A split-flap display, sometimes simply flap display, is a display device that presents alphanumeric text, and possibly fixed graphics, often used as a public transport timetable in some airports or railway stations, often called Solari boards, named after display manufacturer Solari di Udine from Udine, Italy.
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 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 When the information becomes outdated it might be worse than no information.
Flip-dot displays and LED display boards may be used instead of split-flap displays in most applications. Their output can be varied more easily (by reprogramming instead of replacement of physical parts in the case of graphics) but they suffer from lower readability. They also can refresh more quickly, as a split-flap display often must cycle through many states.
Many game shows of the 1970s used this type of display for the contestant podium scoreboards. Usually, the flip was left-to-right on a vertical axis, although up/down on a horizontal axis was not completely unknown. In Italy, split-flap displays have also been occasionally used as destination signs for transit vehicles, there was also a brief vogue for them in the uk in the mid 1980s.
Advantages to these displays include:
- high visibility and wide viewing angle in most lighting conditions
- little or no power consumption while the display remains static
- Distinct metallic flapping sound draws attention when the information is updated.
In the case of the latter the Massachusetts Bay Transportation Authority has specifically designed the new LED replacements for its aging Solari boards at North Station and South Station to emit an electronically generated flapping noise to cue passengers to train boarding updates.
Pop culture references 
- In the game Call of Duty: Modern Warfare 2, during the level "No Russian", a split-flap display can be seen and heard transitioning all flight details to "DELAYED" after a terrorist attack on the airport.
- The game board on the Nickelodeon game show Make the Grade was a 7x7 split-flap display, used to display subjects and wild cards, as well as tracking contestants' progress.
- The television game show Chain Reaction on GSN features computer-simulated split-flap displays to display the various words in a chain.
- The 1993 movie Groundhog Day prominently featured an alarm clock-radio with such a display. The transition from 5.59 to 6.00 was the trigger mechanism for the time loop being experienced by Phil Connors.
- The 2004 movie The Terminal shows such a display being used in the airport where the main character Victor Navorski is trapped.
- The television show Lost prominently featured a split-flap counter during its second season.
- The cover of The Enemy's debut album We'll Live and Die in These Towns featured a split-flap display.
Operational boards in transport terminals 
The boards are currently in use at the following stations:
- Melbourne Airport (Melbourne Tullamarine Airport, IATA Code MEL). Located in T2 (international terminal).
- Paris Gare du Nord departures
- Frankfurt Airport (Flughafen Frankfurt am Main, IATA Code FRA) has Solari boards throughout the airport, still in use as of March 2012[update]. Each row ends with a pair of green and red lights which flash to indicate that flight is boarding. They indicate each flight's destination, its flight number and carrier, and its departure gate and time. This particular board is known for mixing up, and creating new airport names.
- Kolkata Airport. Boards near domestic and international departure entrance.
- Chennai Airport - Boards both inside and outside the terminals.
- Roma Termini. Boards located after the ticketing area above the track entrances. In addition, most Trenitalia stations have split-flap display boards.
- Milan Malpensa Airport. Board located in the check in area.
- Ninoy Aquino International Airport (Manila International Airport). Terminal's biggest timetable. In Terminal 1 Departures level. Over check-in desks and lobby.
- Otopeni Airport (Bucharest Henri Coandă International Airport) has Solari boards in the international departure area, including a pair of red lights on each row which flash to indicate an important message such as "now boarding".
- Belgrade Airport (Belgrade Nikola Tesla Airport, IATA Code BEG) has Solari boards on both levels of the departure area, still in use as of October 2011. Each row ends with a pair of red lights which flash to indicate that the flight is boarding or there is some other change in status. They indicate which destination a flight is to, its flight number and carrier, and its departure gate and time.
Sri Lanka 
- Bandaranaike International Airport (Bandaranaike International Airport, also known as Katunayake International Airport and Colombo International Airport, IATA Code CMB). Terminal 1.
United States 
- Atlantic City Rail Terminal. Located in waiting area.
