2011年4月20日星期三

Barcode-Scanners

Barcode scanners are used in a variety of environments, including retail, industrial, and health care. Though within this range a bar code scanner fulfills a variety seemingly unrelated tasks, from scanning groceries, confirming package delivery, to scanning patient wristbands, the final result of all of these bar code scans is, in essence, the same. What the barcode readers are doing is reading and collecting information held within the barcode itself. With so many applications for barcode scanners and so many types available, the first step in understanding the differences in the barcode scanners is understanding what it is that they are actually doing.



In its most basic form, a barcode scanner deals with light wavelength absorption and reflection. The black and white bars or dot matrix that a bar code it made up of dictates areas the light emitted from the scanner that will be be absorbed into the white of the label and areas that will be reflected back from the black to the barcode scanner. Other components of barcodes that the bar code reader deals with are the ?x? dimension of the barcode and the quiet zone of the barcode. The ?x? dimension is the basic way to measure barcode, which is done by measuring the smallest bar on the barcode. The unit in which barcodes are measures are mil, which is 1/1000 inch. For example, if the smallest bar on a barcode is 3 mil wide, it would be a 3 mil barcode. Some barcode scanners have difficulty reading very small or very large barcode. The quiet zone is the white area surrounding the barcodes. This leaves an area of rest surrounding the barcode so that unrelated reflections are not collect.



Another step to understanding bar code scanners is knowing what types of barcodes exist. Essentially, there ,zxcsky09543, are three main categories of barcodes symbology, which are numeric only, alpha-numeric, and two dimensional barcodes. Within these three categories, there are a range of types of barcodes with a variety of configurations and uses. All of these barcodes utilize specialized software to allow the computers interpret the information.



An example of a numeric only barcode is a Universal Product Code, or UPC. This barcode is scanned by the barcode scanner. The number collected then allows the computer database to pull up the product information, including the products name and price. A UPC must be loaded into the database being used for the product information to be available. Numeric barcodes are 1D barcodes.

1D barcodes can be read by 1D and 2D barcode readers. Alpha-numeric barcodes, which are also 1D barcodes, are able to hold more information than a numeric barcode, though the data is retrieved the same way through the computer database. An example of an alpha-numeric barcode is the Code 128 barcode which is used world wide for shipping and packaging.



The third category of barcode symbology is 2D barcodes, which require a 2D barcode scanner to be read. 2D barcodes are able to hold a much denser amount of data than either of the 1D barcode categories. This is because the 2D barcodes are, in essence, multiple 1D barcodes stacked on each other. With the correct barcode scanner and software, 2D barcodes have the ability to hold actual information within the barcode itself, not just a reference number to a database. An example of 2D barcodes are maxicode barcodes which are used by UPS. These barcodes were designed to hold around 80 characters, which is able to hold most standard addresses.



After understanding how the barcodes and , http://www.laptopbatterylot.com, barcode scanners communicate with each other, the types and uses of bar code scanners starts to be more understandable. The four basic categories are Barcode Wand, Charged Coupled Devices, Imager Barcode Scanners, and Laser Bar code Scanners.



The wand scanner is the most basic available and works well for low volume 1D bar code scanning. They are relatively inexpensive, but barcode wands tend to be sensitive when in operations, requiring contact between barcode and barcode scanner for a successful scan. The Charged Coupled Device, or CCD, is a much more aggressive barcode scanner than the bar code wands. This means that contact is not necessary for a successful scan. The CCD is limited by its depth for field and width of range with reading barcodes. The Imager Barcode Scanner is an improved version of the CCD Barcode Scanner. It has more aggressive scanning power and a larger depth of field than the CCD. Also, the Imager Bar Code Scanners are capable of reading both 1D and 2D barcodes. Laser Bar Code Scanners have the largest depth of field among the types of barcode scanners. They are the most aggressive type of scanners and the most popular as well. A laser barcode scanner with an extra long range can be capable of reading barcodes up to 30' away.



Even broken down into these four categories, there are still a wide range available, for example, options of cordless barcode scanners which are equipped with Bluetooth wireless capabilities. How and where the barcode scanner is going to be used will determine what kind of barcode scanner will work best. Options come in hand held and hands free styles, corded or cordless barcode scanners, barcode scanner embedded in a counter top, heavy duty industrial, and omni directional barcode scanners.

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