A display apparatus includes a display that displays individual images in a plurality of viewing directions on a common screen, a main body having a different chassis from that of the display, a display fan that cools down inside of the display, and a main body fan that cools down the inside of the main body. The method for operating the memory cell includes establishing a high threshold state in the memory cell by injecting negative charge into the charge trapping structure to set a high state threshold. Also, the user may adjust the amount of rotation by the respective hinges so that the earphones rotate to the user-defined limit position. The device may also include a locking insert to which the locking element may be threadedly engaged in order to further ensure that the device is locked.