TECHNOLOGY

Dysten is a Polish technology company. Our work requires continuous improvement, commitment of a large team of engineers and passion to turn high-tech dreams into efficient, reliable devices that improve the comfort of passengers, inhabitants, users.  We know and use all important technologies, manufacturing high class devices. This is confirmed by successful implementations, 20 years of experience, international awards and a constantly growing number of orders.

While reading the information below, please remember that it does not replace contact with our Project Manager, who takes into account all aspects of the project and will suggest the best solution. Seemingly trivial details generate long-term consequences.

Raster and colour in LED displays

The decision to choose the parameters of LED displays for passenger information systems most often results from their superiority over LCD technology – thanks to higher brightness, durability and energy savings.  However, the choice of LED technology is only the first of several important decisions.  The next one concerns the image colour scheme – the device can have a single-colour display or display the full range of RGB colours.  The correct raster size is equally important.

Pixel and raster

What is a raster in LED displays?  It is the distance between the nearest pixels (points of the displayed image) specified in millimeters.  A pixel on a monochrome screen is a single diode that can shine at different brightness, but only in one colour, such as amber.  In RGB LED screens, a pixel is a single SMD diode that can change the color of light.

Dysten most often uses raster is 3, 4, 6 mm.  What is the risk of a miscalculated raster? The words and numbers on the display will be blurred for passengers and in extreme cases illegible.

The most important readability

Knowing the destination of the device and the dimensions of the station hall or waiting room, we know the range of distances at which travellers can read information.  Multiplying the size of a raster (pixel pitch) by 1000 allows to estimate the minimum distance.

For example, a screen with a grid of 4 millimetres will be readable at a minimum distance of 4 meters.  A smaller distance will make the diodes become a group of points for our eyesight and it will take effort to put them into words or numbers.

Distance and legibility

It is most often assumed that the character displayed – a number or a letter – will be sufficiently well visible from a distance if its minimum size is 1/2000 of the viewer’s distance.

Free of charge support

Since there are many parameters to be taken into account when developing the assumptions, we invite you to contact us by e-mail at [email protected].

We [email protected] help you to choose the right parameters for your devices.

Selection of display technology

It has been long since passenger information displayed only information about arrivals and departures. Intelligent passenger information systems calculate the arrival time and delays as well as display special messages and warnings. However passengers will make use of this information only if the displayed content is visible from the place where they are and at the moment when they need it. Which means that a suitable display technology must be selected from the many options available.

The following table helps in a preliminary selection of technology which is the most suitable for your needs and applications, depending on whether you need a device for a large bus station or a small timetable for a distant tram stop with no power connection.

Backlit LCD displays

Features

The whole LCD matrix is backlit – white letters and digits against a blue background. Other colour combinations are available however in the railway transport the combination of blue background and white characters has turned out to be the most effective. The devices can be waterproof (IP65), while the casing can be painted in any RAL colour and be vandal-resistant. They can be operated 24/7, indoors and outdoors. The signal is transmitted digitally through DVI/HDMI/LAN/serial connections.

Applications

Large and small monochromatic (one-colour) passenger information displays in small, middle-sized and large station halls, displays on platforms. The devices may be equipped with a clock.

Advantages

Good visibility and wide viewing angle. High contrast, text sharpness, attractive price.

Disadvantages

Backlit LCD displays consume more energy as a result of lighting the whole matrix.
Efficient operation in heavy frost or heat requires enhanced systems of balancing temperature.
Low mechanical resistance of the matrix – it must be particularly protected.
Proness to electromagnetic (radiation and other devices, magnets, strong magnetic fields, loudspeakers) and electric (e.g. power supply units, transformers) disturbances.

TFT LCD displays

Features

A thin-film-transistor liquid-crystal display (TFT LCD) is a fast matrix in which 4 transistors, responsible for each one of the three colours (red, green and blue) and brightness, are assigned to each pixel. Edge lighting with white LEDs.
The devices can be waterproof (IP65), while the casing can be painted in any RAL colour, be vandal-resistant and be also equipped with built-in surveillance camera. They can be operated 24/7, indoors and outdoors. The signal is transmitted digitally through DVI/HDMI/LAN/serial connections.

Applications

In locations where passengers read and view the content from a small distance – even the most complicated graphics in full colour and high resolution, animations, films, commercials, maps, connection plans, articles, warnings, explanations. Typical devices: infokiosks, information totems, platform boards, displays in tunnels, underground, inside trains. The devices may be equipped with a clock. The change of content can be done with buttons or is managed remotely.

Advantages

High resolution, e.g. Full HD, sharpness and more detail of image and text. Full palette of displayed colours and their grades. Very quick matrix response (fast change of content with no smudges).

Disadvantages

TFT LCD displays are prone to mechanical damage – they require a special protection of the screen. The device requires additional systems of balancing the inner temperature in very high and low ambient temperatures. Without an additional protection it is not resistant to electric and electromagnetic disturbances. The maximal size of manufactured matrices limits the size of the screen. Matrices can be combined into a large video wall, however several-centimetre frames are visible.

