Method of fabricating a liquid-jet head

A liquid-jet head effective in prevention of imperfect eject such as occlusion of a nozzle, a method of fabricating the liquid-jet head, and a liquid-jet apparatus are provided. In a liquid-jet head having a passage-forming substrate on which a pressure-generating chamber communicating with a nozzle orifice is formed, a plurality of piezoelectric elements provided on one side of the passage-forming substrate via a vibration plate, each of the piezoelectric elements comprising a lower electrode, a piezoelectric layer and an upper electrode, the passage-forming substrate is provided with a communicating path communicating with one end in a longitudinal direction of the pressure-generating chamber so as to penetrate the passage-forming substrate. In addition, a penetrated portion for supplying a liquid to the communicating path is formed in a region of the vibration plate opposite to the communicating path by laser processing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to liquid-jet heads for ejecting, methods of fabricating the same and liquid-jet apparatuses. More specifically, the present invention relates to an ink-jet recording head for ejecting ink droplets out of nozzle orifices by applying pressure to ink supplied to pressure-generating chambers communicating with the nozzle orifices for ejecting the ink droplets by use of piezoelectric elements, a method of fabricating the same and an ink-jet recording apparatus.

2. Description of the Prior Art

Typical ink-jet recording heads include vibration plates, which constitute part of pressure-generating chambers communicating with nozzle orifices for ejecting ink droplets. Such ink-jet recording heads eject ink droplets out of the nozzle orifices by deforming the vibration plates with piezoelectric elements and thereby applying pressure to the ink in the pressure-generating chambers. There are two types of the ink-jet recording heads currently put into practical use; one uses a piezoelectric actuator of a longitudinal vibration mode, which expands and contracts in an axial direction of the piezoelectric element, and the other uses a piezoelectric actuator of a flexural vibration mode.

The former type effectuates variation of volumes of the pressure-generating chambers by allowing end faces of the piezoelectric elements to abut on the vibration plates. Accordingly, it is possible to fabricate a head suitable for high-density printing. However, the former type has a problem of complicated fabrication process, because the fabrication process includes a difficult step of sectioning the piezoelectric elements into comb shapes so as to align with arrangement pitches of the nozzle orifices, and an operation for positioning and fixing the sectioned piezoelectric elements to the pressure-generating chambers.

On the contrary, the latter type effectuates formation of the piezoelectric elements on the vibration plates by a relatively simple step of attaching a green sheet of a piezoelectric material in line with shapes of the pressure-generating chambers and then baking the green sheet. However, the latter type has a problem of difficulty in high-density arrangement, because a certain area is required for utilizing flexural vibration.

Meanwhile, in order to solve the inconvenience of the recording head of the latter type, Japanese Laid-Open No. 5(1993)-286131 discloses a recording head, in which a piezoelectric material layer is formed uniformly on an entire surface of a vibration plate by use of a film forming technology, and piezoelectric elements are independently formed for respective pressure-generating chambers by sectioning the piezoelectric material layer into shapes corresponding to the pressure-generating chambers by use of a lithography process.

Moreover, such an ink-jet recording head is provided with a reservoir as a common ink chamber to the respective pressure-generating chambers, whereby the ink is supplied from the reservoir to the respective pressure-generating chambers.

Such a reservoir has been conventionally formed on a passage-forming substrate, where the pressure-generating chambers are formed, on an opposite side to the piezoelectric elements, by means of laminating a plurality of substrates. However, there has been a problem of increases in material costs and assembly costs. In addition, there has been a problem of difficulty in downsizing the head. In order to solve the foregoing problems, a structure is proposed in which a reservoir is provided on the same side of a passage-forming substrate where piezoelectric elements are formed and the reservoir communicates with pressure-generating chambers via penetrated portions formed on vibration plates.

However, in the above-described ink-jet recording head, the penetrated portions are formed by mechanically processing the vibration plates. Accordingly, there is a problem that cracks or the like are generated around the penetrated portions. Moreover, there is also a problem that fragments may fall from a portion of the vibration plate where cracks are generated if ink is filled in and ejected in the state where the cracks are generated, whereby the fragments may occlude a nozzle orifice and may cause imperfect.

Note that the foregoing problems are not limited to ink-jet recording heads for ejecting ink, but are also applicable naturally to methods of fabricating other liquid-jet heads for ejecting liquids other than ink.

SUMMARY OF THE INVENTION

In consideration of the foregoing circumstances, it is an object of the present invention to provide a liquid-jet head which prevents imperfect eject such as occlusion of a nozzle, a method of fabricating the liquid-jet head and a liquid-jet apparatus.

