Liquid ejecting head unit and liquid ejecting apparatus

A liquid ejecting head unit includes a plurality of heads having a nozzle surface in which nozzle openings that eject ink are provided; a cover head that protects the nozzle surfaces of the heads, and a cover that covers the heads and between the nozzle surfaces of each head, in which the cover has a conducting portion that conducts with the cover head of the head.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2013-070723 filed on Mar. 28, 2013, and Japanese Patent Application No. 2013-270546 filed on Dec. 26, 2013. The entire disclosure of Japanese Patent Application Nos. 2013-070723 and 2013-270546 are hereby incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a liquid ejecting head unit and a liquid ejecting apparatus, and, in particular, relates to an ink jet recording head unit and an ink jet recording apparatus that eject ink as a liquid.

2. Related Art

A liquid ejecting apparatus represented by an ink jet recording apparatus, such as an ink jet printer or plotter, includes a liquid ejecting head (below, referred to simply as a head) that ejects a liquid, such as ink, stored in a cartridge or a tank.

Lining up a plurality of nozzle openings in a single head and lengthening (increasing the number of nozzles) or increasing the density thereof is difficult. Therefore, a liquid ejecting head unit (hereinafter, simply referred to as a head unit) including a plurality of heads has been proposed (for example, refer to JP-A-2011-46144).

In the head unit, the metal components that configure the head may be charged due to static electricity from the recording medium such as a recording paper or from the outside, and thus there is concern of a piezoelectric element for providing pressure to the ink or a driver IC for driving the piezoelectric element being damaged.

Therefore, charging in the head is suppressed by electrically connecting each head to the carriage or the like of the ink jet recording apparatus.

However, because providing a conducting portion by which each head is grounded on the carriage is necessary, the space in which the conducting portion is arranged is necessary. Furthermore, the number of components necessary for the conducting portion increases according to the number of heads, and the cost increases.

Such problems arise not only in a head unit that includes an ink jet recording head that ejects ink, but similarly arise in liquid ejecting head units and liquid ejecting apparatuses that include a liquid ejecting head that ejects a liquid other than ink.

SUMMARY

An advantage of some aspects of the invention is to provide a liquid ejecting head unit and a liquid ejecting apparatus able to effectively prevent charging in the liquid ejecting head.

According to an aspect of the invention, there is provided a liquid ejecting head unit including a plurality of liquid ejecting heads including a liquid ejecting surface in which nozzle openings that eject a liquid are provided; a protective plate that protects the liquid ejecting surface of each liquid ejecting head, and a cover that covers between the liquid ejecting surfaces of each liquid ejecting head; in which the cover has a conducting portion that electrically conducts with the protective plate of the liquid ejecting head.

According to the aspect, by providing the conducting portion in the cover that protects the liquid ejecting head, the cover also serves a grounding function. In so doing, it is possible to achieve space savings and cost reductions by reducing the number of grounding members for grounding each liquid ejecting head. In this application, the term “ground” is not limited to connection to a grounding surface, but means setting to a predetermined reference potential.

It is preferable that the liquid ejecting head unit further include a holding member to which a plurality of the liquid ejecting heads is fixed and that, the liquid ejecting heads be grounded to the cover via the holding member. Thereby, even in a case in which conduction is not directly established between the liquid ejecting head and the cover, the liquid ejecting head and the cover can be grounded via the holding member.

It is preferable that the liquid ejecting head unit further include an elastic sealing member that seals between the protective plate and the cover; and a fixing member that fixes the cover and the holding member to be able to conduct with each other. Thereby, the transfer of foreign materials such as liquid from the exterior of the cover to the interior of the cover via a space between the protective plate and the cover can be suppressed, and damage due to shorting of electronic components of the liquid ejecting head can be suppressed.

It is preferable that the liquid ejecting head unit further include a plate spring-like grounding plate fixed to the holding member, and that the grounding plate contact the protective plate by being biased and conduct with the protective plate and the holding member. Thereby, the holding member and the protective plate can be made to conduct via the grounding plate. Since the grounding plate is formed in a plate spring shape, a state in which the grounding plate is in contact with the protective plate side is easily maintained, and the protective plate can more reliably conduct with holding member.

It is preferable that the cover include an outside member, a first groove forming member, and a second groove forming member between the outside member and the first groove forming member, a head opening by which the liquid ejecting surface of the liquid ejecting head is exposed be provided in the outside member, the first groove forming member and the second groove forming member, the outside member conduct with the first groove forming member, the fixing member fix the first groove forming member and the holding member to be able to conduct with each other, and the elastic sealing member be arranged at the groove portion in which the inner surface of the head opening is provided, and is interposed between the outside member and the first groove forming member. Thereby, the elastic sealing member can be easily fixed to the first groove forming member and the outside member.

It is preferable that the first groove forming member be formed to be thicker than the outside member and thinner than the second groove forming member, that the outside member and the first groove forming member each have a curved side surface portion, and that the second groove forming member be formed in a planar shape. Thereby, since the first groove forming member and the outside member are relatively thin, the members are easily formed curved. Because the thickest second groove forming member has a planar shape that is not bent, the width in the transport direction can be reduced.

It is preferable that the cover be attachable and detachable, and that the conducting portion abut on the protective plate by elastic deformation. Thereby, each liquid ejecting head can be set to a standard potential by simply attaching a cover.

It is preferable that a protrusion be provided at a position opposing a region abutted by the conducting portion of the protective plate on the liquid ejecting head or the protective plate. Thereby, contact between the conducting portion and the protective plate can be more reliably established.

According to another aspect of the invention, there is provided a liquid ejecting apparatus including a liquid ejecting head unit according to the above aspects.

