Solari departure board

A split-flap display, or sometimes simply flap display, is an electromechanical display device that presents changeable alphanumeric text, and occasionally fixed graphics.

Often used as a public transport timetable in airports or railway stations, as such they are often called Solari boards after display manufacturer Solari di Udine, of Udine, Italy, or in Central European countries they are called Pragotron after the Czech manufacturer.

Split-flap displays were once commonly used at consumer scale in devices known as flip clocks.

Each character position or graphic position has a collection of flaps on which the characters or graphics are painted or silkscreened. These flaps are precisely rotated to show the desired character or graphic. These displays are often found in railway stations and airports, where they serve as flight information display system and typically display departure or arrival information, although digital equivalents are far more common now.

Sometimes the flaps are large and display whole words, and in other installations there are several smaller flaps, each displaying a single character. The former method is limited to the words it can display on the flaps, while the latter system is not, and output messages can be changed without the need for the addition or replacement of flaps, although images cannot. In the example image on the right, the destinations in the centre of the picture are split into characters, while the messages left and right of these occupy one flap each.

During a power loss or disruption the display will freeze. At first this may be an advantage because the information is still correct. When the information becomes outdated it might be worse than no information.

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