To solve the foregoing problems, a first aspect of the present invention is a liquid-jet head having a passage-forming substrate on which a pressure-generating chamber communicating with a nozzle orifice is formed, a plurality of piezoelectric elements provided on one side of the passage-forming substrate via a vibration plate, each of the piezoelectric elements comprising a lower electrode, a piezoelectric layer and an upper electrode. Here, the passage-forming substrate is provided with a communicating path communicating with one end in a longitudinal direction of the pressure-generating chamber so as to penetrate the passage-forming substrate, and a penetrated portion for supplying a liquid to the communicating path is formed in a region of the vibration plate opposite to the communicating path by laser processing.

According to the first aspect, since the penetrated portion is formed by laser processing, cracks and the like are not generated around the penetrated portion. Therefore, it is possible to prevent occurrence of imperfect eject such as occlusion of a nozzle, attributable to a fragment of the vibration plate being mixed into the liquid.

A second aspect of the present invention is the liquid-jet head according to the first aspect, in which dross in an amount within one-fourth of a diameter of the nozzle orifice is adhered to a peripheral portion of the penetrated portion.

According to the second aspect, even if the dross falls off and is mixed into the liquid, the dross is d out of the nozzle orifice together with the liquid. Accordingly, occurrence of occlusion of the nozzle is avoided.

A third aspect of the present invention is the liquid-jet head according to any one of the first and the second aspects, in which the penetrated portion is at least formed into any of a size as large as an open region of the communicating path on the vibration plate side and a size smaller than the open region.

According to the third aspect, the passage-forming substrate and the like are not affected upon formation of the penetrated portion by laser processing.

A fourth aspect of the present invention is the liquid-jet head according to the third aspect, in which the penetrated portion is formed into a shape along an open edge of the communicating path.

According to the fourth aspect, it is possible to form the penetrated portion having the shape along the open edge of the communicating path by means of irradiating a laser beam along the open edge of the communicating path.

A fifth aspect of the present invention is the liquid-jet head according to the third aspect, in which the penetrated portion is composed of a plurality of penetrated holes provided within the open region of the communicating path.

According to the fifth aspect, it is easily possible to form the penetrated portion by laser processing, and it is also possible to prevent deformation of the passage-forming substrate owing to heat.

A sixth aspect of the present invention is the liquid-jet head according to any one of the first to fifth aspects, in which a reservoir-forming plate including a reservoir portion communicating with the communicating path via the penetrated portion is bonded to the passage-forming substrate on a side where the piezoelectric element is provided.

According to the sixth aspect, the reservoir is constituted is the communicating path and the reservoir portion communicating with each other via the penetrated portion. Moreover, it is possible to avoid any fragments from the vibration plate being mixed into the liquid in the reservoir.

A seventh aspect of the present invention is a liquid-jet apparatus including the liquid-jet head according to any one of the first to the sixth aspects.

According to the seventh aspect, it is possible to realize an ink-jet recording apparatus capable of preventing imperfect eject and thereby improved in reliability.

An eighth aspect of the present invention is a method of fabricating a liquid-jet head having a passage-forming substrate on which a pressure-generating chamber communicating with a nozzle orifice is formed, a plurality of piezoelectric elements provided on one side of the passage-forming substrate via a vibration plate, each of the piezoelectric elements comprising a lower electrode, a piezoelectric layer and an upper electrode. Here, the method includes the steps of forming the vibration plate and the piezoelectric element on one side of the passage-forming substrate, forming the pressure-generating chamber by patterning from another side of the passage-forming substrate and forming a communicating portion to communicate with one end in a longitudinal direction of the pressure-generating chamber, and forming a penetrated portion for supplying a liquid to the communicating path in a region of the vibration plate opposite to the communicating path by laser processing.

According to the eighth aspect, since the penetrated portion is formed by laser processing, cracks and the like are not generated around the penetrated portion.

A ninth aspect of the present invention is the method of fabricating a liquid-jet head according to the eighth aspect, in which a laser beam is irradiated on the vibration plate in the step of forming a penetrated portion to effectuate processing such that dross in an amount within one-fourth of a diameter of the nozzle orifice is adhered.

According to the ninth aspect, even if the dross adhered to the vicinity of an opening of the penetrated portion falls off and is mixed into the liquid, the dross is ejected out of the nozzle orifice together with the liquid. Accordingly, occurrence of occlusion of the nozzle is avoided.

A tenth aspect of the present invention is the method of fabricating a liquid-jet head according to any one of the eighth and the ninth aspects, in which a laser beam with a fundamental wavelength oscillated by a Q-switched YAG laser oscillator is irradiated on the vibration plate in the step of forming a penetrated portion.

According to the tenth aspect, the penetrated portion is formed by locally heating the vibration plate. Therefore, it is possible to form the penetrated portion favorably without affecting the periphery thereof. In particular, since the penetrated portion can be formed by a laser beam with a relatively low output level, the passage-forming substrate in the vicinity thereof is prevented from deformation attributable to processing or heat.

