Painting the town LED

One of Copenhagen’s key landmarks is the so-called “Light Screen” on the Politiken newspaper building in the Town Hall Square. An international alliance of companies has come together to bring it up to date with the latest LED Technology.

Large format display technology has come a long way since 1926 when the Politiken newspaper first installed a large screen on the side of its building in Copenhagen’s Radhusplatsen. Just above the square’s main bus stop, it is a valued source of information, and also a prime position for advertising to visitors to this 24-hour city.

The current installation is the fourth generation of board to grace the building, replacing a Daktronics board, which was fitted in 1991. Old age was being to take its toll on this and the number of failures was starting to make maintenance costs prohibitive.

Service of the old board was also extremely challenging logistically. All work had to be carried out from the front, requiring scaffolding and / or lifting gear for each piece of maintenance. One of the requirements of the new screen would be that maintenance would have to be made considerably easier.

Finally, the old screen was simply out of date. In the last 15 years huge advances have been made in LED screen resolution, energy efficiency and colour definition. It was time for a change.

Politiken’s construction office carried out its own research and eventually contacted Lighthouse Technologies after looking at several reference sites, particularly the Coca-Cola screen in London’s Piccadilly Circus.

The new screen supplied by Lighthouse has several features making it suited to its position. The basic unit is a variant on the P16 panel, the P16SA. The SA model features LEDs, which are actually angled down by 15º. This allows people who are relatively close to the screen, for instance at the bus stop, to see the content clearly. 16mm pitch was deemed a suitable resolution for the screen, and provides acceptable image quality from 95% of the square.

Directing the light like this also reduces the required intensity on the direct viewing angle. This leads to reduced power consumption overall, and extends the lifetime of the components, another cost reducer

Light intensity on the board is regulated by Lighthouse’s ABC – Automatic Brightness Control – technology. It can vary the intensity between 1% and 100% depending on the ambient lighting conditions.

Another key feature of the screen is its curvature and length. Whilst only two meters high, the board is 24 meters long and curves 90º around the side of the building. The shape had to be very close to its predecessor’s, to comply with Copenhagen’s planning laws. The curved section actually consists of a further variant of the P16 panel, the P16SAC.

Driving the LED screen is a pair of Lighthouse’s LIP-KX interface processors. Signals come from the controlling PC, and a custom VGA splitter divides it between the two LIP-KX units. Content ranges from news headlines, weather and sports results to advertising, which takes up around 25% of the screen time. All the diagnostic features of the screen can be accessed via the web, including temperature monitoring and analysis of potential fault conditions.

Two processors were needed to the extreme width of the screen. It runs at a resolution of 144 x 1540, with each processor taking a section of 144 x 770. Overall the screen is made up of 72 panels, and 630,000.

Fitting the board required the building of a multinational team. Churie Chang from Lighthouse Development and Jens Schelde of the recently established Lighthouse office in Denmark headed it up.

The installation was carried out by Danish integrators Dansk Data Display (3D), with the complex steelwork to mount the structure being designed and built by Belgian company Screen Design in partnership with engineers Birch & Krogboe.

Once the organisation was complete, the installation itself was carried out extremely quickly. Technicians from Screen Design and 3D took only two weeks to demolish the old screen, built the steel structure and install the new panels. A significant challenge in the project was the construction of an access gantry behind the screen, which was essential to improve maintenance access. Impressively, the first switch on of the screen resulted in an error free start up.

Politiken’s Marketing Manager Poul Skøtt is delighted with the results: “The Politiken screen has been a key part of our identity for most of the 20th century and we’re really pleased that we’ve now brought it into the 21st. The new board will use only 20% of energy of the old one, and in addition there will be significantly reduced maintenance costs thanks to the rear access solution.”

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