Weird squiggle on 20x4 LCD - Page 1
Forum section: electronics / general

author: greencardigan
author_rank: Contributor
timestamp: September 16, 2023, 07:43:41 am
content: Anyone know what would have caused this weird squiggle on my LCD?It wasn't there a few weeks ago when I last used my roaster controller.

author: DavidAlfa
author_rank: Super Contributor
timestamp: September 16, 2023, 08:02:56 am
content: No idea. Seems like damage to the polaryzer film.Perhabs some solvent dropped on it?Maybe made by realtek, slowly showing up,In any case it needs a new LCD, thankfully inexpensive.You have some with cool colours here:https://a.aliexpress.com/_EwZ5zBv

author: AVGresponding
author_rank: Super Contributor
timestamp: September 16, 2023, 08:35:27 am
content: The polariser is made with iodine crystals in a polyvinyl alcohol film. Heat, and damp, can both cause degradation. A slight contamination during the manufacturing process can probably act as a nucleation point.The film can be replaced, but it's a fiddly job.

author: jpanhalt
author_rank: Super Contributor
timestamp: September 16, 2023, 08:55:04 am
content: Something similar is discussed here:https://www.eevblog.com/forum/beginners/why-i-do-not-like-fractals-on-my-lcd/msg4748645/#msg4748645It obviously some defect. Another possibility suggested in that thread is a fungus.

author: AVGresponding
author_rank: Super Contributor
timestamp: September 16, 2023, 10:05:19 am
content: Quote from: jpanhalt on September 16, 2023, 08:55:04 amI'd be surprised if it's a biological vector, iodine is pretty good for sterilising things.

author: jpanhalt
author_rank: Super Contributor
timestamp: September 16, 2023, 10:41:49 am
content: I simply mentioned it as having been discussed here before. Personally, I would lean more toward a crystallization artifact perhaps from decomposition of the PVA. As for fungi actually growing in iodine, I agree that iodine is/was widely used as an antiseptic, particularly its complex with PVA. However, a fungus growing between layers would not be exposed to it.Bottom line: There is no definitive answer and those bothered by it, so far as I can tell, have not investigated it further. Disassembly and microscopic examination to identify which layer is affected would seem to be a first step. If it is in the polarizer, there are simple things that could be done to help pin its cause down.

author: greencardigan
author_rank: Contributor
timestamp: September 19, 2023, 01:00:46 pm
content: Quote from: jpanhalt on September 16, 2023, 08:55:04 amThanks. That does look like the same sort of thing.I'll have to keep an eye on it and see how quickly it's 'growing'.

author: eutectique
author_rank: Frequent Contributor
timestamp: September 19, 2023, 03:39:03 pm
content: Resembles the tooth marks of a gastropod

author: greencardigan
author_rank: Contributor
timestamp: August 07, 2024, 06:22:34 am
content: Just for the record. It's still growing slowly.

author: tom66
author_rank: Super Contributor
timestamp: August 07, 2024, 07:58:32 am
content: I have a TI-84 Plus that has the same kind of defect, but it is black pixels that are 'growing'.

author: Psi
author_rank: Super Contributor
timestamp: August 07, 2024, 08:01:24 am
content: Yep, looks biological to me.Probably had some bacteria trapped inside during assembly and it just so happened to have enough food and light to grow for a short time.If you mask it and hit only one side with some bright UV you might be able to prove it's bacteria if only the other side continues to grow.

author: H.O
author_rank: Frequent Contributor
timestamp: August 07, 2024, 12:11:44 pm
content: Myfx-9750Ghas the same sort of thing. Always there no matter if the calculator is on or off.It came that way when I bought it second hand a while back, I have not (yet) noticed it growing but now I'll keep a close look it just out of curiosity.

author: Buriedcode
author_rank: Super Contributor
timestamp: August 07, 2024, 07:12:27 pm
content: I have several displays with these - all of which are old, 20yrs+. I just assumed it was a delamination of some kind.

