Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
1999-12-22
2003-06-10
Nghiem, Michael (Department: 2863)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06575567
ABSTRACT:
FIELD OF THE INVENTION AND RELATED ART
The present invention relates to a liquid delivery system which uses negative pressure to deliver liquid out of a liquid container, more specifically, a liquid delivery system for delivering liquid to a liquid jet recording apparatus which records images on recording medium. It also relates to a replaceable liquid container for the liquid delivery system, and a head cartridge.
There are a number of liquid delivery methods which use negative pressure to deliver liquid out of a liquid container. In the field of an ink jet recording apparatus, for example, an ink container which provides an ink jet recording head with negative pressure has been proposed, and has been put to practical use, in the form of an ink jet cartridge which integrally comprises a recording head and a negative pressure providing ink container. There are a number of ink jet cartridges, which can be classified into two groups: those which cannot be separated into a recording head and an ink container (ink storing portion), and those which can be separated into a recording means and an ink storing portion. In the case of the latter group, they can be individually separated from a recording apparatus, but remain united when they are used for recording.
There are various methods for generating negative pressure in the aforementioned liquid delivery system, and the simplest one is to use the capillary force of porous material. An ink container used for such a method comprises a shell, and a piece of porous material such as sponge for storing ink. The shell is provided with an air vent through which the atmospheric air is taken into the ink storing portion of the ink container so that ink is smoothly delivered during a printing operation. It is preferable that the porous material is compressed into the shell to fill virtually the entirety of the internal space of the ink container.
However, the usage of porous material as ink holding material creates some problems. One such problem is that the filling of an ink container with porous material reduces the ratio of the amount of ink storable in an ink container to the internal space of the ink container. In order to solve this problem, the applicants of the present invention proposed an ink container, which is disclosed in EP0580433 (official gazette). According to this proposal, an ink container is provided with a virtually sealed ink reservoir, and a negative pressure holding chamber in which a negative pressure generating member is held. The internal spaces of the ink reservoir and negative pressure generating member holding chamber are connected through a passage, and the negative pressure generating member holding chamber is open to the atmosphere. The applicants of the present invention also disclosed another invention disclosed in EP081531 (official gazette). According to this invention, an ink reservoir is made replaceable.
In the case of the aforementioned ink container, the ink within the ink reservoir is delivered from the ink reservoir to the negative pressure generating member holding chamber, as the atmospheric air displaces the ink within the ink reservoir in response to the ink delivery from the ink reservoir. Thus, the aforementioned ink reservoir has merit in that the negative pressure is kept virtually constant while the ink is delivered during this gas-liquid exchange stage.
The applicants of the present invention also proposed a liquid storing container, which is disclosed in EP0738605 (official gazette). According to this proposal, a liquid storing container comprises an outer shell in the form of a virtually polygonal prism, and a liquid storing portion placed in the outer shell. This proposal is characterized in that the liquid storing portion is similar in shape to the outer shell, the outward surface of each of its walls being in contact with, or closely following, the inward surface of the correspondent wall of the outer shell; that the liquid storing portion is enabled to deform in response to the outward delivery of the liquid stored in the liquid storing portion; and that the thickness of the walls of the liquid storing portion is greater at its corner portions than at the center portions of the walls. The liquid storing portion of this liquid storing container contracts by a proper amount in response to the ink delivery therefrom (liquid in the ink storing portion is not displaced by gas), so that liquid can be delivered while maintaining a proper amount of negative pressure. Therefore, unlike a conventional ink storing member, which is in the form of a pouch, this liquid storing container does not have any restriction regarding its positioning. Thus, it can be mounted on a carriage. Further, ink is directly stored in the storing portion, which makes this invention superior also in terms of ink storage efficiency.
It should be noted here that, in the case of an ink container of such a type that comprises a negative pressure generating member holding chamber such as the one described above, and a matching ink reservoir which is placed adjacent to the negative pressure generating member holding chamber, and is provided with a predetermined amount of storage space, gas is introduced into the ink reservoir to displace the ink (gas-liquid exchange occurs) as the ink within the ink reservoir is delivered into the negative pressure generating member holding chamber.
In other words, as the ink in the ink reservoir is delivered to the negative pressure generating member holding chamber, the atmospheric air is introduced into the ink reservoir in response to the ink delivery, by an amount equal to the amount of the delivered ink. Therefore, the ink reservoir is occupied with both the introduced outside air, and ink. If the air in the ink reservoir is expanded by the changes (for example, daily temperature fluctuation) in the ambience in which the printer is used, the ink within the ink reservoir is sometimes forced into the negative pressure generating member holding chamber side by the expansion. For this reason, in the past, the ratio of the amount by which the ink is moved, to the air expansion, in various environments in which the recording apparatus is used, had to be taken into consideration to provide the negative pressure generating member with the maximum amount of buffering space, in terms of practical use. As a result, it was very difficult to provide an ink reservoir with an internal volume greater than a certain size.
In order to solve the above described problems, the inventors of the present invention analyzed in detail an ink container of such a type that comprised a negative pressure generating member holding chamber, and an ink reservoir matching the negative pressure generating member holding chamber, in the state in which the ink reservoir contained air. As a result, it was discovered that the delivery of the ink in the ink reservoir to the negative pressure generating member holding chamber is directly linked to the introduction of the outside air, and therefore, in order to solve the above described problem, the amount by which ink moves from the ink reservoir to the negative pressure generating member should be regulated.
Further analysis led the inventors to an idea that, although it is impossible to prevent the air present in the ink reservoir from expanding, it is possible to contain the effect of the expansion of the air in the ink reservoir, within the ink reservoir, which is contrary to the conventional concept.
SUMMARY OF THE INVENTION
The present invention was made as the result of further study of the aforementioned discovery and knowledge carried out by the inventors of the present invention.
An essential thought kept in the minds of the inventors of the present invention was in order to reliably deliver ink even immediately after the exchange of the ink reservoir, a structure for enhancing the introduction of atmospheric air, which effectively functions without being clogged by the adhesion of solidified ink or the like, should be provided.
The primary object of the present
Ishinaga Hiroyuki
Matsumoto Hidehisa
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