SATO Etikettendrucker
Selection Guide
Sunnyvale, CA 94089
Revision E
Second Edition
Portions reprinted with permission of
MARKET RESOURCES
P.O. Box 981
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America, Inc
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. is not responsible for the accuracy of its contents or for
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America, Inc.
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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. . . 10
Impact Dot Matrix . . . 11
Laser
. . . 12
Ink Jet . . . 13
Symbologies
Linear Bar Codes . . . 15
2-D Bar Codes . . . 17
Symbology Specifications . . . 18
Label Considerations
Design . . . 20
Design Software. . . 21
Printing. . . 23
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
Media Selection
Direct Thermal Labels . . . 40
Thermal Transfer Labels and Ribbons. . . 41
Adhesives. . . 43
Tag Media . . . 44
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, per-formed at different times at different locations, and many times by different companies. It is es-sential that these two activities be coordinated if acceptable results are to be obtained. Some-thing 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 avail-able in a readavail-able 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 sym-bol 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 diffi-culty recognizing mistakes, giving rise to the phrase “garbage in, garbage out.” If you are de-pending upon the data to make important busi-ness decisions, it must be accurate, dependable and timely. Bar code systems are used to re-place human data entry techniques because of two main attributes;
•
The technology is very reliable, with ex-tremely low read rate errors.SATO CLe Series Thermal Transfer Printers
CL408e
203 dpi
4" Wide
CL608e
203 dpi
6" Wide
CL612e
305 dpi
6.5" Wide
CL412e
305 dpi
4" Wide
•
They are easily and inexpensively auto-mated, increasing speed and productiv-ity.To realize the benefits offered by bar codes, their capabilities and limitations must be un-derstood. Bar code systems are not designed to duplicate the human visual capabilities, like OCR (Optical Character Recognition) systems which require complex imaging and recogni-tion schemes, but to replace it with components designed with readily available and low cost technology.
The human visual system is capable of deci-phering 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 opera-tional 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 com-pensate for this deficiency, bar code label print-ers 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 hu-man that is interpreting them. Huhu-mans 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 any-thing 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. How-ever, humans have become accustomed to see-ing smooth and nicely rounded characters that have been printed on their modern laser print-ers 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 compro-mise somewhere.
Trying to make the human readable charac-ters pleasing to the eye comes at a price, which is paid in increased memory storage require-ments and/or reduced print speed. To store a number of large matrix fonts defining a com-plete 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. Us-ing this implementation, only the font defini-tion 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 sec-onds, a slow printer that cannot keep up is not the correct answer.
Specifications
Application specifications perform the coor-dination 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 in-crease data integrity.•
The message content of the encoded data.•
Any data identifier characters to be in-cluded in the symbol.•
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 care-fully 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 rib-bon manufacturers.
Quality Considerations
The implementation of a successful bar code system starts with the symbol. The code is se-lected based upon data requirements and the capabilities of the scanning system used. Once selected, the next step in implementing a sys-tem 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 scan-ner, its quality level should be judged against what the scanner expects to see. Here is an ex-ample 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 back-ground they will appear indistinguishable to a laser scanner operating in the infrared spec-trum. 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 equip-ment that evaluates what the scanner will be looking for. There are many pieces of equip-ment, 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 specifica-tions. Using these measurements, it is easy to spot symbols that are slowly deteriorating and take steps to rectify the cause before they be-come a problem in the field. It is common for application specifications to call for a letter grade one or two levels higher that the mini-mum 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 main-tainedwithin the proper operating parameters (a good ribbon on a dot matrix printer for ex-ample). 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 ver-ify 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 impor-tant is whether or not the symbol can be read in the days or weeks ahead, after it has been sit-ting on someone’s receiving dock for a couple of weeks.
QUALITY VS. TECHNOLOGY
Printing quality bar code labels depends upon several factors. First, the print technology chosen must be able to meet the technical re-quirements of the symbol. Thermal and laser printers can print almost any code density in-cluding the new ultra high density symbols, but dot matrix printers can only be used for low to medium density printing because of the physi-cal size of the print wire. The technology must also meet the needs of the environment. A di-rect 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 ma-chine, it can easily become useless. However, the same label is perfectly acceptable for a package of hamburger, neither can stand pro-longed exposure to heat or sunlight.