According to the aspects, a liquid ejecting apparatus able to prevent charging in the liquid ejecting head, and able to save space and lower costs is provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, embodiments of the present invention are explained in detail based on drawings. The ink jet recording head unit is an example of a liquid ejecting head unit, and is simply referred to as a head unit. The ink jet recording head is one example of a liquid ejecting head, and is simply referred to as a head.

FIG. 1is a schematic perspective view of the head unit according to the present embodiment,FIG. 2is a bottom view of a head unit according to the embodiment, andFIG. 3is a cross-sectional view taken along line III-III inFIG. 2.

The head unit1includes a plurality of heads10fixed to a holding member30, a cover head16that is an example of a protective plate that protects a nozzle surface15that is an example of a liquid ejecting surface of the head10, and a cover60that covers between the head10and the nozzle surface15of each head10.

The head unit1according to the embodiment has six heads10fixed to one holding member30. Two rows of a head row10A and a head row10B in which three heads10are arranged in line in the Y direction are formed. The head row10A and the head row10B are arranged to oppose one another with the holding member30interposed, and the relative positions of between each head10are regulated and fixed to the holding member30. In the embodiment, the nozzle surface15by which each head10discharges ink is set to the XY plane, and the direction in which the heads10are arranged in line is set to the Y direction. That is, the head row10A and the head row10B are formed of a plurality of heads10arranged in line in the Y direction. The head row10A and the head row10B are arranged in parallel in the X direction orthogonal to the Y direction. A direction orthogonal to the XY plane is set as the Z direction.

The head10will be described in detail usingFIGS. 4 to 6.FIG. 4is a front view of the head,FIG. 5is a top view of the head, andFIG. 6is a bottom view of the head.

The head10includes a head main body12in which the nozzle openings11are provided, and a flow channel member13fixed to the surface of the head main body12on the opposite side to the nozzle openings11.

The head main body12includes nozzle rows14. The surface on which the nozzle rows14are provided is set as the nozzle surface15(liquid ejecting surface).

The nozzle row14refers to a plurality of nozzle openings11arranged in line in the Y direction (first direction). In the embodiment, nozzle row14aand nozzle row14bin which nozzle openings11are aligned linearly in the Y direction are arranged in two rows. The nozzle openings11of the one nozzle row14aare formed shifted by a half pitch from the nozzle openings11of the other nozzle row14b. Either of the nozzle rows14aand14bejects the same type of liquid, and the two nozzle rows14aand14bsubstantially form one nozzle row14. In the invention, the nozzle row14formed as substantially one row is referred to as a nozzle row. In so doing, the resolution may be doubled. The nozzle row may have a form in which three or more rows substantially configure one row. Naturally, only one nozzle row may also be included. Two or more nozzle rows may be included, and each nozzle row may eject different types of liquid, and in this case, a plurality of nozzle rows are included.

The cover head16that is an example of a protective plate that protects the nozzle surface15is provided in the head main body12. The cover head16is configured from an opening portion16aby which the nozzle row14is exposed, and a frame portion16bthat defines the opening portion16a. The frame portion16bprotects the nozzle surface15by covering the peripheral edge portion of the nozzle surface15.

Although not specifically shown in the drawings, a pressure generating chamber that configures a portion of a flow channel that communicates with the nozzle opening11, and a pressure generating unit by which a pressure change is generated in the pressure generating chamber and causing ink to be ejected from the nozzle opening are provided inside the head main body12.

Although the pressure generating unit is not particularly limited, examples thereof using a piezoelectric element in which a piezoelectric material that exhibits an electromechanical conversion function is interposed between two electrodes, or having a heat generating element arranged in the pressure generating chamber and ejecting droplets from the nozzle opening11through a bubble generated with the heat from the heat generating element, or in which static electricity is generated between a diaphragm and an electrode and droplets are caused to be ejected from the nozzle opening11by the diaphragm being deformed due to the electrostatic force may be used. A flexural oscillation-type piezoelectric element in which a lower electrode, a piezoelectric material and an upper electrode are layered from the pressure generating chamber side are caused to flexurally deform, or a longitudinal oscillation-type piezoelectric element in which a piezoelectric material and an electrode forming material are alternately layered and caused to expand and contract in the axial direction, or the like may be used as the piezoelectric element.

A flow channel member13supplies ink from outside to the head main body12or discharges ink from the head main body12to the outside. The flow channel member13is fixed to the surface of the head main body12on the side opposite to the nozzle openings11. An ink flow channel connection portion17and a connector18are provided on the upper surface of the flow channel member13.

The ink flow channel connection portion17is a part that connects an internal flow channel of the flow channel member13to an external flow channel. The connector18is a part by which an electronic signal, such as a print signal from the outside, is supplied, and is connected to a connection wiring19. The connection wiring19is a member having flexibility, such as FPC that transmits the print signal.

A fixing portion20that protrudes in the Y direction is provided on the flow channel member13. The fixing portion20is formed in a plate shape nearly parallel to the YZ plane, and is provided at the approximate center portion in the X direction of the flow channel member13. A fixing screw insertion hole22penetrating in the thickness direction is provided in the fixing portion20.

The holding member will be described in detail usingFIGS. 7 to 10.FIG. 7is a front view of the holding member,FIG. 8is a top view of the holding member,FIG. 9is a bottom view of the holding member, andFIG. 10is a cross-sectional view taken along line X-X inFIGS. 8 and 9.

The holding member30is a member that holds the head row10A and the head row10B by being formed elongated in the Y direction. The holding member30includes a base portion31disposed on the upper portion of the holding member, and a holding portion forming portion48disposed on the lower portion of the holding member.

