JPH09314965A - Ink supply structure for ink ribbon - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] There is no printing failure due to bleeding or the like at the start of use, and it is possible to easily grasp the replacement time of the ink ribbon. A fabric ink ribbon is configured to be continuously replenished with liquid ink, and a print density decay curve F of the fabric ink ribbon that changes with an increase in the total number of prints is expressed by the following formula [A] and The density and material of the ink impregnated body and the viscosity of the liquid ink are set so as to satisfy the relationship of the formula [B]. P (x) ≦ 1.1 × P
[A], 0.5 × G × L <S <G × L ... [B], P (x)
: Print density value (vertical axis direction), P: print density value at initial printing, a: preset lower limit of print density, G: print at initial printing on the graph showing print density decay curve F Apparent size from the density value P to the lower limit value a, L: Apparent size of the total number of prints until the print density value on the graph showing the print density attenuation curve F becomes a, S: Print density An area of a portion surrounded by a horizontal line parallel to the horizontal axis passing through P (x) = a on the graph showing the attenuation curve F, the vertical axis, and the print density attenuation curve F.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink replenishing structure for a fabric ink ribbon provided in an ink ribbon cassette or the like which is detachably attached to a printing device such as an impact type serial printer. The ink impregnated body, which is impregnated with the liquid ink in the storage portion, is brought into contact with the fabric ink ribbon directly or indirectly via an ink transfer roll, and the liquid ribbon is continuously replenished with the liquid ink. The present invention relates to a structure for supplying ink to an ink ribbon.

[0002]

2. Description of the Related Art In an ink replenishing structure for an ink ribbon of this type, its density is changed according to the material of the ink impregnated body.
If the density is set to maximize the amount of ink pumped per unit time, the amount of ink pumped per unit time at the beginning of use when the predetermined amount of liquid ink is filled in the ink reservoir becomes very large, and the ink ribbon Excessive supply to the ink causes printing defects such as bleeding of the print, and the liquid ink in the ink storage portion is rapidly consumed, and the ink storage portion is discharged at an early stage before the ink ribbon reaches the durable print count (lifetime). Must be replaced. Therefore, conventionally, based on experience, the density of the ink impregnated body has been set to a density smaller than the density at which the ink pumping amount per unit time is maximum.

[0003]

According to the above conventional ink replenishing structure, since the density of the ink impregnated body is designed based on the experience of the engineer, the ink impregnated body is lacked due to lack of experience of the engineer. If the density of the ink becomes too small, the amount of ink drawn up per unit time by the ink impregnator is small, so printing defects such as bleeding at the start of use can be suppressed, but the consumption of the liquid ink filled in the ink reservoir Since the speed is slow, the print density is generally low from the beginning of use, and the print density does not reach the preset lower limit of the print density even when the number of durable prints of the ink ribbon is exceeded. The ink ribbon will be damaged during printing due to the delay in the replacement time, and as a result, it will print directly on the paper, causing damage to the print head and shortening the head life. There was a problem.

Therefore, the inventor of the present application pays attention to the print density attenuation curve, and first, the ink impregnation is carried out so that the print density attenuation curve satisfies the relationship of G × L <S. A printing experiment was conducted by setting the density of the body, the material, and the viscosity of the liquid ink (details will be described in Comparative Example 1 in Examples below). In this case, as shown in FIG. 6 and [Table 1], the print density during use exceeded the allowable range and became higher than the initial print density. This is because the liquid ink was excessively supplied to the ink ribbon, which caused printing stains and bleeding.

Next, the density, the material and the liquid ink of the ink impregnated body are set so that the print density attenuation curve satisfies the relationship of 0.5 × G × L> S ... [D]. A printing experiment was conducted by setting the viscosity (details will be described in Comparative Examples 2 and 4 in Examples described later). In this case, as shown in FIG. 7 and [Table 1] and FIG. 13 and [Table 2], the concentration was extremely lowered from the beginning of use, and the readable low concentration was maintained. As a result, the user (operator) thinks that the user can print as much as he wants, and the printing is continued, which causes the damage of the ink ribbon material and shortens the life of the print head.

