Capacitance Electrode Pair for Lateral Workpiece Displacement Detection

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Solution Overview

Problem

Existing workpiece holding apparatuses cannot detect lateral displacement of a workpiece in the planar direction, relying on capacitance measurements that only assess the attraction state in the front-back direction, leading to insufficient detection of lateral displacement, which affects positional accuracy and manufacturing processes.

Innovation Solution

A workpiece holding apparatus equipped with a capacitance measuring device featuring an electrode pair at the peripheral edge of the workpiece, which measures capacitance changes to detect lateral displacement by comparing the measured values with a reference value using a comparator circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If capacitance measurement is used to detect workpiece holding state, then the attraction state in the front-back direction can be detected, but the lateral displacement in the planar direction cannot be detected

Engineering Contradiction:

Improvedetection capabilityVSAvoidlateral displacement information

Core Design Contradiction:

Measurement precisionVSLoss of information

Solution Approach 1:

The electrode structure is segmented into multiple electrode pairs arranged at different positions (peripheral edge and central portion) of the workpiece. Each electrode pair independently measures capacitance in the lateral direction, enabling detection of lateral displacement at different locations simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The detection capability is extended from the front-back direction (vertical dimension) to the lateral direction (horizontal dimension) by arranging electrode pairs laterally. This adds a new measurement dimension, enabling comprehensive detection of workpiece position in both vertical and horizontal directions.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Measurement precision

If a single capacitance measurement point is used, then the device structure remains simple, but the detection accuracy of lateral displacement is insufficient

Engineering Contradiction:

Improvelateral displacement detection accuracyVSAvoidelectrode configuration

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The detection system is divided into multiple electrode pairs positioned at different locations (peripheral edge and central portion). This segmentation enables multi-point lateral displacement detection, improving measurement accuracy while maintaining a relatively simple electrode configuration.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The electrode pairs serve dual functions: detecting both the holding state (front-back attraction) and lateral displacement (horizontal position). This multi-functionality improves detection accuracy without significantly increasing device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 easy and instantaneous detection of lateral displacement, enhancing the accuracy and reliability of workpiece positioning during manufacturing processes by using electrode pairs at the workpiece's edge to measure capacitance changes.

Implementation Method 1

a capacitance measuring device including an electrode pair formed of first and second electrodes and arranged at least at a part of a position corresponding to a peripheral edge portion of the workpiece, the capacitance measuring device measuring capacitance of the electrode pair

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS9689656B2Workpiece holder and method using same for detecting lateral displacement of workpiece

Publication Date: 2017.06.27 CREATIVE TECHNOLOGY CORP

AI summary

Provided are a workpiece holding apparatus capable of detecting lateral displacement of a workpiece (w) in a planar direction, and a method of detecting lateral displacement of a workpiece (w) with use of the workpiece holding apparatus. The workpiece holding apparatus, which is configured to hold the workpiece (w), with an adhesive pad (2) mounted on a support plate, includes: a capacitance measuring device (5) including an electrode pair formed of first and second electrodes (3a, 3b) and arranged at least at a part of a position corresponding to a peripheral edge portion of the workpiece (w), the capacitance measuring device (5) being configured to measure capacitance of the electrode pair; and a comparator circuit (6) configured to compare the measured capacitance with a predetermined reference value, to thereby detect lateral displacement of the workpiece (w) in a planar direction of the support plate (1). Further, the method of detecting lateral displacement of a workpiece (w) includes comparing the capacitance input to the comparator circuit (6) with a predetermined reference value, to thereby detect the lateral displacement of the workpiece (w).