Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-11-07
2003-07-15
Nguyen, Thinh (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06592209
ABSTRACT:
RELATED APPLICATION DATA
The present application claims priority to Japanese Application(s) No(s). P2000-344233 filed Nov. 7, 2000, which application(s) is/are incorporated herein by reference to the extent permitted by law.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printer, a printer head, and a method of producing the printer head. In particular, the present invention is applicable to a printer which makes use of a process of which causes ink droplets to fly out as a result of heating by a heater. The present invention makes it possible to, by preventing a thickness-direction stepped portion from being formed at least at a partition of an ink chamber as a result of disposing a wiring pattern below the partition of the ink chamber, bring an orifice plate sufficiently into close contact with what it is to be bonded to and bond it thereto.
2. Description of the Related Art
In recent years, in the field of image processing and the like, there has been an increasing need for color hard copies. To respond to this need, there has been conventionally proposed a sublimation thermal transfer process, a fusion thermal transfer process, an inkjet process, an electrophotographic process, a thermally processed silver process, and the like.
In the inkjet process, a dot is formed by causing small drops of recording liquid (ink) to fly out from a nozzle of a recording head and causing them to adhere to what is to be subjected to a recording operation. This makes it possible to output a high-quality image using a simple structure. The inkjet process is classified into, for example, an electrostatic attraction process, a continuous vibration generation process (piezo process), and a thermal process, depending on the method used to cause the ink to fly out.
In the thermal process, air bubbles are produced by heating localized portions of the ink in order to push out the ink from a discharge opening by the air bubbles, thereby causing the ink to fly out to what is to be subjected to printing. This makes it possible to print a color image using a simple structure.
A printer which operates by this thermal process is constructed using what is called a printer head, which has mounted therein a heating element which heats ink, a drive circuit based on a logic integrated circuit which drives the heating element, and other component parts.
FIG. 8
is a sectional view partly showing a thermal head of the prior art. In forming a printer head
1
, an isolation area
3
(LOGOS: local oxidation of silicon) which isolates transistors is formed on a P-type silicon substrate
2
, and, for example, a gate oxide film is forced at a transistor formation area remaining between portions of the isolation area
3
, thereby forming MOS (metal oxide semiconductor) switching transistors
4
and MOS transistors
5
and
6
forming a drive circuit.
Next, in forming the printer head
1
, after placing, for example, an insulating film, a contact hole is formed in order to form a first-layer wiring pattern
7
. By the first-layer wiring pattern
7
, the MOS transistors
5
and
6
, forming the drive circuit, are connected to each other, thereby forming a logic integrated circuit.
Next, in forming the printer head
1
, after, for example, the insulating film has been placed, sputtering is carried out in order to deposit heating element materials, such as tantalum, tantalum aluminum, or titanium nitride, in order to form resistance films in localized portions. By the resistance films, heating elements
8
which heat ink are formed.
Next, in forming the printer head
1
, a contact hole is formed to form a second-layer wiring pattern
9
. By the second-layer wiring pattern
9
, a connection portion between the switching transistors
4
and the heating elements
8
, a connection portion between the heating elements
8
and a power supply, a ground line, and the like, are formed.
Next, in forming the printer head
1
, an insulating material, such as SiO
2
or SiN, is deposited in order to form a protective layer
10
, after which a Ta film is formed on localized portions of the heating elements
8
. By the Ta film, a cavitation resistance layer
11
is formed. Next, a dry film
13
and an orifice plate
14
are successively placed upon each other. Here, the dry film
13
is formed of, for example, carbon resin. After placing it by contact bonding, portions thereof situated in correspondence with an ink chamber and an ink path are removed, after which a hardening operation is carried out. On the other hand, the orifice plate
14
is formed of a plate-shaped material which is processed into a predetermined shape so that a nozzle
15
, which is a very small ink discharge opening, is formed above the heating elements
8
. The orifice plate
14
is supported on the top portion of the dry film
13
as a result of adhering it thereto. When the above-described operations are carried out, the nozzle
15
, an ink chamber
16
, a path for guiding ink into the ink chamber
16
, etc., are formed at the printer head
1
.
In the printer head
1
, the ink is guided to the ink chamber
16
, and, by a switching operation of the switching transistors
4
, the heating elements
8
generate heat in order to heat localized portions of the ink. By the heating, core air bubbles are produced at side surfaces of the heating elements
8
of the ink chamber
16
. These core air bubbles combine to form film air bubbles. When pressure is increased by the air bubbles, the ink is pushed out from the nozzle
15
and flies out to what is to be subjected to printing. As a result, in a printer using the printing head
1
, intermittent heating by the heating elements
8
causes the ink to successively adhere to what is to be subjected to printing, so that a desired image is formed.
Further, in the printer head
1
, the switching transistors
4
, which drive the heating elements
8
are controlled by the same logic integrated circuit formed by the MOS transistors
5
and
6
. Therefore, the heating elements
7
are disposed very closely together, thereby making it possible to reliably drive them by their corresponding switching transistors
5
,
6
.
In other words, in order to obtain a high-quality printed result, the heating elements
8
need to be disposed very close to each other. More specifically, in order to obtain, for example, a 600 DPI printed result, the heating elements
8
need to be disposed at intervals of 42,333 &mgr;m. It is extremely difficult to dispose individual drive elements at the heating elements
8
disposed very close to each other. Therefore, in the printer head
1
, for example, switching transistors are formed on the semiconductor substrate and are connected to the corresponding heating elements
8
by an integrated circuit technology. Then, by the drive circuits similarly formed on the semiconductor substrate, the corresponding switching transistors are driven in order to make it possible to simply and reliably drive each of the heating elements
8
.
However, the printer head
1
having such a structure has a problem in that it is difficult to bring the orifice plate
14
sufficiently into close contact with the dry film
13
and to bond it thereto.
More specifically, in a commonly used semiconductor integrated circuit, the first-layer wiring pattern
7
is formed with the minimum thickness required, and the second-layer wiring pattern
9
, which forms a power supply line and a ground line, is made thick in order to obtain a desired current capacity.
In contrast to this, in the printer head
1
, the situation is reversed with respect to the case of the commonly used semiconductor integrated circuit, so that the first-layer wiring pattern
7
is made thick, whereas the second-layer wiring pattern
9
is made thin, in order to obtain good covering property at the silicon nitride film forming the ink protective layer
10
and the tantalum cavitation resistance layer
11
, which are formed above the heating elements
8
.
In the printer heat
1
, by virtue of such a structure, the second-layer wi
Kohno Minoru
Miyamoto Takaaki
Tanikawa Toru
Nguyen Thinh
Sonnenschein Nath & Rosenthal
Sony Corporation
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