WO2018225553A1

WO2018225553A1 - Inkjet head and inkjet recording device

Info

Publication number: WO2018225553A1
Application number: PCT/JP2018/020289
Authority: WO
Inventors: 光濱野
Original assignee: コニカミノルタ株式会社
Priority date: 2017-06-09
Filing date: 2018-05-28
Publication date: 2018-12-13
Also published as: EP3636438B1; EP3636438A4; CN110709251B; JP7078044B2; JPWO2018225553A1; EP3636438A1; CN110709251A

Abstract

In order to alleviate imbalances in temperature in the pressure chambers inside of a head tip, this inkjet head is provided with multiple nozzles 111 which inject ink, pressure chambers 131 which communicate with each of the nozzles and in which ink is stored, a pressure generating means (the partition wall 136) which pressurizes the ink in the pressure chamber, individual ink discharge paths 121 which are provided branching from each of the pressure chambers and which can discharge the ink in said pressure chambers, and a common ink discharge path 133 which to which the individual ink discharge paths are linked. The nozzles and pressure chambers form rows R1 to R4 in a direction along two opposite outer surfaces DS of the head chip 1, and said rows are arranged side by side in a direction perpendicular to the outer surface. The common ink discharge path 133 is provided extending in a direction along the two outer surfaces. The common ink discharge path is arranged only in two outermost regions (D1+D2), which are near one outer surface and do not have the aforementioned rows R1-R4 interposed therebetween, and/or a center region D4 between the two outer surfaces.

Description

Inkjet head and inkjet recording apparatus

The present invention relates to an inkjet head and an inkjet recording apparatus.

2. Description of the Related Art Conventionally, an ink jet recording apparatus that forms an image on a recording medium by ejecting ink stored in a pressure chamber from a plurality of nozzles provided in the ink jet head is known.
In such an ink jet recording apparatus, there are cases where the nozzles are clogged due to bubbles generated in the ink jet head, foreign matters mixed therein, or the like, resulting in problems such as defective injection. In addition, depending on the type of ink, if the ink is left unused for a long time, the ink viscosity near the nozzle may increase due to sedimentation of ink particles, and it may be difficult to obtain stable ink ejection performance.

In view of this, an ink jet head that includes a flow path capable of circulating the ink in the pressure chamber in the head and can discharge bubbles, foreign matters, and the like in the head together with the ink is known (for example, see Patent Document 1). ).
For example, Patent Document 1 discloses an ink jet head provided with an individual ink discharge path capable of discharging ink from each pressure chamber and a common ink discharge path where a plurality of individual ink discharge paths merge in the head. Has been.

Japanese Patent No. 5385975

As shown in FIG. 16, in the head chip 1, a nozzle 111, a pressure chamber 131 disposed above the nozzle 111, an individual ink discharge path 121 extending from the pressure chamber 131, and each individual ink discharge path 121 merge. And a common ink discharge path 133 (first common ink discharge path 134).
The outer surface DS of the head chip 1 shown in the figure is an outer surface along the longitudinal direction of the head chip 1, and the nozzle 111 and the pressure chamber 131 connected thereto form a row (R1, R2) along the outer surface DS. . Between the outer surface DS and the central plane DC when vertically penetrating into the interior, two rows of nozzles 111 and pressure chambers 131 connected to the nozzles 111 are configured, for example.
The common ink discharge path 133 is extended in the direction along the outer surface DS in order to receive the merging of the individual ink discharge paths 121 from the plurality of pressure chambers 131 forming a row in the direction along the outer surface DS. Yes.
In such a head chip 1, the outer surface DS to the center plane DC will be described by dividing into regions D11 to D15 as illustrated in the depth direction perpendicular to the inner surface DS.
The thermal conditions are not uniform over the regions D11-D15. This is because the common ink discharge path 133 has a cooling effect and a heat insulating effect because a relatively large amount of ink flows. For example, the temperature distribution TD when the high heat source is outside the outer surface DS is shown in the figure. The darker the temperature distribution TD, the higher the temperature. Since there is no common ink discharge path 133 between the area D11 and the outer surface DS, the outside heat is easily transmitted to the area D11. On the other hand, the region D13 has a single common ink discharge path 133 up to the outer surface DS, so that heat is not easily transmitted compared to the region D11, and the temperature is relatively low.
Therefore, the ink temperature in the pressure chamber 131 in the region D11 is relatively high, the ink temperature in the pressure chamber 131 in the region D13 is relatively low, and vice versa when dissipating heat to the outside. There is a problem that the image quality may be affected because the temperature of the image becomes uneven.
In FIG. 16, only one side region from the outer surface DS to the center plane DC is shown, but it is usually configured symmetrically in the region from the opposite outer surface to the center plane DC.

