Redundant Touch Sensor Electrodes for Power Tool Safety
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Solution Overview
Problem
Existing safety measures for electrical devices, such as lawnmowers and power tools, lack redundancy and are susceptible to wear and interference, potentially compromising safety and operational reliability.
Innovation Solution
The implementation of a safety system with at least two spaced-apart grip areas on a handle, each equipped with touch sensor modules having two sensor electrodes connected to a redundant security system. This system requires the operator to touch at least one of the sensor electrodes to activate and maintain the device, with logical OR and NAND connections ensuring safe operation and resistance to interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single sensor electrode is used for safety control, then the device can be operated simply, but the safety system lacks redundancy and is susceptible to wear and interference
Solution Approach 1:
The safety system is segmented into multiple independent sensor electrodes (at least two spaced-apart electrodes per gripping area) instead of using a single electrode. This segmentation provides redundancy so that if one electrode fails or is interfered with, the other electrodes can still detect the operator's presence and maintain safe operation.
Solution Approach 2:
The patent implements beforehand cushioning by creating a redundant sensor electrode system that anticipates potential failures or interference. The multiple electrodes are positioned and configured to ensure that even if one electrode is compromised, the safety function remains intact, cushioning against future safety issues.
2Reliability
If multiple sensor electrodes with redundant connections are implemented, then resistance to interference and wear is improved, but the device complexity increases
Solution Approach 1:
Each gripping area is equipped with its own touch sensor modules having at least two sensor electrodes, creating local redundancy at each interaction point. This local quality approach ensures that interference or wear at one location does not compromise the overall safety system, as other gripping areas maintain their sensing capability.
Solution Approach 2:
The safety system continuously monitors the state of multiple sensor electrodes and uses logical evaluation (OR and NAND connections) to determine operator presence. This feedback mechanism allows the system to adapt to electrode failures or interference by relying on the state of other electrodes, maintaining reliable operation despite increased complexity.
3Ease of operation
If touch sensor modules with multiple electrodes are used in each gripping area, then safe operation is ensured through redundancy, but the handling complexity increases
Solution Approach 1:
Multiple sensor electrodes within each gripping area are merged into a single touch sensor module assembly that functions as one integrated safety control unit. The electrodes are electrically connected in parallel configurations with logical OR and NAND connections, allowing them to work together as a unified system rather than separate controls, simplifying the operator's interaction while maintaining redundancy.
Solution Approach 2:
The touch sensor modules with multiple electrodes serve multiple functions: they detect operator presence, provide redundant safety monitoring, and can identify which specific gripping area is being used. This multi-functionality allows the system to maintain simple operation while achieving enhanced safety through redundancy.
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 enhances handling ease, longevity of the safety system, and operational reliability by providing redundancy against sensor electrode failures and interference, ensuring safe operation and high resistance to electromagnetic and high-frequency interference.
Implementation Method 1
each with at least one touch sensor module (52), each touch sensor module (52) having at least two sensor electrodes (64, 66), each sensor electrode (64, 66) being electrically connected to the safety system (54)
Data Source
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AI summary
The invention relates to an electric appliance (10) having at least one handle (28) for the safe guidance of the electric appliance (10) by an operator and having a safety system (54), wherein at least two grip areas (30) are provided on the handle (28) spaced apart from each other, each having at least one touch sensor module (52). According to the invention, each touch sensor module (52) has at least two sensor electrodes (64, 66), which are each electrically connected to the safety system (54), and the safety system (54) is designed in such a manner that the operator must touch at least one of the first and at least one of the second sensor electrodes (64, 66) of the touch sensor modules (52) with at least one part of the body, more particularly with a part of at least one hand, for safe operation of the electric appliance (10). The invention further relates to a method for operating an electric appliance (10) by an operator wherein, in a first step (128), the operator must press an electromechanical button (94) before starting the electric appliance (10) to supply the safety system (54) and the touch sensor modules (52) of the electric appliance (10) with power (130).