JP2011093266A - Liquid ejection head and liquid ejection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejection head which adequately discharges bubbles staying in a reservoir to outside through a nozzle, and to provide a liquid ejection device. <P>SOLUTION: This liquid ejection head 11 includes a fluid channel forming substrate 24 having a plurality of pressure generating chambers 23 communicating with the nozzles 21 and the reservoir 27, and pressure generating means 25 for generating pressure changes in the respective pressure generating chambers 23. The pressure generating chambers 23 and the reservoir 27 are connected with liquid supply holes 28 formed on the fluid channel forming substrate 24. The reservoir 27 has a width gradual reduction part 50 constituted so that the width of the reservoir 27 in a juxtaposing direction of the liquid supply holes 28 at an end on a liquid supply hole 28 side is gradually reduced toward a pressure generating chamber side. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid ejecting head and a liquid ejecting apparatus that eject droplets from nozzles.

A typical example of a liquid ejecting head is an ink jet recording head that ejects ink droplets from a nozzle by pressurizing ink in a pressure generating chamber communicating with the nozzle by an actuator. Various flow path structures of the ink jet recording head have been proposed, but in general, a plurality of pressure generation chambers are connected to a reservoir by ink supply paths,
Ink is supplied from the reservoir to each pressure generating chamber. In particular,
A pressure generating chamber is formed on one surface side of the flow path forming substrate, and a reservoir is formed by penetrating the flow path forming substrate in the thickness direction. Some are connected by an ink supply port provided at the center in the vertical direction (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 7-76087

In the ink jet recording head having the flow path structure as described above, since bubbles are not ejected from the nozzles due to bubbles accumulated in the reservoir, the bubbles in the flow path are periodically discharged to the outside. There is a need to. In order to discharge the bubbles in the flow path to the outside,
For example, a suction operation is performed in which air bubbles accumulated in the reservoir are discharged from the nozzle together with ink by sucking the flow path from the nozzle at a predetermined timing. At this time, the bubbles in the reservoir are more easily drawn into the ink supply hole as they are in close contact with the opening of the ink supply hole (ink supply port), and are preferably discharged to the outside from the nozzle.

However, in the flow path structure as described above, for example, bubbles are stagnated at the corners or the like in the reservoir and do not sufficiently adhere to the openings of the ink supply holes, and the bubbles are drawn into the ink supply holes to cause nozzles. There is a possibility that it cannot be discharged well from the outside.

Such a problem exists not only in an ink jet recording head that ejects ink droplets from nozzles, but also in a liquid ejecting head that ejects other droplets.

SUMMARY An advantage of some aspects of the invention is that it provides a liquid ejecting head and a liquid ejecting apparatus that are capable of satisfactorily discharging bubbles accumulated in a reservoir from a nozzle to the outside.

The present invention for solving the above-mentioned problems is a flow path forming substrate in which a plurality of pressure generation chambers communicating with nozzles for ejecting droplets and a reservoir for storing liquid supplied to the plurality of pressure generation chambers are formed, Pressure generating means for generating a pressure change for ejecting droplets from the nozzle into the pressure generating chamber, wherein the pressure generating chamber and the reservoir are the flow path forming substrate. The reservoir is connected to the end of the liquid supply hole at the end of the liquid supply hole, and the width of the reservoir in the juxtaposition direction of the liquid supply hole gradually decreases toward the pressure generation chamber. The liquid ejecting head has a gradually decreasing width portion. For example, it is preferable that the width gradually decreasing portion has a width of the reservoir gradually decreasing toward the central portion of the flow path forming substrate in the direction in which the liquid supply holes are arranged side by side. In other words, it is preferable that the opening of each liquid supply hole is located closer to the pressure generating chamber as it is closer to the center of the flow path forming substrate.

In the present invention, the bubbles in the reservoir are gathered in the gradually decreasing width portion during the suction operation or the like, so that the bubbles are easily drawn into the liquid supply hole. Therefore, it is possible to discharge the air bubbles from the nozzles to the outside.

Moreover, it is preferable that the end surface of the reservoir constituting the gradually decreasing width portion and opening the liquid supply hole is a spherical surface. Thereby, the contact area with the end surface of the bubble reservoir (gradually smaller width portion) is increased, and the bubbles are more easily drawn into the liquid supply hole by the suction operation.