The present invention has been made in view of such problems, and an object of the present invention is to provide an ink jet head and an ink jet recording apparatus that can alleviate temperature imbalance in each pressure chamber in the head chip. That is.

In order to solve the above problem, the invention according to claim 1 is an inkjet head,
A plurality of nozzles for ejecting ink;
A plurality of pressure chambers communicating with each of the plurality of nozzles and storing ink;
A plurality of pressure generating means provided corresponding to each of the plurality of pressure chambers, for applying pressure to the ink in the pressure chamber;
A plurality of individual ink discharge paths that are branched from each of the plurality of pressure chambers and capable of discharging ink in the plurality of pressure chambers;
A common ink discharge path connected to the plurality of individual ink discharge paths,
The plurality of nozzles and the plurality of pressure chambers form a row in a direction along two opposing outer surfaces of the head chip, and a plurality of the rows are provided in a direction perpendicular to the outer surface,
The common ink discharge path extends in a direction along the two outer surfaces;
The common ink discharge path is disposed only in one or both of the outermost regions adjacent to one of the outer surfaces and the central region between the two outer surfaces without passing through the row. .

The invention according to claim 2 is the ink jet head according to claim 1,
Three or more rows are provided.

The invention according to claim 3 is the ink jet head according to

claim

1 or 2,
The columns are provided in even columns.

According to a fourth aspect of the invention, there is provided the inkjet head according to any one of the first to third aspects,
The common ink discharge path and the one common ink through the one line by the individual ink discharge path belonging to one row and provided between the two adjacent pressure chambers. The pressure chambers belonging to other rows arranged on the opposite side of the discharge path are connected.

The invention according to claim 5 is the inkjet head according to any one of claims 1 to 4,
The head chip includes, in order, a nozzle substrate provided with the plurality of nozzles, a flow path spacer substrate provided with the plurality of individual ink discharge paths, and a pressure chamber substrate provided with the plurality of pressure chambers. It is configured by stacking.

The invention according to claim 6 is the inkjet head according to any one of claims 1 to 5,
The row is configured by alternately arranging the pressure chambers and air chambers isolated from the ink flow path,
The individual ink discharge path is disposed so as to overlap the air chamber when viewed in the axial direction of the nozzle.

The invention according to claim 7 is the inkjet head according to any one of claims 1 to 6,
At least two individual ink discharge paths are provided in each of the plurality of pressure chambers.

The invention according to claim 8 is the inkjet head according to any one of claims 1 to 7,
The common ink discharge path is arranged in both the outermost regions.

The invention according to claim 9 is the inkjet head according to any one of claims 1 to 8,
The common ink discharge path is disposed in the central region.

The invention according to claim 10 is the ink jet head according to claim 9,
Two of the common ink discharge paths are arranged in the central region without interposing the row.

The invention according to claim 11 is an ink jet recording apparatus,
An inkjet head according to any one of claims 1 to 10,
Ink supply means for generating a circulating flow from the pressure chamber to the individual ink discharge path;
Is provided.

According to the present invention, it is possible to provide an ink jet head and an ink jet recording apparatus that can alleviate the temperature imbalance of each pressure chamber in the head chip.

Schematic diagram showing inkjet recording device Bottom view of head unit Perspective view of inkjet head Cross section of inkjet head Exploded perspective view of inkjet head Exploded perspective view of head chip Plan view of pressure chamber substrate Bottom view of pressure chamber substrate Plan view of channel spacer substrate Bottom view of channel spacer substrate Top view of the nozzle substrate Sectional view of the head chip when cut with IXA-IXA Cross section of the head chip when cut with IXB-IXB Cross section of the head chip when cut with XA-XB Cross section of the head chip when cut with XA-XB Schematic diagram showing the ink circulation system Schematic diagram showing the layout of an example of each element in the head chip Schematic diagram showing the arrangement of another example of each element in the head chip in a plan view Schematic diagram showing the arrangement of another example of each element in the head chip in a plan view Schematic diagram showing the arrangement of another example of each element in the head chip in a plan view Schematic diagram showing the layout of each element in the head chip of the comparative example in a plan view

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In this specification, for convenience of explanation, the print width direction, which is the arrangement direction of the nozzles 111 of the inkjet head 100, is the left-right direction, the direction in which the recording medium is conveyed below the nozzles 111 is the front-back direction, and the left-right direction. The direction perpendicular to the front-rear direction will be described as the vertical direction. Moreover, the arrow in the flow path of drawing shows the direction through which ink flows.