The base portion31is formed in a plate shape having a surface nearly parallel to the nozzle surface15(refer toFIG. 5), and positioned on the upper surface side of each head10. A connection flow channel32penetrating in the thickness direction is provided in the base portion31. The connection flow channel32is fit to the ink flow channel connection portion17(refer toFIG. 3) of the head10. Although not specifically shown in the drawings, ink is supplied from a liquid storage unit such as an ink cartridge to the connection flow channel32via a tube or the like. Then, the ink supplied to the connection flow channel32is supplied to the ink flow channel connection portion17and supplied to the head main body12. In the embodiment, two connection flow channels32are provided in the base portion31for each head10.

A connection wiring concavity33is provided in the side surface (surface parallel to the YZ plane) of the base portion31. The connection wiring19connected to the head10is accommodated in the connection wiring concavity33.

The holding portion forming portion48is a member in which a plurality of holding portions40is formed. In the embodiment, the holding portion forming portion48is formed long in the Y direction and short in the X directions and has a plate form erected on the base portion31, and a plurality of holding portions40to which each head10is attached is formed on both side surfaces orthogonal to the Y direction. The head row10A and the head row10B are arranged at both sides of such a plurality of holding portions40(holding portion forming portion48) in the Y direction and fixed to the holding member.

The holding portion40is a region from the holding member30to which each head10is attached, and in the embodiment, is a region that includes a head attachment surface41and an accommodation portion42. The head attachment surface41is a region to which the fixing portion20of the head10is attached, and the accommodation portion42is a space in which the head main body12of the head10and the flow channel member13are accommodated. In the embodiment, the head attachment surface41and the accommodation portion42are formed as below.

The holding portion forming portion48includes a plurality of thick portions43that are relatively thick in the X direction, and thin portions44that are formed to be thinner than the thick portions43. The thick portion43is a site protruded from the thin portion44in the X direction. At both side surfaces (side surface44a, side surface44b) of the holding portion forming portion48, the region between the adjacent thick portions43in the Y direction becomes the accommodation portion42, and the surface (surface orthogonal to the Y direction) of the thick portion43becomes the head attachment surface41.

The thick portions43on the side surface44aand the side surface44bof the holding portion forming portion48are arranged in a zig-zag pattern along the Y direction. That is, the thick portion43on the side of the side surface44a(side surface44b) of the holding portion forming portion48is provided such that the position thereof in the Y direction overlaps the accommodation portion42of the side surface44b(side surface44a) side. Although described in detail later, by forming holding portions40that include such accommodation portions42, the holding portions40are arranged in a zig-zag pattern along the Y direction, and each head10held by each holding portion40is arranged in zig-zag pattern.

On the head attachment surface41, a fixing screw hole46that penetrates in the width direction (X direction) of the thick portion43is provided. The fixing screw hole46, which will be described in detail later, is a screw hole to which the fixing screw inserted in the fixing screw insertion hole22(refer toFIG. 3) of the head10is screwed. The head10is fixed to the head attachment surface41by the fixing screw.

In addition, the accommodation portion42positioned to one surface side from both side surfaces (side surface44aside, side surface44bside) of the holding portion forming portion48is provided to overlap and oppose the head attachment surface41(thick portion43) positioned on the other surface side in the Y direction. Meanwhile, one head attachment surface41is provided between two adjacent accommodation portions42in the Y direction. Each fixing portion20of two heads10respectively accommodated in the adjacent accommodation portions42is fixed to one head attachment surface41.

In the embodiment, at both side surfaces of the respective holding portion forming portion48, three accommodation portions42are provided corresponding to the head row10A and the head row10B, and a head attachment surface41is provided at both end sides of each accommodation portion42in the Y direction. Although described in detail later, by attaching each head10to holding portion40having such a head attachment surface41and accommodation portion42, the head row10A and the head row10B are arranged and opposed with the holding portion40interposed, and are arranged in a zig-zag pattern along the Y direction.

The holding member30is integrally formed with a base portion31and a holding portion forming portion48having a plurality of holding portions40. By being integrally formed in this way, the rigidity of the base portion31and the holding portion40is improved. Naturally, the base portion31and the holding portion forming portion48may each be formed as separate members, and the holding member30may be formed by bonding these. In addition, although the material of the holding member30is not particularly limited, it is preferable that a material having rigidity, such as SUS, be used.

The head attached to the holding member will be described in detail usingFIGS. 11 to 13.FIG. 11is a front view of the head unit,FIG. 12is a bottom view of the head unit, andFIG. 13is a cross-sectional view taken along line XIII-XIII inFIG. 11.

The head row10A and the head row10B are arranged in a zig-zag pattern along the Y direction with the holding portion40of the holding member30interposed. That is, on both side surfaces of the holding member30, each head10that configures the head row10A and the head row10B is fixed to each holding portion40. More specifically, the heads10are fixed as below.

For each head10, the fixing portion20abuts the head attachment surface41and head main body12and the flow channel member13are accommodated in each accommodation portion42. In addition, the fixing screw51is inserted in the fixing screw insertion hole22provided in the fixing portion20, and screwed into the fixing screw hole46provided in the head attachment surface41. The fixing screw51is not screwed into the fixing screw insertion hole22, and the fixing portion20is fixed to the head attachment surface41in the head portion.

In the head10fixed in this manner, an ink flow channel connection portion17is fitted with a connection flow channel32and communicates with the inner portion. In so doing, although not specifically shown in the drawings, ink is supplied from an ink storage unit, such as an ink cartridge, to the connection flow channel32via a tube or the like, and further supplied to the head main body12via the ink flow channel connection portion17.

The connection wiring19connected to the head10is accommodated in a connection wiring concavity33provided in the base portion31, and the end portion thereof is connected to a control device (not shown) that supplies a driving signal. By providing the connection wiring concavity33in the base portion31, it is possible to accommodate the connection wiring19without protruding from the side surface of the base portion31.

