Inkjet recording head and method of producing the same

Incremental printing of symbolic information – Ink jet – Ejector mechanism

Reexamination Certificate

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Details

C347S071000

Reexamination Certificate

active

06554406

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet printing head and a production thereof and in particular, to an ink jet printing head for discharging an ink droplet to a recording medium for image printing and a production method of the ink jet printing head.
2. Description of the Related Art
Conventionally, for example, this type of ink jet printing head is disclosed in Japanese Patent Publication No. A8-58089 [1].
FIG. 8
is a cross sectional view schematically showing a printing head identical to the one disclosed in Citation [1]. As shown here, the printing head, the conventional printing head includes: a nozzle plate
21
, a pool plate
22
, a supply perforation plate
23
, a sealing plate
24
, a pressure generating chamber
25
, and a vibration plate
26
which are layered and to which an actuator
27
is mounted.
Moreover, in the nozzle plate
21
, a nozzle
28
is formed for discharging ink. This nozzle
28
is connected to the pressure generating chamber
30
via a ink through hole
29
formed in the pool plate
22
, the ink supply hole plate
23
, and the sealing plate
24
. Moreover, this pressure generating chamber
28
is connected to the ink pool
33
formed in the pool plate
22
, via a supply communication path
31
formed in the sealing plate
24
and a ink supply hole
32
formed in the ink supply hole plate
23
.
Thus, in the conventional method, a plurality of substrates having a nozzle
28
and the ink pool
33
are layered and an actuator
30
is attached to prepare an ink jet printing head. For attachment of the plurality of plates, adhesive is used.
When using adhesive for attachment between plates, there is a danger of adhesive clogging in the hole or groove such as a nozzle and nozzle communication hole.
In order to solve this problem, Japanese Patent Publication No. A5-330067 [2] discloses a technique to provide an escape groove in the vicinity of the nozzle so as to clear an unnecessary portion of the adhesive.
FIG. 9
is a perspective view of an ink jet printing head disclosed in Citation [2]. As shown here, a liquid adhesive
37
is applied as a thin film onto the surface of a plate
34
by way of ‘transfer’ or ‘printing’, and a plate
38
is mounted thereon.
The plate
34
has on its surface an escape groove
36
for cleaning an unnecessary portion of the adhesive to suppress intrusion of the adhesive into the nozzle groove
35
. Moreover, when such plates are multi-layered, the adhesive thickness values are identical.
However, it can not be said sufficient to provide an escape groove of the adhesive.
In general, in an ink jet printing head as shown in
FIG. 8
, the plate thickness differs depending on its purpose. For example, the vibration plate
26
should be thin enough to effectively transfer the vibration of the actuator
27
to the pressure generating chamber
30
. Moreover, the ink plate
22
should be thick enough to assure a sufficient volume of the ink pool.
However, when an escape groove is to be provided as disclosed in Citation 2, in multi-layered plates having different thickness values, it is difficult to provide an escape groove in a thin plate. That is, it is impossible to form a groove having a depth greater than the thin plate thickness. It is also considered to increase width of the groove in the horizontal direction. However, if a groove has a wide width, there arise problems of plate strength and warp. Moreover, if a large groove is formed, the adhesion application area is decreased and the adhesive layer may not be uniform and have air bubbles (void).
SUMMARY OF THE INVENTION
The present invention intends to solve these problems. The object of the present invention is to provide an ink jet printing head and its production method capable of suppressing extrusion of adhesive into an ink flow path and increasing reliability and yield without causing irregularities or air bubbles (void) as well as reducing the production cost.
In order to achieve the object, claim
1
discloses an ink jet printing head comprising a plurality of substrates having a hole or groove which are attached to one another via an adhesive layer, wherein thickness of adhesive is adjusted according to a thinner substrate as a reference of two substrates to be attached to each other in such a way that the thickness of the adhesive becomes thinner as the reference substrate becomes thinner and thicker as the reference substrate becomes thicker.
Thus, according to the present invention, adhesive layer thickness is determined according to a thinner one of two adjacent substrates. Accordingly, it is possible to prevent extrusion of adhesive and clogging of a hole and groove provided on the respective substrates.
Claim
2
discloses an ink jet printing head as claimed in claim
1
, wherein the plurality of substrates are constituted by: a nozzle plate having a nozzle for discharging ink; a pool plate having an ink pool and a first nozzle communication hole; a ink supply hole plate having a ink supply hole and a second nozzle communication hole; a chamber plate having a pressure generating chamber; and a vibration plate having an actuator for generating displacement, wherein the nozzle is connected to the pressure generating chamber via the first and the second ink through holes, and the pressure generating chamber is connected to the ink pool via the ink supply hole.
Moreover, claims
3
and
4
discloses an ink jet printing head as claimed in one of claim
1
and claim
2
, wherein each of the adhesive layers is formed by an epoxy adhesive with a thickness 1 to 4 micrometers.
Thus, the present invention can further suppress extrusion of the adhesive. No air bubble (void) remains if the thickness is equal to or above 1 micrometer.
Moreover, claim
5
discloses a production method of an ink jet printing head comprising a plurality of substrates having a hole or groove which are attached to one another via an adhesive layer, wherein thickness of adhesive is adjusted according to a thinner substrate as a reference of two substrates to be attached to each other in such a way that the thickness of the adhesive becomes thinner as the reference substrate becomes thinner and thicker as the reference substrate becomes thicker.
Thus, according to the present invention, adhesive layer thickness is determined according to a thinner one of two adjacent substrates. Accordingly, it is possible to prevent extrusion of adhesive and clogging of a hole and groove provided on the respective substrates.
Moreover, claim
6
discloses an ink jet printing head production method as claimed in claim
5
, wherein the plurality of substrates are constituted by: a nozzle plate having a nozzle for discharging ink; a pool plate having an ink pool and a first nozzle communication hole; a ink supply hole plate having a ink supply hole and a second nozzle communication hole; a chamber plate having a pressure generating chamber; and a vibration plate having an actuator for generating displacement; wherein the nozzle is connected to the pressure generating chamber via the first and the second ink through holes, and the pressure generating chamber is connected to the ink pool via the ink supply hole.
Moreover, Claim claims
7
and
8
discloses an ink jet printing head production method as claimed in one of claim
5
and
6
, wherein each of the adhesive layers is formed by an epoxy adhesive with a thickness 1 to 4 micrometers.
Thus, the present invention can further suppress extrusion of adhesive and no irregularities or air bubbles (void) remain if the thickness is equal to or more than 1 micrometer.
Moreover, claim
9
discloses an ink jet printing head production method as claimed in claim
6
, comprising steps of: applying adhesive onto the nozzle plate so as to form an adhesive layer and mounting the pool plate thereon; applying adhesive onto the pool plate so as to form an adhesive layer and mounting the ink supply hole plate thereon; applying adhesive onto the ink supply hole plate so as to form an a

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