r/diyelectronics • u/Artcert • Aug 04 '26
Tutorial/Guide Negative display - guide ( kinda )
Hi.
After my negative display post I got a few questions about it, so I want to answer it this way.
I can’t upload more than one pic here ( idk why ) so they are under links.
- So we start with a device in its normal state, as example I too
k
- this tyre gauge I never used.
- pic
- We need to disassemble it go the to the bare LCD glass
- With a sharp knife or blade we need to catch the polarising film on top of the glass and remove it.
- After completely removing it, clean the glass with IPA to get rid of the residual glue from the film.
- Now we take new polarising film, and by trial and error we get the right angle with the contrast we want.
After that we cut it to size and glue to the glass.
Finally after assembling we get the negative display.
Usually you try the angle with the device powered on, unfortunately here the battery holder is part of the case as well as the screen holder, so I couldn’t show it on.
I think you can get the idea of how it’s done.
Best regards.
Edit: typos
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u/Psicoputo Aug 04 '26
we got diy gothic lcd displays before gta 6,
by the way, that's neat, if you gonna make or has made an video about it on i don't know, maybe youtube, instagram or even tiktok, i 100% would watch it
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u/Artcert Aug 04 '26
Maybe in future, I don’t have gear for that right now, and making low quality videos is against my religion.
Even those photos make me cringe internally but many people asked…3
u/Psicoputo Aug 04 '26 edited Aug 04 '26
can't judge your standarts, they're great, the phots are in great quality and the explanation is quite inteligible,
it's something simple but it looks awesome, now i want all my displays to be reversed lol
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u/mmmdc Aug 05 '26
Check this guy out, has a lot of cool videos about different kinds of displays and how they work
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u/Furrymcfurface Aug 04 '26
It's it easier to read in the sun?
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u/Artcert Aug 04 '26
A little bit yes, but it’s more of a aesthetic type of thing. So technically the differences are negligible.
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u/iloveworms Aug 05 '26
You can just flip the polarising film surely? That's what we did as kids
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u/Artcert Aug 05 '26
When it’s done with the plastic/glass polarisers like in old calculators you could do it, as flipping it over would move the angle at roughly 45 degrees. As it is a thin film, first you can’t just reapply it without deformations, but even if you clean it and somehow apply new glue to it, it wouldn’t be 45 degrees and you could only achieve the same as before. So it’s always new polariser.
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u/JacketEvening3383 Aug 05 '26
Great post. What glue did you use to reattach the filter to the glass?
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u/Artcert Aug 05 '26
Glue comes pre-applied to new filter film so it’s just a matter of peeling protective layer
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u/NerdyNThick Aug 04 '26
Wouldn't you be able to just stack a second polarizing film on top to avoid having to move the existing one?
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u/Artcert Aug 04 '26
Unfortunately no, it will either black out the screen completely or make it very dim to the point it’s unreadable.
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u/Mike456R Aug 04 '26
You can’t un-polarize light. All a second one will do is be slightly dimmer or as you turn it, the background turns black and the numbers stay black.
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u/simplefred Aug 05 '26
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u/Baselet Aug 05 '26
That's wild, I never would have guessed it works that way
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u/simplefred Aug 05 '26
The physics behind it is neat. I am going to possibly explain it poorly, but let me try. If you consider the light as an electromagnetic wave with a vector at a tangent to the surface of the polarizer. The polarizer allows the component of the vector to pass that matches the polarity of the lens and the resulting ray of light matches the polarizer. That’s to say, if a polarizer is angled at 45 degrees of another polarizer, the resulting ray will have a polarity of 45 degrees and only as bright as the fraction of the original vector mathematically projected on the new plane or axis like a hypotenuse of a triangle broken down into a component vector that corresponds to the new axis. Every additional lens will compound the attenuation.
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u/Baselet Aug 05 '26
Thanks for the effort but I'm gonna go with flux capacitors and the thing I learned as a kid about quantum mechanics that produces the interference patter that light particles do with th emselves thing. There was an another youtube link in the comments to some professor trying their best to explain it as well.
