Optical Encoder Layout for Precise Rotary Plate Eccentricity Detection

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Solution Overview

Problem

Conventional encoders are unable to precisely detect the eccentricity of a rotary plate relative to a detection target.

Innovation Solution

An encoder design that includes a rotary plate with annular patterns and light-receiving regions, along with a light emitter and receiver, calculates the eccentricity of the rotary plate relative to the detection target using specific signal processing to determine the eccentric phase and amount, enabling precise detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional encoders are used to detect rotation, then basic rotational information can be obtained, but precise detection of the eccentricity of the rotary plate relative to the detection target is not achieved

Engineering Contradiction:
Improveeccentricity detection precisionVSAvoideccentricity information loss
Core Design Contradiction:
Measurement precisionVSLoss of information

Solution Approach 1:

The light receiver is divided into multiple light-receiving regions (first light-receiving region and second light-receiving region) that are arranged side by side in a direction intersecting the rotation direction. This segmentation allows different regions to detect light at different positions, enabling the system to calculate eccentricity by comparing the differences in light reception among the segmented regions.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Light serves as an intermediary between the rotary plate and the light receiver. The light emitted by the emitter reflects off the rotary plate and reaches different light-receiving regions, carrying information about the plate's position and eccentricity. By measuring the light intensity distribution across multiple receiving regions, the system can indirectly detect eccentricity without direct mechanical contact.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If multiple light-receiving regions are used to detect eccentricity, then measurement precision improves, but device complexity increases

Engineering Contradiction:
Improveeccentricity detection precisionVSAvoidencoder structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

Multiple light-receiving regions are integrated onto a single substrate rather than being separate components. This merging approach maintains the functional benefits of having multiple detection regions while reducing overall device complexity and simplifying the encoder structure.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The light receiver with multiple light-receiving regions serves multiple functions: it detects both the rotational position and the eccentricity of the rotary plate simultaneously. This multi-functionality eliminates the need for separate detection mechanisms, thereby reducing device complexity while maintaining high measurement precision.

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

The encoder achieves precise detection of the eccentricity of the rotary plate, allowing for accurate position determination even when eccentric, and is compact and cost-effective due to the arrangement of light-receiving regions on a single substrate.

Implementation Method 1

an emitter 40 that emits light

Methodology Applied
Scientific EffectLight emission: Light

Implementation Method 2

a rotary plate 20 that rotates and includes an annular region 26 that reflects the light emitted from the emitter 40

Methodology Applied
Scientific EffectLight reflection: Reflection

Implementation Method 3

a light receiver 50 that receives light emitted from the emitter 40 and arriving via the annular region 26

Methodology Applied
Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentEP4459236B1Encoder and attachment method
Publication Date: 2026.04.08 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP4459236B1 patent drawingFigure 1
  • EP4459236B1 patent drawingFigure 2
  • EP4459236B1 patent drawingFigure 3

AI summary

An encoder (10) includes: an emitter (40) that emits light; a rotary plate (20) that rotates and includes an annular region (26) that reflects the light emitted from the emitter (40), the annular region (26) being provided surrounding a rotation axis (A) of the rotary plate (20); and a light receiver (50) that receives light emitted from the emitter (40) and arriving via the annular region (26). The light receiver (50) includes: a first set that includes a first light-receiving region (55) and a second light-receiving region (56) that are arranged side by side in a first direction (E) intersecting a rotation direction (C) of rotary plate (20); and a second set that includes a third light-receiving region (57) and a fourth light-receiving region (58) that are arranged side by side in a second direction (F) intersecting the rotation direction (C) and that is provided side by side with the first set in the rotation direction (C).