Liquid ejecting head unit and liquid ejecting apparatus

A liquid ejecting head unit includes a liquid ejecting head that ejects liquid through a nozzle formed in a nozzle surface, and a holding member to which the liquid ejecting head is attached. Further, in the liquid ejecting head unit, the holding member includes a holder that supports the liquid ejecting head in a predetermine direction which is different from a direction of the nozzle surface of the liquid ejecting head, and a base portion that sticks out from the holder to a side which is parallel to the predetermined direction.

CROSS REFERENCES TO RELATED APPLICATIONS

The entire disclosure of Japanese Patent Application Nos. 2012-105455, filed May 2, 2012, 2012-129944, filed Jun. 7, 2012, and 2012-227710, filed Oct. 15, 2012, are incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to liquid ejecting head units and liquid ejecting apparatuses, particularly to ink jet recording head units that discharge ink as liquid and ink jet recording apparatuses.

2. Related Art

A liquid ejecting apparatus is an apparatus that includes a liquid ejecting head capable of ejecting liquid as a droplet through nozzles and ejects various kinds of liquid from this liquid ejecting head. As an representative example of the liquid ejecting apparatus, for example, an image recording apparatus such as an ink jet recording apparatus (printer) or the like that includes an ink jet recording head (hereinafter, also called a “recording head”) and performs printing by ejecting a liquid ink as an ink droplet through a nozzle in the recording head, can be cited. In addition, the liquid ejecting apparatus is employed for ejecting various kinds of liquids such as coloring materials used in color filters of liquid crystal displays and the like, organic materials used in electro luminescence (EL) displays, electrode materials used in the formation of electrodes, and so on. A recording head of the image recording apparatus ejects a liquid ink, while a coloring material ejecting head of a display manufacturing apparatus ejects solutions of coloring materials of red (R), green (G) and blue (B). Further, an electrode ejecting head of an electrode material formation apparatus ejects a liquid electrode material, and a bioorganic matter ejecting head of a chip manufacturing apparatus ejects a solution of bioorganic matter.

Of the above-mentioned printers, such a printer is provided that is equipped with a recording head unit in which a plurality of recording heads are fixed to a support member (for example, see JP-A-2008-221745). Each of the recording heads is so configured as to introduce ink into a pressure chamber (pressure generation chamber) from an ink supply source such as an ink cartridge or the like, generate a change in pressure in the ink within the pressure chamber by activating a pressure generation unit such as a piezoelectric element, a heating element or the like, and eject the ink within the pressure chamber as an ink droplet through a nozzle that is opened in a nozzle surface by making use of the change in pressure. The support member is a plate-like member which is parallel to the nozzle surface of the recording head, and in which an opening portion is provided penetrating through in a plate-thickness direction thereof. Each of the recording heads is fixed to the border of the opening portion with a screw or the like while the nozzle surface thereof is exposed from the opening portion of the support member.

Recently, recording head units have been required to be smaller in size. However, in the above configuration, because the recording heads are fixed to the border of the opening portion of the support member, it has been difficult to miniaturize the recording head unit. In other words, in order to prevent deformation of the support member, an appropriate strength of the support member need be ensured; accordingly, the border of the opening portion is apt to be widened. In particular, the width of the support member in a direction perpendicular to an alignment direction of the recording heads cannot be shortened; as a result, it has been difficult to shorten the width of the recording head unit.

SUMMARY

An advantage of some aspects of the invention is to provide a liquid ejecting head unit that can be miniaturized and a liquid ejecting apparatus including this head unit.

A liquid ejecting head unit according to an aspect of the invention includes: a liquid ejecting head that has a nozzle surface in which a nozzle is formed, a pressure chamber communicating with the nozzle, and a pressure generation unit that generates a change in pressure within the pressure chamber, and that ejects liquid through the nozzle by driving the pressure generation unit to generate a change in pressure in the pressure chamber; and a support member to which the plurality of liquid ejecting heads are attached. Further, in the liquid ejecting head unit, the support member includes: a support wall having an attachment surface perpendicular to the nozzle surface of the liquid ejecting head that is to be attached to the stated attachment surface; and a flange sticking out from the attachment surface of the support wall in a direction intersecting with the attachment surface.

According to the aspect of the invention, since the flange that sticks out from the attachment surface of the support wall in the direction intersecting with the attachment surface, the strength of the support wall can be appropriately ensured, whereby the plate-thickness in a direction perpendicular to the attachment surface of the support wall can be thinner. This makes it possible to thin the width of the liquid ejecting head unit in the direction perpendicular to the attachment surface, whereby the liquid ejecting head unit can be miniaturized.

It is preferable for the flange to be provided at a position on the support wall at the side of a surface opposite to the nozzle surface of the liquid ejecting head.