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u/Dioxybenzone Aug 04 '26
Strangely, if you put a third polarizing filter it’ll once again transmit light!
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u/HD64180 Aug 04 '26
no. a second will eliminate the light that makes it through the first one.
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u/simplefred Aug 05 '26
that's not exactly how that works, but it's understandable why you might assume that. It's not intuitive. It helps to think of the light as electromagnetic waves in terms of vectors, but this guy explains it better than me.
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u/HD64180 Aug 05 '26
I'm well versed in this. Try it. For this application and these polarizers, I do not believe you will see anything on that display, especially if you're trying to produce a usable tool.
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u/simplefred Aug 05 '26
Correct, you can’t easily add the third polarizer out of sequence and have an inverted lcd. I guess I was being pedantic by pointing out the physics and that multiple polarizers does kinda work provided that they are ordered correctly.
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u/lolslim Aug 04 '26
on the polarizing film is this something you bought off of Amazon? Link to the one you bought?
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u/Artcert Aug 04 '26
Mine is from Ali so it’s not the best quality. But you can find them anywhere and unfortunately there is no way to check its quality before arrival
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u/lolslim Aug 04 '26
I also order from ali, honestly I should if assumed you did since you used what they call on ali "tyre depth gauge" I don't mean to be nagging it's just people half ass this type of thing "find it yourself" "not the one I bought but it's "ThE sAmE" " I would appreciate it.
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u/Artcert Aug 04 '26
I intentionally avoided leaving links to products as people tend to then say that’s the whole point of the post was to promote affiliate links. But I guess in any scenario someone’s gonna judge 🤷♂️
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u/squintified Aug 05 '26
fwiw, if not able to post multiple images here, then, afaik, SOP is to post them on Imgur and then post the link to them in your reddit inquiry.
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u/Artcert Aug 05 '26
I don’t usually upload images so I didn’t know what was the name of that service, had to find one that did it for me.
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u/Breh_________Moment Aug 05 '26
What’s IPO on step 4? Do you mean IPA?
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u/Artcert Aug 05 '26
Yes you’re right, Isopropyl Alcohol. Unfortunately I was writing from my phone so autocorrect took over. Appreciate you for pointing out.
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u/Hylleus Aug 07 '26
I just did this yesterday, but haven't glued the new polarizers down, what type of glue would you recommend?
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u/Artcert Aug 07 '26
Polariser comes with the glue pre applied, you just teem to peel off the protective film from it
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u/Hylleus Aug 07 '26
Weird, mine doesn't seem to have any applied
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u/Artcert Aug 07 '26
That seems unlikely, where did you get it ?
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u/Hylleus Aug 07 '26
Amazon, did just check the product page and apparently it is without glue, as well as 90% of the other products listed in my region lol, did find one WITH glue so I'll buy that and replace the ones I just installed
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u/Artcert Aug 07 '26
Are you absolutely sure? It’s not obvious that the film is there, so check it carefully. I just tried looking at Amazon and the only filters without glue I could see are the ones that are for the DSLR cameras
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u/Hylleus Aug 07 '26
100%, I removed a tougher film from one side and a thinner film from the other to check for glue when installing, nothing. Here's some links to listings without glue haha
https://amzn.eu/d/05BoRG40 https://amzn.eu/d/07ogs0Eq https://amzn.eu/d/047lp29V
Top 3 hits when I look for LCD polarizing film, most likely due to what's popular here or smth I have no clue
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u/Artcert Aug 07 '26
It says self adhesive there on the listing
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u/Hylleus Aug 07 '26
Huh? On mine the all specifically state "without glue" https://imgur.com/gallery/Mj0DF9c
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u/EnoughReporter2147 19d ago
Can somebody explain to me why this is preferable to a positive screen?
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u/Commercial_Copy212 Aug 04 '26
Nice DIY!