iPad display dimmed when overeheated
I just had this issue with my iPad after using it in direct sunlight. As I was working, I thought the screen became harder to view in direct sunlight, but I rationalized it by thinking that maybe the noon sun was especially bright or my eyes were being strained, or something of the sort. Then, the iPad gave me the famed "too hot" notification with the yellow triangle, and shut down on me. So, I went inside, and gave it a minute or two to cool down. It quickly came back on, but the display seemed a lot dimmer than usual. I even put it alongside my iPhone 4 to test it, and sure enough it was very dim, even after toggling the auto-dim feature, and sliding the brightness to maximum. I did a hard restart, and that didn't fix it.
Lo and behold, after 3 or 4 minutes of messing with it, the iPad screen just popped back up to full brightness, and I hadn't done a thing.
I guess it's a way to safeguard against harmful internal temperatures that could damage the battery or circuitry?
I'm just glad that it wasn't permanent!