SATO Etikettendrucker Selection Guide

Transcription

1 SATO Etikettendrucker Selection Guide Compliments of $9.95

2 Copyright Weddell Drive Sunnyvale, CA Revision E Second Edition Portions reprinted with permission of MARKET RESOURCES P.O. Box 981 Sandy, UT All rights reserved including those of translation. This book, or parts thereof, may not be reproduced in any form, stored in any retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior permission of SATO America, Inc. The information contained herein is based on the experience and materials collected from public information sources. is not responsible for the accuracy of its contents or for damages that might occur because of errors or omissions. does not, by publication of data in this book, ensure to anyone the use of such data against liability of any kind, including infringement of any patent. Publication of any data in this book does not constitute a recommendation of any patent or proprietary right that might be involved.

3 TABLE OF CONTENTS Bar Code Printing Basics Text vs. Bar Code...1 Specifications....2 Quality Considerations....3 Demand vs. Batch Printing...5 Selecting a Print Technology Direct Thermal....7 Thermal Transfer...9 Press Printing...10 Solid Font Impact Impact Dot Matrix...11 Laser...12 InkJet...13 Symbologies Linear Bar Codes D Bar Codes...17 Symbology Specifications...18 Label Considerations Design...20 Design Software Printing SATO Thermal Printers Thermal Printing...25 Direct Thermal vs. Thermal Transfer...28 Print and Apply...30 Specifications Summary...31 Feature Guide Bar Code Symbologies...34 Text Fonts...35 Label Formats...36 Label Edge Sensing...37 Resolution...38 System Options...39

4 Page ii Bar Code Printer Selection Guide Media Selection Direct Thermal Labels...40 Thermal Transfer Labels and Ribbons Adhesives Tag Media...44 For More Information...46

5 Bar Code Printing Basics There are two primary activities associated with bar code systems, printing the symbols and reading them. Both are equally important even though they are separate activities, performed at different times at different locations, and many times by different companies. It is essential that these two activities be coordinated if acceptable results are to be obtained. Something must be used to make sure both activities are operating under the same rules. Of the two activities, printing and reading, the first to be performed is the printing. After all, if something is be read, it must first be available in a readable form. Someone else may be printing the bar code symbol for you, as in the case of the UPC codes printed on items in the grocery store. Or you may be printing the symbol for someone else to read, such as would be the case if you were providing a product to be resold in the grocery store. Text vs. Bar Code In our modern information age, enormous amounts of data are moved from computer to computer every day. But computers have difficulty recognizing mistakes, giving rise to the phrase garbage in, garbage out. If you are depending upon the data to make important business decisions, it must be accurate, dependable and timely. Bar code systems are used to replace human data entry techniques because of two main attributes; The technology is very reliable, with extremely low read rate errors. CL608e 203 dpi 6" Wide CL408e 203 dpi 4" Wide CL412e 305 dpi 4" Wide CL612e 305 dpi 6.5" Wide SATO CLe Series Thermal Transfer Printers

6 Page 2 Bar Code Printer Selection Guide They are easily and inexpensively automated, increasing speed and productivity. To realize the benefits offered by bar codes, their capabilities and limitations must be understood. Bar code systems are not designed to duplicate the human visual capabilities, like OCR (Optical Character Recognition) systems which require complex imaging and recognition schemes, but to replace it with components designed with readily available and low cost technology. The human visual system is capable of deciphering very complex signals. It can decipher a symbol completely illegible to the machine. But the same visual system has great difficulty in taking large quantities of simple information, such as that represented by a bar code symbol, and reducing it to a single character. On the other end of the spectrum, the limited operational range of a machine scanner dictates that it operate under a very rigid and simple set of conditions. It can process huge quantities of simple information but requires very definable elements. For example, it wants to interpret a non-reflective part of a symbol as a bar. It is very poor at deciding if what was seen was a bar or a space with some garbage in it. To compensate for this deficiency, bar code label printers are optimized for printing simple symbols such as the bars in a bar code. Bar code printers are designed to produce the simple character elements that can be easily read by a machine scanner. Human text fonts in contrast are designed to fit the needs of the human that is interpreting them. Humans like to see all of those curlicues and serifs hanging off the end of the characters which makes it easier for the eye to string them together into words. Machine readers are more like the engineers that designed them, they see little use in anything that does not contain information. To them perfection is found in nice straight edges and consistent spacing. A simple matrix font formed from dots is sufficient to convey the necessary information. If larger characters are needed for visibility, simply expand the size by creating larger matrix elements using multiple dots to form each element. This results in the familiar stair-stepped characters that were characteristic of early dot matrix printers. However, humans have become accustomed to seeing smooth and nicely rounded characters that have been printed on their modern laser printers where they have a choice of fonts with which to express their individuality. Since most labels also contain information in a human readable form, it is necessary for us to compromise somewhere. Trying to make the human readable characters pleasing to the eye comes at a price, which is paid in increased memory storage requirements and/or reduced print speed. To store a number of large matrix fonts defining a complete range of character sizes requires a lot of memory. Memory storage can be reduced if the outline font approach is employed, like that used to define TrueType or PostScript fonts. Using this implementation, only the font definition is stored and is expanded by the processor when needed, but the time required to image a label becomes longer. If items are coming down a conveyor belt at a rate of one every five seconds, a slow printer that cannot keep up is not the correct answer. Specifications Application specifications perform the coordination task between the two activities. They are used to delineate the conditions under which a bar code symbol is to be printed and read later. At a minimum, the specifications should contain the following information: The symbology to be used. The density and size of the symbols. The allowable printing tolerances. Any check characters to be used to increase data integrity. The message content of the encoded data. Any data identifier characters to be included in the symbol. The size of the label.