In the embodiment, the relative positions of each of the heads10to one another are positioned to have predetermined arrangement. Here, the relative positions of each of the heads10to one another indicates the arrangement of each head10such that the nozzle row14of each head10forms a single continuous nozzle row unit, and arranging each head10in a zig-zag pattern in the Y direction.

Arranging each head10in a zig-zag pattern in the Y direction indicates the arrangement as below. That is, the nozzle opening11(one or a plurality thereof) that is positioned at the end portion side of the head10of the head row10A (head row10B) in the Y direction is arranged so that the position in the Y direction overlaps the nozzle opening11of the head10of the head row10B (head row10A).

Thus, the nozzle rows14are made continuous by the nozzle rows14between each head10being partially overlapped in the Y direction, and a nozzle row unit that forms the overall maximum printing width is configured. That is, the nozzle row unit indicates the nozzle rows14of all of the heads10of the head unit1being made continuous.

For the head unit1including each head10for which the relative positions are regulated as described above, ink is supplied from an ink cartridge not shown in the drawings to each head10, and ink droplets are ejected from the nozzle openings11based on the driving signal from a control device.

The cover60will be described in detail usingFIGS. 14 to 16B.FIG. 14is a top view of the cover,FIG. 15is a bottom view of the cover, andFIGS. 16A and 16Bare cross-sectional views taken along line XVIA-XVIA, XVIB-XVIB inFIG. 14.

The cover60covers between the head10and the nozzle surface15of each head10. The cover60according to the embodiment includes two cover portions61A and61B that are long in the Y direction bonded together. In a case in which the each of the cover portion61A and cover portion61B are not distinguished, they are referred to as a cover portion61.

The cover portion61includes a bottom plate63in which a plurality of opening portions62is formed, and a side plate64perpendicular to the bottom plate63. The cover portion61according to the embodiment is formed from a metal plate, such as SUS, and the bottom plate63and the side plate64are formed by folding back both ends of the metal plate along a straight line parallel to the Y direction.

A plurality of opening portions62is formed along the Y direction in the bottom plate63. In the opening portion62, the nozzle surface15of the head10is formed at a predetermined position so as to be exposed.

For each cover portion61, the side plates64are bonded to one another, and a single cover60is configured. A notch portion65and a conducting portion66are formed in the side plates64bonded to one another. The side plate64bonded to the cover portion61B of the cover portion61A is also referred to as a side plate64a. The side plate64bonded to the cover portion61A of the cover portion61B is also referred to as a side plate64b.

A plurality of notch portions65are formed in the cover portion61A by notching a part of the side plate64a. The notch portions65are formed so as to be positioned to the side of each opening portion62of the cover portion61A. Similarly, a plurality of notch portions65are formed in the cover portion61B by notching a part of the side plate64b. The notch portions65are formed so as to be positioned to the side of each opening portion62of the cover portion61B.

On the cover portion61A, a plurality of conducting portions66formed so that the upper end thereof becomes the free end and separated from the side plate64ais erected on the bottom plate63. Each conducting portion is arranged so as to oppose the notch portion65formed in the side plate64bof the other side cover portion61B. That is, the side plate64a, notch portion65, and conducting portion66are formed in the cover portion61A lined up in substantially the same plate (YZ plane).

Similarly, on the cover portion61B, a plurality of conducting portions66formed so that the upper end thereof becomes the free end and separated from the side plate64bis erected on the bottom plate63. Each conducting portion is arranged so as to oppose the notch portion65formed in the side plate64aof the other side cover portion61A. That is, the side plate64b, notch portion65, and conducting portion66are formed in the cover portion61B lined up in substantially the same plate (YZ plane).

As shown inFIGS. 16A and 16B, the conducting portion66of the cover portion61B (cover portion61A) is arranged so as to oppose the notch portion65of the cover portion61A (cover portion61B), and the cover60is configured by bonding the side plate64aand the side plate64bto one another.

Each conducting portion66formed on the cover60includes a bent portion66athat is bent. The bent portion66ais a site that conducts by contacting the cover head16of the head10.

The cover60with such a configuration is attached to the holding member30to which the head10fixed, as shown inFIGS. 1 to 3.

More specifically, the bottom plate63of the cover60covers the nozzle surface15side of the head10, the side plate64covers the side surface of the head10and the side plate64is fixed to the holding member30.

The opening portion62formed in the bottom plate63of the cover60is positioned so as to oppose the nozzle surface15of each head10, and the nozzle surface15is exposed from the opening portion62.

In a state in which the cover60is not attached, as shown inFIG. 12, a step difference in the Z direction occurs between the nozzle surfaces15of the heads10. That is, although the nozzle surfaces15of each head10are positioned in substantially the same plane, the head main body12, fixing portion20or the like therebetween are not in the same plane in the Z direction as the nozzle surfaces15.

Meanwhile, as shown inFIG. 2, in a state in which the cover60is attached, the bottom plate63covers between the nozzle surfaces15of each head10. In so doing, the bottom surface of the head unit1, other than the opening portions62, becomes flush.

Thereby, by making the bottom surface of the head unit1more flush than the cover60, it is possible to reduce disturbance to the air flow in the bottom surface side of the head unit1during printing. Because such air flow disturbance is reduced, it is possible for ink droplets ejected from the head10to be more precisely landed at a predetermined position.

Additionally, in a case in which the cover60is not attached, disturbance of the air flow occurs between the head unit1and a recording medium, such as paper, by the step difference formed between the nozzle surfaces15of the heads10during printing. When such an air flow disturbance occurs, the ejection direction of the ink droplets ejected from the head10is disturbed, and the landing positions are shifted.