Further, although the print density attenuation curve satisfies the relationship of 0.5 × G × L <S <G × L ... [B], the print density during use is within an allowable range (1. A printing experiment was carried out by setting the density and material of the ink impregnated body and the viscosity of the liquid ink so that the density would exceed 1 × P) (Comparative Example 3 in Examples described later in detail).
It describes in. ). In this case, as shown in FIG. 12 and [Table 2], the liquid ink is excessively supplied to the ink ribbon at the portion where the print density during use exceeds the allowable range, and print stains or bleeding may occur. It was the cause of the invitation.

As a result of further diligent research on the basis of the above experimental results, the present inventor has found that on the graph showing the print density attenuation curve, the print density value during initial printing and the maximum print density value during use. , And that there is a special relationship between the preset lower limit of the print density and the area surrounded by the print density attenuation curve, and based on this finding, an improvement in the ink supply structure to the ink ribbon As a result, there is no printing defect due to bleeding at the start of use, and the time to replace the ink ribbon can be easily grasped.

[0008]

In order to achieve the above object, a characteristic constitution of an ink replenishing structure for an ink ribbon according to claim 1 of the present invention is such that the total number of prints is increased in the constitution mentioned above. The density and material of the ink impregnated body and the viscosity of the liquid ink are set so that the print density attenuation curve of the fabric ink ribbon that changes with time satisfies the relationship of the following expressions [A] and [B]. There is a point. P (x) ≤ 1.1 x P ... [A] 0.5 x G x L <S <G x L ... [B] P (x): Print density value (vertical axis direction) P: print density value at initial printing a: preset lower limit value of print density G: apparent density from print density value P at initial printing to the lower limit value a on the graph showing the print density attenuation curve Dimension L: Apparent size of the total number of prints until the print density value on the graph showing the print density attenuation curve becomes a S: Passing P (x) = a on the graph showing the print density attenuation curve Area of a portion surrounded by a horizontal line parallel to the horizontal axis, a vertical axis, and a print density attenuation curve According to the above characteristic configuration, for example, FIGS. 3 to 5 and [Table 1], and FIGS. As shown in [Table 2], the print density is within the allowable range (1.1 × P) after the start of use.
Since it does not darken beyond the range, it is difficult for printing defects such as bleeding of printing due to excessive supply of liquid ink to occur.
When the density decay curve is close to the readable lower limit of the print density, the gradient of the print density change curve becomes larger than that of the one satisfying the above expression [D]. It becomes easier to check. Therefore, it becomes easy to know when to replace the ink ribbon, and it is possible to prevent the life of the print head from being shortened due to damage to the ribbon material. Moreover, it is possible to judge the quality of the print density attenuation curve by mathematical judgment on the graph showing the print density attenuation curve. Compared with the print density decay curve,
Compared with empirical judgment as to whether or not the print density decay curve measured based on this experiment is included in the ideal print density curve, even an inexperienced engineer can accurately determine whether the print density decay curve is acceptable or not. Came to be able to judge.

According to a second aspect of the present invention, there is provided a characteristic structure of an ink replenishing structure for an ink ribbon, wherein the ink impregnated body is composed of an open-cell polyurethane foam and has a density of 0.24 g / cm ³ or more. , 0.38 g / cm ³ or less. That is, the present inventor:
As a result of researching the ink impregnated body according to claim 1,
When the ink impregnation body is composed of an open-cell polyurethane foam, if the density of the ink impregnation body is less than 0.24 g / cm ³ , the ink pumping performance is too high. In addition to the excessive supply of liquid ink, the supply amount of the liquid ink sharply decreases after the excess supply, and in the range where the density of the ink impregnated body exceeds 0.38 g / cm ³ , It was found that the ink pumping performance deteriorates and the liquid ink cannot be sufficiently supplied to the fabric ink ribbon immediately after the start of use. Therefore,
The ink impregnated body is composed of an open-celled polyurethane foam, and the lower limit of the density of the ink impregnated body is 0.24 g / cm ³ so as to be advantageous in terms of ink pumping performance,
Moreover, since the upper limit is set to 0.38 g / cm ³ ,
After that, the viscosity of the liquid ink may be set based on an experiment so that the print density attenuation curve satisfies the above expressions [A] and [B]. The material of the ink impregnation body, the density, and the liquid ink The ink supply structure can be designed quickly and easily as compared with the case where all the viscosities are set based on experiments. Furthermore, in order to obtain the density of the ink impregnated body advantageous in terms of ink pumping performance in advance, it is not necessary to provide the ink impregnated body made of the open-cell polyurethane foam with a special adjusting mechanism for adjusting the density. Therefore, the structure of the ink supply structure can be simplified.

