What is a Bar Code?

Bar Code represents  a different way of encoding numbers and letters by using a combination of bars and spaces of varying widths. This is just another way of entering data into a computer. A bar code does not contain descriptive data. It is a reference number which  computer uses to look up an associated record that contains descriptive data and other important information. For example, a barcode found on a soda can not contain the product name, type of soda, or price, instead, it contains a 12-digit product number. When this number is scanned by the cashier at the check-out, it is transmis into computer which finds record associated with that item number in data base. The matching item record contains a description of the product, vendor name, price, quantity-on-hand, etc. The computer instantly does a "price lookup" and displays the price on the cash register. It also subtracts the quantity purchased from the quantity-on-hand. This entire transaction is done instantly. Shortly, a bar code represents ID data encoded in it, and that data is used by computer to look up all specific information associated with data. Now you may ask, but how does computer know what those bars and spaces are? Well, let's go to bar code scanning section.

What is a Bar Code reader or Bar Code scanner?

Computers can’t read bar codes. For a computer to make use of the information contained in the bar code, the bar code data must be captured and decoded into a data format that the computer can process. The device that reads or captures the bar code information and sends it to the decoder is known as the bar code reader, generally called bar code scanner.

How does bar code reader or bar code scanner works?

A typical Bar Code Reader kit consists of Scanner, Decoder, and Cable that interfaces the Decoder to the computer. The Scanner scans the Bar Code symbol and captures the bars and spaces of the bar code and sends it to the decoder. The decoder translates the bars and spaces into corresponding electrical output and transmits that data to the computer in a traditional data format. A bar code scanner can either have the Decoder built it, or be "undecoded". Undecoded bar code scanner requires a separate box called an interface or keyboard wedge.

What types of Bar Code readers are available?

Currently, the four different types of bar code readers are available: the pen type readers (bar code wands), laser bar code scanners, CCD (Charge Couple Devices) barcode readers and camera based barcode readers. Each of these types use a slightly different technology for reading and decoding bar code.

Pen Type Readers or Bar Code wands

Pen type barcode readers have a light source and a photo diode placed next to each other in the tip of a pen or wand. To read a bar code, you drag the tip of the pen across all the bars, in a steady even motion. The photo diode measures the intensity of the light reflected back from the light source and generates a waveform corresponding to the widths of the bars and spaces in the bar code. The barcode reader sends the waveform to the decoder, which decodes the waveform and sends it to the computer in a traditional data format.

Laser Barcode Scanners

Laser barcode scanners work the same way as pen type barcode readers. The only difference is that laser barcode scanner uses a laser beam as their light source, and uses, 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 bar code reader, a photo diode is used to measure the intensity of the light reflected back from the bar code.

CCD Barcode Scanners

CCD barcode scanners use an array of tiny light sensors lined up in a row, in the head of the barcode reader. Electric signal which fits line thickness and distance on bar code, is generated and sent in decoder, which decodes data and send them into computer. The main difference between a CCD barcode scanner, a pen type barcode scanner, and laser barcode scanner is that the CCD barcode scanner measures emitted surrounded light from the bar code, and not like pen type scanner, or laser barcode scanner, which are measeuring reflected light of specific frequency emiting, from the scanner itself.

Camera Based Barcode Readers

The camera based barcode readers use a small video camera to capture an image of a bar code. The barcode reader then uses sophisticated digital image processing techniques to decode the bar code.

How can I connect my Bar Code Scanner to my computer?

Bar code readers are coming in "keyboard port", USB or RS232 output. Bar code reader with keyboard output port plugs directly into the keyboard port on your computer and also provides a pigtail connector to plug in your keyboard simultaneously. When a bar code is scanned with the keyboard wedge bar code reader or on USB, the bar code data goes into the computer as well as it were typed on keyboard.

Advantages of the keyboard port and USB

Simple and easy connection to computer. No software is required.

Disadvantages of the keyboard wedge

When you scan a bar code, the cursor has to be in the correct input data field, and in the correct application, otherwise the bar code data will end up in any other  application that is active. This can cause all sorts of problems. The keyboard output is limited, within the meaning of that you cannot modify data in any way before you send them  in computer program. For example, if you need to separate a bar code message into multiple pieces or remove some of a bar code messages, you won“t be able to do that.

