Liquid ejecting head and liquid ejecting apparatus

A liquid ejecting head including a first base member in which a plurality of pressure generating chambers communicating with nozzle openings and a series of partition walls are arranged in parallel, a second base member disposed on the first base member, a reservoir serving as a common liquid chamber for the pressure generating chambers, and an adhesive agent adhered to a first angular portion formed in an end portion of the partition walls near the reservoir which is adjacent to the second base member.

CROSS-REFERENCES AND RELATED APPLICATIONS

The entire disclosures of Japanese Patent Application No. 2008-323323, filed Dec. 19, 2008 is expressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to a liquid ejecting head and a liquid ejecting apparatus. More specifically, the present invention relates to an ink jet type recording head and ink jet type recording apparatus which discharges ink as liquid.

2. Related Art

One ink jet type recording head of a liquid ejecting head currently known in the art uses an actuator having a vibration-mode piezoelectric element. The piezoelectric elements vibrates a vibration plate disposed adjacent to a pressure generating chamber communicating with a nozzle opening causing pressure to be applied to the ink in the pressure generating chamber such that ink droplets are discharged from the nozzle opening.

The ink jet recording head includes a passage forming substrate communicating with the nozzle opening. The passage forming substrate has a plurality of pressure generating chambers which are arranged in parallel and are partitioned by partition walls, a piezoelectric element which is formed by stacking a lower electrode membrane, a piezoelectric layer, and an upper electrode membrane with an insulating membrane disposed between the piezoelectric element and the pressure generating chamber of the passage forming substrate. The insulating membrane functions as a vibration plate, while a reservoir forming substrate includes a reservoir portion which is adhered to the passage forming substrate serves as a common ink chamber of the pressure generating chamber. An example of such a configuration is shown in Japanese Patent Document JP-A-2007-26125.

An ink supply path for supplying ink in the reservoir portion to the respective pressure generating chamber is provided to the respective pressure generating chamber. The respective ink supply paths are formed by extending the partition walls disposed at both sides of width direction of the respective pressure generating chamber. Furthermore, an upper surface of each partition wall is adhered to a reservoir forming substrate with the vibration plate formed there between, and an under surface of each partition wall is adhered to a nozzle plate.

One problem with the ink jet type recording head according to this configuration, however, is that the difference in the linear expansion coefficient between the passage forming substrate and the nozzle plate causes bending stress over the whole passage forming substrate. This stress is particularly strong at one of the weakest areas of the passage forming substrate, near the end portion of the partition walls of the ink supply path. The stress may result in breaks and damaged recording heads.

Also, the bending stress that causes a surface of the nozzle plate to become concave, causing increased stress as the partition wall is pulled by the nozzle plate, and as a result, the vibration plate may become cracked and broken.

As mentioned above, the vicinities of end portions of the partition walls partitioning the pressure generating chambers are apt to be broken by the bending stress, so that the quality and performance of the ink jet recording head may be deteriorated. This difficulty exists not only in the ink jet type recording head discharging ink but also in other liquid ejecting heads discharging liquid other than ink.

BRIEF SUMMARY OF THE INVENTION

An advantage of an aspect of the invention is to provide a liquid ejecting head and a liquid ejecting apparatus with partition walls partitioning the pressure generating chambers and vibration plate which are more resistant.

A first aspect of the invention is a liquid ejecting head including a first base member including a plurality of pressure generating chambers communicating with respective nozzle openings from which liquid is ejected, and a plurality of parallel partition walls which partition the pressure generating chambers. The liquid ejecting head also includes a second base member disposed on one surface of the first base member, a reservoir serving as a common liquid chamber for the pressure generating chambers, and an adhesive agent adhered to a first angular portion formed in an end portion of the partition walls near the reservoir which is adjacent to the second base member.

One advantage of the first aspect of the invention is that the adhesive agent is provided to the first angular portion of the partition wall such that any stress applied to the first angular portion is relieved. Therefore, the adhesive agent is able to protect the front end portion of the partition wall, which are typically vulnerable to destruction caused by the stress. Consequently, though stress is applied to the front end portion of the partition wall, the stress is relieved to prevent the front end portion from being broken. Furthermore, the adhesive agent is also able to prevent cracks from being generated in the second base member, even though the partition wall and even the second base member are pulled by bending condition.

