Disclaimer: Since this mod involves disassemblying the parts of the device the way you shouldn't, i don't take any responsibility. But any curious person with adequate electronics repair experience could handle this mod easily.
Looking at the kapton tape which looks in amber color, i wondered if i can use that slick tape to filter out blue light coming from the leds of the frontlight. Since the tape is so thin, it would fit virtually anywhere without difficulty in the device.
So i took apart my aura hd to give it a try, and it worked flawlessly.
Since this is not a mod for every user, and it is simple for those who can do it, i'll just post a few photos to show how i did it.
-take your front bezel off
-seperate display from front bezel, it is fixed with double sided tape, if it is your first time, get help from some heat and use soft thin tools like credit cards to pry between them.
-there is a flexible printed circuit board strip with leds under it, right below the visible display area, pry that off too. take a bit caution here since you can damage if you bend solder pads of the leds breaking them. you could also damage the cable going to the mainboard. mine started flickering after wiggleing it around, don't panic yet if this happens to you, i fixed mine by reseating the frontlight connector.
-you'll see to layers on the delicate e-ink display, the one on the top is the anti glare film, the one in the middle is the frontlight layer.
-put a strip of narrow kapton tape covering the step between the frontlight and the e-ink screen. this step is where the leds seat and you can see the five grinds on the edge to diffuse the light from leds, you have to cover them with tape.
-you can try to bend the tape with a spudger or a spatula to perfectly seat over the step to leave the led cavities less obstructed, but since the edges of the screen is covered with some rubbery material, the tape wont stick to it.
-cut the excess tape on the edges
-reseat the led flexible ribbon over there, first by placing the led side, making the leds touch to the edge of frontlight layer.
-reseat the front bezel.
-done.
the color is not the best, it has some greenish hue, but it is better than cool white for me, since i only use frontlight at night. i also heard somewhere that green light is much more easier on your eyes, and i used green text over black background for extended periods in the past, it was very comfortable.
if you can find a better light filter tape giving out proper warm color, you can use it too. inform me if you find one.
if you are concerned about the color of the light, you can try it before taking your device apart, putting some kapton tape over your phone flashlight, and then illuminating your kobo screen with that. the color will be EXACTLY the same.
i think this mod applies to any other front-lit e ink device, try and share your results.
here you see where you need to place the tape:
http://imgur.com/bQRGuRa
showing the cut edges:
http://imgur.com/7f3Vvpm
this is an image from my first trial, the tape placement is totally wrong but it gives you an idea about how to fold the tape inside the step between the frontlight layer and the display itself:
http://imgur.com/LavB3IF
here you see the led flexible strip put back in its place correctly:
http://imgur.com/13HBu7F
i couldn't image the proper color of the screen after installation due to white balance problems, but it is something between those to images:
http://imgur.com/hcvNljg
http://imgur.com/iinRVon
in comparison with ambient light only:
http://imgur.com/VrETK1U
good luck!
edit: below are the images of kapton tape vs. proper warming gel filter, you can clearly see why it doesn't give proper warm ight. you can also try those gel filters too, but kaptop tape is much easier to find.
![]()
![]()