[Inkjet recording apparatus]
As shown in FIG. 1, the ink jet recording apparatus 200 includes a paper feed unit 210, an image recording unit 220, a paper discharge unit 230, an ink circulation system 8 (see FIG. 11) as an ink supply unit, and the like. The ink jet recording apparatus 200 conveys the recording medium M stored in the paper feeding unit 210 to the image recording unit 220, forms an image on the recording medium M with the image recording unit 220, and discharges the recording medium M on which the image is formed. Transport to paper section 230.

The paper feed unit 210 includes a paper feed tray 211 that stores the recording medium M, and a medium supply unit 212 that conveys and supplies the recording medium M from the paper feed tray 211 to the image recording unit 220. The medium supply unit 212 includes a ring-shaped belt that is supported by two rollers on the inside, and the recording medium M is removed from the paper feed tray 211 by rotating the roller while the recording medium M is placed on the belt. The image is transferred to the image recording unit 220.

The image recording unit 220 includes a transport drum 221, a delivery unit 222, a heating unit 223, a head unit 224, a fixing unit 225, a delivery unit 226, and the like.

The transport drum 221 has a cylindrical surface, and the outer peripheral surface thereof is a transport surface on which the recording medium M is placed. The conveyance drum 221 conveys the recording medium M along the conveyance surface by rotating in the direction of the arrow in FIG. 1 while holding the recording medium M on the conveyance surface. Further, the transport drum 221 includes a claw portion and an air intake portion (not shown), presses the end of the recording medium M by the claw portion, and sucks the recording medium M to the transport surface by the air intake portion. The recording medium M is held.

The delivery unit 222 is provided at a position between the medium supply unit 212 and the conveyance drum 221 of the paper supply unit 210, and picks up one end of the recording medium M conveyed from the medium supply unit 212 by the swing arm unit 222a. Then, it is delivered to the transport drum 221 through the delivery drum 222b.

The heating unit 223 is provided between the arrangement position of the transfer drum 222b and the arrangement position of the head unit 224, and the recording medium M conveyed by the conveyance drum 221 has a temperature within a predetermined temperature range. Heat M. The heating unit 223 includes, for example, an infrared heater, and energizes the infrared heater based on a control signal supplied from a control unit (not shown) to cause the heater to generate heat.

The head unit 224 forms an image by ejecting ink to the recording medium M at an appropriate timing according to the rotation of the transport drum 221 holding the recording medium M based on the image data. The head unit 224 is disposed at a predetermined distance with the ink ejection surface facing the transport drum 221. In the ink jet recording apparatus 200 of the present embodiment, for example, four head units 224 corresponding respectively to four colors of ink of yellow (Y), magenta (M), cyan (C), and black (K) are included in the recording medium M. Are arranged at predetermined intervals in the order of colors Y, M, C, and K from the upstream side in the transport direction.

In the head unit 224, for example, as shown in FIG. 2, a pair of inkjet heads 100 adjacent to each other in the front-rear direction are arranged in a staggered manner at different positions in the front-rear direction. Further, the head unit 224 is used with its position relative to the rotation axis of the transport drum 221 fixed when recording an image. That is, the ink jet recording apparatus 200 is an ink jet recording apparatus 200 that performs one-pass drawing type image recording using a line head.

The fixing unit 225 includes a light emitting unit arranged over the width of the transport drum 221 in the X direction, and irradiates the recording medium M placed on the transport drum 221 with energy rays such as ultraviolet rays from the light emitting unit. Then, the ink ejected on the recording medium M is cured and fixed. The light emitting unit of the fixing unit 225 is disposed opposite to the conveyance surface on the downstream side of the arrangement position of the head unit 224 and the upstream side of the arrangement position of the delivery drum 226a of the delivery unit 226 in the conveyance direction.

The delivery unit 226 includes a belt loop 226b having an annular belt supported on the inside by two rollers, and a cylindrical delivery drum 226a that delivers the recording medium M from the transport drum 221 to the belt loop 226b. The recording medium M transferred from the transport drum 221 onto the belt loop 226b by the transfer drum 226a is transported by the belt loop 226b and sent to the paper discharge unit 230.

The paper discharge unit 230 includes a plate-shaped paper discharge tray 231 on which the recording medium P sent out from the image recording unit 220 by the delivery unit 226 is placed.

[Inkjet head]
As shown in FIGS. 3A, 3B, and 4, the inkjet head 100 according to this embodiment includes a head chip 1, a wiring board 2 on which the head chip 1 is disposed, a wiring board 2, and a flexible board 3. Connected to the drive circuit board 4, a manifold 5 for storing ink to be supplied to the pressure chamber 131 in the head chip 1, a housing 6 in which the manifold 5 is housed, and a bottom opening of the housing 6 are closed. The cap receiving plate 7 attached in this way, the cover member 9 attached to the housing 6 and the like are provided.
3A, illustration of the manifold 5 is omitted, and in FIG. 3B and FIG. 4, illustration of the cover member 9 is omitted.
In the present embodiment, an example in which the number of nozzles 111 of the head chip 1 is four will be basically described.

