Incremental printing of symbolic information – Ink jet – Ejector mechanism
Reexamination Certificate
2002-05-28
2004-02-10
Meier, Stephen D. (Department: 2853)
Incremental printing of symbolic information
Ink jet
Ejector mechanism
Reexamination Certificate
active
06688732
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an inkjet recording head, which is capable of incorporation into information equipment such as a word processor, facsimile, and printer, a method for manufacturing the same, and an inkjet recording device. In particular, the present invention relates to an inkjet recording head configured to allow high-density arrangement in a two-dimensional array of piezoelectric elements and facilitate mass hie production thereof, a method for manufacturing such an inkjet recording head, and an inkjet recording device having such an inkjet recording head.
2. Description of the Related Art
In recent years, an impact recording process has attracted much attention for its small noise in recording and a high recording speed thereof. Among other impact recording processes, an inkjet recording process used in inkjet printers has been in wide use. The inkjet printer allows ink droplets to be ejected from the recording head and attached onto recording paper so that characters, figures and photographs are printed at a high speed. The inkjet printer is capable of recording the images onto plain paper without using a special fixation processing. According to a known inkjet recording process called drop-on-demand inkjet recording scheme, an electromechanical transducer such as a piezoelectric actuator is used to generate pressure waves (acoustic waves) in pressure chambers filled with ink, thereby allowing ink droplets to be ejected from the nozzles disposed in communication with the pressure chambers.
An inkjet recording head using the drop-on-demand inkjet scheme is described in JP Patent Publication No. Sho 56-64877.
FIGS. 1A
to
1
C show the conventional inkjet recording head described in the publication.
FIG. 1A
is a longitudinal sectional view of the essential parts of the inkjet recording head,
FIG. 1B
a partially-broken top plan view thereof, and
FIG. 1C
a sectional view taken along the line c—c of FIG.
1
B.
The inkjet recording head described in the publication has a base plate
44
and a diaphragm
42
which are coupled together to form a plurality of pressure chambers
45
therebetween. An ink nozzle, or orifice
43
, is formed at one end of each pressure chamber
45
. A plurality of rectangular piezoelectric elements
41
are mounted on the diaphragm
42
corresponding to the respective pressure chambers
45
The piezoelectric elements
41
are electrically connected to a pulse generator
40
. The pressure chamber
45
is supplied with ink from an ink reservoir
47
through an ink supply tube
46
. The piezoelectric elements
41
are made of piezoelectric ceramic, and more particularly, PZT (lead zirconate titanate).
In the conventional inkjet recording head as described above, the piezoelectric elements
41
are manufactured by machining a piezoelectric ceramic plate to configure predetermined size and shape. Examples of he method for machining the piezoelectric elements
41
with high precision include a dicing saw technique such as for cutting or trenching by using the rotation of a disc containing diamond particles (dicing blade), and a wire saw technique. These high-precision machining methods for piezoelectric elements, although suited to linear machining, are incapable of working the piezoelectric ceramic plate (piezoelectric plate) into arbitrary shapes.
An example of a manufacturing method for forming a piezoelectric plate into an arbitrary shape is described in JP Patent Laid-Open Publication No. Hei 11-207970. The manufacturing method described in this publication is as follows. Initially, a sheet of foaming agent is bonded onto a dummy glass plate, and a piezoelectric film is laminated thereon. A resist is applied thereon and patterned for mask portions. Thereafter, the piezoelectric film is subjected to cutting by sandblasting at regions other than those covered by the mask portions. Subsequently, the resist is removed. The resultant piezoelectric plates are subjected to positioning onto the ink reservoirs and placed on a conductive film formed on the diaphragm before the dummy glass plate is removed. Then, electrodes are mounted on the piezoelectric film to obtain the inkjet recording head. Using the manufacturing method described in the publication, the piezoelectric film can be formed into arbitrary shapes according to the mask pattern.
In the field of the inkjet recording heads, such an inkjet recording head having a two-dimensional array of a number of nozzles (hereinafter, this type of the inkjet recording head is referred to as a matrix head) is expected as the next-generation head in view of the high-density nozzle arrangement with suppressed increase in the head size. The technique described in the publication relates to an inkjet recording head having a plurality of piezoelectric elements arranged only in one dimension. It is silent as to the provision of a number of piezoelectric elements arranged in a two dimensional array at a high density to form a matrix head.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a method for manufacturing an inkjet recording head by which a piezoelectric plate can be formed into arbitrary shapes and arranged at a high-density, i.e., in two-dimensional array of a number of piezoelectric elements as a matrix head, and which can be manufactured by simple manufacturing processes.
It is another object of the present invention to provide an inkjet recording head manufactured by such a manufacturing method, and an inkjet recording device incorporating such an inkjet recording head.
To achieve the foregoing objects, the present invention provides, in a first aspect thereof, a method for manufacturing an inkjet recording head which includes a two-dimensional array of a plurality of pressure chambers each communicating with a common ink reservoir, at least one diaphragm constituting part of walls of the pressure chambers, and a plurality of piezoelectric elements coupled to the diaphragm so as to correspond to the pressure chambers, the piezoelectric elements being activated to apply a pressure wave to ink in the pressure chambers so that ink droplets are ejected from nozzles which communicates with the respective pressure chambers.
A preferred embodiment of the method of the first aspect of the present invention includes the steps of: temporarily bonding a piezoelectric plate onto a substrate for allowing the substrate to be released from the piezoelectric plate; affixing a mask film onto the piezoelectric plate; patterning the mask film into a piezoelectric element mask pattern; subjecting the piezoelectric plate to sandblasting from above the piezoelectric element mask pattern to form a piezoelectric element array including a plurality of piezoelectric elements arranged in a two-dimensional array on the substrate; bonding the piezoelectric elements of the piezoelectric element array as a unit onto the diaphragm; and removing the substrate from the piezoelectric elements after the sandblasting.
The term “piezoelectric plate” as used in this text means a plate of a piezoelectric material such as a piezoelectric ceramic to be configured into a plurality of piezoelectric elements.
According to the method of the first aspect of the present invention, the piezoelectric plate can be cut into arbitrary shapes with ease to facilitate provision of a number of piezoelectric elements each releasable from the substrate. In addition, since the plurality of piezoelectric elements can be formed on the substrate as a piezoelectric element array having a two-dimensional arrangement, a high-density and two-dimensional array of a number of piezoelectric elements can be easily manufactured to form a matrix head.
The piezoelectric plate is preferably patterned by sandblasting. The patterning of the piezoelectric plate by using the sandblasting technique allows the piezoelectric elements to be formed on the diaphragm with ease irrespective of the number and arrangement of piezoelectric elements.
JP Patent Laid-Open
Mitsuhashi Masashige
Umehara Shigeru
Do An H.
Fuji 'Xerox Co., Ltd.
Meier Stephen D.
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