According to this configuration, the flange can be provided in a state in which it does not interfere with the nozzle surface and overlaps with the nozzle surface when viewed from the nozzle surface side. Accordingly, a series of flanges across the plurality of liquid ejecting heads can be provided, whereby the strength of the support wall can be enhanced. This makes it possible to suppress deformation of the support wall and to make the plate-thickness in the direction perpendicular to the attachment surface of the support wall be thinner.

In the above configuration, it is preferable for the support member to be made of a metal.

According to this structure, it is possible to enhance rigidity of the support wall, whereby the plate-thickness in the direction perpendicular to the attachment surface of the support wall can be further thinned.

Further, it may be preferable that the liquid ejecting head unit include: a holding member having a base portion that is provided with a first liquid channel penetrating through in the thickness direction thereof in which liquid flows, and having a holder that is erected on the base portion; and the plurality of liquid ejecting heads each of which has a second liquid channel that is open at one side in which liquid flows, and discharges liquid supplied from the second liquid channel. Furthermore, it may be preferable that, in the liquid ejecting head unit, each of the plurality of liquid ejecting heads be fixed to the holder with the open side of the second liquid channel being opposed to the base portion, and the second liquid channel be connected with the first liquid channel.

According to this aspect, because it is unnecessary to ensure an area in which a connecting portion between the first and second liquid channels is located between the liquid ejecting heads, an interval between the liquid ejecting heads can be shortened as much as possible. Through this, a miniaturized liquid ejecting head unit can be provided. Note that the first liquid channel penetrates through in the thickness direction. That is, the first liquid channel is not excessively bent in the vicinity of the connecting portion with the second liquid channel, which can prevent pressure loss of the liquid.

Here, it is preferable that a tube member through which liquid flows be inserted into the first liquid channel, an insertion portion in which the second liquid channel is open and which sticks out toward the first liquid channel side be provided in an area of the liquid ejecting head on the side facing to the first liquid channel, and the second liquid channel communicate with the tube member by inserting the insertion portion into the inside of the tube member that is inserted into the first liquid channel. With this, the insertion portion side of the tube member is prevented from being excessively bent, whereby pressure loss of the liquid can be prevented.

Further, it is preferable that the leading portion of the tube member be bent outward centered at the insertion portion and be sandwiched between the liquid ejecting head and the base portion. With this, it is possible to prevent a leakage of liquid from the tube member.

Moreover, it may be preferable that the liquid ejecting head unit include the liquid ejecting head that ejects liquid through the nozzle formed in the nozzle surface and the holding member to which the liquid ejecting head is attached, and that the holding member include the holder that supports the liquid ejecting head in a predetermined direction which is different from a direction of the nozzle surface of the liquid ejecting head, and the base portion that sticks out from the holder to a side parallel to the predetermine direction.

The base portion may be provided sticking out from a position on the holder at an opposite side to the nozzle surface side of the liquid ejecting head.

The holding member may be made of a metal.

It is preferable for the base portion to include the first liquid channel which penetrates through in the thickness direction thereof and in which liquid is made to flow, for the liquid ejecting head to include the second liquid channel that supplies liquid to the nozzle, for the liquid ejecting head to be fixed to the holder with an opening of the second liquid channel facing to the base portion, and for the second liquid channel to be connected with the first liquid channel.

Further, it is preferable that the tube member for flowing liquid be inserted into the first liquid channel, and that the tube member be connected with the liquid ejecting head so as to flow the liquid.

It is preferable that the liquid ejecting head include the insertion portion in which the second liquid channel is open and which sticks out toward the first liquid channel side, and that the second liquid channel communicate with the tube member either by inserting the insertion portion into the inside of the tube member which is inserted into the first liquid channel or by inserting the tube member into the inside of the insertion portion.

It is preferable for the leading portion of the tube member to be bent outward centered at the insertion portion and be sandwiched between the liquid ejecting head and the base portion.

A liquid ejecting apparatus according to another aspect of the invention includes the liquid ejecting head unit according to the above-described aspects.

According to this aspect, it is possible to realize a liquid ejecting apparatus which can be miniaturized, and in which the pressure loss can be reduced by reducing flow resistance in a channel that supplies liquid to each of the liquid ejecting heads.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

First Embodiment

Hereinafter, the invention will be described in detail based on embodiments of the invention. An ink jet recording head unit is an example of a liquid ejecting head unit and is simply called a “head unit” as well. An ink jet recording head is an example of a liquid ejecting head and is simply called a “head” as well.

FIG. 1is a schematic perspective view illustrating the top face side of a head unit according to a first embodiment of the invention, andFIG. 2is a schematic perspective view illustrating the bottom face side of the head unit according to the embodiment. The top face side of the head unit is a face on the opposite side to a liquid ejecting surface of a head to be explained later, and the bottom face side of the head unit is a face on the liquid ejecting surface side.

A head unit1includes a plurality of heads10and a holding member30that holds the heads10.

