Bar Code Basics

Contents

• What's in a Bar Code?
• Bar Code Structure
• Types of Bar Codes
• Bar Code Readers
• USB Readers
• Keyboard Wedge Readers
• Serial RS-232 Readers
• Portable Bar Code Readers
• Wireless RF Terminal Readers
• CCD Scanners
• Wand Scanners
• Slot Badge Scanners
• Laser Scanners
• Printing Bar Codes
• Bar Code Fonts
• Bar Code Applications
• Labeling Software

Introduction

This information is to help you understand bar codes so that you can better plan for your bar coding applications. The use of bar coding has been growing dramatically over the last 15 years. With the adoption of UPC as the standard for retail grocery stores in the late 70's, bar codes have become an everyday experience for most people. Bar codes are a fast, easy, and accurate data entry method. The correct use of bar codes can decrease employee time required and increase an organization's efficiency.

One thing to remember with bar codes: the application software that accepts the bar code data is in 95% control of the success or failure of an application. Bar codes are the sizzle on the software steak. You can eat steak without sizzle, but you can't eat sizzle without steak. Remember that bar codes are just another data input method; what you do with the data is most important. With the introduction of the IBM PC in the early 80's, bar coding applications expanded along with the PC explosion. Worth Data was and is a pioneer in providing bar code hardware and printing software to the PC (and Macintosh) user. Most of this booklet is devoted to bar coding in the microcomputer marketplace.

We hope this booklet proves of benefit to you in understanding bar codes and its associated technology. We wish you well in your undertakings and hope to be able to supply you with equipment and software to meet your needs.

What's in a bar code?

There is a mystique surrounding bar codes which intimidates many people. Let's eliminate it quickly. First the bar code usually doesn't contain descriptive data, (just like your social security number or car's license plate number doesn't have anything about your name or where you live). The data in a bar code is just a reference number which the computer uses to look up associated computer disk record(s) which contain descriptive data and other pertinent information.

For example, the bar codes found on food items at grocery stores don't contain the price or description of the food item; instead the bar code has a "product number" (12 digits) in it. When read by a bar code reader and transmitted to the computer, the computer finds the disk file item record(s) associated with that item number. In the disk file is the price, vendor name, quantity on-hand, description, etc. The computer does a "price lookup" by reading the bar code, and then it creates a register of the items and adds the price to the subtotal of the groceries purchased. (It also subtracts the quantity from the "on-hand" total.)

Another example of bar code data might be in a quality reporting application, the bar code may have only a single digit in it, but it may be titled "Failed Vibration Test". The computer associates the single digit with the test result.

So, bar codes typically have only ID data in them; the ID data is used by the computer to look up all the pertinent detailed data associated with the ID data.

Bar Code Structure

A bar code is a series of varying width vertical lines (called bars) and spaces. Bars and spaces together are named "elements". There are different combinations of the bars and spaces which represent different characters.

When a bar code scanner is passed over the bar code, the light source from the scanner is absorbed by the dark bars and not reflected, but it is reflected by the light spaces. A photocell detector in the scanner receives the reflected light and converts the light into an electrical signal.

As the wand is passed over the bar code, the scanner creates a low electrical signal for the spaces (reflected light) and a high electrical signal for the bars (nothing is reflected); the duration of the electrical signal determines wide vs. narrow elements. This signal can be "decoded" by the bar code reader's decoder into the characters that the bar code represents. The decoded data is then passed to the computer in a traditional data format.

Types of Bar Codes

Many were invented some time ago and have been superseded by newer bar codes. Some industries standardized on older bar codes before the better ones had been invented, thus there is a continuing requirement for their use in particular industries.

Many readers have to comply with their customer's or industry's bar coding specifications; no choice is possible, just compliance. Look at the following samples of printed bar codes:
 

The classic bar code type is Code 39, (also called Code 3 of 9) which has 9 bars and spaces; three are wide, and the other 6 are narrow. In Code 39, 3 of 9 total bars and spaces are wide; hence the name, Code 3 of 9. For example, look at the following character representations with Code 39:
 

Notice there are two widths of bars and two widths of spaces. If you wished to print a bar code of ABCD, you would need to start and end it with a special Start/Stop code character - the * (asterisk) is used for Code 39. So to print a bar code of ABCD, it would need to be printed as *ABCD*. There should be at least 1/4" of white space to the left and right of the code; this helps the reader pick out where a bar code begins and ends.
 

Other bar code types are similarly constructed. UPC and EAN bar codes have four widths of bars and spaces; so does Code 128.

Bar Code Selection Recommendations

The larger the width of the elements, the more space it takes to print the bar code; therefore, the lower the bar code density. The thinner the bar and spaces, the less space is required and the higher the bar code density. Look at the samples below of different densities:

Lower density bar codes are more reliably printed and more consistently read than higher density bar codes, because minor variations (due to printing or damage) are much more serious with high density bar codes - the percentage of distortion is larger.

