How to attach the touchscreen to the display

[cypher]

Dear all,

I use the A13-LCD7-TS display , but until now only the lcd without the touchscreen.

I don't know how to attach the touchscreen to the lcd. Which kind of glue should i use?

Super glue? Or have somebody a better solution.

Best regards

Marc

[David Goadby]

I am planning to use the LCD with the touch panel in an aluminium console panel. I don't like the idea of gluing the touch screen to the LCD I do not know what the effect of an adhesive on the glass/plastic might be. I did think about double sided tape but the thickness is a problem at the edges.

My current solution is to use a plastic bezel inserted into my aluminium front panel with a rear recess that locates the touch screen and the LCD as they are the same size. I then have six integrated clamps; two along the long sides and one along the short sides. The clamps press on the rear of the LCD display and keep the whole assembly tight.

I am looking at having a 3D printed prototype made to see if it works in practice. If there was enough demand I may do a run of them for resale. With a plastic bezel the edge clamps will be incorporated. I am going to need 100 for a project so costs may not be too bad.

The only concern I have is whether I need a protective layer in front of the touch panel in an industrial/damp environment. I am looking at a thin vinyl layer but I need to stretch it so it doesn't go "baggy". As the touch panel is resistive, adding another layer doesn't affect performance very much but does drop the display brightness. Hopefully I don't need it and, at 55 Euros it's probably not worth the effort.

As I write, the development unit is located in a temporary frame made from 10mm aluminium angle milled to size on the front side and with a few blobs from a glue gun on the rear. It's a little better than rubber bands! ;-)

[jess]

Not sure if it gets any attention but just in case David still reads it...

Did you managed to manufacture your plastic bezels for 7" screen?
If yes, can you (or somebody who did) post the results?

Or perhaps there's another custom or off-the-shelf way to do it. Please share your findings.
I'm new to this and trying to figure out the easiest yet reliable way of mounting the 7 inch resistive touch screen combo to front panel without duplicating your efforts.

Thanks,
John

[David Goadby]

Hi Jon,

I managed to mill one out of aluminium as a proof of concept. It was really a copy of a similar product I have on test but it did work. I wanted to progress to a lower cost small plastic production version but I have stopped for now. The project I am working on needs a Linux system with a touch screen and running WxPython. At this time, although a few folks have managed to put a system together that seems to work, they all involve a lot of kludging. I need a ready-to-go downloadable image that works right out of the box - preferable validated by Olimex. Until that happens I am having to use a really expensive alternative (Embedded Arm)) in order to get my customer happy.
When I get back to it I will post here again.

David.

[jess]

Thank you David and I'm glad you found time to reply with some additional info. My efforts to connect the 7" touch screen were semi-satisfactory as I managed to ruin one screen when trying to replace a damaged (scratched) top touchscreen part of it. Mind you I was originally using a double sided sticky tape that kept both parts so hard together that the touchscreen broke into pieces during my trial to disassemble them.

I wonder if Olimex can make it easier for us and start selling a complete screen joined professionally together. Plus perhaps some kind of plastic bezel that keeps that combo safe and happy
Or perhaps even a tablet size enclosure to match the screen size.

I guess that moderator (OLIMEX) can move that last part of my email to wish list section.

Thanks,
John

[tuxglux]

hey there,

getting my case for a13-wifi with 7" this week from fabberhouse. If it fits the screen and touch i'll let you know it. maybe i'll upload some pictures.

[jess]

Yes! 3D-printing... now we are talking

[David Goadby]

I did consider 3D printing and have access to a Makerbot but I thought that the final finish might not be good enough. Some pictures of your bezel would be interesting to see.

My son has a cnc laser cutting machine that cuts plastic. He is going to cut a polycarbonate bezel for me and I will see how it works out. The mounting lugs will be added afterwards using a solvent adhesive.

The LCD/touch screen is clamped to the aluminium front panel with countersunk screws that are hidden by the bezel. I have also tried a clear mylar over-cover to improve IP rating and it doesn't upset the touch screen too much.

David Goadby

[jess]

David, I still wonder what exactly did you place in-between the touch and LCD screens - did you still use a double sided tape or placed something else just to keep a gap? Can you just lay it down on top of each other without any gap?

[Lurch]

I used a thin layer of rubber cement (painted on with a small brush) and that worked fine.
The touch screen doesn't need a gap. It wasn't as much of a problem as I thought it would be.

[David Goadby]

I used a Scotch Magic tape along the edges. There is no need to maintain a gap to the glass. Once clamped it doesn't creep and you can separate the panel from the LCD easily with a razor blade. I run the tape along the full length of all four sides and this creates a gasket to seal with the panel.

The friction of the tape against the aluminium panel also stops it sliding around after fixing; it never moves.

I also tried added a fillet of silicon sealer along the edge after clamping to improve IP rating but I found that the Scotch tape on it's own sealed very effectively.

Regards

David Goadby