Linear Scale Thermal Expansion Compensation via Dual Encoder Reference
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Solution Overview
Problem
In bonding apparatuses, temperature-induced thermal expansion of linear scales leads to errors in movement precision, reducing the accuracy of electronic component mounting due to non-uniform expansion and varying thermal expansion amounts across different sites.
Innovation Solution
An apparatus with a movable body equipped with first and second detection units and a control unit that calculates a position compensation coefficient based on the ratio of graduations on a linear scale, allowing for precise movement correction by detecting graduation differences and adjusting movement amounts accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a linear scale is used to detect movement amount of the base, then movement detection is enabled, but thermal expansion of the linear scale causes errors in movement precision
Solution Approach 1:
The patent introduces a reference member with reference marks as an intermediary element. Instead of directly using the linear scale graduations for position detection, the system detects positions of reference marks on the reference member and uses these as a stable reference frame. This intermediary reference member is designed to have minimal thermal expansion or to expand uniformly, thereby mediating between the thermally expanding linear scale and the precision requirements of the bonding head positioning.
Solution Approach 2:
The patent changes the reference parameter from the linear scale graduations (which are subject to thermal expansion) to reference marks on a reference member (which have stable positional relationships). By changing what serves as the reference parameter for position detection, the system achieves temperature compensation without requiring active thermal control of the linear scale.
2Measurement precision
If the linear scale is used for position detection, then movement measurement is possible, but non-uniform thermal expansion reduces position detection precision
Solution Approach 1:
The reference member acts as a mediator that provides stable reference marks independent of the linear scale's thermal expansion characteristics. The reference marks are positioned on a structure that either expands uniformly or has negligible expansion, creating a stable reference frame that mediates between the unstable linear scale graduations and the precision requirements.
Solution Approach 2:
The system uses feedback by detecting the positions of reference marks and comparing them against expected positions. The control unit calculates actual positions based on detected reference mark positions and uses this feedback information to compensate for thermal expansion effects, continuously adjusting for temperature-induced changes.
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 solution improves movement precision by compensating for thermal expansion, ensuring accurate positioning of electronic components despite temperature changes, thereby enhancing the overall mounting precision.
Implementation Method 1
when the temperature of the bonding apparatus rises, the linear scale expands and an error occurs in the movement amount of the base that moves on the basis of graduations of the linear scale
Data Source
AI summary
The present invention is provided with: a base moving linearly relative to a substrate and having a first and second positions that are spaced apart from each other by a predetermined interval a in the movement direction; a linear scale where a plurality of graduations having a predetermined pitch are provided along the movement direction; encoder heads which respectively are disposed at the first and second positions of the base and detect first and second graduation numbers of the linear scale with respect to the first and second positions, wherein, as the base is moved along the linear scale, the first and second graduation numbers are detected in this order in the respective encoder heads, and the movement amount of the base is controlled on the basis of the ratio between the predetermined interval and the distance between the first graduation number and the second graduation number on the scale.