A first flow path through which liquid flows in an intersection direction intersecting a vertical direction and a second flow path which is connected to the first flow path and through which liquid flows downward in the vertical direction are provided. The first flow path includes an intersection portion which has a surface intersecting the intersection direction and which allows a cross-sectional area of the first flow path to be gradually reduced in a plane perpendicular to the intersection direction as the first flow path extends to the second flow path.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2014-056180 filed on Mar. 19, 2014. The entire disclosure of Japanese Patent Application No. 2014-056180 is hereby incorporated herein by reference.

BACKGROUND

1. Technical Field

The present invention relates to a flow-path forming member in which liquid is ejected from nozzle openings, a liquid ejecting head, and a liquid ejecting apparatus.

2. Related Art

An ink jet type recording head which includes a head main body in which a pressure generation chamber communicating with a nozzle opening through which ink droplets are discharged is deformed by a pressure generation unit, such as a piezoelectric element, in such a manner that ink droplet is discharged through the nozzle opening and a flow-path member which constitutes a flow path of ink supplied to the head main body is known as a liquid ejecting head.

In such an ink jet type recording head, it is necessary to reduce pressure loss in a flow path when a plurality of heads has a common ink supply source or the distance from the ink supply source to the head is long.

Furthermore, although air bubbles are likely to remain on an upper side of a flow path in a vertical direction, it is necessary to allow the air bubbles to flow downstream while preventing the air bubbles from remaining in the flow path. It is preferable that flow velocity is great, in terms of allowing the air bubbles to flow downstream. However, when the flow velocity is great, the pressure loss increases, and thus it is unpreferable.

Here, technique in which, in a connection portion between a flat flow path and a vertical flow path, a flow path on an upper side in a vertical direction have a cycloid curve shape, in such a manner that air bubbles are prevented from remaining on the upper side of the connection portion in the vertical direction has been disclosed (see JPA-2012-210771).

However, only a problem in relation to discharge of air bubbles is considered and a problem in relation to pressure loss is not considered in JP-A-2012-210771 described above. Accordingly, it is necessary to provide a flow path structure in which both improvement in air-bubble discharge properties and a reduction in pressure loss can be achieved.

Such a problem is not limited to an ink jet type recording head but is shared by a liquid ejecting head unit which ejects liquid other than ink.

SUMMARY

An advantage of some aspects of the invention is to provide a flow-path forming member in which both improvement in air-bubble discharge properties and a reduction in pressure can be achieved, a liquid ejecting head, and a liquid ejecting apparatus.

According to an aspect of the invention, there is provided a flow-path forming member which includes a first flow path through which liquid flows in an intersection direction intersecting a vertical direction and a second flow path which is connected to the first flow path and through which liquid flows downward in the vertical direction. The first flow path includes an intersection portion which has a surface intersecting the intersection direction and which allows a cross-sectional area of the first flow path to be gradually reduced in a plane perpendicular to the intersection direction as the first flow path extends to the second flow path.

In this aspect, the first flow path includes the intersection portion, and thus the cross-sectional area of the flow path of the intersection portion is gradually reduced. As a result, it is possible to reduce the pressure loss in a part of the first flow path, which is the portion to the intersection portion. In addition, the flow velocity in the intersection portion increases, and thus air bubbles are prevented from remaining on the upper side of the connection portion between the first flow path and the second flow path.

In the flow-path forming member according to Aspect 1, it is preferable that the intersection portion of the first flow path has the intersection surface on a lower side in the vertical direction. In this aspect, the flow of liquid is directed to the upper side of the intersection portion in the vertical direction. As a result, it is possible to more reliably prevent air bubbles from remaining on the upper side of the connection portion in the vertical direction.

In the flow-path forming member according to Aspects 1 and 2, it is preferable that a plurality of groups of the first flow paths and the second flow paths are provided. In addition, it is preferable that the respective first flow paths of the plurality of groups communicate with a distribution flow path. Furthermore, it is preferable that the distribution flow path communicates with an inlet port to which a liquid from a liquid supply source is supplied from the vertical direction. It is preferable that the respective intersection portions of the first flow paths of the groups have different shapes in accordance with distances from the inlet port to the respective second flow paths. In this aspect, the intersection portion is designed in consideration of the amount of the pressure loss in each flow path which extends from the inlet port to the intersection portion. As a result, the pressure loss in the intersection portion is adjusted, and thus variation in pressure losses in the groups can be reduced.

In the flow-path forming member according to Aspect 3, it is preferable that the groups of the first flow paths and the second flow paths include a first group and a second group in which the distance from the inlet port to the second flow path is longer than that of the first group. In addition, it is preferable that the distance from a start position of the intersection portion of the first group to the second flow path thereof is longer than that of the second group. In this aspect, the distances from the second flow paths to the start points of the intersection portions are adjusted, in such a manner that variation in the pressure losses in the groups can be reduced, in which the pressure loss increases as the distance from the inlet port increases.

In the flow-path forming member according to Aspects 3 and 4, it is preferable that the groups of the first flow paths and the second flow paths include a first group and a second group in which the distance from the inlet port to the second flow path is longer than that of the first group. Furthermore, it is preferable that the distance from an end position of the intersection portion of the first group to the second flow path is longer than that of the second group. In this aspect, the distances from the second flow paths to the end points of the intersection portions are adjusted, in such a manner that variation in the pressure losses in the groups can be reduced, in which the pressure loss increases as the distance from the inlet port increases.

In the flow-path forming member according to Aspects 3 to 5, it is preferable that the cross-sectional area of a part of the distribution flow path, which is the portion from the inlet port to a first bifurcation flow path which branches off first is greater than the cross-sectional area of a part of the distribution flow path, which is the portion downstream from the first bifurcation flow path which branches off first. In this aspect, even when the flow rate in the distribution flow path changes in accordance with the number of the first flow paths connected to the distribution flow path, the cross-sectional area of the distribution flow path changes in accordance with the number of bifurcation portions, in such a manner that variation in the flow velocity in the distribution flow path can be reduced.

In the flow-path forming member according to Aspects 1 to 6, it is preferable that the flow-path forming member further includes a first member and a second member. In addition, it is preferable that the first flow path is formed by the first member and the second member. Furthermore, it is preferable that the intersection portion is formed not in the first member but in the second member. In this aspect, it is easy to perform processing, compared to in the case where the intersection portion is formed over the first member and the second member.

In the flow-path forming member according to Aspect 7, it is preferable that a part of the intersection portion, which decides the cross-sectional area, is located further on the second member side than an overlapping surface between the first member and the second member. When a part of the intersection portion, which decides the second cross-sectional area, is located in the overlapping surface between the first member and the second member or on the first member side, it is difficult to manage an adhesion surface. However, in this aspect, the intersection portion is provided on the second member side, and thus it is relatively easy to manage the adhesion surface.

In the flow-path forming member according to Aspects 7 and 8, it is preferable that the flow-path forming member further includes a third member. In addition, it is preferable that, when a plurality of groups of the first flow paths and the second flow paths are provided, there is a first flow path formed by the second member and the third member, in addition to a first flow path formed by the first member and the second member. In this aspect, the first flow paths are formed in both sides of the second member. As a result, it is possible to reduce the number of parts.

In the flow-path forming member according to Aspect 9, it is preferable that the intersection portion of the first flow path formed by the second member and the third member is formed not in the second member but in the third member. In this aspect, it is easy to perform processing, compared to in the case where the intersection portion is formed by the second member and the third member.

In the flow-path forming member according to Aspects 9 and 10, it is preferable that, when a first flow path of a first stage, which is formed by the first member and the second member, and a first flow path of a second stage, which is formed by the second member and the third member, are projected onto a plane including the intersection direction and the vertical direction, the projection images thereof do not overlap each other. In this aspect, the first flow path of the first stage and the first flow path of the second stage can be arranged close to each other in a direction intersecting the vertical direction. As a result, it is possible to reduce the size of the flow-path forming member in the direction intersecting the vertical direction.

In the flow-path forming member according to Aspects 9 and 10, it is preferable that, when a first flow path of a first stage, which is formed by the first member and the second member, and a first flow path of a second stage, which is formed by the second member and the third member, are projected onto a plane including the intersection direction and the vertical direction, the projection images thereof overlap each other. In this aspect, the first flow path of the first stage and the first flow path of the second stage overlap in the vertical direction. As a result, it is possible to reduce the size of the flow-path forming member in the direction intersecting the vertical direction.

In the flow-path forming member according to Aspects 9 to 12, it is preferable that a plurality of groups of the first flow paths and the second flow paths of the first stage and a plurality of groups of the first flow paths and the second flow paths of the second stage are provided. In addition, it is preferable that the respective first flow paths of the first stage communicate with a first distribution flow path and the respective first flow paths of the second stage communicate with a second distribution flow path. Furthermore, it is preferable that the respective first distribution flow paths and the respective second distribution flow paths communicate with inlet ports to which liquid from a liquid supply source is supplied from the vertical direction. It is preferable that the cross-sectional area of the first distribution flow path is smaller than that of the second distribution flow path. In this aspect, variation in the pressure loss in the flow path extending to the first flow path of the first stage and variation in the pressure loss in the flow path extending to the first flow path of the second stage can be adjusted by the cross-sectional areas of the distribution flow paths of the respective stages.

In the flow-path forming member according to Aspects 1 to 13, it is preferable that the cross-sectional area of the second flow path is smaller than that of the first flow path communicating with the second flow path. In this aspect, the flow velocity in the second flow path increases, in such a manner that it is possible to cause air bubbles to effectively flow.

According to another aspect of the invention, there is provided a liquid ejecting head which includes the flow-path forming member according to any one of Aspects 1 to 14 and a head main body which receives liquid from the flow-path forming member and ejects the liquid.

In this aspect, the first flow path includes the intersection portion, and thus the cross-sectional area of the flow path of the intersection portion is gradually reduced. As a result, it is possible to reduce the pressure loss in a part of the first flow path, which is the portion to the intersection portion. In addition, the flow-path member in which the flow velocity in the intersection portion increases, and thus air bubbles can be prevented from remaining on the upper side of the connection portion between the first flow path and the second flow path is provided. As a result, it is possible to provide a liquid ejecting head having a flow-path member in which pressure loss is reduced and excellent air-bubble discharge properties are ensured.

According to still another aspect of the invention, there is provided a liquid ejecting apparatus which includes the liquid ejecting head according to Aspect 15.

In this aspect, the first flow path includes the intersection portion, and thus the cross-sectional area of the flow path of the intersection portion is gradually reduced. As a result, it is possible to reduce the pressure loss in a part of the first flow path, which is the portion to the intersection portion. In addition, the flow-path member in which the flow velocity in the intersection portion increases, and thus air bubbles can be prevented from remaining on the upper side of the connection portion between the first flow path and the second flow path is provided. As a result, it is possible to provide a liquid ejecting apparatus having a flow-path member in which pressure loss is reduced and excellent air-bubble discharge properties are ensured.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, details of embodiments of the invention will be described.

Details of embodiments of the invention will be described. An ink jet type recording head is an example of a liquid ejecting head and also referred to simply as a recording head. An ink jet type recording unit is an example of a liquid ejecting head unit and also referred to simply as a head unit. An ink jet type recording apparatus is an example of a liquid ejecting apparatus.FIG. 1is a perspective view illustrating the schematic configuration of an ink jet type recording apparatus according to this embodiment.

