Light Time-of-Flight Sensor Using Single-Photon Diode Matrix

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Solution Overview

Problem

Current direct light transmission systems for distance measurement in safety technology are complex, have limited dynamic range, require high voltage and expensive components, and are prone to errors due to ambiguity and mutual influence, making them unsuitable for reliable machine safety applications.

Innovation Solution

A light-cycle sensor with a matrix of single-photon diodes, a measurement generator, and a control and evaluation unit, utilizing a test transmitter to activate single-photon diodes and collect measured values in a histogram for accurate distance measurement, which realizes direct photon-to-digital conversion and provides excellent dynamic range and sensitivity, enabling precise light-time determination and error detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If avalanche photodiodes with transimpedance amplifiers are used for direct light transmission measurement, then measurement capability is achieved, but dynamic range is limited and high voltage generation is required

Engineering Contradiction:
Improvedistance measurement capabilityVSAvoidhigh voltage generation and special components
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses standard photodiodes instead of specialized avalanche photodiodes, creating a simplified copy of the measurement function that eliminates the need for high voltage generation while maintaining measurement capability through alternative signal processing

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent changes the operating parameters by using standard photodiodes with conventional voltage levels instead of avalanche photodiodes requiring high voltage, thereby simplifying the system while achieving comparable measurement results through different operational conditions

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If phase measurement systems are used for indirect runtime measurement, then integration is simpler and scaling capability is good, but ambiguity and mutual influence cause measurement errors

Engineering Contradiction:
Improveintegration simplicity and scaling capabilityVSAvoidmeasurement accuracy due to ambiguity and mutual influence
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces the phase measurement method with direct time-of-flight measurement using standard photodiodes, substituting a more reliable but traditionally more complex measurement approach that eliminates ambiguity and mutual influence errors while maintaining integration feasibility

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

3Measurement precision

If separate receivers with avalanche photodiodes and time measuring units are used for direct light transmission, then distance measurement is achieved, but space requirement is high and components are expensive

Engineering Contradiction:
Improvedistance measurement capabilityVSAvoidspace requirement for components
Core Design Contradiction:
Measurement precisionVSArea of stationary object

Solution Approach 1:

The patent merges the functions of light detection and time measurement into a single integrated unit using standard photodiodes, eliminating the need for separate avalanche photodiode receivers and time measuring units, thereby reducing space requirements and component costs while maintaining measurement precision

Inventive Principle:
Principle #5Merging (Combining)

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 provides a highly accurate and reliable distance measurement system with improved dynamic range and sensitivity, capable of detecting even low-level signals, and ensures safety integrity by self-monitoring and error detection, suitable for machine safety applications.

Implementation Method 1

at least one receiving element (3) from a matrix (4) of single-photon diodes (5)

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP3543734B1Light runtime sensor
Publication Date: 2021.11.24 SICK AG
  • EP3543734B1 patent drawingFigure 1
  • EP3543734B1 patent drawingFigure 2
  • EP3543734B1 patent drawingFigure 3

AI summary

Light time-of-flight sensor (1) with a measuring path (2) for measuring a light time-of-flight, wherein the measuring path (2) has at least one receiving element (3) consisting of a matrix (4) of single-photon avalanche diodes (5), at least one measuring element generator (6) connected to the matrix (4) and at least one measuring element collector (7) connected to the measuring element generator (6), wherein at least one control and evaluation unit (8) is provided, wherein ambient light and/or at least one test transmitter (9) is provided for testing and/or functional testing of the measuring path (2).