7 Bar Code Printer Selection Guide Page 3 The location of each symbol on the label. Human readable information or graphic images to be included. The environmental conditions to which the label will be exposed. The material used for the label. The initial step in label printing is to carefully read the specification. If no specification exists, then the first order of business is to write one. It may be a simple one page memo or a document containing many pages. No matter how simple or controlled your application, you are asking for disaster without a specification. It establishes the ground rules under which everything must operate. Even though your scanner can read the labels your present printer is producing, there is no guarantee this will be the case if you should ever replace either with different equipment, or even if you change ribbon manufacturers. Quality Considerations The implementation of a successful bar code system starts with the symbol. The code is selected based upon data requirements and the capabilities of the scanning system used. Once selected, the next step in implementing a system is to record the symbol in a manner that will ensure readability at the proper time. This is a direct measure of the QUALITY of the printed symbol. A quality symbol must not only be within specifications at the time of printing, but must remain readable throughout its life. Because the symbol is being read by a scanner, its quality level should be judged against what the scanner expects to see. Here is an example of what you see is not necessarily what you get. The human eye may think the contrast between the bars and spaces is excellent, but if they are printed with red ink on a white background they will appear indistinguishable to a laser scanner operating in the infrared spectrum. If the bars are created by overprinting with a heavily inked ribbon on a dot matrix printer, then edge bleeding of the printed bars can result in wide spaces being interpreted by the scanner as narrow spaces. MEASURING PRINT QUALITY For an accurate determination of quality, the symbol should be measured with equipment that evaluates what the scanner will be looking for. There are many pieces of equipment, called verifiers, on the market that can make these measurements. They range from portable units with quick Go/No-Go readouts to ones that analyze the scanner signal and list the level of compliance for each parameter. Some will even make suggestions as to what can be done to improve the quality level of the symbol. Measurements made to the new ANSI standards will be letter graded, ranging from an A for excellent quality to an F for bar code symbols that do not fall within the specifications. Using these measurements, it is easy to spot symbols that are slowly deteriorating and take steps to rectify the cause before they become a problem in the field. It is common for application specifications to call for a letter grade one or two levels higher that the minimum requirements. This way, allowances are made for the symbol to degrade when exposed to environmental conditions and still be within the minimum specification limits when it is time to read them. Verifiers should be used with a heavy dose of common sense. Most quality printers designed for bar coding applications have few problems printing consistent symbols if they are maintained within the proper operating parameters (a good ribbon on a dot matrix printer for example). Therefore, a good sampling program can be used to maintain an acceptable quality level for most applications. Unless mandated by the customer, it is not usually necessary to verify each label as it is printed, unless your printer cannot give consistent results. If that is the case, it is time to get a better printer. What is important is whether or not the symbol can be read in the days or weeks ahead, after it has been sitting on someone s receiving dock for a couple of weeks.

8 Page 4 Bar Code Printer Selection Guide QUALITY VS. TECHNOLOGY Printing quality bar code labels depends upon several factors. First, the print technology chosen must be able to meet the technical requirements of the symbol. Thermal and laser printers can print almost any code density including the new ultra high density symbols, but dot matrix printers can only be used for low to medium density printing because of the physical size of the print wire. The technology must also meet the needs of the environment. A direct thermal label is of very high quality when it is first printed, but if the label is attached to a part going through a hot air shrink wrap machine, it can easily become useless. However, the same label is perfectly acceptable for a package of hamburger, neither can stand prolonged exposure to heat or sunlight. The next consideration is the base label material, which must be matched to both the print technology and the environment. If a symbol is generated by transferring ink to a label surface, then the ink must not only adhere at the time of printing, but throughout the useful life of the label. It must also provide a method of attachment to the item to be identified. This is commonly done using an adhesive-backed label material, but other methods may be used such as attachment using string or even being stapled to the item. Whatever method is used, it is critical that the label stay attached to the item. A label lying on the warehouse floor is as useless as one that cannot be read but still attached to the item. describe the symbologies used, the information encoded, the layout of the label and any additional text information and graphics that may be required. It will also outline the environmental requirements of the label and placement on the shipping cartons. The specification may follow the general requirements of an industry standard or may be specific to your particular customer. The customer may even level a penalty for labels that do not meet their specifications. Many follow the popular three strikes and you are out arrangement; the first time a label fails, you are fined, the second time one fails, you pay a larger fine, the third time one fails, they remove you from the approved vendor list. Your customer will undoubtedly institute some type of quality check on incoming labels. This can be as simple as scanning them to see if they read correctly or they may take a statistical sampling of the labels and use a bar code verifier to test them. Obviously you would like to COMPLIANCE LABELING Compliance labeling can be most accurately described as a You don t comply, I don t buy ultimatum from one of your customers. Your customer has mandated that you put a bar code label on all products shipped to them and have provided a specification. It should SATO CL408e Demand Label Printer