An ink jet type recording apparatus1is a so-called line type recording apparatus, as illustrated inFIG. 1. The ink jet type recording apparatus1includes a head unit101. In the ink jet type recording apparatus1, a recording sheet S, such as a paper sheet as an ejection target medium, is transported, in such a manner that printing is performed.

Specifically, the ink jet type recording apparatus includes an apparatus main body2, the head unit101, a transport unit4, and a support member7. The head unit101has a plurality of recording heads100. The transport unit4transports the recording sheet S. The support member7supports the recording sheet S facing the head unit101. In this embodiment, a transporting direction of the recording sheet S is set to an X direction. In a liquid ejection surface of the head unit101, in which nozzle openings are provided, a direction perpendicular to the X direction is set to a Y direction. A direction perpendicular to both the X direction and the Y direction is set to a Z direction. In this embodiment, the Z direction is parallel to a vertical direction. In the X direction, an upstream direction in which the recording sheet S is transported is set to an X1 direction and a downstream direction is set to an X2 direction. In the Y direction, one direction is set to a Y1 direction and the other is set to a Y2 direction. In the Z direction, a direction (toward the recording sheet S) parallel to a liquid ejecting direction is set to a Z1 direction and an opposite direction is set to a Z2 direction.

The head unit101includes a plurality of recording heads100and a head fixing substrate102which holds a plurality of recording heads100.

The plurality of recording heads100is fixed to the head fixing substrate102, in a state where the recording heads100are aligned in the Y direction intersecting the X direction which is the transporting direction. In this embodiment, the plurality of recording heads100are aligned in a straight line extending in the Y direction. In other words, the plurality of recording heads100are arranged so as not to be shifted toward the X direction. Accordingly, the X-direction width of head unit101is reduced, and thus it is possible to reduce the size of the head unit101.

The head fixing substrate102holds the plurality of recording heads100, in a state where the nozzle openings of the plurality of recording heads100are directed toward the recording sheet S. The head fixing substrate102holds a plurality of the recording heads100and is fixed to the apparatus main body2.

The transport unit4transports the recording sheet S in the X direction, with respect to the head unit101. The transport unit4includes a first transport roller5and a second transport roller6which are provided, in relation with the head unit101, for example, on both sides in the X direction as the transporting direction of the recording sheet S. The recording sheet S is transported, in the X direction, by the first transport roller5and the second transport roller6. The transport unit4for transporting the recording sheet S is not limited to a transport roller. The transport unit4may be constituted of a belt, a drum, or the like.

The support member7supports the recording sheet S transported by the transport unit4, at a position facing the head unit101. The support member7is constituted of, for example, a metal member or a resin member of which the cross-sectional surface has a rectangular shape. The support member7is disposed in an area between the first transport roller5and the second transport roller6, in a state where the support member7faces the head unit101.

An adhesion unit which is provided in the support member7and causes the recording sheet S to adhere thereto may be provided in the support member7. Examples of the adhesion unit include a unit which causes the recording sheet S to adhere thereto by sucking up the recording sheet S and a unit which causes the recording sheet S to be adhered thereto by electrostatically attracting the recording sheet S using electrostatic force. Furthermore, when the transport unit4is constituted of a belt or a drum, the support member7is located at a position facing the head unit101and causes the recording sheet S to be supported on the belt or the drum.

Although not illustrated, a liquid storage unit, such as an ink tank and an ink cartridge in which ink is stored, is connected to each recording head100of the head unit101, in a state where the liquid storage unit can supply ink to the recording head100. The liquid storage unit may be held on, for example, the head unit101. Alternatively, in the apparatus main body2, the liquid storage unit is held at a position separate from the head unit101. A flow path and the like through which the ink supplied from the liquid storage unit is supplied to the recording head100may be provided in the inner portion of the head fixing substrate102. Alternatively, an ink flow-path may be provided in the head fixing substrate102and ink from the liquid storage unit may be supplied to the recording head100through the ink flow-path member. Needless to say, ink may be directly supplied from the liquid storage unit to the recording head100, without passing through the head fixing substrate102or the ink flow-path member fixed to the head fixing substrate102.

In such an ink jet type recording apparatus1, the recording sheet S is transported, in the X direction, by the first transport roller5, and then the head unit101performs printing on the recording sheet S supported on the support member7. The recording sheet S subjected to printing is transported, in the X direction, by the second transport roller6.

Details of the head unit101will be described with reference toFIGS. 2 and 3.FIG. 2is an exploded perspective view illustrating the head unit according to this embodiment andFIG. 3is a bottom view of the head unit, when viewed from the liquid ejection surface side.

The head unit101of this embodiment includes a plurality of recording heads100and the head fixing substrate102which holds the plurality of recording heads100. In the recording head100, a liquid ejection surface20ain which the nozzle openings21are formed is provided on the Z1 side in the Z direction. Each recording head100is fixed to a surface of the head fixing substrate102, which is the surface facing the recording sheet S. In other words, the recording head100is fixed to the Z1 side, that is, the side facing the recording sheet S, of the head fixing substrate102in the Z direction.

As described above, the plurality of recording heads100are fixed to the head fixing substrate102, in a state where the recording heads100are aligned on a straight line extending in the Y direction perpendicular to the X direction which is the transporting direction. In other words, the plurality of recording heads100are arranged so as not to be shifted toward the X direction. Accordingly, the X-direction width of the head unit101is reduced, and thus it is possible to reduce the size of the head unit101. Needless to say, the recording heads100aligned in the Y direction may be arranged to be shifted toward the X direction. However, in this case, when the recording heads100are greatly shifted toward the X direction, for example, the X-direction width of the head fixing substrate102increases. When the X-direction size of the head unit101increases, as described above, the X-direction distance between the first transport roller5and the second transport roller6increases in the ink jet type recording apparatus1. As a result, it is difficult to fix the posture of the recording sheet S. In addition, the size of the head unit101and the ink jet type recording apparatus1increases.

In this embodiment, four recording heads100are fixed to the head fixing substrate102. However, the configuration is not limited thereto, as long as the number of recording heads100is two or more.

Next, the recording head100will be described with reference toFIG. 2andFIGS. 4 to 6.FIG. 4is a plan view of the recording head andFIG. 5is a bottom view of the recording head.FIG. 6is a cross-sectional view ofFIG. 4, taken along a line VI-VI.FIG. 4is a plan view of the recording head100, when viewed from the Z2 side in the Z direction. A holding member120is not illustrated inFIG. 4.

The recording head100includes the plurality of head main bodies110, COF substrates98, and a flow-path member200. The COF substrates98are respectively connected to the head main bodies110. Flow paths through which ink is supplied to respective head main bodies are provided in the flow-path member200. Furthermore, in this embodiment, the recording head100includes the holding member120, a fixing plate130, and a relay substrate140. The holding member120holds the plurality of head main bodies110. The fixing plate130is provided on the liquid ejection surface20aside of the head main body110.

The head main body110receives ink from the holding member120and the flow-path member200in which ink flow paths are provided. Control signals are transmitted from a controller (not illustrated) in the ink jet type recording apparatus1to the head main body110, via both the relay substrate140and the COF substrate98and the head main body110discharges ink droplets in accordance with the control signals. Details of the configuration of the head main body110will be described below.

In each head main body110, the liquid ejection surface20ain which nozzle openings21are formed is provided on the Z1 side in the Z direction. Z2 sides of the plurality of head main bodies110adhere to the Z1-side surface of the flow-path member200.

Liquid flow paths of ink supplied to the head main body110are provided in the flow-path member200. The plurality of head main bodies110adhere to the Z1-side surface of the flow-path member200, in a state where the plurality of head main bodies110are aligned in the Y direction. Details of the configuration of the flow-path member200will be described below. The liquid flow paths in the flow-path member200communicate with liquid flow paths of the respective head main bodies110, in such a manner that ink is supplied from the flow-path member200to the respective head main bodies110.

In this embodiment, six head main bodies110adhere to one flow-path member200. However, the number of head main bodies110fixed to one flow-path member200is not limited to six. One head main body110may be fixed to each flow-path member200or two or more head main bodies110may be fixed to each flow-path member200.

An opening portion201is provided in the flow-path member200, in a state where the opening portion201passes through the flow-path member200in the Z direction. The COF substrate98of which one end is connected to the head main body110is inserted through the opening portion201.

The COF substrate98is an example of a flexible wiring substrate. A flexible wiring substrate is a flexible substrate having wiring formed thereon. Furthermore, the COF substrate98includes a driving circuit97(seeFIG. 7) which drives a pressure generation unit in the head main body110.

The relay substrate140is a substrate on which electrical components, such as wiring, an IC, and a resistor, are mounted. The relay substrate140is disposed in a portion between the holding member120and the flow-path member200. A passing-through portion141communicating with the opening portion201in the flow-path member200is formed in the relay substrate140. The size of the opening of each passing-through portion141is greater than that of the opening portion201of the flow-path member200.

The COF substrate98connected to the pressure generation unit of the head main body110is inserted through both the opening portion201and the passing-through portion141. The COF substrate98is connected to a terminal (not illustrated) in the Z2-side surface of the relay substrate140. In other words, the COF substrates98are respectively connected to the head main bodies110. The COF substrate98extends from the Z1 side to the Z2 side in the Z direction. Furthermore, when viewed from the Y direction, all of the COF substrates98connected to the plurality of head main bodies110overlap each other. Although the COF substrate98of this embodiment is inclined, the lead electrode90and the relay substrate140which are electrically connected to the COF substrate98are arranged apart from each other in the Z direction, as described below. Thus the meaning of “the COF substrate98extends in the Z direction” includes the case in which the COF substrate98is inclined, as described above.

Although not particularly illustrated, the relay substrate140is connected to the controller of the ink jet type recording apparatus1. Accordingly, for example, the driving signals sent from the controller are transmitted, through the relay substrate140, to the driving circuit97of the COF substrate98. The pressure generation unit of the head main body110is driven by the driving circuit97. Therefore, an ink ejection operation of the recording head100is controlled.

On the Z1 side of the holding member120, a hold portion121is provided to form a space having a groove shape. On the Z1-side surface of the holding member120, the hold portion121continuously extends in the Y direction, and thus the hold portion121is open to both side surfaces of the holding member120in the Y direction. Furthermore, the hold portion121is provided in a substantially central portion of the holding member120in the X direction, and thus leg portions122are formed on both sides of the hold portion121in the X direction. In other words, in the Z1-side surface of the holding member120, the leg portions122are provided on only both end portions in the X direction and are not provided on both end portions in the Y direction. In this embodiment, the holding member120is constituted of one member. However, the configuration of the holding member120is not limited thereto. The holding member120may be constituted of a plurality of members stacked in the Z direction.

The relay substrate140, the flow-path member200, and the plurality of head main body110are accommodated in such a hold portion121. Specifically, the respective head main bodies110are bonded to the Z1-side surface of the flow-path member200, using, for example, an adhesive. Furthermore, the relay substrate140is fixed to the Z2-side surface of the flow-path member200. The relay substrate140, the flow-path member200, and the plurality of head main bodies110which are bonded into a single member are accommodated in the hold portion121.

In the holding member120and the flow-path member200, the Z-direction facing surfaces of the hold portion121and the flow-path member200adhere to each other, using an adhesive. The relay substrate140is accommodated in a space between the hold portion121and the flow-path member200. The holding member120and the flow-path member200may be integrally fixed using a fixing unit, such as a screw, instead of using an adhesive.

