JP2003311959A - Ink jet head and ink jet printer comprising it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To align an actuator unit and a channel unit accurately. <P>SOLUTION: Each actuator 21 for varying the volume of each pressure chamber in a channel unit 4 has a trapezoidal shape straddling a plurality of pressure chambers. A plurality of actuator units 21 are arranged zigzag in two rows along the longitudinal direction of the channel unit 4 while being bonded to the surface of the channel unit 4 in which the pressure chambers are formed. Oblique sides of adjacent actuator units 21 are overlapping in the widthwise direction of the channel unit 4. <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 for printing by ejecting ink onto a print medium, and an ink jet printer having the ink jet head.

[0002]

2. Description of the Related Art In an ink jet printer, an ink jet head distributes ink supplied from an ink tank into a plurality of pressure chambers and selectively applies pressure to the pressure chambers to eject ink from nozzles. As one means for selectively applying pressure to the pressure chamber,
An actuator unit in which a plurality of ceramic piezoelectric sheets are stacked may be used.

As an example of such an ink jet head, a plurality of continuous flat plate-like piezoelectric sheets are laminated over a plurality of pressure chambers, and at least one of the piezoelectric sheets is common to many pressure chambers and has a ground potential. There is known one having one actuator unit sandwiched by a held common electrode and a large number of individual electrodes, that is, drive electrodes arranged at positions corresponding to the respective pressure chambers (see Patent Document 1). The portion of the piezoelectric sheet sandwiched between the individual electrode and the common electrode and polarized in the stacking direction is used as an active layer in the stacking direction by the so-called piezoelectric vertical effect when the individual electrodes on both sides are set to a potential different from that of the common electrode. Expand and contract. As a result, the volume inside the pressure chamber fluctuates, and ink can be ejected toward the print medium from the nozzle that communicates with the pressure chamber.

Therefore, in order to ensure good ink ejection performance in such an ink jet head, an actuator unit is installed in the flow path unit so that the position of the individual electrode with respect to each pressure chamber in a plan view becomes a predetermined position. Must be accurately aligned.

[0005]

[Patent Document 1] Japanese Unexamined Patent Publication No. 4-341852

[0006]

In the ink jet head as described above, due to various manufacturing restrictions, a flow path unit including an ink flow path including a pressure chamber and an actuator unit are separately manufactured. After that, it is often manufactured by adhering the both to each other using an adhesive with the pressure chamber inside. This bonding step is performed in a state in which the mark formed on the flow path unit and the mark formed on the actuator unit are aligned with each other.

However, since the flow path unit is generally a laminated body of a plurality of metal sheets, the piezoelectric sheet is manufactured through a sintering process. Therefore, as the size of the piezoelectric sheet in the actuator unit increases, the electrode becomes larger. The position accuracy of is reduced. Therefore, as the head becomes longer, it becomes difficult to align the pressure chamber in the flow path unit and the individual electrode in the actuator unit,
The head manufacturing yield is reduced.

On the other hand, the actuator unit is an expensive precision component and, at the same time, has a very brittle property because it is made of ceramic. Particularly, in the actuator unit having a polygonal contour shape, the corner portion is very likely to be chipped, and the damage loss thereof is a factor of increasing the manufacturing cost. Further, handling of the actuator unit is required to be performed very carefully so that the corner portion does not collide with other parts, which makes assembly work of the inkjet head difficult.

Accordingly, one object of the present invention is to provide an ink jet head in which the actuator unit and the flow path unit are accurately aligned.

Another object of the present invention is to provide an ink jet head in which the actuator unit is less likely to be damaged.

[0011]

According to one aspect of the present invention, there is provided a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source. A flow path unit arranged adjacent to each other, and a plurality of actuator units fixed to one surface of the flow path unit for changing the volume of the pressure chamber, each actuator unit corresponding to each pressure chamber. It has a plurality of pressure generating portions and is formed to have a size across the plurality of pressure chambers so that adjacent actuator units partially overlap each other in the width direction of the flow path unit. And a plurality of actuator units arranged along the longitudinal direction of the flow path unit, and each actuator unit has a large number of pressure generators. Other areas adjacent to the pressure generating section in the basic area, which is an additional area adjacent to the basic area in the width direction of the flow path unit An inkjet head (claim 1) comprising an additional region in which the pressure generating portion is formed corresponding to a gap portion between the unit and the pressure generating portion in the basic region, and an inkjet including the same. A printer (claim 7) is provided.

According to this, it becomes possible to position each of the plurality of actuator units with the flow path unit. Therefore, even if the head is lengthened, an increase in the amount of positional deviation between the electrode of each actuator unit and the pressure chamber is suppressed, and both can be accurately aligned. Therefore, good ink ejection performance is obtained, and the manufacturing yield of the head is improved. Moreover, since the pressure generating portion in the additional region provided in one certain actuator unit corresponds to the gap between the pressure generating portion in the basic region of the adjacent actuator unit, the pressure generating portion in the vicinity of the joint between the adjacent actuator units is The number of pressure generating parts does not decrease. Therefore, it is possible to obtain a head in which the number of pressure generating portions along the longitudinal direction of the channel unit does not substantially fluctuate.

According to still another aspect of the present invention, the pressure chamber includes a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source. The plurality of pressure chambers are arranged adjacent to each other along a plane. A plurality of flow path units, and a plurality of actuator units fixed to one surface of the flow path unit for changing the volume of the pressure chambers, wherein each actuator unit corresponds to each pressure chamber. Is formed to have a size that spans a plurality of the pressure chambers, and the adjacent actuator units are partially overlapped with each other in the width direction of the flow path unit. And an actuator unit arranged along the longitudinal direction of the inkjet printer. In this ink jet printer, each actuator unit is adjacent to a basic region in which a large number of the pressure generating portions are formed in a matrix and in the width direction of the flow path unit with respect to the basic region. An inkjet head having an additional region formed with, a drive circuit for driving the inkjet head, when driving the inkjet head, in the additional region, the pressure generating unit in the basic region, And a control unit for controlling the drive circuit so as to operate only the pressure generating portion corresponding to a gap portion between the pressure generating portion in the basic area of another adjacent actuator unit (claim) Item 8).

According to another aspect of the present invention, a flow path unit including a plurality of pressure chambers communicating with a nozzle for ejecting ink, the plurality of pressure chambers being arranged adjacent to each other along a plane, and the pressure unit. An actuator unit fixed to one surface of the flow path unit for changing the volume of the chamber, having a plurality of pressure generating portions corresponding to the respective pressure chambers and having a size across the plurality of pressure chambers. The actuator unit has a contour shape having five or more straight line portions, and each straight line portion forms an angle with the adjacent straight line portion at a right angle or an obtuse angle. A connected inkjet head is provided (claim 9).

According to this, by making all the corners of the actuator unit at right angles or obtuse angles, it becomes difficult for the actuator unit to be damaged at the time of manufacturing the ink jet head.

According to one aspect of the invention, a plurality of pressure chambers each having one end connected to a nozzle and the other end connected to an ink supply source are provided, and the plurality of pressure chambers are arranged adjacent to each other along a plane. A flow path unit and a plurality of actuator units fixed to one surface of the flow path unit for changing the volume of the pressure chamber, each actuator unit including a plurality of pressure generating units corresponding to each pressure chamber. An inkjet head is provided that includes a plurality of actuator units that are arranged along the longitudinal direction of the flow path unit and that have a size that spans the plurality of pressure chambers. Item 12).

According to this, it becomes possible to align each of the plurality of actuator units with the flow path unit. Therefore, even if the head is lengthened, an increase in the positional deviation amount between each actuator unit and the flow path unit is suppressed, and both can be accurately aligned. Therefore, good ink ejection performance is obtained, and the manufacturing yield of the head is improved.

[0018]

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

First, an ink jet head according to a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic view of an inkjet printer including this inkjet head. The inkjet printer 101 shown in FIG. 1 is a color inkjet printer having four inkjet heads 1. The printer 101 includes a paper feed unit 111 on the left side of the drawing.
However, a paper discharge unit 112 is configured on the right side of the drawing.

Inside the printer 101, a paper conveyance path is formed which flows from the paper feed unit 111 toward the paper discharge unit 112. Immediately downstream of the paper feeding unit 111, a pair of feed rollers 105a that nips and conveys a sheet that is an image recording medium,
105b is arranged. Pair of feed rollers 105
The sheet is sent from left to right in the figure by a and 105b. Two belt rollers 1 are provided in the middle of the paper transport path.
06 and 107, and an endless conveyor belt 108 that is wound so as to be stretched between both rollers 106 and 107 are arranged. The outer peripheral surface of the conveyor belt 108, that is, the conveyor surface is treated with silicone, and while holding the paper conveyed by the pair of feed rollers 105a and 105b on the conveyor surface of the conveyor belt 108 by its adhesive force, The belt roller 106 is driven to rotate clockwise (in the direction of arrow 104) in the figure so that it can be conveyed toward the downstream side (right side).

Pressing members 109a and 109b are disposed at the insertion and ejection positions of the paper with respect to the belt roller 106, respectively. Holding members 109a, 109b
Is for pressing the paper onto the carrying surface of the carrying belt 108 so that the paper on the carrying belt 108 does not float from the carrying surface, and to firmly adhere the paper to the carrying surface.

A peeling mechanism 110 is provided immediately downstream of the transport belt 108 along the paper transport path. The peeling mechanism 110 peels the sheet adhered to the conveyance surface of the conveyance belt 108 from the conveyance surface, and the right sheet ejection unit 112.
It is configured to be sent to.

The four ink jet heads 1 have head bodies 1a at their lower ends. The head body 1a is
Each of them has a rectangular cross section, and they are arranged close to each other so that the longitudinal direction thereof is a direction perpendicular to the paper conveyance direction (direction perpendicular to the paper surface of FIG. 1). That is, the printer 101 is a line printer. The bottom surfaces of the four head main bodies 1a face the paper transport path, and the bottom surfaces are provided with nozzles having a large number of ink ejection openings each having a minute diameter. Magenta, yellow, cyan, and black inks are ejected from each of the four head bodies 1a.

The head body 1a is arranged so that a small gap is formed between the lower surface of the head body 1a and the conveying surface of the conveying belt 108, and a sheet conveying path is formed in this gap portion. With this configuration, when the paper conveyed on the conveyor belt 108 sequentially passes immediately below the four head main bodies 1a, ink of each color is ejected from the nozzles toward the upper surface of the paper, that is, the printing surface. A desired color image can be formed on a sheet.

The ink jet printer 101 has a maintenance unit 117 for automatically performing maintenance on the ink jet head 1. The maintenance unit 117 includes four head bodies 1
Four caps 116 for covering the lower surface of a and a purging mechanism not shown are provided.

The maintenance unit 117 is used when the inkjet printer 101 is printing.
It is located at a position (retracted position) immediately below the paper feeding unit 111. Then, when a predetermined condition is satisfied after the printing is completed (for example, when the printing operation is not performed for a predetermined time, or when the power of the printer 101 is turned off), the four head main bodies are used. 1a is moved to a position immediately below, and at this position (cap position), the cap 116 covers the lower surface of the head body 1a,
The ink of the nozzle portion of the head body 1a is prevented from drying.

The belt rollers 106 and 107 and the conveyor belt 108 are supported by the chassis 113. The chassis 113 has a cylindrical member 115 arranged below it.
It is placed on top. The cylindrical member 115 is rotatable about a shaft 114 attached at a position deviated from the center thereof. Therefore, when the height of the upper end of the cylindrical member 115 changes with the rotation of the shaft 114, the chassis 113 moves up and down accordingly. Maintenance unit 1
When moving 17 from the retracted position to the cap position,
The cylindrical member 115 is rotated in advance by an appropriate angle to make the chassis 1
13, transport belt 108 and belt rollers 106, 10
It is necessary to lower 7 from the position shown in FIG. 1 by an appropriate distance to secure a space for moving the maintenance unit 117.

In a region surrounded by the conveyor belt 108, a substantially rectangular parallelepiped shape (conveyance) which supports the inkjet head 1 from the inner peripheral side by contacting the lower surface of the conveyor belt 108 located at a position facing the ink jet head 1 (conveyance). The guide 121 having the same width as the belt 108)
Are arranged.

Next, the structure of the ink jet head 1 according to this embodiment will be described in more detail. Figure 2
FIG. 3 is a perspective view of the inkjet head 1. Figure 3
FIG. 3 is a sectional view taken along line III-III in FIG. 2. 2 and 3
As shown in FIG. 1, the inkjet head 1 according to the present embodiment has a head main body 1a having a rectangular planar shape extending in one direction (main scanning direction) and a base 131 for supporting the head main body 1a. ing. In addition to the head body 1a, the base 131 supports a driver IC 132 and a substrate 133 that supply drive signals to the individual electrodes 35a and 35b (see FIG. 6).