author: SiliconWizard
author_rank: Super Contributor
timestamp: August 08, 2024, 12:17:58 am
content: Looks like a pretty standard 20x4 LCD which you shouldn't have any trouble replacing.

author: AVGresponding
author_rank: Super Contributor
timestamp: August 08, 2024, 01:06:14 pm
content: Quote from: Psi on August 07, 2024, 08:01:24 amIt's not bacteria. Here's a picture of a (simulation of) fractal percolation growth in porous glass and microemulsions:A brief excerpt:In any case, many bacteria are resistant or immune to UV:https://www.nature.com/articles/s41598-023-40996-8

author: jpanhalt
author_rank: Super Contributor
timestamp: August 08, 2024, 05:44:47 pm
content: Quote from: AVGresponding on August 08, 2024, 01:06:14 pmThe paper cited in your link seems to say the opposite. Your link says:QuoteReference 9 is cited for that statement. It reads:QuoteOf course, some microorganisms are more susceptible than others to UV. Simply shining a UV light on something doesn't mean that something is actually exposed to the UV. Absorption by intermediate materials (window glass in some cases or cornified epithelium as in the Nature paper) can protect underlying things/tissues from being affected.

author: AVGresponding
author_rank: Super Contributor
timestamp: August 09, 2024, 10:09:57 am
content: Quote from: jpanhalt on August 08, 2024, 05:44:47 pmYou clearly haven't understood what they wroteat all."There is currently no evidence that pathogen resistances or tolerance can be induced following to UV-C irradiation" means that non-resistant strains do not become resistant by being exposed to UV-C, in lab conditions. It saysnothing whatsoeverabout extant resistant strains, but implies that UV resistance may be a complex mutation that doesn't happen easily.This is a good thing in context, as it means UV sterilisation in labs/hospitals etc is unlikely to pose a risk in regards to resistance mutation.As to the second point, that UV is easily blocked and therefore using it in this case may be ineffective, that only reinforces my point that exposing these displays to UV in an effort to "sterilise" them is unlikely to be useful, even if the problem is a bacterial one and not one of fractal percolation of dielectric relaxation.

author: e-pirate
author_rank: Regular Contributor
timestamp: September 11, 2024, 10:23:00 pm
content: Just noticed same thing on my decade old Ohaus Traveler weight:In my case device was always stored in cardboard box out of light.Have no idea how to fix that - the LCD looks like a custom Ohaus job.

author: BennoG
author_rank: Frequent Contributor
timestamp: September 17, 2024, 06:58:04 pm
content: this is also know as lcd screen cancer. As far as I know you can not do much about it.I have a 600 euro detector that has the same problem, only not with a standard display, so I have to live with it. It has been growing slowly over the last 5 years.Benno

author: reboots
author_rank: Regular Contributor
timestamp: September 17, 2024, 07:12:52 pm
content: Just chiming in that I had several identical older devices with graphical dot-matrix LCDs which showed this exact effect to a varying extent. I believe I recycled them all, but it would have been interesting to experiment with removing the polarizing film. Heat gun would probably work, but the glass panel might not like it.

author: daisizhou
author_rank: Super Contributor
timestamp: September 18, 2024, 12:22:36 am
content: Quote from: greencardigan on September 16, 2023, 07:43:41 amChanging to white backlight and black display is the best choice. It's time to make an upgrade.

author: BennoG
author_rank: Frequent Contributor
timestamp: September 18, 2024, 06:36:52 am
content: Added some photo's of my display.The last photo is from 2017 when everything was still ok.Ik I can find a photo from around 2020 2021 or so I will add it.So you can see how it grows.Edit OK 2022 had the same damage so it stopped and is not growing anymore for the last 2 years

author: greencardigan
author_rank: Contributor
timestamp: August 14, 2025, 03:51:47 am
content: Another year has passed, and another slight increase in coverage. It seems to have slowed down a lot though.Thanks all for the interesting info and other examples.Quote from: SiliconWizard on August 08, 2024, 12:17:58 amYeah, I even have plenty of spares, but it hasn't affected any areas of the LCD that I use yet, so I'll let it do it's thing for now.