The heads10form two head rows configured of head rows A and B in each of which four heads are aligned in a Y direction (first direction). The head rows A and B are arranged opposite to each other sandwiching the holding member30therebetween, and fixed to the holding member30in a state in which the relative positions between the heads10are specified.

The head10will be described in detail with reference toFIGS. 3 through 5.FIG. 3is a front view of the head10,FIG. 4is a top view of the head10, andFIG. 5is a bottom view of the head10.

The head10includes a main head body12provided with nozzle openings11, and a channel member13fixed to a surface on the opposite side of the main head body12to the nozzle openings11.

The main head body12includes a nozzle row14. A surface provided with the nozzle row14is referred to as a nozzle surface15(liquid ejecting surface).

The nozzle row14is a row in which a plurality of nozzle openings11are aligned in the Y direction (first direction). In this embodiment, two nozzle rows14aand14bare provided in which the nozzle openings11are aligned extending linearly in the Y direction. The nozzle openings11of the nozzle row14aas one row and the nozzle openings11of the nozzle row14bas the other row are formed while being shifted from each other by a half pitch. The nozzle rows14aand14bare configured to eject the same kind of liquid, and the two nozzle rows14aand14bform substantially the single nozzle row14. In the invention, the nozzle row14formed in a substantially single nozzle row is called a nozzle row. With this configuration, the resolution can be doubled. The nozzle row may be formed in a mode in which three or more rows configure substantially a single nozzle row. Needless to say, it may be that the head10is provided with a nozzle row formed by just one row. Moreover, it may be that the head10includes two or more nozzle rows and these nozzle rows eject different kinds of liquid from each other; in this case, a plurality of nozzle rows will be provided.

A cover head16to protect the nozzle surface15is provided on the main head body12. The cover head16is configured of an opening portion16afrom which the nozzle row14is exposed and a frame16bthat defines the opening portion16a. The frame16bcovers the circumferential portion of the nozzle surface15so as to protect the nozzle surface15.

Inside the main head body12, although not shown, there are provided a pressure generation chamber configuring a part of a channel that communicates with the nozzle openings11and a pressure generation unit that causes a change in pressure in the pressure generation chamber so as to discharge liquid through the nozzle openings.

The pressure generation unit is not limited to any specified one, and the following can be used, for example: that is, a unit that employs a piezoelectric element in which a piezoelectric material having an electromechanical conversion function is sandwiched between two electrodes; a unit such that a heating element is provided within the pressure generation chamber and droplets are discharged through the nozzle openings11by bubbles generated by the heat from the heating element; a unit such that static electricity is generated between a vibration plate and electrodes and droplets are discharged through the nozzle openings11by the deformation of the vibration plate due to electrostatic force; and so on. As a piezoelectric element, the following can be used: that is, a flexural vibration type piezoelectric element in which a lower-side electrode, a piezoelectric material, and an upper-side electrode are laminated in that order from the pressure generation chamber side so as to generate flexural vibration; a longitudinal vibration type piezoelectric element in which a piezoelectric material and an electrode formation material are alternately laminated so as to make the laminated materials expand and contract in the axis direction; and so on.

The channel member13is a member that is fixed to a surface on the opposite side to the nozzle openings11of the main head body12, and that includes an ink channel23(second liquid channel) which supplies ink from external to the main head body12and discharges ink from the main head body12to external. In a surface of the channel member13on the opposite side to the surface that is fixed to the main head body12, there is provided an insertion portion17in which the ink channel23inside the channel member13is open. At the upper surface side of the insertion portion17, the ink channel23is open. The insertion portion17is connected with a connection channel32(first liquid channel), details of which will be explained later.

Further, a connector18to which an electric signal such as a print signal or the like is supplied from external is provided on the surface on the opposite side of the channel member13to the surface which is fixed to the main head body12. A flexible connection wiring19such as an FPC or the like for transmitting the print signal is connected to the connector18.

A fixing portion20sticking out in the Y direction is provided in the channel member13. The fixing portion20is formed in a plate-like shape approximately parallel with a Y-Z plane, and is provided approximately at the center in the X direction of the channel member13. In the fixing portion20, a positioning hole21and a fixing screw insertion hole22are provided penetrating through in the thickness direction. The positioning hole21and the fixing screw insertion hole22are positioned in compliance with the positioning reference of the holding member30, details of which will be explained later. The positioning hole21and the fixing screw insertion hole22are fixed to the holding member30being positioned in compliance with the positioning reference, whereby the relative positions between the heads10are specified.

Details of the holding member will be described with reference toFIGS. 6 through 9hereinafter.FIG. 6is a front view of the holding member,FIG. 7is a top view of the holding member,FIG. 8is a bottom view of the holding member, andFIG. 9is a cross-sectional view taken along a IX-IX line inFIG. 8.

