Crafting A Liquid Crystal Display

Throughout the 1960s, the management at RCA thought LCD displays were too difficult to commercialize and sent their engineers and researchers involved in LCDs off into the hinterlands. After watching [Ben Krasnow]’s efforts to build a liquid crystal display, we can easily see why the suits thought what they did. It’s an amazing engineering feat.

Before building his own version of an LCD (seen above in action), he goes through the mechanics of how LCDs operate. Light enters the display, goes through a polarizer, and is twisted by a liquid crystal material. The first successful LCDs used two types of liquid crystals – chiral and nematic. By combining these two types of molecules in the right proportion, the display can ‘twist’ the polarized light exactly 90 degrees so it is blocked by the second piece of polarizing film in the display.

Besides getting the right crystals and engineering processes, another major hurdle for the development of LCDs displays is transparent electrically conductive traces. [Ben], along with every other LCD manufacturer, uses a thin layer of indium tin oxide, or ITO. By embedding these clear electrodes in the display, segments can be built up, like the seven segment displays of a calculator or a bunch of tiny dots as found in a TV or computer monitor.

In the end, [Ben] was able to build an extremely simple single-segment LCD display out of a pair of microscope slides. It does modulate light, just barely. With a lot of work it could be made in to a calculator type display but for now it’s an awesome demonstration of how LCDs actually work.

17 thoughts on “Crafting A Liquid Crystal Display

      1. It could stand for Liquid Crystal Digital in some contexts, but it never does.

        Oh, and the first “LCD” in the article should be “LCDs”. At least he never put an apostrophe in there.

  1. ISTR Tim Hunkin doing this on The Secret Life Of Machines back in the day, he had two bits of glass in a clamp and dropped some liquid on the edge, allowing it to “wick” between them (or so it looked), and achieved a pretty passable LCD effect, albeit one big pixel.

  2. So, where would i, as a mortal, buy some of that fancy liquid crystal stuff?
    I looked at that some time ago but was unable to find any.
    There are a lot of failing LCD’s in older cars (like temperature displays or stop watches) and replacements are hard to find and/or cost a fortune.
    I ripped one apart and i think the glass plates are still usable. I just need the filling. :D

  3. Okay, obviously I’m not entirely too well versed in this, but what the hell is the GIF supposed to be that I’m not seeing? The GIF kinda seems to be pointless, it’s not showing much change, and the article is talking about polarization, but the colors change in only one area? wat?

    1. This will not work. You ask this question in the comments – a place that is only visited by readers who are interested in writing and/or reading comment. But this is not representative for all HAD readers. But I would vote for YES if following conditions are taken care of: Never should a gif have less than 5 Frames and the GIF-Effect should become present while the mouse is hovering over the Article-Image.

      As I said before: GIFs are great for explaining a lot about a project in a few frames. For exmaple the Keyboard that stud up when you get near it. That post had a strange title and like my description given in the last sentence, a gif showing how it just bumps itself up with a servo was quite self explaining. I like skimming thru the front page and only read the articles that might suport an Idea of me or has a possible solution to a likewise problem I’m currently chewing on. And the faster I understand what a post is about, I can skip it or sunk into it.

      If you dont want GIFs, I’m fine with that. But please elaborate your point or think about what you are blocking for others, just because you dont like it. As I mentioned above: A Mouse over would do the trick. You can have a disanimated website like you are used to since the start of the internet, and I can enjoy a more direct access to an article and if it is of to skip or one to stay.

      btw: especially and LCD is a great example for the use of a GIF. It has two states by nature and a single-stillstanding-image is not capable of explaining it very well. A GIF is IMHO ideal for explaining when it comes to objects with sequential behavior.

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