JPH02561A - Method and device for improving printing characteristic - Google Patents

Abstract

PURPOSE: To always accurately reproduce a print image showing the optimum characteristics regardless of the alteration of a substrate or a change of printing environment by controlling the respective parameters of a printing system having a direct influence upon the print image characteristics individually or in combination. CONSTITUTION: In an ink jet apparatus, a substrate having predetermined absorbability is provided and ink having a predetermined diffusion coefficient is provided and the temp. of the ink is regulated to 10-200 deg.C while the temp. of the substrate is regulated to -40-200 deg.C and the distance between a printing head and the substrate is regulated and a predetermined vol. of the ink is ejected toward the substrate at a predetermined speed from the printing head. When the hot molten ink ejected from the ink jet apparatus is bonded to the substrate, an almost circular ink dot having a predetermined diameter, tactility and durability is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to inkjet printers, and more particularly to inkjet printers in which printing is performed by ejecting ink droplets at various time intervals according to demand.

[Prior Art and Problems to be Solved by the Invention] A typical inkjet printer includes an inkjet chamber having an orifice for discharging ink droplets, and an ink supply inlet communicating with an ink reservoir. ing. In such jets, a driver is connected to the inkjet chamber, and changes in the pressurization of the driver result in the ejection of ink drops from an orifice. By changing the pressurization of the driver at the appropriate moment, an ink droplet is ejected onto a trajectory towards the appropriate substrate or target (eg paper).

U.S. Pat.
U.S. Pat. Disclosed is an inkjet device arranged in rows. The driving body is pressurized in response to an electric field selectively applied in a direction perpendicular to its longitudinal axis.

Inkzetsu, which consists of 1R1L, is a solid state at room temperature.
It uses granular ink that becomes liquid when the temperature rises. This solid particulate ink is heated in a reservoir within the printer nostem, thereby melting the particulate ink into liquid ink and maintaining the ink in a liquid state. The liquid ink thus obtained is commonly referred to as "hot melt ink."

It is important that images printed with such inks have uniformly high durability and quality. Print quality and durability are not only important for the appearance of printed images, but are also essential in some practical applications.

For example, it may be difficult for an optical character recognition scanner to recognize printed characters that have dirty, worn, or poorly defined edges. Therefore, it is essential that the edges of printed barcode lines are abrasion resistant and have sharp contours, which allows the thickness of each line and the spacing between adjacent lines to be can be determined accurately and reading errors can be avoided.

Attempts have been made to achieve these results in conventional inkjet printers by reducing the heating effects of the paper by lowering the temperature of the hot molten ink. However, decreasing the temperature of the ink affects the viscosity and surface tension of the ink. This adversely affects the ejection of ink from the printhead. In particular, as the temperature of the ink decreases, the viscosity of the ink and the surface tension of the ink generally decrease, making it difficult to form and maintain an ink meniscus at each orifice. The presence of this meniscus is important for accurate ejection of ink. Therefore, lowering the temperature of the hot molten ink alone has not been sufficient to successfully produce printing acids of consistently high durability and quality.

It is an object of the present invention to provide a printing system that consistently produces bullet images of high durability and quality.

Another object of the present invention is to provide a printing system that produces printed images that are accurately and predictably reproducible under a variety of conditions, so that the characteristics of the printed image are independent of substrate type and printer environment. The goal is to make it stable and unchanging.

Yet another object of the present invention is to provide a nostem for identifying these parameters and a system for modifying the identified parameters, individually or in combination, without significantly affecting the properties of the printed image. The purpose is to create a printed image with a

[Means to solve the problem]

In accordance with these and other objectives, the characteristics of the desired high quality and durable printed image are identified and quantified.

These characteristics include the size or diameter of the ink dots that make up the printed image, the roundness of these dots, the degree to which the ink penetrates below the surface of the substrate, and the degree to which the ink remains on the surface of the substrate (here and below). Now let's consider the tactile sensation (ta) of the printed image.
ctility)) and the printed image's [
This includes the amount of cracking J and the amount of smearing J exhibited by the printed image.Parameters of the printing system that directly influence the characteristics of the printed image are also identified and quantified. These parameters include the absorbency of the substrate, the temperature of the substrate, the distance between the printhead and the substrate, the temperature of the ink, the speed at which the ink flies toward the substrate, the volume of the ink droplets, and the , the diffusion coefficient of the ink is included.