The head chip 1 is a substantially quadrangular prism-like member elongated in the left-right direction, and is configured by sequentially stacking a pressure chamber substrate 13, a flow path spacer substrate 12, and a nozzle substrate 11 (FIGS. 5 to 11). ).

The pressure chamber substrate 13 is provided with a pressure chamber 131, an air chamber 132, a common ink discharge path 133, and the like (see FIGS. 5, 6A, and 6B).
A large number of pressure chambers 131 and air chambers 132 are provided so as to be alternately arranged in the left-right direction, and are provided in four rows in the front-rear direction.
The pressure chamber 131 has a substantially rectangular cross section and is formed along the vertical direction. The pressure chamber 131 has an inlet on the upper surface of the pressure chamber substrate 13 and an outlet on the lower surface. The pressure chamber 131 communicates with the ink reservoir 51 at the upper end, and ink is supplied from the ink reservoir 51 to the pressure chamber 131 and ejected from the nozzle 111 into the pressure chamber 131. Ink for storing is stored. Further, the pressure chamber 131 is formed along the vertical direction so as to have a substantially rectangular cross section of the same area, straddling the pressure chamber substrate 13 and the flow path spacer substrate 12. This part communicates with the nozzle 111 (see FIG. 9A, FIG. 9B, etc.).

The air chamber 132 has a substantially rectangular cross section that is slightly larger than the pressure chamber 131 and is formed to be parallel to the pressure chamber 131 along the vertical direction. Further, unlike the pressure chamber 131, the air chamber 132 is not communicated with the ink reservoir 51, so that ink does not flow into the air chamber 132. Moreover, the air chamber 132 is not connected also to the nozzle 111 (refer FIG. 9A, FIG. 9B etc.).

The pressure chamber 131 and the air chamber 132 are formed to be separated from each other by a partition wall 136 as pressure generating means formed of a piezoelectric material (see FIG. 10A). The partition wall 136 is provided with a drive electrode (not shown), and when a voltage is applied to the drive electrode, the partition wall 136 portion between the adjacent pressure chambers 131 repeats a shear mode type displacement, whereby the inside of the pressure chamber 131. Pressure is applied to the ink. Note that the pressure chamber 131 shown in FIGS. 5 to 10 and the like does not use the pressure chamber 131 located at the end in the left-right direction, which has the partition wall 136 only on one side, and the pressure chamber 131 on the other side. The chamber 131 is used.

Although the air chamber 132 may not be provided and only the pressure chamber 131 may be formed, it is preferable to alternately provide the pressure chamber 131 and the air chamber 132 as described above. Accordingly, the pressure chambers 131 can be prevented from being adjacent to each other, so that when the partition wall 136 adjacent to one pressure chamber 131 is deformed, the other pressure chambers 131 are not affected.

The common ink discharge path 133 is configured by connecting a first common ink discharge path 134 and a second common ink discharge path 135 (see FIGS. 5 and 6B and the like).
The first common ink discharge path 134 avoids a portion where the pressure chamber 131 and the air chamber 132 are provided on the lower surface side of the pressure chamber substrate 13, so that the front side, the rear side, and the center portion of the head chip 1 are disposed. In addition, three rows are provided along the left-right direction. In addition, a plurality of individual ink discharge paths 121 provided on the flow path spacer substrate 12 are connected to the lower surface side of the first common ink discharge path 134, and these individual ink discharge paths 121 (second individual ink discharge paths 123) are connected. ) Can flow in the first common ink discharge path 134 (FIGS. 6B, 7A, and 9A). The first common ink discharge path 134 is connected to a second common ink discharge path 135 that can discharge ink to the outside of the head chip 1 near the right end. Therefore, the first common ink discharge path 134 is a flow path in which the ink flowing from the individual ink discharge path 121 (second individual ink discharge path 123) flows toward the second common ink discharge path 135. .

The second common ink discharge path 135 is formed along the vertical direction, like the pressure chamber 131. The second common ink discharge path 135 has a lower surface side of the pressure chamber substrate 13 communicating with the first common ink discharge path 134, and an upper surface side thereof connected with the discharge liquid chamber 57. This is a flow path for discharging the ink flowing from 134 toward the upper side (the side opposite to the nozzle substrate 11 side) to the outside of the head chip 1. The second common ink discharge path 135 is provided near the right end of the head chip 1 and communicates with the first common ink discharge path 134. Further, by providing the second common ink discharge path 135 so as to have a larger volume than the individual pressure chambers 131, the ink discharge efficiency can be increased.

