What digital signage really is

Digital signage means: screen surfaces in publicly or semi-publicly accessible places, centrally controlled, filled differently by time and location, designed for continuous operation. Four characteristics, and each one draws a line.

The television in the shop window meets none of them. It is built for a few hours of evening programming, not for ten hours of sun straight on. It knows no portrait format, drops into standby after a power cut instead of back into the picture, and can only be operated if somebody stands in front of it with the remote.

The video wall in the concert hall is the other extreme. It is stage technology: LED modules, an image processor, live feeds, a technician at the desk, built for one evening. That is not digital signage either, even though the same modules may be installed.

Between the two lies our field: an installation that starts itself in the morning, shows the right thing during the day, switches off in the evening and lasts for years without anyone checking on it daily.

Whether one surface hangs in a bakery or fifty in a retail chain: the building blocks are always the same. If one is missing, you will notice within three months at the latest.

Hardware and software are bought and done. Content and operation carry on, week after week, and decide whether the installation is still worth anything after two years.

The shop-window display works behind glass against daylight. Brightness and heat are decisive: below 2500 candela per square metre the surface loses out in sunshine, and a unit without heat management drops out in summer.

The screen on the sales floor has an easier time. Indoor lighting usually lies between 300 and 750 lux, so 350 to 500 candela per square metre is enough. What matters is placement: at the shelf, where the decision is made.

Totem and digital pavement sign are the mobile variants. They need no hole drilled in the façade and can be moved until the effect is right. What matters is stability, cable routing and, outdoors, ingress protection – at least IP54 against splashing water and dust.

The menu board in food service is a discipline of its own. It is read from three metres, by people in a queue who decide within thirty seconds. What matters is type size, a calm structure and the ability to change the offer day by day without opening a layout program.

The wayfinding system answers a single question: where do I have to go? Clarity and currency are decisive – a directory still showing the department from two years ago makes your building look unreliable.

Reception and waiting area are waiting places. Here content may run longer, here greeting visitors by name works. What matters is enough variety for eight minutes of waiting, without becoming frantic.

Hotel TV is a special case, because host and guest use the same device. The guest wants to watch television and stream, the house wants to show breakfast times, spa and weather. What matters is a system that separates the two and resets the room at checkout.

In the meeting room what counts is that the person walking in at eight connects their laptop and has a picture within thirty seconds; in between, the surface shows the booking from the calendar. In the production hall the key figures belong on the wall – units produced, rejects, days without an accident. What matters is large figures and a data source that is not fed by hand.

The LED wall is not a larger version of the display but a different construction: individual modules on a frame, any shape you like, up to the size of a building. Everything is determined by the pixel pitch, the distance between two light points in millimetres. Rule of thumb: minimum viewing distance in metres equals pixel pitch in millimetres. Indoors we are usually between 1.5 and 3 mm, outdoors between 4 and 10 mm, but there with 5000 candela per square metre and more.

Touch and kiosk reverse the direction: it is not the installation that speaks, it is the person who asks. Product search, checking in at reception, ordering terminal. What matters is a short first level, a return to the home screen after inactivity, and glass that can take a knock – on public devices we look at the IK impact rating.

Advertising network surfaces are the special case where the surface is not yours. The site provides the space, a network operator supplies technology and operation, advertisers book time slots. What matters is availability and proof that the booked playout actually ran.

This overview shows where the requirements diverge – and why a device that is fine in a meeting room will not survive one summer in a shop window.

Operating hours is the underrated column: 16/7 means sixteen hours on seven days and is the normal case for commercial displays, while 24/7 demands a different design of panel and cooling.

The idea is older than the screen. The light box in the cinema foyer and the slide carousel in the travel agency were digital signage without the digital: a surface in the field of view, content that changes.

Then came the cathode-ray television with a video recorder, later with a DVD on endless repeat. Anyone who wanted to change the content brought over a new cassette. In the 2000s the USB stick took over, and that image still shapes the idea of the advertising screen today: a television, a stick, someone driving round the branches.

The leap came with two developments. First the player: initially a PC under the display, then a small box, today mostly a system on chip inside the device itself – a computer behind the panel, with no extra box and no fan. Second, management in the browser: since content has been distributed over the network, it makes no difference whether a surface hangs in the same building or eighty kilometres away.

In parallel the hardware became more serious. Commercial displays tolerate continuous operation and portrait format, can be switched via RS-232 or CEC and report their condition. That is the difference between a device and an installation.

When I am asked what has changed in ten years, most people expect an answer about resolution: 4K, 8K, HDR. That is the least important part. From three metres you can barely see the difference between Full HD and 4K, and the two seconds from the first chapter do not get any longer because of it.

Two other things have changed. First, operation. A fault used to mean: phone call, drive out, swap the stick. Today we see in the management system that a device has not reported in since Tuesday, and usually the matter is settled remotely before anyone on site notices. Schedules, switching times and updates run without anybody driving anywhere.

Second, the content. A surface no longer has to consist of finished images. It can draw on your own sources – menu plan, calendar, stock levels, weather, key figures – and on templates into which your team drops text. That removes the reason most installations fall into neglect: that every change costs effort.

Technology is no longer the bottleneck. The bottleneck sits where it always sat – in the question of what should appear on the surface.