By providing a system to control each of these parameters individually or in combination, printed images with optimal characteristics can be consistently and accurately reproduced without any problems as substrates change or the printing environment changes. Ru.

〔Example〕

FIG. 1 shows an inkjet device. The inkjet device uses a housing 12 containing a nozzle and a chamber containing an orifice I4. Housing 12 is surrounded by piezoelectric transducer 16 . converter 1
6 is energized or de-energized in response to the application of a drive voltage from power supply 18 provided between conductors 20 and 22.

An ink droplet 24 is ejected from the orifice 14 toward a target 26 (paper or other suitable substrate). Ink is supplied from reservoir 28 to the inkjet through communication tube 30.

The ink in the reservoir 28 is generally a changeable ink that is solid at low temperatures and undergoes a phase change to become liquid at elevated temperatures. Suitable inks are wax-containing inks that are solid or semi-solid at room temperature but become liquefied as the temperature rises, thereby making them exjectable from the orifice 14. However, the invention is not limited to wax-containing inks.

The heated ink solidifies when it comes into contact with the target 26 . The solidification rate of the ink is related to the degree of penetration into the target 26 and is one major factor in the degree of penetration.

Heating of the ink is accomplished by immersing the reservoir 28 in a bath of hot water 32 or by subjecting the reservoir 28 to other suitable heating means. The communication tube 30 and the inkjet itself are heated by an infrared lamp 34 or other suitable means.

FIG. 2 shows ink Il! directed from the orifice 14 to the target 26! The i24 is shown in flight. As shown in FIG. 3, when the ink droplet 24 comes into contact with the fibrous target 2G, the ink droplet 24D penetrates into the target 26 due to the capillary action of the target 26.

FIG. 4 shows an inkjet having a chamber 110 with an orifice 114 in the housing +12. The piezoelectric transducer 116 is energized or depressurized in response to a pulsed voltage v h < applied between the electrodes 120 , 122 to create an electric field across the transducer 116 .

The reservoir or manifold 130 with inlet 124 and chamber 110 are heated so that the ink remains in a liquid state. Without such heating, the ink reverts to a solid state. In other words, when the ink is heated, it undergoes a phase change and becomes liquid, making it ready to be ejected from the orifice 114. Manifold +30 may be replaced by a larger reservoir, not shown.

Heating of the ink in chamber +10 is effected by electrical heating means. In FIG. 4, the adding means is represented by a resistor 128 connected to the power supply.

Printed images produced by the inkjet systems described above or similar systems can be identified by a number of stylizable characteristics. One of these properties is the roundness of the dots created by inkjet. A means to measure the roundness of this dot was developed in 1983.
No. 2,485, filed on March 27, 2005 (registered as U.S. Pat. No. 4,361,843). Print quality is generally related to the roundness of the dots, and a roundness of 0.7 or better is believed to be optimal as measured by the method described in the Moeki patent.

Another characteristic important in achieving a good printed image is dot size or diameter. In general, better printed images can be produced with relatively small diameter dots.

Yet another characteristic important to the overall quality of the printed image is the penetration of the ink below the surface of the substrate and the agitation of the ink that remains on the surface of the substrate. This property is particularly important if the ink used is a hot melt ink beat phase change ink.

In standard inkjet printing techniques, liquid ink generally impinges on an absorbent substrate and penetrates the fibers of the substrate by capillary action or chemical absorption.

When it comes to hot melt ink, the printing technology is slightly different. This is because hot molten ink undergoes a phase change from liquid to solid after being ejected from the printhead. As a result, the degree of penetration of the hot melted ink into the substrate surface can be quantified and controlled. Similarly, the amount of ink remaining on the surface of the substrate can also be quantified and controlled. The degree to which the ink remains on the substrate surface is referred to as the tactility of the ink. We use this term because hot molten ink technology can create raised or Braille-like prints that can be detected by touching the surface of the substrate with your finger. It is.

