JP7047840B2 - Inkjet head and inkjet recording device - Google Patents

Description

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

Conventionally, there is known an inkjet recording device that ejects ink stored in a pressure chamber from a plurality of nozzles provided in an inkjet head to form an image on a recording medium.
In such an inkjet recording device, bubbles generated in the inkjet head, foreign substances mixed in, and the like may clog the nozzles, causing problems such as injection defects. Further, depending on the type of ink, if the ink is left unused for a long period of time, the viscosity of the ink in the vicinity of the nozzle may increase due to sedimentation of ink particles, and it may be difficult to obtain stable ink ejection performance.

Therefore, there is known an inkjet head having a flow path in which the ink in the pressure chamber can be circulated in the head and capable of discharging air bubbles and foreign substances in the head together with the ink to the outside of the head (see, for example, Patent Document 1). ).
For example, Patent Document 1 discloses an inkjet head including an individual ink discharge path capable of discharging ink from each pressure chamber and a common ink discharge path in which a plurality of individual ink discharge paths merge, inside the head. Has been done.

Japanese Patent No. 5385975

In such an inkjet head, in order to facilitate the ejection of air bubbles, foreign substances, etc., the flow path resistance is reduced by increasing the cross-sectional area of the individual ink ejection passages, so that the ink can easily flow into the individual ink ejection passages. There is a need to. That is, it is necessary to increase the circulation flow rate.
However, it is necessary to increase the flow path resistance of the individual ink discharge paths so that the pressure wave (injection energy) at the time of ejecting the ink does not escape to the individual ink discharge paths.
There is a problem that the necessity of reducing the flow path resistance of the individual ink discharge path and the necessity of increasing the resistance are in conflict with each other.

The present invention has been made in view of such a problem, and an object of the present invention is to secure an ink discharge flow rate from a pressure chamber for effectively removing bubbles, foreign substances, etc. in the head chip together with ink. It is also possible to provide an inkjet head and an inkjet recording device capable of suppressing the escape of pressure waves from a pressure chamber to an individual ink discharge path.

In order to solve the above problems, the invention according to claim 1 is an inkjet head.
With multiple nozzles that eject ink,
A plurality of pressure chambers communicating with each of the plurality of nozzles and storing ink, and a plurality of pressure chambers.
A plurality of pressure generating means provided corresponding to each of the plurality of pressure chambers and applying pressure to the ink in the pressure chambers, and a plurality of pressure generating means.
A plurality of individual ink discharge passages that are branched from each of the plurality of pressure chambers and can discharge ink in the plurality of pressure chambers.
A common ink discharge path in which the plurality of individual ink discharge paths are connected is provided.
The individual ink discharge path is an enlarged flow path in which the flow path cross section gradually expands with the connection end with the pressure chamber as the minimum flow path cross section in the direction from the pressure chamber to the common ink discharge passage. It has and does not have a flow path that reduces the cross-sectional area of the flow path.

The invention according to claim 2 is an inkjet head.
With multiple nozzles that eject ink,
A plurality of pressure chambers communicating with each of the plurality of nozzles and storing ink, and a plurality of pressure chambers.
A plurality of pressure generating means provided corresponding to each of the plurality of pressure chambers and applying pressure to the ink in the pressure chambers, and a plurality of pressure generating means.
A plurality of individual ink discharge passages that are branched from each of the plurality of pressure chambers and can discharge ink in the plurality of pressure chambers.
A common ink discharge path in which the plurality of individual ink discharge paths are connected is provided.
The individual ink discharge passage has an enlarged flow path in which the cross-sectional area of the flow path expands in the direction from the pressure chamber to the common ink discharge passage, and at least two are provided in each of the plurality of pressure chambers. There is.

The invention according to claim 3 is the inkjet head according to claim 2 .
The expanded flow path has a throttle portion having a uniform flow path cross-sectional area over a predetermined length in the flow path central axis direction, and the opposite side of the throttle portion to the pressure chamber is the flow path cross-section from the throttle portion. Is expanding.

The invention according to claim 4 is the inkjet head according to claim 3 .
The throttle portion is continuous in contact with the pressure chamber.

The invention according to claim 5 is the inkjet head according to any one of claims 1 to 4 .
The expanded flow path has a tapered flow path in which the cross-sectional area of the flow path expands at a constant rate in the direction from the pressure chamber to the common ink discharge path.

