5 Types of Barcode Readers for Use in Automation

In the late 1940s, a grocery chain from Philadelphia approached the Drexel Institute of Technology to develop custom automation that could store and read information about products during checkout. A teacher at the institute – Norman Joseph Woodland – took up the task, experimenting with various data collection methods. He eventually found one that worked, a technique that utilized Morse code to represent an assigned number for the product. Instead of the typical dots associated with Morse code, however, he extended these into lines to create a linear code.

Woodward adapted a tubelike mechanism from a movie sound system that was developed in the 1930s to help detect a movie projector’s light and convert it into sound. He adjusted it through precision automation, engineering it so that it instead converted light into numerical form. This custom automation device became the precursor for barcode scanners. Although he eventually patented the device in 1952, it wasn’t put to use until 1973, when an Ohio supermarket scanned its first item, a pack of gum.

What Exactly is a Barcode?

In essence, a barcode is simply a pattern applied to components, goods or packages that allows machines to read it. These barcodes contain information about the products, and are used for tracking purposes throughout an item’s lifecycle. To read the information from these barcodes, a special scanner that uses lenses and lights decodes the data that this pattern represents.

When used in manufacturing, automation transfers this information to a database, which helps log and track products throughout the manufacturing and distribution processes. Barcodes are now used to quickly identify products in nearly every industry, including to automate and simplify tracking of products through the supply chain

They can show:

• Where an item was produced
• Where a product was shipped
• To which retailer the merchandise was sold
• Time, data and price charged for the goods

While all this can be done manually, barcodes offer better accuracy, while also simplifying sorting and traceability. This custom automation can also be applied to reduce liability and heighten safety, as it allows defective products that reach store shelves to be quickly identified, accelerating safety recalls while also making data regarding quality control available throughout the supply chain.

How Barcode Readers Work

There isn’t just one type of barcode reader, so understanding how barcodes work differs depending on the method of automation. Engineering of barcode readers also varies based on the marking or printing methods involved in making these barcodes. To understand how barcodes work in both retail and manufacturing, automation between barcodes and readers must be appropriately synchronized.

Types of Barcodes

There are dozens of barcode formats, with thirty major ones, though they can be separated into two basic categories. Those made up of a row of lines is referred to as 1D – or one-dimensional – barcodes. Meanwhile, 2D – or two-dimensional – barcodes are made up of dots and squares. 2D codes invariably contain more data than 1D codes, which store data only horizontally, as their vertical patterns also hold information.

1D Barcodes

Using numeric or alphanumeric data, 1D barcodes were the first type utilized globally. These linear codes are usually read from left to right, storing information horizontally, with each character representing a different aspect of the merchandise in a database that defines each character’s meaning. The width of each space and bar relates directly to specific characters, with quiet zones – those white spaces to the right and left of the barcode – helping the reader locate the barcode. These zones generally occur at least seven times through the narrowest part of the barcode.

Bars in the code work according to the ratio between their width and that of the narrowest bar, with common ratios being 2:1. 2.5:1 and 3:1. These ratios describe the width of quiet zones compared to that of the black bars, basing these ratios from the starting point of the narrowest of the black bars in the code. Some barcodes include what’s called a guard pattern, which shows where the barcode begins and ends.

Commonly used 1D barcodes include:

• Codabar barcodes are used when serial numbers are required, including for blood banks and delivery services as well as for membership cards.
• Code 128 barcodes can encode 128 characters in numeric or alphanumeric formats, and they’re used for various medical applications, shipping labels and ID cards as well as by the United States Postal Service (USPS).
• Code 39 barcodes are used widely for military purposes, badges, industrial applications and inventory.
• EAN (European Article Number) barcodes are standard in the European Union, used to identify specific retail goods, along with how they’re packaged and their manufacturer.
• GS1 barcodes are used universally in the logistics industry to identify goods, pallets and places they’ve traveled along the supply chain.
• Interleaved barcodes use only a numeric format, employed for encoding number pairs into a high-density self-checking format.
• POSTNET barcodes are used by the USPS for direct mailing.
• UPC (Universal Product Code) barcodes are used for consumer and retail products.

Most 1D barcodes also include a check digit that’s used to verify that the code isn’t missing information or damaged, and that it’s complete.