A characteristic configuration of the ink replenishing structure for the ink ribbon according to claim 3 of the present invention is that the viscosity of the liquid ink is set within a range of 150 cps or more and 1000 cps or less. That is, the present inventor has the above-mentioned claim 1.
As a result of studying the viscosity of the liquid ink described in 1., the viscosity of the liquid ink is weak in a range where the viscosity of the liquid ink is lower than 150 cps, so that the liquid ink easily flows in the ink impregnated body, and the fabric ink immediately after the start of use. The liquid ink is excessively supplied to the ribbon, and after the excessive supply, the supply amount of the liquid ink sharply decreases.
In the range where the viscosity of the liquid ink exceeds 1000 cps,
Since the liquid ink has a high viscosity, it is difficult for the liquid ink to flow through the ink impregnated body, and it has been found that the liquid ink cannot be sufficiently supplied to the fabric ink ribbon immediately after the start of use. Therefore, the lower limit of the viscosity of the liquid ink is set to 150 cps in advance so that the viscosity of the ink is advantageous.
Since the upper limit is set to 1000 cps, the material and density of the ink impregnated body are set based on the experiment so that the print density attenuation curve may satisfy the above expressions [A] and [B]. The material of the ink impregnation body,
The ink replenishment structure can be designed quickly and easily as compared with the case where the density and the viscosity of the liquid ink are all set based on experiments.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 shows an endless ink ribbon cassette which is equipped with an ink supply structure for an ink ribbon according to the present invention and is detachably attached to a printing device such as an impact type serial printer. In the cassette case 1 equipped with the guide arms 1A and 1B for traveling,
A pair of drive feed rolls 2A and driven feed rolls 2 which drive and run the endless belt-shaped fabric ink ribbon R impregnated with liquid ink in advance while being held.
B, a ribbon accommodating portion 3 for accommodating most of the ink ribbon R sandwiched between the two feed rolls 2A and 2B and sent out in a fan-hold state in a folded state, and in the cassette case 1 Is provided with an ink storage section 4 for storing the liquid ink supplied to the ink ribbon R. The ink storage section 4 is loaded with an ink occlusion body 5 composed of a nonwoven fabric that can be impregnated with a liquid ink, a fiber bundle, or a sponge such as an open-cell polyurethane foam. Liquid ink (reserved ink) stored in the ink storage section 4 is stored. Further, an ink impregnation body 6 is loaded in the ink storage section 4. The ink storage section 4
One end side of the ink impregnated body 6 located inside is in contact with one side surface of the ink occlusion body 5 and an opening 8A formed in the peripheral wall 8 forming the ink storage portion 4 is formed.
The other end side of the ink impregnated body 6 protruding from the driven feed roll 2B side is in contact with the outer peripheral surface of the driven feed roll 2B. That is, the ink storage body 5 is impregnated with the stored liquid ink, in other words, the pumped ink impregnation body 6 is indirectly contacted with the fabric ink ribbon R via the driven feed roll 2B,
The ink ribbon R is configured to be continuously replenished with liquid ink. Therefore, the driven feed roll 2
B indirectly contacts the ink impregnation body 6 and the fabric ink ribbon R, and continuously replenishes the running fabric ink ribbon R with the liquid ink drawn up from the ink storage body 5 by the ink impregnation body 6. It is also used as an ink transfer roll.

In the ink replenishing structure for the ink ribbon thus constructed, for example, as shown in FIG. 2, the print density attenuation curve F of the fabric ink ribbon R which changes with an increase in the total number of prints is lowered. Formula [A] and the following formula [B]
So as to satisfy the relationship of
Also, the viscosity of the liquid ink is set. P (x) ≤ 1.1 x P ... [A] 0.5 x G x L <S <G x L ... [B] P (x): Print density value (vertical axis direction) P: print density value at initial printing a: preset lower limit of print density G: apparent density from print density value P at initial printing on the graph showing the print density attenuation curve F to the lower limit value a Dimension L: Apparent dimension of the total number of prints until the print density value on the graph showing the print density attenuation curve F becomes a S: P (x) = on the graph showing the print density attenuation curve F a
Area of a portion surrounded by a horizontal line parallel to the horizontal axis passing through, the vertical axis, and the print density attenuation curve F

The print density attenuation curve F is, for example,
It can be measured by using PCM-2 (A filter) manufactured by Macbeth, and in this case, the lower limit value a of the preset print density (PCS value) (generally, the use limit print density set in the printer design is used. The value) is 0.3.