The next consideration is the base label ma-terial, 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 through-out the useful life of the label. It must also provide a method of at-tachment to the item to be identi-fied. 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 criti-cal that the label stay attached to the item. A label lying on the ware-house floor is as useless as one that cannot be read but still attached to the item.
COMPLIANCE LABELING
Compliance labeling can be most accurately described as a “You don’t comply, I don’t buy” ultima-tum from one of your customers. Your customer has mandated that you put a bar code label on all prod-ucts shipped to them and have pro-vided a specification. It should
describe the symbologies used, the information encoded, the layout of the label and any addi-tional text information and graphics that may be required. It will also outline the environ-mental requirements of the label and place-ment on the shipping cartons.
The specification may follow the general re-quirements of an industry standard or may be specific to your particular customer. The cus-tomer may even level a penalty for labels that do not meet their specifications. Many follow the popular “three strikes and you are out” ar-rangement; 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 veri-fier to test them. Obviously you would like to
catch any bad labelsbefore they leave your ship-ping dock!Now is the time to create your own quality assurance program to make sure you are consistently producing labels to your cus-tomer’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 prob-lem. It may be that the incorrect ribbons or la-bel stock was purchased. Or that preventive maintenance procedures were not followed, al-lowing 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 meas-ures are required. For less stringent require-ments, 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 in-formation is available for printing and when the label is ready for use. Bar code label appli-cations can be broken down into two time re-quirement 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 ad-vance 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, depend-ing upon how much time the label data is known in advance.
Off-Site Printing - If the information
re-quired to print the labels is known weeks or days in advance and the quantities used are suf-ficiently 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 spe-cialty labels. However, an inventory level of la-bels is required to meet the usage requirements. If a large number of different labels are re-quired, each must be inventoried with the ac-companying 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 produc-tion line, only a few hours notice may be avail-able when the line is converted to a different product. Depending upon the number of labels needed, the choices could range from an in-house 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 re-mote location. As an example, press printing is
not a good on-site choice because of the re-quirement 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 pre-determined format with variable data sections, e.g. a serialized data field, that makes each la-bel 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 pe-riod after printing.
Printing labels only when they are required has many advantages. It is also more restrictive on how the labels are produced. Demand print-ers can operate in the real time production en-vironment. They accept data from the system and produce a label with data unique to that particular article. The variable data can be al-most 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 hu-man 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
print-ers do not make good demand printprint-ers because of the time needed for set up.
Presentation - The label must be
pre-sented to the applicator ready to be used imme-diately after it is printed. This could mean stripped with the adhesive back exposed or with the backing liner still attached but sepa-rated 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
us-able for all label requirements supported by that printer. While it is possible to change label supplies to get different label sizes, pre-print in-formation, 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 me-dia supply systems, demand label printers can-not 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 hu-man readable text documents with an occa-sional 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 environ-ment.All of the major print technologies have some advantages and disadvantages when used in a demand label application. It is possi-ble to make a particular technology fit the ap-plication, 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 docu-ments, 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 exam-ple 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 scal-loped 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 differentia-tion is the size of the print field. Text printers are designed to print document size pages, while label printers limit themselves to practi-cal 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 sup-pose. It does offer one unique advantage not available in any other of the technologies pre-sented here. It does not depend upon a secon-dary 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 ad-here 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 protec-tive layer is radiated energy in the form of ei-ther heat or ultraviolet light. Foreign contaminates or surface abuse must first de-stroy the protective coating before affecting the image.
Thermal Printing
Binder Color Former A Base Paper Protective Coating Formed Image Color Former B Thermal ElementADVANTAGES
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Quality - Because of the square image elements and the non-reliance on a sec-ondary substance transfer, direct ther-mal labels produce high quality bar codes with excellent bar edge definition.•
Simplicity - The absence of any rib-bon/toner mechanisms makes the direct thermal mechanism inherently simple. This results in a less complex media load-ing path for more user friendly consum-ables handling.•
Resolution - The thermal print elements can produce a consistent dot pattern down to 5.0 mils (200 dpi) when print-ing 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 beforestep-ping to the next print position. While it is possible to print bars down to 5.0 mils when the print speed, paper sensi-tivity and power applied to the elements are carefully matched, it is best to avoid printing narrow dimensions of less than 10 mils in the hori-zontal mode and 15 mils in the vertical mode.
