Science/technology question
So, in my truck I got one of those mirrors that automatically gets a few shades darker whenever your dumb ass forgets to dim the brights when you come up on my tail. However, I noticed yesterday it didn’t work when the Sun was blazing away behind me on the drive. Anyone know how these things work?
Just curious.
Update: That was fast. Answer in comments.
January 4th, 2008 at 10:40 am
They have a light sensor on the front and rear of the unit. When the sensors read a brighter from behind than the front they darken. Mine also does not work when it is light out.
K
January 4th, 2008 at 10:43 am
Ah, that explains the mechanics. So, how does the mirror actually get darker?
January 4th, 2008 at 10:45 am
Liquid crystal. Apply a little juice, the polarization changes and light can’t go through it as well.
January 4th, 2008 at 12:12 pm
Mine also does not work when the sun is hitting it, only car lights. This is slightly annoying because on my “old school” mirror, I could flip it up if the sun was hitting it.
January 4th, 2008 at 12:16 pm
Sometimes, manual is better.
January 4th, 2008 at 12:19 pm
Rust, tell me about it. I still have to roll my windows up and down.
January 4th, 2008 at 12:54 pm
I don’t even have windows on mine…
January 4th, 2008 at 6:01 pm
My glasses darken when it’s bright — except in the car.
January 4th, 2008 at 6:17 pm
“I still have to roll my windows up and down.”
Mine are electric. Have you ever thought about having to escape from a vehicle in which the electric windows have failed for some reason? (Like, I dunno; an underwater emergency or something.)
I have. I’m not crazy about it at all.
January 4th, 2008 at 8:25 pm
Recently bought a similar (Ford Taurus) mirror on Ebay and installed it in my 10 year-old Camry. Easy… it slide over the existing mount, and I connected it to 12V & Ground at the sunroof.
The integral compass is GREAT, but the mirror didn’t dim enough with bright lights behind in dusk/dawn conditions. So I gave the front photocell a swipe with a broadtip black permanent marker so the mirror thinks it’s darker outside. Now I get better low-light dimming, and its still perfectly clear in daylight conditions.
January 4th, 2008 at 10:59 pm
“My glasses darken when it’s bright — except in the car.”
I hear it’s because the windshield is UV shielded.
January 5th, 2008 at 12:39 am
Electric or not, you ought to have a window punch within reach of the driver’s seat. Even if it’s not an underwater emergency, your window can become stuck shut in a crash from which you need to escape.
January 5th, 2008 at 2:22 pm
Top Gear did a test a few years ago by putting a car into a water tank, and they found that the whole thing of “wait in the car until the pressure equalizes” is crap. Get out as fast as possible. In the test, when waiting for the pressure to equalize, the presenter would’ve drowned if he hadn’t had a diver with him. When he opened the door the second the car hit the water, he was able to get out just fine.