Capacitive Proximity Sensor for Low Power Vehicle Access
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Solution Overview
Problem
Motor vehicles with contactless access authorization systems face high power consumption due to constant operation of detection devices, especially when parked in crowded areas, leading to rapid battery discharge and reduced user convenience.
Innovation Solution
A capacitive proximity sensor system that switches on only when the user's body part is detected, with adjustable detection area and automatic shutdown when not in use, combined with a control device that manages power consumption by switching off unnecessary components, including the detection device when the access authorization means is removed or not present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the detection device operates constantly to enable contactless opening of vehicle parts, then user convenience is improved, but power consumption increases rapidly
Solution Approach 1:
The detection device operates periodically instead of continuously. A proximity sensor first detects the user's approach, then triggers the detection device to activate only when needed. This periodic operation mode maintains contactless opening capability while dramatically reducing overall power consumption during parked periods.
Solution Approach 2:
The proximity sensor performs preliminary detection of the user's approach before activating the power-intensive detection device. This preliminary action allows the system to prepare for potential contactless opening operations only when a user is nearby, avoiding unnecessary activation and power consumption when no user is present.
2Adaptability or versatility
If the detection device is activated frequently in crowded areas, then access authorization can be verified for multiple users, but average power consumption increases
Solution Approach 1:
The system uses periodic activation triggered by proximity detection. In crowded areas, the proximity sensor identifies when someone approaches, then activates the detection device only at those moments. This maintains multi-user access capability while reducing average power consumption compared to continuous operation.
3Area of stationary object
If the detection area is enlarged to improve detection range, then user presence can be detected from farther away, but power consumption and interference increase
Solution Approach 1:
The detection system is segmented into two stages: a first proximity sensor with a first detection area for initial user approach detection, and a second detection device with a second, smaller detection area for detailed access authorization verification. This segmentation allows the system to use the larger detection area only when needed for initial detection, reducing overall power consumption and interference.
Solution Approach 2:
The detection area dynamically adjusts based on operational needs. The proximity sensor provides a larger initial detection area for approach detection, then the system transitions to the detection device with a smaller, more focused detection area for verification. This dynamic adjustment optimizes both detection capability and power consumption.
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
Significantly reduces power consumption by limiting operation to only when the user is present and adjusting detection area dynamically, ensuring low power usage and interference-free contactless detection while preventing accidental vehicle part opening/closing.
Implementation Method 1
the capacitive proximity sensor advantageously enables very low power consumption compared to a corresponding optical proximity sensor or a proximity sensor that works with ultrasound or radar radiation
Data Source
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AI summary
The motor vehicle (1) has vehicle pieces (2,3), particularly a rear flap or a vehicle door, where the vehicle pieces are adjustable in an opening and closing position. An actuation unit is provided for automatic adjusting the vehicle pieces between opening and closing position. A proximity sensor is provided for detecting a body part (22). A control unit stands with a switching unit in a control connection such that a detection unit (6) is actuated, if the proximity sensor detects the presence of the body part in the part of an external area (21). USE : Motor vehicle. ADVANTAGE : The motor vehicle has vehicle pieces, particularly a rear flap or a vehicle door, where the vehicle pieces are adjustable in an opening and closing position, and the actuation unit is provided for automatic adjusting of the vehicle pieces between opening and closing position, and thus ensures to provide a small current consumption of the actuating unit of the motor vehicle. DESCRIPTION OF DRAWINGS : The drawing shows a schematic perspective view of a motor vehicle. 1 : Motor vehicle 2,3 : Vehicle pieces 6 : Detection unit 21 : External area 22 : Body part.