•
Cost - The elimination of any ribbon/toner mechanism re-sults in a lower initial printer cost. It also results in a more favorable consumable cost when compared to either thermal transfer or laser print-ers.LIMITATIONS
•
Environment - The two most severe environmental limita-tions are exposure to high temperatures or prolonged exposure to direct sunlight. The develop-ment 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 la-bel coatings are relatively transparent to infrared light, limiting the usefulness of standard label media to visible light scanners. Special label coatings are avail-able that work with both visible and in-frared 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 thevarious “speeds” (sensitivity to heat) available in thermal papers, not all printer and paper combinations are com-patible. When properly matched how-ever, they will yield excellent quality bar code symbols.
Thermal Transfer
Thermal transfer printing is basically a di-rect thermal process that has a ribbon inter-posed 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 trans-fer, some of the advantages of direct thermal are lost, but heat restrictions have been im-proved 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 ex-cellent bar edge quality.•
Resolution - The thermal print elements can produce a consistent dot pattern down to 1.67 mils (600 dpi) when print-ing 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 step-ping 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 care-fully 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.•
Speed - Because it takes less energy to re-lease the ink from the ribbon than it does to develop a dot using thermallysensi-tive 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 be-tween 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 pa-per and vinyl substrates that are more re-sistive to heat, water and light than in the direct thermal process. By proper selec-tion of the label material and the ribbon, a very strong bond may be obtained be-tween the ink and the label surface, giv-ing performance comparable to direct thermal labels with protective surface laminations.LIMITATIONS
•
Ribbons - The ribbons are single pass and the printing of a single dot in a rowThermal Transfer Printing
Backing Ribbon Hot Melt Ink Thermal Element Transferred Ink Label Sheet
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 ad-herence of the ink to the surface is the source of most of the durability problems with thermal transfer images. If im-proper ribbon formulations are used, the transferred ink may flake at the edges when contact scanners are used, or be-come 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 li-thography, 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 speci-fication for the label, detailing the precise di-mensions of the symbols and media upon which they are to be printed. Selection of a la-bel 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 head-aches 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 limit-less. Special materials are available for high temperatures, and even metalplates can be imprinted with bar coded information.
•
Cost - If a large quantity of identical la-bels are required and they do not have any special requirements to drive up the price, cost per label will be relatively in-expensive.•
Quality - High quality should be expected for press printed labels. While it is possi-ble to get low quality labels using off-site vendors, the cause can usually be traced to poor workmanship or a lack of under-standing of the bar code symbol require-ments. 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 la-bels where each one must contain differ-ent data. Even sequdiffer-ential numbering using bar code symbols is a task. It in-volves not just the changing of a single character, but the rearrangement of a se-ries 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 non-standard materials.•
Cost - If only a small number of labels are needed, the cost per label can be high, re-flecting set-up charges that are now pro-rated 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 thesymbols 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, differ-ent 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, sym-bology codes or character densities can-not 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 or-thogonally (i.e. at right angles) printed symbols cannot be produced.•
Speed - Each bar or symbol is located se-quentially 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 smear-ing will result.•
Symbol Area - If small area symbols are printed, there is a tendency for “ticking” to occur. This is ink transfer in areas be-tween 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 appli-cations. 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
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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 multi-copy 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 equip-ment is low. However, care should be ex-ercised 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
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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 ad-vantage of the print speed. Also, if the printer uses the standard puller tractor arrangement, the label must clear the tractor assembly before it is easilyacces-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 ex-cessively at the bar edge causing bars to be too wide and the adjacent spaces too narrow, while worn ribbons not contain-ing enough ink will tend to print the bars will too narrow with adjacent spaces be-ing too wide. Second, irregular paper spacing will cause problems with verti-cally 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 scan-nable, but carbon will cause the print head to wear out prematurely. Special mylar ribbons using carbon have beendeveloped to overcome this problem, but most are single pass and have a very lim-ited lifetime. The dry carbon transferred from the mylar ribbons must adhere to the surface since it is not absorbed by the label material.