Although not particularly illustrated, a flow path through which ink flows, a filter which filters out, for example, foreign matter, and the like may be provided in the holding member120. The flow path of the holding member120communicates with the liquid flow path of the flow-path member200. Accordingly, the ink fed from the liquid storage unit in the ink jet type recording apparatus1is supplied to the head main body110via both the holding member120and the flow-path member200.

The fixing plate130is provided on the liquid ejection surface20aside of the recording head100. In other words, the fixing plate130is provided on the Z1 side of the recording head100in the Z direction and holds the respective recording heads100. The fixing plate130is formed by bending a plate-shaped member constituted of, for example, metal. Specifically, the fixing plate130includes a base portion131and bent portions132. The base portion131is provided on the liquid ejection surface20aside of the fixing plate130. Both end portions of the base portion131in the Y direction are bent in the Z2 direction, in such a manner that the bent portions132are formed.

Exposure opening portions133are provided in the base portion131. The exposure opening portions133are openings for exposing the nozzle openings21of the respective head main bodies110. In this embodiment, the exposure opening portions133are open in a state where the exposure opening portions133separately respectively correspond to the head main bodies110. In other words, the recording head100of this embodiment has the six head main bodies110, and thus six separate exposure opening portions133are provided in the base portion131. Needless to say, one common exposure opening portion133may be provided with respect to a head main body group constituted of a plurality of head main bodies110, in accordance with, for example, the configuration of the head main body110.

The Z1 side of the hold portion121of the holding member120is covered with such a base portion131. The base portion131is bonded, using an adhesive, to the Z1-side surface of the holding member120in the Z direction, in other words, the Z1-side end surfaces of the leg portion122, as illustrated inFIG. 6.

The bent portions132are provided on both end portions of the base portion131in the Y direction. The bent portions132have a size which is capable of covering the opening areas of the hold portion121, which are open in the Y-direction side surfaces of the hold portion121. In other words, the bent portion132is a portion extending from the Y-direction end portion of the base portion131to the edge portion of the fixing plate130. In addition, such a bent portion132is bonded, using an adhesive, to the Y-direction side surface of the holding member120. Accordingly, the openings of the hold portion121, which are open in the Y-direction side surfaces of the hold portion121, are covered and sealed with the bent portions132.

The fixing plate130adheres, using an adhesive, to the holding member120, as described above, and thus the head main body110is disposed in the inner portion of the hold portion121, which is a space between the holding member120and the fixing plate130.

The plurality of head main bodies110are provided in each recording head100, in such a manner that the recording head100of this embodiment has a plurality of nozzle rows, as described above. In this case, it is possible to improve a yield, compared to in a case where a plurality of nozzle rows are provided in only one head main body110, in such a manner that one recording head100has a plurality of nozzle rows. In other words, when a plurality of nozzle rows are provided by one head main body110, the yield of the head main body110decreases and a manufacturing cost increases. In contrast, when a plurality of nozzle rows are provided by a plurality of head main bodies110, the yield of the head main body110is improved and the manufacturing cost can be reduced.

The openings in the Y-direction side surfaces of the holding member120are sealed with the bent portions132of the fixing plate130. Accordingly, even when leg portions122which adhere to the base portion131of the fixing plate130are not provided on both sides (which are hatched portions inFIG. 3) of the holding member120in the Y direction, it is possible to prevent moisture evaporation from occurring through the openings in the Y-direction side surfaces of the hold portion121.

Accordingly, in the head unit101in which the recording heads100are aligned in the Y direction, a gap between adjacent recording heads100in the Y direction can be reduced because the leg portions122are not provided on the Y-direction sides of the adjacent recording heads100. Accordingly, the head main bodies110of adjacent recording heads100in the Y direction can be arranged close to each other, and thus the nozzle openings21of the respective head main bodies110of the adjacent recording heads100can be arranged close to each other in the Y direction.

In the recording head100according to this embodiment, the leg portions122are provided on both sides of the holding member120in the X direction. However, the leg portions122may not be provided. In other words, the head main body110may adhere to the Z1-side surface of the holding member120and the bent portions132may be provided on both sides of the fixing plate130in the X direction and on both sides thereof in the Y direction. That is, the bent portions132may be provided over the circumference of the fixing plate130, in an in-plane direction of the liquid ejection surface20a, and the fixing plate130adheres over the circumference of the side surfaces of the holding member120. However, when the leg portions122are provided on both sides of the holding member120in the X direction, as in the case of this embodiment, the Z1-side end surfaces of the leg portion122adhere to the base portion131of the fixing plate130. As a result, the hardness of the ink jet type recording head100in the Z direction can be improved and it is possible to prevent moisture evaporation from occurring through the leg portions122.

The head main body110will be described with reference toFIGS. 7 and 8.FIG. 7is a perspective view of the head main body according to this embodiment andFIG. 8is a cross-sectional view of the head main body, taken along a line extending in the Y direction. Needless to say, the configuration of the head main body110is not limited to the configuration described below.

The head main body110of this embodiment includes a pressure generation chamber12, the nozzle openings21, a manifold95, the pressure generation unit, and the like. Therefore, a plurality of members, such as a flow-path forming substrate10, a communication plate15, a nozzle plate20, a protection substrate30, a compliance substrate45, a case40and the like are bonded to one another, using, for example, an adhesive.

One surface side of the flow-path forming substrate is subjected to anisotropic etching, in such a manner that a plurality of pressure generation chambers12partitioned by a plurality of partition walls are provided in the flow-path forming substrate10, in a state where the pressure generation chambers12are aligned in an alignment direction of a plurality of the nozzle openings21. In this embodiment, the alignment direction of the pressure generation chambers12is referred to as the Xa direction. Furthermore, a plurality (two, in this embodiment) of rows, each of which is constituted of the pressure generation chambers12aligned in the Xa direction, are provided in the flow-path forming substrate10. A row-alignment direction in which a plurality of rows of the pressure generation chambers12are aligned will be referred to as a Ya direction. In this embodiment, a direction perpendicular to both the Xa direction and the Ya direction is parallel to the Z direction. Furthermore, the head main body110of this embodiment is mounted on the head unit101, in a state where the Xa direction as an alignment direction of the nozzle openings21is inclined with respect to the X direction as the transporting direction of the recording sheet S.

For example, a supply path of which the opening area is smaller than that of the pressure generation chamber and which imparts a flow-path resistance to the ink flowing to the pressure generation chamber12may be provided in the flow-path forming substrate10in one end side of the Ya direction of the pressure generation chamber12.

The communication plate15is bonded to one surface side of the flow-path forming substrate10. Furthermore, the nozzle plate20in which a plurality of nozzle openings communicating with the respective pressure generation chambers12are provided is bonded to the communication plate15. In this embodiment, the Z1 side of the nozzle plate20, on which the nozzle openings21are open, is the liquid ejection surface20a.

A nozzle communication path16which allows the pressure generation chamber12to communicate with the nozzle opening21is provided in the communication plate15. The area of the communication plate15is greater than that of the flow-path forming substrate10and the area of the nozzle plate20is smaller than that of the flow-path forming substrate10. The nozzle plate20has a relatively small area, as described above. As a result, it is possible to achieve a reduction in costs.

A first manifold17and a second manifold18which constitute a part of the manifold95is provided in the communication plate15. The first manifold17passes through the communication plate15in the Z direction. The second manifold18does not pass through the communication plate15in the Z direction. The second manifold18is open to the nozzle plate20side of the communication plate15and extends to the Z-direction middle portion of the nozzle plate20.

Supply communication paths19which communicate with respective end portions of the pressure generation chambers12in the Y direction is provided in the communication plate15, in a state where the supply communication paths19separately respectively correspond to the pressure generation chambers12. The supply communication path19allows the second manifold18to communicate with the pressure generation chamber12.

The nozzle openings21which respectively communicate with the pressure generation chambers12through the nozzle communication path16are formed in the nozzle plate20. The plurality of nozzle openings21are aligned in the Xa direction. The aligned nozzle openings21form two nozzle rows which are a nozzle row a and a nozzle row b. The nozzle row a and the nozzle row b are aligned in the Ya direction. In this embodiment, each of the nozzle rows a and b is divided into two portions, and thus one nozzle row can eject liquids of two kinds. Details of this will be described below.

Meanwhile, a diaphragm50is formed on a surface of the flow-path forming substrate10, which is the surface on the side opposite to the communication plate15of the flow-path forming substrate10. A first electrode60, a piezoelectric layer70, and a second electrode80are laminated, in order, on the diaphragm50, in such a manner that a piezoelectric actuator300as the pressure generation unit of this embodiment is constituted. Generally, one electrode of the piezoelectric actuator300is constituted of a common electrode. The other electrodes and the piezoelectric layers are subjected to patterning such that the other electrode and the piezoelectric layer correspond to each pressure generation chamber12.

The protection substrate30having substantially the same size as that of the flow-path forming substrate10is bonded to a surface of the flow-path forming substrate10, which is the surface on the piezoelectric actuator300side. The protection substrate30has a hold portion31which is a space for protecting the piezoelectric actuator300. Furthermore, in the protection substrate30, a through-hole32is provided in a state where the through-hole32passes through the protection substrate30in the Z direction. An end portion of a lead electrode90extending from the electrode of the piezoelectric actuator300extends such that the end portion is exposed to the inner portion of the through-hole32. The lead electrode90and the COF substrate98are electrically connected in the through-hole32.

Furthermore, the case40which forms manifolds95communicating with a plurality of pressure generation chambers12is fixed to both the protection substrate30and the communication plate15. In a plan view, the case40and the communication plate15described above have the substantially the same shape. The case40is bonded to the protection substrate30and, further, bonded to the communication plate15described above. Specifically, a concave portion41is provided on the protection substrate30side of the case40. The depth of the concave portion41is enough to accommodate both the flow-path forming substrate10and the protection substrate30. The opening area of the concave portion41is greater than that of a surface of the protection substrate30, which is the surface bonded to the flow-path forming substrate10. An opening surface of the concave portion41, which is the opening surface on the nozzle plate20side, is sealed with the communication plate15, in a state where the flow-path forming substrate10and the like are accommodated in the concave portion41. Accordingly, in the outer circumferential portion of the flow-path forming substrate10, a third manifold42is formed by the case40, the flow-path forming substrate10, and the protection substrate30. The manifold95of this embodiment is constituted of the third manifold42, the first manifold17, and the second manifold18, in which the first manifold17and the second manifold18are provided in the communication plate15. Liquids of two kinds can be ejected by one nozzle row, as described above. Thus, each of the first manifold17, the second manifold18, and the third manifold42which constitute the manifold95is divided into two portions, in a nozzle-row direction, that is, the Xa direction. The first manifold17is constituted of, for example, a first manifold17aand a first manifold17b, as illustrated inFIG. 7. Similarly, each of the second manifold18and the third manifold42is also divided into two portions. Thus, the entirety of the manifold95is divided into two portions, in the Xa direction.

In this embodiment, the first manifolds17, the second manifolds18, and the third manifolds42which constitute the manifolds95are symmetrically arranged with the nozzle rows a and b interposed therebetween. In this case, the nozzle row a and the nozzle row b can eject different liquids. Needless to say, the arrangement of the manifolds is not limited thereto.