The holding member30is a member that is formed to be elongated in the Y direction and that holds a head row10A and a head row10B. More specifically, the holding member30includes a base portion31and a holder40to which the head10is attached. Further, as shown inFIG. 9, the cross-section of the holding member30is formed approximately in a T shape. In the approximate T shape, the crossbar portion corresponds to the base portion31and the vertical bar portion corresponds to the holder40. However, the invention is not limited to the approximate T shape. For example, there may be provided a portion that sticks out upward from the crossbar portion of the approximate T shape like a cross-shape or a portion that sticks out downward therefrom.

The base portion31is a portion that is formed in a plate-like shape having a surface approximately parallel to the nozzle surface15(seeFIG. 5), and that is located on the top face side of the heads10. The connection channel32(first liquid channel) is provided in the base portion31penetrating through in the thickness direction. The connection channel32is connected with the ink channel23(seeFIGS. 3 and 4) that is open in the insertion portion17of the head10. An ink tube25which is an example of the tube member is inserted into the connection channel32from a liquid storage unit such as an ink cartridge or the like, and ink is supplied to the ink channel23via the tube, details of which will be explained later. In this embodiment, two connection channels32are provided for each of the heads10in the base portion31.

A connection wiring recess33is provided on a side surface of the base portion31(surface parallel to the Y-Z plane). The connection wiring19connected with the head10(seeFIGS. 3 and 4) is accommodated in the connection wiring recess33.

The holder40is erected on the base31to hold the head10. The holder40is also called a support wall because it is a wall-like member for supporting the head10. In this embodiment, the holder40is formed in a plate-like shape longer in the Y direction and shorter in the X direction. On both sides of the holder40, there are provided a head attachment surface41and an accommodation portion42which is a concave portion recessed from the head attachment surface41. The fixing portion20of the head10is attached to the head attachment surface41, while the accommodation portion42is a space in which the main head body12and the channel member13of the head10are accommodated. Here, because it can be considered that the base portion31sticks out laterally from the holder40to reinforce the holder40, the base portion31is also referred to as a flange.

To be more specific, the holder40has a configuration in which a thick portion43having the head attachment surface41and a thin portion44formed thinner than the thick portion43are included, and the thin portion44is located between the adjacent thick portions43in the Y direction to form the accommodation portion42.

Here, the depth in the X direction from a side surface of the base portion31to the bottom surface of the accommodation portion42(front face of the thin portion44) is taken as D1, and the depth in the X direction from the head attachment surface41to the bottom surface of the accommodation portion42is taken as D2. The depth D1is formed slightly deeper than the width in the X direction of the head10. The depth D2is formed slightly deeper than a width W from the fixing portion20to a side surface in the X direction of the head10(seeFIG. 4).

Accordingly, the head10fixed to the head attachment surface41is accommodated in the accommodation portion42without making contact with the bottom surface of the accommodation portion42and also without sticking out from the side surface of the base portion31.

A positioning reference hole45and a fixing screw hole46each penetrating through in the width direction (X direction) of the thick portion43are provided in the head attachment surface41. The positioning reference hole45specifies the relative positions between the heads10, details of which will be explained later. The fixing screw hole46is a screw hole in which a fixing screw inserted through the fixing screw insertion hole22of the head10(seeFIG. 3) is screwed, details of which will be explained later. The head10is fixed to the head attachment surface41with the fixing screw.

The accommodation portion42located on one of both the sides of the holder40is so provided as to be opposed to the head attachment surface41(thick portion43) which is located on the other side. Meanwhile, one head attachment surface41is provided between the two accommodation portions42adjacent to each other in the Y-direction. Each of the fixing portions20of the two heads10that are respectively accommodated in those accommodation portions42adjacent to each other, is fixed to the one head attachment surface41.

In this embodiment, the four accommodation portions42corresponding to the head row10A and the four accommodation portions42corresponding to the head row10B are respectively provided on both the sides of the holder40, and the head attachment surfaces41are provided at both end sides in the Y direction of each of the accommodation portions42. By attaching each of the heads10to the holder40having the above-described head attachment surface41and accommodation portion42, the head row10A and the head row10B are opposed to each other sandwiching the holders40therebetween so as to be arranged in a zigzag pattern along the Y direction, details of which will be explained later.

Further, a tapered surface47is formed at a boundary between the head attachment surface41and the accommodation portion42. The tapered surface47functions as a lead-in structure for guiding the head10into the accommodation portion42(holder40side), details of which will be explained later.

Note that in the holding member30, the base portion31and the holder40are integrally formed as one unit. This enhances the rigidity of the base portion31and the holder40. Needless to say, the base portion31and the holder40may be formed as different members from each other, and the holding member30may be formed by bonding those different members. Further, although the material of the holding member30is not limited to any specific material, it is preferable to use a material having a sufficient rigidity such as SUS or the like.

Hereinafter, a structure in which the heads10are attached to the holding member30will be described in detail with reference toFIGS. 10 through 12.FIG. 10is a bottom view of the head unit,FIG. 11is a front view of the head unit, andFIG. 12is a cross-sectional view taken along a XII-XII line inFIGS. 10 and 11.

