How Do Barcode Scanners Work?

how does a barcode scanner work

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Barcode scanners have become an indispensable tool in today’s digital world. These devices are designed to scan barcodes and turn them into digital code that can be read and processed by a computer. 

But how do barcodes scanners work? In this blog post, we’ll look in-depth at barcode scanners, how they function, and their different types. We will also take a look at some common issues with barcode scanners. 

Before we dive into the working of barcode scanners, let’s first understand the basic of a barcode and a barcode scanner. 

What is a Barcode?

Barcodes are machine-readable codes used to store information about products. They are made up of a series of black and white vertical lines of varying width and spaces in between.

Refer to our article on what is barcode to learn in detail about barcodes, their working, different types, benefits, and more.

Two points explaining what are barcodes

What Are Barcode Scanners?

What do you mean by barcode scanners

Barcode scanners are devices that are used to read and interpret barcodes. 

A barcode scanner emits a light beam that is reflected off the barcode. This beam is captured and then decoded by the scanner to retrieve information in the barcode. 

Check out our article on types of barcode scanners to know more about the different types of barcode scanners available in the market today. 

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Components of a Barcode Scanner

A barcode scanner typically consists of four main components that enable its functioning. These are a light source, sensor, lenses and mirrors, and decoder. 

Depending on the model and its intended purpose, some barcode scanners may also feature additional components such as a display or wireless connectivity modules. To keep things simple, we will just explain the essential parts of a barcode reader and skip the other optional parts.

Two points about functions of Light source in a barcode scanner

Light Source

Barcode scanners need a light source to read a barcode. This light source is produced using a laser diode or LED. The light source illuminates the barcode, allowing the scanner to read it.

A laser diode source produces narrow, highly concentrated laser beams. Laser diode barcode scanners help read barcodes from a distance and are commonly used in warehouses, logistics, and other industrial settings.

A LED source produces wide beams of light that have a short range. LED source barcode scanners are helpful for close-range scanning applications and are often used in retail stores, supermarkets, and other environments where barcodes are placed close to the scanner.

Light Sensor

A sensor is a component that converts light signals into electrical signals. 

When the reflected light from the barcode reaches the scanner, the sensor is responsible for converting them into an electrical signal. 

There are two main types of sensors used in barcode scanners: Photodiodes and CCDs (charge-coupled devices).

A photodiode is a device that generates electric current when exposed to light. 

Charge-coupled devices contain an array of sensors that work together as a unit.

The primary distinction between a CCD reader and a photodiode (pen or laser scanner) is that the CCD reader works by measuring emitted ambient light by the barcode. In contrast, the photodiode measure reflected light of a specific frequency originating from the scanner itself.

Function and types of Light sensors
Two points about lenses and mirrors of the barcode scanner

Lenses And Mirrors

Lenses and mirrors are vital components of barcode scanners. They are responsible for multiplying and directing the reflected light beams to the sensor. They also help in capturing the reflected light from the barcode efficiently.


A decoder is a device that interprets electrical signals from a sensor and converts them into readable information such as alphabets and numerical values. A decoder extracts data from a barcode by analyzing the electrical signals sent by the sensor.

Features of a Decoder

What is a Scan Engine?

Scan Engine is a term used to refer to the combination of the light source, sensor, decoder, lens, and mirrors. They work together to interpret barcode information and convert it into data that can be used for further processing.

Scan engines are available as a single unit in the market and can be used to add barcode reading capabilities to devices.

Check out our article on what is a barcode scan engine to learn more. 

How Does a Barcode Scanner Work?

Five points explaining how barcode scanners work

Now that you know the components of a barcode scanner, let’s understand the steps involved in barcode scanning.


The barcode scanner is placed in an appropriate position to read the barcode.

The placement of a barcode scanner depends on its type. 

If a contact scanner is being used, then the product with the barcode should be placed in front of the scan window of the scanner. 

If a non-contact scanner is being used, the barcode scanner should be aimed at the position of the barcode that has to be scanned.