Another aspect of the invention us a liquid ejecting apparatus includes the liquid ejecting head described above. With the aspect, a liquid ejecting apparatus having an excellent durability can be provided.

A third aspect of the invention is a liquid ejecting head comprising a first base member including a plurality of pressure generating chambers communicating with respective nozzle openings from which liquid is ejected, a flow passage communicating with the pressure generating chambers, and a plurality of parallel partition walls which partition the pressure generating chambers and flow passage. The liquid ejecting head also includes a second base member disposed on one surface of the first base member, a reservoir serving as a common liquid chamber for the pressure generating chambers which communicates with the pressure generating chambers via the flow passage, and an adhesive agent adhered to a first angular portion formed in an end portion of the partition walls near the reservoir which is adjacent to the second base member and a second angular portion formed in the partition walls partitioning the flow passage which is adjacent to the second base member, wherein the first angular portion and second angular portion have groove portions formed therein which cause the adhesive agent to flow from the first angular portion to the second angular portion using capillary action.

One advantage of the third aspect of the invention is that the groove portions of the first and second angular portions assist in the distribution of the adhesive agent so as to simplify the manufacturing processes used to manufacture the liquid ejecting head.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the invention will be described in detail with reference to drawings.

First Embodiment

FIG. 1is an exploded perspective view showing a schematic structure of an ink jet recording head that is one example of a liquid ejecting head related to the embodiment of the invention,FIG. 2Ais a plan view ofFIG. 1,FIG. 2Bis a cross-sectional view taken along a line IIB-IIB of theFIG. 2A,FIG. 3is a cross-sectional view taken along line a III-III of theFIG. 2B,FIG. 4Ais a cross-sectional view taken along a line IVA-IVA of theFIG. 2A,FIG. 4Bis a cross-sectional view taken along a line IVB-IVB of theFIG. 2A.

As shown in the drawings, a passage forming substrate10that is an example of a first base member is made of a silicon single crystal substrate in which the crystals are oriented to a plane direction (110). An elastic membrane51formed of an oxide film is provided on one surface of the passage forming substrate10. The passage forming substrate10includes a plurality of parallel pressure generating chambers12partitioned by partition walls11which are arranged in a width direction. The upper surface of the pressure generating chambers12is provided by the elastic membrane51.

Communicating passages14and ink supply paths13which communicate with the respective pressure generating chambers12which are partitioned by the partition walls11are formed at longitudinal end portions of the respective pressure generating chambers12in the passage forming substrate10. A communicating portion15communicating with each of communicating passages14is formed adjacent to the communicating passages14. The communicating portion15communicates with a reservoir portion32of a reservoir forming substrate30, described more fully below, in order o form a reservoir100which serves as a common ink chamber for the pressure generating chambers12.

Here, the ink supply path13has a smaller cross sectional area than that of the pressure generating chamber12, which keeps constant flow resistance of ink between the pressure generating chamber12and the communicating portion15. In one embodiment, the ink supply paths13are formed by narrowing the width of the passage between the reservoir100and each pressure generating chamber12by extending one side of the partition wall11so that the pressure generating chamber12has a narrower width.

Although in this embodiment the ink supply path13is formed by narrowing the width of the passage from one side of the passage, it is also possible to form the ink supply path13by narrowing the width of the passage from both sides. Furthermore, the ink supply path13can be also formed by narrowing the passage from a thickness direction of the passage instead of by narrowing the width of the passage. Each communicating passage14is partitioned by the partition walls11and is formed by extending the partition walls11inwards towards the pressure generating chamber12so as to form a space between the ink supply path13and the communicating portion15.

In addition, even though the silicon single crystal substrate is used as a material for manufacturing the passage forming substrate10in the present embodiment, the material is not limited to the silicon single crystal substrate, and, for example, glass ceramics can be also used.