2D Barcodes

With capabilities for coding information vertically as well as horizontally, 2D barcodes store far more data. Single 2D barcodes can contain 2335 alphanumeric characters or 3116 numeric characters, in comparison to 39 characters for the 1D barcode Code 39. Additionally, 2D barcodes have custom automation capabilities that allow them to correct errors and help eliminate misreading.

2D barcodes also have quiet zones similar to 1D codes, though these surround the entire code. These barcodes also feature finder and clocking patterns that identify where the code begins and where it ends. Finder patterns are L-shaped, located on the outside edge along two sides of the barcode, which ensures they’re properly oriented when being read. Clocking patterns are opposite of finder patterns, with alternating black and white cells in a series defining the size of single cells and the barcode being decoded.

Commonly used 2D barcodes include:

• Aztec barcodes are used by vehicle rental companies and ticket agencies.
• Data Matrix barcodes are used in the print media, defense and aerospace industries, as well as by the USPS.
• MaxiCode is used for logistics, with its code based on dots.
• QR (Quick Response) barcodes are used for commercial marketing applications and in the automotive industry.

2D barcodes tend also to have more redundancies, with Data Matrix codes typically having data encoded thrice, which considerably reduces the chance of an incorrect reading.

Types of Barcode Readers

Barcode readers – also known as barcode scanners – are devices with sensors, lights and lenses that decode the data within a barcode. The first 1D barcode scanners used lasers and oscillating mirrors (or prisms that rotated), with the laser beam scanning back and forth along the barcode. A photodiode measured light reflected from the barcode, creating an analog signal that was then converted into a digital signal.

All coding takes place by collecting information from a central database that includes manufacturing data, with the barcode then applied to a label on, or directly to, the object. These typically utilize thermal or inkjet printing methods, with codes placed via direct part marking (DPM). These include custom automation techniques such as chemical etching, dot peen or laser marking.

There are five basic types of barcode readers:

• Slot scanners: A stationary barcode reader, they require users to pull items by hand through a slot in the device. These readers are typically used for reading cards that require swiping, including ID cards.
• Pen wands: As the simplest and least expensive barcode reader, pen wands have no moving parts, so tend to last longer than other readers. Though durable, these readers require direct contact with the code, must be held at a certain angle to read data and read data only when it passes over the barcode at a certain speed.
• Laser scanners: Used either as stationary or handheld devices, they don’t need to be close to the barcodes they read, with typical models able to read from 24 inches (about 61 cm) away and longer-range models reading as far as 30 feet (about 9.1 m) away. Using lenses and mirrors, they read barcodes regardless of their orientation and in a single second can process up to 500 scans.
• Image scanners: Also referred to as camera readers, these readers feature small cameras that capture the barcode’s image. Featuring digital imaging processors, they can read barcodes from a distance of about 9 inches (about 23 cm).
• CCD (charge-couple device) scanners: Often used in retail, these readers use a gun-like interface. With better range than pen wands, these devices still need to be close to the items they’re reading, though they can only read barcodes as wide as their face.

EAM Custom Automation: Engineering Logistics Labelling

EAM Inc. designs, manufactures and installs a variety of packaging and logistical equipment and accessories. This includes the company’s EAM Cooper Feeder, which encodes barcodes and supports barcode readers.

Features of the EAM Cooper Feeder include:

• Adjusts easily to product widths
• Auxiliary handshaking and triggers available for barcode readers
• High-speed feeding system for cards
• Intuitive set-up through OIT (Operator Interface Terminal) touch screen for batches, counts, spacing and speeds
• Labor Ready! integrated encoder with trigger outputs

For more information on our Cooper Feeder or other custom automation products, contact us today.

Electronic device

A barcode reader or barcode scanner is an optical scanner that can read printed barcodes, decode the data contained in the barcode on a computer. Like a flatbed scanner, it consists of a light source, a lens, and a light sensor for translating optical impulses into electrical signals. Additionally, nearly all barcode readers contain decoder circuitry that can analyse the barcode's image data provided by the sensor and send the barcode's content to the scanner's output port.

