Optical Encoder Reflector Design for Displacement Detection

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Solution Overview

Problem

Existing optical encoders for detecting the bending angle of linear power transmission members, such as wires used in manipulators and endoscopes, face challenges in accurately measuring longitudinal displacement and bending direction due to limitations in reflectance patterns and detection mechanisms.

Innovation Solution

An optical encoder system with a reflector having two kinds of reflecting portions with different reflectance, arranged in a predetermined pattern on the linear power transmission member, uses a light source, linear light transmitter, and signal processing mechanism to calculate longitudinal displacement and bending angle based on the intensity and pattern of reflected light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a reflector with two kinds of reflecting portions different in reflectance is used, then measurement precision of longitudinal displacement is improved, but device complexity increases

Engineering Contradiction:

Improvelongitudinal displacement detection accuracyVSAvoidencoder structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The reflector is designed with two kinds of reflecting portions (first and second reflecting portions) that have different reflectances. This local differentiation in reflectance properties allows the light receiving element to detect different light intensities corresponding to different positions of the linear power transmission member, thereby enabling precise measurement of longitudinal displacement without requiring complex external measurement systems.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If light absorbing parts are formed in the optical fiber to detect bending angle, then measurement precision is improved, but device complexity and size increase

Engineering Contradiction:

Improvebending angle detection accuracyVSAvoiddetection sensor structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Instead of forming multiple light absorbing parts within the optical fiber, the invention applies the local quality principle by creating two distinct reflecting portions on the reflector with different reflectances. This approach achieves bending angle detection by measuring changes in reflected light intensity at these differentiated surfaces, avoiding the need to modify the optical fiber structure itself and thereby reducing device complexity.

Inventive Principle:

Principle #3Local quality

3Measurement precision

If multiple light absorbing parts are used in the optical fiber, then detection accuracy is improved, but ease of manufacture deteriorates

Engineering Contradiction:

Improvedisplacement detection accuracyVSAvoidencoder manufacturing simplicity

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

Instead of modifying the optical fiber by adding light absorbing parts (which complicates manufacturing), the invention inverts the approach by placing the reflective structures on the linear power transmission member itself. The two kinds of reflecting portions are formed on the reflector surface, which is easier to manufacture and assemble than modifying the optical fiber, while still achieving the same displacement detection accuracy.

Inventive Principle:

Principle #13The other way round (Inversion)

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 enables precise detection of longitudinal displacement and bending angle, improving the accuracy and reliability of the bending operation system, while reducing the size and complexity of the encoder, and simplifying sterilization and maintenance.

Implementation Method 1

a reflector which is provided on an outer peripheral surface of the linear power transmission member and which is longitudinally movable integrally with the linear power transmission member, the reflector including two kinds of reflecting portions different in reflectance are longitudinally arranged; a light source which radiates light; a linear light transmitter which guides the light from the light source to the reflector and to which reflection light reflected from the reflector is guided

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS8305586B2Optical encoder, bending operation system, and method of detecting displacement of linear power transmission member

Publication Date: 2012.11.06 OLYMPUS CORPORATION(JP)

AI summary

An optical encoder includes a linear power transmission member which moves longitudinally, a reflector which is provided on an outer peripheral surface of the linear power transmission member and which is longitudinally movable integrally with the linear power transmission member, the reflector including two kinds of reflecting portions different in reflectance are longitudinally arranged, and a light source which radiates light. Further, the optical encoder includes a linear light transmitter which guides the light from the light source to the reflector and to which reflection light reflected from the reflector is guided, and a calculation mechanism configured to calculate a longitudinal displacement of the reflector on the basis of an intensity of the reflection light from the reflector which is guided via the linear light transmitter.