We all see numerous barcodes on a daily basis: at work, in a grocery store, or on parcels. But do you know how barcode scanners work? If not, we’re here to tell you everything you need to know.
In this guide, we’ll explain what barcodes are used for, what types of barcodes exist, and how they encode data. Plus, we’ll list the types of barcode scanners and answer some of the most common questions related to them.
- Why Use Barcodes?
- Types of Barcodes
- How Barcodes Encode and Represent Data
- Types of Barcode Scanners
- How do Barcode Scanners Decode Information?
- FAQ. Frequently Asked Questions About Scanners.
Why Use Barcodes?
Barcodes represent information in graphic form that can be accessed with a scanner. In other words, barcodes can store a lot of information in a compact image. This information can be uploaded into the company’s internal system to track the asset status.
Barcodes are widely used for product or shipment identification and can provide information about details such as origin, manufacturer, color, destination, etc. Often, barcodes can be found on boarding passes, documents, or ads. They are implemented in a wide range of industries, including manufacturing, warehousing, logistics, retail, healthcare, and delivery.
Types of Barcodes
To understand how barcodes encode information and how it’s decoded by scanners, we must first familiarize ourselves with the different barcode types. In this section, we’ll explain how barcodes differ and where they are most frequently used.
One-Dimensional Barcodes
One-dimensional barcodes are also called linear barcodes. You’re likely familiar with them from retail outlets, where they help to identify product names and prices at the checkout. Such barcodes represent data in a combination of varying width lines and spaces, often (but not mandatory) with characters underneath. Linear barcodes may have varied or fixed lengths depending on the type. Here is only a fraction of all linear barcodes used in the US:
UPC Code
UPC code stands for universal product code. They are typically used to label and scan products at checkouts. They represent data in the form of 12 digits, though some retail outlets use a smaller UPC-E version containing six digits. UPC codes also help to identify products for inventory management, providing information on color, name, manufacturer, and stock level.
Code 39
Code 39 barcodes are also used to identify products in different industries, but mainly in the automotive industry and by the US Department of Defense. The name indicates that this type of barcode can only encode 39 characters. Due to low data density, they can’t be used on small goods. The main benefit of this barcode type is versatility – it can be read by any barcode scanner.
Code 128
Code 128 barcodes are practically identical to code 39 barcodes, only they encode 128 characters. This barcode type is mostly used in supply chain operations due to its high data density.
Codabar
Codabar barcodes are the easiest to generate. They can be produced by any printer and are widely used in healthcare and logistics. This type of barcode encodes 16 special characters and four start or stop characters.
Two-Dimensional Barcodes
Two-dimensional barcodes are a newer barcode type than linear, representing data in unique patterns. The main advantage of two-dimensional barcodes is high data capacity and error tolerance. Even if a part of the barcode is damaged, it remains readable. However, these barcodes can’t be read by laser scanners. There are only four types of two-dimensional barcodes:
QR Code
QR codes are the most popular two-dimensional barcode type, applied in retail, entertainment, and advertising. Highly versatile, these barcodes can be printed in nearly any size and offer fast readability. QR codes are public domain, so anyone can generate such a barcode without an individual prefix.
Datamatrix Code
Datamatrix codes are even more versatile in size than QR codes and therefore are used to label the tiniest goods and documents. This barcode type is developed to be readable in low-resolution and low-light environments.
Aztec
Aztec codes look very similar to QR codes but can be recognized by a square in the center. They’re commonly implemented in the transportation industry, especially on tickets. They remain readable in low resolution and don’t require a surrounding blank zone.
PDF417
PDF417 codes are generally used by governmental structures for boarding passes and logistics. They have up to 1.1 kilobyte data capacity, higher than any other two-dimensional barcode type. Like QR codes, these are public domain and can be freely used by anyone.
How Barcodes Encode and Represent Data
Barcodes are used to identify assets and track their status, but how do barcode scanners work? The answer is encoding. In one-dimensional barcodes, data is contained in a series of varying widths and vertical spacing bars. When we look at a barcode, it’s hard to understand where one digit ends and the other one begins. But it’s really rather simple. Each character is given the same amount of horizontal space. In the case of UPC barcodes, it’s seven lines. Each digit is prescribed a unique black-and-white line combination that can be even read by a human.
Apart from the machine-readable part, most barcodes also contain a human-readable part underneath. This part can consist of digits, letters, or symbols in different combinations. A barcode scanner doesn’t read these characters but if it fails to read the lines, you can enter the unique code manually. The characters on their own can often tell you a lot about the product. In UPC barcodes, the first six digits indicate manufacture, and the last six indicate the product number.
Apart from the lines and characters, some barcodes also feature star and stop characters represented as special patterns. These patterns indicate to the scanner which barcode part it should read in the case of variable-length barcodes. Start and stop characters aren’t necessary for fixed character barcodes.
In two-dimensional barcodes, data is encoded in a unique pattern. Each type of two-dimensional barcode features a specific symbology language that indicates to the scanner how to read information.
To make things clearer, let’s provide an analogy with human languages. We can read a sentence in English, and a scanner with an installed QR-code dictionary can read a QR code. But if you try to read a sentence in Latin, you’ll likely understand the letters but not the meaning. The same goes for barcode scanners – without an installed QR-code dictionary, the scanner will not be able to decode data.
