Patent ID: 7466482

Claim:
A display unit comprising: a housing having a front end portion that defines a front opening, upper and lower walls, and two opposite side walls interconnecting said upper and lower walls, said housing being formed with a first rib that protrudes from one of said upper and lower walls and that extends between said side walls in a transverse direction relative to said side walls, and a first retaining groove that is indented from the other of said upper and lower walls, that extends between said side walls in the transverse direction, that is aligned with said first rib in a normal direction relative to said upper and lower walls, and that has a size corresponding to that of said first rib so that when said housings of two of said display units are stacked one above the other, said first rib on one of said display units is fitted into said first retaining groove in the other of said display units; a screen mounted on said front end portion of said housing for covering said front opening; and an image projecting device mounted in said housing for projecting images onto said screen.