Optical Tool Position Sensing for Chuck Table Home Alignment

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional methods for determining the home position of grinding stones or cutting blades in grinding and dicing apparatuses require skilled operators and are prone to inaccuracies due to relative shifts between detecting units and chuck tables, or tool wear and damage.

Innovation Solution

A measuring apparatus using a broadband light source, mirror, chromatic aberration condensing lens, and position detecting unit to accurately determine the positional relation between the chuck table and processing tools by analyzing the intensity of reflected light across different wavelengths, allowing for precise detection of the home position without operator expertise.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional contact method is used to determine home position by bringing grinding stone into contact with chuck table, then home position can be determined, but the process becomes tedious and time-consuming requiring skilled operators

Engineering Contradiction:

Improvehome position determination accuracyVSAvoidorigin determining process time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical contact method with an optical measurement system. A light source emits light toward the processing tool, and a light receiving element detects the reflected or blocked light to determine the home position automatically, eliminating the need for manual mechanical contact and skilled operator intervention.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system enables automatic home position determination through self-service mechanism. The processing tool itself interacts with the optical field (blocking or reflecting light), and the control unit automatically processes the signal to determine home position without requiring operator skill or manual intervention.

Inventive Principle:

Principle #25Self-service

2Measurement precision

If detecting unit is disposed separately from chuck table to detect cutting blade position, then home position can be determined, but relative shifts or tool wear cause inaccurate home position determination

Engineering Contradiction:

Improvehome position detection accuracyVSAvoiddetection accuracy under relative shift or tool wear

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent introduces light as an intermediary medium between the detection system and the processing tool. The light field serves as a stable reference that is not affected by mechanical relative shifts between the detecting unit and chuck table, providing reliable home position determination even when tools wear or positions shift.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 accurate detection of the distance between the chuck table and processing tools, ensuring high-precision processing capabilities and overcoming issues related to operator skill requirements and tool misalignment or damage.

Implementation Method 1

a chromatic aberration condensing lens for causing light L0 from the broadband light source to form focused spots at different positions on the optical axis depending on wavelengths

Methodology Applied

Scientific EffectChromatic aberration:

Implementation Method 2

a mirror for reflecting light emitted from the broadband light source to travel toward the processing tool

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

a light branching unit for branching reflected light L1 from the processing tool that has been reflected by the mirror and traveled back through the chromatic aberration condensing lens

Methodology Applied

Scientific EffectLight branching:

Implementation Method 4

a position detecting unit for detecting a position of the processing tool on the basis of intensity of reflected light L1 that corresponds to a wavelength of the reflected light branched by the light branching unit

Methodology Applied

Scientific EffectLight intensity detection: Photoelectric Effect

Data Source

PatentUS11919114B2Measuring apparatus for measuring positional relation between a chuck table and a processing tool

Publication Date: 2024.03.05 DISCO CORP

AI summary

A measuring apparatus for measuring positional relation between a chuck table for holding a workpiece thereon and a processing tool for processing the workpiece held on the chuck table. The measuring apparatus includes a broadband light source, a mirror for reflecting light emitted from the broadband light source to travel toward the processing tool, a chromatic aberration condensing lens disposed between the broadband light source and the mirror or between the mirror and the processing tool, a light branching unit branching reflected light from the processing tool that has been reflected by the mirror and traveled back through the chromatic aberration condensing lens, and a position detecting unit detecting the position of the processing tool on the basis of intensity of the reflected light that corresponds to a wavelength of the reflected light branched by the light branching unit.