Rotary Scale Angle Detection with Reduced Sensor Count

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Solution Overview

Problem

Conventional measuring devices that detect rotation angles and speeds with multiple detection units increase the number of components and current consumption, compromising measurement accuracy and efficiency.

Innovation Solution

A measuring device with a rotary scale featuring two types of patterns and detection sections, where the number of second pattern detection sections is less than the first, allowing for absolute angle calculation using a calculator that processes readings from both sets of detection sections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If multiple detection sections are arranged around the rotation axis to improve measurement accuracy, then measurement precision is improved, but device complexity and current consumption increase

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidnumber of components

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the detection system into two functional groups: first pattern detection sections that read patterns from the first scale, and second pattern detection sections that read patterns from the second scale. This segmentation allows different detection sections to serve different purposes, with the second pattern detection sections providing reference information for absolute angle calculation while the first pattern detection sections providing detailed position information.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different detection strategies to different parts of the system. The first scale has patterns with a first period used for general position detection, while the second scale has patterns with a second period (different from the first) used for absolute angle reference. The detection sections are selectively arranged to read from appropriate scales based on their specific functional requirements.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If multiple detection sections are arranged around the rotation axis to improve measurement accuracy, then measurement precision is improved, but current consumption increases

Engineering Contradiction:

Improvemeasurement accuracyVSAvoidcurrent consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent uses a selective arrangement where the number of second pattern detection sections is intentionally made less than the number of first pattern detection sections. The second pattern detection sections provide sufficient reference information for absolute angle calculation without the need for complete circumferential coverage, thereby reducing the total number of detection sections and current consumption while maintaining measurement accuracy.

Inventive Principle:

Principle #16Partial or excessive action

3Adaptability or versatility

If two types of patterns with different periods are used on the rotary scale, then absolute angle identification capability is improved, but device complexity increases

Engineering Contradiction:

Improveabsolute angle identification capabilityVSAvoidscale structure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The rotary scale is designed with two types of patterns (first patterns with first period and second patterns with second period) that serve multiple functions. The first patterns enable general position detection, while the second patterns enable absolute angle reference. Both pattern types are integrated into a single rotary scale structure, allowing the scale to perform multiple measurement functions simultaneously without requiring separate scales.

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

Reduces the number of components and current consumption while maintaining high measurement accuracy by utilizing fewer inner detection heads for absolute angle calculation, improving calculation accuracy and reducing errors.

Implementation Method 1

a plurality of first pattern detection sections that are arranged around the rotation axis, each of which faces the first scales and reads at least a part of the plurality of first patterns

Methodology Applied

Scientific EffectOptical detection: Photoelectric Effect

Implementation Method 2

a second detection section that faces the second scale and reads at least a part of the plurality of second patterns

Methodology Applied

Scientific EffectOptical detection: Photoelectric Effect

Data Source

PatentUS20240337474A1Measuring device and absolute angle identification method

Publication Date: 2024.10.10 MITUTOYO CORP

AI summary

A measuring device includes a first scale provided on a rotary scale, arranged around an rotation axis of the rotary scale, and having first patterns arranged along a circumferential direction, a second scale provided on the rotary scale, arranged around the rotation axis, and having a plurality of second patterns arranged along the circumferential direction, first pattern detection sections arranged around the rotation axis, a second detection section that faces the second scale and reads at least a part of the plurality of second patterns, and a calculator configured to identify an absolute angle of the rotary scale, on a basis of a reading result of the first pattern detection sections and a reading result of the second pattern detection section. A number of the second pattern detection section is less than a number of the plurality of first pattern detection sections.