Yet another characteristic that plays an important role in the overall quality of the printed image is its durability. Durability of the printed image is particularly important when most of the ink remains on the substrate surface after printing, which is exactly the case with hot melt ink technology. Having a significant amount of ink on the surface of the substrate means that there is a lot of ink that will crack or crease after printing is complete. The durability of a printed image can be quantified by both the degree of cracking and the degree of scuffing of the printed image. A method for quantifying and numerically expressing the durability of printed images in terms of cracking and rubbing is described below.

The method used to numerically express cracks is as follows. 1
A sheet of printed sample paper is used and a weighted roller device folds the sample paper along a stiff, smooth surface. This roller device is approximately 10 cm long and 3.2 cm in diameter, covered with 0.3 cm thick rubber, and has a Shore Adurometer hardness.
ss) is preferably 60 ra. The weight of the roller is preferably in the range of 22 kilograms to 4.4 kilograms and will vary depending on the sample paper.

Using this roller, fold the sample paper so that the side with the letters is on the inside. A firm crease is created by first placing the roller near the edge of the sample paper and then moving the roller slowly across the sample paper. Care must be taken not to apply excessive force to the sample paper.

Open the sample paper and place the sample paper so that the creases are visible. Then trace the crease above each letter and record the degree of cracking observed. The degree of cracking is evaluated as follows. That is, if no cracks are observed, the degree of cracking is evaluated as "0". If small cracks are observed, the degree of cracking is evaluated as rlJ.

If large cracks are observed, the degree of cracking is evaluated as r2J. Preferably - a minimum of 20 characters per fold of the book should be evaluated for cracking, and a minimum of two separate print sample papers should be used for each evaluation.

The percent cracking is then determined by dividing the number of characters that exhibited cracking by the total number of characters observed and multiplying by 100. The crack value may be determined by dividing the rating value by the total number of characters observed and summing for each rating. Such a method, quite contrary to other methods, allows the quantification and evaluation of the durability improvement of the printed image. This method quantifies the improvement in crack resistance caused by changes in the chemical composition of the ink, the temperature rise of the ink, the temperature rise of the paper, and the like.

The following materials are used to measure the degree of abrasion of printed images. That is, the Southerland rub tester (SouLherl)
and rub tester), a smooth, rigid paper support such as an aluminum sheet, and an Eberhard-F
aber Pink Pearl 101 erase
r) and double-sided adhesive tape. (The Southerland rub tester is a device officially used in the paper industry as a means of measuring print rub.) Pink Pearl 101 eraser was attached to a weight of approximately 0.9 kg using double-sided adhesive tape. Attach. A print sample paper is placed facing the eraser and the paper support is placed directly below the sample paper. Attach the above-mentioned paper to a rubbing tester and rub it back and forth 60 times, making sure that the sample paper does not slip during this period. Then remove the weight and use your fingers to remove any dirt that has accumulated on the surface of the eraser. This eraser can be used repeatedly until it wears out by about 25 percent.

The sample paper is then evaluated using an optical character tester (such as one manufactured by Moore Business Machines).

Using this character tester, the reflectance of the @ (ji) region located between the two lines of the rubbed character is measured. Calculate the average reflectance based on at least ten measurements.

The optical density is then calculated according to the following formula:

Optical density = log(1/reflectance) The rubbing bond is the ground between the two rubbed printed lines (
It is expressed numerically based on the optical density of the same region.

The analysis is based on the increase in optical power between two rubbed character lines. - The optical density of boat fishing paper is between 0.05 and 0.05. It is within the range of IOa degrees. Concentrations that increase within this range are used to evaluate the degree of abrasion.

Using the methods described above and others, it has been empirically determined that the properties of the printed image are influenced by various parameters associated with the phase change ink, the substrate to be printed, and the printing equipment. . Among those parameters are:

A) Temperature of the substrate B) Velocity of the ink (driving voltage) C) Absorption of the substrate D) Volume of the ink E) Temperature of the ink (viscosity) F) Distance from the substrate to the print head G) Diffusion coefficient of the ink H) Surface Wetting Properties The influence of each or a combination of these parameters on optimal print durability and quality is discussed below.