Bar Code Readers

USB Interface Bar Code Readers

A more recent interface available for bar code reading is the Universal Serial Bus interface. Most new PC’s (with Windows 98, ME, 2000, and XP only – neither Windows 95 nor NT offers USB support) and Macs come with several USB ports available for peripheral attachment. Data transmitted by the bar code reader to the USB port appears much like data coming from a keyboard wedge reader; in fact, USB interface can be used to input data into the same applications that would typically be used with a keyboard wedge reader.

Worth Data now offers integrated USB interface on all our keyboard wedge readers; both integrated scanner models (LI50-WDP, LZ110-WDP and LZ210-WDP) as well as those using a separate decoder (P22 WDP). Worth Data also developed a USB interface adapter that allows an existing keyboard wedge reader to attach to the USB port. The Wedge Saver™ helps the user avoid buying new readers simply for USB interface (some new PC’s don’t have keyboard ports; they only have USB).

Our TriCoder Portable reader now also features a built-in USB port. Keyboard input as well as lighting-fast USB uploading (40 times faster than through the serial port) is supported.

Personal Computer Keyboard Wedge Readers

If the bar code reader is attached through the keyboard interface, the bar code reader sends data in key codes, exactly as though the data had been keyed on the keyboard. Keyboard interface readers are nicknamed "wedge readers", because they physically wedge between the keyboard and the computer (or mainframe terminal) and attach as a 2nd keyboard. The great advantage of "wedge readers" is that bar code reading can be added with no software changes necessary; the software thinks that the data received was produced by a fast typist. (Of course the keyboard remains usable too!). With a wedge reader, any program that accepts keyed data will accept bar code data with no change. The following figure shows a keyboard wedge reader attachment.

A keyboard wedge reader which emulates all of the keys including function keys, Ctrl, Alt, Page Up, etc. is preferable. You cannot place a keyboard wedge reader more than 10 feet from the computer.

You cannot place a keyboard wedge reader more than 10 feet from the computer. You can get an extension cable for the scanner, allowing you to range up to 35-100 feet from the computer. For these applications a cordless radio frequency scanner would be better; the scanner has a transmitter and the decoder has a receiver so that the scanner can transmit digitized data to the decoder over RF instead of a cord. RF readers transmit up to 150 feet.

Serial Bar Code Readers

Another method of data transmission from the bar code reader to the computer is by RS-232 Serial ASCII format. If you have a multi-user computer, (for example a UNIX system), with serial ASCII terminals for each user, the bar code reader can attach between the terminal and host computer, transmitting ASCII data just like the terminal; in fact the bar code data looks just like keyed data. when attached like the following figure:
 

Single user computers without an external keyboard (most notebooks) must use the serial port for interface of a bar code reader; to get the bar code data to appear as keyed data, a TSR or device driver program is also necessary. Typically requiring only 2K of RAM memory, the program takes data from the COM port and places it into the keyboard data buffer, so bar code data appears to have been keyed. If your computer program can read a serial port directly, no additional program is necessary.

. Also, when adding a serial reader to a laptop, notebook or palmtop, it is important to use a reader that does not draw power from the computer itself. Worth Data has designed a serial interface laser scanner that is battery operated, saving all of the laptop or notebooks’ battery power for the operation of the laptop or notebook computer itself.

Serial readers can be placed several hundred feet from the computer, (keyboard wedge readers cannot be placed beyond 10 feet.). Also multiple serial readers can be attached to the same computer, (keyboard wedge readers cannot). The PC runs a program to poll the readers one at a time, thus avoiding the "mish-mash" of data from multiple readers.

Portable Readers
Portable readers are handheld battery operated readers which store the data in memory for later uploading. In addition to a bar code scanner, a portable reader usually has an LCD display to prompt the user what to do; and they usually have a keyboard to enter variable data such as quantities. Ease of programmability is a key issue in selecting a portable, and that depends on your programming abilities; lots of vendors say it's easy, (as long as you can program in C++ or go to their two week school). Other variables to consider are: battery life (at least 20,000 scans), ease of reading the display, size/weight of the unit, who repairs it, and where it is to be repaired in the event of a malfunction.

Worth Data has pioneered and patented voice prompt messages to supplement the display messages in a portable unit, overcoming lighting, language, and message clarity problems; this unit actually announces when you have entered incorrect data and when to change the batteries or upload data, plus you can customize any or all voice prompts for your applications.

Most of you will want a unit that requires no programming for inventory - a unit that has built-in inventory data collection programs - on which you can easily create custom programs.

Radio Frequency Readers

Radio frequency readers are the ultimate solution to many applications' needs - especially any computer remote application that can benefit from the computer checking and instructing the operator. Warehousing applications such as picking, put-aways, shipping, and receiving are typically better performed by RF readers because the computer can instruct the operator where to go and what to do, plus the computer files are current as to exact status and location of available inventory.

