JPS5853473A - ink container - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Akira Kinki was involved in printing equipment that uses solution ink.

In particular, the ink pulse type inkjet printing system, which involves an ink container that suppresses ink evaporation, is suitable for small-sized printing devices because it is easy to manufacture and consumes little energy. In particular, this advantage can be taken advantage of if it is used in a portable device that is powered by batteries. However, as devices become smaller, the ink containers inevitably become smaller. 1. Ink bags made of strong and thick film such as vinylidene salt, which are commonly used, have a large negative pressure as the ink is consumed. If the ink becomes too large, it becomes impossible to use up all the ink in the ink container. Unfortunately, small ink containers are thin,
It is necessary to protect the weak ink bag. However, weak materials generally have a high gas permeability, and since a thin film is used, gases can permeate even more easily. In the case of commonly used water-soluble inks, the ink density decreases due to water evaporation, making it impossible to eject the ink. In addition, if a film such as polyethylene or polypropylene, which has a relatively low water permeability and a high air permeability, is used, for example, at a high temperature of 60°C, the air in the ink bag will be absorbed by the water vapor. The pressure drops and the 9 qi invades from outside. There is a problem in that the ink bag eventually ruptures due to the intrusion of air.

Therefore, an object of the present invention is to provide an ink container that can use up all the ink.

Another purpose of the book is to suppress ink evaporation.

Yet another purpose of this invention is to prevent the ink bag from bursting.

Figure 1 shows an embodiment of the invention, 1 is a high-density polyethylene or polypropylene ink container base, 2ti
A film made of low-density polyethylene with a thickness of 50μ heat-fused to the base 1, a lid member made of the same material as the 5Fi base 1, 4 a thin tube for ventilation formed by the base 1 and the lid member 5, 5
is a rubber plug through which a connecting needle for supplying ink to the print head (not shown) passes.

In the implementation of No. 11g, the thin tube 4 for ventilation is made thinner,
The length of the capillary tube 4 is selected to suppress evaporation of the ink by increasing the length, and the pressure drop caused by the air flow passing through the capillary tube 4j during ink ejection does not adversely affect ink ejection. be.

A printing device not shown in the embodiment of FIG.
When the ink container is set and ink is ejected, the pressure drop ΔP when air is supplied through the thin tube 4 is as follows.

・However, η: Air viscosity (Pa・s), /: Capillary length (
m), v: flow velocity (m/s) & 6: capillary diameter (
1).

Here, the flow velocity M is increased from the ink consumption velocity Q (l//8). Therefore, it follows from formulas ■ and ■.゛Next, the conditional expression for the amount of diffusion of vapor exiting from the inside of the ink container 2 to the outside through the thin tube 5 will be discussed.

The amount of diffused vapor J, C11) is generally ΔC ΔX -where D: Diffusion coefficient (s//s) ΔC7Δx: Concentration gradient (l14/-') t: Time (s), 82 area [♂] It's rumored.

1ζ where Δ0'', p: vapor density (Kf/,
/) Δxllll! Substituting B−π(11/4 into the formula ■).

becomes.

Based on the large numerical formula mentioned above, the limit negative pressure at the time of ink ejection can be determined by
P&], then from formula 2 ■.

Also, the allowable ink evaporation rate per unit time.

If B (K da / 8), then from 1 set ■ becomes. Therefore, the length l and diameter d of the tubule are expressed as:

If the formula is selected so that the formula holds true, the negative pressure during ink ejection will not have an adverse effect, and there will be no problem of ink evaporation.

Due to the characteristics of the inkjet head, there are limits to negative pressure.
The limit of the total amount of water vapor that diffuses through the air intake port and exits also changes depending on the capacity of the ink container. Therefore, regarding the dimensions of the 9 air intake tubes of Honjutsu, -
It is not possible to determine the range generally; it is necessary to substitute each condition into the above formula to determine the range of the length and diameter ratio of the 2P air intake capillary tube, and then determine the dimensions of the capillary tube. There is.

For example, the critical negative pressure is usually less than 20 cm1i, and if it is greater than this, printing becomes impossible.

If you want to improve printing responsiveness, it is desirable to set it to 5QcstHsO or less.The viscosity η of air changes depending on the temperature, and at 0°C to 60°C, it is 1017 to α02001)? Take. Ink consumption rate flit, for example, ink droplet diameter 100
When injected with μ at 500Hg.

4π(50X10”)”X500-2.6X1
0-'1//s5, which is the case when a multi-nozzle head with 52 nozzles is used to eject ink droplets with a diameter of 80 μ at a frequency of 5 KHz.

