AC Voltage Locating Device Common-Mode Noise Suppression

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Solution Overview

Problem

Existing AC voltage locating devices face challenges in accurately determining the position of concealed objects with high sensitivity and minimal environmental dependency, particularly in suppressing common-mode noise and efficiently processing AC voltage signals.

Innovation Solution

The proposed AC voltage locating device incorporates multiple receiving means and amplifier circuits that amplify differences between coupling signals and a reference signal, generating square-wave output signals for easy evaluation, along with an evaluation device to determine phase angles and locating directions, and filter means to suppress high-frequency interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If amplifier circuits amplify the difference between coupling signals and reference signal, then sensitivity is improved, but environmental dependency increases

Engineering Contradiction:
ImprovesensitivityVSAvoidenvironmental dependency
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent converts the harmful common-mode environmental interference into a useful reference signal. By capturing the environmental dependency through the reference signal and subtracting it from the coupling signals, the system eliminates the harmful interference while preserving the useful locating information, thus improving sensitivity without actual environmental dependency.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The reference signal acts as an intermediary that mediates between the coupling signals and the environmental interference. It captures the environmental dependency and transmits this information to the amplifier circuits for subtraction, thereby eliminating the harmful effects without directly affecting the locating function.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If multiple amplifier circuits are used to process coupling signals, then locating accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvelocating accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the signal processing function into multiple independent amplifier circuits, each handling specific coupling signals. This segmentation allows parallel processing of different signal paths, improving locating accuracy through comprehensive signal analysis while maintaining modular simplicity that prevents excessive device complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The amplifier circuits are designed with universal functionality to process multiple types of coupling signals (inductive and capacitive) through the same difference amplification mechanism. This multi-functionality reduces the need for specialized circuits for each signal type, thereby improving locating accuracy without proportionally increasing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If difference amplification is applied to suppress common-mode noise, then signal quality is improved, but circuit design complexity increases

Engineering Contradiction:
Improvesignal qualityVSAvoidcircuit design complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The difference amplification circuit converts the harmful common-mode noise into a subtracted term that eliminates interference. By amplifying only the differential signal component and rejecting the common-mode component, the circuit improves signal quality while the standardized difference amplification topology keeps circuit design complexity manageable.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The circuit changes the parameter of signal amplification by selectively amplifying only the differential component while rejecting common-mode signals. This parameter-selective amplification improves signal quality by suppressing noise, and the use of standard difference amplifier configurations maintains reasonable circuit design complexity.

Inventive Principle:
Principle #35Parameter changes

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 configuration enhances sensitivity, reduces environmental dependency, and allows for simple design while achieving effective common-mode suppression and easy signal evaluation, enabling precise locating with minimal design effort.

Implementation Method 1

a signal that is transmitted from the concealed locating object through the workpiece to the locating device by means of inductive and/or advantageously capacitive coupling

Methodology Applied
Scientific EffectInductive coupling: Electromagnetic Induction

Implementation Method 2

a signal that is transmitted from the concealed locating object through the workpiece to the locating device by means of inductive and/or advantageously capacitive coupling

Methodology Applied
Scientific EffectCapacitive coupling: Capacitance

Data Source

PatentEP3060945B1Locating device
Publication Date: 2021.06.09 ROBERT BOSCH GMBH
  • EP3060945B1 patent drawingFigure 1
  • EP3060945B1 patent drawingFigure 2
  • EP3060945B1 patent drawingFigure 3

AI summary

The invention relates to a positioning device with an AC voltage positioning device (12) which has a first receiving means (14) provided for receiving a first coupling signal (16) from a positioning object (18), at least one second receiving means (20, 22) provided for receiving at least one second coupling signal (24, 26) from the positioning device (18), and at least one first amplifier circuit (28) that amplifies a difference between the first coupling signal (16) and a reference signal (30) in at least one operating state. According to the invention, the AC voltage positioning device (12) has at least one second amplifier circuit (32, 34) which amplifies a difference between the first coupling signal (16) and the second coupling signal (24, 26) in at least one operating state.