RF Readers are like on-line terminals, but wireless. The user can roam around his local facility scanning and keying data and getting a response from the computer with each entry. Therefore the computer can very carefully edit the data for errors as well as prompt the user for what to do next considering the data that has just been entered. The classic RF applications and associated advantages are:

• Picking - routing of the picker; computer instructed substitutions; real-time status of the order.
• Put-Aways - inventory is available for sale or for manufacturing immediately.
• Receiving - purchase order shortages can be immediately determined. Critical parts can be routed to manufacturing immediately.
• Shipping - eliminating wrong or incomplete shipments by computer checking before loading or even computer led loading.

There are two basic types of RF Readers on the market:

• Readers that emulate terminals or PCs, and
• Simpler Readers which talk to a computers serial port. A brief explanation follows:

RF Readers that Emulate Terminals
These readers started out as mainframe terminal emulators such as IBM 3270 or 5250 terminal emulation. To emulate an IBM mainframe terminal is no easy task, so the cost was very high, (i.e. $10,000 per control unit, $4000 per terminal).

Today there are several emerging terminals that emulate PC workstations (i.e., Symbol Technologies and Intermec) on NT or Netware Local Area Networks. These machines are 486 computers with lots of memory and download their software from the network server. They are relatively expensive, about $3000-$5000 per terminal, require an operating LAN, mostly require applications to be written to the upper left hand corner of the screen, and usually require a network controller that is $3k-$10k in cost. These terminals almost always require a C++ program to be written on the terminal and the host programs to be modified to just use the upper left hand corner of the screen. Competent network management personnel are also required for each location.

RF Readers that Talk to a Serial Port
These readers require programming on the host computer to read and write to a serial port. Such programming is relatively trivial and can be written in almost any language or any platform. Existing application packages can be modified to include these simple RF readers, but programming is required. It could be argued that the amount of effort is considerably less than with terminal emulation, because all programming is on the host computer; the terminal emulation programs require host programming (for the upper left hand corner) and programming on the terminal too.

Readers that communicate to the host by serial port are usually less than 1/2 the price of the more complicated "Terminal Emulators"; they also often have faster response time due to less software overhead. No network is required - even a slow 286 can drive them at maximum speed. They are far simpler - thus less costly, BUT they do require programming to get their full potential. Even though you can run them in "One-Way" mode without programming, that misses the greatest potential of computer-led activities, (often referred to Event Driven Applications).

Spread Spectrum Terminals vs. Narrow Band Terminals
Narrow band refers to radios that operate within a narrow band of radio frequencies. Spread spectrum refers to radios that jump around on a wide band of frequencies to avoid interference. Narrow band can be licensed at high power and unlicensed at low power. Spread spectrum is almost always unlicensed at high power. Spread spectrum is superior for very large networks of RF terminals - 150 plus terminals in the same building. For terminal networks below that number, unlicensed narrow band is usually less expensive, far less difficult to program and it usually transmits just as far with considerably less power and battery size/weight.

Narrow band radios with a user changeable frequency has the same advantage as spread spectrum in avoiding interference. In fact, it can be argued that 10 plus channels of user selectability are at least as safe as spread spectrum with a fixed pattern. What you really want to avoid is narrow band terminals with a fixed frequency that cannot be changed unless sent back to the manufacturer. More and more devices are going wireless; so, the channel interference is expected to increase substantially in the future.

Worth Data's R/F Terminal
We offer a narrow band radio that has 16 user selectable frequencies, thus avoiding interference with other devices that might operate in the same band. Because its receiver is so sensitive, the coverage is outstanding- typically 500,000 square feet without relays and up to 3,000,000 square feet with relays. Each base station can handle 300 transactions per minute.

The cost is 1/2 of most Spread Spectrum systems. All programming is on the host computer using any platform and language that can read/write to the host's serial port. Using multiple base stations with split traffic, the number of terminals per site can easily go up to the 50-100 per site. Models are available for the US (911MHz), Europe (434MHz), Australia/New Zealand (921MHz) and Korea (424 MHz).

Scanners

CCD Scanners

CCD scanners are a "can't miss" scanner too. Most have to be placed on the code for reading but some offer "laser-like" distance reading. Some are trigger-less and some require the trigger or button to be pushed to initiate reading. CCD scanners scan around 50 times per second; so unsuccessful read attempts go unnoticed.

Traditional CCD scanners have a "depth of field", (how far you can be away from the bar code and still get a read), of only ½". They have to be placed on the code to get a read. Just recently, CCD scanners have been developed with a depth of field previously only achieved by laser scanners. These CCD scanners are so unique that they have been termed "Linear Imager" scanners.

With Laser scanners and CCD scanners now sharing the same range, it is important to know the difference between them. Laser scanners use a single spot of light that sweeps across the bar code in a linear fashion. In a sense, lasers act like a wand, transmitting the signal for each bar and space as it "scans" across. This "scanned" pattern is then decoded. A CCD scanner on the other hand, uses an LED array with thousands of CCD light detectors for the reflected light. The entire bar code "image" is captured and then the array elements are transmitted to form a signal pattern identical to the "scanned" pattern from a wand or laser. There are no moving parts in a CCD scanner.