9 Bar Code Printer Selection Guide Page 5 catch any bad labels before they leave your shipping dock! Now is the time to create your own quality assurance program to make sure you are consistently producing labels to your customer s specifications. The quality assurance program should mirror that of your customer, so that when problems do occur (and they will occur), you are comparing apples to apples and can immediately identify and correct the problem. It may be that the incorrect ribbons or label stock was purchased. Or that preventive maintenance procedures were not followed, allowing the print quality to degrade. An on-line verifier system (one that checks each bar code as it is printed and interrupts the printing if an out of spec symbol is detected) may be needed if strict quality control measures are required. For less stringent requirements, a statistical sampling with a hand-held verifier may be all that is needed. Demand vs. Batch Printing? Many times people confuse when something is needed with how fast it is produced. With bar coded labels, it is not important how fast it was printed, but that it is available when the time comes to be used. The real restraint is the amount of time elapsed between when the information is available for printing and when the label is ready for use. Bar code label applications can be broken down into two time requirement categories, batch and demand, based on when the information is available to print the label relative to the time it is printed. BATCH PRINTING Batch printing implies that the data to be printed on the label is known far enough in advance to have them printed remote to the using location. Sometimes this leads to increased control problems. If the labels are serialized, for example, a voided or lost label can have serious consequences. On the other hand, if the label is produced at the point of usage at the time it is needed, the chances of it getting lost or placed on the wrong article are greatly reduced. Batch printing can be done in two basic ways, depending upon how much time the label data is known in advance. Off-Site Printing - If the information required to print the labels is known weeks or days in advance and the quantities used are sufficiently large, then label production becomes an exercise for the purchasing agent. There is tremendous latitude in label size, materials and supply format (i.e. rolls, sheets, individual, etc.). This is probably the most cost effective method of generating high quality labels, and most likely the only way of getting some specialty labels. However, an inventory level of labels is required to meet the usage requirements. If a large number of different labels are required, each must be inventoried with the accompanying increased likelihood that some will be scrapped as products undergo change. On-Site Printing - This is similar to the off site classification except the exact data for the labels is not known until hours in advance. Typical of this category would be date coded part number labels for a multi-product production line, only a few hours notice may be available when the line is converted to a different product. Depending upon the number of labels needed, the choices could range from an inhouse press to a high speed label printer. The incidence of scrappage is reduced since a smaller number of each label is printed during each production cycle. There is less latitude in material selection because prep and print time is limited. There is a wide selection of printer types, but the print technology is restricted to those that can be easily implemented at a remote location. As an example, press printing is The Trouble with Batch Printing

10 Page 6 Bar Code Printer Selection Guide not a good on-site choice because of the requirement for photographic plates, negatives, and other resource consuming tasks. DEMAND PRINTING Demand label applications require a unique label to be printed and presented at the point of use. This type of label generally contains a predetermined format with variable data sections, e.g. a serialized data field, that makes each label unique. The variable data, while it might be known in advance, is closely identified with a real time activity. The labels are intended to be used in conjunction with this activity as they are printed, or at least within a short time period after printing. Printing labels only when they are required has many advantages. It is also more restrictive on how the labels are produced. Demand printers can operate in the real time production environment. They accept data from the system and produce a label with data unique to that particular article. The variable data can be almost anything; serial numbers, sequence codes, test results, date codes, lot codes, etc. Because the labels are printed on the spot and usually one at a time, the type of printer needed has to meet a number of special requirements that do not apply to batch printing. Speed - The label must be ready when it is needed. This can be very fast, if an automatic applicator is used, or reasonably slow if a human operator takes the label and places it on the article. At the same time, the print process used must be simple and fast. Multi-step printers do not make good demand printers because of the time needed for set up. Presentation - The label must be presented to the applicator ready to be used immediately after it is printed. This could mean stripped with the adhesive back exposed or with the backing liner still attached but separated into individual labels by either tearing or cutting them apart. The last printed label must be easily accessible without wasting label stock. Media - The media must be universally usable for all label requirements supported by that printer. While it is possible to change label supplies to get different label sizes, pre-print information, etc., it is not feasible to change the media except on supply-type basis (i.e. one roll, one sheet, etc.). Because of their limited print field and media supply systems, demand label printers cannot efficiently produce text documents such as Bills of Lading and Shipping Notices. These types of applications are best left to ordinary computer printers that are designed to print human readable text documents with an occasional bar code field. The applications for which demand label printers are used can be categorized by the following: The labels are generated at the point of use. Each label or group of labels is unique. Labels are used in a real time environment.

