Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1997-09-26
2001-01-09
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06170934
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a nozzle plate production method and an apparatus for the same which produces a nozzle plate of an ink-jet head of an ink-jet printer.
Ink discharge characteristics of an ink-jet head of an ink-jet printer affect the quality of a printed image produced by the ink-jet head on a sheet of paper. The ink discharge characteristics are affected by the shape of a nozzle hole of a nozzle plate of the ink-jet head. When it is desired to produce a nozzle plate for an ink-jet head which provides a high quality printed image on the sheet of paper, the shape of the nozzle hole of the nozzle plate is an important factor to consider.
Generally, a large number of small nozzle holes with a given pitch are formed in the nozzle plate of the ink-jet head. It is a difficult task to accurately produce the nozzle plate so as to enable the ink-jet head to provide a high quality printed image, and the cost is likely to be increased. It is therefore desired to provide a nozzle plate production method, and an apparatus for the same, which is capable of easily and accurately producing the nozzle plate with a reduced cost.
(2) Description of the Related Art
Japanese Laid-Open Patent Application No. 7-60971 discloses a conventional nozzle plate of an ink-jet head.
FIG. 1
shows a nozzle plate
10
of a piezoelectric ink-jet head disclosed in the above-mentioned publication.
As shown in
FIG. 1
, the nozzle plate
10
includes a nozzle hole
11
. The nozzle hole
11
has a tapered portion
12
on the side of an upper end surface and a straight cylindrical portion
14
on the side of a lower end surface. The tapered portion
12
of the nozzle hole
11
is open to an ink chamber (not shown) of the ink-jet head. The cylindrical portion
14
extends from a bottom edge of the tapered portion
12
. The cylindrical portion
14
includes an ink discharge opening
13
from which ink is discharged. In the nozzle plate
10
of the above-mentioned publication, a ridge
15
is formed between the bottom edge of the tapered portion
12
and an upper edge of the cylindrical portion
14
.
FIGS. 2A
,
2
B and
2
C show basic processes of a nozzle plate production method disclosed in the above-mentioned publication.
The nozzle hole
11
of the nozzle plate
10
is formed through the nozzle plate production method of
FIGS. 2A
,
2
B and
2
C. The tapered portion
12
of the nozzle hole
11
is formed by performing a punching process of FIG.
2
A. When the punching process of
FIG. 2A
is performed, a nib
16
is produced on the bottom of the nozzle plate at the nozzle hole
11
. The nib
16
is removed from the nozzle plate by performing a grinding process of FIG.
2
B. The cylindrical portion
14
of the nozzle hole
11
is formed by performing a reaming process of FIG.
2
C. When the reaming process of
FIG. 2C
is performed, a burr is produced in the nozzle hole
11
. A grinding step is performed to remove the burr from the nozzle hole
11
. The nozzle plate
10
of
FIG. 1
is thus produced.
In the nozzle plate
10
of the above-mentioned publication, the ridge
15
has a sharp edge and a cross-sectional area of the nozzle hole
11
from the tapered portion
12
to the cylindrical portion
14
does not smoothly change. Therefore, the motion of the meniscus of the ink within the nozzle hole
11
when the ink is discharged from the nozzle hole
11
becomes noncontinuous and unstable, and the ink discharge characteristics of the ink-jet head are degraded.
It is difficult for the ink-jet head having the nozzle plate
10
of the above-mentioned publication to provide a high quality printed image because the ink discharge characteristics of the ink-jet head are low. Further, the nozzle plate production method of producing the nozzle plate
10
of the above-mentioned publication requires both the punching step and the reaming step be accurately performed to form the nozzle hole
11
, and it is difficult to reduce the cost for the production of the nozzle plate
10
.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved nozzle plate production method and apparatus in which the above-mentioned problems are eliminated.
Another object of the present invention is to provide a reduced-cost nozzle plate production method which can easily produce a nozzle plate of an ink-jet head in which nozzle holes are accurately formed in a prescribed configuration that provides good ink discharge characteristics for the ink-jet head.
Still another object of the present invention is to provide a reduced-cost nozzle plate production apparatus which can easily produce a nozzle plate of an ink-jet head in which nozzle holes are accurately formed in a prescribed configuration that provides good ink discharge characteristics for the ink-jet head.
A further object of the present invention is to provide a nozzle plate of an ink-jet head in which nozzle holes are accurately formed in a prescribed configuration enabling the ink-jet head to provide a high quality printed image on a sheet of paper.
The above-mentioned objects of the present invention are achieved by a nozzle plate production method which comprises the steps of: a nozzle hole punching step wherein a metallic sheet material is punched to form nozzle holes therein by using a press including punches, each of the punches comprising a tapered conical portion extending from a base portion of the punch, a straight cylindrical portion extending to a leading edge of the punch, and a rounded interconnecting portion, the rounded interconnecting portion smoothly interconnecting the conical portion and the cylindrical portion; a nib removal step wherein nibs produced on a bottom surface of the sheet material at the nozzle holes by the nozzle hole punching step are removed; a buffing step wherein a top surface and the bottom surface of the sheet material are buffed to provide a predetermined level of surface roughness; and a burr removal step wherein burrs produced on the top and bottom surfaces of the sheet material at the nozzle holes by the buffing step are removed.
The above-mentioned objects of the present invention are achieved by a nozzle plate production apparatus which comprises: a press which punches a metallic sheet material to form nozzle holes therein, the press having punches, each of the punches comprising a tapered conical portion extending from a base portion of the punch, a straight cylindrical portion extending to a leading edge of the punch, and a rounded interconnecting portion, the rounded interconnecting portion smoothly interconnecting the conical portion and the cylindrical portion; a grinding machine for removing nibs produced on a bottom surface of the sheet material at the nozzle holes by the punching of the press; a buffing machine for buffing a top surface and the bottom surface of the sheet material after the nib removal by the buffing machine to provide a predetermined level of surface roughness; and an ultrasonic cleaning machine for removing burrs produced on the top and bottom surfaces of the sheet material at the nozzle holes by the buffing of the buffing machine.
The above-mentioned objects of the present invention are achieved by a nozzle plate of an ink-jet head, the nozzle plate having a plurality of nozzle holes arranged in the nozzle plate, each of the nozzle holes comprising: a tapered conical surface which extends from a top opening of the nozzle hole; a straight cylindrical surface extending from a bottom opening of the nozzle hole; and a rounded interconnecting surface which smoothly interconnects the conical surface and the cylindrical surface.
In the nozzle plate production method and apparatus of the present invention, the nozzle holes of the nozzle plate, each having the conical surface, the interconnecting surface and the cylindrical surface, can be formed by the punching step, and it is possible to easily and accurately produce with a reduced cost the nozzle plate having a prescribed configuration. The punches of the press according to t
Fujisawa Takanobu
Kawarada Terukazu
Kawasaki Yoshiaki
Suzuki Masaharu
Tsukahara Tooru
Armstrong, Westerman Hattori, McLeland & Naughton
Barlow John
Brooke Michael S.
Fujitsu Limited
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