JP2009262343A - Ink ribbon cassette - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink ribbon cassette which can continuously print with a high density close to an initial set value and with a good quality of printing from an early stage of printing to an estimated life, can rapidly decrease the density of the printing after reaching the estimated life to let a user know a replacement timing, and can prevent the quality of the printing from being deteriorated and an ink ribbon from being broken. <P>SOLUTION: The ink ribbon cassette 1 has ink rollers 17 and 18 consisting of porous bodies storing ink fed to the ink ribbon 3 and its switching mechanism, and is composed in a relation of equation (1): ρ<SB>1</SB>>ρ<SB>2</SB>wherein the apparent density of a porous body forming the ink roller 17 selected at the initial stage is ρ<SB>1</SB>, and the apparent density of a porous body forming the ink roller 18 selected by switching is ρ<SB>2</SB>, or in a relation of equation (2): μ<SB>1</SB>>μ<SB>2</SB>wherein the viscosity of the ink impregnated in the ink roller 17 is μ<SB>1</SB>and the viscosity of the ink impregnated in the ink roller 18 is μ<SB>2</SB>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink ribbon cassette having an endless ink ribbon used for a dot impact printer or the like.

  By selectively striking a plurality of pins corresponding to dots arranged vertically and horizontally on the ink ribbon stacked on the paper surface in correspondence with the character data, the ink impregnated in the ink ribbon is transferred to the paper surface for printing. Dot impact printers to perform are known. Since the dot impact printer is almost the only printer that can print on a plurality of sheets of paper at the same time by stacking a plurality of sheets with copy paper (non-carbon paper, etc.) in between, various printing such as slip printing It is still widely used in the field.

  Ink ribbons used in dot impact printers are traditionally made endless by connecting both ends of a fabric ribbon made of synthetic fibers, etc., but the ink is impregnated in the gap between the fibers and can be attached to and detached from the dot impact printer. Those incorporated in the ink ribbon cassette to be mounted are used.

  The ink ribbon cassette is configured to send the endless ink ribbon, a printing unit that performs printing using the ink ribbon, a storage chamber that stores the ink ribbon, and an ink ribbon that is stored in the storage chamber to the printing unit. And a passage for re-accommodating the ink ribbon after printing in the printing portion, and an ink replenishing portion provided in the middle of the passage for replenishing ink to the ink ribbon.

  As the ink replenishing section, the ink ribbon impregnated with ink impregnated with a porous body such as sponge, felt, fiber bundle, non-woven fabric, etc. is supplied to the ink ribbon via a replenishing roller that rotates with the ink ribbon feeding, for example. The thing to replenish is mentioned. According to the ink ribbon cassette, the endless ink ribbon can be repeatedly circulated through the passage while being replenished with ink in the ink replenishing portion provided in the middle of the passage, and can be printed by being circulated to the printing portion.

  A dot impact printer is required to continue good printing having a sufficient density for as long as possible without impairing printing quality. However, in the conventional endless ink ribbon, both ends of the ink ribbon are joined by welding or the like, and the gap between the fibers is often crushed at the joined portion.

  For this reason, the joint portion cannot be sufficiently impregnated with the ink replenished by the ink replenishing portion, and excess ink tends to accumulate on the surface of the ink ribbon, in particular, at the stepped portion due to the joined end portion. Further, there is a problem that the quality of the printing deteriorates due to the ink smeared or the paper soiled by the accumulated ink.

  Therefore, in order to solve such a problem, a so-called seamless type endless ink ribbon has been developed in which synthetic fibers and the like are knitted into a cylindrical shape in advance and then slit into the width of the ink ribbon to impregnate the ink. According to the seamless type ink ribbon, since the joint portion can be eliminated, it is possible to solve the problem that the printing at the joint portion is blurred and always perform good printing.

  The seamless type endless ink ribbon had a short circumference of about 1.5 to 3 m at the beginning of development. However, in recent years, it has become possible to manufacture a long one having a circumference of about 10 m. It has become. In the ink ribbon cassette using the long ink ribbon, it is necessary to increase the total amount of ink that can be replenished compared to the short one, and it is required to increase the amount of ink that can be accommodated in the ink replenishing body.

  However, there is a problem in that almost all of the ink stored in the ink supply body cannot be used up simply by increasing the ink supply body and increasing the amount of ink that can be stored.

  This is because the ink used in the dot impact printer has a high viscosity and low fluidity, and the larger the ink supply body, the more the ink supply body remains in the ink supply body, This is because the amount of ink not supplied to the ink ribbon increases.