11 Selecting A Print Technology All of the major print technologies have some advantages and disadvantages when used in a demand label application. It is possible to make a particular technology fit the application, but this generally involves compromises that may not make sense. It is more practical to select a printer based on a set of reasonable tradeoffs. For instance, a label printer is not often used for printing text documents, so this capability should not be included in the primary selection criteria. Before requirements can be matched to a particular type of printer, something must be known about the different characteristics of the technology and what they mean to bar code printing. Most of the familiar print technologies were developed for producing human readable text information. They can be modified to print bar codes, but what makes a good text printer does not necessarily make a good bar code printer. The more successful bar code printers have been optimized for this purpose. An example of optimization for bar code printing is the shape of the print dot used by matrix printers. A square or rectangular dot makes a bar with a very defined edge, something scanners like to see. A round dot produces a bar with a scalloped edge, harder for the bar code scanner to read, but it makes a human readable character that is more pleasing to the eye than the harsh corners of the square dot. Square dots make better bar codes while round dots are better suited for text documents. Another differentiation is the size of the print field. Text printers are designed to print document size pages, while label printers limit themselves to practical label sizes. Direct Thermal Direct thermal printing has more of a public image problem than a performance problem. While it is sensitive to heat and ultraviolet light, the degree is much less than most people suppose. It does offer one unique advantage not available in any other of the technologies presented here. It does not depend upon a secondary substance transfer to generate a mark on the paper. Direct thermal printing chemically alters a coating to produce the desired image. There is no secondary ink substance that must be disassociated from a carrier and made to adhere to the label surface. If the thermally active layer is covered by a protective coating, as all thermal printer manufacturers recommend, the image is shielded from surface abuse and contamination. The only thing that can get to it without first having to break down the protective layer is radiated energy in the form of either heat or ultraviolet light. Foreign contaminates or surface abuse must first destroy the protective coating before affecting the image. Protective Coating Binder Color Former A Base Paper Thermal Element Formed Image Color Former B Thermal Printing

12 Page 8 Bar Code Printer Selection Guide SATO M-5900RV Direct Thermal Printer ADVANTAGES Quality - Because of the square image elements and the non-reliance on a secondary substance transfer, direct thermal labels produce high quality bar codes with excellent bar edge definition. Simplicity - The absence of any ribbon/toner mechanisms makes the direct thermal mechanism inherently simple. This results in a less complex media loading path for more user friendly consumables handling. Resolution - The thermal print elements can produce a consistent dot pattern down to 5.0 mils (200 dpi) when printing in a horizontal mode (parallel to the paper movement). This allows ultra high density bar code printing. When printing in a vertical mode however, the speed must be reduced significantly to allow the elements to cool down before stepping to the next print position. While it is possible to print bars down to 5.0 mils when the print speed, paper sensitivity and power applied to the elements are carefully matched, it is best to avoid printing narrow dimensions of less than 10 mils in the horizontal mode and 15 mils in the vertical mode. Cost - The elimination of any ribbon/toner mechanism results in a lower initial printer cost. It also results in a more favorable consumable cost when compared to either thermal transfer or laser printers. LIMITATIONS Environment - The two most severe environmental limitations are exposure to high temperatures or prolonged exposure to direct sunlight. The development of new thermal papers has pushed the upper temperature range upward to about 212 F and special ultraviolet filter coatings can be applied that will extend the exposure time to sunlight from weeks to months and will retain an acceptable quality image for most purposes. Spectral Response - The bars created by the standard thermal dyes used in the label coatings are relatively transparent to infrared light, limiting the usefulness of standard label media to visible light scanners. Special label coatings are available that work with both visible and infrared light sources, but also increase the cost of the label. If it is to be read by both types of scanners, then the infrared stock should be specified. Media - The thermal paper used must match the characteristics for which the printer was designed. Because of the