In this embodiment, each of the manifolds corresponding to the respective nozzle rows is divided into two portions, in the Xa direction. Accordingly, in total, four manifolds95are provided such that liquids of four kinds can be ejected, as described below. However, manifolds may be provided corresponding to nozzle rows a and b. Alternatively, one common manifold may be provided with respect to the two rows which are the nozzle row a and the nozzle row b.

The compliance substrate45is provided in a surface of the communication plate15, in which both the first manifold17and the second manifold18are open. The openings of both the first manifold17and the second manifold18are sealed with the compliance substrate45.

In this embodiment, such a compliance substrate45includes a sealing film46and a fixing substrate47. The sealing film46is constituted of a flexible thin film (which is formed of, for example, polyphenylene sulfide (PPS) or stainless steel (SUS)). The fixing substrate47is constituted of a hard material, for example, metal, such as stainless metal (SUS). A part of the fixing substrate47, which is the portion facing the manifold95, is completely removed in a thickness direction and forms an opening portion48. Thus, one surface of the manifold95forms a compliance portion49which is a flexible portion sealed with only the sealing film46having flexibility.

The fixing plate130adheres to a surface of the compliance substrate45, which is the surface on a side opposite to the communication plate15. In other words, the opening area of the exposure opening portion133of the base portion131of the fixing plate130is a greater than the area of the nozzle plate20. The liquid ejection surface20aof the nozzle plate20is exposed through the exposure opening portion133. Needless to say, the configuration is not limited thereto. The opening area of the exposure opening portion133of the fixing plate130may be smaller than that of the nozzle plate20and the fixing plate130may abut or adhere to the liquid ejection surface20aof the nozzle plate20. Alternatively, even when the opening area of the exposure opening portion133of the fixing plate130is smaller than that of the nozzle plate20, the fixing plate130may be provided in a state where the fixing plate130is not in contact with the liquid ejection surface20a. In other words, the meaning of “the fixing plate130is provided on the liquid ejection surface20aside” includes both a state where the fixing plate130is not in contact with the liquid ejection surface20aand a state where the fixing plate130is in contact with the liquid ejection surface20a.

An introduction path44is provided in the case40. The introduction path44communicates with the manifold95and allows ink to be supplied to the manifold95. In addition, a connection port43is provided in the case40. The connection port43communicates with the through-hole32of the protection substrate30and the COF substrate98is inserted therethrough.

In the head main body110configured as described above, when ink is ejected, ink is fed from a storage unit through the introduction path44and the flow path from the manifold95to the nozzle openings21is filled with the ink. Then, voltage is applied, in accordance with signals from the driving circuit97, to each piezoelectric actuator300corresponding to the pressure generation chamber12, in such a manner that the diaphragm, along with the piezoelectric actuator300, is flexibly deformed. As a result, the pressure in the pressure generation chamber12increases, and thus ink droplets are ejected from predetermined nozzle openings21.

Here, details of the configuration in which the alignment direction of the nozzle openings21constituting the nozzle row of the head main body110is inclined with respect to the X direction as the transporting direction of the recording sheet S will be described with reference toFIGS. 5 and 9.FIG. 9is a schematic view explaining the arrangement of the nozzle openings of the head main body according to this embodiment.

The plurality of the head main bodies110are fixed in a state where, in the in-plane direction of the liquid ejection surface20a, the nozzle rows a and b are inclined with respect to the X direction as the transporting direction of the recording sheet S. The nozzle row referred to in this case is a row of a plurality of nozzle openings21aligned in a predetermined direction. In this embodiment, two rows which are the nozzle rows a and b, each of which is constituted of a plurality of nozzle openings21aligned in the Xa direction as the predetermined direction, are provided in the liquid ejection surface20a. The Xa direction intersects the X direction at an angle greater than 0° and less than 90°. In this case, it is preferable that the Xa direction intersects the X direction at an angle greater than 0° and less than 45°. In this case, upon comparison with in the case where the Xa direction intersects the X direction at an angle greater than 45° and less than 90°, a gap D1between adjacent nozzle openings21in the Y direction can be further reduced. As a result, the recording head100can have high definition in the Y direction. Needless to say, the Xa direction may intersect the X direction at an angle greater than 45° and less than 90°.

The meaning of “the Xa direction intersects the X direction at the angle greater than 0° and less than 45°” implies that, in the plane of the liquid ejection surface20a, the nozzle row is inclined closer to the X direction than a straight line intersecting the X direction at 45°. The gap D1referred to in this case is a gap between the nozzle openings21of the nozzle rows a and b, in a state where the nozzle openings21are projected in the X direction, with respect to an imaginary line in the Y direction. Furthermore, a gap between the nozzle openings21of the nozzle rows a and b which are projected in the Y direction, with respect to an imaginary line in the X direction, is set to a gap D2.

In this embodiment, liquids of two kinds can be ejected from one nozzle row and liquids of four kinds can be ejected from two nozzle rows, as illustrated inFIG. 9. In other words, when it is assumed that inks of four colors are used, a black ink Bk and a magenta ink M are can be ejected from the nozzle row a and a cyan ink C and a yellow ink Y can be ejected from the nozzle row b. Furthermore, the nozzle row a and the nozzle row b have the same number of nozzle openings21. The Y-direction positions of the nozzle openings21of the nozzle row a and the Y-direction positions of the nozzle openings21of the nozzle row b overlap in the X direction.

Head main bodies110ato110chave the nozzle rows a and b. The head main bodies110ato110bare arranged close to each other in the Y direction, and thus the nozzle openings21of adjacent head main bodies110in the Y direction are aligned in a state where the nozzle openings21overlap in the X direction. Accordingly, a part of the nozzle row a of the head main body110a, which is a portion ejecting the magenta ink M, and a part of the nozzle row b of the head main body110a, which is a portion ejecting the yellow ink Y, overlap, in the X direction, with a part of the nozzle row a of the head main body110b, which is a portion ejecting the black ink Bk, and a part of the nozzle row b of the head main body110b, which is a portion ejecting the cyan ink C. Therefore, lines of four colors are aligned in one row in the X direction, and thus a color image can be printed. Similarly, in the case of adjacent head main bodies110band110cin the Y direction, the nozzle openings21are aligned in a state where the nozzle openings21overlap in the X direction.

At least some of nozzle openings21of nozzle rows of adjacent head main bodies110, which are the nozzle rows ejecting ink of the same color, overlap in the X direction. As a result, the image quality in a joining portion between the head main bodies110can be improved. In other words, one nozzle opening21of the nozzle row a of the head main body110a, which is the nozzle row ejecting the magenta ink M, and one nozzle opening21of the nozzle row a of the head main body110b, which is the nozzle row ejecting the magenta ink M, overlap in the X direction. Ejection operations through the two overlapping nozzle openings21are controlled, in such a manner that image quality deterioration, such as banding and streaks, can be prevented from occurring in the joining portion between the adjacent head main bodies110. In an example illustrated inFIG. 9, only one nozzle opening21of one head main body110and one nozzle openings21of the other head main body110overlap in the X direction. However, two or more nozzle openings21of one head main body110and two or more nozzle openings21of the other head main body110may overlap in the X direction.

Needless to say, the arrangement relating to colors may not be limited thereto. Although not particularly illustrated, the black ink Bk, the magenta ink M, the cyan ink C, and the yellow ink Y can be ejected from, for example, one nozzle row.

As described above, the head unit101is constituted by fixing four recording heads100to the head fixing substrate102, in which each recording head100has a plurality of head main bodies110. Parts of nozzle rows of adjacent recording heads100overlap in the X direction, as illustrated by a straight line L inFIG. 5. In other words, similarly to the relationship between adjacent head main bodies110in one recording head100, adjacent head main bodies110of adjacent recording heads100in the Y direction are arranged close to each other in the Y direction, and thus a color image can be printed in a portion between the adjacent recording heads100and, further, the image quality in the joining portion between the adjacent recording heads100can be improved. Needless to say, the number of overlapping nozzle openings21between adjacent recording heads100, which overlap in the X direction, is not necessarily the same as the number of overlapping nozzle openings21between adjacent head main bodies110in one recording head100, which overlap in the X direction.

As described above, the nozzle rows between adjacent head main bodies110the nozzle rows between adjacent recording heads100partially overlap in the X direction, and thus the image quality in the joining portion can be improved.

It is preferable that, in a portion between nozzle openings21of nozzle rows, which are adjacent in the Xa direction, a pitch between adjacent nozzles and the an angle between the X direction and the Xa direction are set to satisfy a condition in which the relationship between the gap D1in the X direction and the gap D2in the Y direction satisfies an integer ratio. In this case, when an image is printed in accordance with image data which is constituted of pixels having a matrix shape in which the pixels are arranged in both the X direction and the Y direction, it is easy to pair each nozzle with each pixel. Needless to say, the relationship is not limited to the relationship of an integer ratio.

In a plan view seen from the liquid ejection surface20aside, the recording head100of this embodiment has a substantially parallelogram shape, as illustrated inFIG. 5. The reason for this is as follows. The Xa direction as the alignment direction of the nozzle openings21which constitute the nozzle rows a and b of each head main body110is inclined with respect to the X direction as the transporting direction of the recording sheet S. Furthermore, the recording head100is formed in a shape parallel to the Xa direction as an inclined direction of the nozzle row b. In other words, the fixing plate130has a substantially parallelogram shape. Needless to say, in a plan view seen from the liquid ejection surface20aside, the shape of the recording head100is not limited to a substantially parallelogram. The recording head100may have a trapezoidal-rectangular shape, a polygonal shape, or the like.

An example in which two nozzle rows are provided in one head main body is described in the embodiment described above. However, needless to say, even when three or more nozzle rows are provided, the same effects described above may be obtained. Furthermore, when two nozzle rows are provided in one head main body110, as in the case of this embodiment, nozzle openings21of the two nozzle rows can be arranged in a portion between two manifolds95respectively corresponding to the two nozzle rows, as illustrated inFIG. 8. Thus, a gap between the two nozzle rows in the Ya direction can be reduced, compared to in the case where nozzle openings21of a plurality of nozzle rows are arranged on the same side with respect to manifolds respectively corresponding to the plurality of nozzle rows. As a result, in the nozzle plate20, the area required for providing two nozzle rows can be reduced. In addition, it is easy to connect the respective piezoelectric actuators300corresponding to two nozzle rows and the respective COF substrates98.

In this embodiment, the nozzle row a and the nozzle row b have the same number of nozzle openings21. Accordingly, in the nozzle rows, the same number of nozzle openings21can overlap in the X direction, and thus it is possible to effectively eject liquid. However, nozzle rows do not have necessarily the same number of nozzle openings. Furthermore, the nozzle rows a and b may eject liquids of the same kind. In other words, the nozzle rows a and b may eject, for example, ink of the same color.

In this embodiment, it is preferable that the head main body110has s nozzle plate20having two nozzle rows. In this case, nozzle rows can be arranged with higher precision. Needless to say, one nozzle row may be provided in each nozzle plate20. The nozzle plate20is constituted of a stainless-steel (SUS) plate, a silicon substrate, or the like.