The invention according to claim 6 is the inkjet head according to claim 5 .
The tapered flow path changes only in the cross-sectional width of the flow path in the axial direction of the nozzle.

The invention according to claim 7 is the inkjet head according to claim 6 .
The cross-sectional width of the flow path in the direction perpendicular to the axial direction of the nozzle at at least the connection end of the individual ink discharge path with the pressure chamber matches the width of the pressure chamber in the same direction.

The invention according to claim 8 is the inkjet head according to any one of claims 2 to 4 .
The individual ink discharge path has a throttle portion on the common ink discharge path side from the expanded flow path.

The invention according to claim 9 is the inkjet head according to any one of claims 1 to 8 .
The cross section of the minimum flow path on the upstream side of the enlarged flow path is connected to the pressure chamber.

The invention according to claim 10 is an inkjet recording apparatus.
The inkjet head according to any one of claims 1 to 9.
An ink supply means for generating a circulating flow from the pressure chamber to the individual ink discharge path, and an ink supply means.
To prepare for.

According to the present invention, it is possible to secure the ink discharge flow rate from the pressure chamber for effectively removing air bubbles and foreign matters in the head chip together with the ink, and to prevent the pressure wave from escaping from the pressure chamber to the individual ink discharge passage. It is possible to provide an inkjet head and an inkjet recording device that can be suppressed.

Schematic diagram showing an inkjet recording device Bottom view of the head unit Perspective view of the inkjet head Cross section of the inkjet head An exploded perspective view of the inkjet head An exploded perspective view of the head tip Top view of the pressure chamber board Bottom view of the pressure chamber board Plan view of the flow path spacer substrate Bottom view of the flow path spacer board Plan view of nozzle board Cross-sectional view of the head tip when cut with IXA-IXA Cross-sectional view of the head tip when cut with IXB-IXB Cross-sectional view of the head tip when cut with XA-XB Cross-sectional view of the head tip when cut with XA-XB Schematic diagram showing the ink circulation system A three-dimensional drawing of an example of a pressure chamber, a nozzle, and a first individual ink discharge path. A three-dimensional drawing of another example of the pressure chamber, nozzle, and first individual ink discharge path. A three-dimensional drawing of another example of the pressure chamber, nozzle, and first individual ink discharge path. A three-dimensional drawing of another example of the pressure chamber, nozzle, and first individual ink discharge path. A three-dimensional drawing of another example of the pressure chamber, nozzle, and first individual ink discharge path. A three-dimensional drawing of another example of the pressure chamber, nozzle, and first individual ink discharge path.

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, and the direction in which the recording medium is conveyed under the nozzle 111 is the front-back direction, and the left-right direction. The direction orthogonal to the front-back direction will be described as the vertical direction. In addition, the arrows in the flow path in the drawing indicate the direction in which the ink flows.

[Inkjet recording device]
As shown in FIG. 1, the inkjet recording apparatus 200 includes a paper feeding unit 210, an image recording unit 220, a paper ejection unit 230, an ink circulation system 8 (see FIG. 11) as an ink supply means, and the like. The inkjet 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 by the image recording unit 220, and discharges the recording medium M on which the image is formed. It is conveyed to the paper unit 230.

The paper feed unit 210 has a paper feed tray 211 for storing the recording medium M, and a medium supply unit 212 for transporting and supplying 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 whose inside is supported by two rollers, and the recording medium M is transferred from the paper feed tray 211 by rotating the rollers with the recording medium M placed on the belt. It is conveyed to the image recording unit 220.

The image recording unit 220 includes a transfer 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 transport drum 221 transports the recording medium M along the transport surface by rotating in the direction of the arrow in FIG. 1 while holding the recording medium M on the transport surface. Further, the transport drum 221 is provided with a claw portion and an intake portion (not shown), the end portion of the recording medium M is pressed by the claw portion, and the recording medium M is attracted to the transport surface by the intake portion on the transport surface. Holds the recording medium M in.