When the scan button on the scanner is triggered, the light source gets electrically charged and emits light. This light is directed toward the barcode to illuminate the barcode area.


When the light is directed toward the barcode area, some of it is absorbed by the barcode, and some part is reflected back toward the barcode scanner.

In a barcode, the dark bars absorb the most light, whereas the white part reflects the most light. This difference in absorption and reflection is what allows barcode scanners to read the barcode.


The reflected light is now received by the sensors. These photosensitive devices now decode the light based on the light intensity received and identify the details embedded in the barcode. 

Once the data has been detected, an electrical signal for the matching data is generated. The sensors translate the data into binary form (a string of 0 and 1). 

Decoding and Output

The electric signal is sent to the host device, which is then decoded and presented on the screens. Decoding can also be done by using software designed for the scanner.  

Types of Barcode Scanners

There are many different types of barcode scanners on the market, each with unique features catered to particular industries and business requirements. We have a dedicated guide on different types of barcode scanners in which we have categories scanning device on the following basis.  

  • Contact and non-contact
  • Build quality
  • Type of bar code scanned
  • Form factor
  • Connectivity option 
  • Scanning technology 

Common Issues With Barcode Scanners

List of five point about issues with scanners

Though barcode scanning is highly efficient, a few issues are commonly seen while using them.

Connectivity Issues

Issues may arise if the scanner is not properly connected to the computer. Wireless scanners can have issues with connectivity at low battery percentages. Due to hardware issues, most old models cannot be connected to new computers.

Compatibility Issues

Barcode scanners cannot read all types of barcodes. Some barcodes require specific types of scanners to read them. Some barcode readers also have a minimum input criterion to read barcodes. Trying to read a barcode with a non-compatible scanner will cause compatibility issues. 

Refer to our article on can barcode scanners read all barcodes for a more comprehensive view. 

User Error

User error is the most common error associated with barcode scanners. 

The scanner should be placed at the correct angle at apt distances for it to read the barcodes. Objects can block the line of sight between the scanner and the barcode leading to errors as well.

Issues With Light Beam

Glare from nearby light sources can mess with light beams projected by barcode scanners. Reflective materials nearby can also cause the laser beam to undergo reflections resulting in barcode reading errors. Poor alignment between the barcode and the scanner can also lead to errors.

Programming Issues

If the software used to interact with the scanners has errors and/or is not up to date, it can cause problems. This can lead to scanners malfunctioning and or resulting in data errors.

Frequently Asked Questions

How Does a Barcode Scanner Communicate?

A barcode scanner communicates with a barcode by using a light beam. The light beam projected at the barcode is reflected back into the scanner. The scanner then measures the intensity of light reflected back from the barcode using light sensors to decode the information.

How do Scanners Cope Up With Moving Objects?

Moving objects present a challenge for scanners and cameras, as the barcode image they capture can be distorted. To combat this issue, computer algorithms are employed to turn blurred patterns into clear barcodes. This allows scanners and cameras to capture the necessary data while enhancing their capacity accurately.

Do Barcode Scanners Read the Black or White Bars?

Barcode scanners do not actually read black or white bars. Scanners project a light beam at the barcode. Black stripes absorb the light reflecting less light compared to the white space. The scanner analyses the reflected light to decode the information in barcodes.

Can a Barcode Scanner Read Text?

No. Barcodes are not optical character readers. They can only analyse barcodes with the help of light beams.


In conclusion, modern barcode scanners are powerful tools that help businesses track and manage data efficiently. By using different types of scanners and symbologies, industries can customise their barcode systems to fit their needs. 

From retail to healthcare, barcodes and barcode scanners are ubiquitous in the modern world, and understanding how they work is an essential part of being a competent user. By using them correctly, a right barcode scanner can help streamline processes, reduce errors, and improve efficiency across a wide range of applications.

We hope this blog covered all the information you needed about how does a barcode reader work and gave some insight into the world of barcode technology. 

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