Details of the flow-path member200according to this embodiment will be described with reference toFIGS. 10 to 16.FIG. 10is a plan view of a first flow-path member210as the flow-path member200,FIG. 11is a plan view of a second flow-path member220as the flow-path member200, andFIG. 12is a plan view of a third flow-path member230as the flow-path member200.FIG. 13is a bottom view of the third flow-path member.FIG. 14is a cross-sectional view ofFIGS. 10 to 13, taken along a line XIV-XIV, andFIG. 15is a cross-sectional view ofFIGS. 10 to 13, taken along a line XV-XV.FIG. 16is a cross-sectional view ofFIGS. 10 to 15, taken along a line XVI-XVI.FIGS. 10 to 12are plan views seen from the Z2 side andFIG. 13is a bottom view seen from the Z1 side.

A flow path240through which ink flows is provided in the flow-path member200. In this embodiment, the flow-path member200includes three flow-path members stacked in the Z direction and a plurality of flow paths240. The three flow-path members are a first flow-path member (which corresponds to a first member of the invention)210, a second flow-path member (which corresponds to a second member of the invention)220, and a third flow-path member (which corresponds to a third member of the invention)230. In the Z direction, the first flow-path member210, the second flow-path member220, and the third flow-path member230are stacked in order from the holding member120side (seeFIG. 2) to the head main body110side. Although not particularly illustrated, the first flow-path member210, the second flow-path member220, and the third flow-path member230are fixed in an adhesive manner, using an adhesive. However, the configuration is not limited thereto. The first flow-path member210, the second flow-path member220, and the third flow-path member230may be fixed to each other, using a fixing unit, such as a screw. Furthermore, although the material forming the flow-path member is not particularly limited, the flow-path member can be constituted of, for example, metal, such as SUS, or resin.

In the flow path240, one end is an introduction flow path280and the other end is a connection portion290. Ink supplied from a member (which is the holding member120, in this embodiment) upstream from the flow path240is introduced through the introduction flow path280. The connection portion290functions as an output port through which the ink is supplied to the head. In this embodiment, four flow paths240are provided. In each flow path240, ink is supplied to one introduction flow path280. In the middle of each flow path240, the flow path240branches into a plurality of flow paths. Therefore, in each flow path240, the ink is supplied to the head main body110through a plurality of connection portions290.

Some of the four flow paths240are first flow paths241and the others are second flow paths242. In this embodiment, two first flow paths241and two second flow paths242are provided. One of the two first flow paths241is referred to as a first flow path241aand the other is referred to as a first flow path241b. Hereinafter, the first flow path241indicates both the first flow path241aand the first flow path241b. The second flow path242has a similar configuration to that described above.

The first flow path241includes a first introduction flow path281. The first introduction flow path281connects a first distribution flow path251of the first flow path241and a flow path (which is the flow path of the holding member120, in this embodiment) upstream from the flow-path member200. The first distribution flow path251will be described below. In this embodiment, each of two first flow paths241aand241bhas a first introduction flow path281aand a first introduction flow path281b.

Specifically, the first introduction flow path281ais constituted of a through-hole211and a through-hole221which communicate with each other. The through-hole211is open to the top surface of a protrusion portion212which is provided on the Z2-side surface of the first flow-path member210and the through-hole211passes through, in the Z direction, both the first flow-path member210and the protrusion portion212. The through-hole221passes through the second flow-path member220in the Z direction. The first introduction flow path281bhas a similar configuration to that described above. Hereinafter, the first introduction flow path281indicates both the first introduction flow path281aand the first introduction flow path281b.

The second flow path242includes a second introduction flow path282. The second introduction flow path282connects a second distribution flow path252of the second flow path242and a flow path (which is the flow path of the holding member120, in this embodiment) upstream from the flow-path member200. The second distribution flow path252will be described below. In this embodiment, each of two first flow paths242aand242bhas a second introduction flow path282aand a second introduction flow path282b.

Specifically, the second introduction flow path282ais a through-hole open on the top surface of a protrusion portion212which is provided on the Z2-side surface of the first flow-path member210. The second introduction flow path282apasses through, in the Z direction, both the first flow-path member210and the protrusion portion212. The second introduction flow path282bhas a similar configuration to that described above. Hereinafter, the second introduction flow path282indicates both the second introduction flow path282aand the second introduction flow path282b.

The introduction flow path280indicates all of the four introduction flow paths described above. The introduction flow path280corresponds to an inlet port of the invention.

In this embodiment, in a plan view illustrated inFIG. 10, the first introduction flow path281ais disposed in the vicinity of an upper left corner of the first flow-path member210and the first introduction flow path281bis disposed in the vicinity of a lower right corner of the first flow-path member210. In the plan view illustrated inFIG. 10, the second introduction flow path282ais disposed in the vicinity of a upper right corner of the first flow-path member210and the second introduction flow path282bis disposed in the vicinity of a lower left corner of the first flow-path member210.

The first flow path241includes the first distribution flow path251which is formed by both the second flow-path member220and the third flow-path member230. The first distribution flow path251is a part of the first flow path241, through which ink flows in a direction parallel to the liquid ejection surface20a. In this embodiment, two first flow paths241are formed, and thus two first distribution flow paths251are formed. One of the two first distribution flow paths251is referred to as a first distribution flow path251aand the other is referred to as a first distribution flow path251b.

An intersection groove portion226aand an intersection groove portion231aare matched and sealed, in such a manner that the first distribution flow path251ais formed. The intersection groove portion226ais formed on the Z1-side surface of the second flow-path member220and extends in the Y direction. The intersection groove portion231ais formed on the Z2-side surface of the third flow-path member230and extends in the Y direction. An intersection groove portion226band an intersection groove portion231bare matched and sealed, in such a manner that the first distribution flow path251bis formed. The intersection groove portion226bis formed on the Z1-side surface of the second flow-path member220and extends in the Y direction. The intersection groove portion231bis formed on the Z2-side surface of the third flow-path member230and extends in the Y direction.

The first distribution flow path251ais constituted of both the intersection groove portions226ain the second flow-path member220and the intersection groove portion231ain the third flow-path member230and the first distribution flow path251bis constituted of both the intersection groove portion226bin the second flow-path member220and the intersection groove portion231bin the third flow-path member230. As a result, the cross-sectional areas of the first distribution flow paths251aand251bare widened, and thus pressure losses in the first distribution flow paths251aand251bare reduced. The first distribution flow path251amay be constituted of only the intersection groove portion226ain the second flow-path member220and the first distribution flow path251bmay be constituted of only the intersection groove portion226bin the second flow-path member220. Alternatively, the first distribution flow path251amay be constituted of only the intersection groove portion231ain the third flow-path member230and the first distribution flow path251bmay be constituted of only the intersection groove portion231bin the third flow-path member230. The intersection groove portions226aand226bare formed in only the second flow-path member220on the Z2 side, in such a manner that the degree of freedom in the arrangement of the first flow path241can be improved while preventing the first distribution flow paths251aand251bfrom interfering with the COF substrate98of which the Xa-direction width is reduced as the COF substrate98extends from the Z1 side to the Z2 side, as described below.

The first distribution flow path251aand the first distribution flow path251bare disposed in both areas located X-directionally outside the opening portion201(in other words, a third opening portion235) through which the COF substrate98is inserted.

The second flow path242includes the second distribution flow path252which is formed by both the first flow-path member210and the second flow-path member220. The second distribution flow path252is a part of the second flow path242, through which ink flows in a direction parallel to the liquid ejection surface20a. In this embodiment, two second flow paths242are formed, and thus two second distribution flow paths252are formed. One of the two second distribution flow paths252is referred to as a second distribution flow path252aand the other is referred to as a second distribution flow path252b.

An intersection groove portion213aand an intersection groove portion222aare matched and sealed, in such a manner that the second distribution flow path252ais formed. The intersection groove portion213ais formed on the Z1-side surface of the first flow-path member210and extends in the Y direction. The intersection groove portion222ais formed on the Z2-side surface of the second flow-path member220and extends in the Y direction. An intersection groove portion213band an intersection groove portion222bare matched and sealed, in such a manner that the second distribution flow path252bis formed. The intersection groove portion213bis formed on the Z1-side surface of the first flow-path member210and extends in the Y direction. The intersection groove portion222bis formed on the Z2-side surface of the second flow-path member220and extends in the Y direction.

The second distribution flow path252ais constituted of both the intersection groove portions213ain the first flow-path member210and the intersection groove portion222ain the second flow-path member220and the second distribution flow path252bis constituted of both the intersection groove portion213bin the first flow-path member210and the intersection groove portion222bin the second flow-path member220. As a result, the cross-sectional areas of the second distribution flow paths252aand221bare widened, and thus pressure losses in the second distribution flow paths252aand252bare reduced. The second distribution flow path252amay be constituted of only the intersection groove portion2136ain the first flow-path member210and the second distribution flow path252bmay be constituted of only the intersection groove portion213bin the first flow-path member210. Alternatively, the second distribution flow path252amay be constituted of only the intersection groove portion222ain the second flow-path member220and the second distribution flow path252bmay be constituted of only the intersection groove portion222bin the second flow-path member220. The intersection groove portions222aand222bare formed in only the first flow-path member210on the Z2 side, in such a manner that, similarly to in the case of the first distribution flow paths251aand251bdescribed above, the degree of freedom in the arrangement of the second flow path242can be improved while preventing the second distribution flow paths252aand252bfrom interfering with the COF substrate98.

The second distribution flow path252aand the second distribution flow path252bare disposed in both areas located X-directionally outside the opening portion201(in other words, a second opening portion225) through which the COF substrate98is inserted.

Hereinafter, the first distribution flow path251indicates both the first distribution flow path251aand the first distribution flow path251b. Furthermore, the second distribution flow path252indicates both the second distribution flow path252aand the second distribution flow path252b. In addition, the distribution flow path250indicates all of the four distribution flow paths described above.

In the first flow path241of this embodiment, one introduction flow path280branches into a plurality of connection portions290. In other words, the first distribution flow path251branches into a plurality of first bifurcation flow paths (which correspond to first flow paths of the invention)261, in the same surface (which is a boundary surface in which the second flow-path member220and the third flow-path member230are bonded to each other) with the first distribution flow path251.

In this embodiment, the first distribution flow path251branches into six first bifurcation flow paths261, in the surface (which is a boundary surface between the second flow-path member220and the third flow-path member230) parallel to the liquid ejection surface20a. The six first bifurcation flow paths261branching off from the first distribution flow path251aare referred to as first bifurcation flow paths261a1to261a6. Hereinafter, the first bifurcation flow path261aindicates all of the six bifurcation flow paths connected to the first bifurcation flow path261a.

Similarly, six first bifurcation flow paths261branching off from the first distribution flow path251bare referred to as first bifurcation flow paths261b1to261b6. Hereinafter, the first bifurcation flow path261bindicates all of the six bifurcation flow paths connected to the first bifurcation flow path261b. In addition, the first bifurcation flow path261indicates all of the twelve bifurcation flow paths connected to the first bifurcation flow paths261aand261b.

Reference letters and numerals corresponding to the first bifurcation flow paths261a2to261a5of the six first bifurcation flow paths261a1to261a6aligned in the Y direction are omitted in the accompanying drawings. However, it is assumed that the first bifurcation flow paths261a2to261a5are aligned in order from the Y1 side to the Y2 side. The first bifurcation flow paths261b1to261b6have a similar configuration to that described above.

Specifically, a plurality of branch groove portions232awhich communicate with the intersection groove portion231aand extend to the opening portion201side are provided in the Z2-side surface of the third flow-path member230. A plurality of branch groove portions227awhich communicate with the intersection groove portion226aand extend to the opening portion201side are provided in the Z1-side surface of the second flow-path member220. The branch groove portion227aand the branch groove portion232aare sealed in a state where the branch groove portion227aand the branch groove portion232aface each other, in such a manner that the first bifurcation flow path261ais formed.