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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 la-sers are used to expose the surface of the image
Laser Printing
OPC Drum Fusing Rollers Exposure Area Toner Bin Developer Bin Transfer Corona Wire Paper Direction Drum Corona Wiredrum, with the laser being the most popular. These printers are invariably page printers and are not well suited for demand label applica-tions. They are most commonly sheet fed print-ers, but some of the newer laser printers designed for bar code applications employ a tractor feed system whereby continuous forms may be used.
ADVANTAGES
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Aesthetics - Laser printers commonly have a resolution of at least 300 dots per inch, with some of the newer models be-ing capable of printbe-ing at 600 or 1200 dpi. This allows them to print almost typeset quality characters and high reso-lution graphic images. These can be com-bined with bar code symbols on a label to produce very nice looking labels with complicated designs.•
Resolution - At 300 dots per inch resolu-tion (a 3.3 mil dot size), laser printers can create ultra high density bar code symbols. However, it is not generally rec-ommended 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 print-ers of choice for documents where bar code symbols and quality document printing must be intermixed.Limitations
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Page Printer - Since laser printers are ba-sically page printers, it takes as much time and media to print a single small la-bel as it does a large lala-bel. 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 animage from being placed immediately following the previous image. They are therefore poor choices for typical de-mand label applications.
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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 speci-fied for these printers.•
Label Imaging Time - Because of the large number of dots per inch, the time required to image a label can be substan-tial. Compounding the problem is the re-quirement 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 in-volved with the formation and control of the dot. Since the ink is absorbed, the paper poros-ity, ink viscosity and drying time must be care-fully 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.
Advantages
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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 abra-sion. This also allows surfaces with ir-regular finishes to be printed if they are compatible with the ink.DISADVANTAGES
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Media Surface - The ink must be ab-sorbed into the surface of the media, re-quiring 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. Thecom-promise between these two extremes re-quires the head to be purged or cleaned between print jobs. Water based inks are also very susceptible to exposure to mois-ture. A single drop of water can render a bar code unreadable.
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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 selec-tion 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:
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What are the environmental require-ments?•
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)?Ink Jet Printing
Ink Droplets Control Voltage Piezoelectric Transducer Nozzle To Ink Supply
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. In-creasing 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 gain-ing 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 Inter-leaved 2 of 5 being capable of only encoding numerics, while Code 39 can also encode up-percase 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 dimen-sions 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 en-codes 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 be-tween 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 begin-ning and end of the decoded data and are con-ventionally 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 De-fense’s MIL SPEC 1189 LOGMARS specification and the Health Industry Bar Code Council (HIBCC).
UPC
The UPC code was established for the bene-fit 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
gap. Characters are constructed from a combi-nation 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%” magnifica-tion (a 13 mil narrow bar dimension), it is 1.235 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 re-quire a dot size of 2.6 mils to construct both within specifications, a size found only in print-ers 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 be-ing combined with the number system digit to encode the country of origin. A shortened ver-sion, 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 continu-ous code and uses combinations of bars to en-code one digit and the intervening spaces to encode another. Therefore any symbol must contain an even number of characters. A
char-Symbology Comparisons
UPC-E, 6 characters, 13 mil EAN-13, 13 characters, 13 mil
Code 39, 12 characters, 13 mil Code 128, 12 characters, 13 mil
Codabar, 12 characters, 13 mil
I 2 of 5, 12 characters, 13 mil
UPC-A, 5 Supplemental, 17 characters 13 mil
UPC-A, 12 characters, 13 mil
A B C D E F 1 2 3 4 5 6 A b C d E f 1 2 3 4 5 6 0 12345 67890 5 A 0 1 2 3 4 5 6 7 8 9 0 1 D 0 123456 789012 0 1 2 3 4 5 6 7 8 9 0 1 0 0 1 2 3 4 5 7 1 2 3 4 5 0 12345 67890 5
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 en-coded 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 combi-nations. The original Codabar specification was optimized for ink spread in press printing, re-sulting 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 char-acter 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 in-cludes all of the standard uppercase alpha-numeric keyboard characters plus the control and special characters. Subset B includes all of the standard uppercase alpha-numeric key-board characters plus lower case alpha and spe-cial 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 struc-ture 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
di-mensions has fueled the popularity of Code 128. It is being specified for a number of appli-cations, 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 limi-tations 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 en-sured. The AIAG-B3 shipping label is an excel-lent 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 Identi-fier characters, the system knows what infor-mation 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 en-coded in an X-Y matrix.
