and unsmooth, causing unstable table movements
Solution Approach 1:
A slider is introduced as an intermediary component between the ball screw and the cross roller guide. The slider includes a sliding surface that contacts the cross roller guide, creating a sliding friction interface that stabilizes the table movement. This mediator transfers the driving force from the ball screw while providing friction-based stability through the sliding contact.
2Ease of operation
If cross roller guides are used to guide the x- and y-tables, then the tables can be moved with less friction, but backlash and torsional deformation occur in the motive force transmission system, decreasing response characteristics
Solution Approach 1:
The slider acts as an intermediary that connects the ball screw mechanism to the cross roller guide. By introducing this intermediate component with a sliding friction interface, the system maintains the ease of movement provided by rolling friction while adding stability through sliding friction, thereby improving response characteristics during startup and reversal.
3Force
If rolling friction elements are used to guide the tables, then the friction is reduced and movement is easier, but the table movements become unsteady particularly during startup or reversing
Solution Approach 1:
The slider introduces a sliding friction interface between the ball screw and cross roller guide system. This intermediary component provides just enough friction to stabilize table movements during startup and reversal, while maintaining overall ease of operation through the combined rolling and sliding friction mechanisms.
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 configuration improves the response characteristics and operability of the sample-moving stage by reducing backlash and instability, enabling stable and precise positioning even under high magnification.
Implementation Method 1
The scanning electron microscope incorporates sliding friction elements, such as x- and y-sliders, between the ball screws and cross roller guides to reduce backlash and instability
Data Source
AI summary
This invention stabilizes positioning and provides improved positioning accuracy in a scanning electron microscope provided with stage-driving means utilizing an effect of rolling friction.In this scanning electron microscope that includes a sample stage equipped with an x-table, a y-table, a z-table, a rotation table, and a tilting table, and moved by means of stepping motors each connected to a ball screw via a coupling, a sliding friction element is disposed at a position close to the ball screw, between the x-table and the y-table and between a tilting base and the x-table.