Specifically, the ink impregnated body 6 is composed of an open-celled polyurethane foam, and the density thereof is set within the range of 0.24 g / cm ³ or more and 0.38 g / cm ³ or less. In addition, the viscosity of the liquid ink is set to 350 cps.

[Second Embodiment] In the endless ink ribbon cassette of the first embodiment, the ink impregnated body 6 may be made of wool felt. In this case, the print density attenuation curve F of the fabric ink ribbon R, which changes as the total number of prints increases, is expressed by the following equation [A] and the following equation [B].
The density of the ink impregnated body 6 is set to 0.48 so that the relationship of
with some set to g / cm ^3, a viscosity of the liquid ink 150cps or more, within the following 1000 cps, preferably above 200 cps, is set within the following ranges 800 cps. P (x) ≤ 1.1 x P ... [A] 0.5 x G x L <S <G x L ... [B] P (x): Print density value (vertical axis direction) P: print density value at initial printing a: preset lower limit of print density G: apparent density from print density value P at initial printing on the graph showing the print density attenuation curve F to the lower limit value a Dimension L: Apparent dimension of the total number of prints until the print density value on the graph showing the print density attenuation curve F becomes a S: P (x) = on the graph showing the print density attenuation curve F a
The area of a portion surrounded by a horizontal line parallel to the horizontal axis passing through, the vertical axis and the print density attenuation curve F is the same as that of the first embodiment.

[Other Embodiments] In the first embodiment, the viscosity of the liquid ink is not limited to 350 cps, and the viscosity of the liquid ink is in the range of 150 cps to 1000 cps, preferably 200 cps. Above, 800c
If it is within the range of ps or less, it can be appropriately changed. In the second embodiment, is not limited to 0.48 g / cm ³ as the density of the ink absorbing member 6, as the density of the ink absorbing member 6 0.40 g / cm ³
As described above, if it is within the range of 0.60 g / cm ³ or less, it can be appropriately changed. In the first embodiment, the ink impregnation body 6 is configured to indirectly contact the ink ribbon R via the driven feed roll 2B to continuously replenish the ink ribbon R with the liquid ink. The configuration is not limited to this, and the ink impregnation body 6 may be configured to directly contact the ink ribbon R to continuously replenish the ink ribbon R with the liquid ink. Separately from the feed roll 2B, a dedicated ink transfer roll for continuously replenishing the running ink ribbon R with the liquid ink is provided, and the ink impregnation body 6 is indirectly contacted with the ink ribbon R via the ink transfer roll. It may be configured so as to allow it. When the ink occlusion body 5 is composed of an open-cell polyurethane foam made of the same material as the ink impregnation body 6, the ink occlusion body 5 may be integrally formed with the ink impregnation body 6. In the first embodiment, the ink ribbon cassette provided with the ink replenishing structure of the present invention has been described, but if the fabric ink ribbon R has a structure capable of continuously replenishing liquid ink, the ink ribbon cartridge It is not limited to the ink supply structure of the set. In the first embodiment, the case where the technique of the present invention is applied to the ink replenishing structure for the ink ribbon of the endless ink ribbon cassette has been described. However, the fabric ink ribbon is reciprocally used by reversing the printer. It may be applied to the ink replenishing structure for the fabric ink ribbon of the ink ribbon cassette which can be used.

