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Bar Code Scanners

Laser versus CCD scanner

Laser scanners are generally more expensive than CCD scanners, but can often be more efficient in their scanning ability. They can be designed to read barcodes from a great distance, allowing workers to scan items on the top shelf of a warehouse without having to move closer to the item. These scanners are also a better option when the barcode is not on a flat, hard surface as CCD scanners are used in close contact situations.

Laser Scanners can also have different options for the distance you need to scan, such as standard, long range, and extra-long range.

CCD scanner are often more durable as they have no moving parts (lasers have mirrors that can miss align). A situation for a CCD scanner may be a bright location, typically outside, where placing the scanner directly over the barcode will block out most outside light giving a quicker and more accurate read.

What are the scanner interfaces? (Keyboard wedge, USB, Serial)

Keyboard Wedge

This type of barcode reader is attached through the keyboard interface, the barcode reader sends data exactly as if you pressed the keys on the keyboard. No special drivers are required. It is called “Wedge reader” because they physically wedge between the keyboard and computer. To install a wedge, you unplug the PS2 keyboard from the PC and plug it into the keyboard wedge. The cable coming from the keyboard wedge plugs into the computer where the keyboard was plugged in. The scanner uses the power from the keyboard cable, so no external power is needed.

USB

USB scanners are similar to the keyboard wedge reader above, but use the USB interface. Again no special driver is required and the data is placed directly in the keyboard buffer. It is convenient to use with a notebook because the latter does not have an external keyboard.

Only Windows 98 or above platforms (including Windows ME, 2000 and XP, Vista) supports USB configuration. The OS treats the reader as a USB keyboard and automatically places the input in the keyboard buffer.

Serial Port

The barcode reader is connected to one of the serial ports of the computer (usually COM1 or COM2). Software is needed to retrieve the information. This can can be built into your existing application or using software provided with the scanner. An external power adapter is required for operation. Your COM port setting must match that of the scanner to achieve communication.

Bar Code Verifiers

Why use verifier? Can I just use a scanner to test my bar codes?

While scanning after printing is better than not testing the bar code at all, there are some differences between a scanner and a verifier:

Scanners are designed to read the bar code, they make no judgment on the quality of the print. Scanning a bar code only assures that the scanned bar code has some region on it that is readable by that scanner. The better your scanner the more likely it is to scan a poor quality bar code

Verifiers are precision instruments that predict how well the bar code by a typical scanner (any scanner). They report on key elements of the barcode based on bar code specifications. Typical parameters include: print contrast, element widths, bar deviation. A verifier can assign a grade to the bar code or a pass/fail indicating the likely hood that that bar code will be scannable a high percentage of the time.

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