Etching a substrate: processes – Forming or treating thermal ink jet article
Reexamination Certificate
1999-11-03
2002-07-09
Gulakowski, Randy (Department: 1746)
Etching a substrate: processes
Forming or treating thermal ink jet article
C438S021000, 43
Reexamination Certificate
active
06416680
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an ink-jet recording head, its manufacturing method and an ink-jet recording device wherein a piezoelectric element is formed in a part of a pressure generating chamber communicating with a nozzle aperture for jetting an ink droplet via a diaphragm so that an ink droplet is jetted by the displacement of the piezoelectric element.
BACKGROUND ART
For an ink-jet recording head wherein a part of a pressure generating chamber communicating with a nozzle aperture for jetting an ink droplet is constituted by a diaphragm and an ink droplet is jetted from the nozzle aperture by deforming the diaphragm by a piezoelectric element and pressurizing ink in the pressure generating chamber, two types of a type that a piezoelectric actuator in a longitudinal vibration mode for extending or contracting a piezoelectric element axially is used and a type that a piezoelectric actuator in a flexural vibration mode for bending a piezoelectric element is used are realized.
For the former, the volume of a pressure generating chamber can be varied by touching the end face of a piezoelectric element to a diaphragm and a head suitable for high density printing can be manufactured, however, on the other hand, there is a problem that a difficult process for cutting a piezoelectric element in the form of the tooth of a comb in accordance with the arrangement pitch of nozzle apertures and work for positioning and fixing the cut piezoelectric element over a pressure generating chamber are required and its manufacturing process is complicated.
In the meantime, for the latter, a piezoelectric element can be fixed on a diaphragm in a relatively simple process for sticking a green sheet which is piezoelectric material in accordance with the shape of a pressure generating chamber and burning it, however, on the other hand, there is a problem that area to some extent is required because flexural vibration is utilized and high density arrangement is difficult.
In the meantime, to solve the problem of the recording head equivalent to the latter, as disclosed in Japanese published unexamined patent application No. Hei5-286131, a recording head wherein a piezoelectric element is independently formed every pressure generating chamber by forming a uniform piezoelectric material layer on the whole surface of a diaphragm by thin film technique and cutting the piezoelectric material layer in a shape corresponding to each pressure generating chamber by lithography is proposed.
Hereby, there is an advantage that work for sticking a piezoelectric element on a diaphragm is not required, not only a piezoelectric element can be fixed by a precise and convenient method such as lithography but the piezoelectric element can be thinned and high speed driving is enabled. In this case, a piezoelectric element corresponding to each pressure generating chamber can be driven by providing at least only an upper electrode every pressure generating chamber with a piezoelectric material layer provided on the whole surface of a diaphragm.
In the recording head using such a piezoelectric actuator in a flexural mode, a lead electrode for supplying voltage for driving a piezoelectric element corresponding to each pressure generating chamber is provided corresponding to each pressure generating chamber.
However, as described above, there is a problem that large stress is readily caused by the driving of a piezoelectric element in a connection (hereinafter called a contact) between a piezoelectric element corresponding to each pressure generating chamber and a lead electrode, and a crack and breaking may be caused.
There is also a problem that as a lead electrode is connected to a contact, displacement by applying voltage is small, compared with that in another part, however, nevertheless, as compliance is not small, compared with that in another part, jetting speed is deteriorated and driving voltage is increased.
Further, there is a problem that a crack is readily made in a piezoelectric layer in the vicinity of such a contact hole.
There is also a case that a piezoelectric element is sequentially pulled out over the peripheral wall of a pressure generating chamber to supply voltage for driving each piezoelectric actuator, however, in this case, there is a problem that a crack is readily made in a part in which a piezoelectric element crosses a boundary between a pressure generating chamber and the peripheral wall of a piezoelectric layer.
In the meantime, in the above ink-jet recording head, structure in which a diaphragm in a part corresponding to both sides in the direction of the width of a piezoelectric element is thinned is proposed to enhance the efficiency of the displacement of a diaphragm by the driving of the piezoelectric element. However, if displacement is increased as described above, a tendency that breaking such as a crack is readily caused particularly in the vicinity of the above peripheral wall of a pressure generating chamber or in the vicinity of a contact hole is promoted.
The problem that jetting speed is deteriorated and driving voltage is increased and the problem that breaking such as a crack is readily caused in the vicinity of the peripheral wall of a pressure generating chamber or in the vicinity of a contact hole come into question particularly in case a piezoelectric material layer is formed by film forming technique. That is, it is because a piezoelectric material layer formed by film forming technique is very thin and the rigidity is low, compared with that of a piezoelectric material layer in which a piezoelectric element is stuck.
The present invention is made in view of such a situation and the object is to provide an ink-jet recording head, its manufacturing method and an ink-jet recording device wherein a crack, breaking and others due to stress concentration in a contact are prevented and the efficiency of displacement in the contact can be prevented from being deteriorated.
The present invention is made in view of such a situation and the object is to provide an ink-jet recording head, its manufacturing method and an ink-jet recording device wherein a crack and others in a piezoelectric element, in the vicinity of the peripheral wall of a pressure generating chamber of a piezoelectric layer and in the vicinity a contact hole are prevented and durability can be secured.
DISCLOSURE OF THE INVENTION
A first embodiment of the present invention to solve the above problems relates to an ink-jet recording head based upon an ink-jet recording head wherein plural pressure generating chambers each of which communicates with a nozzle aperture are formed and a piezoelectric element at least including a lower electrode, a piezoelectric layer and an upper electrode is formed in an area corresponding to one of the plural pressure generating chambers and characterized in that a connection between a lead electrode for applying voltage to the piezoelectric element and the piezoelectric element is provided in an area opposite to a passage communicating with the pressure generating chamber other than the area opposite to the above pressure generating chamber.
According to such a first embodiment, as the connection between the lead electrode and the piezoelectric element is formed in an area other than the area opposite to the pressure generating chamber, the quantity of displacement of the pressure generating chamber by the piezoelectric element can be increased.
A second embodiment of the present invention relates to an ink-jet recording head based upon the first embodiment and characterized in that a narrow part which communicates with the end far from the above nozzle aperture of the above pressure generating chamber and at least one of the width and the depth of which is smaller than that of the pressure generating chamber and a communicating part which communicates with the pressure generating chamber via the narrow part are provided and a connection between the above piezoelectric element and the above lead electrode is provided in an area opposite to the above communica
Akahane Fujio
Matsuzawa Akira
Mitsuzawa Toyohiko
Sakai Shinri
Ahmed Shamim
Gulakowski Randy
Seiko Epson Corporation
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