Piezoelectric substrate, piezoelectric element, liquid discharge head and liquid discharge apparatus

Abstract

A piezoelectric substrate of a perovskite-type oxide is expressed by a general formula of ABO3 having a laminate structure of a single crystal structure or a uniaxial crystal structure expressed by (Pb1-xMx)xm(ZryTi1-y)O3 (where M represents an element selected from La, Ca, Ba, Sr, Bi, Sb and W) and the laminate structure has a layered first crystal phase having a crystal structure selected from the tetragonal structure, the rhombohedral structure, the pseudocubic structure and the monoclinic structure, a layered second crystal phase having a crystal structure different from the crystal structure of said first crystal phase and a boundary layer arranged between said first crystal phase and said second crystal phase with a crystal structure gradually changing in a width direction of layer.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a piezoelectric substrate, a piezoelectric element and a liquid discharge head to be used for a liquid discharge apparatus and also to methods of manufacturing the same. More particularly, the present invention relates to a high density piezoelectric element having a large area and a liquid discharge head using such an element. [0003] 2. Description of the Related Art [0004] There is an increasing demand for long printing heads to be used in ink jet printers in order to improve the resolution and the printing speed of such printers. For this reason, there is a demand for micronized multi-nozzle head structures. Then, piezoelectric elements for discharging liquid are required to be downsized in order to micronize liquid discharge heads. Then, piezoelectric substrates showing a high piezoelectric constant are required in order not to reduce the drive power if liquid discharge heads are...

AI Technical Summary

Benefits of technology

[0011] In view of the above identified circumstances, it is therefore an object of the present invention to provide a piezoelectric substrate that shows a controlled crystallinity and an enhanced level of orientation to realize excellent piezoelectric characteristics and produces an enhanced level of adhesiveness between the piezoelectric substrate and an electrode to make itself highly durable and capable of suppressing any possible film exfoliation as well as a piezoelectric element, a liquid discharge head and a liquid discharge apparatus realized by using such a piezoelectric substrate.

[0013] Still another object of the present invention is to provide a method of manufacturing a piezoelectric substrate that utilizes micro-processing techniques available in the field of semiconductor processes and a highly reliable liquid discharge head having densely arranged discharge ports prepared by means of such a method.

[0016] Thus, a piezoelectric substrate according to the present invention is highly durable and capable of suppressing any possible film exfoliation and produces an enhanced level of adhesiveness between the piezoelectric substrate and an underlying layer, showing a controlled crystallinity and an enhanced level of orientation to realize excellent piezoelectric characteristics. Additionally, a piezoelectric substrate according to the invention shows piezoelectric characteristics that do not degrade by the temperature change in the operation environment. Thus, a piezoelectric substrate according to the present invention shows excellent piezoelectric characteristics when it is used in a high density piezoelectric element and a liquid discharge head.

[0017] A method of manufacturing a piezoelectric substrate can manufacture a highly reliable piezoelectric substrate by utilizing micro-processing techniques available in the field of semiconductor processes that leads to a method of manufacturing a high density piezoelectric element and a method of manufacturing a highly reliable liquid discharge head.

Problems solved by technology

However, it is difficult to produce PZT type oxide films with a thickness of not greater than 10 μm by means of the method disclosed in Japanese Patent Application Laid-open No.

Additionally, since such green sheets are sintered at a temperature level not lower than 1,000° C., there arises a problem that the piezoelectric films shrink to 70% of the original size.

Then, it is difficult to align a piezoelectric film and a structure such as an ink chamber with an accuracy level of several microns.

Thus, no satisfactory micro piezoelectric elements have been available to date.

Furthermore, the influence of the crystal grain boundaries becomes unnegligible as ceramic piezoelectric films formed by sintering green sheets show a reduced thickness to consequently make it impossible to realize good piezoelectric characteristics.

As a result, there arises a problem of being unable to obtain piezoelectric characteristics that are satisfactory for causing a piezoelectric film to operate for discharging recording liquid if the piezoelectric film is prepared by sintering a green sheet to a thickness not greater than 10 μm.

However, since the piezoelectric film prepared by means of any of such methods shows a high density to by turn give rise to very large in-plane stress and make the piezoelectric film poorly adhesive to the underlying layer, which is a lower electrode.

However, a piezoelectric film prepared by any of the above-cited methods cannot be feasibly used as piezoelectric element for ink jet recording.

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