A mobile videophone terminal capable of transmitting display information obtained through data communication and the like to a receiving end while talking on the videophone to display it at both ends in real time. The system includes an electronic shelf label system including an ESL, a radio frequency identification label interrogator associated with the ESL, RFID labels attached to items associated with the ESL, and a computer. The density of the plasma in the region of the magnet assembly of the magnetron is intensified for a fixed target power by reducing the size of the magnets.