Types of barcode scanners

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Technology

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Barcode readers can be differentiated by technologies as follows:

Pen-type readers

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Pen-type readers consist of a light source and photodiode that are placed next to each other at the tip of a pen. To read a barcode, the person holding the pen must move the tip of it across the bars at a relatively uniform speed. The photodiode measures the intensity of the light reflected back from the light source as the tip crosses each bar and space in the printed code. The photodiode generates a waveform that is used to measure the widths of the bars and spaces in the barcode. Dark bars in the barcode absorb light and white spaces reflect light so that the voltage waveform generated by the photodiode is a representation of the bar and space pattern in the barcode. This waveform is decoded by the scanner in a manner similar to the way Morse code dots and dashes are decoded.

Laser scanners

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Laser barcode scanners utilize a semiconductor laser diode to produce a laser beam. This beam is directed by a deflection mirror onto a polygon mirror wheel. The design may include a focusing device, enabling the scanner to adjust the beam to scan at various distances.[1]

The scanner deflects the laser beam using a rotating mirror wheel. This wheel deflects the beam line by line over the barcode at frequencies between 200 Hz and 1200 Hz in most scanners. The deflected beam exits the scanner spread at an opening angle, which is dependent on scanner design. The deflection allows it to traverse the barcode in a reading plane, effectively turning it into a "reading beam." To accommodate stationary items, laser scanners incorporate oscillating mirrors that provide additional deflection perpendicular to the main scanning line. These mirrors function at frequencies that can vary from 0.1 Hz to about 5 Hz, ensuring that barcodes can be read at different orientations.[1]

Photodetector receives light through the optical system consisting of the mirror wheel and an optical filter. The reflected light, rapidly varying in brightness with a data pattern, is then converted into an electrical signal and is subsequently amplified to a usable level for digital processing.[1]

CCD readers (also known as LED scanners)

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Charge-coupled device (CCD) readers use an array of hundreds of tiny light sensors lined up in a row in the head of the reader. Each sensor measures the intensity of the light immediately in front of it. Each individual light sensor in the CCD reader is extremely small, and because there are hundreds of sensors lined up in a row, a voltage pattern identical to the pattern in a barcode is generated in the reader by sequentially measuring the voltages across each sensor in the row. The important difference between a CCD reader and a pen or laser scanner is that the CCD reader is measuring emitted ambient light from the barcode, whereas pen or laser scanners are measuring reflected light of a specific frequency originating from the scanner itself. LED scanners can also be made using CMOS sensors, and are replacing earlier Laser-based readers.[2][better source needed]

Camera-based readers

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Two-dimensional imaging scanners are a newer type of barcode reader. They use a camera and image processing techniques to decode the barcode.

Video camera readers use small video cameras with the same CCD technology as in a CCD barcode reader except that instead of having a single row of sensors, a video camera has hundreds of rows of sensors arranged in a two dimensional array so that they can generate an image.

Large field-of-view readers use high resolution industrial cameras to capture multiple bar codes simultaneously. All the bar codes appearing in the photo are decoded instantly (ImageID patents and code creation tools) or by use of plugins (e.g. the Barcodepedia used a flash application and some web cam for querying a database), have been realized options for resolving the given tasks.

Omnidirectional barcode scanners

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Omnidirectional scanning uses "series of straight or curved scanning lines of varying directions in the form of a starburst, a Lissajous curve, or other multiangle arrangement are projected at the symbol and one or more of them will be able to cross all of the symbol's bars and spaces, no matter what the orientation.[3] Almost all of them use a laser. Unlike the simpler single-line laser scanners, they produce a pattern of beams in varying orientations allowing them to read barcodes presented to it at different angles. Most of them use a single rotating polygonal mirror and an arrangement of several fixed mirrors to generate their complex scan patterns.

Omnidirectional scanners are most familiar through the horizontal scanners in supermarkets, where packages are slid over a glass or sapphire window. There are a range of different omnidirectional units available which can be used for differing scanning applications, ranging from retail type applications with the barcodes read only a few centimetres away from the scanner to industrial conveyor scanning where the unit can be a couple of metres away or more from the code. Omnidirectional scanners are also better at reading poorly printed, wrinkled, or even torn barcodes.