[0017]

EXAMPLE The ink ribbon cassette of the first embodiment was subjected to a printing experiment by changing the density of the ink impregnated body 6 under the following conditions, and as a result, as shown in each graph of FIGS. The relationship between the total number of prints and the print density attenuation curve F could be obtained. The print density value P (x) is P made by Macbeth.
Numerical value measured using CM-2 (A filter) (PCS
Value), and the lower limit of the print density according to this measuring method is 0.3. The print pattern is ANK (alphanumeric)
It was printed. In [Table 1], the area S, G × L, and 0.
5 × G × L is a numerical value measured in each of the above graphs with the width of the change value 1.0 of the print density in the vertical axis direction being 1 and the number of prints in the horizontal axis direction being 100,000 characters being 1. Show. [Example 1] FIG. 3 shows a case where the printing experiment was performed using an ink impregnated body 6 made of an open-celled polyurethane foam having a density of 0.24 g / cm ³ and a liquid ink having a viscosity of 350 cps. A graph is shown. Corresponding this graph with [Table 1], the area S of a portion surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, a vertical axis and a print density attenuation curve, The numerical value of 0.5 × G × L and the numerical value of G × L satisfy the above equations [A] and [B], and the print density during use is within the allowable range (1.1 × P). ), It is difficult for printing defects such as bleeding of printing due to excessive supply of liquid ink to occur, and when the density decay curve approaches the lower limit of printing density, the above formula [D] is used. Compared to the case where the density is set to satisfy the above condition, the gradient of the change curve of the print density becomes large, so that it is easy to visually confirm the decrease in the print density.

Example 2 In FIG. 4, the density is 0.31 g /
7 is a graph showing a case where the printing experiment is performed using an ink impregnated body 6 made of an open-cell polyurethane foam having a cm ³ and a liquid ink having a viscosity of 350 cps. Corresponding this graph with [Table 1], the area S of a portion surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, a vertical axis and a print density attenuation curve, The numerical value of 0.5 × G × L and the numerical value of G × L satisfy the above equations [A] and [B], and the print density during use is within the allowable range (1.1 × P). ), It is difficult for printing defects such as bleeding of printing due to excessive supply of liquid ink to occur, and when the density decay curve approaches the lower limit of printing density, the above formula [D] is used. The density of the change curve of the print density is larger than that of the density that satisfies
It becomes easy to visually confirm a decrease in print density.

[Embodiment 3] FIG. 5 shows 0.38 g / cm ^3.
Ink impregnation body 6 made of open-cell polyurethane foam
And a graph in the case where the printing experiment is performed using a liquid ink having a viscosity of 350 cps. Corresponding this graph with [Table 1], the area S of a portion surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, a vertical axis and a print density attenuation curve, Numerical value of 0.5 × G × L,
The numerical value of G × L satisfies the above formulas [A] and [B], and the print density during use is within the allowable range (1.1
XP) and does not become darker, so printing defects such as bleeding of printing due to excessive supply of liquid ink are less likely to occur,
Also, when the density decay curve approaches the lower limit of print density,
Compared with the density which satisfies the above formula [D],
Since the gradient of the print density change curve becomes large, it becomes easy to visually confirm the decrease in print density.

Comparative Example 1 FIG. 6 shows that the density is 0.20 g /
7 is a graph showing a case where the printing experiment is performed using an ink impregnated body 6 made of an open-cell polyurethane foam having a cm ³ and a liquid ink having a viscosity of 350 cps. Corresponding this graph with [Table 1], the area S of a portion surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, a vertical axis and a print density attenuation curve, The numerical value of 0.5 × G × L and the numerical value of G × L satisfy the above formula [C], and the print density during use exceeds the allowable range (1.1 × P) and becomes dark. . This is because the liquid ink is excessively supplied to the ink ribbon, which causes printing stains and bleeding, and the liquid ink in the ink storage portion 4 is rapidly consumed, so that the life of the ink ribbon cassette is shortened. Is also not preferable as the density of the ink impregnated body 6.

Comparative Example 2 In FIG. 7, the density is 0.40 g /
7 is a graph showing a case where the printing experiment is performed using an ink impregnated body 6 made of an open-cell polyurethane foam having a cm ³ and a liquid ink having a viscosity of 350 cps. Corresponding this graph with [Table 1], the area S of a portion surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, a vertical axis and a print density attenuation curve, The numerical value of 0.5 × G × L and the numerical value of G × L satisfy the above formula [D], causing an extreme decrease in concentration from the initial stage of use, and a readable low concentration was maintained. As a result, the user (operator) thinks that he / she can print as much as he / she wants to continue printing, which causes the damage of the ink ribbon material to shorten the life of the print head, which is not preferable as the density of the ink impregnated body 6. .

