Radical changes are taking place in the scanning technology. Fresh imaging scan engines such as linear imagers and 2D imagers which are more potent and reliable have outdone laser scan engines. It also allows the scan engines to link to various types of devices. Which technology is appropriate for handheld scanners? The laser exponents argue laser is better while imaging supporters flaunt its exceptional importance, reliability and versatility.

How to select the appropriate scanner for an application? Follow this guide.

Linear Imagers

A charge coupled device (CCD) is the fundamental technology of a linear imager. The CCD seizes various levels of light reflected from the bar and spaces of the barcode and transforms into a video signal.

Linear imagers uses self light source, the low-power durable light emitting diodes (LEDs) which keeps the light on always. It does not require a trigger for saving power.

Due to its solid-state, linear imagers are more dependable than laser scanners. To scan a barcode, a linear imager lights it up with LED and focus its image onto the CCD component using lens. Then the peaks and troughs of the signal are detected and decode algorithms are used to obtain the barcode data. The analog-to-digital converter of the scanner and the processor software performs this task and its pace depends upon processor speed and competence of the software.

Makers of modern-day linear imagers have incorporated advanced methods of scanning video signals and unique decode hardware/software to enhance speed and success rates. Faster scan rates and speedy processors help linear imagers scan cheap and laminated barcodes easily.

Laser Scanners

They scan barcodes with a laser beam combined with oscillating mirrors which automatically passes the beam to and fro across the barcode. For different scanning systems, various configurations of laser engines are available. Laser scanners have high scan range and can read from 35 feet away.

Lasers can be fixed on small beams. The beam will not extend beyond a given distance as the light is coherent. So its diameter will stay small enough to cover broad and slender bars of the barcode in different scan-ranges.

But lasers are costlier than linear imagers. In course of time, the oscillating mirror can get displaced and hamper the quality of scanning. Eyes can get affected by its high-energy lasers also.

Both lasers and linear imagers offer handheld and static models. The handheld ones operate at a scan speed of 35-300 times/ second. The static ones operate at a scan speed of 600-1800 times/ second to quickly read the item before it crosses the scanning area.

Criteria for selecting a scanner

Both the scanning technologies are appropriate for reading linear barcodes. One should select a scanner based on the scanning application – scan range, condition of barcodes, work atmosphere – performance and expenditure.

Scan-range

Linear imagers will be the best choice if the distance is less than 18 inches, otherwise lasers are better.

Types of barcodes

Most scanning technologies can scan the general group of barcode symbols which includes EAN/UPC, Code 39, and Code 128. The recent linear imagers scan best in areas of higher code densities for X-dimensions between 2 and 5 mil and for X-dimensions between 10 and 20 mil with code widths up to 8 inches of these barcodes.

Condition of barcode

Linear imagers can scan poor quality, faded, damaged and laminated barcodes extremely well. Their fast scan rate engines enable them to scan such barcodes and decode the complicated video signal data.

Working environment

Unlike lasers, linear imagers are solid-state devoid of any variable parts, so they are more reliable. But, suitability depends upon its casing. For retail application, a standard ABS plastic case is durable enough, while a more hard-wearing casing is required for a warehouse application.

Barcodes from computer screen

When you have to configure many devices with barcodes, linear imagers are helpful. You can directly scan the series of barcodes from the computer screen instead of taking a printout.

Performance

When any scanner scans a code, its performance can be judged on its neatness, scan-range and defined scanning zone. A linear imager performs extremely well within its scan range. Common scan rate is 100 times/second but excellent scanners offer up to 800 times/second.

Some linear imagers can scan when the scanner’s nose touches the barcode, suitable for flat surfaces. For curved, long-range ones are good. Others have scan-range of 2 inches while long-range ones can read from 18 inches away.

You should be careful about the scan line when the scan-range reduces. For laser scanners, the laser line marks it. Since linear imagers depend on the light of LEDs, it becomes difficult to determine the scan line when scan-range increases or used in direct sunlight.

Other Scanning Technologies

APS CMOS Sensors

Active Pixel CMOS Sensors (APS) are a new type of sensor which substituted the CCD used in recent linear imagers. It joins the digital signal machine and the light detector into a single ASIC. Linear imagers with APS sensor perform the same function as those with CCD sensors, but these are smaller, more dependable and require less power.

2D Image Readers

They scan two-dimensional or linear barcodes and uses modern decode algorithms to process them. It provides Omni-directional scanning for linear barcodes. CCD or highly-developed CMOS technology can be incorporated in a 2D imager. CMOS requires very less power and performs well. CMOS- incorporated 2Dimagers are appropriate for transferable data collection in storehouse, manufacturing and retail applications where changing or recharging of batteries lowers productivity during working hours.

RFID

Radio Frequency Identification does not require line-of sight scanning as in bar coding. The RFID chips include an application-specific integrated circuit (ASIC). The ASIC is an active moving database which can be written or read in every stage along the supply chain. RFID reads and collects data at a faster rate from the RFID tags which can be attached to anything. Since forging is difficult, RFID is very secure.

Now this technology complements barcodes, but it possesses the capability to substitute them in applications. In near future, barcode scanners and RFID exponents will facilitate workers to use either technology with a single device.