Abstract:
An impact printer such as a line printer having a base with a hammerbank mounted on the base driven for reciprocal movement. The hammerbank has a plurality of hammers with printing tips formed on frets in two longitudinally oriented rows defining an upper row and a lower row. A permanent magnet with pole pieces retains the hammers until a coil overcomes the magnetic retention. A print ribbon is impacted by the printing tips of the impact printer such as a line printer against a print media. The print ribbon has a first longitudinal high strike zone of ink of greater print yield with a low strike zone of lesser print yield on either side of the first zone. The print yield can be a factor of ink viscosity, pigment content, fabric content, fabric composition, or dye features.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The field of this invention is within the impact printer field and in particular, the line printer field directed toward using a line printer having multiple hammers with tips that strike a ribbon that impacts an underlying print media such as paper. The line printers are such where they have a number of hammers on the hammerbank which are held by a permanent magnetic force and then released by electromagnetism. When released, the hammer tips strike a ribbon which impacts the underlying media to be printed upon. During the striking of the ribbon, the ink is depleted from the ribbon in a manner whereby variances of appearance of the printed product can be apparent. 
     2. Prior Art 
     The prior art with regard to line printers incorporates various line printers having singular rows of hammers with printing tips in a hammerbank. These rows of hammers in a hammerbank are released from permanent magnetic retention by an electromagnetic coil. The hammer tips when released proceed toward an inked ribbon for impacting against a media to be printed upon. 
     Recently, a new hammer orientation has been developed wherein a hammerbank having dual hammers incorporates an upper and lower set of hammers. These upper and lower sets of hammers are released so that the ink or print ribbon is impacted by two hammers in an upper and lower or duplex banked mode. This dual print activity by the hammers puts a double load on the capacity of the ink or print ribbon for providing ink. To this extent, the capacity of the ink ribbon if it is consistent through the ribbon causes variances because of variously differently oriented strike zones. 
     The term banding is a term wherein one of two printed lines will be darker on the right side than on the left. The next line will be darker on the left and lighter on the right. 
     The two rows of hammers which are on top of each other having an upper and lower set of hammers are spaced approximately one sixth of an inch apart. They simultaneously print adjacent rows, effectively doubling the through put of the printer. 
     The printing is by a printed dot when the hammer strikes against an inked ribbon leaving a dot on the paper or underlying media. A one inch or wider inked ribbon reciprocates or translates continuously between the hammers and the paper or media at an incline. This incline is to allow for greater ribbon use since the incline causes the ribbon to cross the total number of hammers. The incline helps to eliminate a concentration of the hammers impacting the print ribbon in one particular area such as down the middle. 
     A heretofore unsolved problem with the dual row arrangement of hammers is that the center area across the ribbon width of the ribbon is generally struck twice or at least more than once during each pass of the ribbon. To the contrary, the outer boundaries are only struck once or less. The result is that after a relatively small number of printed pages a light and dark pattern of printed lines appears. 
     For instance, one of the two printed lines such as that printed by the upper row of hammers will be darker on the right side than on the left. The next line of print as printed by the lower row, will be darker on the left and lighter on the right side. This particular phenomena or effect is known as banding. 
     A second lesser disadvantageous effect occurs which is addressed by this invention. This second effect is that the printing density varies from darker appearances at the edges of the page, to lighter appearance toward the middle of the page. This is due to the high ink concentration of the unused edges of the ribbon. These boundaries are necessary to insure that in all cases the end hammers always strike inked ribbon. Since the ink in these boundary areas does not get removed from the ribbon as the result of hammer strikes it tends to defuse into the adjacent area. This particular characteristic is referred to as a diffusion effect. The diffusion effect causes the print at the edges as previously stated on the paper to be darker than the center. This is independent of the banding effect. 
