Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2002-10-03
2004-08-10
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06773099
ABSTRACT:
This application is based on Japanese Patent Application Nos. 2001-310648, 2001-310647 and 2001-310646 filed Oct. 5, 2001, and Nos. 2001-398215 and 2001-398214 filed Dec. 27, 2001, the content of which are incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid container, a liquid supplying apparatus, and a recording apparatus for supplying a liquid such as ink to a pen or recording head as a recording section, for example, in an efficient and stable manner, and to an ink jet cartridge.
2. Description of the Related Art
Ink jet recording apparatuses that form an image on a recording medium by applying ink that is a liquid to the recording medium using a liquid consuming or using apparatus such as an ink jet recording head include apparatus that form an image by ejecting ink while moving a recording head relative to a recording medium and apparatus that form an image by ejecting ink while moving a recording medium relative to a fixed recording head conversely.
Methods of supplying ink to a recording head used in such an ink jet recording apparatus include a method referred to as on-carriage method in which an ink tank is integrally or separably mounted to a recording head that is carried by a carriage to be moved back and forth (main scanning) and in which ink is directly supplied from the ink tank to the recording head. There is another method referred to as tube supply method in which an ink tank is fixed in a region of a recording apparatus other than a carriage as a body separate from a recording head carried by the carriage and in which ink is supplied by coupling the ink tank and the recording head through a flexible tube. The method includes a configuration in which a second ink tank to serve as an intermediate tank (sub-tank) between an ink tank (main tank) and a recording head is mounted on the recording head or a carriage and in which ink is directly supplied from the second ink tank to the recording head.
According to those methods, an ink tank to supply ink to a recording head directly is provided with a mechanism for generating an adequate negative pressure in a range in which the negative pressure is in equilibrium with a pressure in the recording head to hold meniscuses formed at an ink ejecting section thereof to prevent the ink from leaking from the ink ejecting section satisfactorily and in which an ink ejecting operation of the recording head can be performed.
In a negative pressure generating mechanism of this type, a porous member such as a sponge that is impregnated with ink to be held thereby is contained in an ink tank, and an adequate negative pressure is generated by an ink holding capacity of the same.
In another mechanism, a bag-shaped member formed from a material such as rubber having an elastic force and generating a tension in the direction of increasing the volume thereof is charged with ink as it is, and the tension generated by the bag-shaped member exerts a negative pressure to the in therein.
In still another mechanism, a bag-shaped member is formed using a flexible film, and a spring for urging the film in the direction of increasing the volume of the bag-shaped member is bonded to the interior or exterior of the same to generate a negative pressure.
In any of the above mechanisms, however, the negative pressure tends to increase as the amount of ink in the ink tank decreases, and it becomes impossible to supply ink to a recording head stably when the level of the negative pressure exceeds a predetermined value. This results in a problem in that the ink tank becomes unusable before the ink is completely used up.
For example, there is Japanese Patent Application Publication No. 3-024900 (1991) which discloses a structure of an ink tank of a type which is constituted by a flexible enclosed bag-shaped member that directly contains ink therein and that can be deformed according to the amount of contained ink and in which a spring member is provided in the bag-shaped member. Since the negative pressure is basically determined such that the spring force and a force resulting from the negative pressure (or a difference between the atmospheric pressure and the negative pressure) are balanced with each other, the negative pressure in the bag-shaped member increases as the deformation of the spring proceeds with the deformation of the bag-shaped member as a result of ink consumption. This may result in a problem in that the negative pressure increases beyond a proper range in which an ink ejecting operation of the recording head can be performed to prevent the formation adequate meniscuses at the ink ejecting section of the recording head or in that the ink can not be satisfactorily supplied to the recording head. This also disallows the ink to be used completely.
Some ink tanks have a configuration in which ink is contained in a bag-shaped member, and the material and shape of which are appropriately selected to generate a negative pressure by the bag-shaped member itself and which becomes flat with no space left therein when the ink is completely used up, but there are limitations on the shape of such a bag-shaped member. Therefore, when such an ink tank is configured to be contained in a box-like housing, the configuration of the bag-shaped member does not fit the interior of the housing completely even when it is charged with ink, and the volumetric efficiency of the ink tank is low with respect to the entire space available therein. Such a bag-shaped member also has a problem in that its performance of supplying ink to a recording head can be reduced and in that it can make an ink ejecting operation of a recording head unstable when ink is nearly used up because of a high negative pressure.
Several mechanisms have been proposed as follows to prevent magnitude of a negative pressure being too much greater than the predetermined level.
For example, Japanese Patent Application Laid-open No. 7-125240 (1995) and Japanese Patent Application Laid-open No. 7-125241 (1995) have disclosed mechanisms in which a hydrophobic film and a tubular vent port are provided in a tank, and a spherical body is disposed in the tube to introduce air into the tank when a negative pressure therein increases. That is, those publications have disclosed mechanisms which have a tubular vent port (boss) that establishes communication between the outside and inside of a container and in which spherical body having an outer diameter smaller than an inner diameter of the boss is attached to a plurality of projecting ribs provided on an inner wall of the boss to form a substantially annular orifice with the spherical body and the boss. The size of such an orifice is chosen such that a small amount of ink is kept in the orifice as a liquid seal because of the capillarity of ink. The orifice is configured such that a negative pressure in the container overcomes the capillarity of ink to disable the liquid seal when it nearly reaches the limit of an operating range of the recording head.
Japanese Patent Application Laid-open No. 6-183023 (1994) has disclosed a mechanism in which a plate-like member having a hole and a plate having a protrusion are provided in a face-to-face relationship in an ink bag constituted by a flexible sheet with a spring member disposed between the plates and in which the protrusion enters the hole when an internal negative pressure exceeds a predetermined value to separate the plate having the hole and the flexible sheet from each other, thereby introducing air in the tank. In this mechanism, the plate having the hole and the flexible sheet come into tight contact with each other after air is introduced, and leakage of ink is prevented by an ability for holding ink meniscuses or a liquid seal formed between those elements.
However, those methods require a plurality of parts in a region where air is introduced, and the structure of such a region has therefore become complicated.
When a pressure in a container T having a certain amount of air introduced therein becomes extremely high
Inoue Ryoji
Ishinaga Hiroyuki
Kuwabara Nobuyuki
Ogura Hideki
Ohashi Tetsuya
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Vo Anh T. N.
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