A QR code on digital signage is a way of showing a QR code on an electronic sign (digital signage) installed in places such as train stations or shops, so that viewers can scan it with their smartphone and be sent from the sign to an online page. Unlike a paper poster, the content shown on the screen can be swapped out at any time, so the biggest advantage is that you can frequently update the destination and the way it is presented to match a running campaign or current stock levels.
A common approach is to switch the link destination by time of day. For a restaurant, you can send visitors to the reservation page for a morning menu in the morning, a lunch menu at midday, and a dinner menu in the evening, all while keeping the same sign and the same QR code and changing only where it leads. This works because, if you embed a short URL in the QR code, you can change only the destination on the server side without swapping out what the sign displays.
It also pairs well with out-of-home (OOH) advertising. By counting how many times a QR code shown on a sign inside a station or a commercial facility is scanned, you can get a rough sense of a display's effect, which used to be hard to measure. You can track how many times each sign was scanned and how many of those people went on to apply or make a purchase, which gives you a clue for comparing the cost-effectiveness of each sign.
When you want to look at the effect in more detail, the basic approach is to assign a separate short URL to each sign or location. By comparing how each combination of location, time of day, and design is scanned, you can work out which displays tend to draw a response. If you attach a parameter that identifies the source to the short URL, it also becomes easier to separate the paths in your access analytics tool.
A common pitfall is the appearance of the QR code and the environment where it is placed. If the code is too small for the viewing distance it cannot be read, and glare or reflection on the screen can hide it. On signs where the video changes, the QR code is often displayed for too short a time, so it disappears before a passer-by can even raise their camera.
To make the code easier to read, it is important to secure a size that is large enough for the viewing distance, choose a display position that keeps reflection down, and set an appropriate error correction level so the code can still be recovered even if it gets somewhat dirty. Embedding a long URL as it is makes the code complex and hard to read on a small display, so keeping the amount of data down with a short URL makes it easier to design something that reads reliably even in a limited screen area.
A QR code printed on paper cannot have its destination changed once it is printed, whereas the decisive difference with a digital signage QR code is that both the display and the destination can be adjusted later. Even if the campaign changes after the sign goes up, or you rebuild the linked page, you can handle it just by swapping the forwarding target of the short URL, so the longer a display is meant to run, the easier it is to manage.