Temperature of the board It has been confirmed that the durability of printed images is affected by the temperature of the board. This is the next table! is shown. In this table, the degree of abrasion of printed characters is measured on paper printed at various paper temperatures.

Table 1 Durability (abrasion degree)/temperature paper)
Rub 11 degrees 1 list price 23 degrees Celsius
0,3038℃
0,2049℃
0, 07
The data shown in Table 1 are approximately constant 1ML at 90°C.
This was obtained using an ink with a viscosity of about IO centipoise. This measured value of the degree of abrasion was obtained using the above-mentioned method for evaluating the degree of abrasion. A decrease in print quality was observed as the paper temperature rose to about 49°C.

Table 2 shows the relationship between the durability of printed characters and the temperature of the substrate.

Table 2 Durability (degree of cracking)/Temperature (% of large cracks σ■) D
PC Thirty Hammer Mill
a+er(^ccept-(Cranes')(DpC
cer9 engineering tJ6 m1ll) ance)
tificate) 30℃ 6.09
Mil 34? 55'F 62
% 84?35 6.40 2
6 38 36 5840
6.77 18 29
38 7245 7.12 6
23 12 3850
7.24 0 27 1
552 The measurements shown in Table 2 were made using an ink maintained at a nearly constant temperature of about 106° C. and a nearly constant viscosity of about 10 centipoise. All crack values were determined by the crack evaluation method described above.

As shown in Table 2, the degree of major cracking at a given paper temperature varies depending on the type of paper used. The greatest amount of large cracks were observed on the DpC Certificate paper. The least amount of large cracks were observed in the hammer mill paper. It is believed that this difference in the amount of cracking is related to the difference in the porosity of the paper. That is, Hammermill paper was the most porous of the samples used, and DpC Certificate paper was the least porous.

Table 2 shows the existence of a relationship between substrate temperature and dot size. (Dot sizes listed are for hammermill paper.) Again, similar to Table 1, a decrease in print quality was observed when the substrate temperature exceeded about 50°C.

As shown in Table 2, the temperature of the paper is directly related to the platen itself and can be controlled by adjusting the temperature of the platen itself. During printing, the platen and substrate are typically in close physical proximity and, if not, in actual direct physical contact. Therefore, due to the transfer of heat between the platen and the paper, the temperature of the platen accurately indicates the temperature of the paper at the time and location of printing. For similar reasons, the temperature of the paper itself can be controlled by controlling the temperature of the platen. This control can be achieved, for example, by incorporating an electrical resistance element into the platen structure.
Alternatively, this can be accomplished by blowing a regular stream of thermally controlled air toward the platen (or directly toward the paper itself). Thermal sensing elements are disposed within or adjacent to the platen so that the temperature of the platen or substrate is measured and adjusted in response to the measurements using a feedback closed circuit. Those skilled in the art will appreciate that a variety of methods and mechanical devices can be used to control the temperature of the paper either directly or through the platen.

It has been confirmed that the tactility of printed images is affected by the temperature of the paper. Generally, as the temperature of the paper increases, the tendency of the ink to spread increases. Therefore, the tactility of the printed image decreases as the temperature of the paper increases.

In the printing system of the present invention, the paper temperature is approximately -40
℃ to about 200°C (ie, about 50°C higher than the melting point of the hot melt ink, which is 70 to 150°C). The temperature of this paper ranges from about 15℃ to about 4℃.
It is preferable to control the temperature within a range of 5°C.

Ink Velocity (Drive Voltage) It has been established that the properties of printing acids are influenced by the speed at which the liquid jet is deposited on the substrate. This is shown in Table 3.

Increased drive t1 voltage to 25 volts and 218' to 25 volts; Sho Table 3 Improved durability by heating the platen and controlling the size of the dots (big crack 1) Platen 1 degree Dot Oshima ＾ BC30
°C5,984 345 6B 67%40
°C 6.00mil 20% 3B
2H2O℃ 6.77mil 18% 2
9% 38%41? 48% 70S ＾ = Happan-Mill B. 1 xerbutance C. Crain's D = DpC call-tificate 73% 47τ 36 In the preferred embodiment of the present invention, the speed at which the ink impinges on the substrate is related to the drive voltage of the inkjet printing device. are doing. As the drive voltage increases, the speed at which the ink impinges on the substrate increases.