An eleventh aspect of the present invention is the method of fabricating a liquid-jet head according to any one of the eighth and the ninth aspects, in which a laser beam with a higher harmonic wavelength oscillated by a Q-switched YAG laser oscillator is irradiated on the vibration plate in the step of forming a penetrated portion.

According to the eleventh aspect, the penetrated portion is formed by locally heating the vibration plate. Therefore, it is possible to form the penetrated portion favorably without affecting the periphery thereof.

A twelfth aspect of the present invention is the method of fabricating a liquid-jet head according to any one of the eighth and the ninth aspects, in which a laser beam with a second harmonic wavelength oscillated by a Q-switched YAG laser oscillator is irradiated on the vibration plate in the step of forming a penetrated portion.

According to the twelfth aspect, the penetrated portion is formed by locally heating the vibration plate. Therefore, it is possible to form the penetrated portion favorably without affecting the periphery thereof.

A thirteenth aspect of the present invention is the method of fabricating a liquid-jet head according to any one of the eighth to the twelfth aspects, in which the laser processing is performed underwater.

According to the thirteenth aspect, fragments generated upon formation of the penetrated portion are rinsed off with water. Therefore, it is possible to prevent the fragments from remaining and being mixed into the liquid.

A fourteenth aspect of the present invention is the method of fabricating a liquid-jet head according to any one of the eighth to the thirteenth aspects, in which the laser beam is irradiated on the vibration plate in a region corresponding to an open edge of the communicating portion and the laser beam is scanned along the open edge of the communicating portion in the step of forming a penetrated path.

According to the fourteenth aspect, the penetrated portion is formed by locally heating the vibration plate. Therefore, it is possible to form the penetrated portion favorably without affecting the periphery thereof.

A fifteenth aspect of the present invention is the method of a liquid-jet head according to any one of the eighth to the thirteenth aspects, in which a plurality of penetrated holes are formed on at least the vibration plate in a region opposite to the communicating path in the step of forming a penetrated portion.

According to the fifteenth aspect, it is possible to form the penetrated portion favorably without affecting the periphery thereof.

A sixteenth aspect of the present invention is the method of fabricating a liquid-jet head according to any one of the eighth to the fifteenth aspects. Here, before the step of forming the penetrated portion on the vibration plate the method includes the step of bonding a reservoir-forming plate, which has a reservoir portion communicating with the communicating path via the pierced hole, to the passage-forming substrate on a side where the piezoelectric element is formed.

According to the sixteenth aspect, rigidity of the passage-forming substrate is increased owing to the reservoir-forming plate. Therefore, it is possible to form the pressure-generating chamber and the communicating path favorably by etching and to form the penetrated portion favorably.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, the present invention will be described in detail based on certain preferred embodiments.

FIG. 1is an exploded perspective view showing an ink-jet recording head according to embodiment 1 of the present invention.FIGS. 2A and 2Bare a plan view and a cross-sectional view relevant toFIG. 1, respectively.

As shown in the drawings, a passage-forming substrate10is made of a single-crystal silicon substrate having plane orientation of (110) in this embodiment. On this passage-forming substrate10, pressure-generating chambers12partitioned by a plurality of partition walls11are arranged in parallel along the width direction thereof. The pressure-generating chambers12are formed by anisotropic etching from one plane of the passage-forming substrate10. Moreover, outside one end in a longitudinal direction of each pressure-generating chamber12, a communicating path13is formed, which constitutes part of a reservoir110as a common ink chamber to the respective pressure-generating chambers12by communicating with a reservoir portion of a reservoir-forming plate to be described later. The communicating path13communicates with one end in the longitudinal direction of respective pressure-generating chambers12via each ink supply path14.

Meanwhile, on the other plane of the passage-forming substrate10, an elastic film50in a thickness from 1 to 2 μm is formed, which is made of silicon oxide. (SiO2), for example.

Here, the anisotropic etching is performed by use of a difference in etching rates on the single-crystal silicon substrate. For example, if the single-crystal silicon substrate is soaked into an alkaline solution such as KOH in this embodiment, then the single-crystal silicon substrate is gradually corroded away, whereby a first (111) plane perpendicular to a (110) plane, and a second (111) plane at about a 70-degree angle with the first (111) plane and about a 35-degree angle with the (110) plane emerge. The anisotropic etching is performed by use of the disposition that the etching rate of the (111) plane is about 1/180 of the etching rate of the (110) plane. By use of the anisotropic etching as described above, it is possible to perform high-precision processing based on depth processing in a parallelogram shape defined by two of the first (111) planes and two of the inclined second (111) planes. In this way, it is possible to arrange the pressure-generating chambers12in high density.