A nozzle plate20in which nozzle openings21are formed so as to communicate with the respective pressure generating chambers12is fixed to a passage surface of the passage forming substrate10by use of adhesive agent17. The nozzle plate20is formed of, for example, glass ceramics, silicon single crystal substrate, stainless steel.

Meanwhile, a piezoelectric elements300are provided on the passage surface of the passage forming substrate10with a vibration plate50formed there between.

The piezoelectric elements300and the vibration plate50which are driven to vibrate by the piezoelectric elements300are referred to collectively as an actuator. In the present embodiment, the elastic membrane51is provided on the passage forming substrate10as described above. An insulation membrane52is formed on the elastic membrane51. The insulation membrane52is formed of a material which is different from the elastic membrane51, such as, for example, an oxide film formed of titanium oxide (TiOx). The elastic membrane51and the insulating membrane52together constitute the vibration plate50. Also, the vibration plate50is integrally formed with the passage forming substrate10instead of adhesion by adhesive agent.

A partition wall11of a pressure generating chamber12includes a front end portion11awhose width becomes smaller on the side toward the reservoir100. The front end portion11aof the partition wall11and the vibration plate50form a first angular portion18, and the vibration plate50and a region11bwhich partitions the communicating passage14of the partition wall11form a second angular portion19. Here, the front end portion11aof the partition wall11is not limited so as to have the acute angle as described in the present embodiment, however it represents an end portion facing the reservoir100.

An adhesive agent17is continuously applied from the first angular portion18to the second angular portion19. The adhesive agent17applied to the first angular portion18gives fillet effect, so the adhesive agent17relieves stress on the first angular portion18. According to this, though the front end portion11ahas a narrower width in the partition wall11and is vulnerable to stress destruction, the adhesive agent17protects the front end portion11a. Therefore, even if the front end portion11aof the partition wall11is stressed by the bending of the nozzle plate20, the stress can be relieved to prevent destruction of the front end portion11a. Even though the partition wall11and the vibration plate50are pulled by bending of the nozzle plate20, the adhesive agent17relieves the stress and prevents occurrence of cracks in the vibration plate50.

Since the adhesive agent17is also applied to the second angle portion19, it prevents occurrence of cracks in a region11bpartitioning the communicating passage14of the partition wall11and the vibration plate50around the region11b. Additionally, in the present embodiment, a passage partitioned by the adjacent partition walls11comprises a communicating passage14, and the passage can include the ink supply path13. In this case, the second angular portion19is more firmly adhered by the adhesive agent17, so that it prevents occurrence of cracks more securely.

Furthermore, since the adhesive agent17is continuously applied from the first angular portion18to the second angular portion19, the first angular portion18and the second angular portion19are more firmly attached to the adhesive agent17, so that the front end portion11aand region11bof the partition wall11can be more securely protected. Even though cracks are formed in the vibration plate50in the areas of the first angular portion18and the second angular portion19, the first angular portion18and the second angular portion19are covered with the adhesive agent17. Therefore, penetration of the ink stored in the reservoir100into the cracks of the vibration plate50does not occur.

As mentioned above, since the areas of the front end portion11aand the region11bof the partition wall11and the vibration plate50at are protected from being cracked, an ink jet recording head with a high durability can be provided.

Furthermore, in the present embodiment, the adhesive agent17is made of epoxy resin or the like, and is applied to a surface of the nozzle plate20. When the nozzle plate20is adhered to the passage forming substrate10, the adhesive agent17flows along a boundary portion11c, which is a portion between the ink supply path13and the communicating passage14. Thus, the adhesive agent reaches the second angular portion19, the first angular portion18, and the vibration plate50disposed at opposite side of the nozzle plate20. The adhesive agent17flows due to a capillary phenomenon until it becomes hardened. That is, the adhesive agent17is continuously provided from the boundary portion11cto the first angular portion18. Thus, the adhesive agent17does not easily detach from the vibration plate50as compared with the case where the adhesive agent17is provided only at the first angular portion18or only from the first angular portion18to the second angular portion19. As a result, the angular portion18can be more securely protected by the adhesive agent17. When the nozzle plate20is adhered to the passage forming substrate10, the adhesive agent17arrives at the first angular portion18by the capillary phenomenon, therefore it is not necessary to separately perform an adhesive agent applying process from the boundary portion11cto the first angular portion18, so that it is possible to efficiently manufacture the liquid ejecting head, reducing the costs associated with manufacturing.

