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How do Barcode Scanners Work? (2024 Update)

2.5 Minutes

In this article we will give a broad overview of exactly how a barcode scanner works and then apply it to a real life example to better illustrate how they work.

How Barcode Scanners Work

1. The Barcode and the Scanner:

Barcodes are unique patterns of black bars and white spaces that encode information, typically numbers or characters. These barcodes are printed on products or labels. A barcode scanner's main job is to read these patterns and translate them into a digital format that can be understood and processed by computer systems.

2. Rapid Reflection:

At the heart of most barcode scanners is a rotating mirror that propels a laser beam at high speeds. This laser scans across the barcode, rapidly moving back and forth.

3. Interacting with the Barcode:

As the laser interacts with the barcode, it is reflected off the white spaces and is absorbed by the black bars. This interaction with the bars and spaces produces a unique pattern of light reflections.

4. Decoding the Barcode:

A sensor inside the scanner, usually a photodiode, picks up the pattern of reflections. When the laser encounters a white space, more light is reflected, causing a peak in the electrical signal. A black bar results in less reflected light, creating a trough in the signal. The scanner then processes this pattern, translating it into a digital format that represents the information encoded in the barcode.

5. From Code to Product:

Once the barcode is read and decoded, it is translated into a unique identifier, typically a string of numbers. This string acts like a digital fingerprint for the product, linking it to a specific item in a database.

6. Price Lookup and System Communication:

The decoded number is sent to a computer system, like a Point of Sale (POS) system in a retail store. This system has a database that recognizes the decoded number, retrieves the product's details, and displays its price and other information for the cashier and customer.

7. Feedback Mechanism:

To confirm a successful scan, the scanner provides feedback. This might be in the form of a beep, a visual signal like a flashing LED, or even tactile feedback like a vibration.

Real-World Example of How a Barcode Scanner Works:

Imagine you're at your local grocery store in the checkout line. You've got a carton of milk in your basket, and it's time to scan it. Here's how the process unfolds:

1. The Barcode and the Scanner:

You place the carton of milk on the conveyor belt, revealing its barcode label. The cashier then slides it across the scanner's glass surface.

2. Rapid Reflection:

Inside the scanner, a swiftly rotating mirror reflects a laser beam across the barcode on the milk carton.

3. Interacting with the Barcode:

The laser beam dances over the barcode. When it encounters the white spaces, the light is reflected more, creating peaks in the electrical signal. On the black bars, less light is reflected, causing troughs in the signal.

4. Decoding the Barcode:

For the sake of our example, let's say the barcode on the milk carton encodes the number "123456789012". As the laser reads this barcode, it produces a signal pattern of:

1, 2, 1, 2, 1, 2, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 2, 1, 2, 2

(where each number represents the width of each bar or space on the barcode)

5. From Code to Product:

The scanner translates this pattern into the number string "123456789012". This number is the product's unique identifier. The store's computer system instantly recognizes this number and knows it corresponds to a carton of milk.

6. Price Lookup:

The system checks the database and identifies the price for the carton of milk, say $2.50.

7. Completing the Process:

The milk's name, price, and any other relevant information are swiftly sent to the cash register, where it's added to your total bill. In mere moments, the carton of milk has been identified and priced, all thanks to the marvels of barcode scanning technology!

We hope you now have a better understanding of how a barcode scanner works!

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