Table 3 thus provides data related to drive voltage rather than speed related data.

The first two rows of Table 3 show that changes in ink velocity and volume, and therefore drive voltage, allow approximately equal sized ink dots to be printed on substrates at various temperatures. There is. At 30°C, 5.98 mil size ink dots are printed using a 25 volt drive voltage. The temperature of the platen increases by 10℃ and the temperature rises to 4.
At 0° C., the temperature of the paper (substrate) increases so that hot melted ink spreads more easily on the paper. Therefore, to keep the dot size the same under this increased temperature, the drive voltage is reduced to 21 volts.

As further shown in Table 3, changes in drive +1 pressure (ink velocity and volume) and changes in substrate temperature also affect the percentage of large cracks observed in printed substrates. Generally, as the drive voltage decreases and the substrate temperature increases, an improvement (reduction) results in a percentage of large cracks having a value anywhere between approximately 35% and 70%. The degree of this change varies depending on the temperature of the filter paper used. The least improved paper is DpC Certificate paper, which has the least porosity.

The first and third rows of Table 3 show that using the same driving voltage, the temperature
The results are shown when printing on paper at 0°C and 30°C. As you can see, even with the same driving voltage of 25 volts, when the paper temperature is 40°C, the dot size is 6.77 mils (
That is, the value is almost I mil higher than if the paper temperature was 30°C. It has been experimentally determined that an increase in drive voltage of about 1 volt changes the dot size by about 0.2 mils or 2XI (I' inches).

Ink velocities employed in the present invention range from about 2 meters/second to about 60 meters/second, although preferred ink velocities are from about 5 meters/second to about 20 meters/second.

The absorbency of the substrate and the volume of the ink drop The properties of the printed image are also influenced by the absorbency of the substrate and the volume of the ink drop ejected from the printhead. This fact is shown in Table 4 below.

Table 4 Changes in durability Past data P.S.I. STD PS 1 MPII -O,S.

P EMPII +O,S.

Kano EMPI+ +0.8 Sho:STD =li drop-like character EMPI+・! In Table 1, the word "S T D" is used as a drifting (
5 standard) Add color to the characters. ” EM P I
The word (emphas 1zed)
) Letters, that is, the color of the wire print that does not necessarily have additional ink on the nape. The word "os" suggests an overstrike print, or double layer of ink.

The bottom of the first three vertical bars shows the percentage of major cracks observed after the first pass of the printhead. The tops of these three vertical bars indicate the percentage of large cracks observed after the second pass of the print head deposited a new layer of ink over the already printed 1' drop of ink. The lines within the vertical bars indicate the crack values with a low distribution width, and these vertical bars indicate the maximum and minimum values of the crack inspection data.

In some hot melt ink applications, after the first layer of ink has been deposited on the substrate, the print head returns to its original position and passes over the substrate again.
The new ink layer is deposited directly onto one portion of the first previously deposited ink layer, creating an identical printed image. As a result, in such applications, twice as much ink is applied to the substrate. During the second pass of the print head, the initial ink layer that was temporarily deposited has penetrated the substrate and returned to the body solid state.Therefore, there is almost no new ink layer on the substrate itself. Total heat does not penetrate.

Generally, newly deposited hot melted ink does not have sufficient heat capacity to melt the initial ink layer.

Therefore, the new ink layer overlays the surface of the first ink layer, and as a result, a decrease in the durability of the print is caused by this new ink layer.

The last two vertical bars at &=1 indicate the percentage of large cracks observed for papers where the porosity is very low and therefore ink penetration is very difficult. Therefore, a significant decrease in print durability is observed when the amount of ink deposited on the substrate increases or the absorbency of the substrate decreases.

The absorbency of a weir plate is influenced by a variety of factors, including substrate porosity, surface smoothness, fracture strength, internal dimensions, and external dimensions. However, it has been determined that the absorbency of a substrate is primarily related to the porosity of the substrate. This porosity can therefore be used as a guide to selecting a suitable absorbent substrate.