We offer the LI50 CCD as both a scanner (for attachment to a decoder) and an integrated keyboard wedge reader. The LI50 can read a typical UPC code from up to 7.5" away. Traditional CCD Scanners have a front opening, typically 2 inches or 3 inches - if you suddenly need to read a larger bar code than the width of the CCD scanner front opening, it can't be done. The LI50 can read a medium density bar code up to 4.5" in length (possibly longer if low density).

Scanner Comparisons

Integrated Readers

Most bar code readers have separate decoders, but decoders can also be integrated into the scanner, usually the handle. An integrated reader is usually less expensive and saves the space of the separate decoder. The disadvantages of integrated readers are: 1) you can't have a 2nd scanner such as an inexpensive wand for backup to a laser or CCD, and 2) power supplies cannot be added for low power keyboard ports.
 

Laser Scanners

Laser scanners have a very precise beam of light which can be reflected accurately several inches to several feet. Almost all laser scanners today have a moving beam which sweeps back and forth, (some older laser scanners required the user to move the beam across the bar code). The advantages of moving beam laser scanners are:

• Reading bar codes from a distance (typically 3-18 inches, or up to 17 feet with reading low density bar codes).
• Reading moving objects on an assembly line.
• No-hands operation. Some lasers can be mounted to turn on automatically when an object passes under the scanner. Typically used in blood banks, library check out, etc.
• Reading through glass windows or thick laminates.
• Reading bar codes on curved surfaces, (bags of parts).
• Reading bar codes inside difficult to reach enclosures.

Laser scanners emit a laser light beam which sweeps back and forth across the bar code 36 times per second. At this rate, unsuccessful reading attempts go unnoticed; you will only be aware of the one successful decode. Once a read has occurred, the laser turns off, requiring you to release and pull the trigger again to reactivate the laser scanner.

The lower the density of the bar code, the further the laser scanner can read a bar code. The higher the density of the bar code, the closer to the bar code the laser scanner must be.

Triggered Laser Scanners
Triggered Laser Scanners are virtually "can't miss". Just "point and shoot". Face the bar code so that the bars point up (the laser light will then form a red line across the bar code when the trigger is pulled). Aim the gun scanner at a bar code and pull the trigger; reading is instantaneous. You may have to move the scanner closer to the bar code to get a read, but that's it. Triggered laser scanners are about 5-10 times more expensive than a wand scanner, but scanning is significantly easier. Pay attention to the length of the warranty on laser scanners; it could prove to be very important with heavy usage.

To the left is pictured the Worth Data LZ200 Laser Scanner, which has a 3 year warranty, the industry's longest. (It reads from 20 inches from a typical medium density bar code). The basic laser scanners read up to 10-20" distance, depending on the brand of the laser scanner. There are hand held triggered long range laser scanners that can read up to 33 feet distance, (using retro-reflective low density bar codes) or 10 feet distance using paper low density bar codes. Long range laser scanners are naturally more expensive than the standard laser scanners.

We have tested the Worth Data LZ100 and the LZ200 by hard throwing (not just dropping) them to the floor. They survived every repeated throw. The scan element has a lifetime warranty; both scanners use models of the Symbol 1200 Scan Engine, (this engine is rated to withstand 2000G's of force on impact). We developed this laser scanner after years of frustration with other laser manufacturers' product reliability. Symbol lasers had superior reliability to anything else we sold, but they were difficult to integrate with our readers unique feature offerings. Therefore, we were forced to manufacture our own laser scanners using Symbol engines. Being the manufacturer, we can more closely control function and reliability.

Supermarket Slot Scanners
These devices are continuously emitting multi-directional light beams to maximize the reading of a bar code regardless of the orientation of the bar code to the scanner. Unless the bar code is on the surface of the item pointing straight up, the bar code reader has a good chance of reading it. These devices are required to be integrated into the sales counter. They typically directly interface with a retail POS terminal.

On Counter Scanners
These devices are the smaller cousins of the Supermarket Slot Scanner. They were developed for the convenience stores that wanted automation but didn't have the counter space required for a slot scanner installation. They also have a omnidirectional light source to free the user to present the bar code in any orientation. They sit on a counter, or they sit on a stand that sits on the counter. Items are passed a few inches in front of the scanner to get a successful read.

Industrial Scanners
There are also a whole line of scanners made just for industrial applications including small under $1000 scanners that read a few inches distance and large $20,000 long range scanners that read twenty feet away. These are typically mounted adjacent to conveyor lines to read bar codes on passing items; the host computer then directs the items to the appropriate branching line. A classic example of such scanners use is airport baggage sortation; (those bar codes that are placed on your luggage are actually used in the large airports to get your luggage to the right place -except Denver). This type of equipment is almost always sold with turnkey hardware (including conveyors) and software by specialty integrators. Sources for industrial laser scanners are:

Wand Scanners

Wand Scanners are the least expensive and the oldest type of bar code scanner. A wand is typically made from 1/2" stainless steel tubing or from plastic; optics are in the front with a cord out the back. The wand scanner must be moved by the user's hand across and in contact with the bar code. While the wand is moving across the bar code, the reflected light is converted to electrical signals through a photocell in the wand.

