Different types of barcode scanners are available for all kinds of applications. In small, convenience stores, you’ll typically find a basic wand scanner. The simplest ones look like electronic pens or giant, oversized razors. They shine red LED light onto the black and white barcode pattern and then read the pattern of reflected light with a light-sensitive CCD or a string of photoelectric cells. If you have a pen scanner, you have to run it across the barcode so it can reach each block of black or white in turn; with a wand scanner, the CCD or photocells read the entire code at once.
In a busy superstore, you’re more likely to see a very sophisticated laser scanner. It’ll be built into the base of the checkout lane, under a piece of glass, and you may be able to see the laser beam being bounced around at high-speed by a spinning wheel so it reads products (literally) in a flash. Another technology uses a small video camera to take an instantdigital photograph of the barcode. A computer then analyzes the photograph, picking out only the barcode part of it and converting the pattern of black and white bars into a number. (Barcode-scanning apps that run on cellphones work this way, using the phone’s built-in camera to photograph the code.) Scanners like this can accurately read dozens of products waved past them each minute and are far more accurate than old-style checkouts (where you have to key in the price of every item by hand). The best barcode scanners are so accurate that they make only one mistake in something like 70 million pieces of scanned information! (Compare that to typing on a keypad, where you’re typically likely to make one error in every 100 characters you type.)
Barcode scanning technology has been around since the early 1970s but only really caught on in the 1980s and 1990s after stores started to invest in sophisticated, computerizedelectronic point-of-sale (EPOS) checkout terminals. Back then, store checkouts cost many thousands of dollars. Today, scanners are much more affordable. You can buy a simple,USB barcode scanner and software and hook it up to an ordinary laptop or computer for just a few dollars. Thanks to barcodes, even tiny convenience stores can run as smoothly as Wal-Mart these days!