[0022]

[Table 1]

Next, the ink ribbon cassette of the second embodiment was subjected to a printing experiment by changing the viscosity of the liquid ink under the following conditions. As a result, as shown in the graphs of FIGS. The relationship between the total number of prints and the print density attenuation curve F could be obtained. The print density value P (x) is a numerical value (P which is measured using PCM-2 (A filter) manufactured by Macbeth Co., Ltd.
CS value), and the lower limit of the print density by this measuring method is 0.3. The printing pattern was ANK (alphanumeric) printing. In [Table 2], the area S, G × L, and 0. 0 of a portion surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, the vertical axis, and the print density attenuation curve. 5 × G × L is a numerical value measured in each of the above graphs with the width of the change value 1.0 of the print density in the vertical axis direction being 1 and the number of prints in the horizontal axis direction being 100,000 characters being 1. Show.

Example 4 FIG. 8 shows that the density is 0.48 g /
cm ³ wool felt ink impregnation body 6 and viscosity 2
The graph when the said printing experiment was conducted using the liquid ink of 00 cps is shown. And this graph and [Table 2]
And the area S of a part surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, the vertical axis and the print density attenuation curve, and a numerical value of 0.5 × G × L. , G × L satisfy the above equations [A] and [B],
Since the print density during use does not exceed the permissible range (1.1 × P) and becomes dark, print defects such as print bleeding due to excessive supply of liquid ink are less likely to occur, and the density decay curve is When the lower limit of the print density is approached, the above [D]
Compared to the case where the density is set to satisfy the formula, the gradient of the change curve of the print density becomes large, so that it is easy to visually confirm the decrease in the print density.

[Embodiment 5] FIG. 9 shows that the density is 0.48 g /
cm ³ wool felt ink impregnation body 6 and viscosity 4
The graph when the said printing experiment was conducted using the liquid ink of 00 cps is shown. And this graph and [Table 2]
And the area S of a part surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, the vertical axis and the print density attenuation curve, and a numerical value of 0.5 × G × L. , G × L satisfy the above equations [A] and [B],
Since the print density during use does not exceed the permissible range (1.1 × P) and becomes dark, print defects such as print bleeding due to excessive supply of liquid ink are less likely to occur, and the density decay curve is When the lower limit of the print density is approached, the above [D]
Compared to the case where the density is set to satisfy the formula, the gradient of the change curve of the print density becomes large, so that it is easy to visually confirm the decrease in the print density.

[Sixth Embodiment] FIG. 10 shows that the density is 0.48 g.
2 is a graph showing a case where the above-mentioned printing experiment was performed using an ink impregnated body 6 made of wool felt of / cm ³ and a liquid ink having a viscosity of 500 cps. Corresponding this graph with [Table 2], the area S of a portion surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, a vertical axis and a print density attenuation curve, The numerical value of 0.5 × G × L and the numerical value of G × L satisfy the above equations [A] and [B], and the print density during use is within the allowable range (1.1 × P). ), It is difficult for printing defects such as bleeding of printing due to excessive supply of liquid ink to occur, and when the density decay curve approaches the lower limit of printing density, the above formula [D] is used. Compared to the case where the density is set to satisfy the above condition, the gradient of the change curve of the print density becomes large, so that it is easy to visually confirm the decrease in the print density.

[Embodiment 7] FIG. 11 shows a density of 0.48 g.
³ is a graph showing a case where the printing experiment is performed using an ink impregnated body 6 made of wool felt of / cm ³ and a liquid ink having a viscosity of 800 cps. Corresponding this graph with [Table 2], the area S of a portion surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, a vertical axis and a print density attenuation curve, The numerical value of 0.5 × G × L and the numerical value of G × L satisfy the above equations [A] and [B], and the print density during use is within the allowable range (1.1 × P). ), It is difficult for printing defects such as bleeding of printing due to excessive supply of liquid ink to occur, and when the density decay curve approaches the lower limit of printing density, the above formula [D] is used. Compared to the case where the density is set to satisfy the above condition, the gradient of the change curve of the print density becomes large, so that it is easy to visually confirm the decrease in the print density.