A wand requires a little technique; it is not a "can't miss" scanner. Even without directions, most people can master the use of a wand in 30-45 seconds; but some need directions and training for a few minutes to learn the proper wanding techniques.

Wands can read any length of bar code. Wands typically can read through laminates of thickness up to 1/10" inch. Many wands can read through CD cases and audiocassette cases.

Slot Badge Scanners

Slot badge scanners require only one hand for operation; the user simply slides his badge with a bar code on the bottom edge through the scanner. These are typically used in unattended entry/exit stations for payroll, club membership accounting, school lunch assistance programs, etc. Slot badge scanners are similar to wand scanners, but usually refined so that one resolution can read most types of bar codes with no difficulty; utilizing the additional space for larger optics, a slot badge scanner usually has a vertical aperture to look at the elements, thus allowing a high resolution slot badge scanner to read almost all types of printed bar codes, from dot matrix to high density.

Slot badge scanners also come with visible or infrared light sources. Visible can read any bar code which can be seen with the eye including bar codes printed on thermal printers, (infrared cannot read thermal printed bar codes); infrared slot badge scanners would be used for security "black on black" bar codes, (the black bar code is covered by a black window on the badge, but the black window looks clear under infrared light).

Cordless Scanners

There are at least four RF Scanners available on the market. These units have decoder, battery, and transmitter built into the scanner -- allowing cordless scanning back to a base station/decoder. Their range varies from 20-30 feet from the base station.

Below is pictured the Worth Data R/F Laser Scanner. It has a range of 100 feet. It reads 0-18" away from the bar code. Competitive RF Laser Scanners cost considerably more. The two-way laser version has a "good read" indicator as well as a confirmation "base received data" beeper in the laser scanner, so you don't have to be near the base station to hear a "good read" received. The Base Station connects to a PC or Mac in series with the keyboard or it connects to a serial port. Multiple 2-way laser scanners per base station are possible.

Worth Data also offers two wireless CCD products - the LI101-RF 1-Way RF CCD Scanner and the LI102-RF 2-Way RF CCD Scanner. Both work in the same fashion as their 1-Way and 2-Way Laser relatives in terms of RF communication, but have a read distance of up to 11" instead of the lasers 18". The LI101-RF and LI102-RF are considerably less expensive than the RF Lasers. .

Printing Bar Codes

• Buying photocomposed bar codes from a label manufacturer.
• Printing your bar codes with inexpensive labeling software on your personal computer's dot matrix, laser, or inkjet printer.
• Printing bar codes on a specialized bar code label printer.
• For manufacturers who need bar codes printed in their product's packaging, use purchased film masters or use bar code fonts suitable for PostScript® film output.

Whatever printing source you decide upon, there are a few common sense tips to pass on:

• Stay away from colored bar codes (use black) and colored backgrounds (use white). Any other colors lower the contrast between bars and spaces and therefore lower readability.
• Do thorough readability testing on any labels before distribution. Be careful. Don't discover a problem after you have distributed 10,000 labels that need to be recalled.

Pre-printed Labels
If the only bar code application you are doing is an application such as fixed asset inventory tracking and employee badges, pre-printed serialized labels make a lot of sense. Photocomposed labels are usually very high quality and you can buy 5000 for around $300. Libraries typically use pre-printed labels. Why? Because the labels need to last for 25 years and the volume is usually 100,000 per library. High quality, durable, laminated photocomposed labels are usually used. Companies like Data 2 (800-227-2121) supply such labels.

(You can also print high quality durable labels on a thermal transfer printer using XT Polyester label stock or on a laser printer with a poly label stock (call Worth Data for our Worth Poly™ Polyester Laser Label stock); such stock is more expensive than paper. ).

Printing on PC Printers
With the proper PC software, today’s printers are capable of printing excellent quality bar codes. Ink Jet and Dot Matrix printers cannot print high- density bar codes, but laser printers can. Laser printers actually print the best quality bar codes of any commonly available printing technology.

Laser Printing
Laser printers can produce outstanding quality bar codes. The quality is consistent even when toner gets low; it is obvious and is not subject to interpretation. (When the toner cartridge is changed, it is important to follow the replacement cleaning instructions, including cleaning the corona wire, especially for high density bar code printing.)

Labels are sectionalized on a 8 1/2" x 11" page in multiple columns and/or rows. For example, mailing labels (1" by 2.8") appear in 3 columns and 11 rows, 33 labels per page. Since laser printers feed one sheet at a time, it is impractical to print one label at a time.