In addition, it is also possible to provide grooves in the front end portion11aor the region11bof the partition wall11in the width direction. Using the grooves, the adhesive agent17applied on the nozzle plate20causing the adhesive agent17to flows to the vibration plate50by the capillary phenomenon.

The piezoelectric element300, which is made up of a lower electrode membrane60, a piezoelectric layer70and an upper electrode membrane80, is provided on the vibration plate50, which forms a second base member. Here, the piezoelectric element300includes a portion having the lower electrode membrane60, the piezoelectric layer70and the upper electrode membrane80. In general, one electrode of the piezoelectric element300is used as a common electrode, while an electrode on the other side of the piezoelectric layer70acts an individual electrode for each pressure generating chamber12.

In the present embodiment, the lower electrode membrane60is used as a common electrode of the piezoelectric element300, and the upper electrode membrane80is used as an individual electrode of the piezoelectric element300, however the opposite configuration can be used in accordance with a specific driving circuit or a wiring condition. Here, the piezoelectric element300and the vibration plate50of the piezoelectric element300are referred to collectively as an actuator. Additionally, in the above described example, while the elastic membrane51and the insulating membrane52function as the vibration plate50, the vibration plate50is not limited to this configuration and other configurations may be used. For example, only the lower electrode membrane60may function as the vibration plate without the elastic membrane51and the insulating membrane52. The elastic membrane51, the insulating membrane52and the lower electrode membrane60may function as the vibration plate. Furthermore, the piezoelectric element300itself may substantially function as the vibration plate.

The piezoelectric layer70is made of a piezoelectric material, which has an electro-mechanical transduction function, and is more particularly made of a ferroelectric material having a perovskite structure. The piezoelectric layer is provided on the lower electrode membrane60. It is preferable that the piezoelectric layer70is formed from, for example, the ferroelectric material such as lead zirconate titanate (PZT), or the ferroelectric material including metal oxide such as niobium oxide (Nb2O5), nickel oxide (NiO), magnesium oxide (MgO). Specifically, lead titanate (PbTiO), lead zirconate titanate (Pb(Zr, Ti) O), lead zirconate (PbZrO), lanthanum lead titanate ((Pb, La), TiO), lanthanum lead titanate zirconate ((Pb, La) (Zr, Ti) O) and lead titanate zirconate niobate magnesium (Pb(Zr, Ti) (Mg, Nb) O) or the like may be used.

Lead electrodes90are connected to the corresponding upper electrode membrane80that acts as the individual electrode of the piezoelectric element300. The lead electrode90is made of, for example, gold (Au), and extends from the area near the end portion of the ink supply path13to the insulating membrane52.

A reservoir forming substrate30having a reservoir portion32which constitutes at least a portion of the reservoir100is adhered with intervention of adhesive agent35on the passage forming substrate10which has the piezoelectric element300formed thereon, that is, on the lower electrode membrane60, the insulating membrane52and the lead electrode90. In the present invention, the reservoir portion32passes through the reservoir forming substrate30in the thickness direction and extends in the width direction of the pressure generating chambers12, and as described above, communicates with the communicating portion15of the passage forming substrate10. The reservoir portion32and the communicating portion15together comprise the reservoir100, which acts as a common ink chamber of the pressure generating chambers12.

Additionally, a piezoelectric element holding portion31with a sufficient space so as not to hinder movement of the piezoelectric element300is formed in a region of the reservoir forming substrate30facing the piezoelectric element300. As long as the piezoelectric element holding portion31includes enough space so as not hinder the movement of the piezoelectric element300, it does not matter whether the space is sealed or not.