     The diffusion effect can be worse on the left side of the paper than on the right side. This is due to the effect of gravity on the ink in the ribbon. The reason is that the left side of the printed page derives its ink from the lower left portion of the inclined ribbon. 
     The invention hereof tends to overcome the foregoing deficiencies of the prior art by providing for an ink or print ribbon which has a variable characteristic. When being struck, it compensates for the fact in certain portions the ribbon is being struck twice as much or more than the other portions. These particular portions are generally in the central area where the larger amount of strikes take place. 
     SUMMARY OF THE INVENTION 
     In summation, the invention reduces banding, diffusion, and gravity effects by locating inks with different printing yields provided by varying concentrations, pigment contents, or viscosity on different portions of the ribbon such as in the longitudinal central portion and the edge portions in such a manner as having a greater printing yield in the middle and a lesser printing yield on the edge portions. 
     More specifically, the highest ink concentration or print yield is located in the middle of the ribbon or the longitudinal center. This generally corresponds with a double or more than one strike zone. Proportionally ink having a lesser yield is located at the upper and lower boundary areas which are used less. These longitudinal boundary areas are such where the lower ink yield provides for the lesser hammer strikes which can be in a range of one half the hammer strikes as received in the longitudinal center of the ribbon. In this manner, the ribbon will be located with appropriate ink yields on different portions based upon consumption, thereby reducing the banding, diffusion, and gravity effects. 
     It has been found that this is extremely helpful with regard to impact printers and particularly to double row line printers where hammers are queued or banked above each other. The net result is an. improved printout which can be seen hereinafter in the specification hereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a perspective view of a fragmented portion of a line printer having paper or other print media passing through the printer. 
     FIG. 2 is a front elevation view showing the print ribbon of this invention passing across the double bank of print hammers. 
     FIG. 3 is a perspective fragmented view of the hammers and print mask of this invention along lines  3 — 3  of FIG.  1 . 
     FIG. 4 is a sectional view along lines  4 — 4  of FIG.  3 . 
     FIG. 5 shows a view of the improved text and printing when using this invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a perspective view of a line printer employing this invention. In particular, the line printer incorporates a base  10  which can be part of a stand or part of a mobile or desktop unit. The printer has a pair of hubs  12  and  14  which respectively receive spools  16  and  18  of print ribbon. The spools  16  and  18  that receive print ribbon have the print ribbon wound therearound in a consistent manner to be driven in a reciprocating, transitional, or traversing manner back and forth across the hammerbank. The ribbon moves from one spool  16  to the other spool  18  in a winding and unwinding manner so that it traverses backwardly and forwardly for the substantial length of the ribbon in front of the hammerbank. In this particular case, the spool  16  is being shown emplaced upon the hub  12 . 
     The ribbon is shown specifically as a ribbon  20  being fed between the two respective spools  16  and  18 . The ribbon  20  is fed around a ribbon guide  22  on either side. The ribbon guide  22  also has a sensor to show when the ribbon has passed a certain point and is to be reversed. 
     The printer incorporates a paper feeder generally shown as paper feeder  24  which feeds paper  26  across the throat of the printer for printing by the hammerbank hammer tips impacting the ribbon  20 . A knurled knob  28  is provided in order to hand feed the paper  26  across the face of the print head or hammerbank. Tractors are provided which feed the paper at the edges which have been provided with punched openings to be fed by the protuberances of the tractor moving the paper  26 . 
     The print ribbon  20  is such where it passes over a ribbon or print mask shown in FIG.  2 . The ribbon or print mask shown in FIG. 2 is shown as ribbon mask  30 . The ribbon mask  30  has a plurality of openings  32  on an upper portion and  34  on a lower portion through which hammer tips extend. The ribbon  20  is angled or inclined with respect to the alignment or longitudinal relationship of the line of print hammers. The angle of inclination which is shown as angle A is approximately 2.70° from the longitudinal axis of the line of print hammers. The angle can vary depending upon the number of hammers and spacing. 
     The ribbon  20  when traveling across the print hammers traverses multiple segments of the ribbon backwardly and forwardly over hammer tips. If the ribbon were not angled, it would create a situation wherein all the striking hammer tips striking through the ribbon mask openings  32  and  34  would strike in one particular width area. For instance, it might be in the center or on the edges depending on where the ribbon  20  were oriented. 