A plurality of branch groove portions232bwhich communicate with the intersection groove portion231band extend to the opening portion201side are provided in the Z2-side surface of the third flow-path member230. A plurality of branch groove portions227bwhich communicate with the intersection groove portion226band extend to the opening portion201side are provided in the Z1-side surface of the second flow-path member220. The branch groove portion227band the branch groove portion232bare sealed in a state where the branch groove portion227band the branch groove portion232bface each other, in such a manner that the first bifurcation flow path261bis formed.

The first bifurcation flow path261ais constituted of both the branch groove portions227ain the second flow-path member220and the branch groove portion232ain the third flow-path member230and the first bifurcation flow path261bis constituted of both the branch groove portion227bin the second flow-path member220and the branch groove portion232bin the third flow-path member230. As a result, the cross-sectional areas of the first bifurcation flow paths261aand261bare widened, and thus pressure losses in the first bifurcation flow paths261aand261bare reduced. The first bifurcation flow path261amay be constituted of only the branch groove portion227ain the second flow-path member220and the first bifurcation flow path261bmay be constituted of only the branch groove portion227bin the second flow-path member220. Alternatively, the first bifurcation flow path261amay be constituted of only the branch groove portion232ain the third flow-path member230and the first bifurcation flow path261bmay be constituted of only the branch groove portion232bin the third flow-path member230. For example, the branch groove portions227aand227bare formed in only the second flow-path member220on the Z2 side. As a result, in an area Q which is inclined in the Ya direction, and thus the Ya-direction width increases as the area Q extends from the Z1 side to the Z2 side, as described below, the degree of freedom in the arrangement of the first flow path241can be improved while preventing interference with the COF substrate98. Furthermore, the branch groove portions232aand232bare formed in only the third flow-path member230on the Z1 side. As a result, in an area P of which the width in the Ya direction increases as the area P extends from the Z2 side to the Z1 side, the degree of freedom in the arrangement of the first flow path241can be improved while preventing interference with the COF substrate98.

In the second flow path242, one introduction flow path280branches into a plurality of connection portions290. The second distribution flow path252branches into a plurality of second bifurcation flow paths (which correspond to the first flow paths of the invention)262, in the same surface (which is a boundary surface in which the first flow-path member210and the second flow-path member220are bonded to each other) with the second distribution flow path252. Details of this will be described below.

In this embodiment, the second distribution flow path252branches into six second bifurcation flow paths262, in the surface (which is a boundary surface between the first flow-path member210and the second flow-path member220) parallel to the liquid ejection surface20a. The six second bifurcation flow paths262branching off from the second distribution flow path252aare referred to as second bifurcation flow paths262a1to262a6.

Similarly, six second bifurcation flow paths262branching off from the second distribution flow path252bare referred to as second bifurcation flow paths262b1to262b6.

Hereinafter, the second bifurcation flow path262aindicates all of the six bifurcation flow paths connected to the second bifurcation flow path262a. The second bifurcation flow path262bindicates all of the six bifurcation flow paths connected to the second bifurcation flow path262b. The second bifurcation flow path262indicates all of the twelve bifurcation flow path connected to the second bifurcation flow paths262aand262b. Furthermore, the bifurcation flow path260indicates all of the twenty-four bifurcation flow paths described above.

Reference letters and numerals corresponding to second bifurcation flow paths262a2to262a5of the six second bifurcation flow paths262a1to262a6aligned in the Y direction are omitted in the accompanying drawings. However, it is assumed that the second bifurcation flow paths262a2to262a5are aligned in order from the Y1 side to the Y2 side. The second bifurcation flow paths262b1to262b6have a similar configuration to that described above.

Specifically, a plurality of branch groove portions223awhich communicate with the intersection groove portions222aand extend to the opening portion201side are provided in the Z2-side surface of the second flow-path member220. In addition, a plurality of branch groove portions214awhich communicate with the intersection groove portions213aand extend to a side opposite to the opening portion201side are provided in the Z1-side surface of the first flow-path member210. The branch groove portion223aand the branch groove portion214aare sealed in a state where the branch groove portion223aand the branch groove portion214aface each other, in such a manner that the second bifurcation flow path262ais formed.

A plurality of branch groove portions223bwhich communicate with the intersection groove portions222band extend to the opening portion201side are provided in the Z2-side surface of the second flow-path member220. In addition, a plurality of branch groove portions214bwhich communicate with the intersection groove portions213band extend to the opening portion201side are provided in the Z1-side surface of the first flow-path member210. The branch groove portion223band the branch groove portion214bare sealed in a state where the branch groove portion223band the branch groove portion214bface to each other, in such a manner that the second bifurcation flow path262bis formed.

The second bifurcation flow path262ais constituted of both the branch groove portions214ain the first flow-path member210and the branch groove portion223ain the second flow-path member220and the second bifurcation flow path262bis constituted of both the branch groove portion214bin the first flow-path member210and the branch groove portion223bin the second flow-path member220. As a result, the cross-sectional areas of the second bifurcation flow paths262aand262bare widened, and thus pressure losses in the second bifurcation flow paths262aand262bare reduced. The second bifurcation flow path262amay be constituted of only the branch groove portion214ain the first flow-path member210and the second bifurcation flow path262bmay be constituted of only the branch groove portion214bin the first flow-path member210. Alternatively, the second bifurcation flow path262amay be constituted of only the branch groove portion223ain the second flow-path member220and the second bifurcation flow path262bmay be constituted of only the branch groove portion223bin the second flow-path member220. The branch groove portions214aand214bare formed in only the first flow-path member210on the Z2 side. Accordingly, in the area Q which is inclined in the Ya direction, and thus the Ya-direction width increases as the area Q extends from the Z1 side to the Z2 side, as described below, the degree of freedom in the arrangement of the second flow path242can be improved while preventing interference with the COF substrate98. Furthermore, the branch groove portions223aand223bare formed in only the second flow-path member220on the Z1 side. As a result, in the area P of which the width in the Ya direction increases as the area P extends from the Z2 side to the Z1 side, the degree of freedom in the arrangement of the second flow path242can be improved while preventing interference with the COF substrate98.

An end portion of the first bifurcation flow path261, which is the end portion on a side opposite to the first distribution flow path251, is connected to a first vertical flow path (which corresponds to a second flow path of the invention)271. Specifically, the first vertical flow path271is formed as a through-hole which passes through the third flow-path member230in the Z direction.

In this embodiment, vertical flow paths are respectively connected to the first bifurcation flow paths261a1to261a6and261b1to261b6. In other words, in total, twelve first vertical flow paths271a1to271a6and271b1to271b6are respectively connected to the first bifurcation flow paths.

Similarly, an end portion of the second bifurcation flow path262, which is the end portion on a side opposite to the second distribution flow path252, is connected to a second vertical flow path (which is the second flow path of the invention)272. Specifically, a through-hole224is provided in the second flow-path member220, in a state where the through-hole224passes through the second flow-path member220in the Z direction. A through-hole233is provided in the third flow-path member230, in a state where the through-hole233passes through the third flow-path member230in the Z direction. The through-hole224and the through-hole233communicate with each other, in such a manner that the second vertical flow path272is formed.

In this embodiment, in total, twelve second vertical flow paths272a1to272a6and272b1to272b6are respectively connected to second bifurcation flow paths262a1to262a6and262b1to262b6.

Hereinafter, a first vertical flow path271aindicates the first vertical flow paths271a1to271a6. A first vertical flow path271bindicates the first vertical flow paths271b1to271b6. The first vertical flow path271indicates all of the first vertical flow paths271aand the first vertical flow paths271b.

Similarly, a second vertical flow path272aindicates the second vertical flow paths272a1to272a6. A second vertical flow path272bindicates the second vertical flow paths272b1to272b6. The second vertical flow path272indicates all of the second vertical flow paths272aand the second vertical flow paths272b.

Furthermore, a vertical flow path270indicates all of the twenty-four vertical flow paths described above.

Reference letters and numerals corresponding to the first vertical flow paths271a2to271a5of the six first vertical flow paths271a1to271a6aligned in the Y direction are omitted in the accompanying drawings. However, it is assumed that the first vertical flow paths271a2to271a5are aligned in order from the Y1 side to the Y2 side. The first vertical flow paths271b1to271b6, the second vertical flow paths272a1to272a6, and the second vertical flow paths272b1to272b6have a similar configuration to that described above.

The vertical flow path270described above has the connection portion290which is an opening on the Z1 side of the third flow-path member230. The connection portion290communicates with the introduction path44provided in the head main body110. Details of this will be described below.

In this embodiment, the first vertical flow paths271a1to271a6respectively have first connection portions291a1to291a6which are openings on the Z1 side of the third flow-path member230. In addition, the first vertical flow paths271b1to271b6respectively have first connection portions291b1to291b6which are openings on the Z1 side of the third flow-path member230. Similarly, the second vertical flow paths272a1to272a6respectively have second connection portions292a1to291a6which are openings on the Z1 side of the third flow-path member230. In addition, the second vertical flow paths272b1to272b6respectively have second connection portions292b1to291b6which are openings on the Z1 side of the third flow-path member230.

The first connection portion291a1, the first connection portion291b1, the second connection portion292a1, and the second connection portion292b1are connected to one of the six head main bodies110. The first connection portions291a2to291a6, the first connection portions291b2to291b6, the second connection portions292a2to292a6, and the second connection portions292b2to292b6have a similar configuration to that described above. In other words, the first flow path241a, the first flow path241b, the second flow path242a, and the second flow path242bare connected to one head main body110.

Hereinafter, the first connection portion291aindicates the first connection portions291a1to291a6. The first connection portion291bindicates the first connection portions291b1to291b6. A first connection portion291indicates all of the first connection portions291aand the first connection portions291b.

Similarly, the second connection portion292aindicates the second connection portions292a1to292a6. The second connection portion292bindicates the second connection portion292b1to292b6. A second connection portion292indicates all of the second connection portions292aand the second connection portions292b.

Furthermore, a connection portion290indicates all of the twenty-four connection portions described above.

The flow-path member200according to this embodiment includes four flow paths240, in other words, the first flow path241a, the first flow path241b, a second flow path242a, and a second flow path242b, as described above. In each flow path240, a part extending from the introduction flow path280as an ink inlet port to an distribution flow path250constitutes one flow path and the distribution flow path250branches into bifurcation flow paths260. The bifurcation flow paths260are connected to a plurality of head main bodies110via both the vertical flow paths270and the connection portions290.

In this embodiment, a black ink Bk, a magenta ink M, a cyan ink C, and a yellow ink Y are used. The cyan ink C, the yellow ink Y, the black ink Bk, and the magenta ink M are respectively supplied from the liquid storage units (not illustrated) to the first flow path241a, the first flow path241b, the second flow path242a, and the second flow path242b. The color inks respectively flow through the first flow path241a, the first flow path241b, the second flow path242a, and the second flow path242b, and then the color inks are supplied to the head main bodies110.

Here, details of a connection portion between the bifurcation flow path260and the vertical flow path270will be described with reference toFIG. 17.