The heads10that configure the head row10A and the head row10B are respectively fixed to both the sides of the holders40of the holding member30. To be more specific, the heads10are fixed in the following manner.

The main head body12and the channel member13of each of the heads10are accommodated in the corresponding accommodation portion42, and the fixing portion20thereof is in contact with head attachment surface41. A positioning pin50is inserted through both the positioning hole21provided in the fixing portion20of the head10and the positioning reference hole45provided in the head attachment surface41. The openings of the positioning hole21and the positioning reference hole45are both formed in a shape so as to make the opening to be in contact with the outer circumference of the positioning pin50.

Further, a fixing screw51is inserted through the fixing screw insertion hole22provided in the fixing portion20and screwed into the fixing screw hole46provided in the head attachment surface41. Note that the fixing screw51is not screwed into the fixing screw insertion hole22, and the head of the fixing screw51fixes the fixing portion20to the head attachment surface41.

The connection wiring19connected with the head10is accommodated in the connection wiring recess33provided on the base portion31, and an end portion thereof is connected to a control device (not shown) that supplies a drive signal. Providing the connection wiring recess33on the base portion31makes it possible to accommodate the connection wiring19while preventing the connection wiring19from sticking out from a side surface of the base portion31.

The head attachment surface41to which the head10is fixed in the manner described above and the positioning reference hole45, function as a positioning reference that specifies the relative positions between the heads10.

The head attachment surface41specifies the positions in the X direction of the heads10. In other words, the position of the head10is determined by the fixing portion20of the head10making contact with the head attachment surface41.

The positioning reference hole45specifies the positions in the Y and Z directions of the heads10. In other words, the positioning hole21of the head10is positioned to the same position as that of the positioning reference hole45in the Y-Z plane and the positioning pin50is inserted through these holes, whereby the position of the head10in the Y and Z directions is determined. That is, by inserting the positioning pin50through the positioning reference hole45and the positioning hole21, movement of the head10in the Y and Z directions is restricted.

In a state in which the position in the X, Y and Z directions is specified by the head attachment surface41and the positioning reference hole45, as described above, the head10is fixed to the head attachment surface41with the fixing screw51.

The head attachment surface41and the positioning reference hole45, which function as the positioning reference in the manner described above, are formed in the holder40so as to specify the relative positions between the heads10being positioned by the head attachment surface41and positioning reference hole45.

Here, the “relative positions between the heads10” refers to an arrangement of the heads10such that the heads10are arranged in a zigzag pattern in the Y direction and the nozzle rows14of the heads10form a single continuous nozzle row unit.

The “heads10are arranged in a zigzag-pattern” refers to an arrangement as follows. That is, the nozzle openings11(one or more in number) located at the end side in the Y direction of the head10of the head row10A (head row10B) are arranged so that the position thereof overlaps with the position in the Y direction of the nozzle openings11of the head10of the head row10B (head row10A).

In the manner as describe above, the nozzle rows14are arranged to overlap partly with each other in the Y direction between the heads10so as to continue the nozzle rows14, whereby the nozzle row unit forming the maximum print width as a whole is configured. In other words, the nozzle row unit is a unit in which the nozzle rows of all of the heads10in the head unit1are continued.

In this embodiment, the positioning reference is formed as follows in order to form the above nozzle row unit. That is, the head attachment surfaces41each serving as the positioning reference in the X direction are flush with each other with respect to every both sides of the holders40. In other words, the nozzle rows14aand14bof the head row10A and of the head row10B being attached to the corresponding head attachment surfaces41, are each linearly aligned on a line parallel to the Y direction.

The positioning reference hole45serving as the positioning reference in the Y and Z directions is formed so that the end portion of the nozzle openings11is overlapped in the Y direction in the manner described above, and the nozzle surfaces15are flush with each other in the Z direction.

By positioning the head10to the head attachment surface41and the positioning reference hole45serving as the positioning reference and fixing the head10with the fixing screw51, there is provided the head unit1in which the nozzle surfaces15are flush with each other, the head rows10A and10B are opposed to each other sandwiching the holders40therebetween, and therefore the nozzle row unit is formed. Note that a channel member60is provided on the upper surface of the holding member30of the head unit1. The channel member60is a member that holds therein the ink tube25in which ink supplied from an ink cartridge flows.

Hereinafter, a structure that supplies ink to the head10will described in detail with reference toFIG. 13.FIG. 13is an enlarged cross-sectional view illustrating a principal portion of a connecting portion between the head10and the holding member30.