It is desirable to use a material having approximately the same coefficient of thermal expansion with that of the passage forming substrate10, such as glass or ceramic materials is used to form the reservoir forming substrate30. In the present embodiment, a silicon single crystal substrate of a material which is identical to that of the passage forming substrate10is used.

The reservoir forming substrate30also includes a through-hole33that extends through the reservoir forming substrate30in the thickness direction. An end portion of the lead electrode90extending from the respective piezoelectric elements300is exposed in the through-hole33.

A driving circuit200for driving the piezoelectric elements300is fixed on the reservoir forming substrate30. As the driving circuit200, for example, a circuit board or a semiconductor integrated circuit (IC) may be used. The driving circuit200is electrically connected to the lead electrode90by a connection wiring210formed of a conductive wire such as a bonding wire.

A compliance substrate40, which includes a sealing membrane41and a fixing plate42, is adhered on the reservoir forming substrate30a. Here, the sealing membrane41is formed of a material with a low rigidity and which has a flexibility (e.g., polyphenylene sulfide (PPS) film), and seals one surface of the reservoir portion32. The fixed plate42is formed of a hard material, such as metal (for example, stainless steel (SUS)). Since a region of the fixed plate42facing the reservoir100forms an opening43, one side surface of the reservoir100is sealed by the flexible sealing membrane41.

In the ink jet recording head of the present embodiment, ink is introduced through an ink inlet port connected to an external ink supply unit (not shown), and then, the inside portion from the reservoir100to the nozzle orifice21is filled with the ink. Then, according to a recording signal from the driving circuit200, a voltage is applied between the lower electrode membrane60and the upper electrode membrane80corresponding to each of the pressure generating chambers12. Accordingly, the elastic membrane51, the insulating membrane52, the lower electrode membrane60and the piezoelectric layer70are bent, so that the pressure in the respective pressure generating chambers12increases so as to eject ink droplets from the nozzle opening21.

Second Embodiment

In the first embodiment, the ink jet recording head has a piezoelectric element300which is capable of bending, but the invention is not limited to this embodiment, and, for example, it can be applied to a vertical vibration type ink jet recording head.FIG. 5is a cross-sectional view of an ink jet recording head related to a second embodiment, andFIG. 6is a cross-sectional view taken along a line VI-VI of theFIG. 5.

As shown inFIGS. 5 and 6, an ink jet recording head of the second embodiment includes a passage forming substrate112having a plurality of pressure generating chambers111, a nozzle plate114having a plurality of nozzle openings113which communicate with the respective pressure generating chambers111, a vibration plate115disposed on a surface of the passage forming substrate112opposite to the nozzle plate114, a piezoelectric element unit117having piezoelectric elements116disposed on the vibration plate115at a region corresponding to the respective pressure generating chambers111, and a head case119which is fixed to the vibration plate115and which includes a receiving portion118for receiving the piezoelectric element unit117.

A plurality of pressure generating chambers111which are partitioned by partition walls150are arranged in parallel to the width direction on one surface of the passage forming substrate112which forms a first base member. For example, in the present embodiment, the pressure generating chambers111are arranged in parallel in the passage forming substrate112. A reservoir121for supplying ink to the respective pressure generating chambers111is formed in the thickness direction of the passage forming substrate112in an area adjacent to the pressure generating chambers111. The reservoir121communicates with the respective pressure generating chambers111via an ink supply path122. In the present embodiment, the ink supply path122is formed to have a narrower width than that of the pressure generating chambers111, and thus the flow resistance of the ink flowing from the reservoir121into the pressure generating chambers111can be kept constant.

Island-shaped wall portions151extending to the ink flow are provided in the corresponding ink supply path122of the passage forming substrate112. By the island-shaped wall portions151, area of ink passage in the ink supply path122becomes narrower, so it can prevent pressure reduction in the pressure generating chambers111.

Moreover, a nozzle communicating hole123extending through the passage forming substrate112is adjacent to the pressure generating chamber111opposite to the reservoir121. The reservoir121communicates with an ink introduction path141formed to penetrate the head case119in the width direction. The ink introduction path141is a passage that introduces ink from an ink cartridge (not shown) to the reservoir121. In other words, a liquid passage constituted by the reservoir121, the ink supply path122, the pressure generating chamber111and the nozzle communicating hole123is formed on the passage forming substrate112.

In the present embodiment, the passage forming substrate112is made of a silicon single crystal substrate, and the pressure generating chambers111provided on the passage forming substrate112are formed by etching the passage forming substrate112.

On one surface of the passage forming substrate112, the nozzle plate114having the nozzle openings113formed therein is adhered by adhesive agent, and the respective nozzle openings113communicate with the respective pressure generating chamber by way of the nozzle communicating hole123formed in the passage forming substrate114.

In addition, the vibration plate115is adhered to the opposite surface of the passage forming substrate112, that is, the orifice surface of the pressure generating chamber111, so each pressure generating chamber111is sealed by the vibration plate115.

The vibration plate115comprises a composite plate125which is made up of an elastic membrane124and a support plate125. The elastic membrane124is formed of, for example, an elastic member like resin film. The support plate125is formed of, for example, a metallic material. The elastic membrane124side is adhered to the passage forming substrate112. In one example of the present embodiment, the elastic membrane124is formed of a polyphenylene sulfide (PPS) film, and the support plate125is formed of stainless steel (SUS). An island-shaped portion126in contact with a front end portion of the piezoelectric element116is provided within an area of the vibration plate115facing the respective pressure generating chamber111. A thin-walled member127having a width smaller than those of other members is formed in an area of the vibration plate115facing the circumferential region of the respective pressure generating chamber111, and the island-shaped portions126are provided on the thin-walled member127. In the present embodiment, a compliance portion128of the thin-walled member, which is formed by etching the support plate125and is substantially made up only of a elastic membrane, is provided in the region of the vibration plate115facing the reservoir121. In addition, when the pressure in the reservoir121is changed, the compliance portion128absorbs the changed pressure by transformation of the elastic membrane124, so it keeps the pressure in the reservoir121to be constant.

The vibration plate115and a front end portion150aof the partition wall150disposed at the side of the reservoir121form a first angular portion18A, and the vibration plate115and a region150bin the partition wall150partitioning the ink supply path122form a second angular portion19A.

The adhesive agent17A is continuously provided from the first angular portion18A to the second angular portion19A. The adhesive agent17A provided on the first angular portion18A gives the same effect that a fillet of the adhesive agent17A is formed on the first angular portion18A, so that it relieves stress on the first angular portion18A. Using this configuration, although the front end portion150aof the partition wall150has a narrow width and is vulnerable to stress destruction, the front end portion150ais protected by the adhesive agent17A. Therefore, even if the front end portion150aof the partition wall150is stressed by bending of the nozzle plate114, the stress is relieved to prevent destruction of the front end portion150a. Even though the partition wall150and the vibration plate115are pulled by the bending of the nozzle plate114, the adhesive agent17A relieves the stress and prevents occurrence of cracks in the vibration plate115.

The adhesive agent17A is also provided to the second angle portion19A, so that it prevents occurrence of cracks in a region150bpartitioning the ink supply path122of the partition wall150or in the vibration plate115of at a vicinity of the region150b.

Furthermore, the adhesive agent17A is continuously provided from the first angular portion18ato the second angular portion19A, and thus the first angular portion18aand the second angular portion19A are more strongly adhered by the adhesive agent17A, so the region150band the front end portion150aof the partition wall150can be more securely protected. Thus, even though cracks occur in the vibration plate115near the area of the first angular portion18A and the second angular portion19A, the first angular portion18A and the second angular portion19aare covered with the adhesive agent17A, so ink is prevented from entering into cracks of the vibration plate115.

In the present embodiment, the adhesive agent17A is provided to an angular portion152formed by the island-shaped wall portion151and the vibration plate115. According to this, it is possible to prevent cracks in a front end portion151aof the island-shaped wall portion151or in a region151bof the island-shaped wall portion151facing the partition wall150, and also possible to prevent cracks in the vibration plate115near the front end portion151aand the region151b.

As mentioned above, crack occurrence is prevented in the region150b, the front end portion150aof the partition wall150, and the vibration plate115near the region150band the front end portion150a, thus an ink jet recording head with a high durability can be provided.

Furthermore, in the present embodiment, the adhesive agent17A is made of, for example, epoxy resin or the like, and is applied to one surface of the nozzle plate114. Here, when the nozzle plate114is adhered to the passage forming substrate112, by a capillary phenomenon, the adhesive agent17A flows from a front end portion150cof the partition wall150to the vibration plate115disposed at opposite side. The adhesive agent17A reaches the first angular portion18A and the second angular portion19A, and then is hardened. That is, the adhesive agent17A is continuously provided from the end portion150cto the second angular portion19. Thus, the adhesive agent17A is more consistently applied from the vibration plate115as compared with the case where the adhesive agent17A is provided only at the first angular portion18A or only from the first angular portion18A to the second angular portion19A. As a result, the first angular portion18A and the second angular portion19A can be more securely protected by the adhesive agent17A. When the nozzle plate114is adhered to the passage forming substrate112, the adhesive agent17A arrives at the first angular portion18A by the capillary phenomenon, therefore it is not necessary to perform a separate adhesive agent applying process from the end portion150cto the first angular portion18A, so the liquid ejecting head can be more efficiently manufactured, providing a lower cost liquid ejecting head.

In addition, it is also possible to provide grooves in the front end portion150aof the partition wall150in the width direction. Using the grooves, the adhesive agent17A applied on the nozzle plate114easily flows to the vibration plate115by the capillary phenomenon.

A front end of an active region of the piezoelectric element116constituting the piezoelectric element unit117is fixed, so as to be in contact with the island-shaped portion126of the vibration plate115.

In this embodiment, the piezoelectric element116that is a pressure generating device for generating pressure for discharging ink droplet is integrally formed as the piezoelectric element unit117. That is, a piezoelectric element forming member132is formed by vertically and alternately forming layers of a piezoelectric material129and electrode forming materials130,131. Each piezoelectric element116is formed by separating the piezoelectric element forming member132in the form of comb teeth corresponding to the respective pressure generating chambers111. In other words, in the present embodiment, a plurality of the piezoelectric elements116are integrally formed. Meanwhile, an inactive region, which is not involved in vibration of the piezoelectric element116, a base end of the piezoelectric element116is fixed to a fixing substrate133. A circuit substrate135having wirings134which provide signals for driving the respective piezoelectric elements116is connected to the vicinity of the base end of the piezoelectric element116opposite to the fixing substrate133. In the present embodiment, the piezoelectric element unit117comprises the piezoelectric element116(or the piezoelectric element forming member132), the fixed substrate133, and the circuit substrate135.

The front end of the piezoelectric element116of the piezoelectric element unit117is fixed so as to be in contact with the island-shaped portion126of the vibration plate115. For example, in the present embodiment, as described above, the head case119is fixed to the vibration plate115, and the piezoelectric element unit117is received inside the receiving portion118of the head case119. The fixing substrate133having the piezoelectric element116fixed thereto is fixed to the head case119opposite to the piezoelectric element116.

In the head case119, a plurality of the receiving portions118receiving the piezoelectric element unit117(FIG. 5shows one receiving portion) are installed, and one piezoelectric element unit117is disposed in one receiving portion118.

A wiring substrate137is fixed in the head case119. The wiring substrate137includes a plurality of conductive pads136to which the wirings134of the circuit substrate135are connected respectively. As a result, the receiving portion118of the head case119is substantially closed by the wiring substrate137. The wiring substrate137includes a slit-shaped opening138formed in a region facing the receiving portion118of the head case119. Therefore, the circuit substrate135is provided to appear outside the receiving portion118from the opening portion138of the wiring substrate137.

In the present embodiment, the circuit substrate135comprising the piezoelectric element unit117includes a flexible printed circuit (FPS) substrate to which a driving IC (not shown) for driving the piezoelectric element116is provided, such as a tape carrier package (TCP), a chip on film (COF) and a flexible flat cable (FFC) or the like. The base end portion of the respective wiring134of the circuit substrate135is connected to the electrode forming materials130,131which comprise the piezoelectric element116by means of, for example, a solder, an anisotropic conductive material or the like. The front end of the respective wiring134of the circuit substrate135is connected to the conductive pads136of the wiring substrate137. Specifically, the front end portion of the circuit substrate135extending from the opening portion138of the wiring substrate137to the outside of the receiving portion118bends along the surface of the wiring substrate137. The wirings134are connected to the conductive pads136of the wiring substrate137respectively by soldering (not shown).

The ink jet recording head changes the volume of the corresponding pressure generating chamber111by driving the piezoelectric element116and the vibration plate115, causing an ink droplet to be discharged from a predetermined nozzle opening113. Specifically, when ink is supplied to the reservoir121from an ink cartridge (not shown), ink is distributed to corresponding pressure generating chamber111by way of the ink supply path122. By applying a voltage to the piezoelectric element116, the piezoelectric element116is contracted. The vibration plate115is moved with the piezoelectric element116, causing the volume of the pressure generating chamber111can be increased, as a result, ink is drawn to the pressure generating chamber111. After ink is filled inside the pressure generating chamber111to the nozzle opening113, voltage applying to the electrode forming materials130,131of the piezoelectric element116is stopped according to a recording signal supplied through the wiring substrate137. So, the piezoelectric element116is extended to return to the original state, and the vibration plate115is also moved to return to the original state. Consequently, the volume of the pressure generating chamber111is contracted, and then the pressure inside the pressure generating chamber111is increased such that ink is discharged from the nozzle orifice113.

Other Embodiments

Although the invention has been described above with reference to two embodiments, the invention is not limited to the above described embodiments, and other embodiments may be used without departing from the meaning and scope of the invention.

In the first and the second embodiments, while the adhesive agents17,17A are continuously provided to the nozzle plates20,114and the passage forming substrates10,112, in an alternative configuration the adhesive agents17,17A can be separately provided. That is, after the adhesive agents17,17A are applied to the first angular portions18,18A and the second angular portions19,19A respectively, the nozzle plates20,114can be adhered to the passage forming substrates10,112. In this case, since the adhesive agents17,17A are provided to the first angular portions18,18A and the second angular portions19,19A, stress on the front end portion11a,150aand the region11b,150bof the partition wall11,150is relieved, so it is possible to prevent cracks.

The ink jet recording head of the above-mentioned embodiment constitutes a part of a recording head unit including an ink passage that communicates with an ink cartridge and the like, and is disposed in an ink jet type recording apparatus.FIG. 7is a schematic view showing an example of the ink jet type recording apparatus. As shown, ink cartridges2A and2B serve as an ink supply unit and are detachably installed to recording head units1A and1B having ink jet recording heads. A carriage3in which the recording head units1A and1B is installed is provided such that the carriage3can move freely to axial direction of a carriage axis5disposed in a main body4of the apparatus. The recording head units1A and1B, for example, discharge a black ink composition and a color ink composition, respectively. A driving force of a driving motor6is transmitted to the carriage3by intervention of a plurality of gears (not shown) and a timing belt7, so that the carriage3having the recording head units1A and1B mounted thereon moves along the carriage axis5. In the meanwhile, since a platen8is disposed along the carriage axis5in the main body4of the apparatus, a recording sheet S, which is a recording medium fed by a sheet feeding roller (not shown), is transported on the platen8.

In addition to the above described embodiments which describe an ink jet recording head, the basic configuration of the liquid ejecting head can also be applied not only to general liquid ejecting heads, but also to apparatuses ejecting liquid other than ink. The liquid ejecting head includes, for example, various recording heads used in image recording apparatuses such as a printers or the like, color material ejecting heads used for manufacturing a color filter such as a liquid crystal display or the like, an electrode material ejecting heads used for forming electrode of an organic EL display, an electric field display or the like, and a bio organic substance ejection heads used for manufacturing a bio-chip.