The delivery unit 222 is provided at a position between the medium supply unit 212 and the transfer drum 221 of the paper feed unit 210, and one end of the recording medium M transferred from the medium supply unit 212 is held by the swing arm unit 222a and picked up. , Delivery to the transfer drum 221 via 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 transfer drum 221 has a temperature within a predetermined temperature range. Heat M. The heating unit 223 has, for example, an infrared heater or the like, and energizes the infrared heater based on a control signal supplied from the control unit (not shown) to generate heat.

Based on the image data, the head unit 224 ejects ink to the recording medium M at an appropriate timing according to the rotation of the transport drum 221 holding the recording medium M to form an image. The head unit 224 is arranged with the ink ejection surface facing the transport drum 221 at a predetermined distance. In the inkjet recording apparatus 200 of the present embodiment, for example, four head units 224 corresponding to four colors of ink of yellow (Y), magenta (M), cyan (C), and black (K) are used as a recording medium M. They are arranged so as to be arranged at predetermined intervals in the order of Y, M, C, and K colors 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 the position of the transport drum 221 fixed with respect to the rotation axis when recording an image. That is, the inkjet recording device 200 is an inkjet recording device 200 that records an image in a one-pass drawing method using a line head.

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

The delivery unit 226 has a belt loop 226b having a ring-shaped belt whose inside is supported by two rollers, and a cylindrical transfer drum 226a that transfers the recording medium M from the transfer drum 221 to the belt loop 226b. The recording medium M delivered from the transfer drum 221 to the belt loop 226b by the transfer drum 226a is conveyed by the belt loop 226b and sent to the paper ejection unit 230.

The paper ejection unit 230 has a plate-shaped paper ejection 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, 4 and the like, the ink jet head 100 of the present embodiment is via a head chip 1, a wiring board 2 on which the head chip 1 is arranged, a wiring board 2, and a flexible substrate 3. The drive circuit board 4 connected to the circuit board 4, the manifold 5 for storing the ink supplied to the pressure chamber 131 in the head chip 1, the housing 6 in which the manifold 5 is housed inside, and the bottom opening of the housing 6 are closed. It includes a cap receiving plate 7 attached as described above, a cover member 9 attached to the housing 6, and the like.
In addition, in FIG. 3A, the illustration of the manifold 5 is omitted, and in FIGS. 3B and 4, the illustration of the cover member 9 is omitted.
Further, in the present embodiment, an example in which the number of rows of the nozzles 111 of the head chip 1 is four will be described, but the number of rows and arrangement of the nozzles 111 can be appropriately changed, for example, from one row to three rows. It may be any of them, and it may be 5 or more rows.

The head chip 1 is a substantially square columnar member that is long in the left-right direction, and is configured by sequentially laminating 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, 6B, etc.).
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, and has an inlet on the upper surface of the pressure chamber substrate 13 and an outlet on the lower surface. Further, the pressure chamber 131 communicates with the ink storage unit 51 at the upper end, ink is supplied to the pressure chamber 131 from the ink storage unit 51, and the ink is ejected from the nozzle 111 inside the pressure chamber 131. Ink for storage. Further, the pressure chamber 131 is formed along the vertical direction so as to straddle the pressure chamber substrate 13 and the flow path spacer substrate 12 and have a substantially rectangular cross section having the same area, and the end in the downward direction. The section communicates with the nozzle 111 (see FIGS. 9A, 9B, etc.).

The air chamber 132 has a substantially rectangular cross section slightly larger than the pressure chamber 131, and is formed so as to be parallel to the pressure chamber 131 along the vertical direction. Further, unlike the pressure chamber 131, the air chamber 132 does not communicate with the ink storage unit 51 so that ink does not flow into the air chamber 132. Further, the air chamber 132 is not communicated with the nozzle 111 (see FIGS. 9A, 9B, etc.).

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

Although it may be formed only by the pressure chamber 131 without providing the air chamber 132, it is preferable to provide the pressure chamber 131 and the air chamber 132 alternately as described above. As a result, 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, it can be prevented from affecting the other pressure chambers 131.