According to another aspect of the invention, there is provided a liquid ejecting apparatus including such a liquid ejecting head. According to the present invention, it is possible to maintain the ejection characteristics of the droplets well over a long period of time, and it is possible to realize a liquid ejection apparatus having excellent durability.

1 is a schematic perspective view of a recording apparatus according to Embodiment 1. FIG. FIG. 3 is a cross-sectional view illustrating the recording head according to the first embodiment. FIG. 3 is a cross-sectional view illustrating a flow path structure of the recording head according to the first embodiment. It is a figure explaining the state of the bubble at the time of suction operation in the recording head of the present invention. 6 is a cross-sectional view illustrating a modification of the flow path structure of the recording head according to Embodiment 1. FIG. 6 is a cross-sectional view illustrating a modification of the flow path structure of the recording head according to Embodiment 1. FIG. 6 is a cross-sectional view illustrating a modification of the flow path structure of the recording head according to Embodiment 1. FIG. FIG. 3 is a longitudinal sectional view illustrating a flow path structure of the recording head according to the first embodiment. 3 is a cross-sectional view illustrating a configuration of a flow path forming substrate according to Embodiment 1. FIG.

Hereinafter, the present invention will be described in detail based on embodiments.
(Embodiment 1)
FIG. 1 is a schematic perspective view of an ink jet recording apparatus which is an example of a liquid ejecting apparatus according to Embodiment 1 of the invention. As shown in FIG. 1, the ink jet recording apparatus 10 of the present embodiment has an ink jet recording head (hereinafter simply referred to as “recording head”) 11 for ejecting ink droplets from nozzles fixed to a carriage 12. 11, ink cartridges 13 that are liquid storage units in which a plurality of different color inks such as black, cyan, magenta, and yellow are stored are detachably fixed.

The carriage 12 on which the recording head 11 is mounted is provided on a carriage shaft 15 attached to the apparatus main body 14 so as to be movable in the axial direction. Then, the driving force of the driving motor 16 is transmitted to the carriage 12 via a plurality of gears and a timing belt 17 (not shown), so that the carriage 12 is moved along the carriage shaft 15. On the other hand, the apparatus main body 14 is provided with a platen 18 along the carriage shaft 15, so that a recording medium S such as paper fed by a paper feeding device (not shown) is conveyed on the platen 18. ing.

A suction means 19 is provided in a non-printing area on the side of the platen 18 that is an end of the carriage 12 in the moving direction. The suction means 19 is, for example, a cap member 19a that covers the nozzles of the recording head 11, and the cap member 19a connected to the cap member 19a via a tube 19b.
For example, it comprises a suction device 19c such as a vacuum pump.

The suction means 19 having such a configuration performs a so-called suction operation at a predetermined timing. Specifically, the suction unit 19 brings the cap member 19a into contact with the nozzle opening surface of the recording head 11, and sucks the inside of the cap member 19a by the suction device 19c to make negative pressure. Thereby, the inside of the ink flow path of the recording head 11 is sucked from the nozzle, and the bubbles are discharged to the outside together with the ink.

In the recording head according to the present invention, as described below, when such a suction operation is executed, the bubbles in the reservoir constituting the ink flow path can be discharged to the outside more satisfactorily.

The configuration of the recording head of the present invention will be described below. FIG. 2 is a cross-sectional view illustrating the recording head according to the first embodiment. As shown in FIG. 2, the recording head 11 includes a nozzle plate 22 having a plurality of nozzles 21 for ejecting ink droplets, and a plurality of nozzle plates 22 joined to one side and communicating with the nozzles 21. A flow path forming substrate 24 in which the pressure generating chamber 23 is formed.
And an actuator 25 as pressure generating means provided on the surface of the flow path forming substrate 24 opposite to the nozzle plate 22.

In the present embodiment, in the flow path forming substrate 24, the nozzle communication hole 26, together with the pressure generating chamber 23,
A reservoir 27 and an ink supply hole (liquid supply hole) 28 are formed. Pressure generation chamber 23
Are provided on the surface layer portion on one surface side of the flow path forming substrate 24, and are partitioned by the partition walls 29 and arranged in parallel in the width direction.

