Abstract: A data delivery system has a capability of effectively and reliably protecting copyright of the data. A video source of a movie or the like is delivered in the form of encrypted data from a server apparatus to a playback apparatus. A decryption key used to decrypt the encrypted data is stored on a storage medium such as a memory card, and the storage medium is sent from the server apparatus to the playback apparatus in parallel with the delivery of the encrypted data. After completion of the playing of the movie by the playback apparatus in a movie theater, the storage medium is returned to the server apparatus. The server apparatus examines information stored on the storage medium to check whether the video source delivered in the form of data has been properly used in an authorized manner.

Abstract: A data delivery system has a capability of effectively and reliably protecting copyright of the data. A video source of a movie or the like is delivered in the form of encrypted data from a server apparatus to a playback apparatus. A decryption key used to decrypt the encrypted data is stored on a storage medium such as a memory card, and the storage medium is sent from the server apparatus to the playback apparatus in parallel with the delivery of the encrypted data. After completion of the playing of the movie by the playback apparatus in a movie theater, the storage medium is returned to the server apparatus. The server apparatus examines information stored on the storage medium to check whether the video source delivered in the form of data has been properly used in an authorized manner.

Abstract: A screen cover opening device for a television receiver is provided with a screen cover openably closing left and right side portions or upper and lower side portions of a screen adapted for electively displaying plural different aspect ratio images. Two vertically extending rolls 5a, 5b are arranged at outwardly shifted positions from left and right lateral sideswrapped around of the screen 2 and an endless cover sheet 3 is wrapped around these rolls. Two windows 4a, 4b are formed at longitudinally spaced apart positions of the cover sheet 3. The rolls are rotated to run the cover sheet to change overlap of the two windows to change the transverse width W that may be viewed through overlapped portions of the two windows.