The bifurcation flow path260extends in a direction intersecting the vertical flow path270which extends in the vertical direction, as described above. In other words, the bifurcation flow path260of this embodiment extends in a direction perpendicular to the vertical direction. In a case where a portion in which the extended flow path of the bifurcation flow path260intersects the extended flow path of the vertical flow path270is set to the connection portion275, when the shape of a surface of the connection portion275, which is the surface on the upper side in the vertical direction, is formed as follows, in a plan view of a cross-sectional area including both the extension direction of the bifurcation flow path260and the extension direction of the vertical flow path270. A connection surface401connecting the surface of the bifurcation flow path260and the surface of the vertical flow path270is curved. The reason for this is that it is easy for air bubbles403to flow along the connection surface401on the upper side of the connection portion275in the vertical direction, and thus the air bubbles403is prevented from remaining in the upper side of the connection portion275in the vertical direction. Furthermore, the shape of the upper-side surface of the connection portion275in the vertical direction is not limited to a curved shape. The upper-side surface of the connection portion275may be constituted of, for example, an inclined surface or a plurality of connected inclined surfaces (in other words, the upper-side surface may be formed in a polygonal shape), as long as it can prevent the air bubbles403from remaining. The upper-side surface of the connection portion275may be constituted of a surface which intersects both the surface of the bifurcation flow path260and the surface of the vertical flow path270, at an angle greater than an angle402between an imaginary line extending in the extension direction of the bifurcation flow path260and an imaginary line extending in the extension direction of the vertical flow path270.

In the bifurcation flow path260, the intersection portion410is provided in the vicinity of the vertical flow path270. The intersection portion410is an area which extends from a start position411to an end position412, in the flowing direction of ink in the bifurcation flow path260. The intersection portion410of this embodiment includes an intersection surface415constituted of an inclined surface. Such an intersection surface415is provided in the intersection portion410, in such a manner that the cross-sectional area of the flow path is gradually reduced as the flow path extends to the downstream side, toward the connection portion275. Therefore, the flow velocity gradually increases, and thus flowing of air bubbles in the connection portion275is promoted. As a result, it is possible to prevent the air bubbles403from remaining.

When the intersection portion410is provided in the first bifurcation flow path portion261, the Z-direction depth of the branch groove portions232aand232bin the Z2-side surface of the third flow-path member230may be gradually reduced as the branch groove portions extend from a side in which the branch groove portions232aand232brespectively communicate with the distribution groove portions231aand231bto a side in which the openings of the through-hole portions of the first vertical flow paths271are provided. Specifically, on a side in which the branch groove portions232aand232brespectively communicate with the distribution groove portions231aand231b, the Z-direction depth of the branch groove portions232aand the232bon the Z2-side surface of the third flow-path member230may be set to the same value as that of the distribution groove portions231aand231b. On a side in which the openings of the through-hole portions of the first vertical flow paths271are provided, the depth of the branch groove portions232aand232bmay be set to the value smaller than that of the distribution groove portions231aand231b. When the intersection portion410is provided in the second bifurcation flow path262, a similar configuration to that described above may be applied to second flow-path member220, instead of the third flow-path member230. The intersection portion410is provided on, particularly, a lower side in the vertical direction, in such a manner that flowing of ink to the connection surface401is promoted on the upper side of the connection portion275in the vertical direction. Accordingly, the air bubbles403flow to the vertical flow path270, along the connection surface401of the connection portion275, which is located on the upper side in the vertical direction. As a result, it is possible to prevent the air bubbles403from remaining.

Furthermore, it is preferable that the cross-sectional area of the vertical flow path270is smaller than that of the bifurcation flow path260. In this case, the flow velocity of ink the vertical flow path270increases, and thus it is possible to effectively flow the air bubbles403to the lower side in the vertical direction. In addition, it is preferable that the cross-sectional area of the vertical flow path270is smaller than the cross-sectional area of a part of the bifurcation flow path260, which is the portion extending from the intersection portion410to the connection portion275. In this case, the flow velocity of ink the vertical flow path270increases, and thus it is possible to effectively flow the air bubbles403to the lower side in the vertical direction.

For example, the inclination angle or the length of the inclined surface of the intersection surface415is appropriately set, in such a manner that it is possible to increase the flow velocity and, further, it is possible to adjust the degree of reduction in pressure loss and discharge properties of the air bubbles403.

The configuration of the intersection surface415is not limited to the configuration in which the intersection surface415is constituted of an inclined surface. The intersection surface415may be an intersection surface415A which is constituted of a stepped surface, as illustrated inFIG. 18.

Furthermore, any configuration can be applied to the intersection portion410, as long as it can change the cross-sectional area of the flow-path. Thus, the cross-sectional area of the intersection portion410may change by changing the width (which is the size of the flow path in a direction perpendicular to the paper ofFIG. 17) of the flow path.

In other words, it is preferable that the intersection portion410(in other words, the intersection surface415) is provided on the lower side of the bifurcation flow path260in the vertical direction. However, the intersection surface415may be provided on the upper side or a side surface of the bifurcation flow path260. However, when the intersection surface415is provided on the lower side of the bifurcation flow path260, as in the case of this embodiment, the flow passing through the intersection portion410is directed to the connection surface401. Thus, even when the air bubbles403are located in the vicinity of the connection surface401, the air bubbles403can be reliably discharged by the flow passing the intersection portion410. Furthermore, it is not necessary to increase/decrease the width of the flow path in a direction perpendicular to the paper ofFIG. 17, in order to increase/decrease the cross-sectional area. Thus, when a plurality of flow paths are aligned in the direction perpendicular to the paper ofFIG. 17, there is an advantage in that a gap between adjacent flow paths can be reduced. In other words, in the first bifurcation flow path portions261a1to261a6, a Y-direction gap between adjacent flow paths can be reduced. Similarly, a Y-direction gap between adjacent flow paths of the other bifurcation flow paths260can be reduced.

Furthermore, since such an intersection portion410is provided, it is possible to reduce the pressure loss in the flow path extending to the intersection portion410, as small as possible. As a result, it is possible to reduce the entirety of pressure losses. In other words, In the distribution flow path250and the bifurcation flow path260, the pressure losses in the flow paths extending to the intersection portions410are reduced as small as possible and the air-bubble discharge properties in the connection portions275are improved by increasing the flow velocity in the intersection portions410. As a result, both a reduction in pressure loss and favorable air-bubble discharge properties are obtained in the entirety of the flow paths.

In this embodiment, six groups of the bifurcation flow paths260and the vertical flow paths270are provided in one flow path240, as described above. The distances from the introduction flow path280to the vertical flow paths270of the respective groups are different from each other.FIG. 19illustrates a schematic perspective view of both the first flow path241aand the second flow path242aof the flow path240.

The respective groups of the first bifurcation flow path portions261a1to261a6and the first vertical flow paths271a1to271a6communicate with the first distribution flow path251acommunicating with the first introduction flow path281a, as illustrated inFIG. 19. Furthermore, the distances from the first introduction flow path281ato the respective first vertical flow paths271a1to271a6of the groups are different from each other. Furthermore, the respective groups of the second bifurcation flow paths262a1to262a6and the second vertical flow paths272a1to272a6communicate with the second distribution flow path252acommunicating with the second introduction flow path282a. In addition, the distances from the second introduction flow path282ato the respective second vertical flow paths272a1to272a6of the groups are different from each other.

In the bifurcation flow paths260having a configuration in which the distances from the introduction flow path280to the respective vertical flow paths270of the groups are different from each other, variation in pressure losses occur in portions extending to the intersection portions410. However, the degree of intersection between the intersection surface415and the start position411and/or the end position412of the intersection portion410changes, in such a manner that the air-bubble discharge properties and the degree of reduction in the pressure loss in the intersection portion410can change. As a result, it is possible to reduce variation in the pressure losses in the bifurcation flow paths260.

In a plurality of bifurcation flow paths260having a configuration in which, for example, the distances from the introduction flow path280to the respective vertical flow paths270are different from each other, the amount of the pressure loss in the distant bifurcation flow path260is greater than that of the close bifurcation flow path260, as illustrated inFIGS. 20A and 20B. In this case, to reduce variation in the pressure losses in the bifurcation flow paths260, the intersection portions410may be provided in the distant bifurcation flow path260and the close bifurcation flow path260, in a state where a distant L1(seeFIG. 20A) from the start position411of the intersection portion410of the distant bifurcation flow path260to the vertical flow path270is set to be smaller than a distant L2(seeFIG. 20B) from the start position411of the intersection portion410of the close bifurcation flow path260to the vertical flow path270. In other words, the intersection portions410are provided in the bifurcation flow paths260, in a state where the relationship of L1<L2is satisfied.

Alternatively, the intersection portions410may be provided in the distant bifurcation flow path260and the close bifurcation flow path260, in a state where a distant L3(seeFIG. 20A) from the end position412of the intersection portion410of the distant bifurcation flow path260to the vertical flow path270is set to be smaller than a distant L4(seeFIG. 20B) from the end position412of the intersection portion410of the close bifurcation flow path260to the vertical flow path270. In other words, the intersection portions410are provided in the bifurcation flow paths260, in a state where the relationship of L3<L4is satisfied.

Meanwhile, when it is assumed that the flow rates in the respective vertical flow paths270are set to the same value, as illustrated inFIG. 19, the flow rate and the flow velocity in the distribution flow path250change in accordance with the number of bifurcation portions. Accordingly, the cross-sectional area of the distribution flow path250is gradually reduced in accordance with the number of bifurcation points, in such a manner that variation in the flow velocities in the bifurcation flow paths260of the respective groups, which are connected to the distribution flow path250, can be reduced.

In other words, the cross-sectional areas of the respective bifurcation flow paths are gradually reduced, in such a manner that the variation in flow velocities can be reduced. Specifically, the cross-sectional area of a part of the distribution flow path, which is the portion from the introduction flow path280to a first bifurcation flow path is set to the maximum value and the cross-sectional area of a part of the of the distribution flow path, which is the portion to a next bifurcation flow path is set to a value smaller than the maximum value.

The second bifurcation flow path262is formed in the boundary surface between the first flow-path member210and the second flow-path member220, as illustrated inFIGS. 20A and 20B. However, it is preferable that the end position412of the intersection portion410is formed by only the second flow-path member220, without using the first flow-path member210and other members. In other words, when an intersection portion410B of which the end position412is located on the side of the first flow-path member210is provided, as illustrated inFIG. 21, the intersection portion410B cannot be formed by only the branch groove portions223a,223b,232a, and232bin the first flow-path member210. Thus, it is necessary to provide a through-hole which passes through the first flow-path member210, in a direction perpendicular to the Z direction. As a result, it is difficult to perform processing. Although not illustrated, a configuration in which an intersection portion is formed by the first flow-path member210and other members is unpreferable in terms of processing. The reason for this is an increase in the number of parts. This situation is shared by the first bifurcation flow path portion261which is formed in the boundary surface between the second flow-path member220and the third flow-path member230.