The nozzle communication hole 26 is provided so as to penetrate the flow path forming substrate 24 in the thickness direction, and one end portion of each pressure generation chamber 23 and the nozzle 21 communicate with each other through the nozzle communication hole 26. The reservoir 27 is a space in which ink to be supplied to each pressure generating chamber 23 is temporarily stored, and the flow path forming substrate 24 is disposed in the thickness direction in a region outside the other end of the pressure generating chamber 23. It is provided through. The reservoir 27 and each pressure generating chamber 23 are connected to each other by an ink supply hole 28.

As described above, the pressure generation chamber 23 is provided in the surface layer portion of the flow path forming substrate 24, whereas the ink supply hole 28 is provided in the center portion in the thickness direction of the flow path forming substrate 24. That is, the ink supply hole 28 is formed so as to penetrate the portion between the pressure generation chamber 23 and the reservoir 27 of the flow path forming substrate 24 along the longitudinal direction of the pressure generation chamber 23. It communicates near the bottom.

The ink supply hole 28 plays a role of maintaining a constant flow path resistance of ink flowing from the reservoir 27 to the pressure generation chamber 23, and is formed with a narrower width than the pressure generation chamber 23 in this embodiment. .

As will be described in detail later, the width of the reservoir 27 in the direction in which the ink supply holes 28 are juxtaposed is gradually reduced toward the pressure generating chamber 23 at the end of the reservoir 27 on the ink supply hole 28 side. 50 is provided, and the effect of discharging the bubbles during the suction operation is enhanced by the gradually decreasing width portion 50.

A vibration plate 30 is joined to the surface of the flow path forming substrate 24 opposite to the nozzle plate 22, that is, the opening surface side of the pressure generation chamber 23, and one surface of each pressure generation chamber 23 is the vibration plate. 3
0 is configured. On the vibration plate 30, a piezoelectric element 31 for generating pressure in each pressure generating chamber 23 is provided. In other words, in the present embodiment, the vibration plate 30 and the piezoelectric element 31 provided on the vibration plate 30 constitute an actuator 25 that is a pressure generating means.

In the present embodiment, the vibration plate 30 includes a sheet member 32 and a support plate 33, and includes an island portion 34 that is configured by the support plate 33 and with which the tip of the piezoelectric element 31 contacts.

The configuration of the piezoelectric element 31 is not particularly limited. In the present embodiment, the piezoelectric element 31 is configured by stacking the piezoelectric material 35 and the electrode forming materials 36 and 37 alternately sandwiched in the vertical direction. The piezoelectric element 31 has an active region that contributes to vibration and an inactive region that does not contribute to vibration. The piezoelectric element 31 is fixed in a state where the tip of the active region is in contact with the island portion 34 of the diaphragm 30, and An inactive region that does not contribute is fixed to the fixed substrate 38.

On the vibration plate 30, a head case 40 having a piezoelectric element holding portion 39 capable of sealing the space while securing a space that does not hinder the movement of the piezoelectric element 31 is fixed.
The fixed substrate 38 to which the piezoelectric element 31 is fixed is fixed to the head case 40 on the surface opposite to the piezoelectric element 31.

In such a recording head 11, the actuator (the vibration plate 30 and the piezoelectric element 31) 2
The volume of each pressure generating chamber 23 is changed by the deformation of No. 5, and ink droplets are ejected from a predetermined nozzle 21. Specifically, when ink is supplied to the reservoir 27 from an ink cartridge (not shown), the ink is distributed to each pressure generating chamber 23 via the ink supply hole 28. Actually, the diaphragm 30 is deformed together with the piezoelectric element 31 by contracting the piezoelectric element 31 by applying a voltage to the piezoelectric element 31, and the volume of the pressure generating chamber 23 is expanded, and each pressure generating chamber 23 is expanded. Ink is drawn. After the recording head 11 is filled with ink up to the nozzle 21, the voltage applied to the piezoelectric element 31 is released in accordance with a recording signal from a drive circuit (not shown). Thereby, the piezoelectric element 31 is expanded to return to the original state, and the displacement of the diaphragm 30 also returns to the original state. As a result, the pressure generating chamber 23 contracts to increase the internal pressure, and an ink droplet is ejected from the nozzle 21.