Therefore, instead of increasing the size of the ink replenishing body, the number of the ink replenishing bodies is increased to increase the amount of ink that can be accommodated as a whole, and when almost all the ink in one ink replenishing body is used up, the next new There has been proposed an ink ribbon cassette provided with a switching mechanism that switches to an ink supply body and continues to supply ink (Patent Document 1).
Japanese Utility Model Publication No. 2-104263

  FIG. 2 is a graph showing an example of the relationship between the number of prints and the print density when printing is repeated using an ink ribbon cassette. Referring to FIG. 2, the ideal relationship between the number of prints and the print density is as shown by the solid line in the figure. In other words, the printing maintains the density as close as possible to the initial set value from the start of printing until the estimated life of the ink ribbon cassette, and the density decreases rapidly before and after reaching the estimated life. It is desirable to be able to inform the replacement timing of the ink ribbon cassette.

  However, even if printing is repeated using the type of ink ribbon cassette of the type described above that can switch the ink supply body during printing, the number of prints and the density of printing are changed according to the ideal relationship. However, there is a problem that the density of printing greatly fluctuates as shown by a two-dot chain line in FIG. 2, and the quality of printing fluctuates unstablely.

  For example, the ink ribbon cassette is provided in a state where a sufficient amount of ink is impregnated not only in the ink supply body but also in the ink ribbon in order to perform good printing whose density is an initial set value from the first printing. It is common. Therefore, when the ink ribbon is further replenished with ink from the first ink replenishment body at the initial stage of printing, the so-called over-replenishment in which the density of the print rises excessively beyond the initial set value. May occur (peak on the left side of FIG. 2).

  In addition, in an over-supplemented state, excess ink that could not be impregnated in the gaps between the fibers collected on the surface of the ink ribbon, and the accumulated ink may cause the print to smear or the paper to become dirty, degrading the print quality. is there.

  Moreover, after the printing is continued and the ink previously impregnated in the ink ribbon is consumed, the density of the printing suddenly and drastically decreases (the state immediately after the peak in FIG. 2), and then the ink supply body is switched. However, although the print density is not less than the usable limit value, it moves at a low level.

  This is because, in the conventional ink ribbon cassette, in order to suppress the increase in the print density in the over-replenished state as much as possible and to prevent the print quality from deteriorating, the ink from the ink supply body to the ink ribbon can be reduced. This is because the replenishment amount (the amount of ink replenished per unit printing number) is set to be low in both ink replenishing bodies before and after the switching.

  Further, as described above, since only a small amount of ink is consumed from the ink replenishing body set with a low ink replenishing amount as described above, even if the ink replenishing body after switching exceeds the preset life expectancy of the ink ribbon cassette. There is a case in which a certain amount of ink or more is continuously replenished and the print density is maintained at a usable limit value or more even when the estimated life is exceeded.

  In that case, the ink ribbon cassette that has exceeded its expected life can be used forever, and the ink ribbon fabric that is repeatedly struck by the pin every time printing is performed may loosen or open holes, resulting in deterioration in print quality. In addition, if the printing is still continued, the ink ribbon may be damaged.

  In order to reduce the density of printing below the usable limit value in the vicinity of the assumed life, it is conceivable to adjust the amount of ink stored in the ink supply body to be used after switching, in particular, to be small.

  However, as described above, since only a small amount of ink is consumed from the ink supply body in which the ink supply amount is set to be low, the print density at the end of the ink amount is as shown by a broken line in the figure. It will decline slowly. Therefore, there is a problem that it is difficult to determine whether or not the print density has reached the usable limit value.

  The object of the present invention is to continue printing with a high density close to the initial set value and good print quality from the initial printing to the assumed life without greatly disturbing the printing density, and with the expected life. After reaching the above, it is an object to provide an ink ribbon cassette capable of informing the user of the replacement time by rapidly decreasing the density of the print and preventing the deterioration of the print quality and the breakage of the ink ribbon.

The present invention is an ink ribbon cassette that performs printing by circulating an endless ink ribbon, and includes an ink supply unit that supplies ink to the ink ribbon, and the ink supply unit includes a plurality of inks that store ink to be supplied. An ink supply body and a switching mechanism for switching an ink supply body for supplying ink to the ink ribbon. Each ink supply body is made of a porous body that can be impregnated with ink, and each ink supply body The following (a) and (b):
(a) The apparent density ρ ₁ (g / cm ³ ) of the porous body forming the ink supply body selected in the initial stage from the start of use of the ink ribbon cassette to the switching by the switching mechanism, and the switching by the switching mechanism The apparent density ρ ₂ (g / cm ³ ) of the porous body forming the ink supply body selected by the formula (1):
ρ ₁ > ρ ₂ (1)
In a relationship,
(b) The viscosity μ ₁ (Pa · s) of the ink impregnated in the ink supply body selected in the initial stage and the viscosity μ _{2 of the} ink impregnated in the ink supply body selected by switching by the switching mechanism. (Pa · s) is the formula (2):
μ ₁ > μ ₂ (2)
In a relationship,
The ink ribbon cassette satisfies at least one of the conditions.

