Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
1997-03-07
2002-08-27
Budd, Mark O. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S328000, C347S068000, C347S070000
Reexamination Certificate
active
06440174
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a piezo-electric/electrostrictive film type chip, which is an integrated body of piezo-electric/electrostrictive film type elements. More specifically, the present invention relates to a piezo-electric/electrostrictive film type chip which is suitably applicable to an ink-jet print head.
BACKGROUND ART
In recent years, as one of mechanisms for increasing a pressure in a pressurizing room formed in a substrate, a piezo-electric/electrostrictive film type element is known in which a volume of the pressurizing room is changed by a displacement of a piezo-electric/electrostrictive working portion formed on a wall of the pressurizing room. Such a piezo-electric/electrostrictive film type element has been used as an ink pump of a print head used for an ink-jet printer, or the like, which has a mechanism of supplying an ink into a pressurizing room and filling the pressurizing room with an ink, increasing a pressure of the pressurizing room by a displacement of a piezo-electric/electrostrictive working portion, thereby an ink fine powder is expelled from a nozzle hole connected to the pressurizing room so as to print letters.
FIG. 4
shows one embodiment of an ink-jet print head (one portion) in which the conventional and known piezo-electric/electrostrictive film type element is used as an actuator. The ink-jet print head was formed by unitarily connecting a piezo-electric/electrostrictive film type chip
10
consisting of a plurality of piezo-electric/electrostrictive actuators
20
and an ink nozzle member
11
having a plurality of nozzle holes
12
each corresponding to each of the plurality of piezo-electric/electrostrictive actuators
20
. Ink supplied to pressurizing rooms
30
formed in piezo-electric/electrostrictive actuators
20
is expelled through nozzle holes
12
arranged in an ink nozzle member
11
.
The ink nozzle member
11
includes a thin and plane nozzle plate
13
provided with a plurality of nozzle holes
12
, a thin and plane orifice plate
15
provided with a plurality of orifice holes
14
. The nozzle plate
13
and the orifice plate
15
are laminated so as to sandwich a flow path plate
16
and connected by an adhesive, or the like, so as to have a unitary structure. Inside the ink nozzle member
11
, there are formed flow paths
17
for expelling ink which introduces the ink into nozzle holes
12
and flow paths
18
for supplying ink which introduces the ink into the orifice holes
14
. Incidentally, the ink nozzle member
11
is usually made of plastic or metal.
The piezo-electric/electrostrictive actuator
20
includes a ceramic substrate
21
and a piezo-electric/electrostrictive working portion
22
unitarily formed in the ceramic substrate
21
. The ceramic substrate
21
has a unitary structure in which a thin and plane closure plate
23
and a connecting plate
24
are laminated with a spacer plate
25
sandwiched therebetween. In the connecting plate
24
are formed a first through opening
26
and a second through opening
27
each corresponding to an orifice hole
14
formed in the orifice plate
15
of the ink nozzle member
11
.
In the spacer plate
25
are formed a plurality of window portions
28
. The spacer plate
25
is laminated on the connecting plate
24
so that the first through opening
26
and the second through opening
27
arranged in the connecting plate
24
correspond to each of the window portions
28
. On the other side of the spacer plate
25
opposite to the side of the connecting plate
24
, the closure plate
23
is superposed, and the openings of the window portions
28
are closed by the closure plate
23
.
Thus, pressurizing rooms
30
are formed in the ceramic substrate
21
.
On the outer surface of the closure plate
23
of the ceramic substrate
21
, each of the piezo-electric/electrostrictive working portion
22
is arranged on positions corresponding to each of the pressurizing rooms
30
. Here, the piezo-electric/electrostrictive working portion
22
consists of a lower electrode
31
, a piezo-electric/electrostrictive layer
32
, and an upper electrode
33
.
An ink-jet print head is formed by unitarily connecting a piezo-electric/electrostrictive film type chip
10
and an ink nozzle member
11
. When an ink-jet print head is unitarily formed, throughholes such as the first through opening
26
and the second through opening
27
formed in the piezo-electric/electrostrictive actuator
20
and throughholes such as a plurality of orifice holes
14
in an ink nozzle member
11
should keep a relation of accurate positions.
In such a unitary connection of the piezo-electric/electrostrictive film type chip
10
and the ink nozzle member
11
, a pin hole
42
has been conventionally formed around an edge portion of the piezo-electric/electrostrictive film type chip
10
as shown in
FIG. 5. A
constructing pin (not shown) is inserted to the pin hole
42
for an absolute positioning so as to connect the piezo-electric/electrostrictive film type chip
10
to the ink nozzle member
11
. Incidentally,
43
denotes an auxiliary hole into which an auxiliary pin (not shown) is inserted so as to avoid rotational slippage between the piezoelectric/electrostrictive film type chip
10
and the ink nozzle member
11
.
However, demands of improving resolution and printing speed ability of an ink-Jet printer have been further increasing in recent years. As a result, as the degree of integration of a piezo-electric/electrostrictive film type chip
10
is increased, many nozzles are required. Along with the demand, enlargement of a piezo-electric/electrostrictive film type chip
10
has been further required. According to the enlargement of a piezoelectric/electrostrictive film type chip
10
, a problem has arisen because the preciseness of positions of the pin hole
42
and a throughhole of the piezo-electric/electrostrictive actuator
20
deteriorates because the distance between the pin hole
42
and, the piezo-electric/electrostrictive actuator
20
located furthermost from the pin hole
42
is elongated when the pin hole
42
is formed in the edge portion of a piezo-electric/electrostrictive film type chip
10
. This is because a ceramic substrate
21
is formed by a method including the steps of molding a ceramic green sheet, punching, laminating, unitarily firing, and therefore, a firing shrinkage of about 20% of a ceramic varies depending on the parts, which makes an absolute value of a variance large as the piezo-electric/electrostrictive film type chip
10
is enlarged.
Therefore, an object of the present invention is to provide a piezo-electric/electrostrictive film type chip, in which deterioration of preciseness of positions of a pin hole and a throughhole of a piezo-electric/electrostrictive actuator is minimized and which can be precisely connected with an ink nozzle member.
DISCLOSURE OF THE INVENTION
That is to say, according to the present invention, there is provided a piezo-electric/electrostrictive film type chip comprising:
a ceramic substrate having a spacer plate having a windows-disposed pattern comprising at least a plurality of window portions and a thin closure plate for closing the window portions that is unitarily connected with the spacer plate; and
a piezo-electric/electrostrictive working portion having a lower electrode, a piezo-electric/electrostrictive layer, and an upper electrode, each being formed in the form of a layer and laminated in this order at a closure portion of the window on the outer surface of the closure plate by a film formation method;
wherein a pin hole for positioning is formed in or near the center of gravity of the windows-disposed pattern.
A shortest distance A between window portions of the spacer plate and a pin hole for positioning preferably satisfies the formula 0.5×t≦A (t: thickness of the spacer plate). In this case, t is preferably 0.5 mm or less.
Incidentally, a spacer plate is not a green sheet but a virtual portion specified by drawing a virtual line on a completed piezo-electric electrostrictive film ty
Akahane Fujio
Kamoi Kazumi
Katakura Takahiro
Shinada Satoshi
Takahashi Nobuo
Parkhurst & Wendel L.L.P.
Seiko Epson Corporation
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