Here, in the recording apparatus 10 having such a recording head 11, the suction operation is executed at a predetermined timing as described above. The recording head 11 according to the present invention includes a reservoir 27.
Since the gradually decreasing width portion 50 is provided at the end of the ink supply hole 28 side, bubbles in the ink flow path such as the reservoir 27 can be discharged well from the nozzle 21 to the outside during this suction operation. it can. Hereinafter, the width gradually decreasing portion 50 will be described in detail.

FIG. 3 is a cross-sectional view showing the flow path structure of the recording head, particularly the structure of the gradually decreasing width of the reservoir. As shown in FIG. 3, at the end of the reservoir 27 on the ink supply hole 28 side, the width gradually decreasing portion where the width of the reservoir 27 in the direction in which the ink supply holes 28 are arranged gradually decreases toward the pressure generating chamber 23 side. 50 is provided. Specifically, the end surface of the reservoir 27 on the pressure generation chamber 23 side is
As indicated by a two-dot chain line in the figure, the pressure generating chamber 23 side is a curved surface that is convex. In particular, it is preferable that the end surface of the reservoir 27 constituting the gradually decreasing width portion 50 is a spherical surface. In the gradually decreasing width portion 50, the width of the reservoir 27 in the direction in which the ink supply holes 28 are arranged is gradually decreased toward the central portion of the flow path forming substrate 24. That is, the ink supply hole (gradually small portion) 28 located on the center side of the flow path forming substrate 24 is configured such that the opening is located on the pressure generation chamber 23 side.

In such a configuration, during the suction operation, as shown in FIG.
0 gathers at the center of the flow path forming substrate 24 in the direction in which the ink supply holes 28 are arranged side by side, so that the opening of the ink supply hole 28 is substantially blocked by the bubbles 100, and the bubbles 1
00 is easily drawn into the ink supply hole 28. In addition, since the width gradually decreasing portion 50 is provided, even when the bubble becomes very large, the contact area with the end face of the reservoir 27 becomes relatively large, so that the bubble is drawn into the ink supply hole 28. It becomes easy. Therefore, the bubbles can be discharged from the nozzle 21 to the outside more satisfactorily.

If the gradually decreasing width portion 50 is provided in the reservoir 27 as described above, the length of each ink supply hole 28 is not constant, and the flow resistance varies. For this reason, for example,
It is necessary to keep the flow path resistance of each ink supply hole 28 constant by adjusting the width of each ink supply hole 28 or the like. Alternatively, for example, as shown in FIG.
The positions of the pressure generating chambers 23 and the nozzles 21 may be changed while keeping the length of the ink supply holes 28 constant. In the case of this configuration, it is possible to maintain good print quality by adjusting the timing for driving the piezoelectric element by control.

In the present embodiment, an example in which the end surface of the reservoir 27 constituting the gradually decreasing width portion 50 is a curved surface has been described. Of course, the end surface of the reservoir 27 constituting the gradually decreasing width portion 50 is, for example, FIG. It may be a flat surface as indicated by a two-dot chain line. Further, the width gradually decreasing portion 50 in which the width of the reservoir 27 gradually decreases toward the center portion of the flow path forming substrate 24 is illustrated.
For example, as shown in FIG. 7, the flow path forming substrate 24 in the direction in which the ink supply holes 28 are arranged side by side.
The width of the reservoir 27 may be gradually reduced toward the one end portion. In any case, the bubbles in the reservoir 27 gather at one place, so that the bubbles can be easily discharged to the outside.

Further, in the present embodiment, a gradually decreasing portion 60 is provided in the opening of the ink supply hole 28 on the reservoir 27 side (see FIG. 2), and this gradually decreasing portion 60 further enhances the bubble discharging effect during the suction operation. It has been. Specifically, as shown in FIG. 8, the ink supply hole 28 has a gradually decreasing portion in which the inner diameter in the thickness direction of the flow path forming substrate 24 gradually decreases toward the pressure generating chamber 23 at the opening on the reservoir 27 side. 60. That is, the gradually decreasing portion 60 is a tapered surface in which both end surfaces (inner surfaces) 61 in the thickness direction of the flow path forming substrate 24 are inclined with respect to the surface of the flow path forming substrate 24. In the present embodiment, both end surfaces (inner surfaces) 62 of the gradually decreasing portion 60 in the surface direction of the flow path forming substrate 24 (the direction in which the pressure generating chambers 23 are arranged) are also tapered surfaces (see FIG. 3). Of course, both end surfaces 62 of the gradually decreasing portion 60 in the surface direction of the flow path forming substrate 24 are not necessarily tapered surfaces, and even if the width of the gradually decreasing portion 60 is constant in the longitudinal direction of the pressure generating chamber 23. Good.