There is an unprintable area 1/4" inch to the left, right, top, and bottom of any form; this makes full labels impossible unless you sacrifice the top row and maybe the bottom row of labels. One trick in laser printing is to use label stock with the laser's unprintable areas cut as a border picture frame around the printable label's area. For example, the previous example of 33 mailing labels per page would be 30 labels per page with the unprintable area isolated as a picture frame border. The top and left margin settings in the program would adjust the labeling program to the picture frame label stock's unprintable borders.

Laser printers are great for producing batches of labels, but if you need only one label (where there are multiple labels per page) at a time, dot matrix or thermal transfer printers are required. Laser printing is the best quality of all types.

There are several types of label stock available for laser printers. If you need to print durable labels, Worth Data offers a polyester label stock designed especially for laser printers. Worth Poly ™ is made from a special white, matte finish, heat stabilized polyester film designed for laser printers. When printed on a laser printer, the resulting label is heat resistant, water-resistant, light resistant, scuff resistant, smudge resistant, and stain resistant. These labels are ideal for any labels that you want to last through rough handling, repeated usage, outdoor usage, or other harsh environments. The permanent adhesive is designed to keep your label adhered to wood, metal, plastic, or glass for years. You pay a little more, but you get a lot more label for the money.

Windows programs usually give you rich text fonts, more rotations, and excellent image graphics printing. The labeling programs for Windows often support Postscript printers.

Ink Jet Printers
These printers are getting better and better. They print pages of labels, so refer to the page label stock discussion below regarding page laser label stock. Also, use label stock specifically meant for inkjet printers – the stock is usually coated to minimize ink bleed. Always test your bar code labels for readability before printing in bulk.

Inkjet printers are almost exclusively supported by Windows programs. If you have problems, check to make sure you are using the latest driver version from the printer manufacturer. Also, be sure to select a printer that has a separate black cartridge in addition to the color cartridge.

If labels you are printing are going to be exposed to water, don't use the inkjet printers – most inkjet ink is water-soluble. Inkjet printers are NOT the best printer to use to print labels that need to withstand the weather or are subjected to constant scanning.

Beware; the inkjet cost per page in color is twice cost of a black and white print.

Thermal Transfer Printing
Thermal transfer printers are required when you need either to print one label at a time or when you need to print a roll of labels so that labels can be applied by applicators directly to boxes. Volume industrial printing in the 90's is done mostly by thermal transfer printers. They are fast and produce excellent quality bar codes.

Thermal transfer refers to the printhead heating up and melting a ribbon onto the label surface. Most thermal transfer printers can also produce "direct thermal" labels, but paper instead of a soft ribbon wears out the printhead 10 times faster; another disadvantage of thermal printing is that most thermal labels cannot be read with IR light and deteriorate in sunlight to non-readability over time. The media cost is about the same as laser and direct thermal. Therefore thermal transfer printing is far more popular than thermal printing for serious label production.

Beware of the CoStar and Seiko thermal printers for producing serious bar codes. They have two problems:

• The bar codes are just a little off. (The naked eye can often see three sizes of bars when only two are supposed to be possible).
• They are thermal printers producing bar code labels that will deteriorate to unreadability in sunlight.
• They are inexpensive, so they are very attractive, but beware.

Most popular thermal transfer printers can produce labels up to about 4" wide (more expensive models can print at 6" or even 8") and lengths up to 8 inches plus. Smaller widths can of course be accommodated. Popular thermal transfer printers are manufactured by Citizen, Sato, Zebra, and Datamax; these are the major brands.

You can get almost any type of label stock imaginable for thermal transfer printers; high temperature, weather proof, surface laminated, jewelry ring stock, card stock, tag stock, etc.

The basic paper labels with inexpensive ribbons produce bar codes that can be smeared or smudged with hard rubbing by the fingers. Smudge proof labels can be produced with more expensive synthetic label stock and a ribbon with less wax and more resin (hybrid or P2 Ribbon). Scratch- proof laminated labels can be produced with XT Polyester and a high resin ribbon; when heated, the resin and polyester coating fuse to make a very durable label. Worth Data has a variety of paper, synthetic and polyester labels stocks and ribbons to choose from.

These printers generally print from 2" to 12" per second; at any width up to the maximum, the printers print 2" to 12" lengths per second. Find out if the rated speed quoted for the printer you are considering is to be expected when printing bar codes or graphics - for this, many printers slow down to less than 1/2 their quoted speed.

The print heads wear out on thermal or thermal transfer printers. To maximize the print head life, clean it between every ribbon change with a cleaning card or with a lint-free q-tip soaked in alcohol -a MUST to avoid continually replacing printheads. Unlike most dot matrix and laser printers, the thermal transfer printers discussed have scalable text fonts and bar code fonts resident in the printers firmware. The software necessary to print the bar codes is a series of special command sequences. So you can add printing on a thermal transfer printer to one of your existing programs, providing there is someone semi-skilled at programming.

However, most users want a general purpose design labeling program which requires no programming. It helps to buy the printer from the developer of the labeling software so that you have a single party who has an interest in keeping the software bug-free and matching the printers capabilities that you want.

