Multi-Axis Photoelectric Sensor Muting for Variable Workpiece Detection

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Solution Overview

Problem

Existing multiple-optical-axis photoelectric sensors face challenges in efficiently managing the muting state for workpieces of varying shapes and heights, requiring complex installation and adjustments, and struggle to prevent false triggering by non-workpiece objects.

Innovation Solution

A safety management system with two multiple-optical-axis photoelectric sensors, where one sensor acts as a safety management sensor and the other as a muting sensor, using detection-pattern accumulation and control means to match light entrance/obstruction patterns, allowing for automatic adjustment of the muting state based on workpiece patterns, and incorporating detection-pattern accumulation, control, and communication means to manage sensor outputs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a single optical axis photoelectric sensor is used, then the device structure is simple, but the measurement precision and reliability are insufficient due to interference from surrounding objects

Engineering Contradiction:
Improvedetection accuracyVSAvoidsensor structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent divides the detection function into multiple independent optical axes (first, second, and third optical axes) with different detection angles. Each optical axis detects objects from a different direction, allowing the system to distinguish between target objects and surrounding interference objects by comparing detection results across multiple axes, thereby improving measurement precision without requiring a single complex sensor.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from single-axis (one-dimensional) detection to multi-axis (multi-dimensional) detection by introducing detection angles. The first, second, and third optical axes are arranged at different angles relative to the workpiece, adding angular dimensionality to the detection system. This enables the sensor to differentiate objects based on their spatial position and orientation, improving detection accuracy while maintaining relatively simple sensor structures.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If safety management systems rely on manual monitoring, then operational flexibility is maintained, but work efficiency is low and safety risks increase

Engineering Contradiction:
Improvework efficiencyVSAvoidsafety management system
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The safety management system automatically monitors workpiece detection results from multiple optical axes and autonomously determines whether objects are target objects or surrounding objects based on predefined criteria. The system self-manages the comparison of detection data, identification of interference objects, and control signals without requiring manual intervention, thereby improving work efficiency while keeping the system architecture relatively simple through automated decision-making logic.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The system continuously receives detection signals from multiple optical axes, compares results in real-time, and provides feedback control signals to distinguish target objects from surrounding objects. This feedback mechanism enables automatic adjustment and decision-making, improving productivity by eliminating manual monitoring while maintaining system simplicity through rule-based feedback processing.

Inventive Principle:
Principle #23Feedback

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 system simplifies the installation and adjustment of muting sensors, effectively handles workpieces of different shapes and heights, and prevents false triggering by non-workpieces, enhancing safety and operational efficiency.

Implementation Method 1

Multiple-optical-axis photoelectric sensor

Methodology Applied
Scientific EffectPhotoelectric detection: Photoelectric Effect

Data Source

PatentEP2474960B1Multiple-optical-axis photoelectric sensor, and safety management system using same
Publication Date: 2021.05.26 OMRON CORP
  • EP2474960B1 patent drawingFigure 1
  • EP2474960B1 patent drawingFigure 2
  • EP2474960B1 patent drawingFigure 3

AI summary

Disclosed is a safety management system wherein two multiple-optical-axis photoelectric sensors (100, 200) are arranged along a path (L) through which work (W) is conveyed to a danger zone. The downstream sensor (100) is used as a safety management sensor and the upstream sensor (200) is used as a muting sensor. The safety management system includes: detection-pattern accumulation means that, at least while the muting sensor (200) has an optical axis that is blocked, accumulates detection-pattern information that represents patterns of light entrance/obstruction for the optical axes of the sensor (200); and control means that determines whether a change in the accumulated detection-pattern information is matched with a change in pattern of light entrance/obstruction for the optical axes of the safety management sensor (100) while the sensor (100) has an optical axis that is blocked. When determining that the changes are matched with each other, the control means turns output from the safety management sensor (100) on, and when the outputs are not matched, the control means turns output from the safety management sensor (100) off.