EEVblog #898 - LCD Contrast Experiments - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: July 07, 2016, 11:03:16 pm
content: What is the difference between LCD viewing angle and bias angle?How does adjusting the LCD bias voltage effect the display?What is LCD Ghosting?Also a demonstration of Photoelastic Birefringence in polycarbonate plastic display covers.Dave investigates the Liquid Crystal Display viewing angle problem in the EEVblog BM235 Multimeter.

author: imidis
author_rank: Frequent Contributor
timestamp: July 08, 2016, 12:56:40 am
content: Awesome! Thanks for trying it.

author: nidlaX
author_rank: Frequent Contributor
timestamp: July 08, 2016, 03:40:37 am
content: Very nice Dave! For your customers, will it void their warranties if they choose to change the bias resistor?I'm tempted to do this for my Greenlee DM-510A, but I'm almost certain the warranty will be void if I do.

author: GEuser
author_rank: Frequent Contributor
timestamp: July 08, 2016, 04:18:19 am
content: Good one Dave , i dunno where you find the time .You forgot though to turn on the backlight at the end to see what happens .

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2016, 04:52:58 am
content: Quote from: GEuser on July 08, 2016, 04:18:19 amYep, I forget a lot of things.

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2016, 04:53:41 am
content: Quote from: nidlaX on July 08, 2016, 03:40:37 amNot unless the mod demonstrably caused the fault.

author: Brumby
author_rank: Unknown
timestamp: July 08, 2016, 05:07:33 am
content: Good to know.Then again, people who purchase a product like this are more likely to have the skills to make such a mod. I know I could - but, at the moment, I have no plans to fix the backlight buzz nor contrast. This might change if a situation arises where there is a clear benefit - but I'm not into mods for the sake of mods.

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2016, 05:09:47 am
content: Quote from: Brumby on July 08, 2016, 05:07:33 amI won't bother modding my own lab units, doesn't cause an issue for me.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: July 08, 2016, 05:21:48 am
content: The polarizing effect is due to the crystallization of the plastic housing, polarizing filters are used to check for the internal stresses and melt flow properties of these kinds of plastics, if you look at the effect through the filter, you can actually see it shows where the injection moulded fill points where (the gates), but normally you would not see this at all unless you are looking through a polarized filter, such as sunglasses, etc.

author: TheDefpom
author_rank: Frequent Contributor
timestamp: July 08, 2016, 05:35:37 am
content: I think I will have a look at my one and decide if I should replace that resistor or not.

author: f4eru
author_rank: Super Contributor
timestamp: July 08, 2016, 01:10:42 pm
content: Wov !!Dave made a demo of the Davecad V2.0 in this video, with animation features !Innovation in the CAD fieldI hope this V2.0 will be released soon

author: EEVblog
author_rank: Unknown
timestamp: July 08, 2016, 01:20:51 pm
content: Quote from: f4eru on July 08, 2016, 01:10:42 pmBig announcement video coming shortly, I've sold DaveCAD to a large CAD company who shall remain nameless right now. Will post it from my new private island.

author: nctnico
author_rank: Super Contributor
timestamp: July 08, 2016, 02:23:13 pm
content: Quote from: EEVblog on July 08, 2016, 01:20:51 pmLet me guess: Staples?

author: Macbeth
author_rank: Super Contributor
timestamp: July 08, 2016, 02:44:58 pm
content: I am in awe of the new DaveCAD transparent animation plugin. Patent it before Solidworks steal it for themselves!

author: Brumby
author_rank: Unknown
timestamp: July 08, 2016, 03:33:09 pm
content: Sorry I didn't comment earlier, but I, too, was impressed by the animation plugin!Looks like it can handle multiple layers as well. Impressive.

author: Hootch
author_rank: Contributor
timestamp: July 08, 2016, 03:44:02 pm
content: Quote from: EEVblog on July 08, 2016, 01:20:51 pmYou just revealed it: 3M

author: rrinker
author_rank: Super Contributor
timestamp: July 08, 2016, 06:16:29 pm
content: Quote from: EEVblog on July 08, 2016, 01:20:51 pmAltium owned an ISLAND, too?

author: Howardlong
author_rank: Super Contributor
timestamp: July 10, 2016, 04:58:42 pm
content: 39k on my two units, 20k was an improvement, but 39k much better.

author: BobC
author_rank: Unknown
timestamp: July 10, 2016, 08:27:57 pm
content: Trap for Young Players: When purchasing a device for outdoor use, always take it outdoors and view it while wearing your polarized sunglasses!Way too many displays need to be turned sideways to be legible when wearing polarized glasses. I haven't seen the problem in my recent multimeters, but it was present in some older ones.The first Android phone I purchased, an LG L9, worked great outdoors at all orientations (I still need to figure out how they pulled that one off). But I forgot to check my next phone, a Samsung Galaxy Avant, and it turned out to be viewable only in portrait orientation, which fortunately works fine for Google Maps, but not for any of my fitness tracking apps. Arrgh!

