EEVblog #1044 - LCD Technology Tutorial - Page 1
Forum section: electronics / general

author: EEVblog
author_rank: Unknown
timestamp: December 02, 2017, 12:20:57 am
content: Part 1 in a series of videos on designing a custom LCD display.This tutorial covers how LCD displays work, the 3 different types of interface (DIP, Elastomeric, Flex), the three different optical types (Reflective, Transflective, and Transmissive), and the two different types of drive (Static vs Dynamic)Microchip AN658http://ww1.microchip.com/downloads/en/AppNotes/00000658B.pdf

author: floobydust
author_rank: Super Contributor
timestamp: December 02, 2017, 12:56:25 am
content: Link "video unavailable"fixedPlease include low temperature fluids, use them here in the Great White North down to -30C. Needs more drive though, +/-5V and contrast moves around lots with temperature.

author: tautech
author_rank: Super Contributor
timestamp: December 02, 2017, 01:35:40 am
content: Looking forward to the future vids, excellent topic.

author: W2NAP
author_rank: Unknown
timestamp: December 02, 2017, 01:35:48 am
content: hmmm "This video is unavailable."something is broken.

author: rs20
author_rank: Super Contributor
timestamp: December 02, 2017, 01:55:32 am
content: I think he's correcting a couple of issues; which is awesome -- trading in short-term view stats in order to ensure that he has an awesome, accurate video in perpetuity.

author: EEVblog
author_rank: Unknown
timestamp: December 02, 2017, 02:31:43 am
content: New upload link working again.

author: SeanB
author_rank: Super Contributor
timestamp: December 02, 2017, 04:14:32 am
content: Quote from: wilfred on December 02, 2017, 02:59:55 amHe does mention a few times the next one about LCD will cover that.

author: unclebob
author_rank: Contributor
timestamp: December 02, 2017, 12:42:34 pm
content: Really great tutorial, I can't wait to see the other parts. Thanks a lot.

author: EEVblog
author_rank: Unknown
timestamp: December 02, 2017, 12:55:34 pm
content: Quote from: wilfred on December 02, 2017, 02:59:55 amI don't think that far ahead.

author: jonovid
author_rank: Super Contributor
timestamp: December 02, 2017, 02:55:29 pm
content: Thanks Dave.it's about time! looking forward to next video.what happened when posting the video to YouTube.some of us like to fiddle or mod LCD displays for fun.

author: Twoflower
author_rank: Frequent Contributor
timestamp: December 02, 2017, 05:33:35 pm
content: Very informative as usual.But the term "LCD Display" makes me shudder all the time. It's just not a Liquid Crystal Display Display. But as a non native English speaker I should be careful for what I call for

author: richnormand
author_rank: Unknown
timestamp: December 02, 2017, 06:24:14 pm
content: Nice video Dave. Looking forward to the next one.Suggestions for followup videos (in addition to added tutorials)Looking at:Driving schemes and pitfalls for directly addressed LCDs with standard chips.Are there standard pinouts/voltages to look for?Embedded/onboard hardware and software drivers with LCDs to look for (like the Noikia with ARM Cortex drivers combo (Github)Also of importance for many that have older equipment:Any way to increase the contrast of LCD panels on older HP, Ithaco, Pace, Canberra and the like. Typically they do not have contrast adjustments and are only readable using a strong light in front of the display now.Any way to regenerate the older LCD to work better, as many of these displays are OEM and not replacable.Options for adding back lighting to LCDs that did not have provision for that (like some of the retrofits shown on the EEVblog forum)Keep up the good work.Cheers and thanks.

