Optical Sensor Code Strip Motion Detection via Beam Deflection

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Solution Overview

Problem

Existing systems for determining the movement of a code strip relative to an optical sensor are complex and prone to errors, particularly when detecting fast relative movements, and require individually recognizable markers.

Innovation Solution

A system with a controllable beam deflection device that moves a light spot back and forth along the code strip, using the time dependence of detection signals from markers to determine movement, allowing for robust and error-resistant detection without the need for individually recognizable markers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If individual marker recognition is used to determine movement, then position can be determined, but the system becomes complex and error-prone

Engineering Contradiction:
Improveposition determinationVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The invention extracts the essential information needed for movement detection (modulation frequency and phase) while discarding the complex requirement for individual marker recognition. By focusing only on the temporal modulation pattern of the detection signal rather than identifying specific markers, the system achieves position and movement determination with significantly reduced complexity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the measurement parameter from spatial marker identification to temporal signal analysis. Instead of determining position by recognizing individual markers in space, the system determines movement by analyzing the frequency and phase of temporal modulations in the detection signal, thereby simplifying the measurement approach

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If individual marker recognition is used, then position can be determined, but the system is prone to errors

Engineering Contradiction:
Improveposition determinationVSAvoiderror resistance
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The invention extracts only the essential temporal modulation characteristics (frequency and phase) from the detection signal, eliminating the need for complex individual marker recognition that introduces errors. This extraction approach focuses on robust temporal patterns that are less susceptible to recognition errors

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses the modulation frequency and phase as feedback parameters to continuously track movement. By monitoring how the temporal characteristics of the detection signal change over time, the system can reliably determine movement without relying on error-prone individual marker identification

Inventive Principle:
Principle #23Feedback

3Measurement precision

If traditional optical sensing is used, then position can be detected, but fast relative movements cannot be detected reliably

Engineering Contradiction:
Improvemovement detectionVSAvoidrelative movement speed
Core Design Contradiction:
Measurement precisionVSSpeed

Solution Approach 1:

The invention changes from spatial measurement parameters to temporal measurement parameters. By analyzing the frequency and phase of temporal modulations in the detection signal, the system can capture fast movements that would be too rapid for traditional frame-based or position-based optical sensing methods

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention replaces traditional mechanical or frame-based position detection with optical modulation analysis. The controllable beam deflection device sweeps the light spot across the code strip, and the temporal modulation frequency of the reflected light directly encodes the relative movement speed, enabling reliable detection of fast movements

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

4Measurement precision

If complex marker recognition systems are used, then movement can be determined, but implementation becomes difficult

Engineering Contradiction:
Improvemovement determinationVSAvoidimplementation simplicity
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The invention extracts only the necessary temporal modulation information from the detection signal, eliminating the need for complex marker recognition algorithms and individual marker design. This simplification makes the system easier to manufacture and implement while maintaining accurate movement determination

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

Instead of using complex markers to encode position information that must be decoded, the invention inverts the approach by using the natural temporal modulation of reflected light from simple markers as the measurement signal. The modulation frequency and phase directly provide movement information without requiring complex decoding

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

The solution enables simple and inexpensive implementation, capable of detecting fast movements with high reliability, suitable for industrial environments, and can determine speed and position with high accuracy.

Implementation Method 1

Detection light emitted by the code strip as a result of irradiation with the light spot

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP4478244A1System and method for determining a motion of a code strip relative to an optical sensor
Publication Date: 2024.12.18 PEPPERL & FUCHS SE
  • EP4478244A1 patent drawingFigure 1
  • EP4478244A1 patent drawingFigure 2~2b
  • EP4478244A1 patent drawingFigure 3~3c

AI summary

The invention relates to a system for determining the movement of a code strip relative to an optical sensor, comprising the code strip having a plurality of markers along a direction of extension, and the optical sensor comprising the following components: at least one light transmitter for sending a beam of light as at least one luminous spot onto the code strip, at least one detector for detecting detection light emitted by the code strip as a result of irradiation with the luminous spot, and a control and evaluation unit for controlling the at least one transmitter and for evaluating a detection signal detected by the at least one detector.The system is characterized in that a controllable beam deflection device is provided for deflecting the transmitted light beam, and that the control and evaluation unit is configured to control the beam deflection device such that the luminous spot on the code strip is moved back and forth in its direction of extension, and to determine a movement of the code strip relative to the optical sensor based on a time dependence of the detected signal caused by the markers. The invention also relates to a method for determining a movement of a code strip relative to an optical sensor.