The conducting portions66(bent portion66a) provided in the cover60contact and conduct with the cover head16of the head10. More specifically, the side plate64aand the side plate64bof the cover portion61A and the cover portion61B enter between the head row10A and the head row10B. The conducting portion66of the cover portion61A contacts the cover head16of the head10on the head row10B side. Similarly, the conducting portion66of the cover portion61B contacts the cover head16of the head10on the head row10A side.

By abutting the bent portion66aof the conducting portion66on the cover head16, the bent portion66ais pressed towards the inside of the cover portion61. That is, the bent portion66ais elastically deformed to the inside of the cover portion61, and the counterforce of the bent portion66aacts on the cover head16. In so doing, it is possible for conduction to be established by the conducting portion66and the cover head16being in more reliable contact.

Although not specifically shown in the drawings, a grounding portion connected to the ground is provided on the carriage of the ink jet recording apparatus in which the head unit1is mounted. The grounding portion is configured to be able to contact the holding member30of the head unit1mounted on the carriage.

Accordingly, the cover head16of each head10is grounded by conducting with the grounding portion of the carriage via the cover60(each conducting portion66). Thereby, each head10is electrically connected to the carriage via the cover head16or the cover60. Thereby, each head10is not charged or a charged electrical charge is discharged. Thereby, it is possible to suppress a piezoelectric element or the like of the head10, or a driver IC or the like for driving the piezoelectric element or the like from being damaged.

In the head unit1, the cover60functions as a common grounding member by which the plurality of heads10are grounded.

Accordingly, it is not necessary to provide a plurality of grounding portions by which each head10is grounded on the carriage. In so doing, it is possible to reduce the space in which components by which conduction is established between each head10and the carriage. Since a grounding portion corresponding to the cover60is not provided on the carriage, it is possible to reduce costs by suppressing the number of components.

Because the cover60serves a ground function by which each head10is grounded and a rectifying function that suppresses air flow disturbances during printing, it is possible to reduce the cost of components, and the time and effort or costs associated with manufacturing compared to a case in which these functions are separately configured.

Furthermore, the cover60is attachable and detachable, the conducting portions66of the cover60are configured to conduct through contact with the cover head16. That is, the conducting portion66is not configured to conduct in a fixed manner through a fastening tool such as a screw. In so doing, it is possible for each head10to electrically conduct with the ground simply by attaching the cover60. In so doing, when the cover60is replaced, if the old cover60is removed, and a new cover60is attached, conduction is also achieved, it is therefore possible to reduce the time and effort associated with replacing the cover60.

As described above, the head unit1according to the embodiment serves a function of grounding the cover60by providing the conducting portions66on the cover60that protects the head10. In so doing, it is possible to achieve space savings and cost reductions by reducing the number of grounding members for grounding each head10.

Because conduction is much more reliably established between the conducting portions66of the cover60and each head10, a configuration as below may be used.FIG. 17is an enlarged cross-sectional view of the main portions of the head unit according to a modification example.

The cover head16is provided on the head10, and a protrusion12ais provided between the cover head16and the head10in the head main body12. The protrusion12ais provided at a position opposing the region A abutted by the conducting portion66(bent portion66a) of the cover head16.

If such a cover60is attached, one side surface of the region A is pressed to the bent portion66aof the conducting portion66. The head main body12side is bent and contacts the protrusion12aby the region A being pressed. The region A of the cover head16is also pressed to the bent portion66aside by the counterforce from the protrusion12a. As a result, it is possible to more reliably establish contact between the bent portion66aof the conducting portion66and the region A of the cover head16.

Such a protrusion12ais not limited to a case of being provided on the head10, and may be provided on the cover head16.

The head unit1according to Embodiment 1 has a configuration in which conduction is established between the conducting portion66provided on the cover60and the cover head16(protective plate) of the head10by direct contact; however there is no limitation to such a form. For example, the conducting portion66may indirectly conduct with the cover head16.

FIG. 18is a bottom view of the head unit according to Embodiment 2,FIG. 19is a cross-sectional view taken along the line XIX-XIX inFIG. 18,FIG. 20is an enlarged view of the main portions inFIG. 19, andFIG. 21is an enlarged view of the main portions inFIG. 20.

As shown the drawings, the head unit1A according to the embodiment includes a head10on which a cover head16A that covers the nozzle surface15is provided, a holding member30to which a plurality of the heads10is attached, a cover70that covers between the nozzle surfaces15, and a grounding plate80provided on the holding member30and establishing conduction by contacting the cover head16A.

First, the cover70will be described usingFIGS. 22 to 24.FIG. 22is a perspective view of a cover according to Embodiment 2,FIG. 23is an exploded perspective view of the cover according to Embodiment 2, andFIG. 24is a cross-sectional view taken along line XXIV-XXIV inFIG. 22.

As shown inFIGS. 22 and 23, the cover70is a member that covers outside the nozzle surfaces15and between each nozzle surface15, along with exposing the nozzle surface15of each head10. More specifically, the cover70includes a first groove forming member71, a second groove forming member72, and an outside member73.

The first groove forming member71includes a planar portion71athat covers between the nozzle surfaces15of each head10, and side surface portion71band side surface portion71cbent to the head10side and continuous with the planar portion71a. The side surface portion71bhas a side surface parallel to the XZ plane and has a fixing portion74fixed to the holding member30. The side surface portion71chas a side surface parallel to the YZ plane, and is formed to cover the side surface of each head10.

In the planar portion71a, an opening portion71dby which the nozzle surface15is exposed is provided in a region that opposes the nozzle surface15of each head10, and further, a conducting pin75protruded to the second groove forming member72side described later is provided on the surface of the planar portion71a. The fixing portion74is a planar site continuous with the side surface portion71band substantially parallel to the XY plane, and includes a fixing hole74athat penetrates in the Z direction.