Comparative Example 3 FIG. 12 shows that the density is 0.48 g.
6 is a graph showing a case where the above-mentioned printing experiment was performed using an ink impregnated body 6 made of wool felt of / cm ³ and a liquid ink having a viscosity of 60 cps. And this graph and [Table 2]
And the area S of a part surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, the vertical axis and the print density attenuation curve, and a numerical value of 0.5 × G × L. , G × L satisfy the above formula [B], but the print density during use exceeded the allowable range (1.1 × P) and became dark. This is because the liquid ink is excessively supplied to the ink ribbon, which causes printing stains and bleeding, and the liquid ink in the ink storage portion 4 is rapidly consumed, so that the life of the ink ribbon cassette is shortened. It also causes a shortage, which is not preferable as the viscosity of the liquid ink.

Comparative Example 4 In FIG. 13, the density is 0.48 g.
6 is a graph showing a case where the printing experiment is performed using an ink impregnated body 6 made of wool felt of / cm ³ and a liquid ink having a viscosity of 1200 cps. Corresponding this graph with [Table 2], the area S of a portion surrounded by a horizontal line parallel to the horizontal axis passing through the lower limit value 0.3 of the print density, a vertical axis and a print density attenuation curve, The numerical value of 0.5 × G × L and the numerical value of G × L satisfy the above formula [D], causing an extreme decrease in concentration from the initial stage of use, and a readable low concentration was maintained. As a result, since the user (operator) thinks that he can print as much as he wants, the printing is continued, which causes the damage of the ink ribbon material and shortens the life of the print head, which is not preferable as the viscosity of the liquid ink.

[0030]

[Table 2]

In the claims, reference numerals are provided for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the attached drawings by the entry.

[Brief description of drawings]

FIG. 1 is a partially cutaway sectional view of an ink ribbon cassette according to a first embodiment of the present invention.

FIG. 2 is an example of a conceptual diagram of a graph showing a print density attenuation curve of the present invention.

FIG. 3 is a graph of a printing experiment in Example 1 of the present invention.

FIG. 4 is a graph of a printing experiment in Example 2 of the present invention.

FIG. 5 is a graph of a printing experiment in Example 3 of the present invention.

FIG. 6 is a graph of a printing experiment in Comparative Example 1.

FIG. 7 is a graph of a printing experiment in Comparative Example 2.

FIG. 8 is a graph of a printing experiment in Example 4 of the present invention.

FIG. 9 is a graph of a printing experiment in Example 5 of the present invention.

FIG. 10 is a graph of a printing experiment in Example 6 of the present invention.

FIG. 11 is a graph of a printing experiment in Example 7 of the present invention.

FIG. 12 is a graph of a printing experiment in Comparative Example 3.

FIG. 13 is a graph of a printing experiment in Comparative Example 4.

[Explanation of symbols]

 2B Ink transfer roll (following feed roll) 4 Ink storage part 6 Ink impregnation body F Printing density decay curve R Fabric ink ribbon

Claims (3)

[Claims] 1. An ink impregnated body (6) impregnated with a liquid ink in an ink storage portion (4) is brought into contact with a fabric ink ribbon (R) directly or indirectly via an ink transfer roll (2B). An ink replenishing structure for an ink ribbon configured to continuously replenish the ink ribbon (R) with a liquid ink, wherein the fabric ink ribbon (R) changes as the total number of prints increases The print density decay curve (F) of the following formula [A]
And an ink replenishing structure for the ink ribbon in which the density and material of the ink impregnated body (6) and the viscosity of the liquid ink are set so as to satisfy the relationship of the following formula [B]. P (x) ≤ 1.1 x P ... [A] 0.5 x G x L <S <G x L ... [B] P (x): Print density value (vertical axis direction) P: print density value at initial printing a: preset lower limit value of print density G: from print density value P at initial printing on the graph showing the print density attenuation curve (F) to the lower limit value a Apparent dimension L: Apparent dimension of the total number of prints until the print density value becomes a on the graph showing the print density attenuation curve (F) S: On the graph showing the print density attenuation curve (F) P (x)
= Area of a portion surrounded by a horizontal line parallel to the horizontal axis passing through a, a vertical axis, and a print density attenuation curve (F) 2. The ink impregnated body (6) is composed of an open-cell polyurethane foam and has a density of 0.
The ink replenishing structure for an ink ribbon according to claim 1, wherein the ink replenishing structure is set in a range of 24 g / cm ³ or more and 0.38 g / cm ³ or less. 3. The ink replenishing structure for an ink ribbon according to claim 1, wherein the viscosity of the liquid ink is set in a range of 150 cps or more and 1000 cps or less.