As shown in FIG. 2, the base 131 is partially bonded to the upper surface of the head main body 1a to support the head main body 1a, and is bonded to the upper surface of the base block 138. Base block 13
8 and a holder 139 for holding 8. The base block 138 is a substantially rectangular parallelepiped member having a length substantially the same as the length of the head body 1a in the lengthwise direction. Base block 138 made of metallic material such as stainless steel
Has a function as a lightweight structure that reinforces the holder 139. The holder 139 includes a holder main body 141 arranged on the head main body 1a side, and a pair of holder support portions 142 extending from the holder main body 141 to the side opposite to the head main body 1a. A pair of holder support parts 14
2 is a plate-shaped member, and is a holder body 14
They are provided in parallel with each other at a predetermined interval along the lengthwise direction of 1.

A pair of skirts 141a projecting downward are provided at both ends of the holder body 141 in the sub-scanning direction (direction orthogonal to the main scanning direction). Here, since the pair of skirts 141a are formed over the entire width in the longitudinal direction of the holder body 141, the pair of skirts 141a form a substantially rectangular parallelepiped groove 141b on the lower surface of the holder body 141. ing. The base block 138 is housed in the groove 141b. The upper surface of the base block 138 and the holder body 141
The bottom surface of the groove portion 141b is bonded with an adhesive. The thickness of the base block 138 is the holder body 14
Since it is slightly larger than the depth of the first groove portion 141b, the lower end portion of the base block 138 protrudes below the skirt portion 141a.

Inside the base block 138, an ink reservoir 3 which is a substantially rectangular parallelepiped void (hollow region) extending in the longitudinal direction is formed as a flow path of ink supplied to the head main body 1a. There is. Base block 138
On the lower surface 145 of the opening 3 b communicating with the ink reservoir 3.
(See FIG. 4) are formed. Ink pool 3
Is connected to a main ink tank (ink supply source) (not shown) in the printer body by a supply tube (not shown). Therefore, the ink reservoir 3 is appropriately replenished with ink from the main ink tank.

The lower surface 145 of the base block 138 projects below the periphery in the vicinity of the opening 3b. The base block 138 is in contact with the flow path unit 4 (see FIG. 3) of the head body 1a only in the portion 145a of the lower surface 145 near the opening 3b. Therefore, the region of the lower surface 145 of the base block 138 other than the portion 145a near the opening 3b is separated from the head body 1a, and the actuator unit 21 is arranged in this separated portion.

The driver IC 132 is fixed to the outer surface of the holder support portion 142 of the holder 139 via an elastic member 137 such as sponge. A heat sink 134 is closely arranged on the outer surface of the driver IC 132. The heat sink 134 is a member having a substantially rectangular parallelepiped shape and efficiently dissipates heat generated by the driver IC 132. The driver IC 132 includes a flexible printed wiring board (FPC: Flexible Printed Circuit) which is a power feeding member.
cuit) 136 is connected. The FPC 136 connected to the driver IC 132 is electrically joined to the substrate 133 and the head body 1a by soldering. A substrate 133 is arranged above the driver IC 132 and the heat sink 134 and outside the FPC 136. Between the upper surface of the heat sink 134 and the substrate 133, and between the lower surface of the heat sink 134 and the FPC 136.
And a seal member 149 are bonded to each other.

The FPC 136 is provided between the lower surface of the skirt portion 141a of the holder body 141 and the upper surface of the flow path unit 4.
The seal member 150 is arranged so as to sandwich the. That is, the FPC 136 includes the flow path unit 4 and the holder body 1.
It is fixed to 41 by a seal member 150. This prevents the head body 1a from bending when the head body 1a is elongated, and the actuator unit 21 and the FPC 136 are prevented.
It is possible to prevent stress from being applied to the connection portion with and to securely hold the FPC 136.

As shown in FIG. 2, in the vicinity of the lower corner of the inkjet head 1 in the main scanning direction, six convex portions 30a are evenly spaced along the side wall of the inkjet head 1. These protruding portions 30a are portions provided at both ends in the sub-scanning direction of the nozzle plate 30 (see FIG. 7) in the lowermost layer of the head body 1a. That is, the nozzle plate 30 is bent about 90 degrees along the boundary line between the protruding portion 30a and other portions.
The protruding portions 30a are provided at positions corresponding to the vicinity of both ends of sheets of various sizes used for printing in the printer 101. Since the bent portion of the nozzle plate 30 has a rounded shape rather than a right angle, the jam of the sheet that is caused when the leading edge of the sheet conveyed in the direction close to the head 1 comes into contact with the side surface of the head 1. That is, jamming is less likely to occur.

FIG. 4 is a schematic plan view of the head body 1a. In FIG. 4, the ink reservoir 3 formed in the base block 138 is virtually depicted by a broken line.
As shown in FIG. 4, the head body 1a has a rectangular planar shape extending in one direction (main scanning direction). The head main body 1a has a number of pressure chambers 10 to be described later and a flow path unit 4 in which an ink ejection port 8 at the tip of a nozzle (see also FIGS. 5, 6, and 7) is formed, and the upper surface thereof is provided. A plurality of trapezoidal actuator units 21 arranged in two rows in a zigzag pattern are bonded. Each actuator unit 21 is arranged such that its parallel facing sides (upper side and lower side) are along the longitudinal direction of the flow path unit 4. The hypotenuses of the adjacent actuator units 21 overlap each other in the width direction of the flow path unit 4.

The lower surface of the flow path unit 4 corresponding to the adhesion area of the actuator unit 21 is an ink ejection area. As will be described later, a large number of ink ejection openings 8 are arranged in a matrix on the surface of the ink ejection area. Further, in the base block 138 arranged above the flow path unit 4, the ink reservoir 3 is formed along the longitudinal direction thereof. The ink reservoir 3 communicates with an ink tank (not shown) through an opening 3a provided at one end thereof and is always filled with ink.
In the ink reservoir 3, two openings 3b are arranged in pairs along the extending direction, and the openings 3b are provided in a zigzag manner in a region where the actuator unit 21 is not provided.

FIG. 5 is an enlarged view of the area surrounded by the alternate long and short dash line drawn in FIG. As shown in FIGS. 4 and 5,
The ink reservoir 3 communicates with the manifold 5 in the flow channel unit 4 located below the ink reservoir 3 through the opening 3b. The opening 3b is provided with a filter (not shown) for capturing dust and the like contained in the ink. The front end of the manifold 5 is branched into two to form a sub-manifold 5a. One actuator unit 21
Two sub-manifolds 5a enter into the lower part of the actuator unit 21 from two openings 3b located on both sides of the inkjet head 1 in the longitudinal direction. That is, one actuator unit 2
A total of four sub-manifolds 5 a extend along the longitudinal direction of the inkjet head 1 in the lower part of the nozzle 1.
Each sub-manifold 5a is filled with the ink supplied from the ink reservoir 3.

FIG. 6 is an enlarged view of the region surrounded by the alternate long and short dash line drawn in FIG. As shown in FIGS. 5 and 6,
On the upper surface of the actuator unit 21, individual electrodes 35a having a substantially rhombic plan shape are regularly arranged in a matrix, and at positions inside the actuator unit 21 that vertically overlap with the individual electrodes 35a. An individual electrode 35b having the same shape as the individual electrode 35a is arranged. In addition, a large number of ink ejection openings 8 are regularly arranged in a matrix on the surface of the ink ejection area corresponding to the actuator unit 21 of the flow path unit 4. Inside the flow path unit 4, substantially rhombic pressure chambers (cavities) 10 each having a planar shape slightly larger than the individual electrodes 35a and 35b and communicating with each ink ejection port 8 and apertures 12 are arranged in a matrix. It is regularly arranged. The pressure chamber 10 is formed at a position corresponding to the individual electrodes 35a and 35b, and most of the individual electrodes 35a and 35b are included in the region of the pressure chamber 10 in a plan view. 5 and 6, in order to make the drawings easy to understand, the pressure chamber 10 and the aperture 12 and the like in the actuator unit 21 or the flow path unit 4 which should be drawn by broken lines are drawn by solid lines.

FIG. 7 is a partial sectional view along the longitudinal direction of the pressure chamber of the head body 1a depicted in FIG. As can be seen from FIG. 7, each ink ejection port 8 is formed at the tip of a tapered nozzle. Each ink ejection port 8 communicates with the sub-manifold 5a via a pressure chamber 10 (length 900 μm, width 350 μm) and an aperture 12. In this manner, the ink jet head 1 is provided with the ink flow path 32 that extends from the ink tank to the ink reservoir 3, the manifold 5, the sub-manifold 5a, the aperture 12 and the pressure chamber 10 to reach the ink ejection port 8.

Further, as apparent from FIG. 7, the pressure chamber 1
0 and the aperture 12 are provided at different heights.
As a result, as shown in FIG. 6, in the flow path unit 4 corresponding to the ink ejection region below the actuator unit 21, the aperture 12 communicating with one pressure chamber 10 is connected to the pressure chamber adjacent to the pressure chamber 10. It can be arranged at the same position as 10 in a plan view. As a result, since the pressure chambers 10 are in close contact with each other and are arranged at high density, high-resolution image printing is realized by the inkjet head 1 having a relatively small occupied area.

The pressure chambers 10 are arranged in the planes shown in FIGS. 5 and 6 in the longitudinal direction of the ink jet head 1 (first arrangement direction) and in a direction slightly inclined from the width direction of the ink jet head 1 (second arrangement). Direction) in the ink ejection area. The first arrangement direction and the second arrangement direction form an angle θ slightly smaller than a right angle. The ink ejection openings 8 are arranged at 50 dpi in the first arrangement direction. On the other hand, 12 pressure chambers 10 are arranged in the second arrangement direction so that 12 pressure chambers are included in the ink ejection region corresponding to one actuator unit 21. As a result, twelve ink ejection openings 8 are present in the entire width of the inkjet head 1 in a range separated by the distance between two ink ejection openings 8 adjacent in the first arrangement direction. It should be noted that at both ends (corresponding to the hypotenuse of the actuator unit 21) of each ink ejection area in the first arrangement direction, a complementary relationship with an ink ejection area corresponding to another actuator unit 21 facing in the width direction of the inkjet head 1 is provided. Therefore, the above condition is satisfied. Therefore, in the ink jet head 1 according to the present embodiment, ink is sequentially ejected from a large number of ink ejection openings 8 arranged in the first and second arrangement directions as the ink jet head 1 moves in the width direction relative to the paper. By ejecting droplets, printing can be performed at 600 dpi in the main scanning direction.

Next, the structure of the flow path unit 4 will be described in more detail with reference to FIG. FIG. 8 is a schematic diagram showing the positional relationship among the pressure chamber 10, the ink discharge port 8 and the aperture (restricted flow path) 12. As shown in FIG. 8, the pressure chambers 10 have a predetermined spacing of 50 dp in the first arrangement direction.
i are arranged in rows. The rows of such pressure chambers 10 are arranged in 12 rows in the second arrangement direction, and as a whole, the pressure chambers 10 are two-dimensionally arranged in the ink ejection region corresponding to one actuator unit 21.

There are two types of pressure chambers, a pressure chamber 10a in which the nozzle is connected to the upper acute angle portion in FIG. 8 and a pressure chamber 10b in which the nozzle is connected to the lower acute angle portion. The plurality of pressure chambers 10a and the plurality of pressure chambers 10b are both arranged in the first arrangement direction to form pressure chamber rows 11a and 11b, respectively. As shown in FIG. 8, in the ink ejection area corresponding to one actuator unit 21,
Two pressure chamber rows 11a are arranged in order from the lower side in FIG.
Two pressure chamber rows 11b are arranged adjacent to the upper side thereof. Such a combination of two pressure chamber rows 11a and two pressure chamber rows 11b makes up a set of four pressure chamber rows, and a set of pressure chamber rows forms an ink discharge corresponding to one actuator unit 21. Within the region, they are arranged three times from the bottom. The straight line connecting the upper acute corners of the pressure chambers in each pressure chamber row 11a, 11b intersects the lower oblique side of each pressure chamber in the pressure chamber row adjacent to the pressure chamber row from above.

As described above, the first pressure chamber row 11a and the second pressure chamber row 11 in which the arrangement positions of the nozzles connected to the pressure chambers 10 are different when viewed from the direction perpendicular to the paper surface of FIG.
By arranging b and 2 adjacent to each other, the pressure chambers 10 are regularly aligned as a whole. On the other hand, the nozzles are arranged collectively in the central region in a set of pressure chamber rows in which these four pressure chamber rows are one set.
As a result, as described above, when four pressure chamber rows are set as one set and the sets of pressure chamber rows are repeatedly arranged three times from the lower side, the boundary neighborhood region between the sets of pressure chamber rows, that is, Areas where nozzles do not exist are formed on both sides of the set of four pressure chamber rows. A wide sub-manifold 5a for supplying ink to each pressure chamber 10 is extended there. In the present embodiment, in the ink ejection area corresponding to one actuator unit 21, one is provided on the lower side in the drawing, between the lowest pressure chamber row set and the second pressure chamber row set. 4 and a total of four sub-manifolds 5a having a wide width are provided in the first arrangement direction.

