Reed sensors in Central Locking of Cars with Remote Keys
Central locking allows the driver or front passenger to simultaneously lock or unlock all the doors of an automobile. This is achieved by a secure coded radio frequency signal sent from an electronic key which has already been paired with the microprocessor. The key code is compared with on-board computer which then sends a signal to the central locking system. Although these doors are mostly controlled by the remote key, for manual opening of the doors, reed sensors are used. The sensors are mounted on the doors, and magnets are mounted beneath the door handles. If the handle is lifted, the reed sensor detects this and sends a signal to the computer to open the doors. An added advantage is that the same reed sensors can be used as security devices to trigger alarms when the door is opened in an unlocked condition.