     The strike zone of a ribbon when angled across a great number of hammerbank print tips extending through the print mask  30  provides for an angular striking across the width of the ribbon as it traverses backwardly and forwardly. This accomplishes a greater striking of the ribbon  20  except in a particular outer no strike zone. 
     Looking more particularly again at FIG. 2, it can be seen that this no strike zone is on the peripheral edges namely no strike zone  42  on the upper no strike zone and no strike zone on the lower no strike zone  44 . These longitudinal no strike zones  42  and  44  are emplaced in order to avoid the hammers impinging against the areas that are extremely marginal. 
     A low or single strike zone  46  in the upper portion and  48  in the lower portion allows for a low or single strike of the hammer tips along the longitudinal length inasmuch as the ribbon does not traverse and incur that area of the double hammers when it is placed at the angle A. 
     Finally, the high or double or more than one strike zone  50  is shown which is approximately twice the width of each of the low or single strike zones  46  and  48 . This accommodates the double hammer tips throughout the entire zone  50 . 
     In order to understand the characteristics of the print mechanism, it can be seen that the ribbon mask  30  is shown in FIG. 3 connected to a hammerbank  60 . The hammerbank  60  is generally made of a solid material and can be milled, cast, or formed in any particular manner. The hammerbank has a slot  62  that receives a circuit board  64 . The circuit board  64  mounts drivers and controls as well as logic to drive the hammers which will be detailed hereinafter. 
     The hammerbank  60  with the hammers connected thereto incorporate permanent magnets  68  and  70 . The permanent magnets  68  and  70  draw in the hammers to their magnetic pole piece ends. They are then released through a change of magnetic retention force through a series of coils in relationship to each hammer which will be seen in greater detail in FIG.  4 . 
     Again, looking more specifically at FIG. 3 it can be seen that hammers in the upper section namely hammers  74  are shown in the upper bank while hammers  76  are shown in the lower bank. These respective hammers  74  and  76  have tips or pins respectively  78  an  80  that pass through the openings  32  in the upper portion and  34  in the lower portion of the ribbon mask  30 . 
     The hammers  74  and  76  are formed on frets  82  and  84  respectively on the upper and lower hammerbanks. These frets  82  and  84  are such wherein they are milled or formed. The hammers  74  and  76  thereafter are cut thereon or formed such as by an electro discharge cutting or milling operation. 
     FIG. 3 shows the ribbon  20  superimposed in a fragmented form in dotted configuration over the openings  32  and  34  of the print ribbon mask  30 . The print ribbon mask is seen as ribbon mask  30  in FIG. 4 with the openings  32  and  34 . 
     Looking more particularly at FIG. 4 it can be seen that the hammerbank body  60  has been shown with the permanent magnets  68  and  70  in respective slots in the upper and lower hammerbank portions. The permanent magnets  68  and  70  are mounted and magnetically connected to pole pieces  90  and  92 . These form a magnetic loop through the ends of the pole pieces. 
     The pole pieces  90  and  92  are wrapped with pairs of coils. Pole piece  90  has coils  96  and  98  wrapped therearound while pole piece  92  has coils  100  and  102  wrapped around the ends thereof. The coils  96  through  102  are connected to electrical connectors or terminals. The upper set of coils  96  and  98  are specifically connected to connectors  106 . The coils  100  and  102  have the coils connected to a second set of connectors  108 . These connectors  106  and  108  are connected to the circuit board  64 . Circuit board  64  has transistor drivers thereon which provide power through a firing sequence of the coils  96  through  102  which causes the hammers of the hammerbank to be released from their magnetic retention. The coils  96  through  102  create an electromagnetic field that overcomes the permanent magnetism of the magnets  68  and  70 . 
     When looking at the hammers, it can be seen that the upper hammers  74  have a pin or tip  78  extending therefrom. The lower hammer  76  has a pin or tip  80  extending therefrom. These pins pass respectively through the openings  32  and  34  of the ribbon mask  30 . The hammers are mounted with their frets  82  and  84  as shown in the general configuration provided in both FIGS. 3 and 4. 