13 Bar Code Printer Selection Guide Page 9 various speeds (sensitivity to heat) available in thermal papers, not all printer and paper combinations are compatible. When properly matched however, they will yield excellent quality bar code symbols. Thermal Element Backing Ribbon Thermal Transfer Thermal transfer printing is basically a direct thermal process that has a ribbon interposed between the head and the label. The heat from the print head is used to release the ink from a mylar ribbon and make it adhere to the label surface. Since this type of thermal process now relies upon a secondary substance transfer, some of the advantages of direct thermal are lost, but heat restrictions have been improved and sensitivity to ultraviolet light has been eliminated. ADVANTAGES Quality - The ink transferred to the label surface produces excellent bars with quite high contrast ratios which are very stable and resist deterioration. The use of square print dot elements also gives excellent bar edge quality. Resolution - The thermal print elements can produce a consistent dot pattern down to 1.67 mils (600 dpi) when printing in a horizontal mode (parallel to the paper movement), allowing ultra high density bar code printing. When printing in a vertical mode however, the speed must be reduced significantly to allow the elements to cool down before stepping to the next print position. While it is possible to print bars below 5.0 mils when the print speed, paper, ribbon and power applied to the elements are carefully matched, it is best to avoid printing bar codes with a narrow dimension of less than 10 mils in the horizontal mode and 15 mils in the vertical mode. Label Sheet Thermal Transfer Printing Speed - Because it takes less energy to release the ink from the ribbon than it does to develop a dot using thermally sensitive paper, the print speed of thermal transfer printers is faster than their direct thermal cousins. With the same print head and mechanism, it is typically twice as fast when printing comparable images in the direct thermal mode. Dual Mode Printing - Since the thermal transfer printer is essentially a thermal mechanism with a ribbon positioned between the head and the paper, it can also be used to print in a direct thermal mode if the ribbon is not used. However, the head life will be considerably reduced because it is no longer protected by the ribbon. Media Selection - Bar code symbols can be generated using a wider range of paper and vinyl substrates that are more resistive to heat, water and light than in the direct thermal process. By proper selection of the label material and the ribbon, a very strong bond may be obtained between the ink and the label surface, giving performance comparable to direct thermal labels with protective surface laminations. LIMITATIONS Hot Melt Ink Transferred Ink Ribbons - The ribbons are single pass and the printing of a single dot in a row

14 Page 10 Bar Code Printer Selection Guide wastes the remaining ink on that row. This results in a very high ribbon usage and associated cost. The ribbons are a thin mylar or similar material coated with ink on one side and can be difficult to handle, especially if they are very wide. Label Cost - Because of the high ribbon usage, usually on the order of one ribbon roll for each two rolls of labels, the cost of labels is higher than with most of the other common technologies. Ribbon/Media Compatibility - The adherence of the ink to the surface is the source of most of the durability problems with thermal transfer images. If improper ribbon formulations are used, the transferred ink may flake at the edges when contact scanners are used, or become smudged from oily finger prints. Press Printing This category encompasses all of the press technology available for off-site printing. This includes film masters, flexography, offset lithography, gravure, letterset, hot stamping and many others. It offers the widest range of quality labels available for bar code printing. The most important step for procuring off-site printed labels is the generation of a good specification for the label, detailing the precise dimensions of the symbols and media upon which they are to be printed. Selection of a label vendor should be based primarily upon their experience and reputation. This probably won t be the lowest cost bidder, but will most likely represent the lowest overall cost if headaches and mistakes are taken into consideration. ADVANTAGES Label Material Selection - Because of the many print processes available for use, the range of materials available on which bar codes may be printed is almost limitless. Special materials are available for high temperatures, and even metal plates can be imprinted with bar coded information. Cost - If a large quantity of identical labels are required and they do not have any special requirements to drive up the price, cost per label will be relatively inexpensive. Quality - High quality should be expected for press printed labels. While it is possible to get low quality labels using off-site vendors, the cause can usually be traced to poor workmanship or a lack of understanding of the bar code symbol requirements. Excellent quality labels that survive under harsh conditions can be obtained by the selection of the correct print process and base label material. Label Size - The printable label size is limited only by the dimensions of the press web, which can be very large. LIMITATIONS Variable Data - It is difficult to print labels where each one must contain different data. Even sequential numbering using bar code symbols is a task. It involves not just the changing of a single character, but the rearrangement of a series of bars and spaces. Advance Data - The data for the label(s) to be printed must be known far enough in advance to allow for the preparation of the print masters and scheduling of press time. If special labels are needed, extra time must be allowed to obtain any nonstandard materials. Cost - If only a small number of labels are needed, the cost per label can be high, reflecting set-up charges that are now prorated over fewer labels. Solid Font Impact Solid font impact printers come the closest to typewriters in technology and limitations. They print the bar codes by constructing the

