Piezo Cable Sensor for Furniture Anti-Trap Protection
Solution Overview
Problem
Existing electromotive furniture drives face challenges in reliable anti-trap protection due to interference from environmental conditions, particularly with capacitive and ultrasonic sensors, which can lead to false detections and inadequate monitoring of small objects or animals.
Innovation Solution
An electromotive furniture drive equipped with a monitoring device featuring a piezo cable sensor unit that evaluates signal curves to distinguish between actual pinch events and disturbances, allowing for improved operational safety and reliability by slowing, stopping, or reversing the drive in case of trapping events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive sensors are used for pinch protection, then detection capability is provided, but false detections occur due to environmental conditions
Solution Approach 1:
The patent replaces capacitive sensors (electrical field-based) with a piezoelectric cable sensor that detects mechanical deformation directly. When the cable is pinched or deformed, it generates an electrical signal through the piezoelectric effect, providing reliable mechanical contact detection without environmental interference.
Solution Approach 2:
The piezoelectric cable acts as a mechanical intermediary between the pinch event and the detection system. The cable's physical deformation mediates the detection process, converting mechanical stress into an electrical signal that accurately indicates a true pinch condition.
2Area of stationary object
If ultrasonic sensors are used for monitoring larger areas, then coverage is improved, but detection at smaller distances is limited
Solution Approach 1:
Instead of using ultrasonic sensors for both large-area monitoring and close-distance detection, the patent applies piezoelectric cable sensors specifically at critical pinch points where close-distance detection is needed. This localized application provides precise detection exactly where required.
3Adaptability or versatility
If metal fittings are used as antenna for capacitive sensing, then sensor function is integrated, but consistent results are not achieved
Solution Approach 1:
The patent replaces the capacitive sensing approach using metal fittings as antennas with a piezoelectric cable-based mechanical sensing system. This substitution eliminates the environmental sensitivity of capacitive fields while maintaining integration into the furniture structure.
4Reliability
If piezoelectric cable is used for detection, then operational safety is improved, but device complexity increases
Solution Approach 1:
The piezoelectric cable serves multiple functions: it acts as both the structural element and the sensing element. The same cable that provides mechanical support or connection also detects pinch events through deformation, eliminating the need for separate sensing components.
Solution Approach 2:
The piezoelectric cable is self-sensing; it automatically generates an electrical signal when deformed by a pinch event. No additional power supply, electronics, or complex processing is needed at the sensing location—the cable itself performs the detection function.
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
Enhances operational safety and reliability by accurately detecting pinch events and preventing damage to people, animals, and objects, while adapting to complex furniture geometries and reducing interference from external fields.
Implementation Method 1
the sensor unit is designed as a piezoelectric cable or includes a piezoelectric cable
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to an electric motor-driven furniture drive mechanism (4) for adjusting moveable components of an item of furniture (1), in particular functional furniture, comprising at least one electric motor-driven adjustment drive mechanism (4a, 4b) having a control device (5) and at least one operating device (6), a monitoring device (7) having at least one detection device (10) for monitoring at least one monitoring region (9) and forming an anti-trap protection system for the associated item of furniture (1). The electric motor-driven furniture drive mechanism (4) is characterised in that the at least one detection device (10) has at least one sensor unit (11) which is in the form of or comprises a piezo cable. The invention also relates to an item of furniture having an electric motor-driven furniture drive mechanism (4).