Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
1996-07-24
2001-01-23
Barlow, John (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
C310S358000
Reexamination Certificate
active
06176570
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a printer apparatus for printing an image on a recording medium by discharging a discharging medium filled in a pressure chamber from a discharge nozzle by a bimorphic effect of a piezoelectric element and a vibrating plate and to a method of production of the same.
2. Description of the Related Art
The conventional so-called “on-demand type” ink jet printer is a printer which discharges ink droplets from a nozzle in accordance with a recording signal so as to record an image on a recording medium such as paper or film. This printer enables a reduction of size and a reduction of cost, so has been rapidly spreading in recent years.
On the other hand, in recent years, particularly in the office, there has been a boom in the production of documents by computers in what is known as “desk top publishing”. Recently, there has been increased demand for printing not only characters and figures, but also color natural images such as photographs together with the characters and figures. To print a high quality natural image in this way, reproduction of halftones is very important.
In this on-demand type ink jet printer, the general methods used to discharge the ink droplets have been the method of using for example a piezoelectric element and the method of using a heat generating element. The method of using a piezoelectric element uses the deformation of the piezoelectric element to give a pressure to the ink and thereby discharge the same from the nozzle. On the other hand, the method of using the pressure of bubbles generated by heating and boiling the ink by a heat generating element to discharge the ink.
To reproduce halftones, there are the method of changing the voltage given to the piezoelectric element or the heat generating element and the pulse width so as to control the size of the droplets to be discharged, thereby making variable the diameter of the printing dots and expressing a tone and the method of including a pixel by a matrix consisting of for example 4×4 dots without a change of the dot diameter and expressing the tones by using the so-called dither method in units of this matrix.
The method of using the deformation of a piezoelectric element to give pressure to the ink and discharge the same from a nozzle includes a method in which a plurality of superposed layers of piezoelectric elements are made to linearly displaced to push the vibrating plate and a method of giving a voltage to a piezoelectric element including a single layer or two superposed layers clad to a vibrating plate so as to cause the vibrating plate to bend.
FIG.
1
and
FIG. 2
show a print head in a printer apparatus using a single-plate type piezoelectric element. This print head comprises a base
101
made of for example a photosensitive glass, a vibrating plate
102
attached to this base
101
, a piezoelectric element
103
provided on this vibrating plate
102
, and an orifice plate
105
on which the discharge nozzle
104
is formed.
On the base
101
, as shown in
FIG. 1
, an ink introduction hole
106
for introducing the ink and a pressure chamber
107
for accommodating the ink are formed. The vibrating plate
102
is attached to the base
101
so as to cover these ink introduction hole
106
and pressure chamber
107
. The piezoelectric element
103
has electrodes
108
and
109
on the upper and lower surfaces of its thickness direction as shown in
FIG. 1
, respectively, and is bonded onto the vibrating plate
102
at a position corresponding to the pressure chamber
107
by an adhesive or the like. The orifice plate
105
is provided on the surface of the base
101
opposite to the surface on which the vibrating plate
102
is provided. The discharge nozzle
104
provided on this orifice plate
105
is communicated with the pressure chamber
107
.
In this print head, when a voltage is applied to the piezoelectric element
103
, the piezoelectric element
103
deforms due to the bimorphic effect and the displacement thereof is transferred to the pressure chamber
107
via the vibrating plate
102
. Then, due to the displacement of this piezoelectric element
103
, the volume of the pressure chamber
107
is reduced and the ink filled in the pressure chamber
107
is discharged from the discharge nozzle
104
.
In the method of bending the vibrating plate by giving a voltage to a piezoelectric element including a single layer or two superposed layers adhered to the vibrating plate, however, there is a problem that it is difficult to achieve a fine pitch when adhering cut piezoelectric elements onto a vibrating plate. Further, where arranging paste-like piezoelectric elements on the vibrating plate by a means such as printing and then performing sintering, the heat resistance of the vibrating plate makes it difficult to raise the sintering temperature to 1000° C. or more, so there is the defect that the characteristic of the piezoelectric material cannot be sufficiently exhibited. Further, in the method of cutting after adhering a piezoelectric element to a vibrating plate, it is difficult to cut only the piezoelectric element without scratching the vibrating plate and, at the same time, it is not easy to always cut to a constant depth when considering the wear of the tool and the positional precision of the machine tool.
On the other hand, in the method of causing straight displacement of a plurality of layers of superposed piezoelectric elements to push the vibrating plate, the piezoelectric elements per se become expensive so there is a disadvantage in view of costs.
OBJECT AND SUMMARY OF THE INVENTION
The present invention was proposed in consideration with the above problems and has as an object thereof to provide a printer apparatus using a single or a plurality of superposed layers of piezoelectric elements and at the same time provide a method of production of a printer apparatus which stabilizes the process, brings out the full characteristics of the piezoelectric material, and further enables a fine pitch.
The present inventors engaged in intensive investigations so as to solve the above problems and consequently found the fact that it was possible to bring out the full inherent characteristics of a piezoelectric material and realize a fine pitch by providing not a single layer of a vibrating plate, but a superposed structure of a plurality of layers of vibrating plates, causing at least one layer among them to function as an original vibrating plate and not cutting up to the vibrating plate made to function as the original vibrating plate by the machining performed when cutting the piezoelectric elements, and removing the other vibrating plates remaining at the cut portions just before this by etching as an etching stop layer or the like.
Accordingly, the present invention provides a printer apparatus including a discharge nozzle; a pressure chamber communicated with this discharge nozzle; vibrating plates covering the pressure chamber; and a piezoelectric element arranged corresponding to the pressure chamber via the vibrating plates, the vibrating plates including a plurality of layers, at least one layer of the vibrating plates covering the entire pressure chamber, and the remaining layers of the vibrating plates being partially removed by using the piezoelectric element as the mask and controlled to substantially the same width as that of the piezoelectric element.
In addition, the present invention provides a method of production of a printer apparatus having a discharge nozzle, a pressure chamber communicated with this discharge nozzle, and vibrating plates covering the pressure chamber, the vibrating plates including a plurality of layers including an etching stop layer, including a first step of bonding a piezoelectric element layer onto the vibrating plates; a second step of cutting the piezoelectric element layer and the vibrating plates to a depth where the piezoelectric element layer is cut and a part of the vibrating plates remain so as to form a groove; and a third ste
Kishima Koichiro
Murakami Takaaki
Nakayama Tetsuo
Barlow John
Dickens C
Hill & Simpson
Sony Corporation
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