The expanding device (200) comprises a plate (20) connected internally to at least one panel of the display and divided by a first hinge into first and second plate portions (20a, 20b). An elastic tensile element (7) pulls the first and second plate portions (20a, 20b) to fold the plate (20) around the first hinge from a flat folded position to an angled working position. A limiting member (23) is hingedly connected to the first plate portion (20a) by a second hinge (22) and is provided with a free edge (23a) which, when the plate (20) is in an angled working position, is in contact with the second plate portion (20b) in order to limit the folding of the plate (20) to the angled working position. The second hinge (22) forms an angle greater than zero degrees with respect to the first hinge.