STACKED CODES
PDF417, Code 49 and Code 16K are exam-ples of stacked symbologies. The most popular of these is PDF417, developed by Symbol Tech-nologies, Inc. in 1990. 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
scanner must be able to determine when it has crossed a row boundary and “stitch” the sym-bols together. A high density PDF417 symbol can encode 500 characters per square inch of ASCII data and has a selectable security level. At the highest level, half the symbol can be missing and still be decodable. PDF417 uses “shift” characters to select a character set, much like Code 128.
Reading a stacked symbol requires a scanner that can either image the entire symbol or can raster scan the symbol and “stitch” the results together. This increases the cost of the scanner as hand scanning is not possible and laser beam scanners must raster the scan pattern.
PATTERN CODES
Whereas stacked codes are two dimensional in nature by virtue of the vertical stacking of horizontal rows of bar codes, pattern codes use the location of an information bit in a matrix to encode the data. As such, they do not techni-cally fit into the “bar code” category. They are capable of extremely high information densi-ties, where they are limited only by the ability of the printer to accurately print and place the dots and the resolution of the scanner. The two most successful of the pattern codes is Maxi-code, developed by UPS for package marking, and the Data Matrix code.
Data Matrix is a binary code that encodes formation in a checkerboard pattern with dark and light cells. The contrast between cells can be as low as 20%, allowing it to be printed with chemical or laser etch processes on
unconven-tional substrates. It can be scaled to a density of 2,334 characters per sq. in. with a sufficiently high resolution printer. Data Matrix is most of-ten read with a CCD imaging scanner.
Maxicode was developed for sorting and tracking packages. It is a matrix of hexagonal cells with a bullseye in the middle to assist the scanner in locking on the image as the package moves down a conveyor. Maxicode is a fixed, 1" x 1", 100-character code. Its structure does not lend itself to linear scanning and is most often read with a CCD imaging scanner.
HRI AND 2-D CODES
Standard linear bar codes make provision for a representation of the encoded data in Hu-man Readable Interpretation (HRI) form. The HRI requirement is a “safety net” provided for the system. If a symbol cannot be read by the scanner, the operator has the option of entering the data manually via a keypad. The new 2-D symbols make the HRI concept unrealistic. The character densities of these symbols makes it impractical to reprint the information in human readable form. The HRI information would oc-cupy much more space than the symbol, thereby defeating the purpose of high density symbols.
Symbology
Specifications
Since we are concerned with both printing bar code symbols and reading them without in-troducing any errors, the specifications for
vari-2-D Bar Codes
PDF417 Maxicode
ous symbologies allow for tolerances in both the process of printing and reading. Some of the allowable tolerances are allocated to the printing process and some to the reading pro-cess. If a symbol is “in-spec,” it simply means that the image representation of the symbol as printed on the substrate is within the limits al-lowable. The tolerances relate to such factors as the reflectivity of the spaces versus the bars and the ratio of the wide to narrow bar/space measurements.
Being able to read a bar code symbol with a scanner is not an acceptable method of deter-mining if it is within the allowable tolerances. A very poor quality symbol may possibly be read with a high performance scanner, but in this case the scanner is allowing the symbol to
in-fringe upon the tolerances reserved for the scanning system. Another scanner, or even the same scanner with a different operator, might not be able to compensate for this lack of sym-bol quality, rendering the symsym-bol unusable. For this reason, the standards will spell out the minimum acceptable levels of contrast, reflec-tance and other critical print quality measure-ments. They also specify how these measurements are to be made.
