A method for detecting the invalid access to a computer network is disclosed. The method further includes storing a preceding field that immediately precedes the current field in the digital video signal, and storing a succeeding field that immediately succeeds the current field in the digital video signal. The main body has a through hole for face down sleep, a matching element for fitting with the through hole, and a circuit board inside the main body for connecting to a vibration unit and a rotation unit. Thus, when changing the channel, for example, it is possible to quickly obtain output picture data, shorten interruption of the pictures, and check a picture of the next channel in a short time.