EEVblog #1044 - LCD Technology Tutorial

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 AN658

Support the EEVblog through Patreon!

Donate With Bitcoin & Other Crypto Currencies!

EEVblog Amazon Store (Dave gets a cut):

[MicraHakkinen]

5:38 Funny case in fact about LCD's being sluggish when cold, my mom's car has an LCD displaying (among other info) the outside temperature. When it gets near or below freezing, the temperature indication will blink to alert you to that. Except that precisely because it is cold, the blinking will be almost unnoticeable since the indicator hardly fades before it comes back on again.

[Stevedot]

This is exactly what I expect from your channel. A way to learn electronics, combined with your experience, not seen in any other channel. A bit of stuff for the beginner, a bit of new stuff for the experiences. Great subject!

[piast]

Well, you actually can drive a simple LCD display with common microcontroller GPIO if you need. Just drive the common electrode and inactive segments low while driving active segments high for 100 ms then switch everything by inverting the output: high on common and inactive and low on active segments for another 100 ms. That way you generate AC square waveform with no DC component relative to the common LCD electrode.

[ChristianKoehler]

I sometimes used "simple" LCDs directly connected to a micro. You can do that without burning out the display by generating the AC in software. Connect both the common and the segments to GPIOs. Set the common to high and the segment to low and reverse that every 1/100s using an interrupt. To turn off a segment set its GPIO to the same logic level as the common (so no voltage across that segment, even if both the common and the segment change level every 1/100s). With clever programming you can even drive multi common displays this way.

[stevef]

I still find it absolutely amazing that LCDs are in everything from cheap calculators to 100" 4K Dolby Vision enabled TVs. You don't get that kind of scaling from any other display technology.

[Lampoonlongtails]

Another presentation (style and content), many will want to emulate. Dave Jones, the educator!
Cheers.

[meepk]

I was looking for the second video, then I realized it was published yesterday! I'm finally caught up. I thought this day would never come.

[QLTD]

very useful tutorial, thanks Dave, looking forward to the next part :)

[ChipGuy]

This big single digit LCD (or a similar one) was used in a clock circuit published in one of these electronic paper magazines. I think it was elektor. It was 10+ years ago. Point is: Since they are static they just used 74HC595 or 4094 (can't remember exactly) to drive all the segments. The common pins were tied together and driven by something else. The microcontroller had to do the AC switching of course. The display is so big that it was no problem to hide the DIL ICs underneath it.

[anrb]

It's actually possible to drive the through-hole type (the simplest) LCDs using GPIO output pins by reversing the drive polarity in a loop (I used a 4Hz timer). I used a TI MSP430F2272 micro-controller that had all the required GPIOs.

[eldstgilmorbarboydodellatb]

💚💚💚💚 bookmark/ notes: 11:14 strip / eraser pressure for the changing lcd …..ect……tbc….-g-b, bot

[pinolec]

Thanks Dave. Looking forward to next video in the series. Very interesting topic.

[theNeWo]

I've always wanted to know how to get custom lcd displays made. Looking forward to the other videos!

[keyen]

Dave, a tutorial on the multiplexing biasing would be great.

[Coyote]

Very useful video, it helps a lot. So easy to understand even for non Aussie listeners.

[andrewkowalczyk]

Excellent video, just in-depth enough to explain the differences, looking forward to the rest of the series

[dgo]

19:02 isn't the blue one(@ 10:38) transmissive?
at least I thought that since the ones like that "blue backlight lcd 16x2 whatever" seem to be unusable unless you use the backlight

[danieltille]

Thanks a lot for your video about displays. I am just disappointed that most displays used in DIY projects are simple few segments LCD or up to 640x480 displays. I would however like to use smartphone displays having much higher resolutions for displaying good quality images. those displays are mainly driven by the MIPI standard. I am still looking in ways to interface those displays with simple microcontrollers and by using an intermediate graphic driver having a frame buffer. The microcontroller would just fill the frame buffer (for picture display, low refreshment would be ok) and the graphic driver would control the "smartphone" quality display accordingly. Maybe this could be an interesting subject for a future video.

[sprybug]

Yes! I've been waiting for this series. I've been wanting to experiment with LCDs for a while, plus I got a Raspberry Pi Zero (and RPZW) coming in the mail. Can't wait!

[ceneblock]

You tease! You get me excited for designing a LCD and now I have to wait.

:(