Cell phone cameras

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While cell phone cameras without auto-focus are not ideal for reading some common barcode formats, there are 2D barcodes which are optimized for cell phones, as well as QR Codes (Quick Response) codes and Data Matrix codes which can be read quickly and accurately with or without auto-focus.[4]

Cell phone cameras open up a number of applications for consumers. For example:

• Movies: DVD/VHS movie catalogs.
• Music: CD catalogs – playing an MP3 when scanned.
• Book catalogs and device.
• Groceries, nutrition information, making shopping lists when the last of an item is used, etc.
• Personal Property inventory (for insurance and other purposes) code scanned into personal finance software when entering. Later, scanned receipt images can then be automatically associated with the appropriate entries. Later, the barcodes can be used to rapidly weed out paper copies not required to be retained for tax or asset inventory purposes.
• If retailers put barcodes on receipts that allowed downloading an electronic copy or encoded the entire receipt in a 2D barcode, consumers could easily import data into personal finance, property inventory, and grocery management software. Receipts scanned on a scanner could be automatically identified and associated with the appropriate entries in finance and property inventory software.
• Consumer tracking from the retailer perspective (for example, loyalty card programs that track consumers purchases at the point of sale by having them scan a QR code).

A number of enterprise applications using cell phones are appearing:

• Access control (for example, ticket validation at venues), inventory reporting (for example, tracking deliveries), asset tracking (for example, anti-counterfeiting).[5]
• Recent versions of the Android, iOS, and Windows Phone mobile phone operating systems feature QR or barcode scanners built in, usually accessible from their respective camera application.

Housing

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Barcode readers can be distinguished based on housing design as follows:

Handheld scanner

with a handle and typically a trigger button for switching on the light like this are used in factory and farm automation for quality management and shipping.

PDA scanner (or Auto-ID PDA)

a PDA with a built-in barcode reader or attached barcode scanner.

Automatic reader

a back office equipment to read barcoded documents at high speed (50,000/hour).

Cordless scanner (or Wireless scanner)

a cordless barcode scanner is operated by a battery fit inside it and is not connected to the electricity mains and transfer data to the connected device like PC.

Barcode library

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Main article: Barcode library(or Barcode SDK)

Currently any camera equipped device or device which has document scanner can be used as Barcode reader with special software libraries, Barcode libraries. This allows them to add barcode features to desktop, web, mobile or embedded applications. In this way, combination of barcode technology and barcode library allows to implement with low cost any automatic document processing OMR, package tracking application or even augmented reality application.

Methods of connection

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Serial interfaces

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Early barcode scanners, of all formats, almost universally used the then-common RS-232 serial interface. This was an electrically simple means of connection and the software to access it is also relatively simple, although needing to be written for specific computers and their serial ports.

As the PC with its various standard interfaces evolved, barcode readers began to use keyboard serial interfaces. The early "keyboard wedge" hardware plugged in between the PS/2 port and the keyboard, with characters from the barcode scanner appearing exactly as if they had been typed at the keyboard. Today the term is used more broadly for any device which can be plugged in and contribute to the stream of data coming "from the keyboard". Keyboard wedges plugging in via the USB interface are readily available. In many cases, a choice of USB interface types (HID, CDC) are provided.

Proprietary interfaces

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There are a few other less common interfaces. These were used in large EPOS systems with dedicated hardware, rather than attaching to existing commodity computers. In some of these interfaces, the scanning device returned analog signal proportional to the intensities seen while scanning the barcode. This was then decoded by the host device. In some cases the scanning device would convert the symbology of the barcode to one that could be recognized by the host device, such as Code 39.

Wireless networking

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Some modern handheld barcode readers can be operated in wireless networks according to IEEE 802.11g (WLAN) or IEEE 802.15.1 (Bluetooth). Some barcode readers also support radio frequencies viz. 433 MHz or 910 MHz. Readers without external power sources require their batteries be recharged occasionally, which may make them unsuitable for some uses.

Resolution

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The scanner resolution is measured by the size of the dot of light emitted by the reader. If this dot of light is wider than any bar or space in the bar code, then it will overlap two elements (two spaces or two bars) and it may produce wrong output. On the other hand, if a too small dot of light is used, then it can misinterpret any spot on the bar code making the final output wrong.

The most commonly used dimension is 13 mil (0.013 in or 0.33 mm), although some scanners can read codes with dimensions as small as 3 mil (0.003 in or 0.075 mm). Smaller bar codes must be printed at high resolution to be read accurately.

See also

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References

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• Barcode scanners at Wikimedia Commons