Dot Matrix Printing
Dot matrix printers can produce good quality low volume bar code labels. When printing low-medium (3.7cpi or lower for Code 39), the labels can be excellent quality. The Epson, IBM, and Okidata printers have adequate graphics capability to yield good quality bar codes. You will need a dot matrix printer with a pin feed platen to successfully print the variety of label sizes.

There's one catch though - you must not wait too long to change the ribbon. The printer operator must make a judgment call on when to change the ribbon. It's best to tape a bar code of minimum acceptable darkness on the printer, so the operator can't make a judgment error. Programs that can strike the bar codes multiple times can keep the ribbon expense down.

Both 24-pin and 9-pin printers can produce good quality bar codes. The 24- pin printers produce better bar codes than 9-pin printers, especially as the ribbon is getting low on ink. The 24-pins simply put more ink on the paper.

Labeling Software

Because dot matrix, Inkjet and Laser printers are in such widespread use, labeling software to make these printers capable of printing bar codes has become readily available. There are two general types of bar code printing programs available:

• Menu-driven programs for operators to design and print labels.
• Bar code font programs to allow printing of bar codes within other Macintosh or Windows programs; no programming is necessary by the user.

Stand-Alone Menu-Driven Programs
These programs allow the user to design different label formats and save them to disk for label runs. Usually there is a WYSIWYG design interface to view the label on screen as it is being designed, especially Windows programs. These programs usually have most of the following features: scalable fonts, graphic image import, all popular bar codes, data file import, easy custom operator interface, popular data base access, and/or built-in label data base. Look for a program that doesn't combine support for laser/dot matrix with thermal transfer. Separate programs for common PC desktop printers vs. thermal transfer printers keep it simple for the user.

Besides the ability to design and print labels, you should look for a program with a simple operator interface. The label designer creates custom prompts for a label format; then the operator answers simple questions that lead him to enter the variable data for the labels to be printed. With a label database, you can select which labels to print. You don't want the operator to have to deal with the more complicated label design screens.

Font Programs
In Windows and Macintosh environments, any font based program can select fonts for printing. This makes it possible to use bar code fonts from such programs (i.e. Word, Excel, PageMaker, Quark, etc.). Problems which must be overcome are:

• Scaling - when scaling, Windows and the Mac can make little adjustments that really mess up the bar codes; most programs give you fonts at a certain point size and density that will be very accurate for the point size and printer for which they were designed; however if you change printers or change point sizes, almost anything can happen. Be careful when straying outside the standard point size, printer specific fonts
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• When printing UPC, an "0" could be represented by four different bar/space patterns, depending on where it is in the code and the computed parity of the data. Therefore it is necessary to have a translator program which you can switch to, enter the data you wish to print, copy it to the clipboard, and then copy the translated strings into your application. At least one program has a "hot-key" sequence which can copy the bar code into your application without having to first translate and then copy from the clipboard; after setting the bar code type and density from the translator, any highlighted data in the application is translated with the "hot key".

Using fonts, labels can be printed from your favorite word processing program, or you can add bar codes to a form from almost any font-based Windows program, (provided your program can call our DLL).

Bar Codes on Packaging or Film Masters
How to Get a UPC Number
If you haven't already been assigned your manufacturer's number by the Uniform Code Council or appropriate EAN authority, call (UCC is 937-435-3870) to get registered. You will pay a charge to get a manufacturer's number assigned, (digits 2-6 in the UPC code), plus you will get an information packet. You can create up to 99999 unique UPC numbers for all your products.

For users who wish to have the bar codes printing as an integral part of their packaging (such as sugar bag) there are three ways:

• Create your packaging design with a Windows or Mac based program and use a postscript bar code fonts package to add the bar codes to the whole packaging design. The film for the packaging would include the bar code.
• Order separate film masters from organizations that specialize in bar code film masters (such as Symbology Inc. 1-800-328-2612 or www.symbology.com). Have your printer strip in the bar code film to the packaging film so that the whole packaging prints with the bar code included.
• A third method that must be done with caution is to print bar codes on paper with a good bar code printing program, photograph the printed bar code, and then use the film as specified above.

After printing, the ink in bars tends to bleed slightly into the spaces. Therefore, bars on film should be slightly narrower, (probably 1/1000 inch narrower), to allow for the spreading or the ink in printing. (Turn down the darkness on the laser printer if printing bar codes on paper to be photographed.)

Whatever method you use, you should have your printer make test print runs. If you don't use a verifier to test the accuracy of the bar codes, at least:

• Test them with a bar code reader for readability. You should get 20 out of 20 reads with reasonable attention in wanding. Don't accept any bar code that has less than 100% readability. AND
• Have your printer (the person doing the printing) microscopically inspect the narrowest bar and narrowest space after printing (wait about 30 minutes to 1 hour for any bleeding of the ink to complete). They should be very close to equal. If they vary by more than 10% from each other, then the exposure on the film must be changed; if the bars are too big, expose less; if the spaces are too big, increase the exposure.

