use the computer to tint your windows?

**wizardPC** · 08-26-2000, 09:08 PM

Okay, when i was little i used to take things apart (didnt we all?) and I remember once i took apart a crude electronic game that had an LCD. When I got the screen apart I seem to remember that there were two peices of polarized plastic that were almost as clear as glass.

I am somewhat aware how text and graphical LCD screens work: basically you apply voltage and the pixel goes black. If any of you have a good graphing calculator then you have noticed that when the batteries begin to get low and the screen begins to fade you can crank up the voltage going to the screen and the characters are again readable (the pixels turn dark again)

You probably know where I'm going with this by now.

I want to use some of this LCD film to control the tint in my car. I figure that using a computer to control the necessary voltage I can use a slide bar to tint this film anywhere from 100% VLT (Visual Light Transmission)--transparent--to 0% VLT--opaque. The point would be so that I could have dark tint during bright sunlight and no tint during night/rainy conditions. The point of having opaque tint would be more of a security issue so that no one could see the thousands of dollars worth of equipment in my vehicle--out of sight, out of mind (if you dont know its there you wont want to steal it).

I was wondering a few things:
1. is it possible to apply enough current/voltage using a car battery to darken a "pixel" the size of a large car window?
2. Does anyone know where I can get some of this film with the liquid crystal pixels?
3. Is this gonna be more trouble than its worth?

Let me know what you think. Mr. Cake, your input is especially appreciated because if anyone knows anything about jerry-rigging electronics its you.

**snakebite** · 08-27-2000, 09:42 AM

Definatly possible but you tinting would be worth more than the car. Automatic welding lenses work using LC glass, when the light from the arc is sensed the lens automaticly blacks out.

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http://mp3gt.mp3car.com/

**mp3tbird** · 08-29-2000, 04:35 PM

LC requires an AC signal by the way -- just hooking up a battery is not a good thing to do, but they take almost no power at all to run. LCD driver chips have the circuity built-in to convert DC to the AC signal.

There have been home windows made that change opacity. Clear to a whitish frosted look via a controller mounted next to the window. Exceptionally expensive. I don't know if has made it into volume poduction yet, or if it is still experimental.

LC has lots of problems though:
- pressure sensitive (ever press on a LCD and see the rainbow colors?)
- temperature sensitive!!!
- I'm not sure about the optical quality of a flexible film on the windows -- might be hard to see thru. (tinting the front window when parked for security!)
- It is not something that you want to have leak all over the place if the window or film is damaged.

Don't get me wrong though -- it's a very cool idea. Perhaps an internet search will help find a manufacturer of LC film.

--mp3tbird

**GrendelT** · 08-30-2000, 12:14 AM

What the heck?! That would def. be the sweetest and weirdest thing i'd every seen a techie do to his car. Go with it tho, and send me a video when you get it done!

**wizardPC** · 08-30-2000, 12:44 AM

actually, after talking with several people, its been made very clear that currently it would be way too expensive. hell, im in the society of automotive engineers. maybe when i get into the workforce i can use the Big Three's money to put this in a concept car......

**koz** · 09-04-2000, 12:08 PM

Look up "3M Privacy Film" on Google. It's already been created. You apply a voltage to the film and it goes from opaque to clear.
http://www.manufacturing.net/magazin...97/05d8965.htm

[This message has been edited by koz (edited 09-04-2000).]

**wizardPC** · 09-05-2000, 05:16 PM

koz:
that stuff is kinda neat, but its not what i was looking for. As I understood it, that glass turns white, not black. And its not variable--its either opaque or transparent and nowhere in-between.

**Saab** · 09-05-2000, 09:17 PM

Actually, I think that it is variable because they talk about putting different voltages into it.
BEN

**koz** · 09-07-2000, 09:00 AM

I've played with a sample piece of the material direct from 3M, and it looks just like a tinted window when the current is off. It doesn't turn write, it turns dark. Just like a tinted window. And yes, varying the voltage creates a semi-linear response on opacity. Would have made a nice license plate holder... =)