15 Bar Code Printer Selection Guide Page 11 symbols with preformed bars or by printing the complete character with a single hammer blow. The constructed code method must be used if the symbol to be printed represents a large area per hammer blow, or if a continuous code is chosen. ADVANTAGES Simple Interfacing - Send the printer a character code and that is what it prints. No worrying about aspect ratios, different code symbologies, etc. Quality - Since each bar is precisely formed, the edge definition is excellent and good quality bar code symbols are produced. LIMITATIONS Fixed Format - Since each bar or symbol is preformed, the label format, symbology codes or character densities cannot be changed without changing the code wheel. Alpha characters may be printed, but are restricted to a particular location determined by their position on the code wheel. All symbols must be printed in the same orientation, and orthogonally (i.e. at right angles) printed symbols cannot be produced. Speed - Each bar or symbol is located sequentially on the code wheel and the print speed is limited by the rotational speed of the wheel. Mechanical - The operation of the mechanism depends upon numerous moving parts with large masses. The hammer blows and code wheel rotation must be properly synchronized or smearing will result. Symbol Area - If small area symbols are printed, there is a tendency for ticking to occur. This is ink transfer in areas between characters or on edge of adjacent characters. Impact Dot Matrix Dot matrix printers are very popular in the computer industry for document printing. Many have been pressed into bar code service because they are cheap and everyone with a computer probably already has one. However, the ones best suited for bar code applications are the line printer types, the ones that are not cheap and only used in limited computer applications. The most effective dot matrix printers generally have additional intelligence in the form of a graphics controller card to reduce transmission time for complex labels. ADVANTAGES Versatility - Dot matrix printers are one of the most versatile types available. They can print bar code symbols or text documents in any orientation and with various height and width symbols. They are especially adept at printing multicopy forms that include bar code symbols for document tracking and control. When printing bar codes on multi-copy forms however, the top copy will be the only one readable by a scanner. Equipment Cost - Dot matrix printers are used in large quantities by the computer industry and the initial cost of the equipment is low. However, care should be exercised in selecting a dot matrix printer for bar code applications on the basis of price or availability. Also make sure it can print suitable quality symbols. LIMITATIONS Carriage Width - Most of the common dot matrix printers were designed primarily for printing documents. The width of the carriage is determined by the smallest sheet size (usually 8.5" x 11"). Bar code labels tend to be much smaller and have to be printed multiple up to take advantage of the print speed. Also, if the printer uses the standard puller tractor arrangement, the label must clear the tractor assembly before it is easily acces-

16 Page 12 Bar Code Printer Selection Guide sible. Fitting a label stripper or cutter to such a printer presents some mechanical challenges. Quality - When used to print bar code symbols, dot matrix printers have several factors going against them. First, the edge definition of the bar is poor and overlapping dots must be used to meet the specifications. When overprinting to increase the bar density and fill in the ragged edges, new ribbons will bleed excessively at the bar edge causing bars to be too wide and the adjacent spaces too narrow, while worn ribbons not containing enough ink will tend to print the bars will too narrow with adjacent spaces being too wide. Second, irregular paper spacing will cause problems with vertically printed symbols. If the printer uses a serially driven head, then irregular head motion will result in problems with horizontally printed symbols. Spectral Response - The standard ink in a dot matrix printer ribbon is not readable to scanners using infrared light. Carbon must be added to make it infrared scannable, but carbon will cause the print head to wear out prematurely. Special mylar ribbons using carbon have been Toner Bin developed to overcome this problem, but most are single pass and have a very limited lifetime. The dry carbon transferred from the mylar ribbons must adhere to the surface since it is not absorbed by the label material. Resolution - The best resolution offered by dot matrix printers comes from the 24 pin print heads that use 8 mil diameter print wires. When ink bleed is taken into consideration, the dot size will end up between 9 and 10 mils, giving a medium density bar code symbol at best. When printing low density symbols such as those called for by the AIAG B-3 Shipping Label, the 8 mil wire requires several overlapping dot rows to print the proper bar width. Conversely, printers using nine pin heads with 12 mil print wires can create the symbol more easily, but are limited to printing only low density bar codes. Laser The term laser is used here to refer to any printer using a xerographic or similar type of printing process. Liquid Crystal Shutter (LCS) arrays, Light Emitting Diode (LED) arrays or lasers are used to expose the surface of the image Paper Direction Exposure Area Drum Corona Wire Transfer Corona Wire Developer Bin Fusing Rollers OPC Drum Laser Printing

17 Bar Code Printer Selection Guide Page 13 drum, with the laser being the most popular. These printers are invariably page printers and are not well suited for demand label applications. They are most commonly sheet fed printers, but some of the newer laser printers designed for bar code applications employ a tractor feed system whereby continuous forms may be used. ADVANTAGES Aesthetics - Laser printers commonly have a resolution of at least 300 dots per inch, with some of the newer models being capable of printing at 600 or 1200 dpi. This allows them to print almost typeset quality characters and high resolution graphic images. These can be combined with bar code symbols on a label to produce very nice looking labels with complicated designs. Resolution - At 300 dots per inch resolution (a 3.3 mil dot size), laser printers can create ultra high density bar code symbols. However, it is not generally recommended that bars be printed less than 6.6 mils (two dots wide on a 300 dpi printer) unless the symbol is to be scanned in closed loop applications where the scanning equipment used can be controlled. Multi-Application - Lasers are the printers of choice for documents where bar code symbols and quality document printing must be intermixed. Limitations Page Printer - Since laser printers are basically page printers, it takes as much time and media to print a single small label as it does a large label. If it prints at six pages per minute, it takes 10 seconds to print a whole page or a single bar code symbol. Some of the newer laser printers designed for bar code applications have a variable page length feature, but the physical distance between the imaging drum and the fusing roller prevents an image from being placed immediately following the previous image. They are therefore poor choices for typical demand label applications. Heat - Laser printers use heat to fuse the toner to the surface of the paper, a lot of heat. The adhesive coating on the back of a label tends to seep out between the die cut edges when heat is applied. In ion deposition printers, the heat is replaced by pressure, but the result can be the same. Special adhesives must be specified for these printers. Label Imaging Time - Because of the large number of dots per inch, the time required to image a label can be substantial. Compounding the problem is the requirement for a complete page to be imaged even if it consists of a number of identical smaller labels. Ink Jet Ink jet printing has several drawbacks when used for printing bar code symbols, but does find some use in specialized applications. The main problems with bar code printing are involved with the formation and control of the dot. Since the ink is absorbed, the paper porosity, ink viscosity and drying time must be carefully controlled. The most pronounced symbol quality problems are associated with the edge definition, contrast ratio and consistent bar widths. Some of the new ink jet techniques use a solid ink that is liquefied with heat and placed on the paper where it reverts to its solid state. This gives better edge definition and contrast ratios but leaves a raised print image which can cause problems with contact scanners. Special ink jet systems have been developed to print low resolution bar codes directly on corrugated surfaces. Using independently mounted nozzles, the images are formed as the container is moved by on a conveyor system.