According to the ink ribbon cassette of the present invention, the apparent density ρ ₁ (g / cm ³ ) of the porous body forming the ink supply body selected in the initial stage is increased, or the ink supply body is impregnated. By increasing the viscosity μ ₁ (Pa · s) of the ink, it is possible to suppress the amount of ink per unit printing of the ink that exudes from the ink supply body.

  For this reason, the ink replenishment amount per unit print number in the initial stage is suppressed as much as possible to prevent an increase in print density due to oversupply, and in the initial stage, the print density is close to the initial set value. In addition to being able to maintain, it is possible to prevent bleeding and the like caused by the oversupply, and to maintain good print quality.

Further, the apparent density ρ ₂ (g / cm ³ ) of the porous body forming the ink supply body selected by switching by the switching mechanism is made smaller than the apparent density ρ ₁ or impregnated in the ink supply body. By increasing the viscosity μ ₂ (Pa · s) of the ink to be smaller than the previous viscosity ρ ₂ , the amount of ink permeated per unit printing of the ink to ooze out from the ink supply body is increased from the initial stage. Can be made.

  As a result, the ink replenishment amount per unit print number after the switching is increased, and the ink ribbon is replenished with more ink than in the initial stage, so that a decrease in print density can be suppressed.

  In addition, by replenishing a large amount of ink as described above, almost the entire amount of ink stored in the ink replenishing body can be used up quickly before and after the preset expected life of the ink ribbon cassette.

  For this reason, the print density can be rapidly lowered below the usable limit value near the estimated life, and the user can be notified of the replacement timing of the ink ribbon cassette. It can also be prevented.

In the ink ribbon cassette having the switching mechanism, the ink replenishment amount W ₁ (g) per unit print number in the initial stage and the ink replenishment amount W ₂ (g) per unit print number after switching. The ratio W ₂ / W ₁ is the formula (3):
1.2 ≦ W ₂ / W ₁ ≦ 3.0 (3)
It is preferable that

When the ratio W ₂ / W ₁ is less than 1.2 and both the replenishment amounts W ₁ and W ₂ are both large, there is a possibility that over supplementation may occur. In addition, if both the replenishment amounts W ₁ and W ₂ are reduced in order to suppress the occurrence of excessive replenishment, after switching, it is not effective to replenish the ink from the initial stage and suppress the decrease in print density. There is also a risk of becoming sufficient.

  Therefore, in any of the above cases, there is a possibility that the effect of continuing printing at a high density close to the initial set value and good print quality from the initial printing to the assumed life may not be obtained. In the latter case, particularly, the amount of ink consumed from the ink replenisher used after switching is reduced, so at the end of the ink amount, the print density is rapidly reduced to inform the user of the replacement time. There is a possibility that the effect cannot be obtained.

On the other hand, when the ratio W ₂ / W ₁ exceeds 3.0 and the replenishment amount W ₁ is small, the replenishment amount W ₁ cannot catch up with the ink consumption, so the print density until switching is greatly increased. May decrease. Further, if it is attempted to maintain the density, it is necessary to switch quickly, and as a result, the print life may be significantly shorter than the assumed life. Further, when the ratio W ₂ / W ₁ exceeds 3.0 and the replenishment amount W ₂ is large, excessive ink is replenished after switching, resulting in a shortage of ink, resulting in an expected life of printing. There is a risk that it will be much shorter.

  Therefore, in any of the above cases, there is a possibility that the effect of continuing printing at a high density close to the initial set value and good print quality from the initial printing to the assumed life may not be obtained. Further, in the latter case, excess ink that could not be impregnated in the gaps of the fibers collected on the surface of the ink ribbon, and the accumulated ink may cause the printing to blur or the paper to become dirty, thereby deteriorating the printing quality. There is also.

In the present invention, while supplying ink to the ink ribbon from the ink supply body, in the draft printing (12 dots × 23 dots) using a dot impact printer of 24 pins (12 pins × 2 rows) and 180 dpi, Mincho The amount of ink consumed from the ink replenishment body, that is, replenished to the ink ribbon, when 26 characters from half-size uppercase letters A to Z of the body were sequentially printed until the total number of prints reached 3 million characters Let (g) be defined as the ink replenishment amounts W ₁ and W ₂ per unit print number.

  The ink ribbon cassette according to the present invention has a switching mechanism in which the ink replenishing section selects one of a plurality of ink replenishing bodies and switches the ink ribbon to replenish ink, and each ink replenishing unit. It is preferable that the body is made of a porous body that can be impregnated with ink because the structure and switching operation are simple and the switching effect can be obtained with certainty.

  According to the present invention, it is possible to continue printing with a high density close to the initial set value and good print quality from the initial printing to the assumed life without greatly disturbing the printing density, and with an assumed life. After reaching the above, it is possible to provide the ink ribbon cassette capable of informing the user of the replacement time by rapidly decreasing the print density and preventing the deterioration of the print quality and the breakage of the ink ribbon.