Standard chef yield unit (5 hel'rield)
The substrate used in the present invention exhibits a porosity of any value from about 20 to about 500 fyield units, as measured using , from about 20 ft. yield units to about 150 ft. yield units.

As used herein, the term "ink volume" refers to the volume of ink (eg, as shown in FIG. 2) ejected from the printhead toward the substrate as individual droplets. The volume of this ink droplet can be controlled by controlling the viscosity of the ink in combination with the driving voltage.

For example, at a constant viscosity, the body of the ink drop h1 increases with increasing driving voltage. Instead, at a constant drive voltage, a decrease in viscosity results in an increase in ink drop volume.

In the present invention, the volume of the ink drops ejected from the printhead varies from about 1 x 10-9 cm3 to about 500 x 10-9
cm3, with preferred ink drop volumes ranging from about 50 x I0-9 cm' to about 2° O x l0-I1c.
It is within the range of m'.

Ink Temperature (Viscosity) It is known that the characteristics of printed images are affected by the temperature of the ink attached to the substrate. This fact is shown in Table 5.

Ink temperature 90 °C 10 °C 120 °C 130 °C Table 5 Head temperature Ink viscosity! 0.0 6.5 5.5 4.5 Rub I constant value cP 0. 30 cP Q 26 cP O, 22 cP O, 19 As shown in Table 5, there is a negative correlation between the temperature of the ink and the viscosity of the ink. In general, the logarithm of viscosity (log
) is proportional to I/humidity temperature. Furthermore, as the temperature of the ink increases, the degree of rubbing generally decreases. The measurements listed in Table 5 were made on paper that was kept at room temperature (21° C.) during the printing process and on drive voltages that were held constant during the entire printing operation.

By varying the temperature of the printhead, and therefore the temperature of the ink, it is possible to increase the penetration power of the ink with little deterioration in print quality. Thus, by varying the temperature of the printhead and thus the temperature of the ink, the tactility or durability of a particular paper can be achieved to a particular value.

Table 6 further shows the effect of the combination of changes in drive pressure and head temperature on print durability using various porous papers.

Table 6 11. ! , size of 55 to 5.6 mil, large change in durability at head temperature of 1η no I (♂) Viscosity STD EMP II + 0 SI 2 cP Sanha +, I00℃, dot size 5.55 Mill, 1. Dp
c+-Tificate 1+, 7xeptance Bond C, Hammer; Le Silacopy (1, Tarain's Breast 2.100°C, dot size 5.61 mil 9.
0 cPa.
Table 6 shows that the penetrating power of the ink into the base is strengthened by using a hot ink, but the volume of the ink droplet is compared. This proves the advantage of keeping the drive voltage constant (that is, lowering the drive voltage). Ink drop size for the measurements listed in Table 6 was maintained in the range between 5.5 and 5.6 mils.

In the present invention, the ink temperature is within the range of about 10<0>C to about 200<0>C, with the preferred ink temperature being within the range of about 70<0>C to about 150<0>C. This corresponds to a jettable viscosity in the range of about 1 centipoise to about 50 centipoise, preferably in the range of about 5 centipoise to about 20 centipoise.

Distance from Inkjet Head to Substrate The characteristics of the printed image are also affected by the distance between the substrate and the print head. This fact is shown in Table 7.

Table 7 Female dot size
0.022 ino f 5 to not reach the paper
．． 5 mil 260.835
5.2
290.100 4.9 (i! MI minute 1
1) 510.220 4.
2 460500
3.9 663
．． 000
1 (10%) From the data in Table 7, it can be seen that the dot size decreases as the distance between the printhead and the printhead increases. If the ink drop tail completely separates from the ink drop body before reaching the substrate, the distance between the substrate and printhead is approximately 3
In the case of inches, the hot molten ink no longer reaches the substrate and therefore the print is not washed out at all.

Additionally, Table 7 shows that the degree of penetration of the hot molten ink into the substrate is also influenced by the distance between the substrate and the print. In general, the amount of hot melted ink that remains on the substrate surface without penetrating the dam can be increased by increasing the distance between the substrate and the ink-wet printhead. Therefore, the final tactility can be controlled by adjusting the distance between the printhead and the paper.

