Aura HD Screen Freeze

[Ken Maltby]

Originally Posted by DNSB

When I look at my Aura, between the bezel and the screen, there is a narrow space which is set a millimeter or so back from the edge of the bezel. I had assumed that the plastic on the back of the gap was an IR filter which covers the emitters on one side and the receivers on the other side of the Aura (ditto for top and bottom of the screen). I have noticed that if anything gets into there (cat hairs, for instance), the touch screen can behave very strangely.

Regards,
David

Well, that must be the problem, my bezel has no such "gap" and it is all
one piece of plastic. There is no observable space between the top sheet
of plastic and the bezel, in fact there is a layer of double sided tape that
secures the inside edge of the bezel to the top layer. It would be hard to
picture how a cat hair could cause a problem but double sided tape not.
In any case there is no electronics in the bezel. There is nothing above
the top layer of plastic. There is a black layer two or three layers down,
perhaps that means something?

Luck;
Ken

[Ken Maltby]

I do appreciate that you are trying to help the OP.

I guess I was just unaware of the fragile nature of IR Touchscreens. If it is this bad,
how can you stand it? I would much prefer a capacitive, or even resistive Touchscreen,
to one so easily put out of commission.

Maybe I should regret my purchases of the Kobo Aura HD? Killed by a cat hair, whod'a
thunk?

Luck;
Ken

[TechniSol]

I thought your Aura was killed by the guy who disassembled it?

I'm not sure about the Aura(but it seems reasonable to expect), but the Touch and Glo both have a layer of IR transmissive plastic around the edges of the screen, between the top layer of the screen and the bezel that allows IR to be projected and sensed just over the screen layer. When you "touch" the screen you interrupt these beams just above the screen surface.

I had a look at your thumbnails. From them I suspect there is a layer of IR transmissive plastic in the bezel that bends the IR projected from behind the screen around it's edges and bends it so it projects back inwards over the screen. Put the bezel back on your Aura and the Touch should work again as long as you don't block any of the IR when you reassemble it. If you go to the website for the maker of the IR system they show a newer system that bends the IR around the edges of the screen as I described.

[sucah]

This pictures show the IR path on Glo.

https://www.dropbox.com/s/5p4r0dkju1...%20%281%29.JPG

https://www.dropbox.com/s/hdegjjzhxg5zlty/photo.JPG

[Ken Maltby]

Yes, in my case I think the IR transmitting was killed, in the course of handling the Aura
outside its case.

It would make sense that the bezel's inside surface could reflect the IR beams as you
describe, I'll try to clean off the tape residue and any other contaminates, and try to
see if that gets mine working. I may need to have a spacer of some sort to makeup
for any spacing the tape might have supplied. In any case, this not working would
not disprove what you are saying, as it could still be that I killed the actual IR transmission.

Luck;
Ken

[Ken Maltby]

Ok, I found what you all have been talking about. The bezel is not one piece of plastic,
it is two. If you are looking on the inside of the bezel at the corners you can see where
the two are separated some. The black inner piece would be the IR transparent part
that bends/reflects/guides the IR beams. That layer does sit back a little from the inside
edge of the top piece, forming the little gap talked about earlier. I can see where any
obstruction in that "gap" that blocks the IR beam coming off the edge of the black IR
guiding plastic could cause problems. The same would apply to an obstruction between
the IR emitters or receivers and the scalloped portion of the black plastic.

So far, a careful cleaning has not restored my Aura's touchscreen functioning.
It is too bad that I have no reliable means to establish whether the IR beams are
present at all.

I now see how the advice given earlier could be a fix.

Luck;
Ken

[filmo]

Small cylindrical security camera with IR lights might let you see IR light from Kobo IR touch system. They are fairly common now. Web search for other options.

Home inspectors sometimes have thermal imaging viewers to see slight temperature changes caused by gaps in insulation or air leaks are not as common or cheap but should also see the IR beams.

[jiminrussell]

Originally Posted by filmo

Small cylindrical security camera with IR lights might let you see IR light from Kobo IR touch system. They are fairly common now. Web search for other options.

Home inspectors sometimes have thermal imaging viewers to see slight temperature changes caused by gaps in insulation or air leaks are not as common or cheap but should also see the IR beams.

I have one of those cameras and I tried taking a picture of my Aura HD, I can't see the infrared pattern on the screen but I can just barely pick up where the infrared source lights are under the bezel. They look to be spaced about 1cm apart.

[Ken Maltby]

As it happens I am expecting 4 regular security cameras and a PTZ by the end of the
week.

Jim; did you notice which side and whether the top or bottom have the emitters?

Luck;
Ken

[jiminrussell]

Originally Posted by Ken Maltby

Jim; did you notice which side and whether the top or bottom have the emitters?

Luck;
Ken

That shot is of the top, will see if I can get a similar shot of the sides and bottom to see if they have emitters as well.

Edit: There are emitters on all four sides, they must be slightly offset so there would be a very tight pattern of lines going across the screen. That or some of the light sources are reflected light, I really can't be sure but they look like light sources.

Note the larger light spots are reflections from the red light source on the camera itself.

[filmo]

You can't see visible light beam in air unless it hits your eye directly, or is reflected off smoke, dust, or something to your eyes, and this should be true for IR light pattern over Kobo screen using IR camera.

[Ken Maltby]

Originally Posted by filmo

You can't see visible light beam in air unless it hits your eye directly, or is reflected off smoke, dust, or something to your eyes, and this should be true for IR light pattern over Kobo screen using IR camera.

Where's Hudson Hawk when you need him?

Luck;
Ken

PS; Good point I'll try to remember that when my cameras get here.

[TechniSol]

I believe there are emitters on one side and detectors on the other side opposite on both x and y axis. They could be staggered, but I see no benefit to that. The idea would be to rapidly pulse each emitter and then check for reception on the other side. If no signal is received on a particular sensor then you immediately scan the other axis to form a coordinate pair. This scanning is performed at a very high rate of speed. If you are detecting multiple inputs I suspect you would complete one axis scan and then the other noting each break. Now how you associate which x break with which y break I am clueless... Maybe with multi touch the only importance is figuring out whether the coordinates are converging or diverging like a pinch zoom gesture? I suppose it matters not as Kobo has(will?) not implemented multi-touch on their readers.

I would try just a little smoke to reveal the IR with the appropriate camera. Maybe hold it over a stick of incense or the like? I imagine it would need to be pitch black to see it as it's got to be pretty low power stuff and FAST.

Hudson Hawk! You're a man after my own heart, Ken. I can see you humming "Swingin' on a Star" as you disassembled that brand new Aura! ;p I completely fail to understand how people didn't get that movie.

[andrewjknox]

Originally Posted by DNSB

The IR senders/receivers are above the screen. If you get something into the gap between the screen and the bezel, you can block one of the IR beams. If you touch the screen elsewhere, it will be detected as if you were touching the screen in two spots simultaneously. Cat hairs work great to trigger this issue.

Regards,
David

Cats... of which I have two. And cat hair is the bane of my life...

Another screen freeze so looks like I'll have to exchange for another (just to cover myself in case it's something else entirely) before my 30 days are up with the retailer...

[Ken Maltby]

My IR cameras arrived today and if I angle it just right, so their is no reflection from
the camera's own IR emitters, I can see the spaced dots like those posted.

Well it looks like another cleaning is in order.

While I didn't spray any coating inside the bezel, maybe some got in while I was
coating the outside in 6 coats of "Plastic Dip"

Luck;
Ken