  FIG. 1 is a cross-sectional view showing an example of an embodiment of an ink ribbon cassette of the present invention. Referring to FIG. 1, an ink ribbon cassette 1 of this example includes a housing 2 integrally formed of plastic or the like, an endless ink ribbon 3 accommodated in the housing 2, and the ink ribbon 3. And an ink supply unit 4 for supplying ink.

  The housing 2 includes a pair of projecting portions 5 and 6 projecting from the vicinity of both ends of the upper side in the figure. A housing chamber 7 for storing the ink ribbon 3 in a zigzag manner and a replenishing chamber 8 for housing the ink replenishing portion 4 are provided in a region below the upper side of the housing 2 in the drawing. Further, passages 9 and 10 of the ink ribbon 3 for returning the ink ribbon 3 delivered from the storage chamber 7 to the storage chamber 7 through the supply chamber 8 are provided in the protrusions 5 and 6.

  Openings 11 and 12 are formed at the tips of the protrusions 5 and 6, and the ink ribbon 3 fed from the storage chamber 7 and supplied through the passage 9 is once exposed to the outside through the opening 11. After that, by taking the ink ribbon cassette 1 into the passage 10 through the opening 12, the printing unit 13 is configured to use the exposed ink ribbon 3 for printing when the ink ribbon cassette 1 is mounted on a dot impact printer (not shown).

  When the ink ribbon cassette 1 is mounted on a dot impact printer, the dot impact head having a plurality of pins of the dot impact printer is surrounded by the upper side of the casing 2 and the protrusions 5 and 6 of the ink ribbon cassette 1. 14, the ink ribbon 3 exposed by the printing unit 13 is interposed between a plurality of pins of the dot impact head and a sheet disposed opposite to the pins, and is used for printing. .

  The ink supply unit 4 includes a pair of feed rollers 15 and 16 and two ink rollers 17 and 18 as ink supply members for supplying ink to be impregnated into the ink ribbon 3. The feed rollers 15 and 16 function as feed members for the ink ribbon 3 by rotating in opposite directions with the ink ribbon 3 interposed therebetween.

  That is, in the drawing, the upper feed roller 15 is connected to the drive shaft of the dot impact printer when the ink ribbon cassette 1 is mounted on a dot impact printer (not shown), and a solid arrow in the drawing corresponds to the printing operation. Is driven to rotate in the direction indicated by.

  As the feed roller 15 rotates, the lower feed roller 16 is driven to rotate in the reverse direction as indicated by the solid line arrow, and the ink ribbon 3 sandwiched between the feed rollers 15 and 16 is moved accordingly. As indicated by a two-dot chain line arrow, the air is circulated from the storage chamber 7 to the storage chamber 7 through the passage 9, the printing unit 13, the passage 10, and the supply chamber 8.

  Each of the ink rollers 17 and 18 is made of a porous material such as sponge, felt, fiber bundle, or nonwoven fabric, and is impregnated with ink. Both ink rollers 17 and 18 are rotatably attached to a support member 19 via support shafts 20 and 21. One end of the support shaft 21 is inserted into a long hole 22 provided in the housing 2, and the support shaft 21 is slid along the length direction of the long hole 22.

  The support member 19 slides in the direction indicated by the white arrow in the drawing along with the slide, and slides in the direction opposite to the displacement position where the ink roller 18 is brought into contact with the feed roller 16 (not shown). As shown in the figure, the ink roller 17 can be displaced between a displacement position where the ink roller 17 is brought into contact with the feed roller 16.

  The support member 19 is fixed to the housing 2 by the screw 23 at any one of the displacement positions. The support member 19, the support shafts 20 and 21, the long hole 22, and the screw 23 constitute a switching mechanism 24 that switches an ink roller that supplies ink to the ink ribbon.

  At the displacement position shown in the drawing, when the ink ribbon 3 is fed by rotating the feed rollers 15 and 16, the ink roller 17 brought into contact with the feed roller 16 is indicated by a solid arrow as the feed roller 16 rotates. The ink ribbon 3 is replenished with the impregnated ink via the feed roller 16 while being driven and rotated in the reverse direction.

  In order to switch the ink roller for supplying ink to the ink ribbon, the screw 23 of the switching mechanism 24 is loosened, and the support member 19 is slid in the direction indicated by the white arrow in the drawing. Then, the ink roller 17 is separated from the feed roller 16, and the screw 23 is tightened in a state where the ink roller 18 is in contact with the feed roller 16 to fix the support member 19 to the housing 2.

  Thereafter, when the ink roller 18 rotates the feed rollers 15 and 16 to feed the ink ribbon 3, the ink roller 18 is impregnated while being driven to rotate in the reverse direction as indicated by the solid line arrow as the feed roller 16 rotates. Ink is supplied to the ink ribbon 3 through the feed roller 16.