In this embodiment, long edges of the respective pressure-generating chambers12are formed by the first (111) planes and short edges thereof are formed by the second (111) planes. Moreover, the pressure-generating chambers12and the communicating path13are formed by etching so as to almost penetrate the passage-forming substrate10until reaching the elastic film50. Here, the elastic film50is exposed to an extremely small degree of erode by the alkaline solution for etching the single-crystal silicon substrate.

Moreover, each ink supply path14communicating with one end of each pressure-generating chamber12is formed shallower than the pressure-generating chamber12, whereby resistance on a passage of the ink flowing into the pressure-generating chamber12is maintained at a constant level. In other words, the ink supply paths14are formed by etching the single-crystal silicon substrate halfway in the thickness direction (half-etching). Note that the half-etching is performed by adjusting etching time.

Regarding the thickness of the passage-forming substrate10, an optimum thickness is selected in accordance with arranging density of the pressure-generating chambers12. In the case of arranging the pressure-generating chambers12by 180 pieces per inch (180 dpi) or thereabout, for example, the thickness of the passage-forming substrate10is preferably set in a range from about 180 to 280 μm, or more preferably at about 220 μm. In the case of arranging the pressure-generating chambers12in relatively high density by 360 dpi or thereabout, for example, then the thickness of the passage-forming substrate10is preferably set within 100 μm. This is because the partition walls between adjacent pressure-generating chambers can maintain sufficient rigidity while increasing the arranging density.

A nozzle plate20is fixed to an open side of the passage-forming substrate10with an adhesive, a thermo-bonding film, or the like. Here, the nozzle plate20is provided with nozzle orifices21drilled thereon. The nozzle orifices21communicate with the respective pressure-generating chambers12on opposite sides to the ink supply paths14. The nozzle plate20is made of glass ceramics, stainless steel or the like, which has a thickness in a range from 0.1 to 1 mm and a coefficient of linear expansion in a range from 2.5 to 4.5×10−6/° C. at a temperature of 300° C. or lower, for example. The nozzle plate20covers the entire surface of one plane of the passage-forming substrate10with one plane thereof, whereby the nozzle plate20also functions as a reinforcing plate for protecting the single-crystal silicon substrate against shock or external force. Meanwhile, it is also possible to form the nozzle plate20by use of a material having a coefficient of thermal expansion almost as the same as that of the passage-forming substrate10. In this case, degrees of deformation of the passage-forming substrate10and the nozzle plate20owing to heat become almost equivalent to each other. Accordingly, it is possible to bond the both members easily by use of a thermosetting adhesive or the like.

Here, sizes of the nozzle orifices21and sizes of the pressure-generating chambers12are optimized in accordance with an amount of ink droplets to be ejected, a eject speed, a eject frequency and the like. For example, in the case of recording 360 dots of ink droplets per inch, the nozzle orifices21need to be formed accurately so as to have diameters of several ten micrometers.

Meanwhile, a lower electrode film60having a thickness of about 0.2 μm, for example, a piezoelectric layer70having a thickness in a range from about 0.5 to 3 μm, for example, and an upper electrode film80having a thickness of about 0.1 μm, for example, are formed on the elastic film50provided on the passage-forming substrate10by lamination in accordance with a process to be described later, whereby piezoelectric elements300are constituted accordingly. Here, the piezoelectric elements300refer to portions including the lower electrode film60, the piezoelectric layer70and the upper electrode film80. In general, each of the piezoelectric elements300is constituted by setting one of the electrodes thereof as a common electrode, while patterning the other electrode and the piezoelectric layer70depending on each pressure-generating chamber12. Moreover, each portion composed of one of the electrodes and the piezoelectric layer70which are patterned, in which piezoelectric distortion is caused upon application of electric voltage between the both electrodes, is hereinafter referred to as a piezoelectric active portion320. In this embodiment, the lower electrode film60is defined as the common electrode of each piezoelectric element300and the upper electrode film80is defined as an individual electrode of the piezoelectric element300. However, it is by all means possible to invert such definitions due to reasons attributable to drive circuits or wiring designs. In any case, each piezoelectric active portion will be formed on each pressure-generating chamber. Furthermore, the piezoelectric element300and a vibration plate, which is displaced when the piezoelectric element300is driven, are hereinafter collectively referred to as a piezoelectric actuator.

Moreover, the reservoir-forming plate30including the reservoir portion31which constitutes at least part of the reservoir110is bonded onto the passage-forming substrate10where the piezoelectric elements are formed. In this embodiment, the reservoir portion31penetrates the reservoir-forming plate30in the thickness direction thereof and is formed across the pressure-generating chambers12in the width direction thereof. In addition, the reservoir portion31is formed such that at least an open region of the reservoir portion31on the passage-forming substrate10side is larger than an open region of the communicating path13on the reservoir-forming plate30side. Furthermore, the reservoir portion31communicates with the communicating path13of the passage-forming substrate10via a penetrated portion100which penetrates the elastic film50and the lower electrode film60, thus constituting the reservoir110as a common ink chamber to the respective pressure-generating chambers12.

