Why do my UV sunglasses made a difference with the iPad?

Question

This is most bizarre. I tried using my iPad in my car today while waiting for a friend. I turned it on, and the screen stayed black (or so it appeared). I turned it off and on again. Nothing. I turned it sideways, and there was my desktop. I turned it vertical, and everything disappeared again. I took off my sunglasses, and it fixed the problem. I wear very high-end sunglasses with UV filtration (not polarized). I would understand if the screen blacked out in both positions. But with the sunglasses, it is black when held vertically and perfectly readable when held in landscape mode. It's not a huge problem. I just want to know why.
j

Answer 1

jeansheller wrote:
They had to make what choice? Isn't the screen the screen. What makes it different in one position from the other?
You can read about polarizers here: http://en.wikipedia.org/wiki/Polarizers
Also see: http://en.wikipedia.org/wiki/Lcd_display
When the polarizer in your glasses is parallel to the polarizer in the display, you see well. When they are at right angles, the light from the display is nearly extinguished. The polarizer in your glasses is set to darken the sky and reduce glare. The manufacturers of displays know which way your glasses are oriented in normal use and seek to match that orientation in their devices to maximize brightness. If you turn the device 90 degrees from normal, you have thwarted their attempts. If your device has two normal orientations..., well, that's the problem you are encountering.
Jerry
Message was edited by: Jerrold Green1