When the ink roller 17 is an ink replenishment body selected in the initial stage from the start of use of the ink ribbon cassette 1 to the switching by the switching mechanism 24, and the ink roller 18 is an ink replenishment body selected by switching, the two ink rollers 17 , 18 are the following (a) and (b):
(a) The apparent density ρ ₁ (g / cm ³ ) of the porous body forming the ink roller 17 selected in the initial stage and the apparent density ρ of the porous body forming the ink roller 18 selected by switching ₂ (g / cm ³ ) is the formula (1):
ρ ₁ > ρ ₂ (1)
In a relationship,
(b) the viscosity of the ink impregnated into the ink roller 17 to be selected in the initial stages mu ₁ and (Pa · s), the viscosity μ ₂ (Pa · s of ink impregnated in the ink roller 18 which is selected by the switching ) And formula (2):
μ ₁ > μ ₂ (2)
In a relationship,
Must satisfy at least one of the conditions.

  Thereby, as described above, according to the ink ribbon cassette 1 of this example, the density of printing is high and close to the initial set value from the initial printing to the assumed life without greatly disturbing the printing density. Can continue to print with high print quality. Further, after reaching the assumed life, the printing density is rapidly reduced to notify the user of the replacement time, thereby preventing the deterioration of the printing quality and the breakage of the ink ribbon 3 in advance.

In addition, both the ink rollers 17 and 18 have an ink replenishment amount W ₁ (g) per unit printing number by the ink roller 17 selected in the initial stage and a unit printing number by the ink roller 18 selected after switching. The ratio W ₂ / W ₁ to the ink replenishment amount W ₂ (g) per the equation (3):
1.2 ≦ W ₂ / W ₁ ≦ 3.0 (3)
It is preferable that

When the ratio W ₂ / W ₁ is less than 1.2 and both the replenishment amounts W ₁ and W ₂ are both large, there is a possibility that over supplementation may occur. Further, when both the supply amounts W ₁ and W ₂ are reduced in order to suppress the occurrence of oversupply, the ink ribbon 3 is supplied with more ink than the initial stage from the ink roller 18 after switching, There is also a possibility that the effect of suppressing the decrease in printing density is insufficient.

  Therefore, in any of the above cases, there is a possibility that the effect of continuing printing at a high density close to the initial set value and good print quality from the initial printing to the assumed life may not be obtained. In the latter case, since the amount of ink consumed from the ink roller 18 is reduced, there is a risk that the effect of notifying the user of the replacement time by rapidly decreasing the print density at the end of the ink amount may be obtained. There is also.

On the other hand, when the ratio W ₂ / W ₁ exceeds 3.0 and the replenishment amount W ₁ is small, the replenishment amount W ₁ cannot catch up with the ink consumption, so the print density until switching is greatly increased. May decrease. Further, if it is attempted to maintain the density, it is necessary to switch quickly, and as a result, the print life may be significantly shorter than the assumed life. In addition, when the ratio W ₂ / W ₁ exceeds 3.0 and the replenishment amount W ₂ is large, excess ink is replenished from the ink roller 18 after switching, resulting in insufficient ink, resulting in printing. There is a risk that the life of the battery will be significantly shorter than the expected life.

  Therefore, in any of the above cases, there is a possibility that the effect of continuing printing at a high density close to the initial set value and good print quality from the initial printing to the assumed life may not be obtained. Further, in the latter case, excess ink that could not be impregnated in the gaps of the fibers collected on the surface of the ink ribbon, and the accumulated ink may cause the printing to blur or the paper to become dirty, thereby deteriorating the printing quality. There is also.

Note that the ratio W ₂ / W ₁ of the ink replenishment amount per unit print number is 1.2 or more and 2.8 or less, particularly 1. It is preferably 3 or more and 2.5 or less.

Specific ranges of the apparent density ρ ₁ and ρ _{2 of the} porous body, the ink viscosity μ ₁ and μ ₂ , and the ink replenishment amounts W ₁ and W ₂ per unit printing number are not particularly limited. The apparent density ρ ₁ and ρ ₂ of the porous body forming the ink rollers 17 and 18 combined with the ink ribbon 3 having a length of about ˜13 mm and a length of about 5 to 12 m satisfy the above formula (1), and the apparent density ρ ₁ is 0.23 to 0.40 g / cm ³ , particularly 0.25 to 0.38 g / cm ³ , and the apparent density ρ ₂ is 0.20 to 0.37 g / cm ³ , especially 0.22 to 0.35 g / Preferably it is cm ³ .

The viscosity μ ₁ and μ ₂ of the ink impregnated in the ink rollers 17 and 18 satisfy the above formula (2), the viscosity μ ₁ is 0.4 to 8.0 Pa · s, and μ ₂ is the viscosity 0.2. It is preferable that it is ˜5.0 Pa · s. The viscosity is expressed by a value measured using a B-type viscometer at a rotation speed of 60 rpm and a measurement temperature of 20 ± 2 ° C.