author: amyk
author_rank: Super Contributor
timestamp: July 11, 2016, 01:44:24 am
content: Quote from: BobC on July 10, 2016, 08:27:57 pmThat's because some of them use 45-degree polarisation while others are 0/90.http://electronics.stackexchange.com/questions/28113/why-are-lcd-panels-polarized-at-45-degreesAnd of course those using OLED will be visible at any angle.

author: Brumby
author_rank: Unknown
timestamp: July 11, 2016, 03:10:55 am
content: Quote from: BobC on July 10, 2016, 08:27:57 pmYes, the polarization experiment needs to be done before purchase.An aside.... I remember walking down the street one day wearing my polarized sunnies when I spotted a woman walking in the opposite direction wearing hers. The only trouble was, with her glasses one lens was clear and the other was black and a quick tilt of my head confirmed hers were polarizing. I expect one of the lenses had been put in 90º out of whack - which was possible because they were perfectly circular. I wonder if she ever had a glare problem with her left eye.......

author: amyk
author_rank: Super Contributor
timestamp: July 11, 2016, 10:23:34 am
content: Quote from: Brumby on July 11, 2016, 03:10:55 amShe'd probably see the same thing and wonder whyyourglasses had the lenses wrong...

author: LazyJack
author_rank: Frequent Contributor
timestamp: July 11, 2016, 10:35:38 am
content: Quote from: BobC on July 10, 2016, 08:27:57 pmYeah! Trap indeed. This is something a lot of marine instrument manufacturers still need to learn. On my boat, when wearing polarizing sunglasses (practically all the time, when it's not dark around) I need to constantly tilt my head back and forth to either see the depth sounder or the autopilot display.But I've been to cars, where various displays, like radio and A/C did not have the same polarization, so one of them was always black in polar glasses.

author: bktemp
author_rank: Super Contributor
timestamp: July 11, 2016, 11:08:27 am
content: Quote from: amyk on July 11, 2016, 01:44:24 amFor OLEDs itself this is true, but there are sometimes polarizers added to the display to reduce glare.

author: Brumby
author_rank: Unknown
timestamp: July 11, 2016, 12:43:10 pm
content: Quote from: amyk on July 11, 2016, 10:23:34 amNot sure about that. Her left eye would see my glasses as being black on both sides and her right would see them as clear. With binocular vision, these two images would be overlaid in the brain and the problem would not be immediately obvious.Her left eye, however, would not have been getting the protection of polarizing filtering in the normal plane.

author: vince53
author_rank: Contributor
timestamp: July 11, 2016, 02:36:10 pm
content: Good work Dave,I have noticed the contrast issue but have gotten around it by using the backlight all the time. I'll get around to making the mod.Thanks,Vince

author: Porto
author_rank: Contributor
timestamp: July 11, 2016, 09:34:10 pm
content: OLED, the only way to go!

author: Brumby
author_rank: Unknown
timestamp: July 12, 2016, 02:48:53 am
content: Great indoors. They are 'challenged' in daylight.

author: Fungus
author_rank: Super Contributor
timestamp: July 12, 2016, 10:25:19 am
content: Quote from: Porto on July 11, 2016, 09:34:10 pmIn a dark room, sure...(...and if you don't mind changing the batteries every few days)

author: Howardlong
author_rank: Super Contributor
timestamp: July 14, 2016, 10:42:39 am
content: Quote from: Fungus on July 12, 2016, 10:25:19 amSingle biggest reasonnotto go for OLED!

author: tungsten2k
author_rank: Newbie
timestamp: January 10, 2017, 08:51:16 pm
content: Great DaveCAD demonstration as always ! I remember enjoying this video when posted and am now revisiting due to investigation of similar problem I'm finding on nearly every LCD power control meter (e.g. Peacefair, etc) but having a tough time tracing it down. I want to stay away from led segment display due to light-sensitive environment these will be used in.For those who don't have the EEVBlog or Bryman meter to review, any pointer on thought process one would use determine how to find the contrast bias angle resistor if Bryman hadn't provided it ?Thanks for the video !

author: denisber
author_rank: Newbie
timestamp: April 30, 2019, 07:35:16 pm
content: Hi,I bought a DMM Yokogawa Ty720 and wanted to change the bias resistor too.How do find the bias resistor?Do they have some tips?I haven't a schematic or service manual.Thanks for any help!

author: arturmariojr
author_rank: Contributor
timestamp: September 21, 2022, 02:02:56 pm
content: Hi, DenisCould you improve the visibility of your Yokogawa meter?Best regardsArtur