Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1999-09-08
2003-09-30
Nguyen, Lamson (Department: 2861)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06626525
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATIONS
The present invention claims priority from Japanese Patent Application No. 10-254202 filed Sep. 8, 1998, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an actuator of an ink jet recording head, for recording characters and/or pictures by jetting ink droplets to a recording medium such as a recording sheet.
2. Description of Related Art
FIG. 9
is a cross section of an actuator of a conventional ink jet recording head, showing a structure of a main portion of the actuator. This structure has a purpose of illustrating a structure of one of pressure chambers of the ink jet recording head and one of ink nozzles thereof. In this conventional structure, a space defined by nozzle plate
31
formed of a rigid material and casing
34
formed of a rigid material is used as pressure chamber
33
, which is filled with externally supplied ink
5
. Nozzle
32
for jetting ink droplet
1
is formed in nozzle plate
31
and drive plate
35
is provided within pressure chamber
33
. Drive plate
35
is formed of a piezoelectric material (or a material having large thermal expansion coefficient) and has opposite surfaces, on which electrodes
39
are formed, respectively. When a voltage is applied across electrodes
39
from power source
40
through switch
37
as an electric signal, drive plate
35
is deformed in a direction shown by, for example, an arrow by the piezoelectric effect (or thermal expansion) as shown, to pressurize ink
5
filling pressure chamber
33
to thereby jet ink droplet
1
out through nozzle
32
.
In this conventional structure, drive plate
35
is put on support portion
38
and adhered thereto as shown in
FIG. 10
(Japanese Patent Application Laid-open No. Hei 9-85946). That is, in order to control the direction of deformation constant, one of the surfaces of drive plate
35
is fixed by adhesive to support portion
38
, by which displacement thereof is restricted. Therefore, a compressive reactive force is exerted on a portion between drive plate
35
and support portion
38
as shown by horizontal inward arrows in
FIG. 10
, every time when the pressure chamber is driven.
That is, since, when the actuator having such structure is driven, a reactive force of the driving force is repetitively exerted on the adhesive layer between driving plate
35
and support portion
38
, shearing deformation tends to occur in the adhesive layer. When such shearing deformation occurs in the adhesive layer, displacement in a direction parallel to the plane of driving plate
35
is relieved thereby and, therefore, an amount of displacement of driving plate
35
in a direction shown by a thick arrow in
FIG. 10
becomes small. If such shearing deformation is considerable, driving plate
35
may be peeled off from support portions
38
by the reactive force of the driving force. In the latter case, a driving force for pressurizing ink pressure chamber
33
may not be produced at all. That is, this phenomenon may cause the life of the ink jet recording head to be shortened. Further, in such structure of the actuator, an adhering step is required in a manufacture thereof. In such adhering step, a precise positioning is necessary, with which the number of manufacturing steps may be increased. Further, since a positioning error, a variation of adhering strength and a variation of thickness of the adhering layer, etc., are reflected on a variation of the ink jet characteristics, that is, printing characteristics, manufacturing yield of the ink jet recorder may be lowered.
SUMMARY OF THE INVENTION
The present invention was made in view of the above mentioned fact and has an object to provide an ink jet recording head whose ink jetting characteristics is not influenced directly by a positioning error, a variation of adhering strength and a variation of thickness of an adhesive layer, etc., thereof which may be caused by the necessity of adhesion of a driving plate to the support portion.
Another object of the present invention is to provide an ink jet recording head capable of being manufactured without using the adhering step for adhering a driving plate to a support portion.
Another object of the present invention is to provide an ink jet recording head capable of substantially increasing the number of effective reciprocal movements of the driving plate to thereby allow a life thereof to be lengthened.
A further object of the present invention is to provide an ink jet recording head which rarely breaks down and is highly reliable.
Another object of the present invention is to provide an ink jet recording head whose variation of performance over time is minimized.
Another object of the present invention is to provide an ink jet recording head capable of being manufactured with a small number of manufacturing steps.
A still further object of the present invention is to provide an ink jet recording head with which an ink jet recorder having a uniform performance can be manufactured.
Another object of the present invention is to provide an ink jet recording head which can be manufactured with high yield.
In order to achieve the above objects, the ink jet recording head according to the present invention, which has a structure in which an ink chamber is pressurized by utilizing a buckling deformation of a driving plate, is featured by that a pressuring unit has a structure in which an adhesive layer is not influenced by displacement caused by every pressurization of the ink chamber.
That is, in an ink jet recording head including a rigid member defining a pressure chamber formed with a nozzle for jetting ink droplet and a pressuring unit for pressurizing ink filling the pressure chamber correspondingly to an electric signal, the present invention is featured by that the pressurizing unit comprises at least one beam supported at opposite end portions thereof and a support portion for supporting the opposite end portions of the beam and restricting an expansion of the beam in its longitudinal direction such that, when the beam is expanded in the longitudinal direction due to an application of the electric signal, the expanded portion of the beam is buckled into the pressure chamber.
The beam is made of a piezo-electric material. At least one electrode for applying an electric signal is formed on a surface of the beam. Alternatively, the beam may be made of a material having large thermal expansion coefficient and a heater for heating the beam upon an application of the electric signal may be provided. The beam and the support portion are preferably formed integrally. The beam and the support portion may be integrally formed from a piezo-electric material sheet by punching and the electrode is formed on the beam.
A recess for controlling a direction of buckling deformation of the beam is formed in the beam. It is possible to form such recess at a position deviated in the longitudinal direction of the beam from a center of the beam or it is possible to provide an electrode for controlling the direction of buckling deformation of the beam on the latter partially.
The pressurizing unit pressurizes ink in the pressure chamber having the nozzle for jetting ink droplet in response to the electric signal. The pressurization is performed by applying the electric signal to the beam formed continuously to the support portion for restricting the expansion of the beam in its longitudinal direction to expand the beam in the same direction to thereby buckle the beam into the pressure chamber. By this buckling deformation of the beam, ink in the pressure chamber is pressurized and jetted through the nozzle as ink droplet.
In order to realize the buckling deformation of the beam, the beam may be formed of a piezo-electric material and an electric signal is applied to an electrode provided on a surface of the beam. When the electric signal is applied to the electrode, the beam is expanded in its longitudinal direction, buckled toward the pressure chamber and pressurizes the
Kanda Torahiko
Nakamura Hirofumi
Dickstein Shapiro Morin & Oshinsky LLP.
Feggins K.
Fuji Xerox Co. Ltd
Nguyen Lamson
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