LEDs in Windows – What Purpose do they serve?

Adrian J Cotterill, Editor-in-Chief

HSBC Premier - Mayfair

I am not sure why a good brand like HSBC and especially its upmarket brand – HSBC Premier here shown in Mayfair would put an unreadable LED in its window and even worse, then proceed to scroll text across it.

Discrete inorganic light-emitting diode (LED) screens are an interesting topic when it comes to digital signage.

LED screen makers such as Daktronics and Barco have developed new 3mm pitch screens that can be used in some of the same applications as LCD and PDP.

LED has the advantage of long lifetimes and high reliability – although they are expensive and it is clear that there are significant problems in reducing the cost of small pitch LEDs (like 3mm).

Perhaps LED’s biggest problem is with “fill factor” – the area of the display actually occupied by the display pixel is small relative to the full display surface and this means that as the viewer gets closer to the screen, the image quality gets ‘pixellated’ and the quality of the image gets worse.

A rule of thumb that I believe LED display installlers have is that the MINIMUM viewing distance is around the same number of metres as the pixel pitch in millimetres.

For example, this means that effective minimum viewing distance of a 3mm LED screen is 3 metres, or 6 metres for a 6mm.

Then you probably need to add on a further 50% in distance to get a reasonable viewing quality.

Scrolling text LEDs in windows are surely a waste of time?

One Response to “LEDs in Windows – What Purpose do they serve?”

  1. TellerTV Says:

    I’m not sure the benefits (ie. the economics of awareness/showings) outweigh the costs, but I think the answer as to why banks and financial institutions continue to implement LED tickers is relatively straightforward.

    Banks and brokerages use LED tickers the way barbershops use rotating candy-striped poles–to attract attention and announce their presence to the passers/drivers-by. Given that an average branch costs 750 thousand to 1 million pounds to operate annually, and considering that the #1 factor in deposit market share is perceived convenience/location ubiquity within a market, if LED signage or other external treatments (backlit, awnings, etc.) can materially improve a branch’s visibility, as they have proven to do in limited testing, stateside, they are well-worth the relatively small operating cost they entail.

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