As any other passenger hub today, modern railway installations comprise a selection of audio-visual equipment to provide there various services. There are video systems for the control of the security in the terminal and the operation of the trains and rails. In publlic areas you find large numbers of digital information displays providing travelling information and advertisements to the passengers.
Both, control room operations and passenger information are demanded to be in service 24 hours per day on 365 days per year. This, combined with the difficult operating conditions in a passengerr terminal, requires a highly developed solution for the display of the relevant information.
Video Wall Systems in Control Rooms
Regarding the control room installations, we usually find numerous signal sources including video streams from CCTV cameras and static grids provided from rail management software and building management software. These numerous different signals are often displayed together on one large video wall providing a comprehensive overview to the operators in the control centre. For the technology of the video wall there are two different technologies which come into consideration. The leading technologies for larger control rooms is DLP rear-projection.
Here, a set of so-called rear-projection cubes is combined to an almost seamless video wall with a very high resolution. These cubes are available in a wide range of sizes and resolutions to fit any application. The major advantages of DLP cubes are there perfect ability to be operated in 24/7 mode. There is absolutely no danger of burn-in effects with static images and the cubes use components which are optimised for long-term operation.
Especially since there has been a change of the light source of the projector from lamps to LEDs which provide more than 50,000 hours life-time in continuous operation. The second technology used in control rooms is Liquid Chrystal Display (LCD). Here you have either a larger number of individual screens or a combined video wall comprising several modular LCD screens. The problem with individual screens is that their size and resolution are limited. LCD-based video walls are assembled of a matrix of "seamless" LCDs. The latest versions of these so-called narrow bezel LCDs allow a gap between the contents of two neighbouring screens in a video wall of less than 7 millimetres.
The problem with LCD is the danger of burn-in effects (e.g. image retention) when static image content is displayed for longer periods of time in the same position of the screen. This partly irreversible effect is caused by the composition of the different layers of the screen and is hard to prevent when static content has to be displayed. In control rooms this can be grids or not changing ares in video images. The main advantage of LCD technology is the price of a system compared to DLP cubes and their space saving installation possibility.
Whichever technology is used, it is important to rely on a professional provider. The lower costs for minor quality may be attractive for the initial purchase, but when it comes to reliability, service and operation these savings will not pay off.
Ideally the entire system should be delivered by a provider who offers a complete system including the display solution, the necessary graphics controllers for the connection of the various signals, a wallmanagement softeware solution and all peripherical devices which are necessary for a stable operation. In delicate environments such as control rooms it is absolutely necessary to have perfect compatibility of all devices and systems within the installation to guarantee the service of the transport system and the security of the passengers.
Display Technologies for Digital Signage
Video Screens in public areas have to fulfil different requirements compared with a "controlled" control room environment. There are changes in temperature and humidity, dust, vandalism, different viewing angles and interactivity, to name only some of them. Many different display technologies try to face these demands, but in the end the precise application in hand determines which is the best solution.
Most commonly used are LCD displays, either individual screens or video wall arrays of narrow bezel displays. Sometimes we see plasma displays which are perfect with moving video images but very likely to burn in when images or parts of images a re displayed statically for some time. New technologies like small rear projection iles and laser phosphor displays are still evolving, but will become an alternative to LCD, especially because of their possibility to be assembled without a viewable gap between the individual modules.
Little rear projection units and laser phosphor displays can be used to set up non-rectangular display arrangements which is especially interesting for advertisement purposes, and secondly their power consumption is decisively less than that of LCD or plamsa screens. So there is no finite answer to the question for an ideal display technology in public areas, there is a wide range of solutions available and everyone finds its application, just ask the expert. We have them all, eyevis - simply perfect visual solutions.