Photoelectric Encoder Scale With Plated Metal Gratings

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Solution Overview

Problem

Existing photoelectric encoder technologies face high manufacturing costs, difficulty in forming gratings with high accuracy, and reduced detection accuracy due to low reflection light quantity.

Innovation Solution

A photoelectric encoder scale with a base member having a blackened layer formed by surface oxidation, where metal gratings are formed through plating at a prescribed pitch, acting as a light reflection film, and a manufacturing method involving surface treatment and plating to create high-adhesion, uniform-thickness metal gratings.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a film forming apparatus is used for grating formation, then the grating can be formed on the scale, but the manufacturing cost becomes very high due to the requirement of a vacuum chamber

Engineering Contradiction:
Improvegrating formation capabilityVSAvoidmanufacturing cost
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the vacuum-based film forming apparatus with a plating process that can be performed in a conventional manufacturing environment. Instead of using complex vacuum deposition equipment to form the light reflection film, the invention uses electroplating or chemical plating methods to deposit metal gratings on the blackened layer, thereby eliminating the need for expensive vacuum chambers while achieving the same grating formation function

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the formation method parameter from vacuum deposition to plating process. By altering the fundamental parameter of how the light reflection film is formed (from physical vapor deposition in vacuum to electrochemical plating in solution), the invention achieves grating formation with much lower manufacturing costs and simpler equipment requirements

Inventive Principle:
Principle #35Parameter changes

2Manufacturing precision

If conventional methods are used for grating formation, then the process can be completed, but it is difficult to form a grating with high accuracy

Engineering Contradiction:
Improvegrating accuracyVSAvoidprocess complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary surface oxidation treatment to the base member before plating to create a blackened layer with controlled properties. This preliminary action ensures that the subsequent plating process produces gratings with high accuracy and uniformity, as the pre-treated surface provides consistent nucleation sites for metal deposition

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The blackened layer formed by surface oxidation acts as an intermediary between the base member and the metal grating layer. This intermediate layer improves the adhesion of the plating and provides a uniform surface that enables high-accuracy grating formation, solving the problem of achieving consistent and precise grating structures

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of manufacture

If the reflection light quantity is reduced, then the manufacturing process can be simplified, but the detection accuracy is lowered

Engineering Contradiction:
Improveprocess simplicityVSAvoiddetection accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent creates a composite structure consisting of a blackened layer (from surface oxidation) combined with a metal grating layer (from plating). This composite material structure provides both the manufacturing simplicity of conventional processes and the high reflection light quantity needed for accurate detection, as the metal grating layer on the blackened substrate offers superior optical properties compared to single-layer structures

Inventive Principle:
Principle #40Composite materials

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

The solution results in a low-cost, high-accuracy photoelectric encoder scale with improved adhesion and thickness distribution uniformity, reducing manufacturing costs and enhancing grating shape accuracy.

Implementation Method 1

a base member having a blackened layer formed by surface oxidation on a surface of the base member

Methodology Applied
Scientific EffectSurface oxidation: Oxidation

Implementation Method 2

metal gratings which are formed on the blackened layer of the base member by plating

Methodology Applied
Scientific EffectPlating: Electroplating

Data Source

PatentEP2597431B1Scale of photoelectric encoder and manufacturing method of the same
Publication Date: 2019.04.24 MITUTOYO CORP
  • EP2597431B1 patent drawingFigure 1~2B
  • EP2597431B1 patent drawingFigure 3A~3D
  • EP2597431B1 patent drawingFigure 4A~5

AI summary

A scale of a photoelectric encoder includes a base member (11) which is conductive and has a light reflection surface, and light absorptive black gratings (12) which are arranged at a prescribed pitch on the base member.