Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2002-02-07
2004-11-30
Brooke, Michael S. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
Reexamination Certificate
active
06824258
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a liquid container detachably mounted on an ink jet recording apparatus, and a recording apparatus utilizing such liquid container.
2. Related Background Art
The liquid container mounted on an ink jet recording apparatus, for executing recording by discharging liquid droplet onto a recording sheet, is generally classified into two types, namely a type detachably mounted in the recording apparatus but used in a fixed state, and a type used in a moving state together with a recording head in the transversal direction of the recording sheet in a recording apparatus of so-called serial scan type. The serial scanning means a system in which the recording head is moved in a direction crossing the conveying direction of the recording sheet.
In the so-called on-demand ink jet recording which is a currently prevailing system among various ink jet recording methods and forms a recorded image by discharging a liquid droplet onto a sheet (such as paper) in response to a recording signal, it is essential to maintain a somewhat negative pressure relative to the atmospheric pressure at the nozzle end (also called orifice) of the recording head, in order to discharge the liquid droplet always in a stable manner in response to the recording signal.
The liquid container of the latter type moving together with the recording head of serial scan type is also called an on-carriage tank and is employed widely, because the recording head and the liquid container, containing liquid to be supplied to the recording head, are positioned close whereby the ink supply path can be made shorter and the recording apparatus can be realized compact.
Also as a configuration capable of retaining the liquid therein and supplying the liquid to the exterior, there is commonly used a liquid container utilizing a foamed member such as urethane foam or an entangled fibrous member such as of polypropylene fibers as a capillary force generating member.
However, in case of the latter on-carriage tank, the liquid container mountable together with the recording head on the carriage has a certain limitation in size. More specifically, if a large liquid container is employed in order to reduce the frequency of replacement of the liquid container, there is required an enormous space in order not to hinder the movement of such liquid container, so that the recording apparatus itself becomes large. This drawback becomes more serious in a 4-color or 6-color recording apparatus.
In consideration of such fact, there is increasingly employed the recording apparatus having the ink tank in detachable manner in a fixed position in the apparatus instead of mounting the ink tank on the carriage supporting the recording head, particularly in case of a wide format printer utilizing a very wide recording sheet (liquid supply amount per sheet being accordingly large) or a network printer which is a recording apparatus of a very high working rate. The liquid container in such recording apparatus corresponds to the former and, particularly in case of the recording apparatus of serial scan type, is called an out-carriage tank or an off-carriage tank because the liquid container is fixed in the recording apparatus independently from the movable carriage.
However, such conventional liquid containers have been associated with drawbacks to resolve. Such issues will be explained in the following by the examples of the prior art.
FIG. 22
shows a liquid container
101
having two fluid connection ports
102
,
103
with the exterior, approximately at the center of an upper face
101
a
of the liquid container. The connection port
102
is exclusively for deriving liquid
105
from the upper face
101
a
through an internal supply pipe
104
so provided as to reach the bottom
101
b
, in order to securely extract the liquid while the liquid level is lowered by the liquid extraction, until the container becomes almost empty. The other connection port
103
is exclusively for opening to the external air and is so constructed as to directly communicate with the air present above the liquid level in the container.
In such liquid container
101
, the liquid level open to the air therefore varies from the upper part
101
a
of the container to the bottom
101
b
thereof. Consequently such liquid container, if directly connected to the ink jet recording head, shows a wide range in the supplied negative pressure, so that the liquid container cannot be made very large (particularly in the direction of gravity).
Also, if there is employed a supply system which once transfers the liquid from the liquid container to the exterior and stabilizes the negative pressure by a relaying tank, there will be required additional components such as a transfer pump and a relaying tank. Furthermore, the connection pipe
103
open to the air is not in contact with the contained liquid
105
in the liquid container and cannot therefore be used as a conductive electrode for detecting the remaining ink amount in combination with the other connection pipe
102
, so that there is required another method such as forming a hole in the container bottom
101
b
and inserting an electrode for detecting the remaining amount of the contained liquid. Such method inevitably leads to additional drawbacks of an increase in the cost and possible liquid leakage.
FIG. 23
shows a liquid container
201
of lateral mounting type, in which a connection port
202
for liquid extraction is formed on a lateral face close to the bottom
201
b
of the liquid container
201
and a connection port for opening to the air is formed on a lateral face close to the upper part
201
a
of the liquid container
201
. Such liquid container does not require the internal supply pipe but other drawbacks are same as those of the liquid container shown in FIG.
22
.
In the ink jet recording technology, there are being required clarity, water resistance, light fastness etc. of the print, and it is proposed to use pigment as the coloring agent of the ink as one of the methods for meeting such requirements. In the pigment-based ink, the pigment is dispersed in ink solvent, and the pigment, having a specific gravity larger than that of the solvent, tends to precipitate after a prolonged standing. For this reason, the pigment concentration becomes different between the upper part and the lower part of the ink contained in the ink tank, thereby generating fluctuation in the print density.
An ink tank disclosed in the Japanese Patent Applications Laid-open Nos. 9-164698, 11-348308 etc. is provided, on the bottom of the container, with a connection port which is positioned close to a lateral wall of the container, but such arrangement of the connection port is determined by the position of an ink supplying pump and does not provide any solution to the pigment precipitation in case pigment is used in the ink.
Also an ink tank disclosed in the Japanese Patent No. 2,929,804 is provided at the bottom thereof with a connection port into which a connection needle communicating with the air and a connection needle for liquid derivation are to be inserted and which is positioned at the center of the tank. Such container configuration is not suitable for a replaceable container since a strong force is required at the connecting operation and the inserting positions of the needles cannot be fixed at each insertion. However there are not taught the issue of pigment precipitation and the position for ink extraction.
Also an ink tank disclosed in the Japanese Patent Application Laid-open No. 10-337879 and the U.S. Pat. No. 6,074,042 has a complex configuration in which an ink chamber is composed of a flexible bag that can be flattened in order to use up the ink contained therein and such flexible bag is pressurized in a casing. Consequently the ink containing space is generally small within the ink tank casing and such configuration is difficult to use for the purpose of providing a tank of a high containing efficiency within a limited space.
Also an ink
Hatasa Nobuyuki
Kono Takeshi
Koshikawa Hiroshi
Nanjo Tatsuo
Shimizu Eiichiro
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
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