A magnetic recording medium includes a servo area where servo data used for detecting a position of a magnetic head on a magnetic recording medium is recorded; and a writable data area, arranged side by side with the servo area in a track direction, on which user data is written by the magnetic head. A third passivation film 45 is disposed under the EL element 203 comprising a pixel electrode 46, an EL layer 47 and a cathode 48, and diffusion of alkali metals from the EL element 203 formed by ink jet method into TFTs is prevented. The method utilizes optical emission to monitor fluorescent light emission from the emitters for determining system component status.