MacRumors reports that some of Apple’s older Smart Covers, as well as certain covers offered by third-party accessory makers, are not working properly with the new iPad. According to the report, the problem arises because of changes in the way the new iPad’s magnets function…
“The new iPad has a slight change in how its magnets work. Apple has reversed the polarity of one set of magnets related to the sleep/wake sensor that turns the iPad off when the Smart Cover is closed. As a result, older Smart Covers, that weren’t designed with this change in mind, fail to turn the new iPad off when they’re closed.”
Mark Booth shed some light on why Apple made these changes:
“I’ve learned why Apple decided to use a polarity sensitive switch in the new iPad 3. Some iPad 2 customers were having issues with their iPads entering sleep mode when they flipped Apple’s Smart Cover around flat behind their iPad 2. Since the iPad 2′s sleep/wake sensor wasn’t polarity specific, it could sometimes be triggered from the magnet being positioned at the rear of the iPad. By changing to a sensor that requires the correct polarity, the problem is eliminated.”
According to Booth, Apple has been honoring customer requests to have their old Smart Covers replaced with the newer revision. If you have a third-party Smart Cover, try contacting the manufacturer to see if there a solution available.