The ink tube25, which is an example of the tube member in which liquid flows, is inserted into the connection channel32of the holding member30. The ink tube25is formed of a flexible material, and one end thereof is connected with the insertion portion17and the other end is connected with an ink cartridge (not shown). The outer diameter of the ink tube25is formed to be approximately the same as the inner diameter of the connection channel32. In this embodiment, a plurality of ink tubes25corresponding to the ink channels23of the heads10are held in the channel member60, and each leading portion of the ink tubes25is inserted into the connection channel32. Note that in this embodiment, as described above, liquid flows inside of the ink tube25being positioned inside of the connection channel32; even in such case, it will be described in this embodiment that “liquid flows inside the connection channel32”.

Meanwhile, in an area of the head10facing to the connection channel32, there is provided the insertion portion17that sticks out toward the connection channel32side. The outer diameter of the insertion portion17is formed to be approximately the same as the inner diameter of the ink tube25, and the ink channel23is open at the upper surface (surface on the connection channel32side) of the insertion portion17. The insertion portion17is inserted into the inside of the ink tube25that is inserted into the connection channel32, which makes the ink channel23communicate with the ink tube25.

Further, a leading portion25aof the ink tube25(end portion of the ink tube25on the insertion portion17side) sticks out toward the head10side from the connection channel32and is bent outward centered at the insertion portion17. The leading portion25abent in this manner is sandwiched between the head10and the base portion31.

In the above-described head unit1, ink is supplied to the connection channel32from an ink cartridge (not shown) via the ink tube25, and is further supplied to the main head body12via the ink channel23(seeFIG. 3). Then, ink droplets are discharged through the nozzle openings11of each of the heads10based on the drive signal from the control device.

In the head unit1having been described thus far, each of the heads10is attached to the holder40of the holding member30, and the insertion portion17in which the ink channel23is open faces the base portion31; further, the ink channel23communicates with the ink tube25that is inserted into the connection channel32. In other words, the ink channel23of the head10is open at the upper surface of the head10(surface on the opposite side to the nozzle surface15) to be connected with the ink tube25.

As shown in a top view of the head unit inFIG. 14, by providing the insertion portion17in which the ink channel23is open at the upper surface side of the head10, it is possible to arrange a connecting portion between the ink tube25and the head10(the insertion portion17, the leading portion of the ink tube25to be inserted into the insertion portion17, and the like) not at a position between the heads10in the X-Y plane, but at a position that overlaps with the head10.

With this, because it is unnecessary to ensure an area between the heads10in which the connecting portion between the ink tube25and the head10is positioned, the interval between the heads10can be shortened as much as possible, which provides the miniaturized head unit1.

Further, as shown inFIG. 13, the insertion portion17is inserted into the ink tube25, and the ink tube25is inserted into the connection channel32. By inserting the ink tube25into the connection channel32in this manner, the ink tube25is held in a state in which it linearly extends along the connection channel32. This prevents the ink tube25from being excessively bent from the leading portion connected with the insertion portion17.

As described above, since the ink tube25is prevented from being excessively bent, it is possible to prevent the pressure loss of ink within the ink tube25and to provide the head unit1having a preferable ink discharge characteristic.

Moreover, the leading portion25aof the ink tube25is sandwiched between the base portion31and the head10. This causes the ink tube25to adhere tightly to the upper surface of the head10(upper surface of the circumferential border of the insertion portion17), thereby making it possible to prevent the leak of ink from the ink tube25.

In the head unit1according to this embodiment, the fixing portion20of the head10is not attached to a surface parallel to the nozzle surface15, but attached to the head attachment surface41intersecting with the nozzle surface15.

Here, assume that the interval between the heads10is shortened so as to cause the nozzle openings11of the heads10configuring the head row10A and head row10B to overlap with each other in the Y direction. This requires the fixing portion20located between the heads10to be shorter in width in the Y direction. However, by widening the width in the Z direction of the fixing portion20, the fixing portion20can have a sufficiently large size for stably fixing the head10to the head attachment surface41.

As described above, the nozzle row unit is formed by making the interval between the heads10shorter, and the head unit1is provided in which the heads10are stably fixed to the holding member30. In addition, because the heads10are stably fixed to the holding member30while the relative positions of the heads10are precisely arranged so as to form the nozzle row unit, the head unit1has a preferable ink discharge characteristic.

If it is attempted to fix the heads10to a member equivalent to the holding member on a surface parallel to the nozzle surface15, a part for fixing the head10to the above-mentioned member need be formed more finely as the interval between the heads10is shorter. Because of this, the head10cannot be stably fixed to the above-mentioned member.

Moreover, in the head unit1, it is possible to position the head10in the X, Y and Z directions with the head attachment surface41and positioning reference hole45provided in the holder40. In other words, the head unit1can be obtained in which the relative positions between the heads10are specified only by causing the fixing portion20of the head10to make contact with the head attachment surface41and inserting the positioning pin50into the positioning reference hole45and the positioning hole21.

In the past technique, in order to specify the relative positions between the heads10, for example, the positioning is performed so that the nozzle openings11of the respective heads10are positioned to be a predetermined arrangement. Specifically, the nozzle openings11are pictured with a CCD camera or the like, the positions of the heads10are finely adjusted so that the nozzle openings11in the picture are arranged at a predetermined interval, and then the heads10are fixed to a member equivalent to the holding member.