The common ink discharge path 133 is configured by connecting the first common ink discharge path 134 and the second common ink discharge path 135 (see FIGS. 5 and 6B, etc.).
The first common ink discharge path 134 is the front side, the rear side, and the central portion of the head chip 1 so as to avoid the portion where the pressure chamber 131 and the air chamber 132 are provided on the lower surface side of the pressure chamber substrate 13. In addition, three rows are arranged side by side along the left-right direction. Further, 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 path 123) are connected. ) Can be merged in the first common ink discharge path 134 (FIGS. 6B, 7A and 9A). Further, the first common ink discharge path 134 is connected to the second common ink discharge path 135 that can discharge ink to the outside of the head chip 1 near the right end portion. 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. Further, in the second common ink discharge path 135, the lower surface side of the pressure chamber substrate 13 communicates with the first common ink discharge path 134, and the upper surface side communicates with the discharge liquid chamber 57, and the first common ink discharge path It 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. Further, the second common ink discharge path 135 is provided near the right end portion of the head chip 1 and communicates with the first common ink discharge path 134. Further, the second common ink discharge path 135 is provided so as to have a larger volume than the individual pressure chambers 131, so that the ink discharge efficiency can be improved.

The flow path spacer substrate 12 is formed with a pressure chamber 131 and an individual ink discharge passage 121 branched from the pressure chamber 131 (FIGS. 5, 7A, 7B, 9A and FIGS. 9A). See 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 have a substantially rectangular cross section having the same area.

One end of the individual ink discharge passage 121 is connected to the pressure chamber 131, and the other end is connected to the first common ink discharge passage 134, so that the ink in the pressure chamber 131 is discharged to the first common ink discharge passage 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 the discharge of air bubbles, foreign substances, and the like together with the ink. Further, as shown in FIGS. 9A and 9B, for example, two individual ink discharge paths 121 may be provided, one in the front direction and one in the rear direction of the pressure chamber 131, so that bubbles, foreign substances, etc. can be introduced together with the ink. It is preferable because the effect of facilitating the discharge can be obtained and the production efficiency is high.

The individual ink discharge path 121 is configured by connecting the first individual ink discharge path 122 and the second individual ink discharge path 123. One end of the first individual ink discharge path 122 is connected to the pressure chamber 131, and the first individual ink discharge path 122 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.

The individual ink discharge passage 121 has an enlarged flow path in which the cross-sectional area of the flow path expands in the direction from the pressure chamber 131 to the common ink discharge passage 133. This is to secure the circulation flow rate and suppress the escape of the pressure wave from the pressure chamber 131 to the individual ink discharge passage 121. This will be described with reference to FIGS. 12 to 17. 12 to 17 are three-dimensional drawings of the pressure chamber 131, the nozzle 111, and the first individual ink discharge path 122, and each shows a different structure. Hereinafter, they will be described in order. Although one first individual ink discharge passage 122 connected to the pressure chamber 131 is shown as a representative, each of the plurality of first individual ink discharge passages 122 connected to the pressure chamber 131 may be implemented as having the same structure. preferable. In the pressure chamber 131, the portion formed on the pressure chamber substrate 13 is 131B, and the portion formed on the flow path spacer substrate 12 is 131A. The first individual ink discharge path 122 is connected to the pressure chamber 131A.

The first individual ink discharge passage 122 shown in FIG. 12 includes a throttle portion 122a having a uniform cross section connected to the pressure chamber 131, a tapered flow path 122b connected to the throttle portion 122a, and a uniform cross-section flow path 122c connected to the throttle portion 122a. The expanded flow path in which the cross-sectional area of the flow path expands in the direction from the pressure chamber 131 to the common ink discharge path 133 is composed of a throttle portion 122a having a uniform cross section and a tapered flow path 122b.
The throttle portion 122a having a uniform cross section is a flow path having a uniform cross-sectional area of the flow path over a predetermined length in the direction of the central axis of the flow path. Since the opposite side (downstream side) of the throttle portion 122a having a uniform cross section to the pressure chamber 131 is a tapered flow path 122b, the cross-sectional area of the flow path is larger than that of the throttle portion 122a, so that the expanded flow path (122a, 122b). Make up.
The throttle portion 122a is in contact with the pressure chamber 131 and is continuous. That is, the inlet of the individual ink discharge path 121 as viewed from the pressure chamber 131 is the throttle portion 122a.
The tapered flow path 122b expands the cross-sectional area of the flow path at a constant rate in the direction from the pressure chamber 131 to the common ink discharge path 133.

