Barcode Scanner Guide
Which BarCode Scanner is right for my Application?
There are many forms of barcode reading devices ranging from compact lightweight scanners through to fixed-mount industrial scanners designed for conveyor belt applications. In selecting an appropriate barcode reader for your needs, you should consider:
The operating environment that the codes will be read.
The required throughput or volume of codes to be read.
The distance at which the code should be read.
Any existing bar code symbologies.
Handheld or fixed position readers.
The print quality of code to be read.
The level of training required.
Brief Descriptions of several popular code reading technologies follow:
These Pen-type readers were the first forms of scanners commonly used in libraries and required the person holding the pen to move the tip across the bars of the code at a relatively uniform speed. The light in the tip would then reflect off the bars and spaces with different intensity and this was picked up with a photodiode also mounted in the tip. This pulsing of the reflected light was picked up in the pen as a waveform that was used to measure the widths of the bars and spaces. Similar to Morse Code dots and dashes the waveform was passed back to a decoder that generated the read output. The use of this type of reader required some patience and practise to become prolific.
CCD (Charged Coupled Device)
The CCD scanner is a relatively new device (compared to the Pen-type) and is today often used in retail or office automation. The CCD reader is another form of handheld device but is far more ‘aggressive’ than the Pen wand. Initially, these were considered contact devices and were limited by a short read range. Nowadays with technology improvements, this is no longer the case. The latest CCD readers can read a barcode at a distance of up to several meters.
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. Traditional CCD readers had one definite disadvantage: the aperture of the input device limits its reading capabilities. Typically a CCD would have either a 60mm or 90mm head and Barcodes wider than these dimensions could not be read, however with the latest extended range CCD technology this too has been eliminated as an issue.
The extended range CCD Scanners now enables the reading beam to fan out and cover all likely bar code sizes – similar to Laser Scanners.
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 bar code whereas pen or laser scanners are measuring reflected light of a specific frequency originating from the scanner itself.
A CCD requires generally less operator training and gives a higher throughput than a wand. With no moving parts, they are also considerably cheaper than other technologies.
Hand Held Laser Scanner
These are probably the most popular barcode reading device. In earlier times Lasers were also far more aggressive than a CCD, have greater reading distance and could generally read poor quality bar codes. CCD scanners have now caught up and can generally match reading performance.
A typical laser scanner can read at a distance of between 15cm to 70cm whilst long range variants can read at a distance of up to 10mtrs. Reading on irregularly shaped surfaces is also achievable with this technology. Instinctively an operator will require little training. Laser scanners work the same way as pen type readers except that they use a laser beam as the light source and typically employ either a reciprocating mirror or a rotating prism to scan the laser beam back and forth across the bar code. As with the pen type reader, a photodiode is used to measure the intensity of the light reflected back from the bar code. With scan speeds at up to several hundred scans per second, the throughput is high. Because the scan rate is above 20 cycles per second, the human eye’s persistence of vision gives the impression of a continuous line, rather than a moving spot is being projected. With a Laser scanner, the use of motors or moving parts to achieve the reflected beam increases the cost of manufacture and hence the cost of purchasing these tends to be higher than other scan technologies.
Presentation/Omni-Directional – Hands-Free Scanners
More commonly found in the supermarket sectors, this type of scanner will be either in counter mounted or positioned vertically. Omni-directional scanning uses a series of straight or curved scanning lines of varying directions in the form of a starburst, a lissajous pattern, 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. Omni-directional scanners almost all 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 Omni Scanners use a single rotating polygonal mirror and an arrangement of several fixed mirrors to generate their complex scan patterns.This setup is ideal for retail outlets because the checkout operator does not have to align the bar code to the laser beam; the scanner projects a very aggressive scan pattern. This scanning method is ‘hands-free’ as the operator does not hold or manipulate the scanning device in any way.
Technology improvements continue in all scanning sectors and presentation scanning is no different. New Presentation Scanners are now being released that use image technology to view and read the barcode on the products. This technology promises to provide more economical devices as it does not require moving parts or motors to achieve the hands-free scan.
Imaging scanners are the fifth and newest type of barcode reader. They use a camera and image processing techniques to decode the barcode. Image scanners 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. These are special scanners designed to read both stacked and matrix 2-D symbologies in addition to linear codes. In this type of scanner, no lasers are used. When the operator depresses the trigger, an illumination system is momentarily activated and a ‘picture’ is taken. A digital signal process chip, high-resolution array, and software decoding algorithms find and decode the symbol.