Further, the ink replenishment amounts W ₁ and W ₂ per unit print number satisfy the above-mentioned formula (3), and the replenishment amount W ₁ is 0.5 to 3.5 g, and the replenishment amount W ₂ is 1.0 to 4. 0.0 is preferred.

  According to the example shown in the figure, in the initial stage, the support member 19 is fixed to the housing 2 in a state where the ink roller 17 is in contact with the feed roller 16, and the ink ribbon 3 is impregnated with a necessary amount of ink. The ink ribbon cassette 1 is mounted on a dot impact printer for printing.

  Then, as the feed roller 15 connected to the drive shaft of the dot impact printer is driven to rotate, the ink ribbon 3 sandwiched between the feed rollers 15 and 16 is accommodated in the storage chamber 7 as indicated by the two-dot chain line arrow. The ink ribbon 3 is continuously circulated to the storage chamber 7 through the passage 9, the printing unit 13, the passage 10, and the replenishing chamber 8, and the ink ribbon 17 is continuously replenished with ink through the feed roller 16 while being replenished. Can print.

At this time, if the replenishment amount W ₁ (g) per unit printing of the ink replenished from the ink roller 17 is suppressed as much as possible, an increase in the print density due to oversupply can be suppressed. Therefore, in the initial stage, the print density can be maintained at a density close to the initial set value, and the blurring caused by the oversupply can be prevented, and the print quality can be kept good.

  When printing reaches a predetermined value, printing is stopped, the screw 23 of the switching mechanism 24 is loosened, the support member 19 is slid in the direction indicated by the white arrow in the figure, and the ink roller 17 is fed to the feed roller. The support member 19 is fixed to the casing 2 by tightening the screw 23 in a state where the ink roller 18 is in contact with the feed roller 16 while being separated from the support roller 19.

  When printing is resumed in this state, the ink ribbon 3 sandwiched between the feed rollers 15 and 16 is indicated by a two-dot chain line arrow in accordance with the rotational drive of the feed roller 15 connected to the drive shaft of the dot impact printer. As shown, the ink is circulated from the storage chamber 7 to the storage chamber 7 through the passage 9, the printing unit 13, the passage 10, and the supply chamber 8, and the ink ribbon 3 is supplied with ink from the ink roller 18 through the feed roller 16. However, continuous printing can be performed again.

At this time, the replenishment amount W ₂ (g) per unit printing of the ink replenished from the ink roller 18 is larger than the initial replenishment amount W ₁ (g), preferably 1.2 times or more. By setting the range to less than 0.0 times and supplying more ink to the ink ribbon than in the initial stage, it is possible to suppress a decrease in printing density.

  In addition, by replenishing a large amount of ink as described above, almost the entire amount of ink stored in the ink replenishing body can be used up quickly before and after the preset expected life of the ink ribbon cassette.

  For this reason, the print density can be rapidly lowered below the usable limit value near the estimated life, and the user can be notified of the replacement timing of the ink ribbon cassette. It can also be prevented.

  In addition, the structure of the ink ribbon cassette of this invention is not limited to the example of a figure. For example, the ink supply body is not limited to the ink roller, and may be an ink occlusion body fixed to the housing. There may be three or more ink replenishers.

  The switching mechanism selects any one of the plurality of ink supply bodies to supply ink to the ink ribbon, and when the predetermined number of prints is reached, in addition to the ink supply bodies, other ink supply bodies Alternatively, switching may be performed so that ink is replenished at the same time.

  In this case, the total amount of ink replenished from the plurality of ink replenishers after switching is too large, and printing with a sufficient density may occur even if the preset life of the ink ribbon cassette is exceeded. In this case, the ink ribbon cassette that has exceeded the expected life can be used forever, and the print quality may deteriorate or the ink ribbon may be damaged.

However, assuming that the total amount of replenishment amount per unit printing of the ink replenished from the plurality of ink replenishers after switching is W ₂ (g), the W ₂ is expressed with respect to the replenishment amount W ₁ (g). If the setting is made so as to satisfy (3), the above problem can be prevented.

(Preparation of ink)
Carbon black as a black pigment and, if necessary, castor oil were blended in a paste in which nigrosine base as a black dye was dissolved in oleic acid, and kneaded to prepare the following three inks.

  The viscosity is a value measured at a rotational speed of 60 rpm and a measurement temperature of 20 ± 2 ° C. using a B-type viscometer (manufactured by Shibaura System Co., Ltd., single cylinder type rotational viscometer “Bismetron” type VG-A4). .

(Production of ink ribbon)
Nylon 66 fiber (40D-40D general fabric) is knitted into a cylindrical shape in advance, and then slitted to form a seamless endless fabric ribbon having a width of 8 mm and a length of 10 m. 0.5 Pa · s) was impregnated at an impregnation amount of 12.5 g / m ² to produce an endless ink ribbon.