     When the permanent magnetism of magnets  68  and  70  is overcome by the coils  96  through  102  causing a release thereof, the pins  78  and  80  fire through the openings  32  and  34  of the ribbon mask and impinge against the ribbon  20  passing thereover. When striking against the ribbon  20  passing thereover, they strike against a media such as paper  26  passing through the printer and provide for a dot thereon. 
     The ribbon  20  has been shown superimposed in dotted form with the respective portions of this invention that will be explicitly detailed further hereinafter. 
     Again, looking at the ribbon  20  as shown in FIG. 2 it can be seen that there is a double, high, increased, or multiple strike zone  50 . Low, decreased or single strike zones  46  and  48  bound each side of zone  50 . De-minimis or no strike zones  42  and  44  are at the peripheral edges. 
     The objective of the invention is to minimize banding, diffusion, and gravity effects by locating inks with different print yields in the respective high or double strike zone  50  and low or single strike zones  46  and  48 . The highest ink load or high print yield ink is located in the middle section of the ribbon namely the high or double strike zone  50 . 
     Proportionally, less ink and lower print yield is required in the low or single strike zones  46  and  48 . These are the respective upper single striking zone and lower single striking zone as well as the de-minimis or no strike zones  42  and  44 . This causes the ribbon to be located with appropriate inks for different printing yields on different portions based on consumption and decreased yield. This minimizes the banding, diffusion, and gravity effects. 
     The areas of the high or double strike zone  50  and the low or single strike zones  46  and  48  have been delineated generally as the high or double strike zone  50  receiving twice as many impacts as the low or single strike zone. However, it should be understood that when the hammers are not firing because of the orientation of the dots, that this can vary from outside of a two to one relationship. The strike zone relationships can be wherein the strikes take place at a lesser or higher ratio than two to one depending upon the type of printing and the specific alpha numeric or bar code or other orientation that is to be printed. In effect, the duty cycle of the hammers impinging the ribbon could vary with respect to the two zones  46 ,  48 , and  50  and not be confined strictly to the low or single and high or double characterizations. However, as a general rule the average of strikes between the multiple, high, or double zone  50  and the low or single zones  46  and  48  will be approximately on a two to one ratio if the printing between the zones is within the realm of generally analogous characters or print forms. 
     When referring to print yield, the reference is to the number of strikes, or impacts by the tips  78  or  80  against the print ribbon  20  and the attendant or related print output or printing life. For example a ribbon having twice the print yield for the high, double or multiple strike zone  50  would be able to print approximately twice as much as the low or single strike zones  46  and  48  without significant deterioration of print quality. In effect, the impacts on the ribbon  20  can be approximately or substantially twice as great in high or double strike zone  50  with a print yield substantially or approximately twice as great as the lesser print yield of the low or single strike zones  46  or  48 . The print yield is calculated to be in proportion to the number of impacts or strikes so that the print remains substantially uniform. 
     The ink compositions of the present invention are generally the same compositions and components used in conventional printer inks. These generally can include a vehicle or carrier and at least one coloring agent. Other materials are often included such as for example, a dispersing agent, a viscosity adjusting agent, a humectant, an emulsifying agent or surfactant, and a drying-preventive agent, an infrared absorptive dye and/or an antifungal agent. 
     With respect to the coloring materials, these can include various kinds of organic or inorganic pigments for example, those of the azo series, phthalocyanine series, quinacridone series, anthraquinone series, dioxazine series, indigo series, benzidine series, thioindigo series, perinone series, perylene series, isoindolenone series, titanium oxide, cadmium series, iron oxide series, carbon black, and the like. 
     Dyes characterized by satisfactory permanence in spite of exposure to light, air and normal handling are referred to as “fast” dyes; others are “fugitive.” Most dyes are synthesized from the aromatic hydrocarbons (coal-tar dyes) and related materials. Dyes are classified according to chemical composition and also according to the way in which they behave during application. The most important chemical types are the azo, anthraquinone, sulfur, indigoid and stilbene dyes. The chemical classes of coloring matters and their arrangement according to chemical structures have been designated numerically according to the “Colour Index” (1957 revision) as follows: 
     