The flow path spacer substrate 12 is formed with a pressure chamber 131 and an individual ink discharge path 121 branched from the pressure chamber 131 (FIGS. 5, 7A, 7B, 9A and 9A and 9B). 9B etc.).
The pressure chamber 131 is formed along the vertical direction so as to straddle the flow path spacer substrate 12 and the pressure chamber substrate 13 and to have a substantially rectangular cross section of the same area.

The individual ink discharge path 121 has one end connected to the pressure chamber 131 and the other end connected to the first common ink discharge path 134, and discharges the ink in the pressure chamber 131 to the first common ink discharge path 134. It is a flow path.
It is preferable that at least two individual ink discharge paths 121 are provided in each of the pressure chambers 131 from the viewpoint of facilitating discharge of bubbles, foreign matter, and the like together with ink. In addition, for example, as shown in FIGS. 9A and 9B, two individual ink discharge paths 121 are provided, one each in the front direction and the rear direction of the pressure chamber 131, so that bubbles, foreign matters, and the like can be formed together with the ink. It is preferable because the effect of facilitating discharge can be obtained and the production efficiency is high.

The individual ink discharge path 121 is configured by connecting a first individual ink discharge path 122 and a second individual ink discharge path 123. One end of the first individual ink discharge path 122 is connected to the pressure chamber 131, and extends in the front-rear direction on the lower surface side portion of the flow path spacer substrate 12. The second individual ink discharge path 123 is connected to the other end of the first individual ink discharge path 122, extends upward, and is connected to the first common ink discharge path 134.

Regarding the arrangement of the nozzle 111, the pressure chamber 131, the air chamber 132, the individual ink discharge path 121, and the common ink discharge path 133 (first common ink discharge path 134) as viewed in the axial direction described above. This will be described with reference to the schematic diagrams of FIGS. This arrangement is intended to alleviate the temperature imbalance of each pressure chamber in the head chip 1.

In the head chip 1 shown in FIG. 12, a plurality of nozzles 111 and a plurality of pressure chambers 131 are arranged in a direction (left-right direction) along two opposing outer surfaces DS, DS of the head chip 1 (hereinafter referred to as “channel”). 4 rows (referred to as R1 to R4) are provided side by side in the direction (front-rear direction) perpendicular to the outer surface DS.
In addition, a first common ink discharge path 134 is extended in a direction (left-right direction) along the two outer surfaces DS, DS.
In the head chip 1, one outer surface DS to the other outer surface DS will be described by dividing into regions D1 to D7 as illustrated in the depth direction perpendicular to the inner surface DS.
The first common ink discharge path 134 includes both outermost regions (D1 + D2, D6 + D7) close to one of the outer surfaces DS without passing through any channel row R1-R4, and a central region between the two outer surfaces DS, DS. It is arranged on both sides of D4 and is arranged only in these areas.
That is, the first common ink discharge path 134 is disposed in the regions D2, D4, and D6, the regions D1 and D7 are outer wall portions to the outer surface DS, and the region D3 between the region D2 and the central region D4 includes Two channel rows R1, R2 are arranged, and two channel rows R3, R4 are arranged in a region D5 between the region D6 and the central region D4. The number of channel columns R1-R4 is three or more and an even number. By setting the even number of rows, the first common ink discharge path 134 passing through the center plane DC can be arranged, and the same number of channel rows can be arranged on both sides of the center plane DC, so that the thermal conditions can be made uniform.

An individual ink discharge path 121 which belongs to one row and is provided between two pressure chambers 131 adjacent to each other is connected to one first common ink discharge path 134 via the one row. A pressure chamber 131 belonging to another row arranged on the opposite side of the first common ink discharge path 134 is connected.
For example, the one column will be described as a channel column R1. The first common ink discharge path 134 disposed in the region D2 and the channel line R2 are separated by the individual ink discharge path 121 belonging to the channel line R1 and provided between the two

pressure chambers

131 and 131 adjacent to each other. The pressure chamber 131 to which it belongs is connected.
The one column will be described as a channel column R2. The first common ink discharge path 134 disposed in the region D4 and the channel line R1 are separated by the individual ink discharge path 121 belonging to the channel row R2 and provided between the two

pressure chambers

131 and 131 adjacent to each other. The pressure chamber 131 to which it belongs is connected.
The same applies to the region D5.
With this structure, the pressure chamber 131 of each channel row R1-R4 can be connected to the first common

ink discharge paths

134 and 134 on both sides by extending the individual ink discharge paths 121 in the front-rear direction. As a result, it is possible to improve the circulation of the ink and alleviate the temperature imbalance in the head chip 1.

