Incremental printing of symbolic information – Ink jet – Fluid or fluid source handling means
Reexamination Certificate
2002-09-10
2004-10-05
Vo, Anh T. N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Fluid or fluid source handling means
C347S087000
Reexamination Certificate
active
06799841
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet recording head, an ink jet recording apparatus using such ink jet recording head, and a method for manufacturing ink jet recording head.
2. Related Background Art
Of recording methods for a printer or the like, the ink jet recording method for forming characters, images, and the like on a recording medium by discharging ink for discharge ports (nozzles) has been widely adopted recent years, because it is non-impact recording method having a lesser amount of noises, while it can perform recording operation in high density at high speed.
A general ink jet recording apparatus is provided with an ink jet recording head; means for driving a carriage that mounts it; means for conveying a recording medium, and means for controlling them. The ink jet recording apparatus thus structured, that performs recording operation with the carriage, which is made to travel, is called serial type. On the other hand, the one that performs recording operation only by conveying a recording medium without the traveling of an ink jet head, is called line type. For the ink jet recording apparatus of line type, many numbers of nozzles are arranged in line all over the widthwise direction of a recording medium.
The ink jet recording head is provided with energy generating means for generating the discharge energy, which is given to ink in the nozzle in order to discharge ink droplets from the nozzle. As means for generating energy, there is the one that uses electromechanical converting element, such as piezoelectric element, the one that uses electrothermal converting element, such as heat generating resistive member, or the one that uses electromagnetic wave mechanical converting element or electromagnetic wave heat converting element, which converts electric waves of radio wave, laser, or the like into mechanical vibrations or heat, among some others. Of these methods, the type that discharges ink droplets by the utilization of thermal energy makes it possible to perform recording in high resolution, because nozzles can be arranged in high density. Particularly, the ink jet recording head that uses electrothermal converting element as the energy-generating element is easier to make it smaller than the head using electromechanical converting element. Further, such head has an advantage that it can fully utilize the IC technologies and micro machining techniques, the advancement and reliability of which have made a remarkable progress in the field of semiconductor manufacture in recent years, for easier assembling in high density at lower costs of manufacture.
As the ink supply method for an ink jet recording head, there is the one, which is of the so-called head-tank integrated type where the ink tank containing ink and the ink jet recording head are made one body; the one, which is of the so-called tube supply type where an ink tank and an ink jet recording head are connected by use of tube, or the one, which is of the so-called pit-in type where an ink tank and an ink jet recording head are provided separately, and the ink jet recording head moves to the position of the ink tank as required to connect them, and ink is supplied during such operation.
If the capacity of an ink tank is made larger in order to make the frequency of ink tank replacements smaller, the weight of the ink tank should increase. Therefore, in consideration of the increased weight given to the carriage of an ink jet recording apparatus of serial type then, it is not preferable to adopt the head-tank integrated one. Consequently, the ink jet recording apparatus of serial type that uses an ink tank of larger capacity adopts the tube-supply type or pit-in type more often. Of such types, the tube supply type, which makes it possible to perform a continuous recording for a long time, is adopted more often, because the pit-in type needs to suspend recording operation during the period of ink supply.
Hereunder, with reference to
FIG. 16
, the description will be made of the ink supply system of an ink jet recording apparatus of tube supply type.
The ink supply system shown in
FIG. 16
is provided with a main tank
1204
containing ink
1209
therein; a supply unit
1205
detachably installed in the main tank
1204
; and a recording head
1201
connected with the supply unit
1205
through a supply tube
1206
.
The supply unit
1205
has an ink chamber
1205
c
therein. The ink chamber
1205
c
is open to the air outside by way of an atmosphere communication port
1205
g
, while it is connected with the supply tube
1206
at the bottom thereof. Also, for the supply unit
1205
, there are fixed the ink supply needle
1205
a
and the air induction needle
1205
b
, the lower ends of which are positioned in the ink chamber
1205
c
, and the upper end of which are extruded from the upper face of the supply unit
1205
, respectively.
The lower end of the ink supply needle
1205
a
is positioned lower than the lower end of the air induction needle
1205
b.
The main tank
1204
has two connector portions formed by rubber plug or the like at the bottom thereof in order to close the inside of the main tank
1204
airtightly. Thus, the main tank is structured to be airtight individually. When the main tank
1204
is installed on the supply unit
1205
, the ink supply needle
1205
a
and the air induction needle
1205
b
penetrate the connector portions, respectively, so as to enter the inside the main tank
1204
. Now that the positions of the lower end of the ink supply needle
1205
a
and the air induction needle
1205
b
are defined as described above, ink in the main tank
1204
is supplied to the ink chamber
1205
c
through the ink supply needle
1205
a
, and the air outside is inducted into the main tank
1204
through the air induction needle
1205
b
so as to compensate for the reduction of pressure in the main tank
1204
. When ink is supplied into the ink chamber
1205
c
up to the position where the lower end of the air induction needle
1205
a
is immersed in ink, the ink supply from the main tank
1204
to the ink chamber
1205
c
is suspended.
The recording head
1201
is provided with a sub-tank portion
1201
b
in which a designated amount of ink is retained; an ink discharge portion
1201
g
where a plurality of nozzles is arranged for discharging ink; and a flow path that connects the sub-tank portion
1201
b
and ink discharge portion
1201
g
. For the ink discharge portion
1201
g
, nozzles are arranged with the opening surface thereof being placed downward, thus discharging ink downward. In each nozzle of the ink discharge portion
1201
g
, the aforesaid energy generating means is arranged. The sub-tank portion
1201
b
is positioned above the ink discharge portion
1201
g
, and the supply tube
1206
is connected with the sub-tank portion
1201
b
. Between the sub-tank portion
1201
b
and the flow path
1201
f
, a filter
1201
c
is installed with a fine mesh structure for preventing the nozzle from being clogged by minute foreign substances in ink that may otherwise enter the ink discharge portion
1201
g.
The area of the filter
1201
c
is defined to be a value to make the pressure loss by ink to be less than the allowable value. The higher the pressure loss of the filter
1201
c
, the finer is the mesh of the filter
1201
c
, and also, the more is the flow rate of ink passing the filter
1201
c
. On the contrary, the pressure loss is inversely proportional to the area of the filter
1201
c
. There is a tendency that the pressure loss becomes higher in a micro-dot recording head having many nozzles at higher-speed recording in recent years. Therefore, the area of the filter
1201
c
is made as large as possible in order to suppress the increase of pressure loss.
The nozzle is opened to the atmosphere, and also, the opening surface of the nozzle is placed downward. Therefore, in order to prevent ink leakage from the nozzle, it is necessary to keep the inside of the recording head
1201
to be negatively pressurized. On th
Goto Akira
Iijima Yasushi
Iri Junichiro
Kashino Toshio
Kigami Hiroyuki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Vo Anh T. N.
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