Advantages of Bar code reader with RS232 or "Serial Interface"

This type of bar code reader is connected to an available serial port on the back of your computer. When you read a bar code, you have control over how and where your data goes. You can perform any modifications on the bar code data before sending it to the computer or translating the data.

Disadvantages of Bar code reader with RS232 or "Serial Interface"

It is more complex than the keyboard port.

Which BarCode Scanner should I buy?

With all the choices available, it is important to understand your environment and applications, very well, before making decisions. Answer these questions to help you determine which scanner is best for you.
- What type of environment will the bar code scanner be used in? Harsh (as in factory or normal as in a store)
- What kind of scanning is needed?  Continuous or periodic?
- Is hands-free or hand-held capability required?
- Will scanning be conducted close to the bar code or from a distance?
- What will the bar code scanner connect to?
- Will scanned information be needed in real time?
Remember, there are a different type of bar code scanners suited for each application. The least expensive bar code scanner might work well in an application where scanning is infrequent, but it wouldn't work well in a harsh manufacturing environment where a rugged bar code scanner may be needed. Let us look at each of the different type and determine which one is the best for your needs.

Pen Type/Hand Held Wand BarCode Scanners

This is the easiest and cheapest  barcode scanner that is available. It is durable and contains no moving parts. However, when scanning, the it must come in contact with the bar code, which can present a challenge. Since the scanner must touch the bar code, if a bar code must be read more than once, it may become besmeared or damaged and, in essence, unreadable. Also, a scanner is "human powered," which means that it must be held at the proper angle and moved at the proper speed. For these reasons, a scanner is the best choice when money is the largest limit factor.

CCD BarCode Scanners

A CCD barcode scanner can read bar codes quick and easy,  but it has two primary limitations. First, it has a short "read" range, and must be held no more than 1 to 3 inches from the bar code. Further, the CCD has a limited width, and will not read bar codes that are wider than the face of the scanner. It is very popular for use in point of sale applications.

Laser BarCode Scanners

This is a very popular bar code scanner. A laser bar code scanner does not have to be close or in touch , to do its job. A standard range of laser bar code scanner, in which  can be read bar code, is about 6 to 24 inches away, and a long range scanner can read bar code from about 2 to 8 feet away. An extra long-range scanner can read a bar code 30 feet away, but in that case a minimal distance of reading is big.

Hands-Free or Fixed Mount Barcode Scanners

This type of scanner is fixed and user can scan bar codes using his both hands. Versatile, durable, and extremely reliable, high-throughput scanners, increases productivity to greater levels with minimal employee effort. This scanner is best choise for big retail objects, supermarkets and etc.

Wireless/Cordless Barcode Scanners

This scanner is for factory or warehouse applications where the cable/cord restricts movement. In a harsh environment where the cable can get damaged and make your scanner system inoperable, cordless scanner is the best solution. In shipping and receiving applications where the cable denies access, cordless scanner is the answer. In retail applications where a cabled scanner limits access beyond the counter area, cordless scanner is the solution. Cordless scanner is ideal for scanning heavy, oversized or solid items that are difficult to place on retail outlet.

Portable Data Terminals

This is a handheld battery operated bar code reader that stores data in memory for later uploading. In addition to a bar code scanner, a portable bar code reader has an LCD display and a keyboard. The user can walk around, scanning and entering data, and get a response from computer with each entry. Portable Palm Terminals combine Palm computer with integrated laser bar code scanner.

Wearable Barcode Scanners

This bar code scanner works  in two ways. A ring or hand Scanner is worn and activated by either pointing the finger at the bar code, while pressing the thumb against a trigger at the base of the finger, or by simply pointing the scanner at the bar code.

Bar Code Decoders

Bar code decoder is used to translate the bar code information into a data format that can be used by computer. Some bar code scanners can not decode bar codes (Un-decoded Scanners), therefore a decoder is required. Some users prefer to use the undecoded scanner with decoder unit so that they can remove the scanner for use with a portable terminal; some users does not like to switch scanners and decoder can make them problems.