The printhead and substrate of the present invention are separated by a distance of any value from about 0.001 inch to about 1 inch, with a preferred separation distance of about 0.025 inch to about 0.02 inch.
It is within the range of 150 inches.

Diffusion Coefficient Furthermore, it has been determined that the properties of the printed image are influenced by the diffusion coefficient of the hot melted ink.

The diffusion coefficient of ink is defined by the following equation.

Diffusion Coefficient = Thermal Conductivity Specific Heat x Specific Gravity The magnitude of the diffusion coefficient determines how quickly an object at a non-uniform temperature approaches an equilibrium state. For hot melt inks of the present invention, this number is related to the rate at which heat is lost from the ink and the rate at which solidification occurs at the substrate. The rate of this loss and solidification is then related to both the degree of penetration into the substrate and the degree of spread over the substrate surface.

The hot melt ink of the present invention has a diffusion coefficient of approximately 0°002
2 cm''/sec to about 0.00056 cm'/sec. Preferred diffusion coefficients are:
Approximately 0. 0010 cm'/sec to approximately 0.0006 c
m'/sec.

It has been confirmed that the properties of purine (purine) are influenced by the surface wetting properties (1).The surface wetting properties are influenced by changes in the surface tension of the ink or by changes in the temperature of the ink. It is influenced by the control of the "critical" surface tension of the substrate.

The present invention is particularly valuable when printing is performed on different substrates and under different environmental conditions. For example, the printing system of the present invention can be employed in a portable barcode printer. Such printers can be moved and placed near a conveyor belt to print barcode labels on each of a large number of boxes or other packaging materials as they pass by. The size, shape, structure, and other physical attributes of such packaging materials frequently change. Further, the working environment (temperature, humidity, etc.) of the barcode printer is not exactly the same for each conveyor held. Therefore, it is highly desirable to be able to print code labels with uniform quality and durability by providing a barcode printer that is adaptable to changes in substrate materials and work environments. Use of the present invention controls the combination of multiple parameters of barcode printing. This allows for optimal print durability of barcode labels regardless of changes in substrate material or printing environment.

In one embodiment of the invention, the prinching stem is I
Or includes multiple adjustment dials, with this dial! Alternatively, multiple of the above parameters (including ink temperature, substrate temperature, drive voltage, and distance from the substrate to the inkjet printhead) can be controlled.

This dial allows the user of the printing system to continuously change one of the properties of the print (e.g. ink permeability, from complete penetration to complete impermeability (maximum tactility)). change).

In another embodiment of the present invention, a code printer (barcode printer) is provided that is capable of decoding and printing high quality and durable printed images on a large number of labels or other substrates.

This printer prints a barcode and then automatically reads the barcode. If the readings indicate that the printed image is not of optimal quality, then automatic adjustment of the print head temperature, paper temperature, drive voltage, and print head distance is performed. The readings are performed until the results are acceptable.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the ink jet device, Figure 2 is an enlarged partial diagram of an ink droplet flying from an orifice towards a target, and Figure 3 is a partial enlarged diagram of an ink droplet flying towards a target and penetrating the target. 4 are partial schematic sectional views of another ink jet device. 12, +12... Housing, 14.114... Orifice, 16, +16... Piezoelectric transducer, I8...
Power supply, 20.22,... conductor, 24... ink drop,
26...Target, 28...Storage vessel, 30...Communication pipe, 32...Hot water tank, 34...Infrared lamp, 110...
Chamber, 120.122... Electrode, +24... Inlet,
+28...Resistor, +30...Manifold Applicant Data Products Corporation Figure 3 Figure 4 US, Lightning source procedure? rlT square (method) % formula % Name of the invention Relationship with the case of the person who corrects the method and device for improving print characteristics Patent applicant Data Products Corporation

Claims (1)

