Electromotive Furniture Pinch Detection Using Reflected Light
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Solution Overview
Problem
Existing electromotive adjustment devices for furniture lack cost-effective and easily retrofittable safety solutions to prevent pinching injuries, as they rely on expensive switching strips and are not suitable for devices already in operation.
Innovation Solution
An optical safety system using a light transmitter and receiver arranged in a housing coupled with the furniture part, detecting deformations through changes in light intensity and converting these signals to control the drive motor, allowing for contactless and inexpensive retrofitting of existing devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If switching strips are used for safety detection, then pinching protection is achieved, but the cost increases significantly
Solution Approach 1:
The patent replaces the mechanical contact-based switching strip system with an optical detection system using light transmitters and receivers. This substitution eliminates the need for physical contact while achieving the same safety function, thereby reducing cost and improving reliability simultaneously.
Solution Approach 2:
The patent introduces light as an intermediary medium to detect pinching conditions. Instead of direct mechanical contact between switching strips, the system uses light beams that are modulated by the pinching event, providing indirect but reliable detection at lower cost.
2Reliability
If safety devices are installed in the drive unit or drive gear motor, then pinching protection is provided, but retrofitting existing devices becomes impossible
Solution Approach 1:
The patent divides the safety system into separate, modular components (light transmitters, receivers, and control circuitry) that can be independently installed on existing furniture parts. This segmentation allows retrofitting without modifying the original drive unit or motor, enabling safety upgrades in already-operational devices.
Solution Approach 2:
The patent transitions the safety detection from the mechanical dimension (inside the drive unit) to the optical dimension (external light fields). This dimensional change allows the safety system to operate independently of the original mechanical structure, enabling retrofitting on existing devices.
3Reliability
If switching strips are used for safety detection, then pinching protection is achieved, but the system becomes disturbing
Solution Approach 1:
The patent replaces the mechanical switching strip system with an optical detection system, eliminating the mechanical contact and associated disturbances (noise, wear, interference) while maintaining the pinching protection 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
The optical safety system effectively detects slight deformations during pinching, enabling safe shutdown or reversal of the drive motor, while being inexpensive and easily integratable into existing electromotive adjustment devices, ensuring safety without the need for expensive components.
Implementation Method 1
a light transmitter (12) arranged in a housing (11) coupled with the furniture part (10) to be adjusted or with a further component (10) which is in connection with this furniture part, and a light receiver (13) arranged in the housing (11) or in a separate housing, wherein the light beam impinging on the furniture part or the further component in connection with this furniture part will be reflected and will meet the light receiver (13)
Data Source
AI summary
An electromotive adjustment device for a piece of furniture having an adjustable furniture part. The electromotive adjustment device includes a housing, a drive gear motor, a control device having a device housing, and at least one drive unit having an output member connected to the adjustable furniture part. The drive gear motor is configured to be one of brought to a standstill and reversed by a safety device during the occurrence of a pinching between one or more of two furniture parts, a furniture part and a component, and a furniture part and a part of a person's body. The safety device includes a light transmitter configured such that a light beam directed against one of the adjustable furniture part and the component and the light beam is reflected to meet a light receiver.