Direct Parts Marking Scanner
Tracking individual components can be a costly proposition when standard product labeling techniques fail to measure up over time. Direct Part Marking (DPM) provides a permanent marking solution that ensures readability throughout the life of the products, even when subjected to harsh environments during the manufacturing process. DPM Scanners are able to capture images and read virtually all 1D and 2D barcodes and direct part marks (DPM) — including dot peen. These highly versatile devices are ideal in industries that depend on a wide variety of data types, such as healthcare, aerospace and automotive.
Unattended Scanning Systems
Also known as ‘Fixed Mount’ Scanners, these are a robust mounted scanner suitable for Low to medium Speed conveyor systems and other automated scanning requirements. Some models feature auto-focus combined with inbuilt oscillating mirrors to cover large surface areas and varying distances – permitting a variety of package sizes and shapes to be scanned automatically even with changing barcode positions.
Models range from low-cost CCD units to high-end laser-based and image 2D readers. Particularly suited to manufacturing, transportation, and logistics, and distribution industries.
Also known as mobile scanners, these scanners use various wireless protocols such as; Bluetooth, 433MHz or propriety radio signals to connect the scanner back to a host connection via a wireless signal. In most cases, a base station is used to provide the interface connection suitable for the host and also double up as a charger for the scanner when not being used. Some of the latest cordless scanners have become very advanced and now feature small LCD screens so that the scan data can be viewed and others even feature small keyboards so that data can additionally be key entered.
Cordless scanners are available in all the latest scan engine formats, CCD, Laser, and even the new 2D imager formats. Units essentially differ in the range that the scanner can transmit and this can vary from 3 meters up to 100 meters – so it’s important to buy the right unit for your requirement.
Can I use a Barcode Scanner on my existing Computer System?
Barcode Scanners can be connected to a host system in several ways. Most barcode readers can output the data in a variety of interfaces. The scanner is either purchased with the correct interface or in many cases can have the interface cable to suit your requirement attached and the interface setting enabled by scanning a setup barcode – it’s that simple!
Common Scanner Interfaces:
USB – Universal Serial Bus is a plug and play method that allows many peripherals to be connected to a single port. It replaces all kinds of serial and parallel connectors. With USB compliant PC’s and scanners you just plug them in and turn them on, USB makes the process automatic.
The plug and play USB method sets the scanner up as a wedge device – anything you scan appears where the cursor sits, as if the data was keyboard entered. Alternatively, the USB port can also be enabled to emulate a serial port connection (Com Port). This type of connection is used when an application monitors a defined com port for a data entry. In this method, the scan will appear in a dedicated field within your application. As a USB port is a powered connection, the scanner is powered from this connection and does not require an external power source.
Keyboard wedge – the bar code reader or decoder connects between the keyboard and the base unit of the PC. Data is sent to the PC as though it has come from the keyboard. If a USB port is used as a plug and play device – the USB port will direct the data to the screen in the same way. As a keyboard wedge port is a powered connection, the scanner is powered from this connection.
RS232 – is an industry standard protocol for data transfer between two peripheral devices. The specification allows for data transfer from one transmitting device to another at relatively slow data rates (up to 38.4K bits/second) and short distances (up to 50ft). RS232 port connections do not allow the data to be displayed to the screen cursor position as with a wedge connection, instead, the application needs to be designed to view the required com port to receive the data. With today’s obsession with miniaturisation, most PC’s are no longer supplied with an RS232 interface. If you have an older Scanner with an RS232 interface – these can still be used by acquiring an RS232 to USB dongle. It is also important to note that with RS232 the attached scanner must be powered by an external source as unlike wedge and USB these are in most cases an unpowered interface.
Wand emulation – outputs the data as an analog signal, which requires decoding before being sent to the host system. Scanners that output wand data rely on the connected decoder to then provide the required output to suit your required connection. Wand emulation was most commonly used with Pen Wands and these are rarely used in modern systems anymore. As a wand decoder port is a powered connection, the scanner is powered from this connection.
Note: Additional interfaces, such as Ethernet and RS485, are available through the use of third party devices. In these cases an RS232 interface scanner is usually fed into the device which then converts the signal into the appropriate format.
At Intermax we have the largest range and the knowledge to put the right equipment in your hands.
If you need any assistance or would like a demonstration – give our sales staff a call or request additional information online!