The specifications for all of the bar code symbologies listed here are maintained by the Automatic Identification Manufacturers (AIM) trade association in the form of a Uniform Sym-bol Specification. The exception is the UPC symbol which is controlled by the Uniform Product Code Council.
Perhaps as important as the type of printer used is the consideration given to the design and construction of the label itself. Again, this should be the subject of a specification, espe-cially if you are expecting someone else to print the label for you. Most major companies have developed bar code labeling specifications to which they expect their suppliers to conform. If a shipment is received without a label or with one that does not meet the specification, the shipment may be rejected and, worse yet, a fine imposed on the supplier. A good label specifica-tion should, at a minimum, specify the follow-ing information:
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The physical size and construction of the label.•
The environmental specifications.•
The symbology(s) to be used along with the technical specifications for the sym-bol.•
The number, size, position and orienta-tion of the fields along with the data to be contained in each.Design
The design of the label is critical. If you are dealing with a simple item identification label containing nothing but a single bar code and its human readable information, then it is rela-tively simple. However, here you still may be required to make a tradeoff on whether to print the label horizontally across the label using a wider web printer or to print it vertically down the length of the label with a smaller web printer running slower. Complicating the deci-sion would be the addition of images such as company logos and fancy human readable
printing such as commonly found on retail bar code tags.
SIZE
The physical size of the label must be within reasonable limits. One too small is difficult for klutzy fingers to position precisely, while a very large label is almost impossible to apply with-out creating a wrinkle (which can destroy the readability of the bar code). As a general rule, labels as small 1/2" high by 1" long and as large as 5" high by 7" long can be applied manually without too much difficulty.
MULTIPLE BAR CODES
As soon as more than one bar code is in-cluded on the label, the problem of which one is read by the scanner must be addressed. This can be solved by using different symbologies for each bar code or by including a “Data Identi-fier” character at the start of the data string. The two symbology approach is generally discour-aged, since it requires two symbologies with similar structures and data encoding capabili-ties. Another way to separate two different bar code symbols is to place them at right angles to each other, but problems appear again when more than two symbols are needed.
Multiple bar code labels must face another problem, that of how the operator knows which symbol was scanned. This is not difficult if a hand wand scanner is used, but a moving beam laser operator has no control over the horizon-tal scanning of the beam, just how it is vertically positioned. It is difficult to control which sym-bol is being read if they are both placed side by side. In this case, stacking the symbols verti-cally, will solve the problem since the beam can never cut through more than one complete
symbol. All of these problems can be eliminated by use of industry standard Data Identifiers to identify the data contained in the symbol.
The placement and orientation of the fields can have a significant effect on the success of a bar code system. If there is information on the label that must be read by an operator, then it should be presented in a highly visible area in a font that will maximize readability. Bar code fields should be easily identified by the opera-tor who must do the scanning.
QUIET ZONE
One of the most common mistakes made in label layout is the failure to include sufficient Quiet Zones at the
begin-ning and end of the bar code. This is blank space free of any printing or marks. It is needed by the decoder to establish the end points of the symbol. While the decoder may be able to resolve a Quiet Zone that is at least 10 times the smallest bar dimension, the Quiet Zone should never be less than 0.25". Even at that size, hand scanning with a wand is difficult because hand mo-tion is very erratic at the be-ginning and end of the scan. Placing the bar code too close to the edge of the label violates the Quiet Zone rule even if the label is placed on a white surface. The scanner may detect the raised label edge as a non-reflective bar.
Design
Software
After deciding what the label should look like, the next problem encountered is how to create it. There are two options, you can eitherwrite your own program or use a software pack-age to do it for you. If the number of different label designs is small, and the data on them is minimal, it is relatively easy to write a small program to do the job. The Basic program shown in the illustration will print the example label shown on a SATO M-8400RV printer. It has only three fields, one a bar code with HRI information printed below it and two text fields surrounded by a box. However, the day when the process consisted of sending a line of char-acters down to a text printer to be printed upon a receipt of a carriage return is long gone. Now you have to specify the font, how large it is, where the characters are to be placed, the ori-entation of the field, what type of bar code, etc.