As for the reservoir-forming plate30, it is preferred to use a material having almost the same coefficient of thermal expansion as that of the passage-forming substrate10such as glass and a ceramic material. In this embodiment, for example, the reservoir-forming plate30is made of a single-crystal silicon substrate having a thickness of about 400 μm, which is the same material as the passage-forming substrate10.

Here, the penetrated portion100which connects between the communicating path13and the reservoir portion31is formed in a region of the elastic film50and the lower electrode film60opposite to the communicating path13; more specifically, inside the open region of the communicating path13on the reservoir-forming plate30side. For example, the penetrated portion100of this embodiment is composed of a pierced hole51, which is almost as large as the open region of the communicating path13on the reservoir-forming plate30side.

As will be described later in detail, the penetrated portion100is formed by laser processing of the vibration plate (the elastic film50and the lower electrode film60). In this way, the penetrated portion100is favorably formed without generating cracks or the like in the periphery thereof. As a result, fragments of the elastic film50or the lower electrode film60are not scattered and mixed into the ink. In this way, it is possible to prevent occurrence of imperfect ink eject attributable to occlusion of the nozzle orifice21by the fragments.

A compliance substrate40composed of a sealing film41and a fixing plate42is bonded to the reservoir-forming plate30. Here, the sealing film41is made of a material having low rigidity and high flexibility (such as a polyphenylene sulfide (PPS) film having a thickness of 6 μm). One side of the reservoir portion31is sealed by this sealing film41. Meanwhile, the fixing plate42is made of a hard material of metal or the like (such as stainless steel (SUS) having a thickness of 30 μm). Moreover, a region of the fixing plate42opposite to the reservoir110is completely removed in the thickness direction so as to constitute an opening portion43. Accordingly, one side of the reservoir110is just sealed by the flexible sealing film41and thereby constitutes a flexible portion32, which is deformable upon variations of inner pressure.

Moreover, an ink introducing port35for supplying the ink to the reservoir110is formed on the compliance substrate40in a position outside almost the central portion in the longitudinal direction of the reservoir110. In addition, an ink introducing path36is provided in the reservoir-forming plate30so as to connect between the ink introducing port35and a sidewall of the reservoir110.

Meanwhile, in a region of the reservoir-forming plate30opposite to the piezoelectric elements300, a piezoelectric element holding portion33is provided so as to secure a sufficient space not to interfere with motion of the piezoelectric elements300and so as to hermetically seal the space. Here, at least the piezoelectric active portions320of the piezoelectric elements300are hermetically sealed inside the piezoelectric element holding portion33, whereby the piezoelectric elements300are prevented from destruction attributable to external environment such as moisture in the atmosphere.

The ink-jet recording head constituted as described above intakes the ink through the ink introducing port35connected to unillustrated external ink supply means, whereby the ink is filled throughout the inside from the reservoir110to the nozzle orifices21. Next, electric voltage is applied between the upper electrode film80and the lower electrode film60in accordance with a recording signal from an unillustrated external drive circuit, whereby the elastic film50, the lower electrode film60and the piezoelectric layer70are subjected to flexure deformation. In this way, pressure inside the pressure-generating chamber12is increased and the ink droplets are thereby ejected out of the relevant nozzle orifice21.

Now, description will be made regarding a method of fabricating the above-described ink-jet recording head with reference toFIG. 3Ato FIG.4D. Note thatFIG. 3AtoFIG. 4Dare cross-sectional views taken along the longitudinal direction of the pressure-generating chamber12.

First, as shown inFIG. 3A, the elastic film50is formed. To be more precise, a zirconium layer is formed on the passage-forming substrate10and then subjected to thermal oxidation in a diffusion furnace at a temperature in a range from 500° C. to 1200° C., thus forming the elastic film50made of zirconium oxide.

Next, as shown inFIG. 3B, the lower electrode film60made of platinum, for example, is formed on the entire surface of the elastic film50and then patterned into a given shape.

Next, as shown inFIG. 3C, the piezoelectric layer70made of lead zirconate titanate (PZT), for example, and the upper electrode film80made of a variety of metal including aluminum, gold, nickel, platinum and the like, or made of a conductive oxide and the like, are deposited serially and then patterned simultaneously to form the piezoelectric elements300.

Subsequently, as shown inFIG. 3D, a lead electrode90made of gold (Au), for example, is formed on the entire surface of the passage-forming substrate10and then patterned in line with the respective piezoelectric elements300.