The channel row is configured by alternately arranging the pressure chambers 131 and the air chambers 132 isolated from the ink flow paths as described above. As shown in FIG. 12, the individual ink discharge path 121 is disposed so as to overlap the air chamber 132 when viewed in the axial direction (vertical direction) of the nozzle 111. Thereby, thermal conductivity is improved.

According to the head chip 1 having the above structure, the temperature imbalance in the region D3 is alleviated, the temperature imbalance in the region D5 is also alleviated, and the temperature imbalance in the regions D3 and D5 is also alleviated. The
For example, the temperature distribution TD when the high heat source is outside the outer surface DS is shown in the figure. The darker the temperature distribution TD, the higher the temperature. The areas D1 and D7 have a first common ink discharge path 134 up to the outer surface DS, so that external heat is easily transmitted and the temperature rises. Since the areas D3 and D5 have one common ink discharge path 133 before reaching the outer surface DS, heat is not easily transmitted compared to the area D1, but the temperature is relatively low. Since the thermal conditions of the number of discharge paths 133 are the same, the temperatures in the regions D3 and D5 are made uniform. When the heat is radiated to the outside, the reverse is true, and the regions D1 and D7 have a lower temperature than the regions D3 and D5, but the temperature in the regions D3 and D5 remains uniform.
Therefore, the ink temperature imbalance in the pressure chambers 131 belonging to all the channel rows R1-R4 is alleviated and the temperature of the ejected ink becomes uniform, so that one of the thermal problems that can affect the image quality can be solved. .

13 to 15 are modifications to the structure shown in FIG.
FIG. 13 shows a structure in which one individual ink discharge path 121 extending from one pressure chamber 131 is connected to a first common ink discharge path 134 that is close. Even in the structure of the head chip 1, the thermal conditions such as the number of the common ink discharge paths 133 up to the outer surface DS are the same. Therefore, the temperatures in the regions D3 and D5 where the channel rows R1-R4 are present are Make uniform.

FIG. 14 shows a structure in which two first common ink discharge paths 134 are arranged in the central area D4 without interposing a channel row, and FIG. 15 shows a structure in which the common ink discharge paths 133 are not arranged in the central area D4. Show. The presence / absence and number of common ink discharge paths in the central area D4 do not affect the thermal condition of the number of common ink discharge paths 133 up to the outer surface DS. The temperature becomes uniform.
In the head chip 1 shown in FIG. 14, the channel row is not disposed between the two first common

ink discharge paths

134 and 134 in the central region D4. This is because the thermal condition of the number of common ink discharge paths 133 to the outer surface DS differs from the other channel rows.

As described above, as described with reference to FIGS. 12 to 15, the temperature imbalance of each pressure chamber 131 in the head chip 1 can be alleviated.

Although the first individual ink discharge path 122 of the present embodiment is provided in the lower surface side portion of the flow path spacer substrate 12 adjacent to the nozzle substrate 11, it is not limited thereto. For example, the first individual ink discharge path 122 may be provided so as to straddle both the nozzle substrate 11 and the channel spacer substrate 12, or may be provided only on the nozzle substrate 11, or the bottom surface of the channel spacer substrate 12. It may be provided slightly above the nozzle substrate 11 so as not to be adjacent to the nozzle substrate 11.

As shown in FIG. 4, a wiring board 2 is disposed on the upper surface of the head chip 1, and two flexible boards 3 connected to the drive circuit board 4 at both edges along the front-rear direction of the wiring board 2. Is arranged.

The wiring board 2 is formed in a substantially rectangular plate shape that is long in the left-right direction, and has an opening 22 at a substantially central portion thereof. Each width of the wiring substrate 2 in the left-right direction and the front-rear direction is formed larger than that of the head chip 1.

The opening 22 is formed in a substantially rectangular shape that is long in the left-right direction. When the head chip 1 is attached to the wiring board 2, the opening 22 is shared with the inlet of each pressure chamber 131 in the head chip 1. The outlet of the ink discharge path 135 is exposed to the upper side.

The flexible board 3 electrically connects the drive circuit board 4 and the electrode part of the wiring board 2, and a signal from the drive circuit board 4 is provided on the partition 136 in the head chip 1 via the flexible board 3. The drive electrode can be applied.

Further, the lower end portion of the manifold 5 is attached and fixed to the outer edge portion of the wiring board 2 by adhesion. That is, the manifold 5 is disposed on the inlet side (upper side) of the pressure chamber 131 of the head chip 1 and is connected to the head chip 1 via the wiring board 2.

The manifold 5 is a member formed of resin, is provided on the pressure chamber 131 of the head chip 1, and stores ink introduced into the pressure chamber 131. Specifically, as shown in FIG. 3B and the like, the manifold 5 is formed in an elongated shape in the left-right direction, and a hollow main body 52 that constitutes the ink reservoir 51 and a first that constitutes the ink flow path. 1 to 4th ink ports 53 to 56 are provided. The ink reservoir 51 is divided into two parts, an upper first liquid chamber 51a and a lower second liquid chamber 51b, by a filter F for removing dust in the ink.

The first ink port 53 communicates with the upper right end portion of the first liquid chamber 51 a and is used for introducing ink into the ink storage portion 51. In addition, a first joint 81 a is externally inserted at the tip of the first ink port 53.
The second ink port 54 communicates with the upper left end of the first liquid chamber 51a, and is used to remove bubbles in the first liquid chamber 51a. Further, a second joint 81 b is externally inserted at the tip of the second ink port 54.
The third ink port 55 communicates with the upper left end of the second liquid chamber 51b and is used to remove bubbles in the second liquid chamber 51b. A third joint 82 a is externally inserted at the tip of the third ink port 55.
The fourth ink port 56 communicates with a discharge liquid chamber 57 that communicates with the second common ink discharge path 135 of the head chip 1, and the ink discharged from the head chip 1 passes through the fourth ink port 56 and is inkjet It is discharged outside the head 100.

The housing 6 is a member formed by a die-cast method using, for example, aluminum as a material, and is formed long in the left-right direction. Further, the housing 6 is formed so as to be able to accommodate a manifold 5 to which the head chip 1, the wiring substrate 2 and the flexible substrate 3 are attached, and the bottom surface of the housing 6 is opened. In addition, attachment holes 68 for attaching the housing 6 to the printer main body side are formed at both ends in the left-right direction of the housing 6.

The cap receiving plate 7 has a nozzle opening 71 elongated in the left-right direction at a substantially central portion thereof, and the nozzle substrate 11 is exposed through the nozzle opening 71 so that the housing 6 It is attached to close the bottom opening.

[Ink circulation system]
The ink circulation system 8 is ink supply means for generating a circulation flow of ink from the pressure chamber 131 in the inkjet head 100 to the individual ink discharge path 121. The ink circulation system 8 includes a supply sub tank 81, a circulation sub tank 82, a main tank 83, and the like (FIG. 11).

The supply sub tank 81 is filled with ink to be supplied to the ink reservoir 51 of the manifold 5, and is connected to the first ink port 53 by an ink flow path 84.
The circulation sub tank 82 is filled with the ink discharged from the discharge liquid chamber 57 of the manifold 5, and is connected to the fourth ink port 56 by the ink flow path 85.
The supply sub-tank 81 and the circulation sub-tank 82 are provided at different positions in the vertical direction (gravity direction) with respect to the nozzle surface of the head chip 1 (hereinafter also referred to as “position reference surface”). As a result, a pressure P1 due to a water head difference between the position reference surface and the supply sub tank 81 and a pressure P2 due to a water head difference between the position reference surface and the circulation sub tank 82 are generated.
The supply sub-tank 81 and the circulation sub-tank 82 are connected by an ink flow path 86. Ink can be returned from the circulation sub-tank 82 to the supply sub-tank 81 by the pressure applied by the pump 88.

The main tank 83 is filled with ink to be supplied to the supply sub-tank 81, and is connected to the supply sub-tank 81 by the ink flow path 87. Ink can be supplied from the main tank 83 to the supply sub-tank 81 by the pressure applied by the pump 89.

Further, the pressure P1 and the pressure P2 can be adjusted by appropriately changing the ink filling amount in each sub tank and the position in the vertical direction (gravity direction) of each sub tank. The ink in the inkjet head 100 can be circulated at an appropriate circulation flow rate by the pressure difference between the pressure P1 and the pressure P2. Thereby, bubbles, foreign matter, etc. generated in the head chip 1 can be removed, and clogging of the nozzle 111, injection failure, and the like can be suppressed.

Note that, as an example of the ink circulation system 8, the method for controlling the circulation of the ink by the water head difference has been described. However, the configuration can be appropriately changed as long as the configuration can generate the ink circulation.

[Others]
The embodiment of the present invention described above should be considered as illustrative in all points and not restrictive. That is, the scope of the present invention is shown not by the above description but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

For example, although the example in which one of the flow path walls is formed by the nozzle substrate 11 is shown as the first individual ink discharge path 122 of the present embodiment, the present invention is not limited thereto.

Moreover, as the head chip 1 of the present embodiment, an example in which the nozzle substrate 11, the flow path spacer substrate 12, and the pressure chamber substrate 13 are sequentially stacked is shown, but the present invention is not limited thereto, and the nozzle substrate 11 and the pressure chamber substrate 13 A two-layer structure may be used. In this case, an individual ink discharge path 121 may be provided on at least one of the nozzle substrate 11 and the pressure chamber substrate 13.

