Digital electronic signs

The term digital sign means that an information system about departures of public transportation vehicles has been embedded in a stop sign or that an independent panel is a part of a stop sign. Embedded LED panels for stop signs are characterized by a low number of lines (1 – 4) and a high density LED spacing (4 – 5 mm). In the LCD solution a substitution of a simple schedule is expected (more lines). The reading distance of digital signs is usually shorter – up to 15m maximum corresponding with the font size of 3 cm.

In the case of  a central dispatching collecting vehicle position information, LED (LCD) signs can display up to date departures according to the position of a vehicle on the line.

They are produced in two versions:

Digital signs of the LED type

Embeddable LED panels for stop signs are characterized by a low number of lines 1-4 and a high density LED spacing – 4-5 mm. The reading distance of digital signs is usually shorter – up to 15m maximum corresponding with the font size of 3 cm. They are produced in two versions:

• simulating large stop panels, i.e. they display the line, the target stop and the time of departure,
• Displaying only the time of departure under the line and this information alternates with information from the dispatching.

Both versions make passenger orientation on stops much simpler. If a seamless active LED surface is used it is possible to display any graphic features. More information about digital LED signs here.

Digital signs of the LCD type

A version with an LCD display is another possibility. Our customers can choose either the TFT type (a standard rendering with a 10,4″ or larger color high illumination display)  – see e.g. our solution at Svinovské mosty, Ostrava, or a solution with small independent numeric LCD indicators for each line (used by some DPs [1] in Bohemia). If TFT high illumination LCDs are used our comparison of  LCD and LED systems is applicable, however, it is to be taken into account that embeddable displays can be screened off somehow which means that their consumption will not be so different (but the lifespan problem remains).

However, it applies generally that this type of digital signs contains “relatively” small letters making them readable from short distances. The assumption is that a passenger stands at the sign and reads it instead of reading a paper schedule. More information about LCD signs here.

A capacity touchscreen can be added to these panels enabling them to function as information stands – see. I-points based on our solution.

Power supply of digital signs

Providing power supply to digital signs can pose a problem for it is necessary to build it which is usually more expensive than the whole sign. The following can be used as a source of power:

• standard 230V distribution systems,
• power supply from a tractive distribution system,
• power supply from public lighting when a sign needs daytime accumulators,
• power supply from alternative sources.

If there is no 230V distribution system, power supply using tractive voltage can be arranged. Using solar panels is not recommended based on measurements we made in January 2010 when there were only three sunny days a month and the solar panels would have to be up to 10 m2 large.