Laser Scanner Amplifier Segmentation for Dynamic Range

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Solution Overview

Problem

Conventional laser scanners face challenges in accurately measuring distances due to high dynamic range signal power variations, leading to signal overload, distortion, and increased measurement errors, especially in high-contrast environments and fast scanning movements.

Innovation Solution

The solution involves dividing the dynamic range into separate amplification paths for strong and weak signals, allowing for distortion-free evaluation and precise measurement by using a sensitive and insensitive amplification path, with the sensitive path handling weak signals and the insensitive path handling strong signals, and combining the signals for digital conversion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single amplifier is used to handle the entire dynamic range of received signals, then the device complexity is reduced, but the measurement precision deteriorates due to signal overload and distortion in high-contrast environments

Engineering Contradiction:
Improveamplifier structureVSAvoiddistance measurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The received signal path is divided into multiple amplification paths (first amplification path with lower gain and second amplification path with higher gain). Each path processes signals within its optimal dynamic range, preventing overload distortion while maintaining sensitivity for weak signals. This segmentation resolves the contradiction by allowing accurate measurement across the full dynamic range without requiring a single complex high-performance amplifier.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If the amplifier gain is increased to detect weak received signals, then the measurement precision for weak signals improves, but the reliability deteriorates due to signal overload and distortion when strong signals are received

Engineering Contradiction:
Improveweak signal detection capabilityVSAvoidsignal evaluation reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The system dynamically selects which amplification path to use based on the strength of the received signal. A selection unit determines whether the first or second amplification path should process the signal, switching between fixed gain values adaptively. This dynamic approach ensures that weak signals are amplified sufficiently for detection while strong signals are processed with appropriate gain to avoid overload, maintaining both precision and reliability.

Inventive Principle:
Principle #15Dynamics

3Adaptability or versatility

If actuators are used to adjust the amplifier gain dynamically, then the adaptability to different signal strengths improves, but the device complexity and response time worsen due to mechanical adjustment limitations

Engineering Contradiction:
Improvegain adaptation capabilityVSAvoidactuator control system
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical actuator-based gain adjustment with electronic signal routing. Instead of physically adjusting amplifier gain using actuators, the system uses a selection unit to electronically switch between multiple fixed-gain amplification paths. This substitution eliminates mechanical complexity and response time limitations while maintaining adaptability to different signal strengths through electronic control.

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

4Ease of manufacture

If a transimpedance amplifier is used after the light receiver, then the ease of manufacture improves, but the measurement precision deteriorates due to signal overload and broadening that makes evaluation difficult or impossible

Engineering Contradiction:
Improvereceiver implementationVSAvoidsignal evaluation accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The transimpedance amplification stage is segmented into multiple parallel paths with different gain characteristics. The first transimpedance amplifier handles strong signals with lower gain, while the second transimpedance amplifier handles weak signals with higher gain. This segmentation prevents signal overload and broadening in the overall system while maintaining ease of manufacture by using standard transimpedance amplifier designs in each path.

Inventive Principle:
Principle #1Segmentation

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

This approach enhances measurement accuracy, enables evaluation of signals over a wide dynamic range, and suppresses interference, allowing for precise distance measurement even in challenging conditions like fog or dirty windshields, without significant distortion.

Implementation Method 1

a light receiving element (20) which converts the received light into an electrical signal

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentEP2182377B1Laser scanner to measure distance
Publication Date: 2012.09.19 SICK AG
  • EP2182377B1 patent drawingFigure 1~2
  • EP2182377B1 patent drawingFigure 3
  • EP2182377B1 patent drawingFigure 4~5

AI summary

The scanner has a light receiving element (20) e.g. photodiode, for receiving a reception signal, and an evaluation unit (32) for determining distance at a running time of a light signal. Amplifiers (24, 26) are provided for a reception signal. A sensitive amplifying path is provided with the amplifiers, respectively. A receiving signal dividing element (22) supplies the receiving signal in parallel to the amplifying paths, so that the receiving signal within a dynamic region exceeding the amplifiers is amplified. The receiving element converts received light into a photoelectric current (I). An independent claim is also included for a method for detecting distance by a laser scanner.