The summer season means more time spent outdoors or in the car (not driving!) with the iPad. If you’re wearing sunglasses, you may notice the iPad screen gets dim or even black. If you experience what appears to be a black or blank screen while wearing sunglasses, try this simple fix. Rotate the iPad 90 degrees. That is, go from portrait to landscape or vice-versa.
The reason your iPad screen appears blank is because most sunglasses are polarized. The lenses block light polarized in one direction or plane and your iPad screen is polarized in another plane. The effect can be that the image from your iPad screen is dimmed or blanked out.