As shown in FIG. 8, the nozzles communicating with the ink ejection openings 8 for ejecting ink are 50d in the first arrangement direction, corresponding to the pressure chambers 10 regularly arranged in this direction.
They are arranged at equal intervals of pi. Further, unlike the case where the twelve pressure chambers 10 are regularly arranged in the second arrangement direction that intersects the first arrangement direction at the angle θ, the twelve pressure chambers corresponding to the twelve pressure chambers 10 are also arranged. As described above, the nozzles are connected to the upper acute-angled portion and the lower acute-angled portion of the pressure chamber 10, and are not regularly arranged in the second arrangement direction at regular intervals. .

On the other hand, when the nozzles are always in communication with the acute-angled portions on the same side of the pressure chamber 10, the nozzles are also regularly arranged in the second arrangement direction at regular intervals.
In other words, in this case, the nozzle is 1 from the lower side to the upper side in the figure.
Each time the row of pressure chambers rises, they are arranged so as to be displaced in the first arrangement direction by an interval corresponding to 600 dpi which is the resolution at the time of printing. On the other hand, in this inkjet head, a total of four pressure chamber rows, that is, two pressure chamber rows 11a and two pressure chamber rows 11b, are set as one set, and these are arranged three times from the lower side. Therefore, the displacement of the nozzle position in the first arrangement direction is not always the same every time one row of pressure chambers rises from the lower side to the upper side in the drawing.

In the ink jet head 1, a width (about 508.0 μm) corresponding to 50 dpi in the first arrangement direction.
Consider the strip-shaped region R that has the following and extends in the direction orthogonal to the first arrangement direction. In this strip region R, 1
In each of the two pressure chamber rows, the number of nozzles is 1
There is only one. That is, when such a strip region R is partitioned at an arbitrary position in the ink ejection region corresponding to one actuator unit 21, 12 nozzles are always distributed in this strip region R. The positions of the points obtained by projecting these 12 nozzles on a straight line extending in the first arrangement direction are the resolutions at the time of printing.
They are separated by a distance corresponding to 00 dpi.

These 12 nozzles are described as (1) to (12) in order from the position on the left where 12 nozzles belonging to one strip region R are projected on a straight line extending in the first arrangement direction. These 12 nozzles are (1), (7), (2), (8), (5), (11), (6), (12),
They are arranged in the order of (9), (3), (10), and (4).

In the thus constructed ink jet head 1, by appropriately driving the active layer in the actuator unit 21, it is possible to draw characters and figures having a resolution of 600 dpi. That is, specific characters and figures can be printed on the print medium by sequentially and selectively driving the active layers corresponding to the 12 rows of pressure chambers in accordance with the conveyance of the print medium.

For example, a case of printing a straight line extending in the first array direction at a resolution of 600 dpi will be described. First, the case where the nozzle communicates with the acute angle portion on the same side of the pressure chamber 10 will be briefly described. In this case, in response to the conveyance of the print butterfly, ink is started to be ejected from the nozzles in the pressure chamber row located at the bottom in FIG. 8 and sequentially belongs to the pressure chamber row adjacent to the upper side. Select a nozzle to eject ink. As a result, ink dots are formed adjacent to each other at an interval of 600 dpi in the first arrangement direction. Finally, a straight line extending in the first array direction is drawn with a resolution of 600 dpi as a whole.

On the other hand, in the present embodiment, ink is started to be ejected from the nozzles in the pressure chamber row 11a located at the bottom in FIG. Ink is selected by selecting a nozzle that communicates with the chamber. At this time, since the displacement of the nozzle position in the first arrangement direction is not always the same every time one row of pressure chambers is moved upward from the lower side, the print medium is sequentially formed along the first arrangement direction as the print medium is conveyed. Ink dots are 600dp
The intervals of i are not equal.

That is, as shown in FIG. 8, in response to the conveyance of the print medium, first, ink is ejected from the nozzle (1) communicating with the lowermost pressure chamber row 11a in the figure to print. A space corresponding to 50 dpi on the medium (approximately 508.0 μm
In m), a dot row is formed. After that, as the print medium is conveyed, the position where the straight line is formed is the second pressure chamber row 1 from the bottom.
When the position of the nozzle (7) communicating with 1a is reached, ink is ejected from this nozzle (7). As a result, 2 dots are formed at the position (about 42.3 μm × 6 = about 254.0 μm) displaced in the first arrangement direction by 6 times the interval (about 42.3 μm) corresponding to 600 dpi from the initially formed dot position. The th ink dot is formed.

Next, when the straight line forming position reaches the position of the nozzle (2) communicating with the third pressure chamber row 11b from the bottom as the print medium is conveyed, ink is ejected from the nozzle (2). It As a result, 6 dots from the initial dot position
A third ink dot is formed at a position displaced in the first arrangement direction by an interval (about 42.3 μm) corresponding to 00 dpi. Further, when the straight line formation position reaches the position of the nozzle (8) communicating with the fourth pressure chamber row 11b from the bottom as the print medium is conveyed, ink is ejected from the nozzle (8). As a result, the distance from the position of the first formed dot is 7 for the interval (about 42.3 μm) corresponding to 600 dpi.
A position displaced by a factor of 2 in the first array direction (approximately 42.3 μm ×
7 = about 296.3 μm), the fourth ink dot is formed. Further, as the print medium is conveyed, the nozzle in which the straight line forming position communicates with the fifth pressure chamber row 11a from the bottom.
When the position (5) is reached, ink is ejected from the nozzle (5). As a result, 60 dots from the dot position that was initially formed
A position (about 42.3 μm × 4 =) displaced in the first array direction by four times the distance corresponding to 0 dpi (about 42.3 μm)
A fifth ink dot is formed at about 169.3 μm).

In the same manner as described above, ink dots are sequentially formed while sequentially selecting nozzles communicating with the pressure chambers 10 located from the lower side to the upper side in the drawing. At this time, when the nozzle number shown in FIG. 8 is N, (magnification n = N-1) ×
Ink dots are formed at positions displaced from the initially formed dot positions in the first arrangement direction by an amount corresponding to (an interval corresponding to 600 dpi). When 12 nozzles are finally selected, between the ink dots formed by the nozzle (1) in the lowermost pressure chamber row 11a in the figure at an interval (about 508.0 μm) corresponding to 50 dpi. Are connected by 12 dots formed at intervals (about 42.3 μm) corresponding to 600 dpi, for a total of 60
It is possible to draw a straight line extending in the first arrangement direction with a resolution of 0 dpi.

Next, the sectional structure of the ink jet head 1 according to this embodiment will be described. FIG. 9 is a partially exploded perspective view of the head main body 1a depicted in FIG. Figure 1
0 is an enlarged cross-sectional view of the region surrounded by the alternate long and short dash line drawn in FIG. 7 as seen from the lateral direction. As shown in FIGS. 7 and 9, the main parts on the bottom side of the inkjet head 1 include an actuator unit 21, a cavity plate 22, a base plate 23, an aperture plate 24, from the top.
Supply plate 25, manifold plates 26, 2
7, 28, cover plate 29 and nozzle plate 30
The sheet structure has a laminated structure in which a total of 10 sheet materials are laminated. Of these, the flow path unit 4 is composed of nine plates excluding the actuator unit 21.

As will be described later in detail, the actuator unit 21 has five piezoelectric sheets 41 to 45 (see FIG. 10) laminated and electrodes arranged so that the uppermost layer of them and the first layer adjacent thereto. Only two layers are layers having a portion that becomes an active layer when an electric field is applied (hereinafter, simply referred to as “layer having an active layer”), and the remaining three layers are inactive layers. The cavity plate 22 is
It is a metal plate provided with a large number of substantially rhombic openings corresponding to the pressure chambers 10. As for the base plate 23, one pressure chamber 10 of the cavity plate 22 is
0 is a metal plate provided with a communication hole between 0 and the aperture 12 and a communication hole from the pressure chamber 10 to the ink ejection port 8. The aperture plate 24 is provided for the pressure chamber 10 of the cavity plate 22 with respect to the aperture plate 12.
In addition to the above, the metal plate is provided with a communication hole from the pressure chamber 10 to the ink ejection port 8. The supply plate 25 includes one pressure chamber 10 of the cavity plate 22.
2 is a metal plate provided with a communication hole between the aperture 12 and the sub-manifold 5a and a communication hole from the pressure chamber 10 to the ink ejection port 8. The manifold plates 26, 27, and 28 are metal plates in which, in addition to the sub-manifold 5a, a communication hole from the pressure chamber 10 to the ink ejection port 8 is provided for each pressure chamber 10 of the cavity plate 22. Cover plate 29
Is a metal plate in which a communication hole from the pressure chamber 10 to the ink ejection port 8 is provided for each pressure chamber 10 of the cavity plate 22. Nozzle plate 30
Is a metal plate provided with a tapered ink ejection port 8 functioning as a nozzle for each pressure chamber 10 of the cavity plate 22.

These ten sheets 21 to 30 are shown in FIG.
The ink channels 32 are aligned with each other and stacked so that the ink flow paths 32 as shown in FIG. The ink flow path 32 is
First from the sub-manifold 5a, it extends upwards, horizontally in the aperture 12, then further upwards, again horizontally in the pressure chamber 10, and then diagonally downward in the direction away from the aperture 12 and then vertically. Heading downward to the ink ejection port 8.

As shown in FIG. 10, the actuator unit 21 has five piezoelectric sheets 41, 42, 43, which are formed to have the same thickness of about 15 μm.
44 and 45 are included. These piezoelectric sheets 41 to 45
Is a continuous layered flat plate (continuous flat plate layer) so as to be arranged over a large number of pressure chambers 10 formed in one ink discharge region in the inkjet head 1.
By arranging the piezoelectric sheets 41 to 45 as a continuous flat plate layer over a large number of pressure chambers 10, it is possible to arrange the individual electrodes 35a and 35b at a high density by using, for example, a screen printing technique. . Therefore, the pressure chambers 10 formed at the positions corresponding to the individual electrodes 35a and 35b can be arranged at high density, and high-resolution images can be printed. Piezoelectric sheets 41-4
5 is lead zirconate titanate (PZ) having ferroelectricity.
It is made of a T) -based ceramic material.

A common electrode 34a having a thickness of about 2 μm formed on the entire surface of the sheet is interposed between the uppermost piezoelectric sheet 41 and the adjacent piezoelectric sheet 42 below the sheet. Similarly, between the piezoelectric sheet 43 adjacent to the lower layer of the piezoelectric sheet 42 and the piezoelectric sheet 44 adjacent to the lower layer thereof, the common electrode 34b having a thickness of about 2 μm and formed similarly to the common electrode 34a is interposed. . In addition, the piezoelectric sheet 4
1, an individual electrode 35a having a planar shape similar to that of the pressure chamber 10 (length 850 μm, width 250 μm) and having a projection region in the stacking direction in the pressure chamber region and having a thickness of about 1 μm It is formed for each chamber 10 (see FIG. 6). Further, between the piezoelectric sheet 42 and the piezoelectric sheet 43, an individual electrode 35b having a thickness of about 2 μm and formed similarly to the individual electrode 35a is interposed. On the other hand, no electrodes are arranged between the piezoelectric sheet 44 adjacent to the lower side of the piezoelectric sheet 43 and the piezoelectric sheet 45 adjacent to the lower side thereof, and below the piezoelectric sheet 45. Electrodes 34a, 34
b, 35a, and 35b are made of a metal material such as Ag-Pd.

The common electrodes 34a and 34b are grounded in a region (not shown). Thereby, the common electrode 34
a and 34b are equally kept at the ground potential in the regions corresponding to all the pressure chambers 10. In addition, the individual electrodes 35a and 35b are individually lead wires (not shown) wired in the FPC 136 for each individual electrode 35 so that the potentials of the electrodes corresponding to the respective pressure chambers 10 can be controlled. , And is connected to the driver IC 132 via this lead wire. At this time, the individual electrodes 35a and 35b paired up and down may be connected to the driver IC 132 via the same lead wire. The common electrodes 34a and 34b may be formed in a larger number for each pressure chamber 10 than the pressure chamber 10 so that the projection region in the stacking direction includes the pressure chamber region, or the projection region may have a pressure region. Many pressure chambers 10 that are slightly smaller than the pressure chambers 10 may be formed so as to be included in the chamber region, and it is not always necessary that one conductive sheet is formed on the entire surface of the sheet. However, at this time, it is necessary that the common electrodes are electrically connected so that all the portions corresponding to the pressure chamber 10 have the same potential.

In the ink jet head 1, the piezoelectric sheets 41 to 45 are polarized in the thickness direction. That is, the actuator unit 21 includes the three piezoelectric sheets 41 to 41 (that is, separated from the pressure chamber 10) on the upper side.
A so-called unimorph type structure is provided in which 43 is a layer in which an active layer is present and two lower piezoelectric sheets 44, 45 (that is, close to the pressure chamber 10) are inactive layers. Therefore, when the individual electrodes 35a and 35b are set to a predetermined positive or negative potential, for example, if the electric field and the polarization are in the same direction, the electric field application portion sandwiched between the electrodes in the piezoelectric sheets 41 to 43 is the active layer (pressure generating portion). ), And contracts in the direction perpendicular to the polarization direction by the piezoelectric lateral effect. On the other hand, the piezoelectric sheets 44 and 45
Does not contract spontaneously because it is not affected by the electric field, so the upper piezoelectric sheets 41 to 43 and the lower piezoelectric sheet 4
There is a difference in the strain in the direction perpendicular to the polarization direction between Nos. 4 and 45, and the piezoelectric sheets 41 to 45 tend to be deformed so as to be convex toward the inactive side (unimorph deformation). At this time, as shown in FIG.
The lower surfaces of the piezoelectric sheets 41 to 45 are fixed to the upper surfaces of the partition walls (cavity plates) 22 that partition the pressure chambers, so that the piezoelectric sheets 41 to 45 are deformed so as to be convex toward the pressure chambers. Therefore, the volume of the pressure chamber 10 decreases, the pressure of the ink rises, and the ink is ejected from the ink ejection port 8. Then, the individual electrodes 35a and 35b are connected to the common electrode 34.
When the potential is returned to the same as that of a and 34b, the piezoelectric sheets 41 to 45
Becomes the original shape and the volume of the pressure chamber 10 returns to the original volume, so that ink is sucked from the manifold 5 side.

As another driving method, the individual electrodes 35a and 35b are set to different potentials from the common electrodes 34a and 34b in advance, and the individual electrodes 35a and 3b are discharged every time a discharge request is made.
5b is once set to the same potential as the common electrodes 34a and 34b, and then the individual electrodes 35a and 35b are again set at a predetermined timing.
Can have a potential different from that of the common electrodes 34a and 34b. In this case, the piezoelectric sheets 41 to 45 return to their original shapes at the timing when the individual electrodes 35a and 35b and the common electrodes 34a and 34b have the same potential, so that the volume of the pressure chamber 10 is in the initial state (of both electrodes). Ink is sucked into the pressure chamber 10 from the manifold 5 side as compared with the case where the potential is different). After that, the individual electrodes 35a, 3
At a timing when 5b is set to a potential different from that of the common electrodes 34a and 34b, the piezoelectric sheets 41 to 45 are deformed so as to be convex toward the pressure chamber 10, and the pressure on the ink increases due to the decrease in the volume of the pressure chamber 10, Is discharged.

If the direction of the electric field applied to the piezoelectric sheets 41 to 45 and the polarization direction thereof are opposite to each other, the individual electrodes 35a and 35b and the common electrodes 34a and 34 are formed due to the piezoelectric lateral effect.
The active layers in the piezoelectric sheets 41 and 42 sandwiched by the line b and b tend to extend in the direction perpendicular to the polarization direction. Therefore, the piezoelectric sheets 41 to 45 are deformed so as to be concave toward the pressure chamber 10. Therefore, the volume of the pressure chamber 10 increases and ink is sucked from the manifold 5 side. Then, the individual electrode 35
If the potentials of a and 35b are restored, the piezoelectric sheets 41 to 45
Becomes the original flat plate shape, and the volume of the pressure chamber 10 returns to the original volume, so that ink is ejected from the ink ejection port 8.

Next, a method of manufacturing the ink jet head 1 according to this embodiment will be described.

To manufacture the ink jet head 1,
First, the flow path unit 4 and the actuator unit 21 are separately manufactured in parallel, and then both are bonded. In order to manufacture the flow path unit 4, etching is performed on each of the plates 22 to 30 constituting the flow path unit 4 by using the patterned photoresist as a mask, and then, as shown in FIGS.
An opening as shown in FIG. 4 is formed in each of the plates 22 to 30. After that, the nine plates 22 to 30 are superposed on each other with an adhesive interposed and bonded so that the ink flow path 32 is formed, and thus the flow path unit 4 is manufactured.

On the other hand, in order to manufacture the actuator unit 21, first, a conductive paste serving as the individual electrode 35b is pattern-printed on the green sheet of the ceramic material serving as the piezoelectric sheet 43. At the same time, a conductive paste serving as the common electrodes 34a and 34b is pattern-printed on the ceramic green sheets serving as the piezoelectric sheets 42 and 44. Then, the piezoelectric sheets 41 to 45
The laminated product obtained by stacking the five green sheets described below while aligning them using a jig is fired at a predetermined temperature. Then, the individual electrodes 35a are formed on the piezoelectric sheet 41 of the fired laminate. Individual electrode 3
For 5a, for example, a conductive film is entirely plated on the piezoelectric sheet 41 and unnecessary portions are removed by laser patterning, or the piezoelectric sheet 41 is electrically conductive using a mask having an opening at a portion corresponding to the individual electrode 35a. PVD membrane
It may be formed by vapor deposition such as (Physical Vapor Deposition). The production of the actuator unit 21 is completed by the steps up to here.

Next, the actuator unit 21 manufactured as described above is bonded to the flow path unit 4 with an adhesive so that the piezoelectric sheet 45 and the cavity plate 22 are in contact with each other. At this time, the both are bonded on the basis of the alignment marks formed on the surface of the cavity plate 22 of the flow path unit 4 and the surface of the piezoelectric sheet 41, respectively.

Then, the corresponding individual electrodes 3 which are vertically overlapped with each other.
A through hole is formed to connect 5a and the individual electrode 35b, and the through hole is filled with a conductive material. After that, in order to supply electric signals to the individual electrodes 35a and 35b and the common electrodes 34a and 34b, the FPC 13
The manufacturing of the inkjet head 1 is completed by pasting 6 onto the joining position corresponding to each electrode on the actuator unit 21 so as to be electrically joined by soldering, and further passing through predetermined steps.

As described above, the reason why only the individual electrode 35a is not fired together with the ceramic material forming the piezoelectric sheets 41 to 45 unlike the other electrodes is that the individual electrode 35a is exposed, and therefore the high temperature during firing is used. Easily evaporated by heating,
Other electrodes 34a, 34 coated with a ceramic material
This is because it is difficult to control the thickness as compared with b and 35b. However, the thickness of the other electrodes 34a, 34b, 35b also decreases to some extent during firing, so it is difficult to reduce the thickness in consideration of maintaining continuity after firing. On the other hand, since the individual electrode 35a is formed by the method as described above after firing, the other electrodes 34a, 34b, 3
It can be formed thinner than 5b. As described above, in the inkjet head 1, the displacement of the piezoelectric sheets 41 to 43 including the active layer is regulated by the individual electrode 35a by making the individual electrode 35a in the uppermost layer thinner than the other electrodes 34a, 34b, 35b. This makes it difficult to improve the efficiency of the actuator unit 21 (electrical efficiency and area efficiency).

The ink jet head 1 includes the piezoelectric sheets 41 to 43 including the active layer and the piezoelectric sheet 4 which is the inactive layer.
Since 4 and 45 are made of the same material, there is no need to replace the material, and it can be manufactured by a relatively simple manufacturing process. Therefore, it is expected that the manufacturing cost can be reduced. Further, the piezoelectric sheet 4 including an active layer
1 to 43 and the piezoelectric sheets 44 and 45, which are inactive layers, all have substantially the same thickness, so that the cost can be reduced by simplifying the manufacturing process. This is because it becomes possible to easily perform the thickness adjusting step when coating and laminating the ceramic material to be the piezoelectric sheet.

Further, in the ink jet head 1 according to the present embodiment, a plurality of actuator units 21 divided for each ink ejection area are arranged along the longitudinal direction in a state of being bonded to the flow path unit 4. . As a result, it becomes possible to perform alignment with the flow path unit 4 for each actuator unit 21 in which variation in dimensional accuracy and variation in positional accuracy of the individual electrodes 35a and 35b tend to occur due to being formed by sintering or the like. Each actuator unit 2 even if the head is elongated
1 is suppressed from increasing the amount of positional deviation between the flow path unit 4 and
Both can be accurately aligned. Therefore,
The positions of the individual electrodes 35a and 35b relatively far from the mark with respect to the pressure chamber 10 are less likely to be significantly displaced from the predetermined position, so that good ink ejection performance is obtained and the manufacturing yield of the inkjet head 1 is improved. Improve dramatically. On the other hand, unlike this, when the actuator unit 21 is formed as an elongated body similar to the flow path unit 4, the pressure chambers 10 in plan view when the actuator unit 21 and the flow path unit 4 are stacked.
The amount of deviation of the positions of the individual electrodes 35a, 35b from the predetermined position with respect to the mark increases as the distance from the mark increases, and the ink discharge performance in the pressure chamber 10 relatively far from the mark deteriorates, and the ink discharge in the inkjet head 1 is deteriorated. The performance uniformity is lost.

Further, according to the ink jet head 1 configured as described above, the piezoelectric sheets 41 to 43 are sandwiched between the common electrodes 34a and 34b and the individual electrodes 35a and 35b, so that the pressure chamber 10 can be easily provided by the piezoelectric effect. The volume can be changed. Further, since the piezoelectric sheets 41 to 43 including the active layer are continuous flat plate layers, they can be easily manufactured.

Further, the ink jet head 1 has a unimorph structure actuator unit in which the piezoelectric sheets 44 and 45 close to the pressure chamber 10 are inactive layers, and the piezoelectric sheets 41 to 43 apart from the pressure chamber 10 are layers including active layers. 21
have. Therefore, due to the piezoelectric lateral effect, the pressure chamber 10
The volume change amount can be increased, and the voltage applied to the individual electrodes 35a and 35b can be reduced as compared with an inkjet head in which the pressure chamber 10 side is a layer including an active layer and the opposite side is a non-active layer. And / or the pressure chamber 10 can be highly integrated. By reducing the applied voltage, the driver for driving the individual electrodes 35a and 35b can be downsized, and the cost can be suppressed.
It is possible to discharge a sufficient amount of ink even when the size of the head 1 can be reduced and the degree of integration of the head 1 is increased, and the head 1 can be downsized and print dots can be arranged at a high density.

Further, in the ink jet head 1, each actuator unit 21 has a substantially trapezoidal shape, and the parallel opposing sides of each actuator unit 21 are along the longitudinal direction of the flow path unit 4 and adjacent to each other. The plurality of actuator units 21 are arranged in two rows in a zigzag manner such that the oblique sides of are overlapped with each other in the width direction of the flow path unit 4. In this way, since the oblique sides of the adjacent actuator units 21 overlap each other, when the inkjet head 1 relatively moves in the width direction with respect to the print medium,
The pressure chambers 10 existing along the width direction of the flow path unit 4 can complement each other, and high-resolution printing can be realized, and the ink jet head 1 having a very narrow width can be obtained.

Further, in the flow path unit 4, since a large number of pressure chambers 10 adjacent to each other are arranged in a matrix, the large number of pressure chambers 10 are arranged in a relatively small size region.
Can be arranged in high density.

In the ink jet head 1 described above, a plurality of trapezoidal actuator units are arranged in two rows in a zigzag pattern. However, the actuator units do not necessarily have to be trapezoidal, and the plurality of actuator units may be arranged in a flow path unit. They may be arranged in a single row along the longitudinal direction of the. Alternatively, the actuator units may be arranged in three or more rows in a staggered pattern.

Next, a second embodiment of the present invention will be described. FIG. 11 is a plan view of the head body of the inkjet head according to the present embodiment. In the inkjet head and the inkjet printer according to the present embodiment, parts other than the head body are similar to those in the above-described first embodiment, and therefore detailed description thereof will be omitted here.

As shown in FIG. 11, the head main body 201 of the ink jet head according to this embodiment is formed in a rectangular plane shape extending in one direction (main scanning direction). The head body 201 includes a number of pressure chambers 210, which will be described later.
Flow path unit 204 in which ink discharge ports 208 are formed
Two parallelogram-shaped actuator units 221 (the one on the right side is indicated by reference numeral 221a and the one on the left side is indicated by reference numeral 221b in FIG. 11) are adhered side by side on the upper surface thereof. . Each actuator unit 221 is arranged so that one side B thereof extends along the longitudinal direction of the head body 201. Adjacent actuator units 221 are arranged in a state in which they are aligned in the width direction (widthwise direction) of the head body 201, with their hypotenuses C being close to each other. An ink supply port 202 is opened on the upper surface of the flow path unit 204, and the ink supply port 202 is connected to an ink supply source via a path not shown.

As shown in FIG. 12, which is a view of the head main body 201 as viewed from the side opposite to FIG. 11 (printing surface side), the actuator unit 22 is provided on the lower surface of the flow path unit 204.
Two parallelogram ink ejection regions R1 are provided corresponding to the region where 1 is arranged. A large number of ink ejection ports 208 having a small diameter are arranged on the surface of the ink ejection region R1.

In the present embodiment, the case of performing monochrome printing is shown, and one color (for example, black) ink is supplied to the ink supply port 202. It should be noted that the configuration for performing multi-color printing is the head main body 201 of the number of colors in the flow path unit width direction (for example, if there are four colors of yellow, cyan, magenta, and black, four head main bodies 201). ) Are arranged side by side, and each head main body 201 performs printing while supplying inks of different colors.

A cross-sectional view showing the internal structure of the flow path unit 204 is shown in FIG. As shown in FIG. 13, a manifold channel 205 is formed inside the channel unit 204, and this manifold channel 205 is used as the ink supply port 2.
As a result of being connected to the ink supply source via 02, the manifold channel 205 is always filled with ink. In addition,
It is desirable that the ink supply port 202 be provided with a filter for capturing dust and the like contained in the ink.

The manifold flow path 205 is formed over most of the flow path unit 204 so as to extend over the two ink ejection regions R1. In the manifold flow channel 205, a large number of elongated parallelogram-shaped islands 205a are formed at equal intervals in a portion corresponding to the ink ejection region R1 so that their longitudinal directions are aligned with the longitudinal direction of the flow channel unit 204. Has been done. In this configuration, the ink supplied from the ink supply port 202 passes between the adjacent island portions 205a inside the manifold flow path 205, and the flow path unit 2 is provided in each ink ejection region R1.
It is distributed to a pressure chamber 210, which will be described later, formed in 04.

Each ink ejection port 208 is a tapered nozzle as shown in FIG. 15, and communicates with the manifold flow channel 205 via a pressure chamber 210 and an aperture 212 whose planar shape is a substantially parallelogram. There is. With this configuration, the ink flows from the manifold channel 205 to the aperture 2
It is supplied to the pressure chamber 210 via 12. Then, by driving an actuator unit 221, which will be described later, ejection energy is applied to the ink in the pressure chamber 210 to eject the ink from the ink ejection port 208.

FIG. 14 shows the detailed structure of the area indicated by the symbol Q in FIG. As is clear from FIG. 14, the ink ejection region R1 on the upper surface of the flow path unit 204 is
In the region corresponding to, a large number of pressure chambers 210 are arranged in a matrix while being adjacent to each other. In addition,
Since the pressure chambers 210 and the apertures 212 are provided at different heights as shown in FIG.
It can be arranged as shown in FIG. 14 so as to overlap 0. As a result, a high-density arrangement of the pressure chambers 210 can be realized,
This contributes to downsizing of the head body 201 and higher resolution of the formed image.

FIG. 15 shows a specific structure of the path from the manifold flow path 205 to the ink discharge port 208. As shown in this figure, the flow path unit 204 includes a cavity plate 222, a base plate 223, an aperture plate 224, and a base plate 223. Supply plate 225, manifold plates 226, 227, 228, cover plate 22
9, a total of 9 sheet materials of the nozzle plate 230 are laminated. Then, the above-mentioned actuator unit 221 is adhered to the upper surface of the flow path unit 204,
The head body 201 is configured. The detailed configuration of the actuator unit 221 will be described later.

The cavity plate 222 is provided with parallelogram-shaped openings to form the above-mentioned pressure chamber 210, while the nozzle plate 230 is provided with the tapered ink ejection port 2.
08 is formed by pressing. Both plates 22
Communication holes 251 penetrate through the plates 223 to 229 sandwiched between 2, 230, and the pressure chamber 210 and the ink ejection port 208 are connected through these communication holes 251. The aperture plate 224 is provided with an aperture 212 having a long hole shape, and one end of this aperture 212 has a communication hole 252 formed in the base plate 223.
Is connected to the end of the pressure chamber 210 (the end opposite to the side connected to the ink ejection port 208). The aperture 212 plays a role of appropriately adjusting the amount of ink supplied to the pressure chamber 210 and preventing the amount of ink ejected from the ink ejection port 208 from being excessive or excessive. A communication hole 253 is opened in the supply plate 225 to connect the other end of the aperture 212 and the manifold channel 205.

All of the nine plates 222 to 230 constituting the flow path unit 204 are made of metal, and the pressure chamber 210, the aperture 212 and the communication holes 251, 25 are formed.
2, 253 are formed by subjecting each metal plate to selective etching using a mask pattern. Then, the nine plates 222 to 230 are laminated and adhered after being aligned with each other so as to form a flow path as shown in FIG.

As shown in FIG. 16, the actuator unit 221 includes five piezoelectric sheets 241 to 245 each formed to have the same thickness of about 15 μm. These piezoelectric sheets 241 to 245 are continuous flat plate layers, and one actuator unit 221 is
The head main body 201 is arranged over a number of pressure chambers 210 formed in one ink ejection region R1. By doing so, it is possible to arrange the individual electrodes 235a and 235b in the actuator unit 221 at high density. As a material for the piezoelectric sheets 241-245, lead zirconate titanate (PZT) having ferroelectricity is used.
A ceramic material of the series is used.

Between the piezoelectric sheets 241 and 242 of the first layer and the second layer, which are counted from the top, a common electrode 234a having a thickness of about 2 μm is formed on almost the entire surface of the sheet.
Similarly, a common electrode 234b having a thickness of about 2 μm is also interposed between the third-layer and fourth-layer piezoelectric sheets 243 and 244. The upper surface of the piezoelectric sheet 241 of the first layer has a thickness of 1 μm.
m individual electrodes 235a are formed for each pressure chamber 210. As shown in FIG. 14, the planar shape of the individual electrode 235a is a shape in which the shape of the pressure chamber 210 is slightly reduced while maintaining a similar shape, and the center position of the individual electrode 235a substantially coincides with the center position of the pressure chamber 210. It is arranged. Further, the second and third layer piezoelectric sheets 242, 24
Between 3 as well, an individual electrode 235b having a thickness of about 2 μm and formed similarly to the individual electrode 235a is arranged. The portion where these individual electrodes 235a and 35b are arranged corresponds to the pressure generating portion A that applies pressure to the ink in the pressure chamber 210. In addition, the fourth and fifth layers of the piezoelectric sheet 2
44, 245 and the fifth-layer piezoelectric sheet 245
No electrodes are arranged on the lower surface of the. These electrodes 23
4a, 234b, 235a and 235b are made of a metal material such as Ag-Pd.

Since the common electrodes 234a and 234b are grounded in a region (not shown), the common electrodes 234a and 234b
234b is equally kept at the ground potential in the regions corresponding to all the pressure chambers 210. Individual electrode 23
5a and 235b are provided with individual electrodes 235a and 235 so that the potentials can be independently controlled for each pressure chamber 210.
Each of the 35b is connected to an appropriate driver IC via an independent lead wire.

In the head body 201, the piezoelectric sheet 2
The polarization directions of 41 to 245 are in the thickness direction. That is, the actuator unit 221 includes three piezoelectric sheets 241 to 2 on the upper side (the side far from the pressure chamber 210).
43 is a layer including an active layer, and the two lower piezoelectric sheets 244 and 245 are inactive layers (so-called unimorph type).

In this structure, the individual electrodes 235a, 2
When 35b is set to a predetermined potential of + or −, for example, when the electric field and the polarization are in the same direction, the portion sandwiched between the electrodes of the piezoelectric sheets 241 to 243 (active layer, that is, pressure generating portion) is
Shrinks in the direction perpendicular to the polarization direction. On the other hand, since the piezoelectric sheets 244 and 245 of the inactive layer are not affected by the electric field, they do not contract spontaneously. As a result, the upper piezoelectric sheets 241-
243 and the lower piezoelectric sheets 244 and 245 have different strains in the polarization direction.
Deformation occurs in which the whole is convex on the inactive side (unimorph deformation). Since the lower surface of the lowermost piezoelectric sheet 245 is fixed to the upper surface of the partition wall that separates the plurality of pressure chambers 210 from each other, the piezoelectric sheets 241 to 245 have the pressure generating portions A of the piezoelectric sheets 241 to 245 convex toward the pressure chamber 210 side. It deforms and reduces the volume of the pressure chamber 210. As a result, the ink pressure rises, and the ink is ejected from the ink ejection port 208. After that, when the application of the drive voltage to the individual electrodes 235a and 235b is stopped, the piezoelectric sheets 241 to 245 return to their original shapes, the volume of the pressure chamber 210 returns to the original shape, and ink is sucked from the manifold channel 205. .

Next, the two actuator units 22
The shape of 1a and the arrangement of the individual electrodes 235a and 235b (in other words, the arrangement of the pressure generating portion A) will be described. FIG. 17 is a diagram showing the shape of the actuator unit 221a and the arrangement of the pressure generating portions. FIG. 18 is a diagram showing the relationship between the joint portion between the actuator unit 221a and the actuator unit 221b and the pressure generating portion in the additional region.

As described above, the head main body 201 has the two actuator units 221a and 221b, but the shape and the arrangement of the pressure generating portion A are the same for the two actuator units 221a and 221b.

As shown in FIGS. 11 and 17, the actuator unit 221a is formed in a parallelogram shape, one side B of which is parallel to the longitudinal direction of the flow path unit 204,
The other side C is arranged in the channel unit 204 such that the other side C is oblique to the longitudinal direction of the channel unit 204. Then, as shown in FIG. 17, the actuator unit 221
Two regions P1 and P2, which are divided in the width direction of the flow path unit by a straight line along the longitudinal direction of the flow path unit 204, that is, adjacent to each other in the width direction of the flow path unit 204, are set in a.

Of these, in the basic region P1, a large number of pressure generating portions A1 are adjacent to each other while the flow passage unit 2
They are arranged in a matrix in the direction along the longitudinal direction of 04 and the direction along the other side C of the parallelogram.

In the remaining area (additional area P2) excluding the basic area P1, the pressure generating portions A2 are adjacent to each other only in the vicinity of the parallelogram-shaped acute angle portion D closer to the actuator unit 221b. However, they are arranged in a matrix.

When the two actuator units 221a and 221b having such a configuration are arranged side by side in the longitudinal direction of the flow path unit 204 as shown in FIG. 11, the actuator unit 221a and the actuator unit 221b are arranged as shown in FIG. The pressure generating portion of the additional area P2 provided in the actuator unit 221a at a position corresponding to the area (the area G shown by hatching in FIG. 18) where the pressure generating portion A cannot be arranged in the basic area P1 because it is located at the joint of A2 will be located. That is,
The pressure generating portion A2 of the additional area P2 is a gap portion G between the pressure generating portion A1 of the basic area P1 provided in the actuator unit 221a and the pressure generating portion A1 of the basic area P1 provided in the adjacent actuator unit 221b. Therefore, it is possible to provide the head main body 201 which can print without interruption in the entire longitudinal direction of the flow path unit without separately disposing an actuator unit for ejecting ink from the gap portion G. Has become.

In other words, the actuator unit 2
Since the pressure generating portion cannot be arranged in the region (region G) near the joint between 21a and the actuator unit 221b, neither the pressure chamber 210 nor the ink ejection port 208 can be arranged in that region. Therefore,
If the pressure generating portion A2 is not arranged in the additional area P2 provided in the actuator unit 221a, the portion corresponding to the gap G cannot be printed, and ink cannot be ejected at the joint portion between the actuator units 221a and 221b. There are possible parts. However, this area G
Since the pressure generating portion A2 is arranged in the additional area P2 provided in the actuator unit 221a at the overlapping portion in the flow path unit width direction, there is no portion where ink cannot be ejected. As a result, it is possible to form a continuous image on the paper.

As described above, in the present embodiment, the actuator unit 221 is provided with a plurality of rows in which a large number of pressure generating portions A1 and A2 are arranged in the longitudinal direction of the flow path unit 204. The length of this row along the longitudinal direction of the flow path unit 204 is long in the basic region P1 and short in the additional region P2. When considering the number of rows along the width direction of the flow path unit 204, the number of rows in the additional region P2 is within the length of the corresponding area G in the width direction of the flow path unit 204. It has the same number of columns that would exist in. Therefore, when an imaginary straight line extending in the width direction of the flow path unit 204 is drawn, the imaginary straight line in the number of rows that intersect in the region where the adjacent actuator units 221a and 221b overlap each other and in the region that does not overlap each other. It is the same as the number of intersecting columns.

Since the above-described structure can be achieved only by arranging two actuator units 221a and 221b having the same structure, the parts structure is simplified and the cost required for designing and manufacturing the actuator units 221a and 221b is reduced. -Man-hours can be reduced.

The arrangement of the pressure generating portion A in the actuator unit 221 described in the present embodiment is an example, and the actuator unit 255 shown in FIG. 19 may be used. FIG. 19 is a diagram showing another example of the arrangement of the pressure generators of the actuator unit. 20 is a diagram showing the relationship between the joint portion of the actuator unit and the pressure generating portion in the additional region in the arrangement of FIG.

The actuator unit 25 shown in FIG.
5a has a region P1 divided into three in the width direction of the flow path unit.
1, P12 and P13 are set. Then, the central area P11 in the width direction of the flow path unit is used as a basic area, and the remaining area P
12 and P13 are additional areas.

As in the case of the arrangement shown in FIG. 17, in the basic region P11, a number of pressure generating portions A11 are adjacent to each other, along the longitudinal direction of the flow path unit, and the other side C of the parallelogram. Are arranged in a matrix along the direction. On the other hand, in the additional region P12, the pressure generating portions A12 are arranged in a matrix form adjacent to each other in the vicinity of the parallelepiped acute angle portion D nearer to the actuator unit 255b. In the additional region P13, the pressure generating portions A13 are arranged in a matrix form adjacent to each other in the vicinity of the parallelogram-shaped acute angle portion D farther from the actuator unit 255b.

Therefore, as shown in FIG. 20, the pressure generating portion A12 of the additional area P12 of the actuator unit 255a and the additional area P of the actuator unit 255b.
The pressure generating unit A13 of 13 is connected to the actuator unit 255.
The pressure generating portion A11 of the basic region P11 provided in a and the pressure generating portion A11 of the basic region P11 provided in the adjacent actuator unit 255b are arranged corresponding to the gap G. Therefore, it is possible to provide the head main body 201 capable of ejecting the ink without a break in the entire longitudinal direction of the flow path unit.

Besides, according to this embodiment, the same advantages as those of the above-described first embodiment can be obtained. Specifically, the two actuator units 255
Since a and 255b are arranged along the longitudinal direction of the flow path unit 204, the actuator units 255a and 255b can be formed even if the flow path unit 204 is elongated.
And the alignment accuracy between the flow path unit 204 and
Good ink ejection performance is obtained, and the manufacturing yield of the inkjet head 201 is dramatically improved. In addition, the piezoelectric sheets 241-243 are connected to the common electrodes 234a, 2
By sandwiching between 34b and the individual electrodes 235a and 235b, the volume of the pressure chamber 210 can be easily changed by the piezoelectric effect. Moreover, since the piezoelectric sheets 241 to 243 including the active layer are continuous flat plate layers, they can be easily manufactured. Moreover, the piezoelectric sheets 244 and 245 close to the pressure chamber 210 are used as inactive layers, and the pressure chamber 210
Actuator unit 221 having a unimorph structure in which the piezoelectric sheets 241 to 243 separated from each other are used as layers including an active layer
Since the piezoelectric lateral effect is provided, the volume change amount of the pressure chamber 210 can be increased, and the individual electrode 235
It is possible to reduce the voltage applied to a and 235b and / or increase the integration of the pressure chamber 210. Further, in the flow path unit 204, since a large number of pressure chambers 210 adjacent to each other are arranged in a matrix, it is possible to arrange a large number of pressure chambers 210 in a relatively small size with high density.

In this embodiment, two actuator units are arranged side by side, but it is needless to say that the present invention can be applied to a structure in which three or more actuator units are arranged. It becomes possible to manufacture a long inkjet head by arranging a large number of them, and this inkjet head is advantageous in that it can print on a large size paper at high speed.

21 (a) and 21 (b), four actuator units 261 configured similarly to the actuator unit 221 or the actuator unit 255 (reference numeral 26 from the right in these figures respectively)
1a, 261b, 261c, 261d)
Head bodies 271 and 272 according to a modification in which the inks are aligned and bonded in a straight line to a flow path unit 274 having ink supply ports 273 near both ends are shown. The actuator unit 261 is the actuator unit 2
21 or the actuator unit 255, the flow path unit as shown in FIG.
Since even long channel units as shown in 1 (a) can be commonly used for channel units having different lengths, the versatility as a component is high and the manufacturing cost can be reduced. is there.

In the head main bodies 201 and 271 shown in FIGS. 11 and 21 (a), the actuator units are arranged in a straight line and arranged in the flow path unit in a state aligned in the width direction of the flow path unit. There is. However, a plurality of actuator units 261a and 261 are provided, for example, as in the head main body 272 shown in FIG.
b, 261c and 261d may be arranged in a staggered pattern. However, from the viewpoint of downsizing of the inkjet head, the configuration shown in FIG. 11 or FIG. 21 (a) in which a plurality of actuator units are arranged neatly in the width direction of the flow path unit and arranged linearly in the longitudinal direction of the flow path unit. Is desirable. In particular, since the configuration of FIGS. 11 and 21 (a) can reduce the width of the inkjet head, a plurality of inkjet heads are arranged side by side in the width direction and inks of different colors are supplied to perform multicolor printing. At this time, it is advantageous in that a plurality of inkjet heads can be arranged in a compact space, and color misregistration of an image can be reduced even when the paper is skewed during printing.

Next, a third embodiment of the present invention will be described. 22 is a plan view of the head body of the inkjet head according to the present embodiment. In the inkjet head and the inkjet printer according to the present embodiment, the parts other than the head body are the same as those in the first embodiment.
Since it is similar to the embodiment described above, detailed description thereof will be omitted here.

As shown in FIG. 22, the head body 301 of the ink jet head according to this embodiment has a rectangular plane shape extending in one direction. The head main body 301 has a flow path unit 304 in which a large number of pressure chambers 310 and ink outlets 308 to be described later are formed.
1 (reference numerals 321a and 321, respectively, from the right in FIG. 22)
1b, 321c, 321d) are arranged in a zigzag in two rows and bonded. Each actuator unit 321 has its parallel facing sides (upper side and lower side).
Are arranged along the longitudinal direction of the head body 301. The adjacent actuator units 321 are arranged such that their oblique sides are close to each other and an overlapping portion is formed in the flow channel unit width direction.

As shown in FIG. 23, which is a view of the flow path unit 304 seen from the opposite side (printing surface side) from FIG. 22, the lower surface of the flow path unit 304 has a region where the actuator unit 321 is arranged. Correspondingly, four hexagonal ink ejection regions R2 are set. This ink ejection area R2
A large number of ink ejection ports 308 having a small diameter are arranged on the surface of the. The base block 3 is provided on the upper surface of the head body 301.
02 is arranged, and inside the base block 302,
A pair of ink reservoirs 303 formed in a slender shape along the longitudinal direction of the head body 301 are arranged. One end of each ink reservoir 303 has an opening 303a formed on the upper surface of the base block 302, and as a result of this opening 303a being connected to an ink tank (not shown), the ink reservoir 303 is always filled with ink.

A sectional view showing the internal structure of the flow path unit 304 is shown in FIG. As shown in FIG. 24, manifold channels 305 as a plurality of ink supply sources are formed inside the channel unit 304. Each manifold channel 305 corresponds to the channel unit 3
The ink reservoir 303 communicates with an opening 305a formed on the upper surface of the ink container 04. In addition, it is desirable to provide a filter for capturing the dust contained in the ink in the opening 305a.

The manifold channel 305 is branched from the opening 305a in a branched shape, and has a large number of pressure chambers 31 to be described later.
Ink is supplied to 0. One of the manifold flow channels 305 is provided corresponding to one side of one of the hexagonal ink discharge regions R2 shown in FIG. 23 when it is equally bisected above and below the paper surface of FIG. .. Eight manifold channels 305 are provided, and the shape of each channel is determined so that ink is distributed and supplied to all the pressure chambers 310 included in the corresponding regions.

The ink discharge ports 308 located in the half area on the one side in the width direction of the flow path unit are all connected to the ink reservoir 303 on one side out of a pair arranged via the manifold flow path 305. There is. The ink ejection port 308 located in the other half of the width direction of the inkjet head communicates with the ink reservoir 303 on the other side. In this way, the manifold channel 305 and the opening 305a
By configuring the ink pool 303 and the ink pool 303, (1) a mode in which the same color ink is supplied to the pair of ink pools 303 to perform high-resolution printing of a single color, (2) the pair of ink pools 303 have different colors It is possible to adopt both printing forms, that is, a form in which two colors are printed by one head main body 301 by supplying the above ink, and it has a highly versatile configuration.

Each ink ejection port 308 is a tapered nozzle as shown in FIG. 26, and communicates with the manifold channel 305 via the pressure chamber 310 and the aperture 312, each of which has a substantially rhombic plan shape. . With this configuration, ink reaches the manifold channel 305 from the ink tank via the ink reservoir 303, and the manifold channel 3
The gas is supplied to the pressure chamber 310 from 05 through the aperture 312. Then, an actuator unit 321 described later
Is driven to apply the ejection energy to the ink in the pressure chamber 310 to eject the ink from the ink ejection port 308.

FIG. 25 shows the fine structure of the area indicated by the symbol E in FIG. As is clear from FIG. 25, the ink discharge region R2 on the upper surface of the flow path unit 304
In a region corresponding to, a large number of pressure chambers 310 are arranged in a matrix while being adjacent to each other. In addition,
As shown in FIG. 26, the pressure chamber 310 and the aperture 312 are
Are arranged at different heights, the aperture 312 connected to one pressure chamber 310 is connected to the other pressure chamber 310.
Can be arranged to overlap. As a result, a high density arrangement of the pressure chambers 310 can be realized, which contributes to downsizing of the head body 301 and higher resolution of the formed image.

FIG. 26 shows a specific structure of the path from the manifold flow channel 305 to the ink discharge port 308. As shown in this figure, the flow path unit 304 includes a total of nine sheet materials including a cavity plate 322, a base plate 323, an aperture plate 324, a supply plate 325, manifold plates 326, 327, 328, a cover plate 329, and a nozzle plate 330. It is configured by stacking. And this channel unit 3
An actuator unit 321 is bonded to the upper surface of 04 to form the head body 301. The detailed configuration of the actuator unit 321 will be described later.

The cavity plate 322 is provided with a rhombic opening to form a pressure chamber 310, while the nozzle plate 330 has a tapered ink ejection port 308 formed by pressing. A communication hole 351 penetrates through the plates 323 to 329 sandwiched between the plates 322 and 330, and the pressure chamber 310 and the ink ejection port 308 are connected through this communication hole 351. The aperture plate 324 is provided with a long-hole-shaped aperture 312, and one end of the aperture 312 has a base plate 3
It is connected to the end of the pressure chamber 310 (the end on the side opposite to the side connected to the ink ejection port 308) via the communication hole 352 formed in the reference numeral 23. The aperture 312 is the pressure chamber 3
The amount of ink supplied to 10 is appropriately adjusted to play a role of preventing the amount of ink ejected from the ink ejection port 308 from being excessive or excessive. A communication hole 353 is opened in the supply plate 325, and the other end of the aperture 312 and the manifold channel 305 are provided through this communication hole 353.
And are connected.

All of the nine plates 22 to 30 constituting the flow path unit 304 are made of metal, and the pressure chamber 310, the aperture 312, and the communication holes 351 and 35 described above are used.
2, 353 are formed by subjecting each metal plate to selective etching using a mask pattern. Then, the nine plates 22 to 30 are aligned with each other and then stacked and adhered so as to form a flow path as shown in FIG.

Next, the structure of the actuator unit 321 will be described. As shown in FIG. 27, the actuator unit 321 has five piezoelectric sheets 341 to 341 each formed to have the same thickness of about 15 μm.
It is equipped with 45. These piezoelectric sheets 341 to 45 are continuous flat plate layers, and one actuator unit 321
Are arranged over a large number of pressure chambers 310 formed in one ink ejection region R2 of the head body 301. By doing so, the individual electrodes 335a and 335b can be arranged at high density. Piezoelectric sheet 341-
As the material of 345, a lead zirconate titanate (PZT) -based ceramic material having ferroelectricity is used.

A common electrode 334a having a thickness of about 2 μm formed on the entire surface of the sheet is interposed between the piezoelectric sheets 341 and 342 of the first layer and the second layer counted from the top. Similarly, a common electrode 334b having a thickness of about 2 μm is interposed between the third-layer and fourth-layer piezoelectric sheets 343 and 344. The upper surface of the first-layer piezoelectric sheet 341 has a thickness of 1 μm.
The individual electrodes 335 a of a certain degree are formed for each pressure chamber 310. As shown in FIG. 25, the planar shape of the individual electrode 335a is a shape in which the shape of the pressure chamber 310 is slightly reduced while maintaining a similar shape, and the center position thereof substantially coincides with the center position of the pressure chamber 310. It is arranged.
Further, between the second-layer and third-layer piezoelectric sheets 342 and 343, a thickness of 2 μ is formed in the same manner as the individual electrode 335a.
m individual electrodes 335b are arranged. No electrodes are arranged between the fourth-layer and fifth-layer piezoelectric sheets 344 and 345 and on the lower surface of the fifth-layer piezoelectric sheet 345. These electrodes 34a, 34b, 35a, 3
5b is made of a metal material such as Ag-Pd.

Since the common electrodes 334a and 334b are grounded in a region (not shown), the common electrodes 334a and
334b is equally kept at the ground potential in the regions corresponding to all the pressure chambers 310. Individual electrode 33
The individual electrodes 335a and 335b are provided so that the potentials can be independently controlled for each pressure chamber 310.
Each of the 35b is connected to an appropriate driver IC (not shown) via an independent lead wire.

In the head body 301, the piezoelectric sheet 3
The polarization directions of 41 to 345 are in the thickness direction. That is, the actuator unit 321 has three piezoelectric sheets 341 to 341 on the upper side (the side far from the pressure chamber 310).
43 is a layer including an active layer, and two piezoelectric sheets 344 and 345 on the lower side (a side close to the pressure chamber 310) are inactive layers, which is a so-called unimorph type structure.

In this structure, the individual electrodes 335a, 3
If 35b is set to a predetermined potential of + or −, for example, if the electric field and the polarization are in the same direction, the portion sandwiched between the electrodes of the piezoelectric sheets 341 to 343 (active layer, that is, pressure generating portion) is
Shrinks in the direction perpendicular to the polarization direction. On the other hand, since the piezoelectric sheets 344 and 345 of the inactive layer are not affected by the electric field, they do not contract spontaneously. As a result, the upper piezoelectric sheets 341 to 341
343 and the lower piezoelectric sheets 344 and 345 have a difference in strain in the direction perpendicular to the polarization direction, and the piezoelectric sheet 3
The entire 41 to 345 are deformed so as to be convex on the non-active side (unimorph deformation). Since the lower surface of the lowermost piezoelectric sheet 345 is fixed to the upper surface of the partition wall that separates the plurality of pressure chambers 310, the piezoelectric sheets 341 to 345 form the pressure chambers 3.
The pressure chamber 310 is deformed in a convex shape toward the 10 side to reduce the volume of the pressure chamber 310. As a result, the ink pressure rises, and ink is ejected from the ink ejection port 308. After that, the individual electrode 3
If the application of the drive voltage to 35a and 335b is stopped,
The piezoelectric sheets 341 to 345 return to their original shapes, and the pressure chamber 3
The volume of 10 returns to the original volume, and the ink is supplied to the manifold channel 3
Inhale from 05.

In order to manufacture the actuator unit 321, first, green sheets of ceramic material to be the piezoelectric sheets 341 to 345 are laminated and fired. At that time, the individual electrodes 335b and the common electrodes 334a, 33 are provided on the green sheets of the respective ceramic materials as needed.
The metal material to be 4b is pattern-printed. After that, a metal material to be the individual electrodes 335a is entirely plated on the piezoelectric sheet 341 of the first layer, and then unnecessary portions are removed by laser patterning, or the individual electrodes 33 are formed.
A metal material to be the individual electrodes 335a is vapor-deposited on the piezoelectric sheet 341 using a mask having an opening corresponding to 5a.

The actuator unit 321 manufactured in this manner has a very brittle property because it is made of ceramic. In particular, the corners of the actuator unit 321 are very liable to be chipped, so extremely careful handling is required so that the corners do not come into contact with other parts during manufacturing and assembly.

However, the actuator unit 3
As shown in FIG. 28A, which is a plan view of FIG. 21, in the inkjet head according to the present embodiment, the actuator unit 321 has a substantially regular hexagonal outline shape, and the six straight line portions of the outline shape are included. (Side) L1
All of L6 to L6 are approximately 1 with respect to the adjacent straight line portion L.
They are connected at 20 °. As a result, the six corners θ1 to θ6 of the actuator unit 321 (where the two straight line portions L adjacent to each other intersect) are not acute angles, so that it is difficult to chip and the actuator is an expensive precision component. The unit 321 is less likely to be broken during the manufacturing process, which contributes to a reduction in manufacturing cost.

The above effects are not achieved only by the configuration in which all the corners θ1 to θ6 are 120 °. If the angle of a certain corner θn is 90 ° (right angle) or more,
The effect of making it difficult for the corners θn to be chipped is obtained. Therefore, in order to make a structure in which chipping is unlikely to occur at all six corner portions θ1 to θ6, all six straight line portions L1 to L6 are connected to the adjacent straight line portion L at a right angle or an obtuse angle. Is sufficient (angle θ1 ~
It is sufficient if the minimum value of θ6 is 90 ° or more), and the hexagonal contour shape can be freely deformed as long as this condition is satisfied. As an example, FIG. 28B shows an actuator unit 35 having a contour shape that satisfies the above conditions.
5 is shown.

Besides, according to this embodiment, the same advantages as those of the above-described first embodiment can be obtained. Specifically, four actuator units 321
Are arranged along the longitudinal direction of the flow path unit 304, the alignment accuracy between the actuator unit 321 and the flow path unit 304 is high even if the flow path unit 304 is elongated, and good ink ejection is achieved. The performance is obtained, and the manufacturing yield of the inkjet head 301 is dramatically improved. In addition, the piezoelectric sheets 341 to 341
43 to the common electrodes 334a and 334b and the individual electrode 335.
By sandwiching it with a and 335b, the volume of the pressure chamber 310 can be easily changed by the piezoelectric effect. Moreover, since the piezoelectric sheets 341 to 343 including the active layer are continuous flat plate layers, they can be easily manufactured. Moreover, the piezoelectric sheets 344, 3 close to the pressure chamber 310
Since the actuator unit 321 has a unimorph structure in which 45 is an inactive layer and the piezoelectric sheets 341 to 343 separated from the pressure chamber 310 are layers including the active layer,
Due to the piezoelectric lateral effect, the volume change amount of the pressure chamber 310 can be increased, and the voltage applied to the individual electrodes 335a and 335b can be lowered and / or the pressure chamber 310 can be highly integrated. . Furthermore, the flow path unit 304
Since a large number of pressure chambers 310 adjacent to each other are arranged in a matrix in (1), it is possible to arrange a large number of pressure chambers 210 in a relatively small size with high density.

Further, in the present invention, the contour shape of the actuator unit is not limited to the hexagon.
That is, the number of straight line portions L is not limited to six, and may be five, seven, eight, or more straight line portions. Hereinafter, modifications of the contour shape of the actuator unit will be described with reference to FIGS. 29 to 31. In the following modifications, the same members as those in the above-described third embodiment are designated by the same reference numerals.

FIG. 29 (a) is a plan view of the head main body when the actuator unit is a heptagon. Figure 2
9B is a plan view of the actuator unit included in the head main body shown in FIG. As can be seen from these drawings, in this modification, the head body 361 is
Is an actuator unit 362 (reference numerals 362a, 362b, 362c, 362 from the right in FIG. 29).
Other than that (represented by d), the head body 301 has the same configuration as that of the head body 301 in the third embodiment.

As can be seen from FIG. 29 (b), the actuator unit 362 has a contour shape in which one of the corner portions of the hexagon of the above-described embodiment is linearly cut off. As a result, there are seven straight line portions L (L8 to L1
4), the angle of the corner is about 120 ° for θ8 to θ12, θ
13 and θ14 are about 150 °.

FIG. 30A is a plan view of the head main body when the actuator unit is octagonal. Figure 3
0 (b) is a plan view of the actuator unit included in the head body shown in FIG. 30 (a). As can be seen from these drawings, the head main body 371 in this modified example.
Is an actuator unit 372 (reference numeral 372a, 372b, 372c, 372 respectively from the right in FIG. 30).
Other than that (represented by d), the head body 301 has the same configuration as that of the head body 301 in the third embodiment.

As can be seen from FIG. 30 (b), the actuator unit 372 has a contour shape in which two of the corner portions of the hexagon of the above-described embodiment are linearly cut off. As a result, there are eight straight lines L (L15 to L
22), the angle of the corner is about 120 ° for θ15, θ16, θ19, and θ20, and about 15 for θ17, θ18, θ21, and θ22.
It is 0 °. With the configurations of the two modified examples described above,
Compared with the hexagonal actuator unit 321, the corner portion of the cut-off portion is as large as 150 °, and the chipping of the corner portion is more difficult to occur.

FIG. 31 (a) is a plan view of the head main body in the case where two of the connecting portions of the linear portions L adjacent to each other of the actuator unit are arcuate portions F in the third embodiment. . FIG. 31 (b) shows FIG.
FIG. 6 is a plan view of an actuator unit included in the head main body shown in FIG. As you can see from these drawings,
In this modification, the head main body 381 has an actuator unit 382 (reference numeral 38 from the right in FIG. 31).
2a, 382b, 382c, 382d)
Except for this, the head main body 301 has the same configuration as that of the third embodiment.

As can be seen from FIG. 31B, the actuator unit 382 has six straight line portions L23 to L28. Two of the connecting points of the linear portions L adjacent to each other of the actuator unit 382 (L
23 and L28, L25 and L26) form an arcuate portion F, which gently connects the straight line portions L to each other. Therefore, the arcuate portion F is extremely unlikely to be chipped. Even at this time, the angle (θ23 to θ2) formed between the adjacent straight line portions L including two straight line portions connected with the arcuate portion F interposed therebetween is also included.
All of 7) are 90 ° or more (approximately 120 °).

Next, a fourth embodiment of the present invention will be described with reference to FIG. In the inkjet head and the inkjet printer according to the present embodiment, parts other than the head body are similar to those in the above-described first embodiment, and therefore detailed description thereof will be omitted here.

The head main body 401 shown in FIG. 32 is provided with a flow path unit 404 in which a large number of pressure chambers and ink ejection ports are formed, as in the above-described embodiment, and the upper surface thereof has a parallelogram shape. Two actuator units 4
21 (in FIG. 32, the right one is indicated by reference numeral 421a and the left one is indicated by reference numeral 421b) are arranged and adhered. Each actuator unit 421 is arranged such that one side B thereof extends along the longitudinal direction of the head body 401. The adjacent actuator units 421 are arranged such that their hypotenuses C are close to each other and the head main body 401
Are arranged in the width direction of the. The two actuator units 421 partially overlap each other in the width direction of the flow path unit 404.
An ink supply port 402 is opened on the upper surface of the flow path unit 404, and the ink supply port 402 is connected to an ink supply source via a path not shown.

On the upper surface of the actuator unit 421, FPCs 436 for applying drive signals to individual electrodes and common electrodes in the actuator unit 421 are attached respectively. A driver IC 432, which is a drive circuit that generates a drive signal supplied to the individual electrodes in the actuator unit 421, is bonded onto each FPC 436. Each FPC 436 is electrically connected to a control unit 440 including a CPU, RAM and ROM. The control unit 440 supplies print data to the driver IC 432. The driver IC 432 generates a drive signal for the individual electrode based on the print data.

The actuator 421 has two areas P
21 and P22 are provided. Of which, the basic area P21
32 is a parallelogram having sides parallel to each side of the actuator 421, having a width slightly shorter than the side B of the actuator unit 421 and a length of about 3/4 of the side C, and It is provided in the upper portion of the actuator unit 421. The additional area P22 is a parallelogram having sides parallel to the respective sides of the actuator 421 and has the same width as the basic area P21.
It is provided below the basic region P21 in 21.
The additional region P22 is a parallelogram having two sides P22a and P2 each having a side parallel to each side of the actuator 421.
Divided into 2b. The section P22a has a width of about ⅕ of the side B of the actuator unit 421 and a length of about ⅕ of the side C, and in FIG.
It is in the vicinity of the lower left acute angle portion of 21. P22b is about 3/5 of the width of the side B of the actuator unit 421 and 1 of the side C.
It has a length of about / 5 and is on the lower side of the basic region P21 and on the right side of the section P22a in FIG.

In the two areas P22a and P22b of the basic area P21 and the additional area P22, a large number of pressure generating portions are adjacent to each other, and the direction along the longitudinal direction of the flow path unit 404 and the parallelogram shape. They are arranged in a matrix in the direction along the other side C. Then, ink flow paths including pressure chambers and nozzles are formed in the flow path unit 404 corresponding to the respective pressure generating portions.

When the two actuator units 421a and 421b having such a configuration are arranged side by side in the longitudinal direction of the flow path unit 404 as shown in FIG. 32, pressure is generated near the joint between the actuator unit 421a and the actuator unit 421b. Area without parts (Fig. 2
Since there is a region G) indicated by hatching in 3, when only the pressure generating portions in the basic region P11 are considered, the number of pressure generating portions along the width direction of the flow path unit 404 near the joint is It is less than in places other than near the seams.

Therefore, in this embodiment, the basic area P21
The area P22a of the additional area P22 provided below the area P22a is provided corresponding to the area G having no pressure generating portion near the joint in the width direction of the flow path unit 404. The control unit 440 causes the driver IC 43 to operate the pressure generating section in the basic area P21 and the pressure generating section in the area P22a of the additional area P22 and not operate the pressure generating section in the area P22b of the additional area P22.
Control 2 As a result, the actuator unit 4
In FIG. 21, the pressure generating portion is arranged substantially within the range of the same shape as the actuator unit 221 shown in FIG. 18, so that the flow path unit 40 near the joint is formed.
The number of pressure generating portions along the width direction of No. 4 is the same as other places. That is, the pressure generating portion in the area P22a of the additional region P22 is a gap portion between the pressure generating portion of the basic region P21 provided in the actuator unit 421a and the pressure generating portion of the basic region P21 provided in the adjacent actuator unit 421b. Head unit 401 capable of printing seamlessly over the entire longitudinal direction of the flow path unit without separately disposing an actuator unit for ejecting ink from the gap portion.
It is possible to provide. Furthermore, since the pressure generating portion forming range in the actuator unit 421 has a shape similar to that of the actuator unit 421, problems such as distortion and warpage of the actuator unit 421 are unlikely to occur.

As is clear from the above description,
In the present embodiment, the ink flow path may not be formed in the portion of the flow path unit 404 corresponding to the section P22b of the additional area P22.

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, the materials of the piezoelectric sheet and the electrodes used in the above-described embodiment are not limited to those described above, and other known materials may be used. In addition, the planar shape and cross-sectional shape of the pressure chamber, the arrangement form,
The number of piezoelectric sheets including the active layer, the number of inactive layers, and the like may be changed as appropriate. Further, the piezoelectric sheet including the active layer and the inactive layer may have different layer thicknesses.

Further, in the above-mentioned embodiment, the actuator unit is formed by disposing the individual electrodes and the common electrode on the piezoelectric sheet, but it is not always necessary to bond such an actuator unit to the flow path unit. Other actuator units may be used as long as they can individually change the volume of each pressure chamber. Further, in the above-described embodiment, the case where the pressure chambers are arranged in a matrix has been described, but the present invention can be applied to a case where the pressure chambers are arranged in one row or a plurality of rows. Further, in the above-described embodiment, the inactive layers are all piezoelectric sheets, but an insulating sheet other than the piezoelectric sheet may be used as the inactive layer.

[0150]

As described above, according to the present invention,
The actuator unit and the flow path unit can be accurately aligned.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an inkjet printer including an inkjet head according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the inkjet head according to the first embodiment of the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG.

4 is a plan view of a head body included in the inkjet head depicted in FIG. 2. FIG.

5 is an enlarged view of a region surrounded by an alternate long and short dash line drawn in FIG. 4. FIG.

FIG. 6 is an enlarged view of a region surrounded by an alternate long and short dash line drawn in FIG.

FIG. 7 is a partial cross-sectional view of the head body depicted in FIG.

FIG. 8 is an enlarged view of a region surrounded by a chain double-dashed line drawn in FIG.

9 is a partially exploded perspective view of the head body depicted in FIG.

FIG. 10 is an enlarged cross-sectional view of a region surrounded by a dashed line drawn in FIG. 7 as viewed from the lateral direction.

FIG. 11 is a plan view of a head body included in an inkjet head according to a second embodiment of the present invention.

12 is a bottom view of the head body shown in FIG.

13 is a cross-sectional view of the head body shown in FIG.

FIG. 14 is an enlarged view of a region Q surrounded by an alternate long and short dash line drawn in FIG.

15 is a partial cross-sectional view of the head body depicted in FIG.

16 is an enlarged cross-sectional view showing a detailed configuration of an actuator unit in the head main body shown in FIG.

17 is an enlarged plan view of an actuator unit in the head body shown in FIG.

FIG. 18 is an enlarged plan view illustrating a joint portion between the actuator units shown in FIG.

FIG. 19 is an enlarged plan view of an actuator unit according to a modification of the second embodiment of the present invention.

20 is an enlarged plan view illustrating a joint portion between the actuator units shown in FIG.

21A and 21B are plan views illustrating a head main body included in an inkjet head as a modified example of the present invention, which is configured by arranging four actuator units.

FIG. 22 is a plan view of a head body included in an inkjet head according to a third embodiment of the present invention.

23 is a bottom view of the head main body shown in FIG. 22. FIG.

24 is a cross-sectional view of the head body shown in FIG.

25 is an enlarged view of a region E surrounded by the alternate long and short dash line drawn in FIG.

26 is a partial cross-sectional view of the head body depicted in FIG.

27 is an enlarged cross-sectional view showing a detailed configuration of an actuator unit in the head main body shown in FIG.

28A is a schematic diagram showing a contour shape of an actuator unit included in the head main body shown in FIG. FIG. 28B is a schematic diagram showing a contour shape of an actuator unit as a modified example.

29 (a) is a plan view of a modification of the head body shown in FIG. 22 in which the actuator unit has a heptagonal shape. FIG. 29B is a plan view of the actuator unit included in the head body shown in FIG.

FIG. 30 (a) is a plan view of a modification of the head body shown in FIG. 22 in which the actuator unit has an octagonal shape. FIG. 30B is a plan view of the actuator unit included in the head body shown in FIG.

31 (a) is a plan view of a modification of the head body shown in FIG. 22 in which a part of the contour of the actuator unit is formed into an arc shape. FIG. 31 (b) shows FIG.
FIG. 3 is a plan view of an actuator unit included in the head body shown in FIG.

FIG. 32 is a schematic view of a main part of an inkjet printer according to a fourth embodiment of the present invention.

[Explanation of symbols]

1 inkjet head 3 ink pool 3a, 3b opening 5 manifold 5a Sub-manifold 8 ink outlet 10 Pressure chamber 12 apertures 21 Actuator unit 22 Cavity plate 30 nozzle plate 32 ink flow path 34a, 34b common electrode 35a, 35b Individual electrodes 41-43 Piezoelectric sheet (layer including active layer) 44, 45 Piezoelectric sheet (inactive layer)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Sakaida Atsushi             15-1 Naedai-cho, Mizuho-ku, Nagoya-shi, Aichi Prefecture             Within Lazer Industry Co., Ltd. F-term (reference) 2C057 AF65 AF93 AG15 AG33 AG38                       AG40 AG44 AG91 AN05 AP02                       AP23 AP31 AP54 AP77 BA04                       BA14

Claims (16)

[Claims] 1. A flow path unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane. A plurality of actuator units fixed to one surface of the flow path unit to change the volume of the chamber, each actuator unit having a plurality of pressure generating sections corresponding to each pressure chamber and a plurality of The actuator units are formed to have a size that straddles the pressure chamber, and the adjacent actuator units are arranged along the longitudinal direction of the flow path unit so that the actuator units overlap each other in the width direction of the flow path unit. And a plurality of actuator units, each actuator unit has a basic area in which a large number of the pressure generating portions are formed in a matrix, An additional region adjacent to the basic region in the width direction of the flow path unit, the pressure generating unit in the basic region, and the pressure generating unit in the basic region of another adjacent actuator unit. And an additional region in which the pressure generating portion is formed corresponding to a gap portion between the inkjet heads. 2. The ink jet head according to claim 1, wherein the actuator unit is a flat plate having a substantially quadrangular shape, and the additional region is provided in the vicinity of an acute angle portion. 3. The actuator unit is a flat plate having a substantially parallelogram shape, and a plurality of the actuator units have two opposite sides of one of the actuator units parallel to the longitudinal direction of the flow path unit. And the other two opposite sides are arranged adjacent to each other in the longitudinal direction of the flow path unit so that the two opposite sides are oblique with respect to the longitudinal direction of the flow path unit. The inkjet head according to claim 2, wherein the additional region is provided. 4. The pressure generating portion is not formed in a region adjacent to the additional region in the longitudinal direction of the flow channel unit and adjacent to the basic region in the width direction of the flow channel unit. The inkjet head according to claim 1. 5. The actuator unit is provided with a plurality of rows in which a large number of the pressure generating portions are arranged in the longitudinal direction of the flow path unit, and a virtual straight line in a direction orthogonal to the longitudinal direction of the flow path unit. 5. The inkjet head according to claim 4, wherein the number of the rows that intersect in the area where the adjacent actuator units overlap with each other is the same as the number of the rows that intersect in the area that does not overlap with each other. 6. The inkjet head according to claim 1, wherein two or more actuator units are arranged in a straight line along a longitudinal direction of the flow path unit. 7. A flow path unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane. A plurality of actuator units fixed to one surface of the flow path unit to change the volume of the chamber, each actuator unit having a plurality of pressure generating sections corresponding to each pressure chamber and a plurality of The actuator units are formed to have a size that straddles the pressure chamber, and the adjacent actuator units are arranged along the longitudinal direction of the flow path unit so that the actuator units overlap each other in the width direction of the flow path unit. And a plurality of actuator units, each actuator unit has a basic area in which a large number of the pressure generating portions are formed in a matrix, An additional region adjacent to the basic region in the width direction of the flow path unit, the pressure generating unit in the basic region, and the pressure generating unit in the basic region of another adjacent actuator unit. An ink jet printer including an ink jet head having an additional region in which the pressure generating portion is formed corresponding to a gap portion between the two. 8. A flow path unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane. A plurality of actuator units fixed to one surface of the flow path unit to change the volume of the chamber, each actuator unit having a plurality of pressure generating sections corresponding to each pressure chamber and a plurality of The actuator units are formed to have a size that straddles the pressure chamber, and the adjacent actuator units are arranged along the longitudinal direction of the flow path unit so that the actuator units overlap each other in the width direction of the flow path unit. And a plurality of actuator units, each actuator unit has a basic area in which a large number of the pressure generating portions are formed in a matrix, An inkjet head that is adjacent to the basic region in the width direction of the flow path unit and that includes an additional region in which the pressure generating unit is formed; a drive circuit that drives the inkjet head; At the time of driving the head, in the additional area, the pressure corresponding to a gap portion between the pressure generating section in the basic area and the pressure generating section in the basic area of another adjacent actuator unit. An inkjet printer, comprising: a control unit that controls the drive circuit so that only the generator is operated. 9. A flow path unit including a plurality of pressure chambers communicating with nozzles for ejecting ink, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane, and for changing the volume of the pressure chambers. And an actuator unit fixed to one surface of the flow path unit, the actuator unit having a plurality of pressure generating portions formed to have a size across the plurality of pressure chambers and corresponding to the pressure chambers. An ink jet head having an outline shape having at least three straight line portions, and an actuator unit in which each straight line portion is connected to an adjacent straight line portion at either a right angle or an obtuse angle. 10. The ink jet head according to claim 9, wherein a plurality of the actuator units are arranged along the longitudinal direction of the flow path unit. 11. The ink jet head according to claim 9, wherein at least one of the connecting portions of the straight line portions has an arcuate portion. 12. A flow path unit including a plurality of pressure chambers, one end of which is connected to a nozzle and the other end of which is connected to an ink supply source, wherein the plurality of pressure chambers are arranged adjacent to each other along a plane. A plurality of actuator units fixed to one surface of the flow path unit to change the volume of the chamber, each actuator unit having a plurality of pressure generating sections corresponding to each pressure chamber and a plurality of An ink jet head comprising: a plurality of actuator units, which are formed to have a size extending over the pressure chambers and are arranged along a longitudinal direction of the flow path unit. 13. The actuator unit includes one or a plurality of active layers made of a piezoelectric sheet sandwiched by a common electrode kept at a constant potential and an individual electrode arranged at a position corresponding to each pressure chamber. The inkjet head according to claim 12, 14. The ink jet head according to claim 13, wherein one or more inactive layers made of a piezoelectric sheet are arranged between the active layer and the flow path unit. 15. The ink jet head according to claim 12, wherein the plurality of pressure chambers are arranged in a matrix while being adjacent to each other. 16. The actuator unit, wherein the actuator unit has a substantially trapezoidal shape, and a plurality of the actuator units have the parallel opposing sides of each actuator unit along the longitudinal direction of the flow path unit and adjacent to each other. 16. The inkjet head according to any one of claims 12 to 15, wherein a plurality of rows are arranged in a zigzag pattern so that the oblique sides of the above overlap each other in the width direction of the flow path unit.