A GROWING range of information display screen technologies is now available, each offering its own advantages and disadvantages in particular situations.

Light emitting diodes account for the majority of the displays supplied by Infotech, as they offer high reliability, long life expectancy, low maintenance, excellent legibility and low cost of ownership. Infotec produces a selection of standardised LED display modules, as well as large, custom-designed screens for station concourses. Densitron Ferrograph also offers a concourse display, with high-intensity LEDs, a micromesh sun-screen and 50mm characters designed to be seen up to 30m away. Each line of text is individually controlled, and the anti-glare screen can be hinged aside during maintenance.

Liquid crystal displays are widely used on European railways, in particular for platform clocks. LCDs share many of the benefits of LEDs, offering the luminance needed to be read in areas with sunny environments, but they can have higher maintenance costs owing to the need to replace the backlighting from time to time.

At the end of June, Dicoll Ltd was due to release a range of high-brightness and transflective sunlight-readable flat-panel LCD screens in four sizes up to 17 inch.

This month Vossloh Information Technologies will complete a contract to supply 20 LCD platform displays and 16 arrival and departure boards for eight OSE stations in Athens. Vossloh is also supplying control software to generate automatic voice announcements. This will initially run on standard PCs, later being networked within a wider control system to be managed by fewer staff.

The OSE order includes seven 40 inch TFT displays, using technology similar to that found on laptop computers. TFT screens are most suitable for indoor environments such as waiting rooms and ticket offices, where viewing distances are short and ambient lighting can be very bright. However, the technology is getting cheaper, and larger screens are increasingly being used outdoors.

Bailey Concepts has introduced the 20inch BrightEye TFT, which meets safety requirements for use underground. The 1600 x 1200 pixel screen has 16·7 million colours, and is designed for use with passenger information systems as well as in CCTV applications. A 30 inch screen is produced by Densitron Ferrograph, semi-ruggedised for use in ticket halls. It is available with an integrated computer as a master controller for an information system, or as an externally-driven slave unit.

The TFT panels available from Review Display Systems have anti-reflective coatings to cut down reflections from bright sunlight. A typical TFT screen’s antiglare white-filter surface will diffuse sunlight across the display, making it difficult to read, but the RDS coating prevents surface diffusion.

Housed in water and vandal-proof casings, cathode ray tubes use proven television technology to display information in outdoor areas including car parks and platforms. Although cost-effective, the monitors are cumbersome for indoor use.

Plasma screen technology has been one of the most popular choices in recent years, and Densitron Ferrograph has supplied 61 inch fully-sealed screens to London Underground. A 700W heat exchanger was designed for underground use, and the company plans to offer this with many of its future products.

Plasma screens can display a wide variety of information together with graphical content, but according to Infotech the total cost of ownership has sometimes been high. Whereas LED and LCD offer life expectancies in excess of 10 years, some plasma screens have failed after only three, because of fading and loss of contrast. Infotech is currently replacing over 100 plasma screens with LED-based equipment.

Rear projection displays are used for large scale high quality video images, and Densitron Ferrograph offers these in 67, 72, 84 and 100 inch models with Fresnel screen and LCD or DMD projector technologies for use on station concourses. A remote handset allows images to be adjusted to give the best appearance, and positive air pressure protects the internal mirrors from dust.

Station operators are seeking new opportunities to attract advertising revenue, including showing video images adjacent to departure information. Screen Technology has developed ITrans to magnify an LCD image for projection on a large screen. A prototype 68 inch screen has a seamless image produced from 16 individual tiles, and work is in hand to demonstrate the system up to 200 inches, filling a gap in scale between smaller plasma screens and larger LED displays.

CAPTION: Infotec supplied information screens for the refurbishment of Network Rail’s Manchester Piccadilly station

CAPTION: Visi-Shade light-deflecting lenses from Admirals Quay Ltd have been fitted to screens at London Waterloo to improve readability in bright sunlight. The bespoke shades divert incoming ambient light away from the screen while letting emitted light pass through

TABLE: Reader Enquiry Numbers:

Admirals Quay 121

Bailey Concepts 122

Densitron Ferrograph 123

Dicoll Ltd 124

Infotech 125

Review Display Systems 126

Screen Technology 127

Vossloh IT 128

Passenger Information in Brief

India’s Southern Railway is testing a GPS-based passenger information system on the Kovai Express. A screen displays the location of the train at any time in its journey, along with information on the next station and expected arrival time. Logs are produced which make it easy to track progress and identify delays.

In the first three months of this year the Association of Train Operating Company’s www.nationalrail.co.uk received 10 million visits, five times higher than the same period last year. The journey planner for Great Britain now accounts for 47% of National Rail enquiries, up from 13%.

On May 28 Russian Railways President Gennady Fadeev opened a 300m rouble new station building at Labytnangi on the Northern Railway. The station has a state of the art public address system throughout the building, as well as CCTV monitoring and four ticket windows with an electronic queuing system.

Transport for London’s on-line journey planner is now accessible free of charge from 500 internet-equipped public telephone kiosks. Pre-programmed with their location, the kiosks can advise users how to reach a specified address, postcode or place of interest by public transport.