The material of such a first groove forming member71is not particularly limited if the material is able to conduct. The first groove forming member71according to the embodiment, for example, is a planar member formed from a metal, the planar portion71a, side surface portion71band side surface portion71care formed by folding back the four sides thereof to one surface side, and the opening portion71dis formed by removing a portion of the planar portion71a.

The second groove forming member72is a plate-like member interposed between the first groove forming member71and the outside member73. The second groove forming member72has the same or a smaller planar shape as the planar portion71aof the first groove forming member71.

In the second groove forming member72, an opening portion72athat exposes the nozzle surface15is provided in a region that opposes the nozzle surface15of each head10. Although described in detail later, each opening portion72ais an opening by which the nozzle surface15is exposed by communicating with each opening portion71dof the first groove forming member71. Furthermore, in the second groove forming member72, a through hole72bpenetrating in the Z direction and into which the conducting pin75is inserted is formed.

The material of such a second groove forming member72is not particularly limited, and may be a material that is able to conduct, or may be an insulating material. The second groove forming member72according to the embodiment, for example, is a planar member formed from an insulating resin material, and the opening portion72ais formed by removing the region opposing the nozzle surface15.

The outside member73includes the planar portion73athat covers between the nozzle surfaces15of each head10, and the side surface portion73bcontinuous with the planar portion73athat is bent to the head10side. That is, the outside member73surrounds the planar portion73aand the side surface portion73b, is opened to the head10side, and has a box shape in which the planar portion73abecomes the bottom portion.

In the planar portion73a, an opening portion73cthat exposes the nozzle surface15is provided in a region that opposes the nozzle surface15of each head10, and further, a conducting hole73dthat is a through hole in which the conducting pin75is inserted is provided in the planar portion73a.

The material of such an outside member73is not particularly limited if the material is able to conduct. The outside member73according to the embodiment, for example, is a planar member formed from a metal, the planar portion73a, and the side surface portion73bare formed by folding back the four sides thereof to one surface side, and the opening portion73cand the conducting hole73dare formed by removing a portion of the planar portion73a.

As shown inFIG. 24, the second groove forming member72is bonded to one surface of the planar portion71aof the first groove forming member71, that is, to the surface on the opposite side in the Z direction to the side surface portion71c. Furthermore, the outside member73is attached to the first groove forming member71such that the second groove forming member72is interposed between the outside member73and the first groove forming member71. The form of bonding is not particularly limited, and, for example, the first groove forming member71, the second groove forming member72, and the outside member73may be bonded to one another with an adhesive, or may be bonded and fixed using a fastening tool, such as a screw.

Thereby, a head opening77in which each opening portion71d, opening portion72a, and opening portion73care communicated is formed by layering and integrating the planar portion71aof the first groove forming member71, the second groove forming member72and the planar portion73aof the outside member73as the cover70. Although described in detail below, one head10is inserted in the head opening77.

More specifically, the opening portion71dand the opening portion73care formed to have substantially the same shape, and the opening portion72ais formed to have a larger shape than that of the opening portion71dand the opening portion73c. Although not specifically shown in the drawings, when the opening portion71d, the opening portion72aand the opening portion73ccommunicate, the opening portion71dand the opening portion73care arranged overlapping in the opening portion72ain plan view (plane view from the Z direction).

A groove portion78is formed in the inner surface of such a head opening77. In the embodiment, the first groove forming member71having the opening portion71d, the opening portion72aand the opening portion73cwith the above-described shape, the second groove forming member72and the outside member73are formed by bonding.

An elastic sealing member76formed from an elastic material formed in a ring shape is fitted in the groove portion78. More specifically, the opening shape of the inner side of the elastic sealing member76is substantially the same shape as the opening portion71dand the opening portion73cin which the head10is inserted, and the profile of the elastic sealing member76is formed to be smaller than the opening portion72aof the second groove forming member72. The thickness of the elastic sealing member76is substantially the same as the thickness of the second groove forming member72. The elastic sealing member76is formed from an insulating material having elasticity, for example, a resin material.

The elastic sealing member76configures a part of the inner surface of the head opening77so as to be interposed between the first groove forming member71and the outside member73. In this way, since the elastic sealing member76is interposed between the first groove forming member71and the outside member73, it is possible to easily fix the elastic sealing member76. The outside member45serves to fix the elastic sealing member76as well as covering between the nozzle surfaces15of the head10. Therefore, it is possible to simplify the manufacturing of the cover70.

The conducting pin75provided on the first groove forming member71is inserted in the through hole72band fitted in the conducting hole73dof the outside member73. That is, the first groove forming member71contacts the outside member73via the conducting pin75. In the present embodiment, although the conducting pin75and the outside member73conduct with one another by being in contact, there is no limitation to such a form. For example, examples include a form in which the side surface of the cover70, that is, the side surface portion71cof the first groove forming member71and the side surface portion73bof the outside member73are brought into direct contact, and a form in which the side surface portion71cand the side surface portion73bare fixed with a conductive material.

By configuring the cover70as described above, the second groove forming member72is formed with an insulating material, and even if the outside member73is charged, although described in detail below, it is possible to discharge the charged electrical charge via the conducting pin75and the first groove forming member71.

As the form in which conduction is established between the outside member73and the first groove forming member71, there is no limitation to a case in which the above-described conducting pin75is used. For example, it is possible to adopt a form in which the second groove forming member72is formed with a conducting material and adhering is performed using a conductive adhesive.

A material is used that is thicker than the outside member73and thinner than the second groove forming member72for the first groove forming member71of the embodiment. The first groove forming member71and the outside member73are formed by such a material being bent, and the second groove forming member72is not bent. That is, the second groove forming member72that is relatively thickest of the members that configure the cover70is not bent, and the first groove forming member71and the outside member73that are relatively thinner than the second groove forming member72are bent.

