The AMR sensor is equipped with an internal clock signal which constantly detects the magnetic flux judging whether to switch on. This clock frequency is referred as a response cycle. AMR sensor having high response cycle is recommended to be used to detect faster movements such as meter rotations, however the currenct consuption becomes larger. Conversely, the lower the response cycle, the lower the current consumption. Therefore, AMR sensor having low response cycle is recommended to be used for open-close detection.