In this embodiment, the flow path forming substrate 24 is formed by bonding two substrates, a first flow path forming substrate 24A and a second flow path forming substrate 24B, as shown in FIG. ing. The ink supply hole 28 (including the gradually decreasing portion 60) is, for example, the first flow path forming substrate 2.
4A and groove portions 41 and 4 provided on the joint surface with the other of the second flow path forming substrate 24B, respectively.
2.

As described above, since the gradually decreasing portion 60 is provided in the opening portion of the ink supply hole 28 on the reservoir 27 side, bubbles in the reservoir 27 are further brought near the opening portion of the ink supply hole 28 when the suction operation is executed. It is attracted well. Thereby, the air bubbles in the reservoir 27 are well discharged from the nozzle 21 together with the ink. This is particularly effective when bubbles having a diameter larger than the inner diameter of the ink supply hole 28 are discharged.

(Other embodiments)
The embodiments of the present invention have been described above. Of course, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

For example, in the above-described embodiment, the example in which the gradually decreasing portion 60 is provided in the opening on the reservoir 27 side of the ink supply hole 28 has been described, but the gradually decreasing portion 60 may not necessarily be provided.

The present invention is characterized by the structure of the flow path formed on the flow path forming substrate, and other configurations are not particularly limited. For example, in the above-described embodiment, the actuator on the longitudinal vibration side composed of the diaphragm and the piezoelectric element is exemplified as the pressure generating means, but the configuration of the pressure generating means is not particularly limited, and for example, a flexural vibration type piezoelectric element May be an actuator, a heating element, or the like.

In the above-described embodiment, the ink jet recording head that ejects ink droplets is exemplified as the liquid ejecting head, and the ink jet recording apparatus is exemplified as the liquid ejecting apparatus. However, the present invention broadly includes a liquid ejecting head and a liquid ejecting head. The present invention is intended for general liquid ejecting apparatuses. Examples of the liquid ejecting head include a recording head used in an image recording apparatus such as a printer, a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an organic EL display, and an electrode formation such as an FED (field emission display). Electrode material ejecting heads used in manufacturing, bioorganic matter ejecting heads used in biochip production, and the like.

DESCRIPTION OF SYMBOLS 10 Inkjet recording apparatus, 11 Inkjet recording head, 21 Nozzle, 22 Nozzle plate, 23 Pressure generation chamber, 24 Flow path formation board | substrate, 25
Actuator, 26 Nozzle communication hole, 27 Reservoir, 28 Ink supply hole, 29 Bulkhead, 30 Diaphragm, 31 Piezoelectric element, 50 Reduced width part, 60 Reduced part

Claims (4)

A flow path forming substrate in which a plurality of pressure generation chambers communicating with nozzles for ejecting liquid droplets and a reservoir for storing liquid supplied to the plurality of pressure generation chambers are formed, and liquid from the nozzles in the pressure generation chamber A liquid ejecting head comprising pressure generating means for generating a pressure change for ejecting drops,
The pressure generating chamber and the reservoir are connected by a liquid supply hole formed in the flow path forming substrate,
The reservoir has a gradually decreasing width portion in which the width of the reservoir in the juxtaposition direction of the liquid supply holes gradually decreases toward the pressure generating chamber at the end on the liquid supply hole side. Jet head. 2. The liquid ejection according to claim 1, wherein the width gradually decreasing portion has a width of the reservoir gradually decreasing toward a central portion of the flow path forming substrate in a direction in which the liquid supply holes are arranged side by side. head. 3. The liquid jet head according to claim 1, wherein an end surface of the reservoir constituting the gradually decreasing width portion and opening the liquid supply hole is a spherical surface. 4. A liquid ejecting apparatus comprising the liquid ejecting head according to claim 1.

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