The foregoing steps collectively constitute a film-forming process. Now, as shown inFIG. 4A, the reservoir-forming plate30where the reservoir portion31, the piezoelectric element holding portion33and the like are formed is bonded to the passage-forming substrate10on the side where the piezoelectric elements300are formed, by use of an adhesive or the like.

Subsequently, as previously described, the passage-forming substrate10made of the single-crystal silicon substrate is subjected to the anisotropic etching until reaching the elastic film50, whereby the pressure-generating chambers12, the communicating path13and the ink supply paths14are simultaneously formed as shown in FIG.4B.

Next, as shown inFIG. 4C, the elastic film50and the lower electrode film60in the region opposite to the communicating path13are removed by laser-processing, whereby the penetrated portion100is formed.

To be more precise, a laser beam120is focused and irradiated from the communicating path13side of the passage-forming substrate10onto the elastic film50in the region corresponding to the open edge of the communicating path13on the reservoir side, and then the laser beam120is scanned along the open edge of the communicating path13. In this way, the elastic film50and the lower electrode film60are locally subjected to thermal processing and thereby cut away along the open edge of the communicating path13. As a consequence, the elastic film50and the lower electrode film60in the open region of the communicating path13are removed together as shown in FIG.4D and the penetrated portion100is formed. In short, the penetrated portion100is formed virtually as the same size as the open region of the communicating path13on the vibration plate side.

Here, it is preferred to use a laser beam oscillated by a Q-switched YAG laser oscillator for formation of the penetrated portion100, i.e. removal of the elastic film50and the lower electrode film60. For example, in this embodiment, a laser beam having a fundamental wavelength (1064 nm) is focused and irradiated on the surface of the elastic film50, and the penetrated portion100is formed by cutting the elastic film50and the lower electrode film60away.

For example, in this embodiment, the laser beam having the fundamental wavelength is oscillated at an output level of about 10 mW (a repetition frequency at 1 kHz) by the Q-switched YAG laser oscillator and is irradiated from the elastic film50side onto the vibration plate so as to form the penetrated portion100.

In this way, it is possible to prevent the fragments of the elastic film50or the lower electrode film60from scattering in the event of forming the penetrated portion100, and it is also possible to avoid occurrence of imperfect eject such as occlusion of the nozzle by the fragments.

Moreover, since the Q-switched YAG laser oscillator is used for forming the penetrated portion100, it is possible to process with a laser beam at a relatively lower power level. Specifically, since the penetrated portion100is formed in this embodiment by use of the laser beam having the fundamental wavelength, the passage-forming substrate10and the like in the vicinity of the penetrated portion100are prevented from being processed (heated) by the laser beam. Accordingly, it is possible to cut only the elastic film50and the lower electrode film60favorably.

Here, if a focus point P1of the laser beam120is located in a position shifted from the vibration plate as shown inFIG. 5, for example, then the laser beam120will be also irradiated on the passage-forming substrate10as well as the elastic film50. Moreover, the communicating path13, for example, is formed by subjecting the passage-forming substrate10to the anisotropic etching. Therefore, the side face of the communicating path13includes portions composed of inclined planes13aas shown inFIG. 4C, which are inclined with respect to the surface of the passage-forming substrate10. Moreover, the side face of the communicating path13also includes portions composed of perpendicular planes13b, which are almost orthogonal with respect to the surface of the passage-forming substrate10. Accordingly, although the laser beam120may not be irradiated on the passage-forming substrate10in the portion where the side face of the communicating path13is composed of the inclined plane13a, the laser beam120is surely irradiated on the passage-forming substrate10in the portion where the side face of the communicating path13is composed of the perpendicular plane13b(see FIG.6).

Nevertheless, in this embodiment, the passage-forming substrate10is made of the single-crystal silicon substrate having a relatively low index of laser-beam absorption, and the elastic film50and the lower electrode film60are cut away by irradiating the laser beam of the fundamental wavelength at a relatively low output level. Accordingly, if the laser beam120is irradiated on the passage-forming substrate10, it is possible to cut only the elastic film50and the lower electrode film60away favorably without processing (heating) the passage-forming substrate10.

Meanwhile, in the event of forming the penetrated portion100by laser processing as described above, dross is adhered to a surface of the vibration plate opposite to the side where the laser beam120is irradiated, i.e. to a surface of the lower electrode film60in the periphery of the penetrated portion100. If the dross falls off and is mixed into the ink, there is a risk of causing imperfect eject such as occlusion of the nozzle by the dross.

Nevertheless, if the penetrated portion100is formed by cutting the elastic film50and the lower electrode film60away along the open edge of the communicating path13as described in this embodiment, in other words, if the elastic film50and the lower electrode film60are cut away and removed by means of locally irradiating the laser beam120only onto the region corresponding to the open edge of the communicating path13, the size of the dross to be adhered to the periphery of the penetrated portion100is limited to one-fourth or less of a diameter of the nozzle orifice21.