The AIAG shipping label illustrates the prob-lem of complex label designs. It typically con-tains 29 fields that must be separately programmed along with eight border lines. Also, the information contained in the fields can, and probably will, vary from label to label. Even if we manage to get all of the fields pro-grammed correctly, we still have to find a way to easily enter the variable data into the fields without writing a new program each time. We are talking serious programming here with “GO TO” statements, “LOOPS” and other esoteric jargon.
It is obvious that we need something to insu-late us from this process. A label design and software package is in order. The definition of a “good” label design package depends upon the label to be designed. For a simple layout, a ba-sic text-based program asking you to enter co-ordinates and information with a menu driven screen is acceptable. However, more complex labels are difficult to visualize using this
method. A WYSIWYG screen layout program is preferred.
One caveat is in order, even though a label design program allows you to do all sorts of fancy things, unless the capability is needed, it can end up complicating your life. The only per-son that becomes proficient in using a compli-cated label design program is one that uses it a lot. This is not the normal case in the industry, where it is more likely that a few standard la-bels will be designed and used over and over. For this reason, an intuitive design program is desired, one where you do not spend a lot of time trying to understand how to use the pro-gram. A Windows based program would be a good choice, since it has a user interface that is familiar to most people. A Windows design screen from SATO’sLabel Wizardprogram illus-trates the advantages. It provides a user-friendly interface that insulates the user from the intricacies of the design process.
A demo copy ofLabel Wizardcan be down-loaded free from the SATO internet web site (http://www.satoamerica.com). This is a com-plete functional version of the program and contains all of the features and capabilities of
Label Wizardexcept for production printing. All of the label formats designed with this version can be used if a decision is made to upgrade to the full production version ofLabel Wizardat a later date.
Printing
Most label design programs will allow you to print labels directly from the program. Some-times this is not the way to go. If the operator only needs to print labels, there is no need to supply access to the design part of the program. As a matter of fact, it is probably desirable to limit access since the temptation to “improve”
the design is eliminated. Being able to break the print portion out into a print only stand-alone program (referred to as a Run Time program) is the best solution. The operator then has to se-lect the right label design from a list and iden-tify the source of the data for the fields.
If the labels are to be used in a production environment, the ability to automatically ac-cess external database files for the contents of variable fields is a necessity. By defining the field as a variable and tying it to a database, the information can be automatically placed in the field at the time of printing. This allows all data-base management to be confined to the primary database and any updates or changes automati-cally incorporated into the label without having to modify the label printing job. The database types can be supported by the program directly or indirectly through the new Microsoft ODBC (Open Database Connectivity) specification.
WINDOWS PRINTER DRIVER
Sometimes it is desirable to be able to print directly to a bar code printer from a standard Windows application program. To do this you need to load the printer as a standard Windows printer. A Windows Printer Driver is available for many of the more popular bar code printers. Windows drivers for SATO printers are avail-able free of charge from SATO. These drivers support all of the bar code symbologies resident in the SATO printers. This allows precise con-trol of the bar code to ensure that it is printed within specifications.
One of the primary disadvantages of using a Windows Driver is transmission time. All True-Type®fonts are transmitted to the printer in a graphics format, i.e. instead of sending a character code to the printer, the actual bit map character is sent. While this increases the ver-satility and selection of fonts, it greatly in-creases the amount of data to be transmitted to the printer. For most printers, this would cause an objectionable delay in label production time. However, the new enhanced SATO print-ers (the CT Series and all “e” printprint-ers) with their new high-speed interfaces and thrid gen-eration RISC processors, can easily accomodate large data transfers without impacting label production time. With these printers, the data transmission and imaging time is minimal, re-sulting in extremely high through-put. A com-parison report illustrating these speed advantages, Achieved Label Print Time, can be downloaded from the SATO America web site at http://www.satoamerica.com.
USING TrueType
®BAR CODE FONTS
Bar codes can be printed from standard Win-dows applications using bar code TrueType® fonts, of which a number are available from dif-ferent sources. These can be used successfully
with the SATO Windows Printer Driver, but ex-treme care must be used to ensure that readable bar codes are printed. There are several areas in which careful attention must be made:
