JP2003326712A - Ink jet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deformation of a channel unit due to a capping force while ensuring the cross-sectional area of a manifold required for attaining a good ejection performance. <P>SOLUTION: Each manifold 7 is provided on the same side as a nozzle with respect to a plurality of pressure chambers communicating with the nozzles wherein each pressure chamber is communicating with the manifold 7. On the nozzle side surface of the manifold 7, a reinforcing part 16 for decreasing the width at the bottom part 17 of the manifold 7 is formed. The reinforcing part 16 has a two-step shape. Even if a cap abuts against a corresponding nozzle plate 11 when the nozzle is covered with a purge cap, a nozzle plate 11 is not deformed because of presence of the reinforcing part 16. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head that forms an image on a printing surface by ejecting minute droplets of ink.

[0002]

2. Description of the Related Art As an ink jet head, Japanese Patent Laid-Open No.
As described in JP-A-01-246744, one or a plurality of manifolds (common ink chamber) are provided on the same side as the nozzles with respect to a plurality of pressure chambers that communicate with the nozzles.
There is known one having a flow path unit provided with. In general, an actuator unit is attached to the flow path unit so as to cover the open surface of each pressure chamber on the side opposite to the manifold. In this case, for example, a piezoelectric element is used as the actuator unit, and it is possible to eject ink from the nozzle by changing the volume in the pressure chamber by the piezoelectric effect.

[0003]

In the ink jet head as described above, the manifold formed in the flow path unit is configured so that ink can be smoothly and evenly supplied to each pressure chamber to obtain good ejection performance. Therefore, it is preferable that the cross-sectional area orthogonal to the ink flow direction is as large as possible. Therefore, in order to reduce the size of the flow path unit in which the nozzle and the manifold are provided on the same side of the pressure chamber, the distance from the ink ejection surface to the bottom surface of the manifold, that is, the wall thickness There is a current situation in which the size must be reduced considerably.

On the other hand, in the ink jet printer, the nozzle of the ink jet head is used for the purpose of preventing the ink in the nozzle from drying in the non-printing state and / or discharging the air or the like existing in the ink. Covering with a rubber cap is performed. It is preferable that the protruding portion (lip) of the cap is brought into contact with the ink ejection surface of the channel unit with a relatively strong force in order to block the outside air from the nozzle. Therefore, as described above, when the distance from the ink ejection surface to the bottom surface of the manifold is small, that is, the wall is thin, the wall of the channel unit may be deformed due to the capping force applied from the cap to the channel unit. is there.

Therefore, an object of the present invention is to provide an ink jet head capable of suppressing the deformation of the flow path unit due to the capping force while ensuring the cross-sectional area of the manifold required for obtaining good discharge performance. Is.

[0006]

In order to achieve the above object, an ink jet head according to a first aspect of the invention has a plurality of pressure chambers, each of which communicates with a nozzle, and the same side of the plurality of pressure chambers as the nozzle. And a flow path unit in which one or a plurality of manifolds are provided. Further, each pressure chamber communicates with one of the one or more manifolds, and a reinforcing portion that narrows the width of the bottom of the manifold is formed on the nozzle side surface of the manifold.

According to the first aspect of the present invention, since the reinforcing portion for narrowing the width of the bottom portion of the manifold is formed on the nozzle side surface of the manifold, the flow with respect to the capping force is ensured while ensuring the minimum required cross-sectional area of the manifold. The strength of the road unit can be increased.

In other words, the thickness of the surface of the manifold on the nozzle side is not simply increased, but the thin portion of this surface is made a part and the thickness is increased only by the reinforcing portion at the remaining portion. As a result, it is possible to achieve both the increase in strength and the securing of the necessary cross-sectional area, and it is possible to obtain an inkjet head that is resistant to deformation even when a capping force is applied and that has excellent ejection performance.

In the present invention, the bottom means the portion of the surface of the manifold on the nozzle side closest to the nozzle, and the bottom may be a flat surface or may be near the top of a curved surface. Good. Further, the bottom portion does not necessarily have to extend along the ink flow direction, and may extend along a direction inclined with respect to the ink flow direction.
However, from the viewpoint of smoothing the ink flow, it is preferable that the bottom portion extends along the ink flow direction.

An ink jet head according to a second aspect of the present invention is characterized in that the reinforcing portion has a step-like shape having a plurality of steps.

According to the second aspect, it is possible to further increase the strength of the flow path unit against the capping force while ensuring the minimum required cross-sectional area of the manifold.

An ink jet head according to a third aspect of the invention is characterized in that the flow path unit is composed of a plurality of plates.

According to the third aspect, the manifold can be easily made to have an optimum shape by changing the shape of each plate.

In the ink jet head according to a fourth aspect, the manifold extends in the same direction as the longitudinal direction of the flow path unit, and the reinforcing portion is formed so that the bottom portion has a zigzag shape. Is characterized by.

According to the present invention, when the cap extending in the longitudinal direction of the flow passage unit applies the capping force to the flow passage unit, the tip of the cap continuously contacts the portion corresponding to the bottom of the manifold. As a result, the strength of the flow path unit against the capping force can be further increased.

Here, the zigzag shape means that when an arbitrary straight line is drawn near the bottom along the extending direction,
The straight line means that a portion that overlaps with the bottom portion and a portion that does not overlap the bottom portion appear periodically.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a color ink jet printer incorporating an ink jet head according to an embodiment of the present invention. In FIG. 1, the printer head 63 of the color inkjet printer 100 has a total of four units arranged for each color in order to eject four colors (for example, cyan, magenta, yellow, and black) of ink on its main body frame 68. A plurality of piezoelectric ink jet heads 6 are fixed, and a total of four ink cartridges 61 filled with color inks are detachably attached to a main body frame 68. The main body frame 68 is fixed to a carriage 64 that is reciprocally driven in a linear direction by a drive mechanism 65. The platen roller 66 for feeding the paper has its axis aligned with the carriage 6.
It is arranged along the reciprocating direction of 4 and faces the inkjet head 6.

The carriage 64 has a guide shaft 71 and a guide plate 7 which are arranged in parallel with the support shaft of the platen roller 66.
It is slidably supported by 2. Pulleys 73 and 74 are supported near both ends of the guide shaft 71, and an endless belt 75 is stretched between these pulleys 73 and 74. The carriage 64 is fixed to the endless belt 75. In such a structure of the drive mechanism 65, when one pulley 73 is rotated in the forward and reverse directions by the drive of the motor 76, the carriage 64 is reciprocally driven linearly along the guide shaft 71 and the guide plate 72 accordingly. The printer head 63 is reciprocated.

The paper 62 is the ink jet printer 10.
Paper is fed from a paper feed cassette (not shown) provided on the side of 0, and the inkjet head 6 and the platen roller 66 are fed.
The ink is ejected from the ink jet head 6 after being guided to a space between the ink jet head 6 and a predetermined print. In FIG. 1, the paper feed mechanism and the paper discharge mechanism for the paper 62 are not shown.

The purging mechanism 67 is for forcibly sucking and removing defective ink containing air, dust, etc. accumulated inside the ink jet head 6. The purge mechanism 67 is provided on the side of the platen roller 66, and the arrangement position of the purge mechanism 67 is determined so as to face the inkjet head 6 when the printer head 63 reaches the reset position by the drive mechanism 65 described above. Has been.

A rubber purging cap 81 is attached to the purging mechanism 67. FIG. 2 shows an enlarged perspective view of the purge cap 81. The purge cap 81 includes a main body 81a having a substantially rectangular parallelepiped shape, and a lip 81b projecting annularly on an upper surface of the main body 81a so as to surround a nozzle row described later.
And a lip 81 on the upper surface of the main body 81a.
It communicates with a pump 82 described later through a hole 81c formed in a region surrounded by b.

When purging is performed, one of the four ink jet heads 6 is moved to a position facing the purge cap 81 by the carriage 64, and the cam 83 is driven by a drive source (not shown) to raise the purge cap 81. Lip 8 surrounding the nozzle 35 of the head
1b is the lower surface of the inkjet head 6 (ink ejection surface)
Abut. Then, the defective ink containing air or the like accumulated inside the inkjet head 6 is sucked by the pump 82 by driving the cam 83 and is discarded into the waste ink reservoir 84, so that the inkjet head 6 is restored. . As a result, the air can be removed at the time of the initial introduction of the ink to the inkjet head 6, or the inkjet head 6 can be removed from the defective ejection state caused by the growth of the internal air accompanying the printing.
Can be returned to the normal state.

The cap 85 shown in FIG. 1 covers all the nozzles of the four ink jet heads 6 on the carriage 64 which is returned to the reset position after printing is completed, and the solid component is deposited by vaporization of the liquid component of the ink. This is for preventing clogging of the ink flow path. The cap 85 is also
Similar to the purge cap 81 shown in FIG. 2, the main body has a rectangular parallelepiped shape and a lip protruding on the upper surface of the main body so as to draw an ellipse (however, the cap 85 has a hole like the purge cap 81). 81c is not provided). When printing is not performed, the cap 85 is raised by the action of the cam means (not shown) in conjunction with the movement of the carriage 64, the lip abuts on the ink ejection surface of the inkjet head 6, and all the nozzles are sealed.

FIG. 3 is a perspective view of the printer head 63 which is turned upside down. The main body frame 68 of the printer head 63 is, as shown in FIG.
Is formed in a substantially box shape with an open side), and four ink cartridges 61 can be detachably mounted from the open side, and the mounting portion is Is forming.

As shown in FIG. 3, at one side of the mounting portion of the main body frame 68, four ink supply passages 4 that can be connected to the ink discharge portions of the ink cartridges 61 are provided on the lower surface of the bottom plate 5 of the main body frame 68. (Inkjet head 6
To the surface where the is fixed). Further, a joint member 47 made of rubber or the like, which is brought into close contact with an ink supply hole 39 (described later) of the inkjet head 6, is attached to the lower surface of the bottom plate 5 so as to correspond to each ink supply passage 4.

As shown in FIG. 3, on the lower surface side of the bottom plate 5,
The four support portions 8 for arranging the four inkjet heads 6 in parallel are formed in a stepped shape. The inkjet head 6 is fixed to each of the supporting portions 8 with an ultraviolet curable adhesive.

FIG. 4 shows a perspective view of the ink jet head 6 according to this embodiment. The inkjet head 6 has a laminated flow channel unit 10, and a plate type piezoelectric actuator (hereinafter referred to as “actuator unit”) 20 is bonded to the flow channel unit 10 via an adhesive or an adhesive sheet. Stacked. Further, on the upper surface of the actuator unit 20, a flexible flat cable 40 for electrical connection with an external device is superposed and bonded with an adhesive. Bottom layer flow path unit 1
Many nozzles 35 are opened on the lower surface side of 0, and ink is ejected downward from each nozzle 35.

FIG. 5 is an exploded perspective view of the flow path unit 10.
6 is an exploded enlarged perspective view of the channel unit 10 (VI- in FIG. 5).
VI direction cross section) is shown respectively. As shown in FIGS. 5 and 6, the flow path unit 10 includes a nozzle plate 11, three manifold plates 13X, 13Y, 13Z, three spacer plates 14X, 14Y, 14Z, and a base plate 15 for a total of eight thin sheets. Are laminated and bonded to each other with an adhesive. The nozzle plate 11 is made of a polyimide material, and the other plates are made of stainless steel.

As shown in FIGS. 5 and 6, the nozzle plate 11 is provided with a large number of nozzles 35 for ejecting ink having a minute diameter (about 25 μm in the present embodiment) by pressing or laser processing. There is. The nozzles 35 are arranged in two rows in a staggered pattern at minute intervals along the longitudinal direction of the nozzle plate 11. The lower surface of the nozzle plate 11 forms an ink ejection surface.

As shown in FIG. 6, a large number of pressure chambers 36 are formed in the base plate 15 in two rows in a staggered arrangement along the longitudinal direction of the base plate 15. The specific shape of the pressure chambers 36 is shown in FIG. 6. As shown in this figure, each pressure chamber 36 is formed in a narrow width so that its longitudinal direction is orthogonal to the longitudinal direction of the base plate 15. ing.

Then, as shown in FIG. 7 which is an enlarged sectional view taken along line VII-VII in FIG.
One end portion 36a of each pressure chamber 36 formed in 5 is formed in a staggered arrangement in each of the three spacer plates 14X, 14Y, 14Z and the three manifold plates 13X, 13Y, 13Z. It communicates with the aforementioned nozzle 35 in the nozzle plate 11 via the through hole 37.

Ink supply holes 38 are formed in the upper spacer plate 14X adjacent to the base plate 15 at positions corresponding to the respective pressure chambers 36, and the ink supply holes 38 are formed.
Is connected to the other end 36 b of each pressure chamber 36. The intermediate spacer plate 14Y located immediately below is provided with a throttle 4
3 is elongated along the surface direction of the intermediate spacer plate 14Y (specifically, elongated parallel to the longitudinal direction of the pressure chamber 36), and is formed so as to penetrate in the plate thickness direction. The ink supply hole 38 communicates with one end of the throttle portion 43. Throttle part 4
The other end of the manifold 3 is connected to a manifold 7 to be described later through an introduction hole 44 formed to penetrate the lower spacer plate 14Z.
Communicate with. In the inkjet head 6 according to the present embodiment, when the flow passage cross-sectional area in the narrowed portion 43 is appropriately set,
Due to the diaphragm action, an actuator unit 2 described later
The ink pressure fluctuation caused by the operation of 0
The heading is restricted, and ink is effectively ejected from the nozzles 35.

As shown in FIG. 6, among the three manifold plates (13X, 13Y, 13Z), the upper manifold plate 13X closer to the spacer plates 14X to 14Z has two ink chamber upper parts 13 penetrating therethrough.
a is formed in a long hole shape extending in the longitudinal direction of the flow path unit 10 so as to sandwich the row of two through holes 37. On the other hand, the intermediate manifold plate 13Y adjacent to the lower side of the upper manifold plate 13X penetrates the intermediate manifold plate 13Y and is included in the two ink chamber upper portions 13a in plan view, that is, the two ink chamber intermediate portions 13b having a narrow width.
Is formed in a long hole shape extending in the longitudinal direction of the flow path unit 10. Further, the intermediate manifold plate 13
In the lower manifold plate 13Z adjacent to the lower side of Y, two ink chamber lower portions 13c penetrating therethrough and respectively included in the two ink chamber intermediate portions 13b in plan view, that is, two narrow ink chamber lower portions 13c are provided. It is formed in a long hole shape extending in the longitudinal direction of the unit 10. In this embodiment, the ink chamber upper part 13a, the intermediate part 13b, and the lower part 13c are formed by etching.

Then, the manifold plates 13X, 1
By stacking a total of 3 sheets of 3Y and 13Z, the ink chamber upper part 13a, the intermediate part 13b, and the lower part 1 whose upper and lower positions correspond to each other.
3c are joined to each other to form two manifolds 7, one on each side of the row of the two through holes 37, as shown in FIG. The upper surface of the manifold 7 is closed by the spacer plate 14Z, and the lower surface thereof is closed by the nozzle plate 11.

FIG. 8 shows an enlarged cross-sectional view of the flow path unit around the manifold. The actuator unit 20 is not shown in FIG. As is apparent from FIG. 8, in the manifold 7, the plane formed in the central portion in a plan view is the bottom portion (the bottom surface of the ink chamber lower portion 13c in this embodiment) 17 that is the lowest in the ink ejection surface. , And has a stepwise cross section with two step portions formed on both sides thereof. In other words, the portion 16a of the manifold plate 13Y protruding inward from the inner wall of the manifold plate 13X and the portion 16b of the manifold plate 13Z protruding inward from the inner wall of the manifold plate 13X are the reinforcement portions 16 of the manifold 7.
(Depicted by cross-hatching in FIG. 8), and the presence of the reinforcing portion 16 reinforces the width W of the bottom portion 17 of the manifold 7 by the protrusion of the reinforcing portion 16 from the inner wall of the manifold plate 13X. The width is narrower than the width of the ink chamber upper portion 13a where the portion is not provided. In the present embodiment, the bottom portion 17 is the flow path unit 1
It extends almost straight along the 0 longitudinal direction.

The two manifolds 7 are provided on both sides of the row of the through holes 37 because the pressure chambers 36 arranged in two rows.
This is to correspond to. That is, one of the two rows of pressure chambers is arranged in one manifold 7 and the remaining one
The pressure chamber group on the row side communicates with the other manifold 7, respectively. By configuring the inkjet head 6 in this way, it is also possible to supply ink of different colors to the two manifolds 7 and use it in a printing form in which one inkjet head 6 performs printing of two colors. The versatility of the head 6 is enhanced to reduce the types of parts. However, in the present embodiment, the same color ink is supplied to both manifolds 7,
The printing form is such that two rows of nozzles 35 perform high-resolution printing of a single color.

Returning to FIG. 5, the base plate 15 has 2
One ink supply hole 39a is provided, and two spacers 14X, 14Y, and 14Z are similarly provided with two ink supply holes 39b to 39d. By joining the base plate 15 and the spacer plates 14X, 14Y, and 14Z, the corresponding ink supply holes 39a to 39 are formed.
d are connected to each other, and two ink supply holes 39 corresponding to the above-mentioned two manifolds 7 are formed. In order to reduce the size of the inkjet head 6, the ink supply holes 39 are formed at positions near the ends of the rows of the pressure chambers 36, and the two ink supply holes 39 are arranged close to each other. ing.

With the configuration of the flow path unit 10 described above, the ink that has flowed into the manifold 7 from the ink supply hole 39 described above is introduced from the introduction hole 44 to the throttle portion 43 → the ink supply hole 3
8 to the other end 36b of each pressure chamber 36. Then, in each of the pressure chambers 36, the ink to which the ejection energy has been applied by the actuator unit 20 described later passes through the through holes 37 from the one end portion 36a thereof and is then ejected to the corresponding nozzle 35.

Next, the structure of the actuator unit will be described. FIG. 9 is an exploded enlarged perspective view of the actuator unit 20. As shown in FIGS. 7 and 9, the actuator unit 20 includes two piezoelectric sheets 21 and 22.
And a single insulating sheet 23 are laminated. On the upper surface of one piezoelectric sheet 21, a plurality of individual electrodes 2 having a narrow width corresponding to each pressure chamber 36 in the flow path unit 10 are provided.
4 are provided in a staggered arrangement. One end 24a of each individual electrode 24 is formed so as to be exposed on the left and right side surfaces orthogonal to the front and back surfaces 20a and 20b of the actuator unit 20.

On the upper surface of the other piezoelectric sheet 22, a common electrode 25 common to many pressure chambers 36 is provided. The one end 25a of the common electrode 25 is also connected to each individual electrode 2
Similar to the one end portion 24a of No. 4, it is formed so as to be exposed on the left and right side surfaces. A plurality of piezoelectric sheets 21 and 22 may be alternately laminated, and each region of the piezoelectric sheet 22 sandwiched between each individual electrode 24 and the common electrode 25 has a pressure generating portion (active area) corresponding to each pressure chamber 36. Part).

On the upper surface of the uppermost insulating sheet 23, the surface electrode 26 for each individual electrode 24 and the common electrode 2 are formed.
The surface electrodes 27 for 5 are provided side by side along the left and right side surfaces.

Further, on the left and right side surfaces, a first recessed groove 30 is formed at one end 24a of each individual electrode 24, and a second recessed groove 31 is formed at one end 25a of the common electrode 25 so as to extend in the stacking direction. It is provided. Side electrodes (not shown) that electrically connect the individual electrodes 24 and the surface electrodes 26 are provided in the first recessed grooves 30, and a common electrode 25 and a common electrode 25 are provided in the second recessed grooves 31. Side electrodes (not shown) that electrically connect to the surface electrodes 27 are formed respectively. Note that the electrodes 28 and 29 are electrodes in a discarded pattern.

The flow path unit 10 and the actuator unit 20 having the above-described structures are laminated so that the pressure chambers 36 in the flow path unit 10 and the individual electrodes 24 in the actuator unit 20 correspond to each other. In addition, the upper surface 2 of the actuator unit 20
0a, various wiring patterns (not shown) in the flexible flat cable 40 are connected to the surface electrodes 2
It is electrically joined to 6, 27.

When a voltage is applied between any of the individual electrodes 24 of the actuator unit 20 of the ink jet head 6 and the common electrode 25, the individual electrodes 2 of the piezoelectric sheet 22 to which the voltage is applied.
In the portion 4 (that is, the active portion), piezoelectric strain occurs in the stacking direction, and the volume of the pressure chamber 36 decreases. In this way, ejection energy is applied to the ink in the pressure chamber 36, and the ink is ejected in the form of liquid droplets from the nozzles 35, so that predetermined printing is performed on the paper 62.

In FIG. 10, the nozzle 35 has the purge cap 8
FIG. 3 is a cross-sectional view illustrating a state when covered with 1. Figure 11
FIG. 11 is an enlarged view of a main part of FIG. 10. In FIG. 10, the detailed structure of the flow path unit 10 and the illustration of the holes 81c are omitted.

As shown in FIG. 10, the purge cap 81
Contact the ink ejection surface of the inkjet head 6 so as to surround the row of nozzles 35 with a lip 81b. At this time, the lip 81b is often the ink as shown in FIG. It is located below the manifold 7 including the chamber upper part 13a, the intermediate part 13b, and the lower part 13c.

In the ink jet head 6 of this embodiment, since the reinforcing portion 16 as described above is formed in the manifold 7, the lip 81b of the purge cap 81 has a wall surface in the manifold 7 as shown in FIG. Even if it comes into contact with the position corresponding to the thinnest bottom portion 17,
Since the wall surface is stepwise thickened on both sides of the abutting portion, the abutting force is dispersed to the stepwise reinforcing portion 16 and the nozzle plate 11 forming the bottom portion 17 is not deformed.
In the present embodiment, the protruding length of the reinforcing portion 16 is preferably such that the width of the bottom portion 17 is smaller than the width of the tip portion of the lip 81b. By doing so, the strength of the bottom portion 17 against the capping force is significantly improved, and it is not necessary to design the printer so that the lip 81b does not contact the lower portion of the bottom portion 17.

Further, as a result, the bottom of the manifold 7 is brought close to the position close to the ink ejection surface to secure a sufficient volume of the manifold 7, and the strength of the flow path unit 10 against the capping force is increased and the pressure in each pressure chamber is increased. Achieves both smooth and uniform ink supply.

In particular, in the ink jet head 6 according to this embodiment, the flow path unit 10 has a plurality of plates 1.
1, 13X, 13Y, 13Z, 14X, 14Y, 14
Since it is composed of Z and 15, the manifold 7 can be easily made to have an optimum shape by appropriately changing the shapes of the manifold plates 13X, 13Y and 13Z. For example, by appropriately changing the width of the bottom portion 17 and the difference in length between the portions 16a and 16b of the reinforcing portion 16 according to specific design conditions, sufficient strength against the capping force and a minimum necessary amount can be obtained. The shape of the manifold 7 can be easily determined so as to have a cross-sectional area.

Although the capping force of the purge cap 81 has been described as an example here, the capping force is also generated in the cap 85. Therefore, the structure of this embodiment is also effective in that case.

Next, a modified example of the ink jet head according to the present embodiment will be described with further reference to FIGS. 12 to 14, the same members as those described above are designated by the same reference numerals.

FIG. 12 is a flow path unit 1 corresponding to FIG. 8 in the ink jet head according to the first modification.
It is an enlarged sectional view of 0 '. In this modification, as shown in FIG. 12, the ink chamber upper portion 13a, the intermediate portion 13b ', and the lower portion 1
The manifold 7'consisting of 3c has a stepwise cross section in which the plane formed in the center is the lowest bottom 17 of the ink ejection surface, and one step is formed on each side of the bottom. ing. More specifically, the inner wall positions of the two manifold plates 13X and 13Y are substantially the same, and the portion 16b protruding inward from the inner walls of the manifold plates 13X and 13Y of the manifold plate 13Z reinforces the manifold 7 '. Part 16 '(Fig. 12
It is drawn with cross hatching).

In this modification, the volume of the manifold 7'is larger than that of the manifold 7 of the first embodiment because the ink chamber intermediate portion 13b 'is enlarged. Although the strength with respect to the capping force is slightly lower than that, it is possible to realize smoother and more uniform ink supply to each pressure chamber.

FIG. 13 is a flow path unit 1 corresponding to FIG. 8 in the ink jet head according to the second modification.
It is an enlarged sectional view of 0 ". In this modification, as shown in FIG. 13, the ink chamber upper part 13a, the intermediate part 13b", and the lower part 1 are shown.
The manifold 7 ″ composed of 3c has a stepwise cross section in which the flat surface formed in the center portion is the lowest bottom portion 17 on the ink ejection surface, and one step portion is formed on each side thereof. More specifically, the inner wall positions of the two manifold plates 13Y and 13Z are substantially the same, and the portion 16a ″ protruding inward from the inner wall of the manifold plate 13X of these manifold plates Y and 13Z, 16b is the reinforcement portion 1 of the manifold 7 "
6 "(depicted by cross-hatching in FIG. 13).

In this modification, since the reinforcing effect of the reinforcing portion 16 "is increased by the amount of extension of the portion 16a" as compared with the above-described first embodiment, the cross-sectional area is slightly reduced, but the capping force is increased. Flow path unit 1 for
The strength of 0 "is extremely excellent.

FIG. 14 is a schematic plan view of a manifold in an ink jet head according to the third modification. This modification is the same as the above-described first modification, except that the reinforcing portion 16 is formed so that the bottom portion (which is represented by reference numeral 17 'in this example) has a rounded zigzag shape. In FIG. 14, the broken line indicates the upper part 13 of the ink chamber.
a, the inner wall position of the intermediate portion 13b ', and the solid line indicates the inner wall position of the lower portion of the ink chamber (in this example, it is represented by reference numeral 13c').

As is apparent from FIG. 14, in this modification, since the bottom portion 17 ′ has a zigzag shape along the longitudinal direction of the manifold, the lip 81 b of the purge cap 81 has the reinforcing portion 16 in the longitudinal direction. And the bottom portion 17 'alternately come into contact with each other. That is, since the lip 81b does not continuously contact the ink ejection surface corresponding to the bottom portion 17 'of the manifold, the strength of the flow path unit against the capping force becomes very large. Therefore, even if the volume of the reinforcing portion is relatively small, it is possible to secure a large cross-sectional area of the manifold 7, and it is possible to obtain an ink jet head having more excellent ink ejection performance.

In the present modification, the bottom portion 17 'has a rounded zigzag shape, but the bottom portion 17' may have an angular zigzag shape. Further, the pitch of the zigzag shape can be arbitrarily changed, but the strength becomes weaker as the pitch becomes larger, so it is preferable to make the pits small in a manufacturable range. Further, the present modification has been described as being based on the first modification, but it is also possible to employ the structure shown in FIG. 14 in the above-described embodiment or second modification, for example.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design changes are possible within the scope of the claims. Is. For example, in the above-described embodiment, the reinforcing portion has a stepped shape, but the shape of the reinforcing portion is not limited to this, and it is possible to have an arbitrary shape. Further, the bottom portion does not necessarily have to be provided at the central portion of the manifold, and may be provided at the end portion, for example. Further, in the above-described embodiment, the upper surface of the nozzle plate 11 exposed to the manifold 7 is the bottom portion 17, but the through hole may not be formed in the manifold plate 13Z and the upper surface may be the bottom portion.

Further, in the above-mentioned embodiment, the flow path unit is constructed by stacking a plurality of plates, but the number of stacked plates can be arbitrarily changed. Also, the number of manifold plates can be arbitrarily changed. Further, it is possible to form the manifold in the shape of a groove on one plate.

Further, in the above-described embodiment, the width of the nozzle plate is the same as that of the other plates, but the width of the nozzle plate is reduced so that only the portion near the nozzle is included, and the other portions are made smaller than the nozzle plate. May be covered with a protective member having high strength. However, according to the present invention, since the strength of the flow path unit is reinforced, it is not necessary to make such a design change.

Further, in the above-mentioned embodiment, the actuator unit is formed by laminating the piezoelectric sheets on which the electrodes are printed. However, the actuator unit is not limited to this, and the volume of the pressure chamber is changed. Any element other than the piezoelectric type may be used as long as it has an active portion that is deformed as described above.

[0064]

As described above, according to the first aspect of the present invention, while ensuring the minimum required sectional area of the manifold,
The strength of the flow path unit with respect to the capping force can be increased. According to the second aspect, it is possible to further increase the strength of the flow path unit against the capping force while ensuring the minimum required cross-sectional area of the manifold.
According to the third aspect, the manifold can be easily formed into the optimum shape. According to claim 4, the strength of the flow path unit against the capping force can be further increased.

[Brief description of drawings]

FIG. 1 is a perspective view of a color inkjet printer incorporating an inkjet head according to an embodiment of the present invention.

FIG. 2 is a perspective view of a purge cap included in the printer shown in FIG.

FIG. 3 is a perspective view of a printer head included in the printer shown in FIG.

FIG. 4 is an exploded perspective view of an inkjet head attached to the printer head shown in FIG.

5 is an exploded perspective view of a flow path unit in the inkjet head shown in FIG.

6 is an exploded enlarged perspective view of the flow path unit shown in FIG.

FIG. 7 is an enlarged cross-sectional view taken along the line VII-VII in FIG.

8 is an enlarged cross-sectional view around the manifold of the flow path unit shown in FIG.

9 is an exploded enlarged perspective view of an actuator unit in the inkjet head shown in FIG.

FIG. 10 is a cross-sectional view illustrating a state where the nozzle of the inkjet head is covered with a purge cap.

11 is an enlarged view of a main part of FIG.

FIG. 12 is an enlarged cross-sectional view of the flow path unit corresponding to FIG. 8 in the inkjet head according to the first modification example of the embodiment of the present invention.

FIG. 13 is an enlarged cross-sectional view of the flow path unit corresponding to FIG. 8 in the inkjet head according to the second modified example of the embodiment of the present invention.

FIG. 14 is a schematic plan view of a manifold in an inkjet head according to a third modification example of the embodiment of the present invention.

[Explanation of symbols]

6 inkjet head 7 manifold 10 flow path unit 16 Reinforcement part 17 bottom 20 actuator unit 35 nozzles 36 Pressure chamber 81 Purge cap 85 cap

Claims (4)

[Claims] 1. A flow path unit having a plurality of pressure chambers, each of which communicates with a nozzle, and one or a plurality of manifolds provided on the same side as the nozzle with respect to the plurality of pressure chambers. An ink jet head characterized in that each pressure chamber communicates with one of the one or a plurality of manifolds, and a reinforcing portion that narrows a width of a bottom portion of the manifold is formed on a surface of the manifold on the nozzle side. . 2. The ink jet head according to claim 1, wherein the reinforcing portion has a step-like shape having a plurality of steps. 3. The inkjet head according to claim 1, wherein the flow path unit is composed of a plurality of plates. 4. The manifold extends in the same direction as the longitudinal direction of the flow path unit, and the reinforcing portion is formed so that the bottom portion has a zigzag shape. The inkjet head according to any one of 1 to 3.