The narrowing portion 122a is narrowed only in the cross-sectional width of the flow path in the left-right direction. In the tapered flow path 122b, only the cross-sectional width of the flow path in the left-right direction changes. Here, the left-right direction is a direction perpendicular to the axial direction of the flow path center axis and the nozzle 111 in the first individual ink discharge path 122.
The cross section of the flow path of the throttle portion 122a coincides with the minimum cross section of the upstream side of the tapered flow path 122b, and the cross section of the maximum flow path on the downstream side of the tapered flow path 122b coincides with the cross section of the flow path of the uniform cross section 122c. The structure is such that the narrowing portion 122a, the tapered flow path 122b, and the uniform cross-sectional flow path 122c are continuous.

The first individual ink discharge path 122 shown in FIGS. 13 and 14 has a tapered flow path 122b. As shown in FIG. 13, the entire first individual ink discharge path 122 may be a tapered flow path 122b, or a part thereof may be a tapered flow path 122b as shown in FIG. In such a structure, the tapered flow path 122b is an enlarged flow path (122b).
As shown in FIG. 14, when the taper flow path 122b is used as a part, the upstream side minimum flow path cross section is connected to the pressure chamber 131, and the uniform cross section flow path 122c is connected to the downstream side maximum flow path cross section. This is to suppress the escape of the pressure wave from the pressure chamber 131 to the individual ink discharge passage 121.

In the first individual ink discharge path 122 shown in FIG. 15, the throttle portion 122a having a uniform cross section is formed thinly in the direction of the central axis of the flow path, and the throttle portion 122a having a uniform cross section is on the opposite side of the pressure chamber 131. A uniform cross-sectional flow path 122c having a larger cross-sectional area than the throttle portion 122a is connected to (downstream side). With such a structure, it is possible to effectively suppress the escape of the pressure wave from the pressure chamber 131 to the individual ink discharge passage 121.

The first individual ink discharge path 122 shown in FIG. 16 has an enlarged flow path composed of a throttle portion 122a having a uniform cross section at the upstream end portion and a tapered flow path 122b connected to the throttle portion 122a having a uniform cross section. However, the throttle portion 122e is provided on the common ink discharge path 133 side (downstream side) from the expanded flow path (122a, 122b). This suppresses the backflow of ink from the common ink discharge path 133.
In the structure shown in FIG. 16, the narrowing portion 122e has a uniform cross section, and a tapered flow path 122d having a reduced cross-sectional area of the flow path is provided on the upstream side thereof, but only the narrowing portion having a uniform cross section is provided. , Deformation such as using only a tapered flow path is possible.
Further, since the downstream throttle portion (122d, 122e) may be located downstream of the expansion flow path in the individual ink discharge path 121 and in front of the common ink discharge path 133, it may be located at the downstream end portion of the second individual ink discharge path 123. It may be provided.

The first individual ink discharge path 122 shown in FIG. 17 has a tapered flow path 122f. In the tapered flow path 122f, only the cross-sectional width of the flow path in the vertical direction changes. Here, the vertical direction is the axial direction of the nozzle 111.
By adopting the tapered flow path 122f in which only the cross-sectional width of the flow path in the vertical direction changes, the direction (horizontal direction) perpendicular to the axial direction of the nozzle 111 at least at the connection end of the individual ink discharge path 121 with the pressure chamber 131. The flow path cross-sectional width of 12 g coincides with the width of the pressure chamber 131 of 131 g in the same direction (left-right direction). As a result, the ink can flow from the pressure chamber 131 to the first individual ink discharge passage 122 in the same direction (left-right direction) without reducing the cross-sectional width of the flow path, so that bubbles and foreign substances in the pressure chamber 131 are discharged together with the ink. Easy to be done.
It should be noted that the tapered flow path 122f can be modified by limiting it to the upstream end portion of the first individual ink discharge path 122.

As described above, as described with reference to FIGS. 12 to 17, the inlet of the individual ink discharge passage 121 is narrowed when viewed from the pressure chamber 131, that is, the minimum cross section on the upstream side of the expanded flow path is connected to the pressure chamber 131. By doing so, it is possible to effectively suppress the escape of the pressure wave in the pressure chamber 131, the increase in the flow path resistance is also suppressed because the throttle portion is short, and the circulation flow rate by the ink circulation system 8 described later can be secured. Therefore, the ink At the same time, it is possible to effectively remove air bubbles and foreign substances in the head chip.

