Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2000-05-31
2001-10-02
Dougherty, Thomas M. (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C310S331000, C310S370000, C310S354000, C310S365000
Reexamination Certificate
active
06297577
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to an ink jet recording apparatus. More particularly, the invention concerns an electro-mechanical transducer employed in the ink jet recording apparatus.
2. Background of the invention
Conventionally, an electro-mechanical transducer having piezo-electric members is employed in an ink jet recording device. The piezo-electric member vibrates in different vibrating modes depending upon its shape, the direction that the member is polarized, or the direction that an electronic field applied thereto. For example, where the piezo-electric member is in the form of plate which is rectangular in cross-section and is polarized in a direction along its transverse direction, applying an electronic field along its polarized direction makes the piezo-electric member contract along its longitudinal direction and expand along its transverse direction, while applying an electronic field to the piezo-electric member reverse to the polarized direction makes the piezo-electric member expand along its longitudinal direction and contract along its transverse direction. A vibration along the longitudinal direction will be referred to as “a d(
31
) mode” while a vibration mode along the transverse direction will be referred to as “a d(
33
) mode”. Further, applying the electronic field to the piezo-electric member perpendicular to its polarized direction introduces therein a shear stress along its surface. This vibration mode is referred to as “a d(
15
) mode” hereinafter.
Each prior art electro-mechanical transducer employs one of these vibration modes, the d(
33
) or d(
31
) mode being mainly employed among them. Further, a prior art ink jet recording device includes the electro-mechanical transducer. Each transducer has therein an ink chamber in which an elongated piezo-electric member is arranged. The piezo-electric member is vibrated according to image signals. Then, in response to displacements of the piezo-electric member and the resultant energy generated in the ink, ink droplets are ejected from the ink chamber through a nozzle formed in a wall of the chamber.
For instance, U.S. Pat. No. 4,752,788 discloses an ink jet head which is shown in FIG.
1
. This ink jet head
10
includes a piezo-electric member
11
in which a plurality of parallel slots
12
are formed, and a plate
13
for covering the slots
12
to define respective ink chambers
14
. Each slot
12
has at its bottom portion a pair of slits extending in a longitudinal direction thereof so as to define therebetween an elongated mount
15
. An electrode
16
is arranged on the upper surface of the mount
15
, and another electrode
17
is provided on a lower surface of the piezo-electric member
11
opposing electrode
16
. In operation of the head
10
thus constructed, applying a voltage between the electrodes
16
and
17
causes the mount
15
to deform, which varies a volume of the ink chamber
14
. This energizes ink in the chamber
14
so that a droplet of the ink is ejected through a nozzle which is not shown.
Further, Japanese Patent Laid-Open Publication No. 6-143563 discloses another ink jet head
20
depicted in FIG.
2
. The head
20
has a first base plate
21
. The plate
21
includes a plurality of parallel slots
22
which are covered by a compliant film
23
to define a plurality of corresponding ink chambers
24
. The head
20
also has a second base plate
25
. This plate
25
has thereon a plurality of mutually spaced piezo-electric vibrators
26
for drive as well as a dummy piezo-electric vibrator
27
. These piezo-electric vibrators
26
and
27
are constructed by superimposing piezo-electric thin layers and electrode layers alternately. The second base plate
25
is arranged on the first base plate
21
so that each vibrator
26
contacts with the compliant film
23
over the ink chamber
24
. The drive and dummy vibrators
26
and
27
are typically formed by first bonding a layered piezo-electric plate on the plate
25
and second forming grooves in the plate at equal intervals. The first base plate
21
, compliant film
23
, and the second base plate
25
, including the vibrators
26
and
27
, are held securely by rigid plates
28
and
29
using bolts. In operation of the ink jet head
20
thus constructed, applying voltage on the vibrator
26
causes it to deform, which moves the complaint film
23
to force the ink so that the volume of the ink chamber
24
varies and then an ink droplet is ejected through a nozzle which is not shown.
However these prior arts ink jet heads employs one of d(
31
), d(
33
), or d(
15
) vibration modes, each of which provides for only a small deformation with the piezo-electric member. Therefore, the ink is not sufficiently energized in response to the image signals.
Further, in the above mentioned systems, the vibration of one piezo-electric member is transmitted to the neighboring ink chambers and piezo-electric members, i.e., a cross-talk from chamber to chamber is occurred, which results in unexpected ink ejections from those ink chambers so that the resultant image of a recording device is damaged.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved piezo-electric transducer which is capable of providing a piezo-electric member with a large deformation to eject an ink droplet vigorously.
Another object of the invention is to provide an improved piezo-electric transducer which is capable of ejecting ink droplets vigorously.
Further object of the invention is to provide an improved ink jet recording apparatus which employs a piezo-electric transducer capable of providing a piezo-electric member with a large deformation and then ejecting ink droplets vigorously.
In accordance with these objects, the present invention provides an ink jet recording apparatus which includes an ink chamber in which an ink is filled, said ink chamber having a nozzle from which the ink is ejected; a strip member which is provided along with said ink chamber, said strip member being extending in an extending direction from a first portion corresponding to said ink chamber to a second portion not corresponding to said ink chamber; and driver which is connected with said strip member to induce a displacement of said first portion in a direction orthogonal to the extending direction.
Further the present invention provides an electro-mechanical device which includes a base member; a piezo-electric member which has a strip shape extending in an extending direction, said piezo-electric member having a first surface along with said extending direction and a second surface opposing to said first surface, a part of said first surface being fixedly connected with said base plate, said second surface having at least one groove; a first electrode which is disposed on said first surface; and a second electrode which is disposed on said second surface throughout said groove.
Furthermore the present invention provides an electro-mechanical device which includes a strip member which has a strip shape extending in an extending direction, said strip member having a surface along the extending direction; a piezo-electric member which is fixedly connected with said surface at an edge portion of said strip member with respect to said extending direction; and a pair of electrodes which is provided on said piezo-electric member.
Moreover the present invention provides an electro-mechanical device which includes a piezo-electric member having a length (
1
) in an extending direction, said piezo-electric member having a first surface parallel to said extending direction, and having a second surface opposing to said first surface; a first electrode which is provided on said first surface; a second electrode which is provided on a first portion of said second surface, said first portion having a length (t) with respect to said extending direction from a first edge of said piezo-electric member; a base member on which a second portion of said piezo-electric member is fixedly connected,
Higashino Kusunoki
Hotomi Hideo
Masaki Kenji
Dougherty Thomas M.
Minolta Co. , Ltd.
Sidley Austin Brown & Wood
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