- Jacksonville International Airport in Florida. It is on the second floor, in between the two check-in desks.
- Newark Penn Station. In waiting area located above entrance to track concourse.
- New Haven Union Station. Above stairway to platform concourse. Combined Metro-North and Amtrak. These will soon be replaced by two LED boards as part of an improvement project at Union Station.
- Philadelphia’s 30th Street Station. Mounted above centrally located information desk. Small flip boards located at the head of each track stairway.
- Providence Station. Located in waiting area
- Route 128 Amtrak Station in Westwood, Massachusetts. Located in waiting area.
- San Francisco Ferry Building. Located in the Great Nave, and a new installation (2013) rather than a “hold-out” from the pre-digital era.
- Secaucus Junction in Secaucus, New Jersey. In the Upper Level Concourse.
- Trenton Rail Station. Two side-by-side low profile boards in over-track concourse. Served by all trains except River Line Light Rail.
Boards no longer in operation 
Stations previously equipped with these boards included, amongst others:
United Kingdom 
- London Charing Cross, split into two sections with promotional images on destination blinds and up to two calling points per blind, operator shown below calling points, however as of 18 July 2007 these have now been dismantled and taken away replaced by the new LED boards like those used at Waterloo and Victoria.
- London Liverpool Street, taken out of service September 2007. A live webcam used to broadcast frequently updated images of this board, but is now replaced by a cessation announcement: . The board, pictured, was blue coloured, with one destination per blind, operator above calling points, and could show a range of special messages, including "Boat Train", "Special Service", "International", "Stansted Express" and "This train has been replaced by a substitute road service".
- London Victoria, replaced November 2004
- London King's Cross, replaced in the early 2000s
- Edinburgh Waverley, replaced by an LED departure board
- Glasgow Queen Street
- Birmingham New Street, replaced by LCD screens. The large clock from the board survives above the gateline, with the remaining panels replaced by advertising.
- Reading railway station
- London Waterloo, replaced by LCD units in the early 2000s, still there out of use until December 2006, when it was taken down to make way for an LED departure board that became operational in March 2007.
- London Paddington,was situated across the platforms and used to carry advertisements on the back, facing arriving passengers.
- Watford Junction, black coloured, full flip columns for Silverlink County services to Northampton, Southern services to Gatwick Airport, and Virgin Trains and First ScotRail services to North Wales, the North-West and Midlands of England and various destinations in Scotland. However, for Silverlink Metro services to London Euston and Silverlink County services to St Albans Abbey the calling points are fixed and only the time of the next train is changeable, due to all trains calling at the same stations.
United States 
- New York City's Grand Central Terminal, replaced by LCD units made by Solari di Udine during reconstruction of the terminal. It was one of the most famous of the Solari departure boards in the world.
- New York City's Penn Station also featured these boards in both the Amtrak portion and the Long Island Rail Road (LIRR) portion. The board in the Amtrak portion, which showed departure information, was replaced in 2000 by an LCD board. The boards in the LIRR portion featured departing trains as well as boards at the head of each stairway to platforms for tracks 13 through 21, which displayed the stops and connections associated with the posted train. These were replaced over a period of several weeks between February and April 2006. The new signs, also made by Solari di Udine, use a combination of LCD and LED technology.
- New York's Museum of Modern Art has a Solari flap display board in its permanent collection, on display in the design wing. The board itself works, and displays the original flight departure data for museum visitors (though reset to EST). The board was originally used in Milan's Malpensa Airport.
- New Carrollton Amtrak Station. (Removed in January 2010.)
- Baltimore Penn Station. (replaced by LED board January 2010)
See also 
- Flip clock
- Display device
- Pedestrian Drama, contemporary artwork using this display technology
- Juan Fontanive, a contemporary artist who uses the mechanism extensively in his practice since 2005.
- U.S. Patent 3,501,761 Remote-Controlled Display Device for Selectively Displaying Signs or Words
- "Eastern National Olympian Coach".
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