Monochromatic LED displays

Features

Every pixel is a monochromatic LED. Visible raster is a particular feature of monochromatic LED displays. The most common are displays with amber LEDs. 3, 4, 6 and 8 mm rasters are the most frequent. It is possible to regulate the brightness of LEDs depending on the ambient luminosity. The devices can be waterproof (IP65), while the casing can be painted in any RAL colour, be vandal-resistant and be also equipped with built-in surveillance camera. They can be operated 24/7, indoors and outdoors. The signal is transmitted digitally through DVI/HDMI/LAN/serial connections.

Applications

Large passenger information displays, platform boards, boards on the sides of railway wagons. Marking of stops and platforms, with the option of dynamic change of content.

Advantages

Possibility to manufacture a board of any size. High brightess and contrast, visibility even in bright sun (it is possible to reduce brightness at night). Long lifespan. Wide viewing angles, up to 170 degrees. Mechanical resistance. Digital signal DVI/HDMI enables using any fonts. Stable lighting parameters. Exceptional durability, much greater than of other LCD solutions.
The failure of a single LED does not switch off the whole screen. It can be manufactured in any size. High resistance to weather conditions – low and high temperatures. High resistance to electromagnetic disturbances – the proximity of loudspeakers, telephones, strong magnets, multiple units, locomotives.

Disadvantages

Monochromatic content. They are not suitable for reading from a short distance (e.g. 1 m). It is not possible to display full-colour content. The screens and the size of the display are usually bigger than of LCD displays: the same content on an LCD display of higher resolution occupies multiple less space.

Full-colour RGB LED displays

Features

Every pixel is an SMD LED, which can be any colour depending on the needs. It is possible to regulate the colour of a single pixel and the brightness of the LED. RGB LED is
the development of the monochromatic LED technology. A full colour palette and any content can be displayed. The devices can be waterproof (IP65), while the casing can be painted in any RAL colour, be vandal-resistant and be also equipped with built-in surveillance camera. They can be operated 24/7, indoors and outdoors. The signal is transmitted digitally through DVI/HDMI/LAN/serial connections.

Applications

Large and small passenger information displays presenting arrivals and departures, delays and other content. Wall screens in station halls, Displays inside and outside vehicles (railway wagons, buses, trams). Marking of stops and platforms, with the option of dynamic change of content.

Advantages

It is possible to manufacture a board of any size. Very high brightness, contrast and visibility, even in full sun (it is possible to reduce brightness at night). Wide viewing angles, up to 170 degrees. Long lifespan. Energy-efficiency. Digital signal enables using any fonts and display any content in full colour (16.7 mln colours), e.g. animations, commercials, films. High resistance to electromagnetic disturbances. Cost similar to that of monochromatic LED displays.

Disadvantages

They are not suitable for reading from a short distance.

E-paper devices

Features

These are devices of extremely low energy consumption, which supports the concept of smart city and the remote change of content. They enable displaying graphics and text depending on version: in grey scale, in limited colour palette and in 16 grey levels.
The screen of the device can have the diagonal size of 13, 31, or 42 inches or their multiple. It is possible to combine screen to obtain a larger display.
This technology uses capsules immersed in a liquid of high density over a mat which changes the potential locally. As a result the dipole (+/-) capsules are turned by 180 degrees and as a result their white or black part is visible, which corresponds to a single pixel of the screen. E-paper can be lit in the same way as an ordinary sheet of paper.
The devices can be waterproof (IP65), while the casing can be painted in any RAL colour, be vandal-resistant and be also equipped with a built-in surveillance camera. They can be operated 24/7, indoors and outdoors.

Applications

Passenger information, also dynamic, of any content, with text and graphics, e.g. timetables, maps, extended descriptions and articles with text and graphics. Marking of points of sale, menus, direction boards, price tags, advertisements, any variable content information. Ideal low-cost solution, for underground and stops, managed remotly.

Advantages

Very high comfort of reading. Good visibility even under bright illumination. E-paper devices are usually very light and do not require a supporting structure – they can be mounted on walls, posts, drywalls, even doors. E-paper does not consume energy at all, except for a moment when content is changed. It is possible to use a battery or a solar panel as a source of energy. Power connection is not required. The devices can display dynamic passenger information.

Disadvantages

Basic versions of an e-paper device display black-and-white content, in grey scale.
E-paper is not suitable for displaying video and animations.
It requires additional lighting under dark conditions.
In extremely low temperatures it is necessary to warm up the display before the change of content.

Low power devices

Features

Monochromatic transflective displays of small size and very low power consumption. They switch on a backlight under dim and dark ambient situations when there is too few reflected light to read the content. Their casing size is 78 do 110 centimetres and they are intended for mounting close to a passenger. The devices can be waterproof (IP65), while the casing can be painted in any RAL colour and be vandal-resistant. They can be operated 24/7, indoors and outdoors.

Applications

Ticket offices, stands, passenger information on stops, tourist information, variable content direction boards.

Advantages

Light device of extremely low power consumption. Variable content is displayed with integrated managing system. The devices can display graphics and are equipped with a built-in backlight, which is turned on when the reflected ambient light is not bright enough.

Disadvantages

Limited colour range of displaying content. Displaying films, animations and video is not possible. Limited resolution.

However, if you have any questions, we will be happy to help you. Send the assumptions of your concepts to [email protected] and we will consult them for free. You can also use this form.