However, with the head unit1according to this embodiment, unlike in the past technique, the relative positions between the heads10can be specified without carrying out fine adjustment on the positions of the heads10. This is particularly advantageous in maintenance operation at the site where the head unit1is being used, because it is possible to noticeably reduce a workload, time, or the like needed for exchanging a specified head10.

Providing the tapered surface47as a lead-in structure to the holder40makes it easy to attach the head10to the holder40. This will be explained with reference toFIG. 15.FIG. 15is an enlarged bottom view illustrating a principal portion of the head unit for explaining the lead-in structure.

As shown inFIG. 15, assume that the head10is to be accommodated in the accommodation portion42while being slightly deviated in the Y direction with respect to the accommodation portion42. At this time, part of the head10makes contact with the tapered surface47. Then, the head10is guided to the accommodation portion42side along the tapered surface47.

Providing the lead-in structure to the accommodation portion42in the above manner makes it easy to accommodate the head10in the accommodation portion42. With this, it is possible to reduce a workload, time, or the like needed for exchanging the heads10and to reduce maintenance costs in the exchanging of the heads.

Further, in the head unit1according to this embodiment, the accommodation portion42is provided in the holder40, and the head10is accommodated in the accommodation portion42and fixed. This makes it possible to shorten the interval in the X direction between the heads10that are oppositely arranged sandwiching the holders40therebetween. In other words, the interval between the nozzle rows14of the heads10can be shortened. By shortening the interval in the X direction between the nozzle rows14in the above manner, it is possible to suppress influence of meandering transport of a medium such as paper onto which ink is discharged, whereby deterioration in the print quality can be prevented.

Second Embodiment

In the first embodiment, the ink channel23is open in the insertion portion17and is connected with the ink tube25being inserted into the connection channel32; however, the invention is not limited thereto.

FIG. 16is an enlarged cross-sectional view illustrating a principal portion of a connecting portion between the head10and the holding member30according to a second embodiment of the invention. Note that the same elements as those in the first embodiment will be given the same reference numerals and duplicate description thereof Will be omitted.

The insertion portion17according to this embodiment is directly connected with the connection channel32. That is, unlike in the first embodiment, the insertion portion17is connected with the connection channel32without using the ink tube25. The connection channel32communicates with a channel61of the channel member60that is provided to the holding member30, for example. The channel61of the channel member60supplies ink to the connection channel32, and this supplied ink is then supplied to the ink channel23.

In the head unit1of the above configuration in which the ink tube25is not used, because the connection channel32extends linearly penetrating through in the thickness direction, it is possible to prevent the pressure loss due to an excessively bent ink channel. In addition, the head unit1in this configuration can be also miniaturized like in the first embodiment.

Third Embodiment

An ink jet recording apparatus as an example of a liquid ejecting apparatus including the head unit1according to the first embodiment will be described.FIG. 17is a schematic perspective view of an ink jet recording apparatus according to a third embodiment of the invention. Note that the same elements as those in the first embodiment are given the same reference numerals and duplicate description thereof will be omitted.

An ink jet recording apparatus I is what is known as a line type recoding apparatus in which the head unit1is fixedly installed and printing is performed by transporting an ejection-target medium such as a recording sheet. To be more specific, the ink jet recording apparatus I includes the head unit1, a main apparatus body2, and a transport unit4that transports an ejection-target medium S.

The head unit1is installed in the main apparatus body2so that the ejection-target medium S is transported in a transport direction (X direction) orthogonal to the alignment direction (Y direction) of the nozzle row14(seeFIG. 5). As described in the first embodiment, in the head unit1, the heads10are arranged in a zigzag pattern along the Y direction, and the nozzle row unit is included in the head unit1. This makes it possible to perform printing across the entire area in the Y direction intersecting with the transport direction of the ejection-target medium S.

The channel member60is provided on the upper surface side of the head unit1. The channel member60is a member that is supplied with ink via the ink tube25from an ink storage unit (not shown) in which ink is stored such as an ink tank, an ink cartridge, or the like, and that supplies the ink to each of the heads10via the connection channel32of the holding member30. The ink tube25is held in the channel member60with its leading portion being inserted into the connection channel32of the holding member30, as described in the first embodiment, and the insertion portion17of the head10(ink channel23) is inserted into the ink tube25.

A transport unit4includes a first transport unit7and a second transport unit8that are respectively provided on both sides in the X direction of the head unit1.

The first transport unit7is configured of a drive roller7a, a driven roller7b, and a transport belt7cwound upon the drive roller7aand the driven roller7b. The second transport unit8includes, like the first transport unit7, a drive roller8a, a driven roller8b, and a transport belt8c.