The first individual ink discharge path 122 of the present embodiment is provided on the lower surface side portion of the flow path spacer substrate 12 adjacent to the nozzle substrate 11, but the present invention is not limited to this. For example, the first individual ink discharge path 122 may be provided so as to straddle both the nozzle substrate 11 and the flow path spacer substrate 12, or may be provided only on the nozzle substrate 11, or the bottom surface of the flow path 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 arranged on the upper surface of the head chip 1, and two flexible boards 3 connected to the drive circuit board 4 are provided at both edges of the wiring board 2 along the front-rear direction. Are 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. The widths of the wiring board 2 in the left-right direction and the front-back direction are formed to be larger than those of the head chip 1.

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

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

Further, the lower end portion of the manifold 5 is attached and fixed to the outer edge portion of the wiring board 2 by adhesive. That is, the manifold 5 is arranged 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 and is provided above the pressure chamber 131 of the head tip 1 to store ink introduced into the pressure chamber 131. Specifically, as shown in FIG. 3B and the like, the manifold 5 is formed to be long in the left-right direction, and the hollow main body portion 52 constituting the ink storage portion 51 and the ink flow path are formed. It has 1st to 4th ink ports 53 to 56. Further, the ink storage unit 51 is divided into two sections, 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 upper end portion of the first liquid chamber 51a and is used for introducing ink into the ink storage portion 51. Further, a first joint 81a is extrapolated to the tip of the first ink port 53.
The second ink port 54 communicates with the upper left upper portion of the first liquid chamber 51a and is used to remove air bubbles in the first liquid chamber 51a. A second joint 81b is extrapolated to the tip of the second ink port 54.
The third ink port 55 communicates with the upper left upper portion of the second liquid chamber 51b and is used to remove air bubbles in the second liquid chamber 51b. Further, a third joint 82a is extrapolated to the tip of the third ink port 55.
The fourth ink port 56 communicates with the discharge liquid chamber 57 communicating with the second common ink discharge path 135 of the head chip 1, and the ink discharged from the head chip 1 is inkjet through the fourth ink port 56. It is discharged to the outside of the head 100.

The housing 6 is, for example, a member made of aluminum as a material and molded by a die-casting method, and is formed long in the left-right direction. Further, the housing 6 is formed so that the manifold 5 to which the head chip 1, the wiring board 2 and the flexible board 3 are attached can be housed inside, and the bottom surface of the housing 6 is open. Further, mounting holes 68 for mounting the housing 6 on the printer main body side are formed at both ends of the housing 6 in the left-right direction.

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

[Ink circulation system]
The ink circulation system 8 is an ink supply means for generating an ink circulation flow from the pressure chamber 131 in the inkjet head 100 to the individual ink discharge paths 121. The ink circulation system 8 is composed of 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 for supplying ink to the ink storage portion 51 of the manifold 5, and is connected to the first ink port 53 by the ink flow path 84.
The circulation sub-tank 82 is filled with 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.
Further, 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 (hereinafter, also referred to as “position reference surface”) of the head tip 1. As a result, the pressure P1 due to the head difference between the position reference surface and the supply sub-tank 81 and the pressure P2 due to the head difference between the position reference surface and the circulation sub-tank 82 are generated.
Further, the supply sub-tank 81 and the circulation sub-tank 82 are connected by an ink flow path 86. Then, the ink is 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 for supplying to the supply sub-tank 81, and is connected to the supply sub-tank 81 by an ink flow path 87. Then, 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. Then, the ink in the inkjet head 100 can be circulated at an appropriate circulation flow velocity by the pressure difference between the pressure P1 and the pressure P2. As a result, it is possible to remove air bubbles, foreign substances, etc. generated in the head chip 1 and suppress clogging of the nozzle 111, injection defects, and the like.

As an example of the ink circulation system 8, a method of controlling ink circulation by a head difference has been described, but it can be appropriately changed as long as it has a configuration capable of generating an ink circulation flow.

[others]
It should be considered that the embodiments of the present invention described above are exemplary in all respects 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, as the first individual ink discharge path 122 of the present embodiment, an example in which one of the flow path walls is formed by the nozzle substrate 11 is shown, but the present invention is not limited to this.