(Production of ink roller)
It is made of a felt, has a disk shape with an outer diameter of 28.5 mm, an inner diameter of 4.5 mm, and a thickness of 9 mm, and an apparent density of 0.26 g / cm ³ , 0.30 g / cm ³ , or 0.33 g / cm ³ One of the three types of roller-shaped porous bodies was impregnated with 3.0 g of any one of the three types of inks A to C to prepare an ink roller.

(Preliminary test)
The ink ribbon 3 is incorporated into the housing 2 shown in FIG. 1, and an ink roller combining the roller and ink shown in Table 2 is set at the position of the ink roller 17, and the ink roller 18 is not set. An ink ribbon cassette 1 for preliminary test was constructed. The ink ribbon cassette 1 is mounted on a dot impact printer of 24 pins (12 pins × 2 rows) and 180 dpi, respectively, and a half-size uppercase letter A to Z of Mincho in draft printing (12 dots × 23 dots) Were sequentially printed until the total number of prints reached 3 million characters, the amount of ink replenished from the ink roller 17 to the ink ribbon 3 was determined. The results are shown in Table 2.

  From the table, it was confirmed that by adjusting the apparent density of the porous body constituting the ink roller and the viscosity of the ink to be impregnated, the replenishment amount of ink per unit printing by the ink roller can be adjusted.

(Examples 1-4, Comparative Examples 1 and 2)
The ink ribbon 3 is assembled in the casing 2 shown in FIG. 1 and ink rollers combining the rollers and ink shown in Table 3 are set at the positions of the ink rollers 17 and 18 to constitute the ink ribbon cassette 1. did.

(Example 5)
A casing 2 is prepared in which the ink roller 17 is fixed in contact with the feed roller 16 and only the ink roller 18 is displaceable between a position separated from the feed roller 16 and a position in contact with the feed roller 16. Then, the ink ribbon cassette 1 was configured by incorporating the ink ribbon 3 into the casing 2 and setting ink rollers, which are combinations of rollers and inks shown in Table 3, at the positions of the ink rollers 17 and 18, respectively. .

  The ink ribbon cassettes 1 of Examples 1 to 5 and Comparative Examples 1 and 2 were mounted on a dot impact printer of 24 pins (12 pins × 2 rows) and 180 dpi, respectively, in draft printing (12 dots × 23 dots). A continuous printing of 26 characters from the Mincho English uppercase letters A to Z was performed. Switching between the ink rollers 17 and 18 is performed when printing of 3 million characters is completed.

  That is, in Examples 1 to 4 and Comparative Examples 1 and 2, in the initial stage from the start of printing to the end of printing of the 3 million characters, the ink roller 17 is brought into contact with the feed roller 16, Ink is supplied to the ink ribbon 3, and thereafter, the ink roller 17 is separated from the feed roller 16, and instead the ink roller 18 is brought into contact with the feed roller 16. Replenished and printed.

  In the fifth embodiment, the ink roller 17 is brought into contact with the feed roller 16 and ink is supplied from the ink roller 17 to the ink ribbon 3 in the initial stage from the start of printing to the end of printing of the 3 million characters. Thereafter, while maintaining the state where the ink roller 17 is in contact with the feed roller 16, the ink roller 18 is further brought into contact with the feed roller 16 and ink is supplied to the ink ribbon 3 from both the ink rollers 17, 18. And printed.

In the ink ribbon cassette 1 of Example 5, the ink replenishment amount W ₁ (g) per unit print number in the initial stage until the printing of 3 million characters by the ink roller 17 alone was 1.1 g. However, the ink replenishment amount W ₁ ′ per unit print number when the ink replenishment was continued until the printing of 6 million characters was completed only by the ink roller 17 thereafter was 0.6 g.

Therefore, the total amount W ₂ of the ink replenishment amount after switching, combined with the ink replenishment amount W ₂ ′ (= 2.5 g) per unit print number in the ink roller 18 that replenishes ink simultaneously after 3 million characters. Was 2.5 + 0.6 = 3.1 g, and the replenishment amount ratio W ₂ / W ₁ was 2.8.

(With or without oversupply)
The PCS density of the first and 100,000th character prints at the initial stage was measured using a reflection densitometer (Macbeth print contrast meter PCM-II manufactured by Gretag Macbeth, using A filter). Then, the presence or absence of oversupply was evaluated according to the following criteria.
A: The PCS concentration at the 100,000th character is the same as or lower than that at the first character, or even when the concentration is higher than that at the first character, the difference is less than 0.15. Also, no blur or the like was found on the 100,000th character print. No oversupply.
X: The PCS density at the 100,000th character was 0.15 or more higher than that at the first character, and an increase in density was confirmed. In addition, bleeding or the like was observed on the 100,000th character print. There is oversupply.

(Print density of the 3rd million characters)
The PCS density of the print of the 3 million characters immediately before the ink roller switching time was measured using the reflection densitometer, and the print density of the 3 million characters was evaluated according to the following criteria.
○: 0.45 or more. Very good print density.
Δ: 0.40 or more and less than 0.45. Good print density.
X: Less than 0.40. Print density is poor.