Therefore, if the dross of that size falls off and is mixed into the ink, this dross will be ejected from the nozzle orifice21together with the ink. Accordingly, occlusion of the nozzle by the dross does not occur, and ink eject performance can be thereby maintained favorably.

Note that the penetrated portion100is formed by irradiating the laser beam having the fundamental wavelength onto the elastic film50and the lower electrode film60in this embodiment. However, the penetrated portion100may be also formed by irradiating a laser beam having a higher harmonic wavelength oscillated from the Q-switched YAG laser oscillator, for example, by irradiating a second harmonic laser beam (having a wavelength of 532 nm). If the penetrated portion100is formed by such a laser beam having a relatively shorter wavelength, the size of the dross will be reduced even smaller. Therefore, it is possible to prevent occurrence of occlusion of the nozzle or the like even more surely.

Moreover, in this embodiment, the penetrated portion100is formed by irradiating the laser beam from the elastic film50side onto the vibration plate because the reservoir-forming plate30has a thickness several times thicker than the passage-forming substrate10. However, the direction of irradiation of the laser beam is not particularly limited thereto. It is by all means possible to form the penetrated portion100by irradiating the laser beam from the lower electrode film60side onto the vibration plate as shown in FIG.7. As previously mentioned, the lower electrode film60tends to absorb the laser beam relatively easily because the lower electrode film60is made of metal such as platinum. Therefore, the mode of irradiating the laser beam from the lower electrode film60side onto the vibration plate offers an advantage of enhancement in process efficiency.

Furthermore, although the laser processing may take place in the atmosphere, it is preferred to dispose the workpiece fabricated in the foregoing steps underwater. In other words, it is preferred to form the penetrated portion100by means of irradiating the laser beam onto the elastic film50and the lower electrode film60underwater. In this way, it is possible to surely prevent the fragments of the elastic film50or the lower electrode film60from being mixed into the ink.

As described above, the present invention adopts the mode of forming the penetrate portion100by use of the laser processing. Accordingly, cracks and the like are not generated on the elastic film50and the lower electrode film60around the penetrated portion100. Therefore, when the ink is filled into the reservoir110, the elastic film50and the lower electrode film60around the penetrated portion100do not fall off largely owing to the cracks. Accordingly, such a large fragment will not be mixed into the ink. As a consequence, it is possible to prevent imperfect eject such as occlusion of the nozzle, and to achieve the ink-jet recording head with improved reliability.

Moreover, since the penetrated portion100is formed by the laser processing, i.e. non-contact processing, it is possible to form the penetrated portion100easily and favorably regardless of in an underwater condition or an atmospheric condition, without requiring special treatment.

After the penetrated portion100is formed as described above, the compliance substrate40is bonded onto the reservoir-forming plate30and the nozzle plate20is bonded to and integrated with the passage-forming substrate10on the opposite side to the reservoir-forming plate30. In this way, the ink-jet recording head is fabricated.

FIG. 8is a plan view of an ink-jet recording head according to embodiment 2.

Embodiment 1 describes the example that the penetrated portion100is composed of the pierced hole51almost as large as the open region of the communicating path13on the reservoir-forming plate30side. However, it is just satisfactory as far as the penetrated portion100is formed inside the open region of the communicating path13.

This embodiment shows an example that a penetrated portion is composed of penetrated holes smaller in size than an open region of a communicating path. To be more precise, as shown inFIG. 8, a penetrated portion100A is composed of a plurality of penetrated holes51A formed on a vibration plate in a region corresponding to an open region of a communicating path13. Here, other elements are similar to those in embodiment 1.

As similar to embodiment 1, the plurality of penetrated holes51A can be formed by cutting an elastic film50and a lower electrode film60by scanning with a laser beam120so as to remove the elastic film50and the lower electrode film60together regarding portions to form the respective penetrated holes51A.

If the sizes of the penetrated holes51A are relatively small, then it is also possible to irradiate the laser beam onto the elastic film50and the lower electrode film60in the positions to form the respective penetrated holes51A such that the relevant portions of the elastic film50and the lower electrode film60are removed by thermal processing.

Similar effects to embodiment 1 can be obtained if the penetrated portion100A is composed of the plurality of penetrated holes51A as described above.

Although the present invention has been described with reference to certain embodiments, it is to be noted that the present invention is not limited to the above-described embodiments.

For example, although the penetrated portion100is formed after bonding the reservoir-forming plate30to the passage-forming substrate10in the above-described embodiments, it is by all means possible to form the penetrated portion100before bonding the reservoir-forming plate30to the passage-forming substrate10.

