Ink cartridge with negative-pressure regulating mechanism

Details Ink cartridge with negative-pressure regulating mechanism Ink cartridge with negative-pressure regulating mechanism

2002-06-20

2004-07-13

Meier, Stephen D. (Department: 2853)

Incremental printing of symbolic information

Ink jet

Fluid or fluid source handling means

C347S086000, C347S089000

Reexamination Certificate

active

06761440

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The ink cartridge of the invention is installed with the regulating mechanism between the first and second ink chambers, and the regulating mechanism, activated with the variations of the inner pressure, is to connect the first and second ink chambers, enabling the second ink chamber to maintain negative pressure for stable replenishment of ink.
2. Description of the Prior Art
Based upon the history of invention regarding printers, printers on the market can be divided into three categories according to common usage: earlier dot-matrix printers, later ink-jet printers and laser printers. Nowadays ink-jet or laser printers have already constituted the mainstream on the market, with advantages and disadvantages shown for both types of printers. At first, ink-jet printers are less expensive than laser printers; secondly, as far as the printing quality is concerned, laser printers then provide better printing quality than that of ink-jet printers.
Even though ink-jet printers have the price advantage over laser printers, in terms of the printing quality, however, the ink-jet printers would lose the competitive edge against laser printers in applicable fields that require high printing quality. Generally speaking, ink in ink-jet printers diffuses, and because the printing material ink-jet printers use is of fluid, thus certain natural flaws existed in fluid during application seriously compromise the printing quality of ink-jet printers, e.g., the non-rigid body of the fluid, fluid's not flowing smoothly, bubbles existed in fluid and with the low viscosity coefficient of fluid, it is difficult to control the flowing direction.
The most primordial prior art for the ink cartridge of ink-jet printers is to fill ink directly into the ink cartridge; that is to say, there is only ink contained in the containing space of the ink cartridge without any other substances. Later on such technology almost totally exposed the foregoing drawback of the ink-jet printers, that is to say, the drawbacks caused by the uncontrollability of fluid were thoroughly manifested by the primordial ink cartridge technology. Even though later on new designs have been presented to try to improve on the foregoing drawbacks, the problem derived from the uncontrollability of fluid still exists. The invention is thus developed to solve such difficulty so as to the problem can be broken through. The prior arts in this field are to be introduced first:
1. Prior Art (1)
The most primitive prior art of the ink cartridge in ink-jet printers is to fill ink directly into the structural space of ink cartridges, as shown in FIG.
1
. What
FIG. 1
shows is a simple diagram of the ink cartridge, wherein N represents the ink-jet nozzle, which is a device where ink is spurted, and S
1
represents the space of the ink cartridge in which ink is filled, also the space where ink is replenished.
Though such prior art is not original at all, it is simply designed with lower production cost, yet such design fully exposes the drawback of the uncontrollability of fluids. Because the ink-jet nozzle is located underneath, thus an ink-feeding orifice underneath the ink cartridge (where ink is spurted) has to be designed; since the gravitational force leads liquid to flow downwards, ink in the ink cartridge could be led to leak downwards. Thus the only way to prevent such leaking is to depend on the surface tension of liquids. Only when the surface tension of the liquid at the ink-jet nozzle and the hydraulic pressure reach the equilibrium of force might the leaking of ink be prevented.
However, because the surface tension of liquids is not huge enough; therefore, if the surface tension is to be used for sustaining the liquid pressure of ink at the ink-jet nozzle, the vertical depth and diameter of the ink-spurting orifice, the viscosity coefficient and the surface tension of ink, and the weight and height level of the remaining ink are to be calculated and designed, so as to maximize the result of preventing leaking of ink through precise calculation to select all the parameters.
Yet with the surface tension of liquids being too insignificant that the impact thereof in the equation of the equilibrium of force is not significant either comparing to that from other elements, any slight variation of parameters shall compromise the equilibrium of force, thus causing the leaking of ink for printers due to the surface tension of liquid unable to sustain the liquid pressure. Under such circumstances, all elements possible of influencing the equilibrium of force need to be precisely designed and controlled during the uninterrupted use of ink. However, the elements capable of influencing the equilibrium of force are numerous and some of them are difficult to control, e.g., the variation of liquid pressure during uninterrupted use of ink, the impact of temperature, ink components and impurities in solution on the viscosity coefficient and the surface tension, also the impact of the air pressure inside the ink cartridge and the atmospheric pressure, all the elements that are not only difficult to control, but under the circumstances of the foregoing elements' impact force far larger than the surface tension of liquids on the equation of the equilibrium of force, any minute variation of an element is capable of compromising the equilibrium equation. Consequently, such field of precise liquid mechanical control costs too much and is difficult to achieve.
2. Prior Art (2)
Improvements on the prior art (1) achieved include installing water-absorbing material S
2
(e.g., sponge) in the structural space of the ink cartridge, as shown in FIG.
2
. Such improvement, in terms of the prior art (1), does correct the drawback of ink leaking, but also emerges following such improvement is that ink filled in the ink cartridge cannot be thoroughly used.
As shown in
FIG. 2
, when the ink cartridge is filled with sponge that has powerful water-absorbing ability, ink can be tightly absorbed in the ink cartridge, thus preventing ink from leaking or drooping, and alleviating the burden borne by the surface tension. Therefore, in the equation of the equilibrium of force, the absorbing ability of sponge in the ink cartridge is also to be counted, along with the surface tension of ink, as part of the force to prevent ink from leaking, and through calculation, the degree of the absorbing ability of sponge is larger than that of the surface tension of ink. Thus, the improvement of the Prior art (2) enables the equilibrium of force not to be easily undermined by factors in the prior art (1) that are capable of affecting the equilibrium and hard to control. Under the circumstance, the absorbing force provided by sponge keeps ink in the ink cartridge from leaking easily, and thus ridding of the drawback of ink leaking of the printer, a design that is the most important feature of such technology.
Nevertheless, since the containing space of the ink cartridge is limited, when sponge is filled therein, the quantity of ink that can be filled in is to be decreased. Furthermore, because the water-absorbing material, like sponge, has the absorbing force, when ink is about to be used up, a certain portion of ink that is unable to overcome the absorbing force of sponge, is to be kept in the ink cartridge, thus causing such portion of ink to be wasted. For example, a space in the ink cartridge that is originally designed to fill in 40 g of ink is to be partially occupied with sponge, thus only 30 g of ink can be filled in, whereas for such 30 g of ink, about 6 g to 7 g of ink is to be absorbed by sponge and remained in the ink cartridge without being able to be used. As a result, by design 40 g of ink is supposed to be available for use, yet the user can only use about 23 g to 24 g of ink eventually, a drawback that is a waste in terms of the use of both space and ink.
Moreover, another serious flaw of such technology is the unsmooth flow of ink. Because sponge possesses both characters of the water-absorbing ability and th

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