The drive roller7aof the first transport unit7and the drive roller8aof the second transport unit8are each connected with a driving unit (not shown) such as a driving motor, and the ejection-target medium S is transported on the upstream side and the downstream side of the head unit1by rotation of the transport belts7cand8ceach driven by a driving force of the driving unit.

In this embodiment, the first transport unit7configured of the drive roller7a, the driven roller7band the transport belt7c, and the second transport unit8configured of the drive roller8a, the driven roller8band the transport belt8care exemplified; however, a holding unit that causes the ejection-target medium S to be held on the transport belts7cand8cmay be additionally provided. For example, the holding unit may have a charging unit that charges the outer periphery of the ejection-target medium S, and may cause the charged ejection-target medium S to stick to the upper side of the transport belts7c,8cby the effect of dielectric polarization. Further, a press-down roller may be provided as a holding unit on each of the transport belts7cand8c, and the ejection-target medium S may be pinched between the press-down rollers and the transport belts7c,8c.

According to the above-mentioned ink jet recording apparatus I, preferable printing can be performed on the ejection-target medium S because the heads10are stably fixed to the holding member30.

In the example described above, although the head unit1is fixed to the main apparatus body2and the transport unit4is configured to transport the ejection-target medium S, the invention is not limited to such mode. Since it is sufficient that the transport unit4relatively moves the head unit1and the ejection-target medium S, the transport unit4may transport the head unit1while the ejection-target medium S being fixed. Moreover, the ink jet recording apparatus I may include not only the single head unit1, but also a plurality of head units1.

Other Embodiments

Thus far, the embodiments of the invention have been described. However, the basic configuration of the invention is not limited thereto. For example, the above-described embodiments may be combined with each other, or may be combined with the following modes.

Although, in the first embodiment, the leading portion of the ink tube25is bent to the outer side of the insertion portion17and sandwiched between the base portion31and the head10, the invention is not limited thereto. For example, the ink tube25may be inserted into the connection channel32without the tube being bent, and in this state, the insertion portion17may be inserted into the ink tube25. On the other hand, the ink tube25may be inserted into the connection channel32without being bent, and the ink tube25may be inserted into the insertion portion17.

Further, although the ink channel23is open in the insertion portion17of the head10, the invention is not limited thereto. For example, an opening into which the ink tube25can be fitted may be provided in a surface of the head10that is opposed to the base portion31, and the ink channel23within the head10may communicate with the ink tube25when the ink tube25is fitted into the opening.

Furthermore, although the head unit1includes the two rows of the head row10A and head row10B that are arranged in a zigzag pattern, the invention is not limited thereto. For example, the heads10may be fixed to the holders40in a manner such that a head row is formed at only one side of the holders40. Even in this case, it is possible to miniaturize the head unit1by shortening the interval between the heads in the Y direction of the above head row, and to prevent the ink tube25from being excessively bent.

Although the positioning reference hole45as a positioning reference specifies a position in the Y and Z directions of the head10, the invention is not limited thereto. That is, for example, the positioning reference hole45is considered to be a hole that specifies a position in the Y direction. In this case, the positioning reference hole45has such a diameter in the Y direction that makes contact with the outer circumference of the positioning pin50, and has such a diameter in the Z direction that is larger than the positioning pin50. In other words, the positioning reference hole45is made to be an elongate hole, which is lengthened in the Z direction.

With this, in the case where the positioning pin50is inserted through the positioning reference hole45and the positioning hole21, the head10is restricted to move in the Y direction but allowed to move in the Z direction to a small extent.

Then, the base portion31is provided with a positioning reference (base portion-side reference) in the Z direction. Although the form or the like of the base portion-side reference is not limited to any specified form or the like, a part in contact with the upper surface of the head10can be made to be the base portion-side reference, for example. The base portion-side reference is provided to the base portion31so as to specify the relative positions in the Z direction between the heads10that are fixed to the holder40being positioned in compliance with the base portion-side reference.

As described above, in the case where the positioning reference in the Z direction can be provided to the base portion31, the position in the Z direction of the head10can be specified through positioning the head10in compliance with the positioning reference provided to the base portion31.

The positioning references can be realized in various modes without being limited to the head attachment surface41, the positioning reference hole45, or the like. For example, a projection provided on a side surface of the holder40can be made to be a positioning reference in place of the positioning reference hole45. By inserting the projection into the positioning hole21, the position of the head10can be specified.

The invention can be widely applied to liquid ejecting heads in general. That is, the invention can be applied to, for example, recording heads such as various kinds of ink jet recording heads that are used in image recording apparatuses such as a printer or the like, coloring material ejecting heads used in the manufacture of color filters for liquid crystal displays and the like, electrode material ejecting heads used in the formation of electrodes for organic EL displays, field ejection displays (FEDs) and the like, bioorganic matter ejecting heads used in the manufacture of biochips, and so on. It is needless to say that liquid ejecting apparatuses equipped with these liquid ejecting heads are not limited to any specified apparatuses.