Optical Sensor Signal Buffering for Precision Object Detection

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Solution Overview

Problem

Current sensors in processing machines lack precision in detecting object position due to variations in optical properties of materials, leading to increased jitter and reduced processing speed, despite the need for precise and timely detection to optimize throughput.

Innovation Solution

A sensor with a light receiver, evaluation unit, and timer that stores signal levels to determine object detection time accurately, allowing for precise object positioning and synchronization with external systems, enabling more precise and consistent detection across different materials.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If threshold-based detection is used to determine object presence, then detection simplicity is maintained, but detection precision deteriorates due to variations in optical properties of different materials

Engineering Contradiction:
Improvedetection simplicityVSAvoiddetection precision
Core Design Contradiction:
Ease of operationVSMeasurement precision

Solution Approach 1:

The sensor stores multiple signal levels in a buffer memory before threshold comparison, preparing data in advance to enable precise retroactive time determination. This preliminary data collection allows the system to achieve high precision without complex real-time processing during threshold evaluation.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The sensor collects more signal data than immediately necessary by storing multiple signal levels in the buffer, using excessive data collection to ensure precise time determination can be made retroactively, thereby resolving the precision-simplicity contradiction.

Inventive Principle:
Principle #16Partial or excessive action

2Productivity

If processing speed is increased to improve productivity, then throughput increases, but position precision deteriorates due to slip and tolerances

Engineering Contradiction:
Improvethroughput speedVSAvoidposition precision
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The precise object detection time determined from stored signal levels provides accurate feedback to the control system, enabling real-time compensation for position deviations caused by high-speed conveying, thus maintaining precision at high throughput speeds.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent replaces mechanical position measurement methods with optical signal analysis, using the light receiver and buffer memory system to determine position based on signal characteristics rather than mechanical encoders, thereby achieving higher precision at increased speeds.

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

3Loss of time

If early object detection is implemented to reduce processing time, then throughput increases, but detection accuracy deteriorates due to signal variability

Engineering Contradiction:
Improveprocessing timeVSAvoiddetection accuracy
Core Design Contradiction:
Loss of timeVSMeasurement precision

Solution Approach 1:

The buffer memory continuously stores signal levels before threshold triggering occurs, preparing detection data in advance. This allows the system to detect objects earlier while maintaining accuracy by retroactively analyzing the stored signal curve to determine the precise detection moment.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system creates a temporal copy of the signal curve by storing multiple signal levels in the buffer, allowing precise time determination to be made after the fact rather than requiring immediate accurate detection, thus enabling both early detection and high accuracy.

Inventive Principle:
Principle #26Copying

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 sensor achieves reduced position errors and increased processing speed by determining object detection time from stored signal values, allowing for tighter object spacing and improved throughput without compromising accuracy.

Implementation Method 1

at least one light receiver (20) for detecting a received signal (E) dependent on the presence of an object (B)

Methodology Applied
Scientific EffectOptical detection: Reflection

Data Source

PatentEP2940488B1Device and method for optically detecting an object
Publication Date: 2016.05.18 SICK AG
  • EP2940488B1 patent drawingFigure 1
  • EP2940488B1 patent drawingFigure 2

AI summary

The invention relates to an optical sensor (B) for detecting an object within a detection range. The sensor comprises a receiver (20) for detecting a received signal dependent on the presence of the object, an evaluation unit (28) for evaluating the received signal and outputting a binary object detection signal, a sensor-internal timer (30) for determining an object detection time, a synchronization input (33) for receiving a synchronization signal to synchronize the timer with an external system time, and an output (26) for outputting the binary object detection signal and the associated object detection time.To enable a further increase in precision and a further time saving, it is proposed that the evaluation unit has a memory (32) for storing received signal levels at times specified by the timer and a time determination unit (34) to subsequently determine the object detection time from the stored values ​​and the specified times after the received signal has exceeded a threshold value.