How Do Barcode Scanners Work?

By: John Barth

So you want to know how barcode scanners work. Well, we first want to narrow down which type of barcode scanner we are talking about. There are many types of barcode scanners from laser scanners, CCD barcode scanners, imager type scanners, and more. Our first focus will be on how a CCD barcode scanner works.

The CCD barcode scanner is a scanner that has no moving parts. CCD stands for Charged-Coupled Devise Scanner. The scanner has a light source that when pointed to an object or barcode, it illuminates that image. The image is usually a barcode. Once the barcode is illuminated, a reflection is created and the barcode scanner reads that image.

How does the barcode scanner read the image? Well, there is a linear photodiode within the scanner head. This photodiode can read the reflected light off the lines on the barcode. This reflection is a digital image that is then scanned electronically within the devise. When the image is scanned electronically, each bar on the barcode is converted to the corresponding number or letter.

The barcode scanner is connected to a PC or Mac and the CCD scanner then sends the sequence of numbers and/or letters to the PC or Mac to populate the field of entry. This connection can be made in a number of ways. On way is with a keyboard wedge. This is a Y connection where one end of the Y connects to the keyboard and the other end of the Y connects to the scanner with the bottom of the Y plugging into the PC where the keyboard would normally connect. This method is used many times when the PC does not have enough interfaces. Serial is another connection method and works with just a straight serial cable from the barcode scanner directly to the PC serial connection. USB is now about the most popular method, because most PC's and Mac's today have many USB ports. Just plug and play!

Now we can look at how a laser barcode scanner works. The laser scanner works by sending a low energy light beam or laser beam to read the spacing between a pattern on the image one space at a time. The beam is moving back and forth by using a mobile mirror which causes a blinking effect. You can usually see the read line moving over the barcode. The reflection comes back and is then read by the fixed mirror in the scanner. The scanner then generates analog and digital signals that match the pattern. A barcode reader decoder then processes the information and sends it through the data communications interface.

Wala! Knowing how a barcode scanner works answers a lot of questions about where you can use a barcode scanner. They are becoming so popular now, you can find them everywhere in retail stores scanning items.

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