Further, 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 laminated in this order is shown, but the present invention is not limited to this, and the nozzle substrate 11 and the pressure chamber substrate 13 are not limited to this. It may have a two-layer structure. In this case, the individual ink discharge paths 121 may be provided on at least one of the nozzle substrate 11 and the pressure chamber substrate 13.

Further, although the share mode type example is shown as the inkjet head 100 of the present embodiment, it is not limited to this as long as a means for applying pressure to the ink in the pressure chamber 131 is provided.

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

Further, as the ink circulation system 8 of the present embodiment, an example in which the ink inside the head chip 1 is circulated is shown, but the ink in the second common ink discharge path 135 may be discharged without being circulated. It may be configured so that you can select whether to throw it away.

Further, as the head tip 1 of the present embodiment, an example of a straight type in which the pressure chamber 131 and the second common ink discharge path 135 are opened on the upper and lower surfaces of the head tip 1 is shown, but the present invention is not limited to this. For example, it may be configured to open on any side surface of the head chip 1 in the front-back and left-right directions, or may have a configuration having a bent portion in which the ink flow direction changes in the middle of the flow path.

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

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

Claims (10)

With multiple nozzles that eject ink,
A plurality of pressure chambers communicating with each of the plurality of nozzles and storing ink, and a plurality of pressure chambers.
A plurality of pressure generating means provided corresponding to each of the plurality of pressure chambers and applying pressure to the ink in the pressure chambers, and a plurality of pressure generating means.
A plurality of individual ink discharge passages that are branched from each of the plurality of pressure chambers and can discharge ink in the plurality of pressure chambers.
A common ink discharge path in which the plurality of individual ink discharge paths are connected is provided.
The individual ink discharge path is an enlarged flow path in which the flow path cross section gradually expands with the connection end with the pressure chamber as the minimum flow path cross section in the direction from the pressure chamber to the common ink discharge passage. An inkjet head that has and does not have a flow path that reduces the cross-sectional area of the flow path . With multiple nozzles that eject ink,
A plurality of pressure chambers communicating with each of the plurality of nozzles and storing ink, and a plurality of pressure chambers.
A plurality of pressure generating means provided corresponding to each of the plurality of pressure chambers and applying pressure to the ink in the pressure chambers, and a plurality of pressure generating means.
A plurality of individual ink discharge passages that are branched from each of the plurality of pressure chambers and can discharge ink in the plurality of pressure chambers.
A common ink discharge path in which the plurality of individual ink discharge paths are connected is provided.
The individual ink discharge passage has an enlarged flow path in which the cross-sectional area of the flow path expands in the direction from the pressure chamber to the common ink discharge passage, and at least two are provided in each of the plurality of pressure chambers. Inkjet head . The expanded flow path has a throttle portion having a uniform flow path cross-sectional area over a predetermined length in the flow path central axis direction, and the opposite side of the throttle portion to the pressure chamber is the flow path cross-sectional area from the throttle portion. The inkjet head according to claim 2 , wherein is expanded. The inkjet head according to claim 3 , wherein the throttle portion is continuous in contact with the pressure chamber. One of claims 1 to 4 , wherein the expanded flow path has a tapered flow path in which the cross-sectional area of the flow path expands at a constant rate in the direction from the pressure chamber to the common ink discharge path. Inkjet head described in. The inkjet head according to claim 5 , wherein the tapered flow path changes only the cross-sectional width of the flow path in the axial direction of the nozzle. The sixth aspect of claim 6 , wherein the cross-sectional width of the flow path in the direction perpendicular to the axial direction of the nozzle at at least the connection end of the individual ink discharge path with the pressure chamber matches the width of the pressure chamber in the same direction. Inkjet head. The inkjet head according to any one of claims 2 to 4 , wherein the individual ink discharge path has a throttle portion on the common ink discharge path side from the expanded flow path. The inkjet head according to any one of claims 1 to 8 , wherein the minimum flow path cross section on the upstream side of the enlarged flow path is connected to the pressure chamber. The inkjet head according to any one of claims 1 to 9.
An ink supply means for generating a circulating flow from the pressure chamber to the individual ink discharge path, and an ink supply means.
Inkjet recording device equipped with.

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