Liquid ejection apparatus and connection method for flexible wiring board

A liquid ejection apparatus includes a channel unit with a plurality of nozzles and pressure chambers configured to communicate with respective nozzles, and a plate provided on the channel unit to cover pressure chambers in a first direction from the pressure chambers, the plate comprising a plate surface extending along a second direction perpendicular to the first direction. The liquid ejection apparatus includes a plurality of drive elements arranged over the pressure chambers. The liquid ejection apparatus includes a plurality of contact terminals electrically connected to their respective drive elements at a terminal placement surface which is non-parallel with the plate surface and includes a portion of the terminal placement surface that is offset from the plate surface. The liquid ejection apparatus includes a flexible wiring board configured to be electrically connected to the contact terminals.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Japanese Patent Application No. 2013-034287 filed on Feb. 25, 2013, which is incorporated herein by reference in its entirety.

FIELD OF DISCLOSURE

The disclosure herein relates to a liquid ejection apparatus and a connection method for a flexible wiring board.

BACKGROUND

A known liquid ejection apparatus (e.g., a liquid droplet ejection head) includes a nozzle plate having nozzles formed thereon, a channeled substrate including channels, e.g., pressure chambers configured to fluidly communicate with the corresponding nozzles, and piezoelectric elements to eject ink from the corresponding nozzles.

In the known liquid ejection apparatus, a vibration plate is provided on the channeled substrate to cover the pressure chambers. The piezoelectric elements are provided on the vibration plate to oppose the corresponding pressure chambers. A seal portion configured to cover the piezoelectric elements is provided on the vibration plate. The piezoelectric elements are sealed from an external space by the seal portion.

Each piezoelectric element includes an individual electrode (e.g., an upper electrode film). A connection terminal is connected to each individual electrode of the piezoelectric elements. The connection terminal extends from the piezoelectric element to an exterior of the seal portion in a surface of the vibration plate. A flexible wiring board or flexible printed circuit board on which a drive circuit is mounted, is connected to the connection terminals provided on a surface of the vibration plate in correspondence with respective piezoelectric elements. The drive circuit is configured to apply voltage to the respective piezoelectric elements, via wirings of the flexible wiring board, based on an instruction from an external controller.

To ensure electrical connection between the connection terminals and the flexible wiring board when the connection terminals are connected to the flexible wiring board by pressing the flexible wiring board against the connection terminals, each connection terminal needs to have a certain area. In a structure in which the connection terminal extending from each piezoelectric element is provided on a surface of the vibration plate, a greater surface area may be required for the vibration plate to ensure that sufficient area is provided for the connection terminals. However, this additional surface area will lead to increase in the size of the liquid ejection apparatus. Especially, in the field of printers, there is a trend to increase the number of nozzles recently. In association with the trend, the numbers of the piezoelectric elements and the connection terminals are increased, which will lead to further increase in the size of the liquid ejection apparatus.

SUMMARY

Aspects of the disclosure relate to a liquid ejection apparatus that may realize reduction in the size of the liquid ejection apparatus while maintaining an area for each connection terminal.

According to an aspect of the present teaching, there is provided a liquid ejection apparatus. The liquid ejection apparatus includes a channel unit including a liquid channel comprising a plurality of nozzles, and a plurality of pressure chambers configured to communicate with respective nozzles. The liquid ejection apparatus also includes a plate provided on the channel unit to cover the plurality of the pressure chambers in a first direction from the pressure chambers, the plate comprising a plate surface extending along a second direction perpendicular to the first direction. The liquid ejection apparatus also includes a plurality of drive elements arranged over the plate in correspondence with the plurality of the pressure chambers, and a plurality of contact terminals electrically connected in correspondence with respective drive elements, the plurality of the contact terminals are provided at a terminal placement surface, wherein the terminal placement surface is non-parallel with the plate surface and includes at least a portion of the terminal placement surface that is offset from the plate surface. The liquid ejection apparatus further includes a flexible wiring board configured to be electrically connected to the plurality of the contact terminals.

In a further aspect, a method for connecting a flexible wiring board to a liquid ejection apparatus is disclosed. The method includes connecting a flexible wiring board to each of a plurality of the contact terminals disposed on a terminal placement surface such that the flexible wiring board is pressed against the terminal placement surface in a direction normal to the terminal placement surface. The terminal placement surface is non-parallel with a plate surface of a plate provided on a channel unit and includes at least a portion of the terminal placement surface that is offset from the plate surface, wherein the channel unit including a plurality of nozzles and a plurality of pressure chambers and wherein each of the plurality of contact terminals are electrically connected to corresponding drive elements arranged over the plate in correspondence with the plurality of pressure chambers.

In a still further aspect, a printer includes a liquid ejection apparatus. The liquid ejection apparatus includes a channel unit comprising a liquid channel including a plurality of nozzles and a plurality of pressure chambers configured to communicate with respective nozzles, and a plate provided on the channel unit to cover the plurality of the pressure chambers in a first direction from the pressure chambers, the plate comprising a plate surface extending along a second direction perpendicular to the first direction. The liquid ejection apparatus further includes a plurality of drive elements arranged over the plate in correspondence with the plurality of the pressure chambers. The liquid ejection apparatus also includes a plurality of contact terminals electrically connected in correspondence with respective drive elements, the plurality of the contact terminals are provided at a terminal placement surface, wherein the terminal placement surface is non-parallel with the plate surface and includes at least a portion of the terminal placement surface that is offset from the plate surface. The liquid ejection apparatus includes a flexible wiring board configured to be electrically connected to the plurality of the contact terminals.

DETAILED DESCRIPTION

In general, the present disclosure relates generally to a liquid ejection apparatus and a connection method for a flexible wiring board, such as can be used in an inkjet printer. In particular, in a liquid ejection apparatus, and methods, according to example aspects of the disclosure, a terminal placement surface is non-parallel with the plate surface and includes at least a portion of the terminal placement surface that is offset from the plate surface. This terminal placement surface may be an inclined surface or a curved surface. When projected areas of an inclined surface, a curved surface, and a flat surface parallel to the plate are all same when viewed from a direction perpendicular to the plate, surface areas of the inclined surface and/or the curved surface may greater than the surface area of the flat surface. Therefore, the size of the terminal placement surface in a third direction may be reduced while a certain area may be ensured for each contact terminal. Accordingly, the size of the liquid ejection apparatus may be reduced. In other words, by disposing the terminal placement surface non-parallel with and offset from the plate surface, adequate surface area for electrical and physical connection of the flexible wiring board can be accomplished while maintaining a compact size of the overall liquid ejection apparatus.

In an example embodiment, the aspects of the disclosure may be applied to an inkjet printer1. The top of the inkjet printer1may be positioned on a front side of the sheet ofFIG. 1, e.g., a side of the sheet ofFIG. 1facing toward you. The bottom of the inkjet printer1may be positioned on a rear side of the sheet ofFIG. 1. The disclosure may be described in connection with the top and bottom direction, as defined above.

In the example shown inFIG. 1, the inkjet printer1includes a platen2, a carriage3, and a liquid ejection apparatus, e.g., an inkjet head4. The inkjet printer1also includes, in this embodiment, a transporting mechanism5.

In this example embodiment, the platen2is configured to support a recording medium, e.g., a recording sheet100, on an upper surface thereof. The carriage3is configured to reciprocate in a scanning direction along two guide rails10,11in an area to oppose the platen2. An endless belt14may be connected to the carriage3. A carriage drive motor15may drive the endless belt14to move the carriage3along the scanning direction.

As shown in the example ofFIG. 1, the inkjet head4is mounted on the carriage3. The inkjet head4may be configured to move together with the carriage3along the scanning direction. The inkjet head4may be connected to ink cartridges17installed in the printer1, via a tube (not depicted). The inkjet head4includes nozzles30formed on a lower surface thereof (e.g., the rear side of the sheet ofFIG. 1). The inkjet head4is configured to eject ink, which is supplied from the ink cartridge17, from the nozzles30onto the recording sheet100placed on the platen2.

In at least some embodiments, the transporting mechanism5may comprise feeding rollers18,19that may be disposed to interpose the platen2therebetween in a sheet feeding direction. The transporting mechanism5may be configured to feed the recording sheet100placed on the platen2by the feeding rollers18,19in the sheet feeding direction.

In example embodiments, the inkjet printer1is configured to eject ink from the inkjet head4mounted on the carriage3onto the recording sheet100placed on the platen2while moving the carriage3along the scanning direction. The feeding rollers18,19may feed the recording sheet10in the sheet feeding direction by a predetermined amount. An ink ejection operation by the inkjet head4and a feeding operation of the recording sheet100by the transporting mechanism5may be alternately and repeatedly performed, to print, for example, an image on the recording sheet100.

As depicted in the example embodiment shown inFIGS. 2-4, the inkjet head4includes a nozzle plate20, a channeled member21, a piezoelectric actuator22, a cover member23, and a wiring member, e.g., a chip on film (“COF”)24. InFIG. 3, an outline of a possible position of the cover member23depicted inFIG. 2is shown via a chain double-dashed line, and the COF24is omitted. Letter “I” inFIG. 4Arepresents a possible location of ink in an ink channel formed in the channeled member21and the nozzle plate20.

As depicted in the example ofFIG. 4A, the nozzle plate20may be a plate member constructed from any of a number of materials, such as, for example, a synthetic resin, e.g., polyimide, or metallic material. In this example, the nozzle plate20includes the nozzles30passing therethrough in its thickness direction (e.g., a first direction). As depicted inFIG. 3, the nozzles30may be arranged in two arrays along a sheet feeding direction, such as is shown inFIGS. 1-3, and is approximately normal to the vertical direction and the scanning direction as seen inFIG. 4A. The nozzles30may be arranged in a staggered or zigzag manner such that one array of the nozzles30may be shifted by a half of the nozzle pitch from the other array of the nozzles30. The nozzle plate20may be bonded to a surface of the channeled member21, for example to the lower surface.

In example embodiments, the channeled member21may be constructed from a metallic material or silicon. The upper surface of the channeled member21may include an ink supply opening31that is connected to the ink cartridge17(refer to, for example,FIG. 1). In such embodiments, the channeled member21includes two manifolds32formed in an interior thereof, so as to extend along the sheet feeding direction. The two manifolds32may be connected to the one ink supply opening31such that ink supplied from the ink cartridge17is supplied to each of two manifolds32.

In the embodiment shown, the channeled member21includes pressure chambers33formed on the upper surface thereof (e.g., a side opposite to a side to which the nozzle plate20is bonded). The pressure chambers33are configured to fluidly communicate with the corresponding nozzles30. As seen in the example ofFIG. 4A, the pressure chambers33may be disposed in two arrays, in correspondence with the nozzles30, along the sheet feeding direction, for example in a zigzag or staggered manner. The pressure chambers33are covered with a vibration plate40of the piezoelectric actuator22from above. Each pressure chamber33may have a generally elliptical plane shape that is elongated along the scanning direction. Alternative chamber shapes, such as rectangular pressure chamber shapes, may be used as well. In the embodiment shown, an end of the pressure chamber33in its longitudinal direction, e.g., the scanning direction, fluidly communicates with the corresponding nozzle30. As depicted in the example embodiment shown inFIGS. 3 and 4, the nozzles30in the left nozzle array inFIGS. 3 and 4fluidly communicate with the left ends of the corresponding pressure chambers33. The nozzles30in the right nozzle array inFIGS. 3 and 4fluidly communicate with the right ends of the corresponding pressure chambers33. In the embodiment shown, each nozzle30overlaps with an outward end of the corresponding pressure chamber33in the plan view. In other words, the nozzles30in the left and right nozzle arrays inFIGS. 3 and 4overlap with the left and right ends of the corresponding pressure chambers33, respectively. However, in alternative embodiments, the nozzles30may not overlap with the pressure chambers33, but rather are offset from the pressure chambers33in a third direction (e.g., along the scanning direction as show n inFIG. 4A).

As depicted inFIGS. 3 and 4, a recess portion35may be disposed on the upper surface of the channeled member21at an area between the arrays of the pressure chambers33. In the example shown, the recess portion35extends along a direction in which the nozzles30and the pressure chambers33are arranged (e.g., along the sheet feeding direction). A portion of each side inner wall surface of the recess portion35in its width direction includes a terminal placement surface49that is non-parallel with a plate surface of a plate provided on a channel unit and includes at least a portion of the terminal placement surface that is offset from the plate surface. In the example shown inFIGS. 3 and 4, the terminal placement surface49is illustrated as an inclined surface that is inclined with respect to the surface40aof the vibration plate40(e.g., the scanning direction perpendicular to a direction in which the recess portion35extends). The terminals46,48of the piezoelectric actuator22may be disposed on the inclined surface, e.g., a terminal placement surface49. The recess portion35may be divided into two cavities36by a wall portion53of the cover member23.

As depicted inFIGS. 2-4, each of two arrays of the pressure chambers33may be disposed to overlap the respective manifolds32. The pressure chambers33may fluidly communicate with the manifolds32that may be disposed thereunder. As depicted inFIG. 4A, the channeled member21may comprise individual ink channels34branched from the manifolds32and configured to fluidly communicate with the corresponding nozzles30via the pressure chambers33. In the example embodiment, the nozzle plate20and the channeled member21may correspond to a channel unit.

In the embodiment shown, the piezoelectric actuator22is disposed on the upper surface of the channeled member21. As depicted inFIGS. 2-4, the piezoelectric actuator22includes the vibration plate40, a piezoelectric layer41, individual electrodes42, and a common electrode43.

Each of the two vibration plates40(e.g., one per array of pressure chambers) may be disposed on the upper surface of the channeled member21to cover the respective array of the pressure chambers33. The vibration plate40may include, for example, metallic material or ceramic material. In another embodiment, when the channeled member21is formed of silicon, a silicon dioxide film may be formed on the surface of the channeled member21. The silicon dioxide film may serve as the vibration plate40. The vibration plate40may comprise a surface40athat extends in the scanning direction. The surface40amay have a common electrode43and the wirings45,47formed thereon. Accordingly, when the vibration plate40is formed of conductive material, e.g., metal, an insulator film may be formed on the surface40aof the vibration plate40.

The piezoelectric layer41is disposed on the surface40aof each vibration plate40. In some embodiments, the piezoelectric layer41has a rectangular plane shape. The piezoelectric layer41includes a piezoelectric material whose main components may be, for example, ferroelectric lead zirconate titanate (PZT), which may include a solid solution of lead titanate and lead zirconate. The piezoelectric layer41may be directly formed on the surface40aof the vibration plate40using a known film or layer formation technique, such as the spattering method or sol-gel method. In another embodiment, the piezoelectric layer41may be bonded to the vibration plate40, after an unbaked thin sheet of the piezoelectric material is baked. As depicted in the example shown inFIGS. 2 and 3, the piezoelectric layer41is disposed to cover each array of the pressure chambers33such that the longitudinal direction of the piezoelectric layer41is parallel to the nozzle arrangement direction.

In the embodiment shown, the individual electrodes42are disposed at areas of the upper surface of the piezoelectric layer41opposing the respective pressure chambers33. Accordingly, the individual electrodes42may be arranged in two arrays, along the nozzle arrangement direction, similar to the pressure chambers33. Each individual electrode42may have an elliptical plane shape slightly smaller than the shape of the pressure chamber33. The individual electrodes42may be positioned to oppose the central portions of the corresponding pressure chambers33.

In the embodiment shown, wirings45for the individual electrodes42are disposed on the surface40aof the vibration plate40. The wiring45may be connected to an end of the respective individual electrode42opposite to the nozzle30in plan view The wiring45may extend from the respective individual electrode42in a longitudinal direction of the pressure chamber33(e.g., the right-left direction inFIG. 3) along the surface40aof the vibration plate40. More specifically, as depicted inFIG. 3, the wirings45may extend rightward and leftward from the respective individual electrodes42of the left and right arrays inFIG. 3, respectively. The recess portion35(e.g., the two cavities36) may be disposed between the two piezoelectric layers41of the channeled member21in line with the piezoelectric layers41in the scanning direction. As shown, the wirings45inwardly extend from the respective individual electrodes42of each array to the recess portion35(e.g., the two cavities36) disposed on the inner side of the respective array of the individual electrodes42.

A terminal46for the individual electrode42may be disposed at an end of each wiring45(e.g., an end opposite to the individual electrodes42). In the example shown, the terminals46are arranged in two arrays along the scanning direction in correspondence with the respective arrays of the individual electrodes42between the arrays of the individual electrodes42. More specifically, the array of the terminals46corresponding to the left array of the individual electrodes42inFIG. 3may be disposed along the nozzle arrangement direction at an inclined surface formed at the inner wall surface of the left cavity36. The array of the terminals46corresponding to the right array of the individual electrodes42inFIG. 3may be disposed along the nozzle arrangement direction at an inclined surface formed at the inner wall surface of the right cavity36. The inclined surfaces of the cavities36where the terminals46for the individual electrodes42may be disposed may be hereinafter referred to as “the terminal placement surface49”. The COF24may be connected to the respective array of the terminals46disposed on the respective terminal placement surface49. Thus, the individual electrodes42may be connected to the driver ICs50mounted on the COFs24.

As depicted inFIG. 4A, the common electrode43is disposed between the piezoelectric layer41and the vibration plate40. The common electrode43may extend across the pressure chambers33along the nozzle arrangement direction, as depicted inFIG. 3. In the embodiment shown, the common electrode43contacts almost the entire lower surface of the corresponding piezoelectric layer41. As depicted inFIG. 3, wirings47for the common electrode43are disposed on the surface40aof the vibration plate40along the scanning direction. In such an arrangement, the two wirings47may be connected to one common electrode43. The two wirings47connected to the left common electrode43inFIG. 3may extend to the left cavity36. A terminal48for the common electrode43may be disposed at an end of each wiring47. The terminals48may be disposed on the terminal placement surface49of the inner wall surface of the left cavity36. Similarly, the two wirings47connected to the right common electrode43inFIG. 3may extend to the right cavity36. The terminals48disposed at ends of the wirings47may be disposed on the inclined terminal placement surface49of the right cavity36. The COFs24may be connected to the terminals48. Thus, the common electrodes43may be connected to the driver ICs50mounted on the COFs24and constantly maintained in ground potential by the driver ICs50.

Each of the terminals46for the individual electrodes42and the terminals48for the common electrodes43may have a circular shape in plan view. The terminal placement surface49may be inclined with respect to the vibration plate40. Therefore, inFIG. 3which is viewed from a direction perpendicular to the vibration plate40, the terminals46,48may be depicted in an elliptical shape in which distances, e.g., widths, of the terminals46,48in the scanning direction may be smaller. The terminals46and the terminals48may correspond to example embodiments of contact terminals.

As depicted inFIG. 4A, a piezoelectric element44may be disposed at a portion of the piezoelectric layer41opposing one of the pressure chambers33between one of the individual electrodes42and the common electrode43. In this example embodiment, the piezoelectric element44corresponds to an example implementation of a drive element. For example, the piezoelectric element44may deform when a drive signal is supplied to the individual electrode42from the driver IC50, and may apply ejection energy to ink in the pressure chamber33. Each piezoelectric element44may be polarized in its thickness direction. The piezoelectric elements44may be arrayed along the nozzle arrangement direction in correspondence with each of the two arrays of the pressure chamber33. The two arrays of the piezoelectric elements44may be arranged in the scanning direction. InFIG. 3, one piezoelectric layer41may be disposed across the pressure chambers33that may be arranged in array. One piezoelectric layer41may be provided for a plurality of the individual electrode42. In another embodiment, one piezoelectric layer41may be provided in correspondence with a single individual electrode42. In the example embodiment, the individual electrodes42may be disposed on the upper surface of the piezoelectric layer41and the common electrodes43may be disposed on the lower surface of the piezoelectric layer41. In another embodiment, the individual electrodes42may be disposed on the lower surface of the piezoelectric layer41and the common electrodes43may be disposed on the upper surface of the piezoelectric layer41.

In the example embodiment shown, the cover member23is bonded to the channeled member21and the vibration plates40while covering the two piezoelectric layers41. The cover member23may be provided to reduce the entry of external moisture into the piezoelectric elements44by blocking the piezoelectric layers41from the atmosphere. As depicted inFIGS. 2-4, the cover member23may comprise two seal portions51, a connecting portion52and the wall portion53.

In example configurations, each seal portion51may have a rectangular box shape. The seal portion51may be disposed at the surface40aof the vibration plate40such that the seal portion51is upside down with the bottom of the seal portion51being placed in an upper side. The seal portion51may entirely cover the corresponding piezoelectric layer41of a rectangular shape from above. The connecting portion52may be disposed between the two seal portions51and connect the two seal portions51. The connecting portion52may have two through holes52aof a rectangular shape elongated in the nozzle arrangement direction. A portion of the connecting portion52between the two through holes52amay be provided with the wall portion53extending downward along the longitudinal direction of the through holes52a. The entire length of the wall portion53may contact with the bottom surface of the recess portion35of the channeled member21to separate or divide the two arrays of the piezoelectric elements44. The wall portion53may divide the recess portion35into the two cavities36. Upper two corners of the wall portion53may be chamfered to form inclined surfaces53a.

In example embodiments, each of the two COFs24inserted into the corresponding through hole52aof the cover member23may be bonded to the terminal placement surface49of the corresponding cavity36. The driver IC50may be mounted on a portion of each COF24extending outside the cover member23. The driver IC50may be placed on the upper surface of each seal portion51of the cover member23. Wirings (not depicted) formed on each COF24may electrically connect the driver IC50with the terminals46for the individual electrodes42and the terminals48for the common electrode43that are provided on the terminal placement surface49.

Various circuits configured to drive the piezoelectric elements44may be integrated in the driver IC50. The COFs24may be connected to a control board (not depicted). Various control signals may be transmitted from the control board to the driver IC50mounted on each of the two COFs24. The driver IC50may be configured to output drive signals generated based on the control signals input from the control board, to the individual electrodes42, so that the piezoelectric elements44may be individually driven. The driver IC50may keep the potential of the common electrode43at the ground potential.

In the example embodiment, the flexible wiring board, e.g., the COF24on which the driver IC50may be mounted, is connected to the terminals46,48provided on the terminal placement surface49. In another embodiment, the flexible wiring board on which the driver IC50might not be mounted, is connected to the terminals46,48.

In use, a drive signal may be input from the driver IC50to an individual electrode42. This drive signal may cause the vibration plate40covering the corresponding pressure chamber33to deforms to project toward the pressure chamber33, to change the volumetric capacity of the pressure chamber33. Accordingly, pressure (e.g., ejection energy) is applied to ink in the pressure chamber33to eject an ink droplet from the corresponding nozzle30fluidly communicating with the pressure chamber33.

In example embodiments, each COF24is bonded to the terminals46,48on the terminal placement surface49, for example using a conductive bonding material having fluidity, e.g., solder or conductive adhesive. For example, the COF24may be bonded to the terminals46,48using anisotropic conductive adhesive. The anisotropic conductive adhesive, e.g., an anisotropic conductive film (ACF) or anisotropic conductive paste (ACP), may comprise thermosetting resin in which conductive particles may be dispersed. The anisotropic conductive adhesive may be applied to the terminal placement surface49such that the terminals46,48may be covered. Then, the COF24may be pressed against the terminal placement surface49while the COF24is heated. Great pressure may be locally applied to a portion of anisotropic conductive adhesive that may exist between the terminals46,48disposed on the terminal placement surface49and terminals of the COF24, so that the terminals of the COF24and the terminals46,48may be electrically connected by the conductive particles. At the same time, the anisotropic conductive adhesive that may be pushed outward when the pressure is applied thereto may be hardened by the application of heat and the COF24and the terminal placement surface49may be mechanically bonded.

As depicted in the example configuration shown inFIG. 4A, an inner wall surface of the cavity36, e.g., the terminal placement surface49, where the terminals46for the individual electrodes42and the terminals48for the common electrode43are disposed, is inclined with respect to the surface40aof the vibration plate40. Referring toFIG. 4B, the terminal placement surface49ainclined with respect to the surface40aand a terminal placement surface49bparallel to the surface40amay be compared. As depicted inFIG. 4B, the terminal placement surface49ais inclined 01 degrees with respect to the surface40a. The terminal placement surface49amay have a length L1 and a width W. The length L1 may be equal to W/cos θ1. The length L1 may be greater than the width W (L1>W) because cos θ1<0 (θ1≠0 degrees). A length L2 of the terminal placement surface49bmay be equal to the width W. Therefore, the length L1 may be greater than the length L2. When projected areas of the terminal placement surfaces49aand49bare the same when viewed from a direction perpendicular to the surface40a, a greater surface area may be provided for the terminal placement surface49athan the terminal placement surface49b. Therefore, the width W of the terminal placement surface49may be reduced while a certain area is maintained for each terminal46,48. Thus, the size of the inkjet head4may be reduced in the same dimension as width W. Especially, when the channeled member21is formed by etching silicon, increase in the size of the channeled member21may be directly linked to increase in costs. Therefore, reduction of costs by reducing the width W of the terminal placement surface49may be effective.

In the example embodiment, the terminal placement surface49includes an inclined surface on an inner wall surface of the cavity36disposed between the channeled member21and the cover member23. With such a structure, when the COF24and the terminals46,48provided on the terminal placement surface49are bonded, an excess of the conductive bonding material having fluidity, e.g., conductive adhesive or solder, may flow down onto the bottom surface of the cavity36. Therefore, such a problem, e.g., a short-circuit, that may be caused by a buildup of the excessive conductive bonding material at the peripheries of the terminals46,48may be reduced.

To bond the COF24onto the terminal placement surface49, the COF24may be pressed against the terminal placement surface49while the COF24is being heated using a, fixture, e.g., a jig55, that may comprise a heater. In cases where the anisotropic conductive adhesive is used for bonding the COF24and the terminals46,48, insufficient force of pressing the COF24may cause the reduced reliability of electrical connection between the terminals of the COF24and the terminals46,48because the conductive particles might not electrically interconnect the terminals of the COF24and the terminals46,48. Therefore, in some cases, the COF24may be pressed against the terminal placement surface49comprising an inclined surface in a normal direction of the terminal placement surface49. In examples where the anisotropic conductive adhesive is used for bonding the COF24, the COF24may need to be firmly pressed against terminal placement surface49. As the COF24is pressed against the terminal placement surface49comprising an inclined or curved surface in its the normal direction, the COF24may be firmly pressed against terminal placement surface49with relatively strong pressing pressure.

In examples where the terminal placement surface49is provided on an inner wall surface of the cavity36, the COF24may sometimes be difficult to press against the terminal placement surface49in the normal direction thereof. In the example embodiment, the corners of the upper ends of the wall portion53of the cover member23defining the cavities36may be chamfered to form the inclined surface53a, as depicted inFIG. 4A. As depicted inFIG. 5, the inclined surface53amay be disposed at a portion of the open end of the cavity36, e.g., at an edge of an opening of the cavity36, on a side opposite to the terminal placement surface49. In such examples, the inclined surface53adoes not interfere with a virtual line VL extending along the normal direction of the terminal placement surface49. In other words, there exists at least one such virtual line normal to the terminal displacement surface49that does not intersect the inclined surface53a. The jig55used for pressing the COF24may be slantingly inserted into the cavity36along the inclined surface53a. Thus, the COF24may be pressed in the normal direction of the terminal placement surface49against the terminal placement surface49comprising an inclined surface, which may be disposed at an inner wall surface of the cavity36. Accordingly, the COF24may be reliably bonded to the terminals46,48on the terminal placement surface49. The inclined surface53aprovided on the wall portion53may correspond to a border portion. The inclined surface53amay extend in the sheet feeding direction. The shape of the border portion might not be limited to the shape of the inclined surface53aas depicted inFIG. 5. For example, a groove corresponding to each terminal46,48may be provided at the edge of the opening of the cavity36along the sheet feeding direction.

While the disclosure has been described in detail with reference to the specific embodiment thereof, this is merely an example, and various changes, arrangements and modifications may be applied therein without departing from the spirit and scope of the disclosure.

Example modifications in which alternative designs are described relative to the above-described example embodiment. Like reference numerals may be used for like corresponding components inFIGS. 6A-18Band a detailed description thereof with respect toFIGS. 6A-18Bmay be omitted herein.

First Example Modification

In a first example modification, the terminal placement surface49on which the terminals46,48are provided may be curved. For example, the terminal placement surface49may be convexly curved as depicted inFIG. 6A, or concavely curved as depicted inFIG. 6B.

If a terminal placement surface149is curved, the COF24may be pressed against the terminal placement surface149with the jig55that may have a curve shape corresponding to the terminal placement surface149, as depicted inFIG. 7. In this case also, it may be preferable that the COF24may be pressed against the terminal placement surface149in the normal direction of the terminal placement surface149. The normal direction of the terminal placement surface149that may be convexly curved as depicted inFIG. 6A, may be a direction perpendicular to a tangent plane56aat the top of the curved surface. The normal direction of the terminal placement surface149that may be concavely curved as depicted inFIG. 6B, may be a direction perpendicular to a tangent plane56bat the bottom of the curved surface.

When the terminal placement surface149is curved, an area of the terminal placement surface149may further be increased as compared with the inclined surface in the above-described example embodiment. In the above-described example embodiment, the terminal placement surface149may be inclined with respect to the vibration plate40, but the terminal placement surface149itself may be flat. When the terminal placement surface149itself is curved as in the example modification, it may be difficult to press the COF24against the terminal placement surface149with uniform force, leading to a difficult bonding operation. As compared with the convexly curved terminal placement surface149inFIG. 6Aand the inclined terminal placement surface149inFIG. 4A, the concavely curved terminal placement surface149inFIG. 6Bmay be more readily formed by etching the base material. Therefore, a concavely curved surface may be more readily formed than the inclined surface or the convexly curved surface.

When the normal direction of the curved terminal placement surface149is parallel to the surface40aof the vibration plate40(e.g., the tangent plane of the curved surface is perpendicular to the vibration plate40), it may be difficult to bond the COF24to the terminal placement surface149from above (e.g., a direction perpendicular to the vibration plate40). Therefore, it may be preferable that the normal direction of the terminal placement surface149might not be parallel to the surface40aof the vibration plate40.

To simplify the description of the disclosure, the following example modifications are described in connection with one of the inclined and curved terminal placement surfaces. Even so, the disclosure may be applied to the other one of the inclined and curved terminal placement surface, unless otherwise specified.

The terminal placement surface149may comprise not only the inclined surface or the curved surface, but also may comprise a surface parallel to the surface40aof the vibration plate40in addition to the inclined surface or the curved surface.

Second Example Modification

As depicted in the example modification shown inFIGS. 8A and 8B, a terminal placement surface249includes a first terminal placement surface249aand a second terminal placement surface249b. Each of the first terminal placement surface249aand the second terminal placement surface249bmay extend in the sheet feeding direction. The first terminal placement surface249amay be inclined with respect to the scanning direction. The second terminal placement surface249bmay be parallel to the surface40aof the vibration plate40. An end of the first terminal placement surface249ain the scanning direction may be connected to the second terminal placement surface249b. In another embodiment, the first terminal placement surface49amay be curved.

In the example ofFIG. 8A, the second terminal placement surface249bis connected to the lower end of the first terminal placement surface249a, which may be the inclined surface. The second terminal placement surface249bmay be disposed at a flat bottom surface of the cavity36. In the example ofFIG. 8B, the second terminal placement surface249bmay be connected to the upper end of the first terminal placement surface249a, and the second terminal placement surface249bmay be disposed at the surface40aof the vibration plate40.

In this example, the terminal placement surface249includes the second terminal placement surface249bparallel to the surface240aof the vibration plate40, in addition to the first terminal placement surface249a, which may be the inclined surface or the curved surface. Therefore, when external force is applied to the COF24in a direction in which the COF24is separate from the terminal placement surface249, directions in which the COF24is likely to be separate or removed from the first terminal placement surface249aand the second terminal placement surface249bmay be different from each other. Accordingly, the COF24disposed on the inclined or curved first terminal placement surface249aand the second terminal placement surface249bparallel to the surface40amay be more difficult to be removed when external force is applied to the COF24in a direction in which the COF24is separate from the terminal placement surface249, as compared with a case in which the first terminal placement surface249aand the second terminal placement surface249bare provided on the same plane and directions in which the COF24is likely to be removed from the first terminal placement surface249aand the second terminal placement surface249bare the same.

In the example shown inFIGS. 8A and 8B, one terminal246for the individual electrode42is provided over the first terminal placement surface249aand the second terminal placement surface249b. When the first terminal placement surface249acomprising the inclined surface or the curved surface might not ensure the sufficient area for the terminal246, the second terminal placement surface249bparallel to the vibration plate40may be provided.

Third Example Modification

In a third example modification, a terminal placement surface349includes a first terminal placement surface349aand a second terminal placement surface349b. In this example, terminals346for the individual electrodes42may be provided separately for the first terminal placement surface349aand the second terminal placement surface349b, as depicted inFIGS. 9A-10. In the example ofFIG. 10, an array of first terminals346a, for the individual electrodes42disposed at the first terminal placement surface349a, and an array of second terminals346b, for the individual electrodes42disposed at the second terminal placement surface349b, may be arranged along the nozzle arrangement direction in which the terminal placement surfaces349a,349bextend. In some such embodiments, the terminals346disposed at the first terminal placement surface349aand the second terminal placement surface349bmight not align in the scanning direction. In an example ofFIG. 10, the terminals346for the individual electrodes42may be densely disposed with a certain distance ensured between the adjacent first terminal346aand second terminal346bwhile risk of a short circuit or ion migration is at least reduced. The first terminals346afor the individual electrodes42disposed at the first terminal placement surface349a, and the second terminals346bfor the individual electrodes42disposed at the second terminal placement surface349b, may be arranged in any manner without being limited to the zigzag or staggered manner.

When the terminals346for the individual electrodes42are disposed on the first terminal placement surface349aand the second terminal placement surface349b, one COF24may be bonded to both of the first terminal placement surface349aand the second terminal placement surface349b, as depicted in the example ofFIG. 9A. In another embodiment, one COF24may be bonded to each of the first terminal placement surface349aand the second terminal placement surface349b, as depicted inFIG. 9B. More specifically, a first flexible wiring board24A, may be bonded to the terminals346for the individual electrodes42disposed on the first terminal placement surface349a. A second flexible wiring board24B, may be bonded to the terminals346for the individual electrodes42disposed on the second terminal placement surface349b.

When the terminals346for the individual electrodes42are densely arranged and corresponding terminals are arranged on one COF24, the terminals of the COF24may be densely arranged, which may utilize special patterning and may lead to increase in costs. When the COFs24A and24B are employed to connect to the terminal placement surfaces349a,349b, respectively, as depicted inFIG. 9B, density of the terminals on the COFs24A and24B may be reduced. Therefore, a general-purpose COF as discussed herein may be used to reduce costs.

Fourth Example Modification

In a fourth example modification, different types of terminals may be disposed on a first terminal placement surface449aand a second terminal placement surface449b.

For example, as depicted inFIG. 11, first contact terminals446, which may be connected to first electrodes442, may be disposed on the first terminal placement surface449a. Second contact terminals448, which may be connected to the common electrode43, may be disposed on the second terminal placement surface449b.

It may be difficult to press the COF24from a direction normal to a plate surface of vibration plate40against the first terminal placement surface449acomprising an inclined surface (or a curved surface), as compared with the second terminal placement surface449b, which may be parallel to the vibration plate40. Therefore, it is possible that the electrical resistance of a connecting portion between the COF24and the terminals on the first terminal placement surface449amay increase. Potential of the common electrode43that may be common to the piezoelectric elements44may be kept at a reference potential (e.g., ground potential). If the electrical resistance in a portion of a conduction path connected to the common electrode43is increased, the potential of the common electrode43may readily fluctuate from the reference potential under the influence of a voltage drop. In this respect, the second contact terminals448for the common electrode43may be disposed on the second terminal placement surface449bagainst which the COF24may be firmly pressed.

Fifth Example Modification

In a fifth example modification, a further illustrated variation is shown in which, terminals546,548may be arranged at positions opposite to those ofFIG. 11(in the fourth example modification). In other words, as depicted inFIG. 12, a first contact terminals548for the common electrode43, may be disposed on a first terminal placement surface549aand a second contact terminals546for an individual electrodes542, may be disposed on a second terminal placement surface549b.

It may be difficult, in some cases, to press the COF24against the first terminal placement surface549aincluding an inclined surface (or a curved surface), as compared with pressing a COF24against the second terminal placement surface549b. This may mean that reliability of electrical connection between the terminals of the COF24and the terminals48disposed on the first terminal placement surface549a, may be reduced or become lower as compared with the electrical connection between the terminals of the COF24and the terminals46disposed on the second terminal placement surface549b. If the second contact terminal546for an individual electrode542and the COF24are electrically disconnected, the corresponding piezoelectric element44might not be driven. If the COF24and the common electrode43electrically connected via a plurality of the first contact terminals548, such a critical problem that the piezoelectric element44might not be driven might not occur, even if one of the first contact terminals548is electrically disconnected from the COF24. In this respect, it may be preferable that the second contact terminals546for the individual electrodes542may be disposed on the second terminal placement surface549bagainst which the COF24may be firmly pressed.

If the terminal placement surface549includes the first terminal placement surface549aand the second terminal placement surface549b, as in the second to fifth example modifications, it may be preferable that the COF24is pressed against the first terminal placement surface549aand the second terminal placement surface549bin their respective normal directions. For example, for the first terminal placement surface549acomprising an inclined surface, the jig55may be slantedly inserted into the cavity36, as depicted inFIG. 13A. A first bonding process may be performed in which the COF24may be bonded to the first terminal placement surface549aby pressing the COF24against the first terminal placement surface549ain a direction normal to the first terminal placement surface549ausing the jig55. For the second terminal placement surface549bparallel to the vibration plate40, the jig55may be inserted into the cavity36in the vertical direction, as depicted inFIG. 13B. A second bonding process may be performed in which the COF24may be bonded to the second terminal placement surface549bby pressing the COF24against the second terminal placement surface549bin a direction normal to the second terminal placement surface using the jig55. Thus, the COF24may be reliably bonded to each of the terminal placement surfaces549a,549bthat may have different inclination or shape. As depicted inFIGS. 13A and 13B, bonding of the COF24onto the first terminal placement surface549aand the second terminal placement surface549bmay be performed by two processes. In another embodiment, bonding of the COF24onto the terminal placement surfaces549a,549bmay be performed at one time using a jig that may comprise two pressing surfaces configured to press against each of the terminal placement surfaces549a,549bat one time.

A member used to form the terminal placement surface549and a shape of the member forming the terminal placement surface549may be modified, such that additional embodiments exist. Example ones of those embodiments are further described below, and in connection withFIGS. 14-19.

Sixth Example Modification

In a sixth example modification as depicted inFIG. 14, a wall portion53of the cover member23is omitted, such that a recess portion635formed in the channeled member21might not be divided into the two cavities36. In the sixth example modification in which the wall portion53is omitted an area of the opening of the recess portion635may be increased. Therefore, in such a configuration, the jig55may be readily inserted into the recess portion635.

Seventh Example Modification

In a seventh example modification, a terminal placement surface49is provided on a wall portion753of the cover member23that may define the two cavities36. For example, as depicted inFIG. 15A, the wall portion753may be disposed at a surface740aof the vibration plate40. The wall portion753may extend along a direction in which the piezoelectric elements44may be arranged (e.g., the nozzle arrangement direction), to divide the two arrays of the piezoelectric elements44. The wall portion753may comprise two side portions753awhose surfaces may be inclined. When the cover member23does not comprise the wall portion753, as depicted inFIG. 15A, a connecting portion752might not have to connect the seal portions51configured to cover the respective arrays of the piezoelectric elements44. The separate seal portions51may be provided.

As depicted in the example ofFIG. 15B, surfaces of side portions1753aof a wall portion1753are curved. InFIG. 15B, a cross section of the wall portion1753has a semi-elliptic shape. In another embodiment, a cross section of the wall portion1753may have, for example, a semicircular shape (e.g., a shape of a half of a circle). In the seventh example modification, the side portion1753aof the wall portion1753may refer to a portion of the wall portion1753disposed on each side thereof with respect to a vertical plane including the apex.

A surface of the side portion1753aprovided on the inclined surface (or the curved surface) may serve as a terminal placement surface1749. Each array of terminals1746,1748corresponding to the respective array of the piezoelectric elements44may be disposed on the respective terminal placement surface1749. In such a structure, each COF24may be bonded to the respective array of the terminals1746,1748disposed on the terminal placement surface1749of each side portion1753aof the wall portion1753, by pressing the COFs24at one time against the wall portion1753from above using such jig55as depicted inFIG. 15A. Thus, the bonding operation may be facilitated. In another embodiment, the COFs24may be bonded to the respective terminal placement surfaces1749in separate processes by pressing the COFs24using such jig55as depicted inFIG. 5against the respective side portions1753ain their normal direction. In the seventh example modification, the channeled member21might not comprise the recess portion35as in the above-described example embodiment (FIG. 4A), to make the terminal placement surface1749inclined or curved.

The terminal placement surface1749comprising an inclined surface or a curved surface may be disposed not only at the wall portion1753of the cover member23but also at a side wall of the seal portion51that may enclose or seal the piezoelectric elements44.

Eighth Example Modification

In an eighth example modification, and as compared to the seventh example modification of FIGS.14and15A-B, a wall disposed to divide the arrays of the piezoelectric elements44may be provided at the channeled member21or the vibration plate40. InFIG. 16, a wall portion858is shown as provided at the channeled member21.

Ninth Example Modification

In a ninth example modification, a cover member23configured to cover the piezoelectric layer41is omitted. In the example shown inFIG. 17, the cover member23is omitted fromFIG. 16of the eighth example modification. Unlike the above-described example embodiment, a terminal placement surface949inFIG. 17might not be disposed on an inner wall surface of the recess35defined by the channeled member21and the cover member23. A wider space may be provided around the terminal placement surface949, so that the COF24may be readily pressed against the terminal placement surface949including an inclined surface (or a curved surface). In another embodiment, the recess portion35at which the terminal placement surface949is disposed may be provided only in the channeled member21. When the recess portion35is provided only in the channeled member21, such a jig insertion portion as depicted inFIG. 5may be provided at a portion of the channeled member21that may define an edge of the opening of the recess portion35.

In the examples ofFIGS. 15-17, the terminal placement surface949may be disposed above the vibration plate40, e.g., at a position opposite to the pressure chambers33with respect to the vibration plate40in the direction perpendicular to the vibration plate40. Therefore, the COF24may be more readily bonded to the terminal placement surface949, as compared with a structure, as depicted inFIG. 4A, in which the terminal placement surface949may be disposed on the side of the pressure chambers33.

Tenth Example Modification

in a tenth example modification, a terminal placement surface1049may be provided separately from the channeled member21or the vibration plate40. As depicted in the example shown inFIG. 18A, a projection60comprising an inclined surface may be attached to the surface1040aof the vibration plate40. The inclined surface may serve as the terminal placement surface1049. As depicted in the example shown inFIG. 18B, a projection61including a curved surface is attached to the upper surface of the channeled member21. The curved surface may serve as a terminal placement surface2049. Thus, when the terminal placement surface2049is provided separately from the channeled member21or the vibration plate40, the terminal placement surface2049may be formed in various shapes without being subjected to restrictions of, for example, shapes of the channeled member21or the vibration plate40. Therefore, the terminal placement surface2049may have a high degree of flexibility in its shape.

Eleventh Example Modification

In an eleventh example modification, a drive element disposed at the vibration plate40is not be limited to the piezoelectric element44. In another embodiment, the drive element may include, for example, a thermal expansion element configured to expand with heat so as to deform the vibration plate40.

Twelfth Example Modification

In still further example modifications, the features of the present disclosure may be applied to other inkjet head configurations. For example, configurations may be used that eject ink using bubble formation within the pressure chamber(s) of an inkjet head4to eject ink, in addition to those disclosed above in which the inkjet head4is configured to eject ink by driving the piezoelectric elements44. As depicted in the example ofFIG. 19, an inkjet head1204includes a channeled member1221and a silicon substrate1240. The channeled member1221as shown includes nozzles1230configured to eject ink therefrom and pressure chambers1233configured to fluidly communicate with the nozzles1230. The silicon substrate1240may be connected to the channeled member1221to cover the pressure chambers1233. In such embodiments, the silicon substrate1240may include a manifold1232configured to fluidly communicate with the pressure chambers1233. The silicon substrate1240may include a surface1240athat may extend in the scanning direction. The channeled member1221may be connected to the surface1240a. The inkjet head1204may further comprise a base plate1201and a support plate1200. The base plate1201may be connected to the silicon substrate1240. The base plate1201may have an ink supply opening1231configured to be fluidly communicate with the manifold1232. The support plate1200may be connected to the base plate1201. The support plate1200may have an opening1200ain which the channeled member1221and the silicon substrate1240may be disposed.

The silicon substrate1240may comprise heaters1222that may oppose the nozzles1230in the vertical direction, terminals1246configured to electrically connect to the heaters1222and a terminal placement surface1249at which the terminals1246may be disposed. In this example embodiment, the heaters1222may correspond to example embodiments of drive elements, as that term is used herein. In some such embodiments, the terminal placement surface1249is inclined with respect to the surface1240a. A chip on film (“COF”)1224may be disposed on the support plate1200. A portion of the COF1224may be bonded to the terminals1246. A sealing agent1202may cover the portion where the COF1224and the terminals1246may be connected.

In such embodiments, as a voltage is applied via the COF1224and the terminals1246, the heater1222generates bubbles in ink in the pressure chambers1233opposing the heater1222in the vertical direction to eject ink from the nozzles1230.

In another embodiment, the terminal placement surface1249may include an inclined surface that may extend upward from the channeled member1221toward the support plate1200.

In the above-described embodiment and the example modifications, disclosure may be applied to an inkjet printer configured to eject ink onto a sheet to print, for example, an image. In another embodiment, disclosure may be applied to liquid ejection apparatuses that may have different usages than the image printing. For example, disclosure may be applied to a liquid ejection apparatus configured to eject a conductive liquid onto a substrate to form conductive patterns on a surface of the substrate. Furthermore, although the invention has been described based on example embodiments and variations, the embodiments of the invention facilitate the understanding of the invention and do not limit the invention. The invention can be changed or modified without departing from the spirit of the invention and the scope of the claims and the invention includes the equivalents thereof