Technological advancement has transformed all types of applications. In the world of scanning technology, laser scan engines were till recently, considered to be the most powerful and applicable in all types of scanning applications. But these too have been overtaken by 1D and 2D imagers that are not only more reliable but also more powerful. They are therefore being used with a larger number of devices needing the additional capability of scan engines.
There are two conflicting views about the best technology for a handheld barcode scanner. Those linked to laser scanners are convinced that lasers are the best, while those familiar with imaging techniques feel that this is more reliable, versatile and gives value for money.
The truth about which technology is the best, is determined by the environment where it is used. All technologies are very effective in the functioning they are meant for, with the basic requirement of being used in the appropriate environment in which they are suitable. Both laser and imaging technologies have been in use since their inception several years ago, and constant innovations and upgrades have made them suitable for the newest applications. But imaging technology has proved itself to be superior now with the latest developments that have enabled it to read various types of barcodes, and hence its applicability has been broadened.
All this changes the market scenario for scanners, and it is difficult to gauge which scanner would prove to be best for your application. The following guide would help in deciding which one would prove to be the best for the application in question.
Linear imagers use what is commonly referred to as CCD Technology or charge coupled device. The CCD when used in a linear imager, captures varying levels of reflected light from the bars and spaces found in a barcode, and then converts them into video signals. The solid state components in use are also found in gadgets like image capture devices and simple scanners, examples of which include simple fax machines and sophisticated gadgets like digital and video cameras and linear imagers.
Linear Imagers need a source of light of their own to provide optimal performance. This comes from low-power, long life light emitting diodes or LEDs. The light can be switched all the time since it barely consumes power and has a long lifespan without any trigger required to switch it on. Some scanners do have triggers in their design along with sleep modes for saving power particularly when battery operated devices are in use.
Linear Imagers are considered more reliable than laser scanners since they are solid state devices. Laser imagers use very fast moving mirrors to move the beam across the entire barcode. The laser imager illuminates the barcode with light from the LED and then its lens helps to focus the image of the barcode onto the CCD component of the imager. The barcode data is received through the application of one or many algorithms after the simple process of reading identifies the troughs and peaks in the signal. The process is enabled by the analog-to-digital converter as well as the software used by the processor. The pace at which this process takes place depends on the speed of the processor and the software efficiency. Thus the user may find the scanner "snappy" or slow.
Linear imaging technology is not new and has been in use for a long time, but it is the most recent advances made in this type of technology that have made its performance far superior than ever before. The next generation of imagers use refinements and advanced ways of reading video signals, have special decode software and hardware that enhance speed, read success rates and depth-of-field. This enables them to scan damaged and poor quality barcodes also with ease.
Laser scanners have for long been considered to be good performers mainly due to the scanning range they offer since they can read barcodes from a distance of several feet. Large symbol prints can make scanning possible from even 35 ft. They use a laser beam along with oscillating mirrors that help to move the beam forwards and backwards across the barcode in question. A number of configurations are available to meet the requirements of a diverse range of scanning applications. Thus they could be standard range, long range, high density, wide angle or high visibility etc. Laser scanners are particularly helpful for scanning applications from forklifts in a warehouse, since barcodes can be read without having to get off the forklift each time.
Secondly, lasers can be focused on a very small beam, and due to its single frequency or the light being coherent, the beam does not spread too much over the prescribed distance. This enables the diameter of the beam to remain small despite the wide scan range.
However, the flip side of laser scanners is that they are more expensive than linear imagers, and their moving part, the oscillating mirror loses its alignment over a period of time, which in turn, affects scanning performance. Laser scanners also pose safety risks. Europe is voicing its concern over high-energy lasers affecting eyes, and the US is concerned about the safety of children with laser scanners entering homes for use in e-commerce applications.
Both laser scanners and linear imagers are available as fixed and handheld devices. Handheld units function at lower scanning speeds since they are mainly used for scanning stationary symbols. This could be in the range between 35-300 scans per second. Fixed position scanners are the high-end speed scanners since they are attached on conveyors and must rapidly scan before it crosses the symbol to be scanned. The speed here is as high as 600-1800 times per second.
The Scanner Selection Process
Both laser scanners and linear imagers have some common features and deliver good results but both also have some unique features that make them ideal for specific ones. Hence the selection must be based on the basis of the scanning application in question-does it entail scanning from a distance, what kind of barcodes have to be scanned, the work environment and the budget allocated. Thus the deciding factors include:
- The scanning distance and the product to be scanned. Linear imagers deliver excellent results at ranges less than 18 inches while lasers are more suitable for distances greater than 18 inches.
- The barcodes to be scanned. Both scanners can read all major symbologies like Code 128, Code 39 and EAN/UPC. However, the latest linear imagers are perfect for codes with greater code densities with narrow bar width between 2-5mil and with code width till 8 inches for the X-dimension between 10-20 mil.
- The source and condition of the barcode to be scanned. Here again linear barcodes are better scanners since they can read poorly printed ad damaged barcodes.
- The environmental conditions in which the scanner is to function. Scanners that are solid state ones without any moving parts are safer and damage free. Therefore linear imagers are trusted more than laser scanners that are equipped with moving mirrors to capture the barcode image.
- For reading barcodes off computer screens, linear imagers prove to be better suited especially in applications like configuring a number of devices.
- Snappy performance is expected from scanners and here the linear imager again proves better except in cases where codes have to be scanned from a greater distance.
Keeping in view these factors, the best scanner can be selected with ease.
Take a look at the selection of handheld barcode scanners here.