Here's how it would work: Every item would have a smart tag on it that indicates what it is. It can also hold data. Before you go shopping, you must get an account that is linked to your personal shopping card. When you go shopping, you first scan your personal shopping card to the scanner on your shopping cart. Then, you scan each item into the same scanner and put in in the cart. The cart's computer keeps a running tally of your balance. Then you simply roll your cart out the door, and the door scanner picks up that balance from your cart along with your account number and sends it to the main computer which then makes a debit to your account. Your account is linked to a credit card or a bank account or whatever. What if you change your mind? No problem. Simply take it out of your cart and scan it in a different scanner or throw a switch to indicate that it is a reversal. If you try to roll out of a store with an item in your cart on on your person that wasn't properly scanned, the cart's wheels will lock, and perhaps a red light could go on.
-- ProblemSolver, Mar 30 2006

This is baked. I've read about it, but can't find it.
-- miggavin, Mar 30 2006



random, halfbakery