Moreover, in the above-described embodiment 1, the penetrated portion100is formed by scanning along the open edge of the communicating path13with the laser beam to cut the elastic film50and the lower electrode film60away. However, without limitation to the foregoing, it is by all means possible to irradiate the laser beam onto the elastic film50and the lower electrode film60within the open region of the communicating path13so as to remove the elastic film50and the lower electrode film60away by thermal processing. When the elastic film50and the lower electrode film60are removed by thermal processing as described above, for example, it is also possible to leave the piezoelectric layer70and the upper electrode film80for constituting the piezoelectric element300on the lower electrode film60in the region opposite to the communicating path13as shown inFIG. 9A, and to form the penetrated portion100by irradiating the laser beam120from above the upper electrode film80. Rigidity of the films formed in the region opposite to the communicating path13is enhanced by means of leaving the piezoelectric layer70and the upper electrode film80in the region opposite to the communicating path13. Accordingly, it is possible to favorably form the penetrated portion100. Note that the piezoelectric layer70and the upper electrode film80in the region opposite to the communicating path13may still remain after formation of the penetrated portion100. However, in reality, the piezoelectric layer70and the upper electrode film80are substantially removed by irradiation of the laser beam120as shown in FIG.9B.

Moreover, in the above-described embodiments, the Q-switched YAG laser oscillator is used for forming the penetrated portion100, for example. However, without limitation to the foregoing, it is also possible to use a femtosecond laser oscillator, for example, which can oscillate laser beams smaller in pulse widths than the Q-switched YAG laser oscillator.

Moreover, in the above-described embodiments, the communicating path13is formed continuously over the regions corresponding to the plurality of the pressure-generating chambers12to communicate with the plurality of the pressure-generating chambers12via the respective ink supply paths14, for example. However, without limitation to the foregoing, it is also possible to form the communicating paths13independently for the respective pressure-generating chambers12, for example. In this case, it is preferred to provide the penetrated portions100independently for the respective communicating paths13as well.

Furthermore, the above-described embodiments have exemplified the ink-jet recording head of a thin-film type, which can be fabricated by applying film-forming and lithography processes. However, it is needless to say that the present invention is not limited to the foregoing. For example, the present invention is also applicable to ink-jet recording heads having various types of structures, such as an ink-jet recording head including pressure-generating chambers formed by laminating substrates, an ink-jet recording head including a piezoelectric layer formed by adhesion of a green sheet or by screen printing, and an ink-jet recording head including a piezoelectric layer formed by crystal growth owing to hydrothermal crystallization method or the like.

As described above, the present invention is applicable to various ink-jet recording heads having different structures unless such application goes against the spirit of the invention.

Meanwhile, the ink-jet recording head according to any of these embodiments constitutes part of a recording head unit which includes ink passages communicating with ink cartridges and the like, whereby the ink-jet recording head is installed in an ink-jet recording apparatus.FIG. 10is a schematic view showing one example of such an ink-jet recording apparatus.

As shown inFIG. 10, cartridges2A and2B severally constituting ink supplying means are disposed detachably on recording head units1A and1B severally provided with the ink-jet recording heads. A carriage3carrying the recording head units1A and1B is provided as movable along an axial direction on a carriage shaft5fitted to an apparatus body4. For example, the recording head units1A and1B are designed to eject a black ink composition and a color ink composition, respectively.

Moreover, driving power of a drive motor6is transferred to the carriage3through unillustrated gears and a timing belt7, whereby the carriage3carrying the recording head units1A and1B is moved along the carriage shaft5. Meanwhile, a platen8is provided on the apparatus body4along the carriage3. The platen8is made rotatable by driving power of an unillustrated paper-feeding motor. Moreover, a recording sheet S, which is a recording medium such as paper fed by a paper-feeding roller or the like, is conveyed on the platen8.

In the foregoing explanations, the ink-jet recording head for ejecting ink has been taken as an example of the liquid-jet head. However, it is to be understood that the present invention is generally applicable to wide ranges of liquid-jet heads and liquid-jet apparatuses.

Such applied liquid-jet heads may include, for example, a recording head for use in an image recording apparatus such as a printer, a color material-jet head for use in fabrication of a color filter of a liquid crystal display device and the like, an electrode material-jet head for use in formation of electrodes of an organic electroluminescent display device, a field emission display (FED) device and the like, and a bioorganic material-jet head for use in fabrication of a biochip.

As describe above, according to the present invention, the penetrated portion is formed on the vibration plate in the region opposite to the communicating path by laser processing. Accordingly, it is possible to form the penetrated portion favorably without generating cracks on the vibration plate. Therefore, it is possible to avoid imperfect eject such as occlusion of a nozzle by fragments of the vibration plate.