Although the relationship between the thicknesses of the members that configure the cover70is not limited to the form described above, in this way, since the first groove forming member71and the outside member73are relatively thin, forming the members by bending is easily performed. Because the thickest second groove forming member72has a planar shape that is not bent, the width in the transport direction (X direction) may be reduced. If the second groove forming member72is bent and a side surface portion that corresponds to the side surface portion71cof the first groove forming member71is formed, the thick portion and the width in the X direction of the side surface portion is lengthened.

Although the outside member73that is furthest to the outside is formed to be relatively thinnest, since the first groove forming member71and the second groove forming member72are bonded, the rigidity of the cover70is improved overall.

The cover70with the above-described configuration covers the head10in a state in which the nozzle surface15of each head10is exposed in the head opening77and is fixed to the holding member30. Below, the head unit1A with such a cover70attached will be described in detail usingFIGS. 18 to 21.

As shown in the drawings, the first groove forming member71side of the cover70is attached to the holding member30. More specifically, the nozzle surface15of each head10fixed to the holding member30is inserted in the head opening77of the cover70from the first groove forming member71side (opening portion73cside). The side surface of the cover head16A of each head10contacts the elastic sealing member76provided inside the head opening77. Accordingly, the gap between the cover head16A and the head opening77is sealed by the elastic sealing member76. In so doing, it is possible to suppress the transfer of ink or mist from the exterior of the cover70to the interior head10via the gap, and to suppress shorting of the electrical components of the head10.

The opening portion16aof the cover head16A and the surface (surface on the side opposite to the holding member30in the Z direction) of the frame portion16bare substantially flush with the surface of the outside member73of the cover70.

Although not shown in the drawings, each nozzle surface15, while contacting a blade-like wiping member or the like made of rubber, performs cleaning (wiping) that removes ink or foreign materials attached to the surface by relatively moving in the XY plane.

Accordingly, it is possible to clean the opening portion16aof the cover head16A, the surface of the frame portion16band the surface of the outside member73when cleaning simply by the head unit1A relatively moving with respect to the wiping member in the XY plane. As described above, since the gap between the cover head16A and the head opening77is sealed with the elastic sealing member76, it is possible to suppress the infiltration of ink or mist and the like from the gap, and to suppress shorting of the electronic components of the head10even during cleaning.

If the surface of the outside member73protrudes further to the opposite side to the holding member30in the Z direction than the opening portion16aof the cover head16A and the surface of the frame portion16b, a mechanism is necessary for moving the wiping member in the Z direction in order to contact the nozzle surface15.

The fixing portion74formed on the first groove forming member71of the cover70contacts the top surface40aof the holding portion40of the holding member30, and is fixed with a screw79that is an example of a fixing member. The top surface40aof the holding portion40referred to here is the surface of the nozzle surface15side in the Z direction.

The screw79is formed from a conductive metal material. As described above, the first groove forming member71conducts with the outside member73via the conducting pin75. Accordingly, the entire cover70including the outside member73conducts with the holding member30via the screw79.

Meanwhile, the cover70only contacts the head10by the elastic sealing member76, and does not contact the head10at other sites. Since the elastic sealing member76is formed from an insulating material, the head10does not conduct through direct contact with the cover70. That is, the cover70does not directly conduct with the head10, and directly conducts with the holding member30.

The head10according to the embodiment conducts with the holding member30rather than the cover70via the grounding plate80. Here, the grounding plate80will be described usingFIG. 25andFIG. 26.FIG. 25is a perspective view of the grounding plate according to Embodiment 2, andFIG. 26is a plan view of the grounding plate provided on the holding member according to Embodiment 2.

The grounding plate80is a plate spring-like member fixed to the holding member30. More specifically, the grounding plate80is fixed to the top surface40aof the holding portion40of the holding member30, and has a plate-like attachment portion81long in the Y direction. An insertion hole83penetrating in the thickness direction is provided in the attachment portion81. A fixing member such as a screw is inserted in the insertion hole83.

The grounding plate80has two plate-like plate spring portions82continuous from the long side of the attachment portion81, that is the side parallel to the Y direction, and substantially parallel to the YZ plane. The two plate spring portions82are biased in mutually separating directions (X direction).

The material of such a grounding plate80is not limited, if the material is able to conduct. The grounding plate80according to the embodiment, for example, is a planar member formed from a metal, a plate spring portion82is formed by folding back two sides thereof parallel in the Y direction to one surface side, and the insertion hole83is formed by removing a portion of the attachment portion81.

Such a grounding plate80is fixed (refer toFIG. 19andFIG. 26) to the holding portion40of the holding member30so that the plate spring portion82between the two rows, head row10A and head row10B, becomes parallel. The fixing unit of the grounding plate80is not particularly limited. In the embodiment, a screw hole (not shown) is provided in the top surface40aof the holding portion40of the holding member30, and the grounding plate80is fixed to the holding member30by a screw (not shown) being inserted in the insertion hole83and screwed into the screw hole.

As shown inFIG. 19andFIG. 20, the cover head16A attached to each head10includes a bent portion16cthat is bent such that a portion of the side surface facing the holding portion40side of the holding member30protrudes to the holding portion40side. The plate spring portion82of the grounding plate80described above contacts the bent portion16cside by being biased.

In this way, the grounding plate80is directly fixed to the holding member, and also directly contacts the cover head16A. In Embodiment 1, the cover head16A contacts the peripheral edge portion of the nozzle surface15as described. Accordingly, for the head10, conduction from the nozzle surface15to the holding member30is established via the cover head16A and the grounding plate80.

