Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2001-06-26
2003-10-28
Vo, Anh T. N. (Department: 2061)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06637869
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ink jet type printer head and more particularly to an improvement to implement firm fixation of piezoelectric elements and a vibrating plate in the ink jet type printer head in which ink is jetted from a nozzle and the ink is fed from an ink pool by stacking the piezoelectric elements on a pressure chamber plate on which a plurality of pressure chambers each communicating with the nozzle and the ink pool is formed by boring holes and by individually changing a volume of each of the pressure chambers.
The present application claims priority of Japanese Patent Application No.2000-191190 filed on Jun. 26, 2001, which is hereby incorporated by reference.
2. Description of the Related Art
In recent years, attention is focusing on non-impact type printers because they can be operated at a low noise level during printing and because they can provide high speed printing. Among them, an ink jet type printer in particular attracts interest of users, which performs printing of characters, graphics, photographs or a like by jetting ink drops in a liquid state from a printer head to cause the ink drops to adhere to printing paper and which enables high speed printing and printing on ordinary paper, without special fixing processing. Thanks to these advantages, a variety of ink jet type printers are proposed and put into commercial production.
FIG. 6
to
FIG. 10
c
show operations in a conventional ink jet type printer head in which jetting of ink and replenishing with ink are achieved by changing a volume of a pressure chamber using expansion/contraction deformation effects (uni-morph mode) of piezoelectric elements.
FIG. 6
is a conceptual diagram showing assembly of the conventional ink jet type printer head. The conventional ink jet type printer head is configured by stacking and bonding a nozzle plate
100
having a nozzle
101
for jetting ink, an ink pool plate
200
in which an ink pool (reservoir)
201
is formed, an ink feeding plate
300
in which ink feeding ports
301
are formed, a pressure chamber plate
400
in which a pressure chamber
401
is formed as through holes, a vibrating plate
500
and piezoelectric elements
600
. An ink communicating section
700
is used to communicate the nozzle
101
with the pressure chamber
401
. The ink communicating section
700
is provided commonly to the ink pool plate
200
and the ink feeding plate
300
. An ink sucking port
800
used to feed ink from an ink tank (not shown) to the ink pool
201
is formed in a manner that it penetrates the ink feeding plate
300
, the pressure chamber plate
400
, and the vibrating plate
500
.
Ordinarily, the piezoelectric elements
600
are bonded in advance with the vibrating plate
500
. When these components are assembled, by using an alignment hole
900
, as a reference, formed in each of the plates, the vibrating plate
500
, pressure chamber plate
400
, ink feeding plate
300
, ink pool plate
200
, and nozzle plate
100
are individually or collectively positioned and bonded to each other. An internal structure of the ink jet type printer head formed by the bonding/assembling work is partially taken and shown as a cross-sectional perspective in FIG.
7
.
Next, operations of the expansion/contraction deformation in the piezoelectric element
600
and the vibrating plate
500
will be described by referring to
FIGS. 7
,
8
, and
9
.
As shown in
FIG. 8
, at a place corresponding to a position of each of pressure chambers
401
,
401
, . . . on the pressure chamber plate
400
existing on the vibrating plate
500
is stacked each of the piezoelectric elements
600
in a bonded manner. On a face and back of each of the piezoelectric elements
600
are formed an outer electrode
600
a
and an outer electrode
600
b
respectively. Each of the piezoelectric elements
600
is polarized, for example, in a direction shown by arrows “P” from the outer electrode
600
a
to the outer electrode
600
b
. (The direction in which the piezoelectric elements
600
are polarized may be reverse.)
The outer electrode
600
b
is directly and electrically connected to the vibrating plate
500
and is connected through the vibrating plate
500
serving as an electrode being common to each of the piezoelectric elements
600
to one pole of a driving power source
1000
of a pulse generator or a like.
Moreover, to the outer electrode
600
a
of each of the piezoelectric elements
600
is individually connected an electric signal line
601
. Each of the piezoelectric elements
600
is connected through each of the electric signal lines
601
and each of ON/OFF controlling switch circuits
602
mounted to each of the piezoelectric elements
600
to the other pole of the driving power source
1000
.
When a printing instruction is input, the ON/OFF controlling switch circuit
602
is turned ON and a voltage from the driving power source
1000
is applied to the piezoelectric elements
600
. As a result, the piezoelectric elements
600
attempt to contract, by piezoelectric effects, in a direction of “e” as shown in FIG.
9
. However, in the piezoelectric elements
600
, an amount of distortion in a face being bonded to the vibrating plate
500
, since it is limited by a load of the vibrating plate
500
, is made smaller than that in the face on a reverse side. Due to an asymmetry in the amount of distortion, the bonded portion between the piezoelectric elements
600
and the vibrating plate
500
is deformed in a manner to be extruded in a direction of “f” as shown in FIG.
9
. This causes a volume in the pressure chamber
401
to decrease and ink existing in the pressure chamber
401
to be pressurized.
FIGS. 10A
,
10
B, and
10
C are cross-sectional views showing configurations of
FIG. 7
taken along a line B—B to explain jetting operations of ink.
FIG. 10A
shows an initial state in which the ink pool
201
, ink feeding port
301
, pressure chamber
401
, and nozzle
101
including its top end are filled with ink. When the ON/OFF controlling switch circuit
602
is turned ON in accordance with printing instruction, a voltage is produced in the piezoelectric element
600
and, as a result, the piezoelectric element
600
is deformed in a manner to be extruded in a direction “g” as shown in FIG.
10
B. This causes ink in the pressure chamber
401
to be pressurized and the pressure in the pressure chamber
401
to be released to the nozzle
101
and the ink feeding port
301
. As a result, ink is jetted on the nozzle
101
. Then, when the ON/OFF controlling switch circuit
602
is turned OFF and electric charges in the piezoelectric element
600
are discharged, the piezoelectric element
600
is returned elastically to a direction “h” as shown in FIG.
10
C. By this movement, an amount of ink being equivalent to an amount that has flowed out from the pressure chamber
401
by the jetting of ink is fed from the ink pool
201
through the ink feeding port
301
to the pressure chamber
401
and the pressure chamber
401
is again filled with the ink and a series of operations is terminated. In actual operations, the series of operations is performed at high speed so that printing is done.
However, the ink jet type printer head having such the configurations as described above has a problem. That is, if the piezoelectric element
600
is to be bonded to the vibrating plate
500
after the vibrating plate
500
and pressure chamber plate
400
have been bonded to each other in assembling process, warp occurs at a place corresponding to a position of the pressure chamber
401
on the vibrating plate
500
by a load produced when the piezoelectric element
600
is bonded to the vibrating plate
500
, failing to impose a proper load between the piezoelectric element
600
and the vibrating plate
500
and making it difficult to reduce thickness of the bonded portion.
Moreover, the thickness of the bonded portion is made non-uniform, thus causing a detrimental effect that dispersion in characteristics of expansion/contraction de
Dickstein Shapiro Morin & Oshinsky LLP.
Fuji Xerox Co. Ltd
Vo Anh T. N.
LandOfFree
Ink jet type printer head does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ink jet type printer head, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ink jet type printer head will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3121548