How does a barcode work?
Actually, a barcode works in much the same way as an ordinary flashlight - by reading the reflected light from a surface. The process begins when a device directs a light beam through a barcode. The device contains a small sensory reading element. This sensor detects the light being reflected back from the barcode, and converts light energy into electrical energy. The result is an electrical signal that can be converted into data.
Barcodes are measured by the width of the narrow bar and are recorded in mils, or 1/1000 inch. A 15 Mill bar code, for instance, has a narrow bar that is 15/1000 inches wide. Further, "quiet zones," or blank spaces to the left and right of bar code symbols, are included to ensure the barcode can be read.
How do you read a barcode?
It's a three-step process. First, an input device must convert light energy into electrical energy. There are a variety of input devices, each with its own unique characteristics.
The "wand" is the simplest and least expensive input device available. It is durable and contains no moving parts. It must, however, come into contact with the barcode, which can present a challenge. If a barcode must be read more than once, it may become smeared or damaged and, in essence, unreadable. Also, a wand is "human powered," which means it must be held at the proper angle and moved at the proper speed. For these reasons, a wand is the best choice when cost is the largest determining factor.
The CCD, or "Charge Couple Device," is another common input device. A CCD is a very "aggressive" instrument, with a high ability to read barcodes quickly and easily. 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 barcode. Further, the CCD has a limited width, and will not read barcodes that are wider than the face of the input device. It is largely popular for use in point-of-sale applications.
The laser scanner is perhaps the most popular barcode input device. A laser scanner need not be close to the barcode to do its job. A standard range laser scanner can read a barcode from about 6 to 24 inches away, and a long range scanner can read one from perhaps 2 to 8 feet away. An extra long-range device can even read a barcode 30 feet from the device. Laser scanners vary in price from $200 to $2,000 and come in a variety of models.
Step two involves converting the electronic signal into data, which is accomplished with a decoder. The decoder is an electronic device serving three functions:
- It automatically discriminates between the various barcode types, which are known as symbologies.
- It decodes the electronic signal into information.
- It translates the information into data for the host.
A decoder may be located inside or outside the input device. An internal decoder takes up less space and is less expensive, but it is also less functional. An external decoder is a bit more expensive, but is also more functional, with the capabilities to manipulate data and accommodate multiple input devices on a single port.
Finally, barcodes are used to input data into a host computer system, and can dramatically improve both the accuracy of the data and the speed with which it is entered. The keyboard "wedge" is the most common method of host connectivity for barcode equipment. In this configuration, the decoder is "wedged" between the PC or terminal and its keyboard, allowing users to input barcode data without changing existing applications. The serial "wedge," which utilizes the connection of a dumb terminal with an RS-232 interface, is another connectivity method, and it is also possible to use a direct connection to a serial port.
Reading a bar code is as easy as 1-2-3
Step One: Carefully choose an input device
Step Two: Decide whether you need an internal or external decoder
Step Three: Attach equipment to the host computer
How do you print Barcode Labels?
Barcodes can be printed with existing dot matrix or laser printers, but with varying results. Thermal label printers, on the other hand, were designed specifically for the job and are built to produce high-quality text and graphics. They print at fast speeds and can be used to print one label at a time or an entire roll.
There are two basic thermal printing methods.
Thermal transfer printing
In this method, the print head transfers ink from a ribbon onto standard paper. The thermal transfer printer brings greater consumable costs because it utilizes a ribbon, but there is less wear and tear on the print head.
Thermal direct printing
In this method, the print head is in direct contact with treated paper, and no ribbon is used. As a result, consumable costs are smaller, but the print head undergoes substantially more wear and tear. A ribbon produces less friction than paper, so a print head lasts approximately four times longer when printing in thermal transfer mode than in thermal direct mode. Print heads are considered consumable items and must be included in the overall cost of operation.
Further, the width of the print head determines the maximum width of printed labels. Print heads are generally 2,4,6 or 8 inches wide.
Every thermal label printer is driven by a proprietary programming language, which can make the barcode printing process challenging. However, barcode label software can make it easier by allowing you to create labels on the screen and print labels with data from various sources. Label software can be generic to all printers or specific to one manufacturer.
What is a portable data terminal?
Sometimes you must bring the computer to the barcode, particularly to handle jobs, such as warehouse inventory control or freezer applications. A portable data terminal (PDT), a fully programmable hand-held computer, is necessary in such instances. Choosing the correct PDT is very important, and consists of a four-step process.
- Scanner Option - First, you must choose a scanner option. The barcode input device can be integrated into the unit or attached externally by a cable. The most common implementation is an integrated laser scanner.
- Display Unit - You should also choose a display unit. Character-based terminals use text to prompt the operator for data input, which can come from the barcode scanner or the keyboard. Some applications may require a graphical user interface, and a stylus (or pen) is used to operate the application software. These pen-based solutions are useful for filling in forms or applications that require signature capture.
- Communications - Collected data must be transferred back to the host computer from the PDT, which can be accomplished in one of two ways. A wireless communications link provides online real-time data communications, immediate updates to databases and feedback to the operator. However, this solution could require a complex connection to the host, and you may need a less difficult or expensive method. Mobile data collection is a simpler and easier process. In this method, data is collected in small batches and transferred from the portable into the host computer by a cable connection.
- Operating System - The operating system of the portable data computer determines the method of programming. Proprietary operating systems usually require knowledge of a proprietary programming language. Other units may use a common operating system, such as DOS or Microsoft Windows, allowing for programming with a more common language such as BASIC or "C." Most applications will be unique to the user and are likely to require customer programming. Programs may be written in a common language, or a program generator may be used to cut development time
To successfully sell portable data collection solutions, you should get to know your customer's business and look for applications that require mobile data collection. Remember these tips:
- Include barcode scanning and printing equipment in your total solution
- Don't forget the software
- Consider mobile data collection first and graduate to radio frequency communications later
- ScanSource is here to help you with implementation at any step in the process