18 Page 14 Bar Code Printer Selection Guide Ink Droplets Nozzle Advantages Non-contact - The primary advantages of ink-jet printing is that it is a non-contact printing technology. This removes any wear on the head due to contact abrasion. This also allows surfaces with irregular finishes to be printed if they are compatible with the ink. DISADVANTAGES To Ink Supply Ink Jet Printing Piezoelectric Transducer Control Voltage Media Surface - The ink must be absorbed into the surface of the media, requiring a controlled surface porosity and finish. Because bar codes involve much higher printing densities than text, the media requires a longer period of time to dry sufficiently before it can be handled without smearing. Ink Formulation - The ink must dry quickly, but not in the nozzle. The compromise between these two extremes requires the head to be purged or cleaned between print jobs. Water based inks are also very susceptible to exposure to moisture. A single drop of water can render a bar code unreadable. Infrared Response - If infrared scanners are used, carbon or some other infrared absorbing material must be added to the ink. This can cause excessive wear on the ink nozzles. Matching Technology and Requirements The selection of the proper technology for generating bar coded labels is a very complex process. It involves not only an understanding of the print technology to be used, but the label usage requirements as well. These two bodies of knowledge must be combined in the selection process to ensure that the bar code labels produced will give satisfactory performance for their required lifetime. Some of the factors to be considered are: What are the environmental requirements? What is the total cost target per label? Does the data content change? How will the label be scanned? How will the label be applied? How often will a label be required i.e., (10 labels per second, etc)?

19 Symbologies Linear Bar Codes Linear bar codes are uni-dimensional, i.e. the same data is present in all vertical elements. If you increase the number of characters in a linear bar code, it expands horizontally. The vertical dimension remains unchanged. Increasing the height of a linear bar code does not change its data capacity, just the ease of scanning. Five bar codes represent the great majority of all bar code usage. They are the UPC/EAN, Code 39, Interleaved 2 of 5, Codabar and Code 128. All of these are linear bar codes that are easy to print using a variety of printers. Of these five, UPC/EAN and Code 39 are by far the most commonly used, but Code 128 is rapidly gaining acceptance for new applications. Other codes have been designed for specific purposes, but do not enjoy wide usage. These five codes represent a wide range of capabilities. UPC/EAN, Codabar and Interleaved 2 of 5 being capable of only encoding numerics, while Code 39 can also encode uppercase alphas and Code 128 the full ASCII character set. UPC/EAN and Code 128 are four level codes, with each element being either 1X, 2X, 3X or 4X the width of a narrow bar. Code 39, Codabar and Interleaved 2 of 5, on the other hand, are two level codes having only two possible widths, either wide or narrow. The wide to narrow ratio for these codes is limited to a range from 2:1 to 3:1, with the minimum being 2.2:1 for codes having narrow bar dimensions of less than 20 mils (.020"). It should be noted that the two level codes have twice the printing tolerance when printed at 3:1 than the four level codes. The scanner has to only distinguish between a bar three times as wide as the narrow one. In the four level code, it has to determine when a bar is only twice as wide. To get an accurate density comparison between the two level and four level codes with all factors being equal, the wide to narrow ratio for the two level code should be set to 2:1. CODE 39 Code 39 is an alpha numeric code that encodes 43 characters. It is a discrete code, i.e. one where each character starts with a bar and ends with a bar and has a discrete space between characters. Each character in Code 39 is represented by five bars and four spaces, with three of the nine elements being wide and the remaining six narrow. It is a two level code, with the wide to narrow ratio being restricted between a range of 2:1 (2.2:1 for narrow bar widths under 20 mils) and 3:1. Unique start/stop characters are added at the beginning and end of the decoded data and are conventionally decoded as an asterisk. Code 39 is widely used in industrial applications because of its variable length feature and the ability to encode alphas as well as numerics. Code 39 is specified for usage by the Automotive Industry Action Group (AIAG), the Department of Defense s MIL SPEC 1189 LOGMARS specification and the Health Industry Bar Code Council (HIBCC). UPC The UPC code was established for the benefit of the supermarket industry to facilitate automatic scanning of items at the checkout counter. It is a four level numeric only code that is continuous, i.e. one that starts with a bar and ends with a space and has no intercharacter

