Edge lighting
Edge lighting (edge-lit) means a light display is lit not from behind but from the edge. The LEDs sit all around the frame profile and shine across the surface from every side. The translucent banner fabric is lit through and glows evenly – with no LEDs behind the image area at all. This saves space and keeps the construction flat and light.
The lenses make the difference
To make a surface equally bright right across from the edge, an ordinary LED is not enough. Special diffusing or wide-angle lenses are used to spread the light flat and wide across the whole area – all the way to the centre, which is furthest from the LEDs. Without these lenses the edge would be glaring and the centre dark. This lens technology goes back to a patented development by Philips; using these LED systems therefore incurs a licence fee that is included in the product price.
Why ordinary LED strips do not work
A standard LED strip shines its light straight forward and only over a short distance. For edge lighting a larger frame this is unsuitable: the light simply does not reach the centre. The result would be bright edges and a dark „tunnel" in the middle – or visible light-and-dark stripes (hotspots). That is why we use lens LEDs with a controlled light distribution, not standard strips.
A certain frame depth is essential
Light from the edge needs some distance to spread out. Inside the frame profile it first has to fan out and mix before it hits the fabric. For this the frame needs a minimum depth. If it is too shallow, the light cannot spread evenly and the illumination becomes patchy. Our LEDUP systems, for example, have a profile depth of around 80 mm – enough for clean edge lighting. Very shallow frames cannot be sensibly lit from the edge; there a full backlit solution is used instead.