…There’re two things to take into consideration when you want to use LEDs as an output in a product:
First light can only shine at a right angle of the PCB; or alongside with the electronic board if you use 90° type of SMT LEDs. In case you want to reach a location of your product which isn’t directly aligned with the board you will have to buy, or have made, a LED pipe that will conduct the light to the right place.
The second role of a led pipe is to act as a diffuser; i.e.: the light is guided with minimum loss and, at the end, spread equally on the surface of the casing. This is accomplished by polishing the end of the pipe.
…In our case we wanted the light to be visible from all angles and spread out equally over 360° horizontally. To achieve a light ring usually you design a circular PCB with many LEDs and you have a diffuser right in contact with them.
We couldn’t afford to have a special LED board so we had to have the LEDs on our vertical PCB. Also we couldn’t afford to have a ring piece that we would need to polish by hand.
So we had to conduct the light as equally as possible to the edges and then to diffuse it. For both functions we used light reflection by having a kind of gear teeth pattern laser cut in our transparent pmma. We tested several design and found out that it was by having one gear pattern close to the LEDs and one at the edge that it work out the best to have a relatively equal spread of lighting….
Eink, E-paper, Think Ink – Collin shares six segments pondering the unusual low-power display technology that somehow still seems a bit sci-fi – http://adafruit.com/thinkink
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