20 Page 16 Bar Code Printer Selection Guide gap. Characters are constructed from a combination of two bars and two spaces, and occupy a total of 7 module widths. It is a fixed length code with the standard UPC-A symbols having one number system digit, ten data digits and one check digit in addition to the start/stop characters. When printed at 100% magnification (a 13 mil narrow bar dimension), it is inches long. The specification allows it to be printed as large as 200% and as small as 80%. The 80% limitation makes it difficult for a modern discrete dot printer to create both a 100% and an 80% symbol since it would require a dot size of 2.6 mils to construct both within specifications, a size found only in printers designed specifically to meet these requirements. Several variations of the UPC code exist. The EAN (European Article Numbering) variation encodes 13 characters, with the extra digit being combined with the number system digit to encode the country of origin. A shortened version, UPC-E can be used for products that do not have adequate room for the full symbol. INTERLEAVED 2 OF 5 Interleaved 2 of 5 is a numeric only bar code that has been widely accepted in warehouse and heavy industry applications. It is a continuous code and uses combinations of bars to encode one digit and the intervening spaces to encode another. Therefore any symbol must contain an even number of characters. A char- A B C D E F A b C d E f Code 39, 12 characters, 13 mil Code 128, 12 characters, 13 mil UPC-A, 12 characters, 13 mil A D Codabar, 12 characters, 13 mil EAN-13, 13 characters, 13 mil I 2 of 5, 12 characters, 13 mil UPC-E, 6 characters, 13 mil UPC-A, 5 Supplemental, 17 characters 13 mil Symbology Comparisons

21 Bar Code Printer Selection Guide Page 17 acter is composed of two wide bars (or spaces) out of a total of five, using only two possible widths, either wide or narrow. Special start and stop characters are used to delineate the encoded data. Because of its use of all the bar and space elements for encoding data, it is regarded as a high density code. A check digit can be used to increase the reliability of the code. CODABAR Codabar is a discrete two level code with each character represented by a standalone group of four bars and three intervening spaces. A total of 16 characters are defined and four different start/stop characters used. This allows 16 different sets of data to be encoded using the possible start/stop character combinations. The original Codabar specification was optimized for ink spread in press printing, resulting in 18 possible element widths. Most modern printers use a rationalized version of the code that reduces the number of possible widths to two, making it more compatible with modern discrete dot printers. A check digit is optional if data integrity is critical. CODE 128 Code 128 is one of the newer kids on the block and is becoming very popular because of its high density and ability to encode a full character set. It is a four level discrete code with three possible start characters and one stop character, with each of the four combinations describing a separate character set. Subset A includes all of the standard uppercase alphanumeric keyboard characters plus the control and special characters. Subset B includes all of the standard uppercase alpha-numeric keyboard characters plus lower case alpha and special characters. Subset C includes the set of 100 digit pairs from 00 thru 99 inclusive, as well as special characters which allow double density numeric digit pairs to be encoded. It has a structure with 11 modules, each having three bars and three spaces. A check digit is mandatory. The combination of high density, the ability to encode 128 characters and the development of laser and thermal bar code printers capable of printing high quality symbols with small bar dimensions has fueled the popularity of Code 128. It is being specified for a number of applications, including the new UCC-128 Serial Shipping Container Code. 2-D Bar Codes 2-D bar codes were developed in an attempt to overcome the conventional information limitations of linear bar code symbols. As the amount of information encoded increases, there are only two options available with linear bar codes, make them longer or use multiple symbols. As the symbols become longer they consume more room and become a problem for scanners as they fall outside the allowable scan angle. Breaking the information up into a number of standalone symbols requires that each be read individually and that the contents of each be identifiable from that of the other symbols as the order of scanning cannot be ensured. The AIAG-B3 shipping label is an excellent example of conventional symbols being arranged one above another. In this case each symbol is read separately and the system must correlate the information. By using Data Identifier characters, the system knows what information is contained in the symbol regardless of the order scanned. However, the limitation of this approach is apparent. The 2-D symbologies take advantage of both horizontal and vertical encodation to reduce the symbol size and achieve character densities up to 2000 characters per square inch. There are two primary approaches taken. The first is to stack high density linear symbols with very small vertical measurements. The other is to use a pattern code in which data can be encoded in an X-Y matrix. STACKED CODES PDF417, Code 49 and Code 16K are examples of stacked symbologies. The most popular of these is PDF417, developed by Symbol Technologies, Inc. in It is easily recognized by the continuous start and stop codes that run the entire height of the symbol. In between the start/stop codes are a number of linear bar codes stacked directly on top of each other. The