CONTACTLESS SENSING INPUT DEVICE

摘要

A user input apparatus and method for providing control for an electronic device uses contactless sensing. The user input device includes a substantially circular disk having at least one ferromagnetic plate located adjacent to a periphery of the disk and coupled to the disk. The input device also includes a magnet and a magnetic sensor adjacent to the magnet and with magnetic sensor's sensitivity axis oriented parallel to the magnet. The magnet and the magnetic sensor are situated near the periphery of the disk on a circuit board such that, as the disk is rotated, the ferromagnetic plates coupled to the disk pass within a predetermined distance from the magnet but do not contact the magnet or the magnetic sensor. The magnetic sensor outputs a signal when the at least one ferromagnetic plate passes within the predetermined distance from the magnet. The input device is also configured to enable a user to detect a rotational resistance of the disk when the ferromagnetic plate passes within the predetermined distance from the magnet, thereby providing a tactile feedback to the user of the input device.