author: Ertew
author_rank: Newbie
timestamp: December 02, 2017, 09:38:39 pm
content: Dave, can You include "silver polarizer" and frontlight in next videos?Transflective LCD have "black polarizer" on both sides and reflector on bottom. Light that doesn't pass are absorbed by polarizer. Silver polarizer (located at bottom of LCD instead of black polarizer and reflector) reflect light that doesn't pass through. In this construction active segments shows light from backlight unit while inactive segments shows light from environment. Results: poor contrast in poor light but excellent both in sunlight and darkness.Second nice technology are reflective display + frontlight unit. Technology was popular years ago when other types cannot give enough brightness. Photos below shows my ST5111 (reflective) and E52 (transflective). Both with light turned off.http://forum.bongofish.co.uk/index.php?topic=2561.0- here are my review of that ST5111 tablet-PC. Sadly all photos are gone.Quote from: richnormand on December 02, 2017, 06:24:14 pmBroken LCD cannot be fixed. But broken connectors (common problem) can be easy to fix by replacing zebra rubber or carbon flat flex cable. The most problematic damage are broken conductive tracks on LCD.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 03, 2017, 12:32:10 pm
content: I noticed a while back that ultra cheap items, like a 4 dollar multimeter and a calculator, often had very nice high contrast displays even when compared to very expensive multimeters. I wondered about that and I guess this video explains it. No backlight!

author: HKJ
author_rank: Super Contributor
timestamp: December 03, 2017, 08:36:17 pm
content: Quote from: Mr. Scram on December 03, 2017, 12:32:10 pmThere is also another explanation: Simple display. Simple multiplexing gives better contrast.

author: Peabody
author_rank: Super Contributor
timestamp: December 03, 2017, 09:42:23 pm
content: This discussion brings to mind the fact that the display on my Sharp Carousel microwave oven is getting dimmer with age. It appears this is a common problem on a lot of such ovens. Everything still works fine, but you just can't quite read the display anymore. An odd form of planned obsolescence.But on closer inspection, the segments are actually lit up, on a black background. Does that mean it's really an LED display, not LCD? Well, I guess the backlight could be amber. There is a bit of polarizer darkening, but not total like my laptop display. The Youtube videos on this problem refer to Sharp LCD display. So is it likely there is a fix - short of replacement?

author: EEVblog
author_rank: Unknown
timestamp: December 03, 2017, 10:20:32 pm
content: Quote from: Mr. Scram on December 03, 2017, 12:32:10 pmAll things being equal, less or no multiplexing = better contrast.More expensive meters typically have dual display, bargraph etc, that means a lot more segments, more commons, and more multiplexing required.

author: coppice
author_rank: Super Contributor
timestamp: December 03, 2017, 11:42:33 pm
content: Quote from: Peabody on December 03, 2017, 09:42:23 pmMost older microwave ovens, and even many new ones, use VFDs (Vacuum Flourescent Displays). Like any form of electron tube they do wear with age, and become dimmer. Their lives aren't too bad, though. If you've had the oven 10 years, and its one which displays the time all day long, the display has run for nearly 100k hours. That's not a bad life for a low cost electron gun device.

author: coppice
author_rank: Super Contributor
timestamp: December 03, 2017, 11:48:14 pm
content: Quote from: EEVblog on December 03, 2017, 10:20:32 pmHistory has been largely as you said. 1mux being higher contrast, wider viewing angle and wider temperature range that 2mux, with this pattern going up to 4mux. However, for displays beyond 160 segments (40x4) its getting common to use 6mux or 8mux. Many of these give really good contrast over a wide viewing angle and a reasonable temperature range while running from just 3 volts. To get most 4mux displays to work well over a wide temperature range you need nearer to 4 volts. I don't know what is different about the design of these higher mux panels.

author: Peabody
author_rank: Super Contributor
timestamp: December 04, 2017, 12:11:55 am
content: Quote from: coppice on December 03, 2017, 11:42:33 pmIt's a Sharp R-303CW, and I found the manual and schematic for it. It is an LCD display, and appears to have an LED backlight - four LED's in series with an 82-ohm resistor to ground, controlled by one PNP transistor.The display has 25 pins, composed of 22 SEG and 3 COM. There's a big ribbon connector, but I think if that was the problem there would be some segments dimmer than others, or completely dark. But mine is just uniformly dim. So, it's a mystery.Built in 2001. Hell, it's barely broken in.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 04, 2017, 01:17:26 am
content: Quote from: EEVblog on December 03, 2017, 10:20:32 pmIn this case it's a calculator with a graphic display, so I assume it does lots of multiplexing. Not too long ago this calculator would have been the duck's guts, now it's about as cheap as they come. In the case of the multimeter you're probably right, though!