Don't forget to leave a 1/4" white space to the left of the leftmost bar and a 1/4" white space to the right of the rightmost bar, (no text or other graphics in these areas).

Bar Code Applications

Data Capture Applications
Assembly Checking - usually done with custom assemblies, a terminal leads the operator in what to assemble; as the operator scans each part or subassembly added, the computer can monitor for correct specifications.

Fixed Asset Inventory Control - large organizations have multitudes of furniture, PC's, fixtures, etc. The exact location for each item determines cost allocations. Bar codes are placed on all items and bar codes are placed on walls of each location. With a portable bar code reader, the location is wanded and then all items in that location are wanded; the data is then uploaded to the computer for accurate depreciation cost allocation.

Job Costing and Tracking - as item(s) are completed, scanning results into a terminal. (Multiple operators use a single terminal).

Labor Distribution - again using employee badges, as employees move from department to another, the employee scans in his badge at the new department's terminal. This allows payroll cost allocation to departments..

Library Automation - bar codes on ID cards of patrons and bar codes on books. Automatic check out.

Meter Reading - similar to a pick list, but downloading to portable terminal the list of addresses to be read, along with the bar code ID of the meter, so that the terminal checks that the operator is indeed reading the right meter.

Order Books - catalogs of items with associated bar codes. Used for order taking, estimating car repair costs, route accounting, etc.

Point of Sale - at the cash register (or equivalent), scanning the bar code into a computer which looks up the item scanned and displays the description and price plus decreasing the on-hand inventory by the quantity purchased.

Records Management - for patient records, case records, loan records, etc., a bar code is placed on the folder. Then as the units are checked out, the folder is scanned and the borrower's ID card is scanned. As the unit is passed from one station to another, the item is scanned so that it can be tracked through the organization.

Remittance Processing - printing a bar code on the remittance stub or the invoice stub so that when the customer returns the stub with his payment, it can be wanded to bring up the data or to complete full payments.

Stock Taking - the classic portable bar code reader application. The operator scans the codes of the items (perhaps scanning only one of multiple items and then entering the quantity for that item) and then uploading the stored scanned data to the computer later, thereby correcting the computer's files for what is actually on the floor.

Time and Attendance - employee badges with bar codes are read at clock-in and clock-out into a computer or terminal to provide attendance data to the computerized payroll program.

Warehouse Picking - the computer downloads a table to a portable terminal and the operator is prompted to pick a list of items associated with a specific order. After picking the order, the operator goes back to the terminal to upload the data and receive his next order to pick. As locations are reached or items are picked, the bar codes are scanned and the terminal compares what was scanned to be sure the right location or item is being picked.

Warehouse Put-Aways - as the operator stores items in a warehouse, the operator scans the items and the location. This data is the uploaded to the computer so it can keep track of the inventory quantity on hand and locations.

Warranty and Service Tracking- as units are received, the bar code on the case of the unit is scanned, bringing up the computer history for that unit. As the unit is repaired, scanning what failures and what new parts are required to repair for costing and failure analysis.

Work-In-Process Inventory Tracking - with on-line readers or portable readers, scanning the routing sheets with bar codes on them as parts or subassemblies are completed, often including yield data, so the work-in-process costs and progress can be tracked. (Usually one terminal per operator).

Event Time Applications
There is now a variety of hand held bar code terminals which are linked by Radio Frequency (RF) back to a host computer. This makes possible portable interactive applications in the stock room, the warehouse, shipping, receiving, etc.

Whatever the cost of the hardware, the application software investment is intense for most companies. It is really an extension of MRP II software into the portable hand held terminals.

Applications include:

Rental Car Check in and Billing - Anyone who has rented a car lately has experienced the convenience and speed of RF Terminal check-in at the curb.

Massive Table Lookup - The simplest application is the computer performing validity checks on data entered from its large up-to-date computer files and notifying the operator of any invalid data.

A classic example of this would be grocery price validation. Instead of downloading a 10 MB file into a hand held, the computer does the table lookup and lets the operator know what prices need to be changed on the floor. Any store without prices on the items must have price validation by RF Terminal to be sure the prices on the floor are the same as the price in the computer. Direct Store Delivery by vendors is also a must for RF Terminals, allowing the store to monitor the price being charged by the delivery personnel to the store.

The best example is stock taking. Based on the outage or overage, the computer would instruct the operator in different things to do: count again, see supervisor, etc. The counts could be double checked on the spot, yielding a faster more accurate inventory count.

Receiving - As a purchase order is received, the operator scans and keys what has been received, with the computer pointing out shortages that are double checked on the spot rather than after the items have been moved or partially used.

Shipping - As items are loaded, they are scanned. Shortages or misloads can be detected immediately.

Put-Aways - As items are put away, the computer has them immediately available for picking to satisfy the next order.

Warehouse Picking - The computer instructs each picker what to do with up to the second stock status from Put Aways. This would be especially valuable with items in multiple locations and where substitutions are possible.