In addition, although an example of the share mode type is shown as the inkjet head 100 of the present embodiment, it is only necessary to provide a means for applying pressure to the ink in the pressure chamber 131, and the present invention is not limited to this.

In addition, although an example of a one-pass drawing method using a line head has been shown as a drawing method of the inkjet recording apparatus 200 of the present embodiment, the present invention is not limited to this, and for example, a scanning method may be used.

In addition, although the example in which the ink inside the head chip 1 is circulated is shown as the ink circulation system 8 of the present embodiment, the ink in the second common ink discharge path 135 may be discharged without being circulated. It is good also as a structure which can select whether to discharge.

In addition, although an example in which the pressure chamber 131 and the second common ink discharge path 135 are open at the upper and lower surfaces of the head chip 1 is shown as the head chip 1 of the present embodiment, the present invention is not limited thereto. For example, it may be configured to open on any side surface of the head chip 1 in the front-rear and left-right directions, or may have a bent portion that changes the direction of ink flow in the middle of the flow path.

In the head chip 1 shown in FIGS. 12 to 15, a total of four channel rows are arranged with two rows on one side with respect to the center plane DC. You may arrange | position the channel row | line beyond a row | line | column.

In the head chip 1 shown in FIG. 12 to FIG. 15, even-numbered channel columns are arranged, but the present invention is not limited to this, and three or more odd-numbered channel columns may be arranged. For example, in the head chip 1 shown in FIG. 15, one channel row may be arranged in the central region D4, and the same number of channel rows may be arranged on both sides thereof. Also in this case, the thermal condition of the number of common ink discharge paths 133 up to the outer surface DS is the same.

The present invention can be used for an inkjet head and an inkjet recording apparatus.

1 Head chip 8 Ink circulation system (ink supply means)
11 Nozzle substrate 111 Nozzle 12 Flow path spacer substrate 121 Individual ink discharge path 122 First individual ink discharge path 123 Second individual ink discharge path 13 Pressure chamber substrate 131 Pressure chamber 132 Air chamber 133 Common ink discharge path 134 First common ink discharge Path 135 Second common ink discharge path 136 Partition (pressure generating means)
100 Inkjet head 200 Inkjet recording apparatus

Claims

A plurality of nozzles for ejecting ink;
A plurality of pressure chambers communicating with each of the plurality of nozzles and storing ink;
A plurality of pressure generating means provided corresponding to each of the plurality of pressure chambers, for applying pressure to the ink in the pressure chamber;
A plurality of individual ink discharge paths that are branched from each of the plurality of pressure chambers and capable of discharging ink in the plurality of pressure chambers;
A common ink discharge path connected to the plurality of individual ink discharge paths,
The plurality of nozzles and the plurality of pressure chambers form a row in a direction along two opposing outer surfaces of the head chip, and a plurality of the rows are provided in a direction perpendicular to the outer surface,
The common ink discharge path extends in a direction along the two outer surfaces;
The common ink discharge path is disposed only in one or both of the outermost regions adjacent to one of the outer surfaces and the central region between the two outer surfaces without passing through the row. Inkjet head.
The inkjet head according to claim 1, wherein the row is provided in three or more rows.
The inkjet head according to claim 1, wherein the rows are provided in even rows.
The common ink discharge path and the one common ink through the one line by the individual ink discharge path belonging to one row and provided between the two adjacent pressure chambers. The inkjet head according to any one of claims 1 to 3, wherein the pressure chambers belonging to another row disposed on the opposite side of the discharge path are connected.
The head chip includes, in order, a nozzle substrate provided with the plurality of nozzles, a flow path spacer substrate provided with the plurality of individual ink discharge paths, and a pressure chamber substrate provided with the plurality of pressure chambers. The inkjet head according to any one of claims 1 to 4, wherein the inkjet head is configured by being laminated.
The row is configured by alternately arranging the pressure chambers and air chambers isolated from the ink flow path,
The inkjet head according to claim 1, wherein the individual ink discharge path is disposed so as to overlap the air chamber when viewed in the axial direction of the nozzle.
The inkjet head according to any one of claims 1 to 6, wherein at least two of the individual ink discharge paths are provided in each of the plurality of pressure chambers.
The inkjet head according to any one of claims 1 to 7, wherein the common ink discharge path is arranged in both of the outermost regions.
The inkjet head according to any one of claims 1 to 8, wherein the common ink discharge path is disposed in the central region.
10. The ink jet head according to claim 9, wherein two common ink discharge paths are arranged in the central region without interposing the row.
An inkjet head according to any one of claims 1 to 10,
Ink supply means for generating a circulating flow from the pressure chamber to the individual ink discharge path;
An inkjet recording apparatus comprising: