Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1998-11-27
2001-07-03
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C347S094000
Reexamination Certificate
active
06254222
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a liquid jet recording apparatus which applies energy to liquid held in a liquid channel and spouts the liquid outside through a discharge orifice, and a method for fabricating the same.
FIG. 19
is a perspective view exemplarily showing a conventional liquid jet recording apparatus, and
FIG. 20
is across sectional view taken on line A in FIG.
19
. In those figures, reference numeral
1
is a flow channel substrate;
2
is an element substrate;
3
is a thick layer;
4
is a liquid inlet;
5
is a common liquid chamber;
6
is a by-pass channel;
7
is a liquid flow channel;
8
is a heating resistor element;
9
is a discharge orifice; and
10
is a stepped portion. The illustrated liquid jet recording apparatus is of the thermal type. In this type of the apparatus, the energy converting element for converting electric energy to thermal energy is the heating resistor element
8
. The liquid jet recording apparatus is disclosed in Japanese Patent Laid-Open Publication No. Hei 6-183002, for example. The energy converting means may be a piezoelectric element or the like.
The flow channel substrate
1
may be made of silicon, for example. Trenches to be used as a number of liquid flow channels
7
and a through-hole to be used as the common liquid chamber
5
are formed in the flow channel substrate
1
by an anisotropic etching method. One end opening of the through-hole serves as the liquid inlet
4
. The common liquid chamber
5
is formed in two steps to have the stepped portion
10
by anisotropic etching process. The element substrate
2
may also be made of silicon, for example. The heating resistor element
8
, which are associated with the liquid flow channel
7
, are formed on the element substrate
2
, and wires and drive circuits to supply electric energy to the heating resistor element
8
are further formed in the element substrate. The thick layer
3
made of polyimide, for example, is layered on those elements, wires and circuits on the element substrate. The thick layer
3
is removed of its regions for the by-pass channels
6
interconnecting the liquid flow channels
7
and the common liquid chamber
5
, which are formed in the flow channel substrate
1
, and the regions above the heating resistor element
8
. The thick layer
3
is required for forming the by-pass channels
6
, and serves as a passivating layer for protecting the wires and drive circuits formed in the surface of the element substrate
2
against liquid attack. The flow channel substrate
1
and the element substrate
2
, which are thus formed, are aligned in position with each other, and bonded together.
FIG. 21
is a cross sectional view showing a liquid jet recording apparatus equipped with a manifold. In the figure, reference numeral
11
is a manifold and
12
is an adhesive. After the liquid jet recording apparatus as shown in
FIG. 19
is manufactured, the manifold
11
is attached to the liquid jet recording apparatus in order to supply liquid from a liquid tank to the liquid inlet
4
of the apparatus. To attach the manifold, the adhesive
12
is applied to a portion around the liquid inlet
4
of the liquid jet recording apparatus, and the manifold
11
is bonded to the apparatus and liquid tightly sealed so as to prevent liquid from leaking outside.
In the general liquid jet recording apparatus, its purging and jetting performance depends largely on the length of the liquid flow channel if the cross sectional areas of the liquid flow channels
7
are equal to one another. Therefore, where the channel length becomes long, the flow channel resistance increases, and the amount of energy necessary for jetting the liquid becomes large or the amount of jetted liquid becomes small. This fact teaches that to design a high efficiency liquid jet recording apparatus, the length of the liquid flow channels
7
is reduced as short as possible.
If the channel length (length a in
FIG. 21
) of the liquid flow channel
7
is reduced, the common liquid chamber
5
is shifted to the discharge orifice
9
, and the distance from the surface having an array of discharge orifices
9
to the liquid inlet
4
, viz., the length b in
FIG. 21
, is reduced. As recalled, the portion around the liquid inlet
4
is coated with the adhesive
12
, and the manifold
11
is attached and bonded to the adhesive coated portion. Therefore, if the length b between the orifice-arrayed surface and the liquid inlet
4
is short, there is a chance that the adhesive
12
applied enters into the apparatus through the liquid inlet
4
. In this case, the adhesive obstructs the flow of liquid inside the apparatus, possibly causing a trouble of printing. As seen from the above facts, it is required that the channel length a of the liquid flow channel
7
is reduced as short as possible, but the length b between the orifice-arrayed surface and the liquid inlet
4
is selected to such an extent as to avoid the printing trouble. The liquid jet recording apparatus constructed as shown in
FIGS. 20 and 21
uses the stepped portion
10
to satisfy the above requirements, and to improve a production yield in the manufacturing of the liquid jet recording apparatus.
The liquid for recording is supplied through the liquid inlet
4
into the liquid jet recording apparatus, and flows in the direction of an arrow in FIG.
20
. The liquid flows from the liquid inlet
4
to the common liquid chamber
5
, passes through the by-pass channel
6
which is formed by removing the thick layer
3
, and reaches the liquid flow channel
7
.
In the instance mentioned above, the flow channel substrate
1
consists of a silicon substrate. A wet anisotropic etching method using a medicine liquid, e.g., KOH solution, is known for a method for fabricating trenches serving as the liquid flow channels
7
and the through-holes as the common liquid chambers
5
, as disclosed in U.S. Pat. No. 5,277,755.
FIGS. 22A
to
22
I are views showing a method for fabricating a liquid flow channel substrate of a conventional liquid jet recording apparatus. In the figure, reference numeral
31
designates a silicon substrate;
32
is an SiO
2
film; and
33
is an SiN film.
1)
FIG. 22A
A silicon substrate
31
to be used as the flow channel substrate
1
is arranged.
2)
FIG. 22B
A SiO
2
film
32
is formed on the silicon substrate
31
by thermal oxidation process.
3)
FIG. 22C
The SiO
2
film
32
is patterned to form the liquid flow channels
7
including the discharge orifices and the common liquid chamber
5
therein by a photolithography method and a dry etching method. The silicon substrate
31
used has a lattice face <
100
>.
4)
FIG. 22D
An SiN film
33
is formed over the resultant structure by a pressure-reduction CVD method.
5)
FIG. 22E
The SiN film
33
is patterned to form portions in which the common liquid chambers
5
are to be formed by photolithography and dry-etching process.
6)
FIG. 22F
With a mask of the SiN film
33
, the silicon substrate
31
is etched in a KOH solution. The etching process is continued till a through-hole is formed in the silicon substrate
31
, and the formed through-hole is used as the liquid inlet
4
.
7)
FIG. 22G
The SiN film
33
is removed.
8)
FIG. 22H
Using the SiO
2
film
32
as an etching mask, the silicon substrate
31
is etched in a KOH solution to form trenches to be the liquid flow channels
7
. In the etching process, the regions of the common liquid chambers
5
are etched to form the stepped portions
10
.
9)
FIG. 22I
Finally, the SiO
2
film
32
is selectively etched away in a hydrofluoric acid solution to complete the silicon substrate
31
to be used as the flow channel substrate
1
.
FIG. 23
is a plan view exemplarily showing a silicon substrate
31
to be used as the liquid flow channel substrate of the conventional liquid jet recording apparatus. Trenches serving as the liquid flow channels
7
and the through-holes to be used as the common liquid chambers
5
and the liquid inlet
4
, which correspond to a number of liquid flow cha
Fujii Masahiko
Fukugawa Atsushi
Murata Michiaki
Nayve Regan
Barlow John
Fuji 'Xerox Co., Ltd.
Oliff & Berridge PLC.
Stephen Juanita
LandOfFree
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