You may be wondering, aren’t the number combinations of linear barcodes limited? Indeed, although the possible combinations are sufficient for most businesses to mark all their products, they aren’t endless. That’s why businesses often have to reuse linear barcodes. Typically, this happens when one product is discontinued, and another replaces it. But sometimes, errors happen, and two products end up having the same barcode. Two-dimensional barcodes have a higher number of possible pattern combinations and therefore can be used in larger organizations.
Types of Barcode Scanners
Different barcodes require different barcode scanners. Let’s look at three scanner types and define their benefits and drawbacks.
Laser Scanners
Laser scanners are most common and are typically corded. They work by emitting a red diode laser reflecting the barcode for further decoding. Such scanners can only read one-dimensional barcodes and are therefore the cheapest. They’re fast, powerful, accurate, and capable of decoding hundreds of scans a second from a relatively large distance away. However, laser scanners may have difficulties capturing barcodes in high ambient light environments.
CCD Scanners
CCD stands for charged coupling device. These scanners are also called linear imagers. They decode barcodes by capturing the barcode as an image and processing characters. When the scan is triggered, CCD scanners produce a red focus line similar to that of laser scanners.
CCD scanners are more durable than laser scanners as they don’t have any moving parts. They’re also cheap and can read barcodes under direct sunlight or from device screens. The main drawback is barcode size and scanning distance limitations. CCD scanners can’t decode barcodes wider than the imager line or from over a couple of inches away.
Two-Dimensional Imager Scanners
Two-dimensional imager scanners are the most expensive yet the most versatile scanner type. They can decode any barcode type including two-dimensional and are extremely powerful. Such scanners can capture images on nearly any surface, even damaged, and from a large distance and at high speed.
Two-dimensional imager scanners are used in mobile computers such as the Honeywell Dolphin CT60. These devices combine the functionality of a proper working station and a barcode scanner in a compact body. Handheld computers enable your team to track inventory in real-time, communicate efficiently, and access data stored in the cloud, all from a single device.
How do Barcode Scanners Decode Information?
Finally, you can use the acquired knowledge about barcodes and scanner types to understand how scanners decode data.
The first step is capturing the data. In the case of a laser scanner, the red light illuminates barcode lines. Light reflects from the barcode to the scanner’s photoelectric cell or sensor. When illumination is detected by the sensor, it generates an analog signal, or a pattern of light impulses, and sends it to the decoder for processing. The decoder, in turn, verifies the barcode check digits and interprets them, converting them into readable text. This text is sent to a computer system that displays decoded data.
In the case of image scanners, data is captured by taking an image of the barcode. It then runs through a processing algorithm like that of laser scanners only more sophisticated. The algorithm searches for data patterns it can recognize. But as we’ve mentioned, two-dimensional imager scanners must be configured for specific “languages”. The fewer symbols a scanner recognizes, the faster it processes the image. Thus, it’s worth disabling languages that aren’t needed to improve workflow efficiency.
FAQ. Frequently Asked Questions About Scanners.
If you have any questions about barcodes and scanners, we’ll strive to answer them in this section.
Why Can’t Laser Scanners Read 2D Barcodes?
Laser scanners capture data by sensing reflections from the red diode line light. As the line itself is narrow and moves in one direction, scanners can only read a linear pattern. Two-dimensional barcodes feature a more complex pattern that must be captured fully to be processed.
Can Barcode Scanners Read Through Tape or Glass?
Yes, all barcode scanners can read codes through glass or tape. However, tape and glass can create a glare that may prevent the scanner’s sensor from detecting the barcode. You can fix this issue by simply changing the tilt of a product.
Can Scanners Read Barcodes From Any Angle?
One-dimensional barcodes can only be read from a nearly perpendicular angle, as the spacing between lines is important for decoding. Two-dimensional barcodes can be read from nearly any angle.
Why Won’t My Scanner Read Barcodes?
Even if your scanner is suitable for the type of barcodes you use, it may have trouble reading some barcodes. Laser scanners can’t read barcodes in high ambient light, low-contrast, damaged, or too small barcodes. Linear imager scanners can’t read low-contrast and damaged barcodes, or ones located too far away. Two-dimensional imager scanners, on the other hand, can easily read any type of barcode in any environment.
Which Scanner Type Is the Most Durable?
Generally speaking, all imager barcode scanners are more durable than laser scanners as they lack moving parts. However, no scanner can compare in durability with rugged handheld computers. Devices such as the Getac T800 hold military-grade certification indicating they can withstand drops to concrete, sudden shocks, submersion in chemicals, and extreme temperatures. They also feature the most advanced imager scanners that ensure accurate, high-speed barcode readability. As a great bonus, handheld computers can replace your working station, supplying a range of software, communication, and multimedia tools.
Contact Barcode Scanner Specialists
Now that you know how barcode scanners work, you can make an informed decision regarding a new scanner purchase. Modern handheld computers are a wise investment, combining the best of both worlds – barcode scanners and PCs.
Energy Electronics is a certified reseller of Honeywell, CAT, Getac, Kyocera, and other rugged scanning devices. Contact us directly for consultation or a quote. We strive to make the most appealing offers on bulk orders.
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