The allowable value for ink evaporation increases when the ink tank capacity is large and the initial ink density is made thin. For example, in an ink that can print up to a dye density of 2 inches, the initial dye production is 1 inch and the ink tank capacity is 1 inch.
In the case of 008, about 5 tons of ink solvent is allowed to evaporate. If the ink storage period is half a year, the allowable ink evaporation rate lfB is 86400△7axtsoa 8
becomes. Conversely, if the ink tank capacity is 1 (7), the ink production increase is only allowed to increase by 5, and the ink storage period is one year.

86400BId Xj65(l
It becomes a.

The multiplication coefficient is expressed as 275 p from the value Ds at 760 If, T: absolute temperature 1f, p: pressure (W Hl), and fc is the diffusion coefficient Do of water vapor and 9 air.
= a22cm"/e, at 0°C D -2,
2×10-” di8, which is 75 at 60°C.

Vapor-tight IfFi, fC is 0 for water-soluble ink.
'CfFi, p・-[Lo 049KIl/dte h60''c, it is considered that ρ=α15Kf/l/.

In formula (■), assuming that ink is ejected under a temperature of 0°C, Mu-20crnHsO-w1960Paya-Q, 01
7 apm 1.7X10-”pa ・5Q-26X
If it is 1rJ1@diB.

i, I
mFImaro0-490pa Wm(10200-490paW'pa68Q"2
．． 6XID-”dig and hba2.5X10”
≧ −・・・・・・・・・■6.

In the equation, Dsm2.2XI D-' dig, pm (LOO
49 Kf/s/, B = X2 X 10-”m”, p-El
If 15Kg/dB■t6x1o"""jl/s, then t7xto@≦I-, -・,,...

becomes.

As mentioned above, the relationship between l and d takes various values depending on the conditions.
KHff is the injection 11,5 so-called HsOO negative pressure limit, h
The shaded area 10 indicates the allowable range of the diameter d and length l of the capillary when ink evaporation at 60° C. is allowed for α1v per year.

Also, 0℃, 100μ ink ff 24 nozzles.

The permissible range of the capillary diameter d and length l when the injection frequency is 2 KHz and the permissible evaporation amount f1f for one year is indicated by a diagonal line 11.

As mentioned above, since ink evaporation is prevented by the thin tube 4, the water inside and outside the film 2 is almost saturated, and even if the air pressure is equal to f and one film 2 is made of polyethylene, it will not burst. Also, if the film is about SOμ, it is weak and ink can be used until after 1Ik. It is even better if the film 2 is formed into a shape that lines up with the base 11f by 9-shape molding or the like.

In addition, if a laminated film such as a saponified ethylene vinyl acetate copolymer is used as the film, it will be much better in terms of evaporation and air permeation.In the examples described above, the thin tube was a circular tube, but other cross-sectional shapes can also be used. Appropriate dimensions can be found by considering a circular pipe. Also, instead of one thin tube, it may be used as a mutual thin tube. In this case, the permissible range of Kai and l will be narrower than in the case of one tube.

Further, a stainless steel tube or the like may be used as the thin tube, and if it is formed by a groove 21 provided on the edge of the base body 1 and a lid 5 as shown in FIG. 5, four tubes are formed. Reference numeral 22 denotes a ventilation hole that opens one end of the groove 21 to the outside air.

In each of the embodiments described above, evaporation is suppressed by long and thin ventilation holes, but ventilation holes may be provided that are cut off from outside air except during injection.

As can be seen from the embodiments described above, according to one example, an ink container made of a thin film is used.

Furthermore, by covering the ink with a container to prevent evaporation, even a small ink container can be used up to the last ink.
In addition, there are no problems such as ink evaporation, broken ink containers, etc., no ink spills while carrying, and no ink spills due to temperature changes.

It can be widely applied to printers using liquid ink, blocks, facsimiles, copiers, etc., and is suitable for small portable printers.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of this ink container. Figure 2 is a diagram showing the relationship between the diameter and length of a thin tube.
- Figure 5 shows another embodiment of the ink container of the present invention. -Applicant Shinshu Seiki Co., Ltd. Written on behalf of Suwa Seikosha, Patent Attorney, Uo Tsutomu Figure 1 Figure 2

Claims (1)

[Claims] In a printing device that places liquid ink on a recording medium, the liquid ink is stored in an internal ink container having at least a portion of a flexible wall, and an external ink container provided outside the flexible wall. An ink container characterized in that the external ink container suppresses evaporation of ink solvent evaporated from the flexible wall surface of the container.