It is more preferable that an intersection portion410C of the second bifurcation flow path262is formed by only the first flow-path member210, as illustrated inFIG. 22, and the end position412of the intersection portion410C is located further on the side of the second flow-path member220than the boundary surface between the first flow-path member210and the second flow-path member220. In other words, a part of the intersection portion, which is a portion deciding the cross-sectional area of the flow path, may be located further on the side of the second flow-path member220than the boundary surface between the first flow-path member210and the second flow-path member220. When the end position412is located in the boundary surface between the first flow-path member210and the second flow-path member220, it is difficult to manage an adhesion surface (in other words, it is difficult to manage surface roughness and a reference surface). When the configuration described above is not applied to the invention, the following problem is caused. When an adhesion surface is processed with relatively higher precision, compared to a flow path surface, the adhesion surface and the flow path surface are located, in the same plane, close to each other. As a result, management of both surfaces is complicated, and thus there is a problem in that it is difficult to perform processing. Accordingly, it is preferable that the intersection portion410C of the second bifurcation flow path262is formed by only the first flow-path member210, as illustrated inFIG. 22. This situation is shared by the first bifurcation flow path portion261which is formed in the boundary surface between the second flow-path member220and the third flow-path member230.

In this case, the bifurcation flow path260is formed in both a portion between the first flow-path member210and the second flow-path member220and a portion between the second flow-path member220and the third flow-path member230, and thus the bifurcation flow path260is formed in a two-stage shape, as described above. Similarly, the distribution flow path250is formed in a two-stage shape.

FIGS. 23A and 23Billustrate the schematic configuration of the distribution flow path250and the bifurcation flow path260. In a case where a flow path A1of a first stage and a flow path A2of a second stage are projected in the vertical direction, when the projection images thereof do not overlap, as illustrated inFIG. 23A, it is possible to reduce the vertical-direction (in other words, the thickness-direction) size of the member. When the projection images overlap each other, as illustrated inFIG. 23B, it is possible to reduce the X-direction/Y-direction (which is the width direction of the flow path) size of the member. Either configuration may be applied to the invention. Both the flow path A1of the first stage and the flow path A2of the second stage may be the distribution flow paths250or may be the bifurcation flow paths260.

In the four flow paths240described above, in the flow paths A1of the first stage and the flow paths A2of the second stage, the distances from the inlet ports of the introduction flow paths280to the distribution flow paths250are different from each other. Thus, variation in the pressure losses occurs in the flow paths. Accordingly, it is preferable that, in a portion between the flow path A1of the first stage and the flow path A2of the second stage, the diameter of the introduction flow path280and the cross-sectional area of a part of the distribution flow path250, which is the portion extending to the intersection portion410, change, in order to reduce the variation in the pressure losses. Specifically, the cross-sectional area of a part of the first flow path241, which is the portion extending to the intersection portion410of the first flow path portion251may be set to be greater than the cross-sectional area of a part of the second flow path242, which is the portion extending to the intersection portion410of the second distribution flow path252. Furthermore, it is preferable that, to allow air bubbles to flow downward, the size of the introduction flow path280is reduced as much as possible. The cross-sectional area of the flow path is slightly increased as the length of the introduction flow path280increases, in such a manner that variation in the pressure loss can be reduced.

In this case, the opening portion201is provided in the flow-path member200. The COF substrate98provided in the head main body110is inserted through the opening portion201. In this embodiment, the first opening portion215is provided in the first flow-path member210. The first opening portion215is inclined with respect to the Z direction and passes through the first flow-path member210. The second opening portion225is provided in the second flow-path member220, the second opening portion225is inclined with respect to the Z direction and passes through the second flow-path member220. The third opening portion235is provided in the third flow-path member230. The third opening portion235is inclined with respect to the Z direction and passes through the third flow-path member230.

The first opening portion215, the second opening portion225, and the third opening portion235communicate with one another, in such a manner that one opening portion201is formed. The opening portion201has an opening shape extending in the Xa direction. Six opening portions201are aligned in the Y direction.

In this case, the COF substrate98according to this embodiment includes a lower end portion98cand an upper end portion98d, as illustrated inFIG. 16. The lower end portion98cis one end portion of the COF substrate98, which is close, in the Z direction, to the head main body110. The upper end portion98dis the other end portion of the COF substrate98, which is far away, in the Z direction, from the head main body110. The width of the upper end portion98din the Xa direction is smaller than the width of the lower end portion98cin the Xa direction.

In this embodiment, a part of the COF substrate98, which is inserted through the first opening portion215, and a part of the COF substrate98, which is inserted through the third opening portion235, have a rectangular shape of which the Xa-direction width is constant. A part of the COF substrate98, which is inserted through the second opening portion225, has a trapezoidal shape of which the Xa-direction width is reduced as the part of the COF substrate98extends from the Z1 side to the Z2 side.

Meanwhile, the opening portion201of the flow-path member200has a first opening236(in other words, the Z1-side opening of the third opening portion235) and a second opening216(in other words, the Z2-side opening of the first opening portion215). In the Z direction perpendicular to the liquid ejection surface20a, the first opening236is close to the head main body110and the second opening216is far away from the head main body110.

The size of the second opening216in the Xa direction is smaller than the size of the first opening236in the Xa direction. In other words, the width of the opening portion201in the Xa direction is reduced as the opening portion201extends from the Z1 side to the Z2 side in the Z direction. Specifically, the opening portion201has a shape allowing the COF substrate98to be accommodated therein. The width of the opening portion201in the Xa direction is slightly greater than the width of the COF substrate98in the Xa direction.

Other Embodiments

Hereinbefore, the embodiments of the invention are described. However, the basic configuration of the invention is not limited thereto.

In the recording head100according to Embodiment 1, the first flow path241and the second flow path242are provided and the first distribution flow path251and the second distribution flow path252are located at different positions in the Z direction. However, the configuration is not limited thereto. A recording head may include a flow-path member in which flow paths parallel to the liquid ejection surface20aare provided in, for example, only the same plane. According to the embodiment described above, a recording head may have a configuration in which only second flow path is provided in a flow-path member including the first flow-path member210and the second flow-path member220. In the case of the recording head in which either the first flow path241or the second flow path242is not provided, as described above, the Z-direction size of the recording head100can be reduced.

In the recording head100according to Embodiment 1, the introduction paths44c,44d,44a, and44bare connected to the first flow path241a, the first flow path241b, the second flow path242a, and the second flow path242b. However, the configuration is not limited thereto. The introduction paths44cand44b, for example, may be connected to the first flow path241aand the first flow path241band the introduction paths44aand44dmay be connected to the second flow paths242aand242b. In this case, a recording head may have only the second flow path without the first flow path. It is possible to provide an optimal flow path having the optimal configuration in relation to, for example, the arrangement of the head main bodies110.

The second flow path242is formed by causing the first flow-path member210and the second flow-path member220to adhere to each other and the first flow path241is formed by causing the second flow-path member220and the third flow-path member230to adhere to each other. However, the method of forming the first flow path241and the second flow path242is not limited thereto. The first flow path241and the second flow path242may be integrally formed, without causing two or more flow-path member to adhere to each other, by a lamination forming method allowing three-dimensional forming. Alternatively, each flow-path member may be formed by three-dimensional forming, molding (for example, injection molding), cutting, pressing.

The flow-path member200has, as the first flow path241, two flow paths which are the first flow path241aand the first flow path241b. However, the number of first flow paths is not limited thereto. One first flow path may be provided or three or more first flow paths may be provided. The second flow path242has a similar configuration to that described above.

The first distribution flow path251abranches into the six first bifurcation flow paths261a. However, the configuration is not limited thereto. The first distribution flow path251amay be connected to one head main body110, without being branched. The number of branched-off flow paths is not limited to six and may be two or more. The first distribution flow path251b, the second distribution flow path252a, and the second distribution flow path252bhave a similar configuration to that described above.

The cross-sectional area of the distribution flow path250is reduced in accordance with the number of distribution points. However, the cross-sectional area of the distribution flow path250may not be reduced and be constant. Furthermore, in the flow path A1of the first stage and the flow path A2of the second stage, the diameters of the introduction flow paths280are set to be different from each other and, further, the cross-sectional areas of parts of the distribution flow paths250, which are the portions extending to the intersection portions410, are set to be different from each other. However, in the flow path A1of the first stage and the flow path A2of the second stage, the cross-sectional areas may not be different from each other and may be the same.

In either configuration, it is possible to more effectively flow the air bubbles403to the lower side in the vertical direction, as long as the cross-sectional area of the vertical flow path270is smaller than that of the bifurcation flow path260.

The first distribution flow path251ais a flow path through which ink horizontally flows in a portion between the second flow-path member220and the third flow-path member230. However, the configuration is not limited thereto. In other words, the first distribution flow path251amay be a flow path inclined with respect to a Z plane. The first distribution flow path251b, the second distribution flow path252a, and the second distribution flow path252bhave a similar configuration.

Furthermore, the first vertical flow path271ais perpendicular to the liquid ejection surface20a. However, the configuration is not limited thereto. In other words, the first vertical flow path271amay be inclined with respect to the liquid ejection surface20a. The first vertical flow path271b, the second vertical flow path272a, and the second vertical flow path272bhave a similar configuration.

It is not necessary to set the Xa-direction width of the second opening216of the opening portion201in the flow-path member200to be smaller than that of the first opening236. The second opening216and the first opening236may be openings of which the Xa-direction widths are substantially the same and which allow the rectangular-shaped COF substrate98to be accommodated therein. On the contrary, the Xa-direction width of the second opening216may be greater than that of the first opening236.

The COF substrate98is provided as a flexible wiring substrate. However, a flexible print substrate (FPC) may be used as the COF substrate98.

In Embodiment 1, the head main bodies110are aligned in the Y direction and the recording head100is constituted of the plurality of head main bodies110. However, the recording head100may be constituted of one head main body110. Furthermore, the number of recording heads100in the head unit101is not particularly limited. The number of recording heads100may be two or more. Alternatively, one single recording head100may be mounted in the ink jet type recording apparatus1.

In Embodiment 1, the holding member120and the flow-path member200are fixed using, for example, an adhesive. However, the holding member120and the flow-path member200may be integrally formed. In other words, both the hold portion121and the leg portion122may be provided on the Z1 side of the flow-path member200. Accordingly, the holding member120is not stacked in the Z direction, the Z-direction size of the flow-path member200can be reduced. Furthermore, since the hold portion121is provided in the flow-path member200, the size of the flow-path member200in both the X direction and in the Y direction can be reduced because it is necessary for the flow-path member200to accommodate only a plurality of head main bodies110and it is not necessary for the flow-path member200to accommodate the relay substrate140. Furthermore, a plurality of members are integrally formed, and thus the number of parts can be reduced. When the flow-path member200is constituted of the first flow-path member210, the second flow-path member220, and the third flow-path member230, both the hold portion121and the leg portion122may be provided on the Z1 side of the third flow-path member230.

The ink jet type recording apparatus1described above is a so-called line type recording apparatus in which the head unit101is fixed and only the recording sheet S is transported, in such a manner that printing is performed. However, the configuration is not limited thereto. The invention can be applied to a so-called serial type recording apparatus in which the head unit101and one or a plurality of recording heads100are mounted on a carriage, the head unit101or the recording head100move in a main scanning direction intersecting the transporting direction of the recording sheet S, and the recording sheet S is transported, in such a manner that printing is performed.

The invention is intended to be applied to a general liquid ejecting head unit. The invention can be applied to a liquid ejecting head unit which includes a recording head of, for example, an ink jet type recording head of various types used for an image recording apparatus, such as a printer, a coloring material ejecting head used to manufacture a color filter for a liquid crystal display or the like, an electrode material ejecting head used to form an electrode for an organic EL display, a field emission display (FED) or the like, or a bio-organic material ejecting head used to manufacture a biochip.

A wiring substrate of the invention is not intended to be applied to only a liquid ejecting head and can be applied to, for example, a certain electronic circuit.