Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2000-08-30
2002-04-30
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06378994
ABSTRACT:
BACKGROUND OP THE INVENTION
1. Field of the Invention
The present invention is directed to a liquid jet type recording head, a method for manufacturing the same, and a liquid jet type recording apparatus, and more specifically to a liquid jet type recording head used in a thermal type liquid ejector apparatus capable of continuously and stably jetting (printing) liquid at high speed, a method of manufacturing the same, and a liquid jet type recording apparatus using the same.
2. Description of the Related Art
Recently, the liquid jet recording apparatus has attracted a great deal of public attention because of its nature as a low-cost and high quality color recording apparatus. Exemplary liquid jet recording heads for use in the liquid jet recording apparatus includes, for example, a piezo-electric liquid jet recording head for jetting liquid through nozzles with the pressure generated by the mechanical distortion of pressure chamber by a piezo-electric element, and a thermal type liquid jet recording head for jetting liquid through nozzles with the pressure generated by evaporation of liquid by applying current to heating elements each of which is individually arranged in a separate channel.
There are some known ink jet printing heads in the Prior Art. Japanese Published Unexamined Patent Application No. Hei 9-226142 discloses the prevention of bubbles by providing an ink supplying channel having smaller cross-sectional area than the cross section of opening of the common ink chamber for an ink supplying channel to the common ink chamber communicating with the head orifice of the printing head. Japanese Published Unexamined Patent Application No. Hei 11-227208 discloses narrowing in the vertical direction the inner walls of head in the proximity of nozzles and liquid inlet within each orifice in the recording head to improve the ink supply. Japanese Published Unexamined Patent Application No. Hei 1-148560 discloses a method of creating an ink jet recording head by compiling a first substrate having ink channels and a common chamber formed by anisotropic etching on a surface side of silicon wafer, and a second substrate having heating elements and addressing electrodes formed on a surface side of silicon wafer. Japanese Published Unexamined Patent Application No. Hei 5-338177 discloses a printing head with a fitting arrangement of an ink manifold used as the common liquid chamber of recording head with an ink reservoir, having the back end wall of ink manifold formed as a sharp edge. Japanese Published Unexamined Patent Application No. Hei 5-338168 discloses a method of removing bubbles in a reservoir by forming an ink supplying lid of parallelogram to an ink reservoir of a printing head made of a silicon substrate. Japanese Published Unexamined Patent Application No. Hei 8-118666 discloses an ink jet recording head by forming an ink jet recording head chip by bonding plural silicon substrates, removing a part of one of silicon substrates of the head chip, and providing a common ink chamber having an ink supplying opening at the removed part. Japanese Published Unexamined Patent Application No. Hei 8-118653 discloses a method of improving the adhesiveness between silicon substrates in an inkjet printing head having two patterned silicon substrates bonded together by an intermediate thick film of a polymer by flattening by chemically or mechanically polishing the intermediate thick film layer of the ink jet printing head.
An example of the thermal type liquid jet recording head of the state of the art is disclosed in the Japanese Published Unexamined Patent Application No. Hei 9-226142. Now referring to
FIG. 20
, there is shown a perspective view of a liquid jet recording head and a liquid supplier incorporated in a liquid jet recorder of the Prior Art.
FIG. 21
depicts a cross-sectional view of the head shown in
FIG. 20
taken along with the line A—A.
A head chip
100
has plural channels
102
formed in parallel at a predetermined distance, and an ink outlet
104
is outwardly opened at an end of each channel
102
. The other end of each of plural channels
102
is communicated with a commonly shared ink chamber
106
. At the top of ink chamber
106
an opening
108
is formed for supplying liquid thereto. In each of channels
102
a heating element
110
is disposed, which generates heat to foam the liquid in the channel
102
, and the pressure generated by the foamed liquid forces the liquid to eject through the ink outlet
104
for recording.
The head chip
100
as has been described above may be formed by bonding a heating element substrate
114
with heating elements
110
mounted thereon and a channel substrate
116
having grooves formed for the channels
102
and the common ink chamber
106
, with the aid of a resin layer (not shown in the figure).
The heating element substrate
114
is affixed to a heat sink
118
for effective radiation of heat. On the heat sink
118
is formed a printed circuitry to transfer power and signals supplied from the liquid jet recorder through the bonding wires
120
to the heating element substrate
114
and to feed back signals generated by a variety of sensors incorporated in the heating element substrate
114
to the recorder.
On the head chip
100
, a liquid supplier member
122
is bonded. The liquid supplier member
122
includes liquid channels
124
for supplying liquid from a liquid reservoir (not shown) to the head chip
100
.
The liquid jet recording head thus formed will be supplied with liquid from the liquid reservoir through the separate channels
102
. In other words, the liquid supplied from the reservoir will flow through the liquid channels
124
of the liquid supplier member
122
, then through the liquid inlet
108
opened on the top of the channel substrate
116
of the head chip
100
to the common chamber
106
, in order to supply ultimately to each of the separate channels
102
.
In a liquid jet recording head as has been described above has a disadvantage that some bubbles will be intermixed with the liquid when introducing the liquid from the liquid reservoir to the liquid chamber
106
. The bubbles mixed therein along with the liquid tend to reside intensively in the area
126
(see
FIG. 21
) in the liquid chamber
106
where the liquid flow is slow. In case where bubbles reside in the chamber
106
for example, the bubbles will grow larger while repeatedly jetting the liquid so as to interfere the supply of liquid by blocking channels
102
, to ultimately cause the defects of recording. In the thermal type of liquid jet recording heads, the temperature of liquid will increase with the heating of heating element
110
. As the result of heating the air dissolved in the liquid, bubbles will be deposited in the common chamber
106
and enlarged to be likely to prevent smooth ejection of liquid drops therefrom. In this manner, heating may develop bubbles in the common chamber
106
as well as in the junction of the common chamber
106
with the liquid supplier member
122
, resulting in a problem of blocking by bubbles.
In order to purge bubbles residing in the common liquid chamber, it is common to aspirate through the nozzles
104
. When sucking bubbles through the nozzles
104
, an amount of liquid equivalent to the volume sucked will be supplied from the reservoir. Thus supplied liquid will spread along with the shape of the common liquid chamber
106
to be directed to the separate channels
102
. The liquid flow may force bubbles to advance toward the channels
102
to purge from the nozzles
104
. However, the bubbles residing at both ends of the chamber
106
, at the ends shown by the arrow in the direction of X, which are the primary cause of defects in the printing quality, are difficult to be completely removed because these bubbles are in the area of very slow flow of liquid.
In order to remove bubbles residing at both ends of the chamber
106
as has been described above, in the liquid jet recording heads of the Prior Art, dummy nozzles
126
have to be provided at both ends of the chamber
106
Funatsu Norikuni
Hamazaki Toshinobu
Hara Kohzo
Ikegami Koji
Kataoka Masaki
Barlow John
Fuji 'Xerox Co., Ltd.
Morgan & Lewis & Bockius, LLP
Stephens Juanita
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