(Print density of 6 million characters)
After switching the ink roller, the PCS density of the print of the 6 million characters was measured using the reflection densitometer, and the print density of the 6 million characters was evaluated according to the following criteria.
○: 0.45 or more. Very good print density.
Δ: 0.40 or more and less than 0.45. Good print density.
X: Less than 0.40. Print density is poor.

(Print density of 9 million characters)
Use the reflection densitometer to measure the PCS density for printing 9 million characters set to the expected life of the ink ribbon cassette, and use it by rapidly decreasing the print density near the expected life based on the following criteria. It was evaluated whether or not it was possible to inform the replacement time.
○: Less than 0.25. The concentration drop is rapid, and the user can be surely notified of the replacement time.
Δ: 0.25 or more and less than 0.30. Although the concentration drop is a little gradual, the user can be notified of the replacement time.
X: 0.30 or more. The concentration drop is too gradual and the user cannot be notified of the replacement time.

  The above results are shown in Table 3.

From the table, the apparent density ρ ₁ , ρ _{2 of} the porous body is ρ ₁ = ρ ₂ not satisfying the formula (1), and the viscosity μ ₁ , μ _{2 of the} ink does not satisfy the formula (2) μ ₁ = μ _In Comparative Example 1, which was ₂ , oversupply occurred. In order to suppress the oversupply, the apparent densities ρ ₁ and ρ ₂ and the ink viscosities μ ₁ and μ ₂ were adjusted in order to suppress both the replenishing amounts W ₁ and W ₂ , but the apparent density ρ ₁ still remains. [rho ₂ are in [rho ₁ = [rho ₂ do not satisfy equation (1), and the viscosity of the ink mu _1, mu ₂ is Comparative example 2 was mu ₁ = mu ₂ not satisfying the expression (2), after switching It was found that the print density was greatly reduced. In Comparative Example 2, it was found that the function of notifying the user of the replacement time due to a decrease in concentration after reaching the assumed life was slightly low.

  On the other hand, in all of Examples 1 to 5, printing is continued at a high density close to the initial setting value and good print quality from the initial printing to the assumed life without greatly disturbing the printing density. In addition, after reaching the expected life, it was confirmed that the user can be notified of the replacement time by reducing the print density.

In particular, Examples 1 to 3 and 5 were found to be able to suppress a decrease in printing density until the switching after the ink previously impregnated in the ink ribbon was consumed, compared to Example 4. Also in the fifth embodiment in which ink is replenished simultaneously from a plurality of ink rollers after switching, the ratio W ₂ / W ₁ of the replenishment amount is adjusted to a range satisfying the expression (3), so that It has been found that the same print quality can be obtained and the ink ribbon can be prevented from being damaged.

It is sectional drawing which shows an example of embodiment of the ink ribbon cassette of this invention. It is a graph which shows the example of the relationship between the number of printing and the density of printing when printing is repeated using an ink ribbon cassette.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ink ribbon cassette 3 Ink ribbon 4 Ink supply part 7 Accommodating chamber 9, 10 Passage 13 Print part 17, 18 Ink roller (ink supply body)
19 Support member 24 Switching mechanism

Claims (3)

An ink ribbon cassette that circulates an endless ink ribbon and performs printing, and includes an ink supply unit that supplies ink to the ink ribbon, and the ink supply unit includes a plurality of ink supply members that store ink to be supplied; A switching mechanism for switching an ink supply body for supplying ink to the ink ribbon, and each ink supply body is made of a porous body that can be impregnated with ink, and each ink supply body has the following (a ) And (b):
(a) The apparent density ρ ₁ (g / cm ³ ) of the porous body forming the ink supply body selected in the initial stage from the start of use of the ink ribbon cassette to the switching by the switching mechanism, and the switching by the switching mechanism The apparent density ρ ₂ (g / cm ³ ) of the porous body forming the ink supply body selected by the formula (1):
ρ ₁ > ρ ₂ (1)
In a relationship,
(b) The viscosity μ ₁ (Pa · s) of the ink impregnated in the ink supply body selected in the initial stage and the viscosity μ _{2 of the} ink impregnated in the ink supply body selected by switching by the switching mechanism. (Pa · s) is the formula (2):
μ ₁ > μ ₂ (2)
In a relationship,
An ink ribbon cassette characterized by satisfying at least one of the conditions. The ratio W ₂ / W ₁ between the ink replenishment amount W ₁ (g) per unit print number in the initial stage and the ink replenishment amount W ₂ (g) per unit print number after switching is expressed by the formula ( 3):
1.2 ≦ W ₂ / W ₁ ≦ 3.0 (3)
The ink ribbon cassette according to claim 1, wherein   3. The ink ribbon cassette according to claim 1, wherein the ink replenishing unit includes a switching mechanism that performs switching in order to select any one of a plurality of ink replenishers and replenish ink to the ink ribbon.

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