Although the surface of the cover head16A is treated for water repellency in order to suppress the attachment of liquids such as ink, water repellency treatment is not performed on the bent portion16cthat the plate spring portion82of the grounding plate80contacts. In so doing, it is possible to establish favorable conduction through the grounding plate80along with suppressing the attachment of liquids such as ink to the cover head16A.

As described above, according to the head unit1A according to the embodiment, an elastic sealing member76is provided between the head opening77of the cover70and the cover head16A of the head10. In so doing, it is possible to suppress the infiltration of ink, mist or the like to the head10from the exterior of the cover70via the gap between the head opening77and the cover head16A. Electrically, the head10conducts with the holding member30via the grounding plate80, and the cover70conducts with the holding member30. That is, even if the head10and the cover70do not directly conduct with one another, the head10and the cover70conduct with a common holding member30. In so doing, it is possible to suppress charging in the head10and the cover70by grounding the holding member30.

Although the conducting portion referred to in the aspect is a portion that electrically conducts with the cover head16A (protective plate) of the head10, in the present embodiment, the fixing portion74that contacts the holding member30of the cover70corresponds thereto. That is, the fixing portion74as the conducting portion indirectly electrically conducts with the cover head16A of the head10via the holding member30and the grounding plate80.

For the cover70according to the embodiment, the elastic sealing member76is interposed between the first groove forming member71and the outside member73, and is fixed in this state to the holding member30by a screw79. Therefore, even if the elastic sealing member76elastically deforms and a counterforce is applied in a direction in which the cover head16A separates from the grounding plate80, since the cover70is fixed to the holding member30by the screw79that is a fixing member, the sealing function due to the elastic sealing member76is maintained. Furthermore, the screw79serves a function of establishing conduction between the cover70and the holding member30along with fixing the cover70to the holding member30. Therefore, it is possible to achieve cost reductions by reducing the number of components.

In the embodiment, although the elastic sealing member76is provided between the cover head16A and the head opening77of the cover70, there is no limit thereto. For example, a conductive elastic sealing member may be used, or an adhesive may be used.

An ink jet recording apparatus that is an example of a liquid ejecting apparatus including the head unit1according to Embodiment 1 will be described.FIG. 27is a schematic perspective view of the ink jet recording apparatus according to the embodiment. Moreover, like elements to Embodiment 1 are given like references, and overlapping description will not be made.

The ink jet recording apparatus I is a so-called line-type recording apparatus in which the head unit1is fixed, and performs printing by transporting the ejection medium such as a recording sheet. More specifically, the ink jet recording apparatus I includes a head unit1, an apparatus main body2and a transport unit4that transports the ejection medium S.

The head unit1is attached to the apparatus main body2so that the ejection medium S is transported in a transport direction (X direction) orthogonal to the parallel direction (Y direction) of the nozzle row14. As described in Embodiment 1, the head unit1includes heads10arranged in a zig-zag pattern along the Y direction, and a nozzle row unit. In so doing, it is possible to perform printing in all regions across the Y direction that intersects the transport direction of the ejection medium S.

Although not shown in the drawings, a flow channel forming member is provided on the upper surface side of the head unit1. Ink is supplied from an ink storage unit, such as an ink tank or ink cartridge in which ink is stored, and the flow channel forming member supplies ink to each head10via the connection flow channel32of the holding member30. The ink storage unit may be provided integrated with the flow channel forming member, or may be held at a different position in the apparatus main body2from the head unit1.

The transport unit4includes, for example, a first transport unit7and a second transport unit8provided at both sides in the X direction of the head unit1.

The first transport unit7is configured with a driving roller7a, a driven roller7band a transport belt7cwound around the driving roller7aand the driven roller7b. The second transport unit8is configured with a driving roller8a, a driven roller8band a transport belt8csimilarly to the first transport unit7.

A driving unit, such as a driving motor not shown in the drawings, is connected to the respective driving rollers7aand8aof the first transport unit7and the second transport unit8, and the ejection medium S is transported to the upstream and downstream sides of the head unit1by the transport belts7cand8cbeing driven to rotate by the driving force of the driving unit.

According to such an ink jet recording apparatus I, printing is performed by ink being ejected from each head10of the head unit1and the ink landing on the ejection medium S while the ejection medium S is transported.

In the above-described example, although the head unit1is fixed to the apparatus main body2, and the transport unit4transports the ejection medium S, there is no limitation to such a form. Because the transport unit4causes the head unit1and the ejection medium S to relatively move, the ejection medium S may be fixed and the transport unit4may transport the head unit1. The ink jet recording apparatus I not only includes a case of including one head unit1, but may also include a plurality of head units1. Furthermore, it is also possible for the head unit1A according to Embodiment 2 to be mounted in the ink jet recording apparatus I similarly to the head unit1.

Other Embodiments

Above, the embodiments of the invention have been described, but the basic configuration of the invention is not limited to the above. The modification example below may be used alone or a plurality may be combined with the above-described embodiments or a combination thereof.

For example, although one conducting portion66provided in the cover60may be formed for each head10, there is no limitation to such a form. A configuration may be used in which conduction is established by a plurality of heads10contacting one conducting portion66.

The cover60is not necessarily attachable and detachable from the head unit1, and may be fixed with a screw or the like.

Furthermore, the invention may be widely applied to liquid ejecting apparatuses, and may also be applied to liquid ejecting apparatuses that include recording heads such as various ink jet recording heads that are used in an image recording apparatus, such as a printer, color material ejecting heads used to manufacture color filters for liquid crystal displays or the like, electrode material ejecting heads used to form electrodes, such as for organic EL displays and field emission displays (FED), and biological organic substance ejecting heads used to manufacture bio chips, and the like.