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 04, 2017, 01:22:09 am
content: Quote from: Peabody on December 03, 2017, 09:42:23 pmAs a side note, I've noticed how people have shifted towards calling a lot of forms of wear or weaknesses in a design "planned obsolescence". In my mind there has to be a very intentional and deliberate act of shortening the lifespan of a product by the design choices made to call it that. Something that's run for over 15 years continuously and still works can, in my mind, not be called planned obsolescence by definition.

author: rs20
author_rank: Super Contributor
timestamp: December 04, 2017, 05:55:54 am
content: Quote from: Mr. Scram on December 04, 2017, 01:22:09 am+1. I think they're just trying to be "edgy" and "stick it to the man".

author: ggchab
author_rank: Frequent Contributor
timestamp: December 04, 2017, 12:04:58 pm
content: Very interesting tutorialThanks

author: Peabody
author_rank: Super Contributor
timestamp: December 04, 2017, 02:18:17 pm
content: Quote from: rs20 on December 04, 2017, 05:55:54 amOk, I'll admit to being unfair about that. It just seemed a shame that something still working perfectly would have to be replaced just because the display is getting too dim to see. I'm still curious about why it's dim. Segments that have been turned on only a few times in that 15 years are dim too, like the "defrost" indicator. Well I'll go back and view the episode again and see what might apply.

author: Mr. Scram
author_rank: Super Contributor
timestamp: December 04, 2017, 03:44:19 pm
content: Quote from: Peabody on December 04, 2017, 02:18:17 pmI think almost all devices end up being scrapped due to a few components costing a few cents. We generally don't repair any more, for better or worse.If it's a LED display and all the lights are dim, I think it might be an issue with the power supplied to the LEDs. Maybe it's a constant current source going bad.

author: Peabody
author_rank: Super Contributor
timestamp: December 05, 2017, 10:51:30 pm
content: Quote from: Mr. Scram on December 04, 2017, 03:44:19 pmI took the cover off intending to do some voltage measurements, but the board in question isn't readily accessible, plus (even in 2001) it's all the very smallest surface mount stuff. So unlikely I could either find the problem or fix it, or keep from messing up the glued-on ribbon cable to the display in the process. So I just put the cover back on.But now, when the door is closed and the oven isn't doing anything, the display is pretty bright! If I open the door, or start it cooking, it goes dim. As you say, looks like a power issue. So clearly I need to go back in and remake all the connectors. And that would include the fuse holders. Anything else? Anyway, I may very well owe Sharp an apology.

author: flowbee64
author_rank: Newbie
timestamp: December 29, 2017, 09:36:43 pm
content: Another great tutorial, Dave. I've really enjoy your videos and catching up on the technology that I never taught myself correctly. I find myself saying "huh! wow!" several times during each.And when I start watching one my wife hears the "Hoi!" opener and smiles.

author: Kris0725pl
author_rank: Newbie
timestamp: August 14, 2022, 09:49:09 pm
content: Hi all...i have two pcb module from epson printer. Model is here:290,04 zł 6%OFF | Kontroli montaż panelu dla HP M130nw M132snw M131 M133 M134 M227D M230d M230sdn M227sdn sterowania drukarki tablica na klucze G3Q74-60101https://a.aliexpress.com/_vLFIDLThis is 13 pin lcd control with stm8S003 microcotroler.Pin 1,2,8,12 and 13 is GND.I search any information how to use this lcd with Arduino or some info about pinout.Any help?