Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-12-09
2002-03-26
Le, N. (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06361149
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet head which discharges ink through a nozzle hole onto a recording sheet by imparting a force to the contained ink within the ink jet head. The ink jet head of the present invention is suitably applicable to various image forming apparatuses including printers, facsimiles and copiers.
2. Description of the Related Art
Japanese Laid-Open Patent Application No. 7-125196 discloses a conventional ink jet head.
FIG. 5A
is a cross-sectional side view of the conventional ink jet head, and
FIG. 5B
is a cross-sectional view of the conventional ink jet head taken along a line B—B of FIG.
5
A.
As shown in FIG.
5
A and
FIG. 5B
, the conventional ink jet head is constructed by joining together a first substrate
1
, a second substrate
2
and a third substrate
3
. These substrates
1
,
2
and
3
are joined together so that a nozzle hole
4
, an ink chamber
6
, an orifice
7
and an ink cavity
8
are provided therein.
The first substrate
1
includes the ink chamber
6
and an oscillation plate
5
integrally formed with the first substrate
1
. The oscillation plate
5
is located beneath the ink chamber
6
. The second substrate
2
includes an individual counter electrode
9
which is disposed on the second substrate
2
and faces the oscillation plate
5
through an internal space or gap “G” between the oscillation plate
5
of the first substrate
1
and the counter electrode
9
of the second substrate
2
. A lead of the counter electrode
9
on a mounted surface “I” and a common electrode (not shown) extending from the oscillation plate
5
on a mounted surface “II” are electrically connected to a driver circuit
11
. A driving voltage between the individual counter electrode
9
and the common electrode is supplied by the driver circuit
11
.
Hereinafter, the first substrate
1
is referred to as the ink-chamber substrate
1
, and the second substrate
2
is referred to as the counter-electrode substrate
2
.
In the conventional ink jet head, when the driving voltage supply is turned on, an electrostatic force is created so as to downwardly pull the oscillation plate
5
toward the individual counter electrode
9
. When the supplying of the driving voltage is turned off, the oscillation plate
5
is upwardly deflected so as to impart a force to and stress the ink within the ink chamber
6
such that the ink is discharged from the nozzle hole
4
onto a recording sheet
12
.
As shown in FIG.
5
A and
FIG. 5B
, in the structure of the above-mentioned ink jet head, the leads of the counter electrodes
9
are disposed on the mounted surface I, and the common electrode extending from the oscillation plate
5
is disposed on the mounted surface II. The mounted surface I of the leads of the counter electrodes
9
and the mounted surface II of the common electrode routed from the oscillation plate
5
have different heights. A mounting process for mounting the ink-chamber substrate
1
on the counter-electrode substrate
2
, and a mounting process for mounting the third substrate
3
on the ink-chamber substrate
1
must be separately performed, and these processes are very complicated and expensive because the leads of the counter electrodes
9
and the common electrode are mounted on the mounted surfaces I and II with different heights.
Further, it is necessary to route the leads of the counter electrodes
9
to the connection points on the mounted surface “I”, as well as to route the common electrodes from the oscillation plates
5
to the connection points on the mounted surface “II”, in order to establish both the electrical connection between the counter electrodes
9
and the driver circuit
11
and the electrical connection between the common electrodes and the driver circuit
11
. This conventional ink jet head has connection points provided on the mounted surfaces “I” and “II” with different heights, and requires the relatively-large ink-chamber substrate
1
and the relatively-large counter-electrode substrate
2
. Accordingly, it is difficult for such a conventional ink jet head to achieve a high-density packaging of the counter electrodes and the oscillation plates in small-size substrates, as well as simple, inexpensive assembly processes.
Japanese Laid-Open Patent Application No. 5-169660 discloses another conventional ink jet head.
FIG. 6
is a cross-sectional view of this conventional ink jet head.
As shown in
FIG. 6
, the conventional ink jet head includes a supporting board
21
, a heater board
23
and a flexible wiring board
25
. The heater board
23
is provided on the supporting board
21
, and contains an energy-generating element which produces energy used to impart a force to and stress the ink within the conventional ink jet head in accordance with a print signal. When the energy is created by the energy-generating element of the heater board
23
, the ink is discharged from a nozzle hole
22
onto a recording sheet.
In the conventional ink jet head of
FIG. 6
, the flexible wiring board
25
is provided on the supporting board
21
, and the flexible wiring board
25
is electrically connected to the heater board
23
through a wire bonding or a tape automated bonding (TAB). A plurality of connection pads
24
are formed on the wiring board
25
, and the wiring board
25
is connected through the connection pads
24
to a main part of a printing device. The main part of the printing device supplies the print signal to the wiring board
25
via the connection pads
24
, and the wiring board
25
transfers the print signal to the heater board
23
via the bonded wire.
As shown in
FIG. 6
, in the structure of the above-mentioned conventional ink jet head, the flexible wiring board
25
must be bent at the end of the supporting board
21
so as to extend from the top surface of the supporting board
21
to the bottom surface thereof. The connection pads
24
are provided on the bottom surface of the wiring board
25
, and the top surface of the wiring board
25
is connected to the heater board
23
by the bonded wire or the TAB.
The conventional ink jet head shown in
FIG. 6
must be produced using the relatively-large supporting board
21
, and the supporting board
21
must have an adequately large thickness for attaching the flexible wiring board
25
thereto. It is difficult that the conventional ink jet head of the above publication be provided with a smaller supporting board
21
. Further, the conventional ink jet head of
FIG. 6
requires the wire bonding or the TAB bonding, the mounting and bending of the flexible wiring board
25
and the soldering in order to provide the connection pads
24
on the bottom-side surface of the wiring board
25
, and it is difficult to achieve simple, inexpensive assembly processes.
Further, Japanese Patent Application No. 9-148062, which is assigned to the owner of the present invention, discloses another conventional ink jet head.
FIG. 7
is a cross-sectional view of the conventional ink jet head of the above-mentioned application.
As shown in
FIG. 7
, the conventional ink jet head includes a glass substrate
31
in which a via hole
32
is formed. A conductive material is plated in the via hole
32
, and the via hole
32
serves as a conductive through hole in the glass substrate
31
. The conventional ink jet head of
FIG. 7
further includes an ink supply hole
37
, an ink chamber
38
, and a nozzle hole
39
. An oscillation plate
33
under the ink chamber
38
is provided above the glass substrate
31
, and a counter electrode
34
which faces the oscillation plate
33
through an internal space is provided in a recessed portion of the glass substrate
31
.
In the conventional ink jet head of
FIG. 7
, a bump-plated conductor
35
is provided on the bottom of the glass substrate
31
. The counter electrode
34
is electrically connected to the bump-plated conductor
35
by the via hole
32
. A driving voltage between the counter electrode
34
and the oscillation plate
33
is externally supplied from the
Feggins K.
Greenberg & Traurig, LLP
Le N.
Ricoh & Company, Ltd.
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