PURPOSE: To make a display screen easy to see by increasing the contrast of the display screen and eliminates the reflection of a background.

CONSTITUTION: A cathode 13 and a tapered cylinder 14 whose plane shape is circular are incorporated in an enclosure 12 wherein a discharge space is formed. The inside of the tapered cylinder 14 is partitioned by a partition plate 15 into four small light emission chambers 16a-16d which emit light in, for example, B, G, R, and G to constitute at least one picture element. A convex circular lens 21 is provided outside on the external surface of a rectangular display plate 20 which projects the respective emitted light beams out of the small light emission chambers 16a-16d. Anodes 18a-18d are arranged at the respective corner parts of the enclosure 12 outside the outer peripheral surface of this circular lens 21.