[Claims] (1) Provide a substrate with a predetermined absorbency, provide an ink with a predetermined diffusion coefficient, adjust the temperature of the ink to 10°C or more and 200°C or less, and set the temperature of the substrate to - adjusting the temperature between 40° C. and 200° C., adjusting a distance between the print head and the substrate, and ejecting a predetermined volume of ink from the print head toward the substrate at a predetermined speed. A method of forming generally circular ink dots having a predetermined diameter, tactility and durability when hot molten ink ejected from an inkjet device adheres to a substrate. (2) Select a substrate with an absorbency within the range of 0 Sheffield units to 500 Sheffield units, heat the substrate to a temperature within a predetermined range, and heat the substrate to a temperature within a predetermined range of 0.002
Selecting an ink with a diffusion coefficient within the range of 2 cm^2/sec to 0.00056 cm^2/sec,
heating the inkjet ejection drive means to a predetermined diameter when the hot molten ink ejected from the inkjet device adheres to the substrate; A method of forming approximately circular dots of ink with a diameter of . 2. The method of claim 1, further comprising the step of: (3) increasing the spread of the dots on the substrate by controlling the trailing length of the ink ejected from the inkjet device. (4) Select a substrate with an absorbency ranging from 0 Sheffield units to 500 Sheffield units, and from 0.0022 cm^2/sec to 0.00056 cm^2
Selecting an ink with a diffusion coefficient within a range of up to /second, adjusting the temperature of the ink to 10°C or more and 200°C or less, adjusting the temperature of the substrate to -40°C or more and 200°C or less, and Adjust the distance between the print head between 0.001 inch and 1.0 inch, 1 x 10^-^9c
ejecting said ink in the form of droplets with a volume between m^3 and 500 x 10^-^9 cm^3 from said print head towards said substrate at a speed between 2 m/s and 60 m/s. A method of ejecting hot, molten ink from a printhead onto a substrate, including the steps of: (5) Select a substrate with a predetermined absorbency, select an ink with a predetermined diffusion coefficient, control the temperature of the ink at 10°C or more and 200°C or less, and keep the temperature of the substrate at -40°C or more and 200°C or less. ℃ or below, adjusting a distance between a print head and the substrate to a predetermined distance, and ejecting a predetermined volume of ink from the print head toward the substrate at a predetermined speed. A method of attaching hot melted ink to a substrate. (6) The prescribed absorbency is 0 Sheffield units and 500
6. The method of claim 5 between Sheffield units. (7) The prescribed absorbency is 20 Sheffield units and 15
6. The method of claim 5, wherein the amount is between 0 Sheffield units. (8) The method of claim 5, wherein the predetermined diffusion coefficient is between 0.0022 cm^2/sec and 0.00056 cm^2/sec. (9) The method of claim 5, wherein the predetermined diffusion coefficient is between 0.0010 cm^2/sec and 0.0006 cm^2/sec. (10) The method according to claim 5, wherein the temperature of the ink is between 70°C and 150°C. (11) The method according to claim 5, wherein the temperature of the substrate is between 15°C and 45°C. 12. The method of claim 5, wherein the predetermined distance is between 0.001 inch and 1 inch. 13. The method of claim 5, wherein the predetermined distance is between 0.025 inches and 0.150 inches. (14) The given volume is 1 x 10^-^9cm^3 and 50
The method according to claim 5, wherein the diameter is between 0x10^-^9cm^3. (15) The given volume is 50 x 10^-^9cm^3 and 2
The method according to claim 5, wherein the area is between 00x10^-^9cm^3. (16) The predetermined speeds are 2 m/s and 60 m/s.
6. The method of claim 5, wherein the method is between seconds. (17) The predetermined speeds are 5 meters/second and 20 meters/second.
6. The method of claim 5, wherein the method is between seconds. (18) a first selection means for selecting a substrate having an absorption between 0 Sheffield units and 500 Sheffield units; ．． 00056cm^2
second selection means for selecting an ink having a diffusion coefficient between /sec; first control means for controlling the temperature of the ink within a range of 10°C to 200°C; and controlling the temperature of the substrate to - a second control means for controlling the temperature within a range of 40°C to 200°C; and a distance between the substrate and the print head of 0.001.
Adjustment means to adjust between inch and 1.0 inch, 1 x 10^-^9 cm^3 and 500 x 10^-^9 cm
ejection means for ejecting said ink in the form of droplets with a volume between ^3 from said print head towards said substrate at a speed between 2 m/s and 60 m/s. A device that injects water from a print head toward a substrate.