       
         
               
               
               
             
           
               
                   
                   
               
               
                   
                 Chemical Class 
                 Colour Index 
               
               
                   
                   
               
             
             
               
                   
                 Nitroso 
                 No.10000-10299 
               
               
                   
                 Nitro 
                 10300-10999 
               
               
                   
                 Monazo 
                 11000-19999 
               
               
                   
                 Disazo 
                 20000-29999 
               
               
                   
                 Trisazo 
                 30000-34999 
               
               
                   
                 Polyazo 
                 35000-36999 
               
               
                   
                 Azoic 
                 37000-37999 
               
               
                   
                 Stilbene 
                 40000-40999 
               
               
                   
                 Diphenylmethane 
                 41000-41999 
               
               
                   
                 Triarylmethane 
                 42000-44999 
               
               
                   
                 Xanthene 
                 45000-45999 
               
               
                   
                 Acridine 
                 46000-46999 
               
               
                   
                 Quinoline 
                 47000-47999 
               
               
                   
                 Methine 
                 48000-48999 
               
               
                   
                 Thiazole 
                 49000-49399 
               
               
                   
                 Indamine 
                 49400-49699 
               
               
                   
                 Indophenol 
                 49700-49999 
               
               
                   
                 Azine 
                 50000-50999 
               
               
                   
                 Oxazine 
                 51000-51999 
               
               
                   
                 Thiazine 
                 52000-52999 
               
               
                   
                 Sulfur 
                 53000-54999 
               
               
                   
                 Lactone 
                 55000-55999 
               
               
                   
                 Aminoketone 
                 56000-56999 
               
               
                   
                 Hydroxyketone 
                 57000-57999 
               
               
                   
                 Anthraquinone 
                 58000-72999 
               
               
                   
                 Indigoid 
                 73000-73999 
               
               
                   
                 Natural 
                 75000-75999 
               
               
                   
                   
               
             
          
         
       
     
     The vehicle or carrier can include, for example, organic acids such as aliphatic carboxylic acids such as lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, oleic acid, adipic acid, citric acid and ascorbic acid; aromatic carboxylic acids such as benzoic acid, salicylic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthoic acid, gallic acid and tannic acid; and sulfonic acids such as dodecyl sulfonic acid and alkylbenzenesulfonic acid. 
     Various oily substances can also be used as the dissolution medium for the dye or the dispersion medium for pigment. Examples of the oily substances include among others: vegetable oils such as rapeseed oil, castor oil and soybean oil; animal oils such as beef foot oil; higher fatty acids such as isostearic acid and oleic acid and mixtures thereof. 
     Typical examples of the surfactants are sorbitan monoleate, sorbitan trioleate, polyoxyethylene sorbitan monooleate, and polyoxyethylene monolaurate. 
     Examples of humectants include among others alcoholamines (triethanolamine and similar alcoholamines), fold  14  alkylamines (triethylamine and similar alkylamines) and aliphatic lower alcohols (ethanol, propanol, hexanol and similar alcohols); examples of emulsifying agents include among others aromatic polyglycol ether, alkyl aryl polyglycol ether and sorbitan monooleate; and examples of drying-preventive agents include among others alkyl naphthalene sulfonate and alkyl aryl sulfonate. 
     The viscosity can be adjusted in various ways as each ingredient contributes to the final viscosity. In addition to the vehicle or carrier, other ingredients can be added which can further adjust the viscosity. 
     Examples of viscosity-adjusting agents include among others mineral oils such as motor oil; and synthetic oils such as olefin-polymerized oil (e.g. ethylene hydrocarbon oil, butylene hydrocarbon oil, and the like), diester oils (e.g. dioctyl phthalate, dioctyl sebacate, di(1-ethylpropyl) sebacate, dioctyl azelate, dioctyl adipate, and the like), and silicone oils (e.g. linear dimethyl polysiloxane having a low viscosity, and the like). Mixtures of two or more kinds can be used. 
     Examples of the pigment-dispersing agent include among others sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitan alkyl ethers, glycerin fatty acid esters, propylene glycol fatty acid esters, polyethylene glycol fatty acid esters, polyoxyethylene alkyl ethers, hardened castor oil derivatives and polyoxyethylene castor oils. One or a mixture can be used. 
     The ribbon is commonly formed of generally woven cloths including for example, fibers such as nylon, polyester, cotton and silk. The thickness of the ribbon substrate can vary but is commonly from about from about 80 to about 140 .mu.m. Generally, the ink composition is contained in an amount of about 8 to about 21 g/m.sup.2 into the substrate. 
     The inks can be made in a conventional manner by thoroughly mixing together the ingredients in any convenient manner known to those skilled in the art. The resulting mixture can be adjusted for the desired viscosity as described herein and applied to the ribbon to the desired thickness in any convenient manner. 
     Thus, the basic characteristics of ink and their ingredients or portions of the compounded ink relate firstly to a vehicle or carrier which can be a fatty acid such as oleic acid or a similar vehicle. Secondly, the ink can include pigments which can be solid such as carbon black or other coloring materials which will affect the infrared reading characteristics of the printed material. The infrared characteristics are important with regard to certain bar code scanners. Thirdly, supplementary additives can be a number of things but each has its specific purpose. For example, these supplementary additives in the way of dyes can be such as induline, azine, methyl violet, or nigrosine, or other dyes which can adjust viscosity and flow properties. 
     Differences in ink properties and attendant print yields can be a result of variations in the foregoing three basic ingredient groups. Although, other ingredients and compounds can be utilized, the foregoing constitutes the general nature of the materials that result in variations in the print ribbon characteristics and corresponding print yield. 
     The function of the vehicle or carrier is to act as a carrier for the pigment and as a binder to affix the pigment to the printed surface of the paper or other media. The nature of the vehicle or carrier is such where its viscosity determines the flow characteristics of the ink and attendant print yield. Viscosity fundamentally is the liquid&#39;s resistance to flow in the form of the carrier, the higher viscosity, the less resistance to flow. Ink ribbons of high viscosity ink have a longer life or higher print yield than lower viscosity ink because the high viscosity ink restrains the amount of ink transferring to the media upon impact. 
     The pigments are usually finely divided solid materials that give inks color and opacity or transparency along with other important qualities. Such pigments can be in the form of carbon black, lamp black, or other colored particulate materials. High pigment content has a greater tendency to place the ink on the paper which offsets or lowers the print yield. It should also be understood that the pigments generally do not chemically bond to the carrier but rather form a relationship on the basis of van der Waal&#39;s forces. In effect the higher the ratio of pigment in the ink, the lesser the life or print yield. 
     The ribbon  20  of this invention is composed of three inked or relative print yield portions. This can be seen in FIG.  2 . The outer longitudinal portions or boundaries have a comparatively low ink life or print yield namely those portions which are the low or single strike zones  46  and  48  and the no strike zones  42  and  44 . These specifically consist of ink having a low concentration, high pigment, or low viscosity which has a relatively low character, or print yield. It has been found in the art that a high pigment content creates a situation wherein the ribbon does not last as long or has a lesser print yield because of the pigment itself being displaced from the carrier. 
     The longitudinal middle portion of the ribbon  20  namely the high or double strike zone So is composed of ink with higher character or print yield. 
     By carefully formulating ink concentration, pigment content, or ink viscosity, the ribbon is able to maintain appropriate ink loads or yields on the high or double strike zone  50  and the low or single strike zones  46  and  48 . The result is to create a print yield or life approximately twice as great in the high or double strike zone  50  as that of the low or single strike zones  46  and  48 . 
     As to the formulations, concentrations, viscosities, and general characteristic of the inks, they can vary within the realm of variable print yields. The main criteria is that the highest ink load or print yield is to be located where the highest concentration of impacts occur. 
     Proportionally less ink or characteristic print yield is located in the outer portions of the ribbon namely those portions  46  and  48 . These respective zones  46  and  48  which are struck generally only singularly, do not require as much ink or print yield. Accordingly, this eliminates the darkness and lightness between the respective low or single strike zones  46  and  48  and the high or double strike zone  50 . As can be appreciated, other configurations of strike zones would require different concentrations of ink or print yields. For instance, if the ink striking zones were to be differently oriented as to perhaps multiple banks of hammers in the outer zone as opposed to the inner zones due to canting or stepped hammer locations in side-by-side relationship, then the orientation of ink concentration or print yield would then have to change. In this manner, the ribbon will be located with appropriate inks or ink yields on different portions based on consumption thereby minimizing the banding, diffusion, and the gravity effects. 
     The three basic ingredients or classifications of ink are the carrier or vehicle (oleic acid), the pigments (solids), and supplementary additives. These generally are such wherein the carrier can control the viscosity, the pigment can control the amount of ink being transferred from ribbon to paper and such additives as nigrosine, methyl violet, or other dyes can also control part of the nature of the ink. The foregoing in concert control the print yield of the ink. 
     Viscosity is a very important facet with regard to the flow of the ink. To this extent, it is such where it has greater variability and concentration elements with regard to the overall nature of it to provide for more discrete control and attendant print yield. Pigment in certain cases, because of the impacts causing the pigment to be driven from the carrier or the ribbon, creates a situation wherein the pigment when in greater concentration actually lessens the life or print yield of the ribbon. This is because the pigments are finely divided solid materials that give the inks the color and opacity or transparency depending upon the particular concentration. High pigment content has a greater tendency to displace the ink to the paper which offsets the character or print yield. 
     It has been found that with regard to viscosity the respective ink characteristics between the low or single strike zones  46  and  48  and the high or double strike zone  50  are such wherein the range can be 2700 centipoises (CPS) for the low or single strike zones  46  and  48  and 3400 CPS for the high or double strike zone  50 . Viscosities can also range from 500 CPS for the low strike or single strike zones  46  and  48  up to 4200 CPS for the high or double strike zone  50 . 
     As to ink concentration, with regard to overall concentration of ink on the ribbon, the low strike or single strike zones  46  and  48  can range upwardly from approximately 8%. The high strike or double strike zone  50  range can be as high as 28%. By concentration of ink, it is meant the overall concentration of ink on a given ribbon when compared to the ribbon without ink. This is the percentage of weight of the ink on the ribbon. In effect, concentration is the percentage of ink on the ribbon when compared to the uninked ribbon. 
     The pigment content which can be formulated from lamp black or carbon black can be upwards from 0% for the high or double strike zone  50 . The low or single strike zones  46  and  48  can have pigment content up to 40%. This is because of the fact that as the concentration of pigment is increased, it actually decreases the overall life or print yield of the low or single strike zones  46  and  48 . This is due to the fact as previously noted that it becomes displaced more readily. The relative characteristics of the ink ribbon are modified proportionally between the high or double strike zone  50  and the low or single strike zones  46  and  48 . 
     Aside from pigment content, viscosity, and dye yield or content, other factors can affect print yield. For instance, the total percentage of ink concentration or weight of ink on the ribbon changes the print yield as previously discussed. 
     Fabric content or density of fabric also is a factor. For instance, a more dense fabric will retain more ink and provide a greater print yield. Thus for the high or double strike zone  50 , the ribbon can be provided with a band or median longitudinal segment of greater fabric density. In such a case the relative density of the low or single strike zones  46  and  48  can be of a lesser fabric density. 
     The fabric material can also be varied. For instance, the lower yield zones  46  and  48  can be made from strips having less ink retention or absorbency. Thus a natural fabric or blend can be used for higher print yield in zone  50  and a less absorbent synthetic material for lower print yields in zones  46  and  48 . 
     The one characteristic that should be maintained is that the single or lesser strike zones  46  and  48  will have a lesser life or print yield than the double or concentrated high or double strike zone  50 . These print yields can be derived so that the ink when displaced from the two respective zones will diminish at the same rate. In effect, the net result from the foregoing print yields in each zone is to have the low or single strike zones  46  and  48  depleted as close to the same rate as the low or single or high or double strike zone  50 . Thus, as the ink is depleted at the same rate the banding appearance of the print is diminished so that variations in appearance are diminished. This provides for a consistently appearing print as to overall ink displaced and print quality on the paper, or other media  26 . 
     The result when reviewing the drawings can be dramatically exemplified in the showing of FIG.  5 . The printed text with the invention can be seen in FIG. 5 as being the “improved text with invention”. The text without the invention as known in the prior art can be seen as the “text before invention”. These two respective characteristics of appearance are dramatized in FIG. 5 to show the effect of the invention and the improvement over the prior art. 
     While the invention has been described particularly with respect to line printers, the invention is not limited thereto and is intended to be applied to any impact printer for increased print yield. 
     Various modifications of the invention are contemplated which can be resorted to by those skilled in the art without departing from the spirit and scope of the invention as defined by the following claims.