JP6992595B2 - Liquid discharge head and liquid discharge device - Google Patents

Description

The present invention relates to a technique for ejecting a liquid such as ink.

A liquid discharge head is known in which a liquid such as ink in a pressure chamber is discharged from a nozzle by causing a pressure change in the pressure chamber by a drive element such as a piezoelectric element. In such a liquid discharge head, bubbles may be mixed in the liquid or the liquid may be thickened, which may cause a nozzle discharge failure. For example, in Patent Document 1, a circulation flow path (supply branch flow path and recovery branch flow path) is arranged below the pressure chamber, and the pressure chamber and the nozzle are separated from each other (first recovery throttle flow path, second recovery flow path). (Recovery throttle flow path) communicates with the circulation flow path. As a result, the thickening of the liquid is suppressed by forming a flow of the liquid that circulates through the circulation flow path.

JP-A-2016-107495

However, when the circulation flow path is communicated with the pressure chamber or the nozzle by a plurality of flow paths as in Patent Document 1, the flow path resistance of each flow path communicating with the circulation flow path does not change, and the circulation flow path is not changed. Even if the liquid is circulated through the communication, the liquid will flow in the same way in each flow path. Therefore, when the liquid is settled or thickened, it becomes difficult for foreign matter or the thickened liquid due to the settling to be discharged from the vicinity of the nozzle to the circulation flow path.

In order to solve the above problems, the liquid discharge head according to the preferred embodiment of the present invention includes a nozzle plate provided with a nozzle, a pressure chamber to which the liquid is supplied, and a communication passage connecting the pressure chamber to the nozzle. , A flow path forming part provided with a circulating liquid chamber, a pressure generating part for generating a pressure change in the pressure chamber, a first circulation passage connecting the pressure chamber to the circulating liquid chamber, and a communication passage in the circulating liquid chamber. It is provided with a second circulation path to communicate with, and the flow path resistance of the second circulation path is smaller than the flow path resistance of the first circulation path.

It is a block diagram of the liquid discharge device in 1st Embodiment of this invention. It is sectional drawing of the liquid discharge head. It is a partial exploded perspective view of a liquid discharge head. It is sectional drawing of the piezoelectric element. It is explanatory drawing of the circulation of ink in a liquid ejection head. It is a plan view and a cross-sectional view of the vicinity of a circulating liquid chamber in a liquid discharge head. It is sectional drawing of the vicinity of the circulation liquid chamber in the liquid discharge head of the 1st modification. It is sectional drawing of the vicinity of the circulation liquid chamber in the liquid discharge head of the 2nd modification. It is sectional drawing of the liquid discharge head of 2nd Embodiment. It is sectional drawing of the liquid discharge head of 3rd Embodiment. It is sectional drawing of the liquid discharge head of 4th Embodiment. It is sectional drawing of the liquid discharge head of the 3rd modification.

<First Embodiment>
FIG. 1 is a configuration diagram illustrating the liquid discharge device 100 according to the first embodiment of the present invention. The liquid ejection device 100 of the first embodiment is an inkjet printing apparatus that ejects ink, which is an example of a liquid, onto a medium 12. The medium 12 is typically printing paper, but the medium 12 may be a printing target of any material such as a resin film or a cloth. As shown in FIG. 1, a liquid container 14 for storing ink is installed in the liquid ejection device 100. For example, a cartridge that can be attached to and detached from the liquid ejection device 100, a bag-shaped ink pack made of a flexible film, or an ink tank that can be refilled with ink is used as the liquid container 14. A plurality of types of ink having different colors are stored in the liquid container 14. The ink may be a dye ink containing a dye as a coloring material or a pigment ink containing a pigment as a coloring material.

As shown in FIG. 1, the liquid discharge device 100 includes a control unit 20, a transfer mechanism 22, a moving mechanism 24, and a liquid discharge head 26. The control unit 20 includes, for example, a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and controls each element of the liquid discharge device 100 in an integrated manner. The transport mechanism 22 transports the medium 12 in the Y direction under the control of the control unit 20.

The moving mechanism 24 reciprocates the liquid discharge head 26 in the X direction under the control of the control unit 20. The X direction is a direction that intersects (typically orthogonally) the Y direction in which the medium 12 is conveyed. The moving mechanism 24 of the first embodiment includes a substantially box-shaped carriage 242 (conveyor body) for accommodating the liquid discharge head 26, and a transport belt 244 to which the carriage 242 is fixed. A plurality of liquid discharge heads 26 may be mounted on the carriage 242, or a liquid container 14 may be mounted on the carriage 242 together with the liquid discharge head 26.

The liquid discharge head 26 discharges the ink supplied from the liquid container 14 from the plurality of nozzles N (discharge holes) to the medium 12 under the control of the control unit 20. Each liquid ejection head 26 ejects ink to the medium 12 in parallel with the transfer of the medium 12 by the transport mechanism 22 and the repetitive reciprocation of the carriage 242, whereby a desired image is formed on the surface of the medium 12. The direction perpendicular to the XY plane (for example, a plane parallel to the surface of the medium 12) is hereinafter referred to as the Z direction. The ink ejection direction (typically the vertical direction) by each liquid ejection head 26 corresponds to the Z direction.

As shown in FIG. 1, a plurality of nozzles N of the liquid discharge head 26 are arranged in the Y direction. The plurality of nozzles N of the first embodiment are divided into a first nozzle row L1 and a second nozzle row L2 arranged side by side at intervals in the X direction. Each of the first nozzle row L1 and the second nozzle row L2 is a set of a plurality of nozzles N linearly arranged in the Y direction. Although it is possible to make the positions of the nozzles N different in the Y direction between the first nozzle row L1 and the second nozzle row L2 (that is, staggered arrangement or stagger arrangement), the first nozzle row L1 and the first The configuration in which the positions of the nozzles N in the Y direction are matched with those of the two nozzle rows L2 will be illustrated below for convenience. In the liquid discharge head 26, a plane parallel to the YY plane is referred to as a virtual plane O.

FIG. 2 is a cross-sectional view when the liquid discharge head 26 is cut in a cross section perpendicular to the Y direction, and FIG. 3 is a partially exploded perspective view of the liquid discharge head 26. As shown in FIGS. 2 and 3, the liquid discharge head 26 of the first embodiment has elements related to each nozzle N (exemplification of the first nozzle) of the first nozzle row L1 and each nozzle of the second nozzle row L2. The elements related to N (exemplification of the second nozzle) are arranged symmetrically with the virtual surface O interposed therebetween. That is, the portion of the liquid discharge head 26 on the positive side in the X direction (hereinafter referred to as the "first portion") P1 and the portion on the negative side in the X direction (hereinafter referred to as the "second portion") P2 with the virtual surface O interposed therebetween. The structure is practically the same. The plurality of nozzles N of the first nozzle row L1 are formed in the first portion P1, and the plurality of nozzles N of the second nozzle row L2 are formed in the second portion P2. The virtual surface O corresponds to the boundary surface between the first portion P1 and the second portion P2.

As shown in FIGS. 2 and 3, the liquid discharge head 26 includes a flow path forming portion 30. The flow path forming portion 30 is a structure for forming a flow path for supplying ink to a plurality of nozzles N. The flow path forming portion 30 of the first embodiment is composed of a stack of a communication plate 32 and a pressure chamber forming plate 34 (pressure chamber forming plate). Each of the communication plate 32 and the pressure chamber forming plate 34 is a plate-shaped member elongated in the Y direction. A pressure chamber forming plate 34 is installed on the surface Fa on the negative side in the Z direction of the communication plate 32, for example, by using an adhesive.

As shown in FIG. 2, in addition to the pressure chamber forming plate 34, a vibrating portion 42, a plurality of piezoelectric elements 44, a protective member 46, and a housing portion 48 are installed on the surface Fa of the communication plate 32. (Not shown in FIG. 3). On the other hand, the nozzle plate 52 and the vibration absorbing body 54 are installed on the surface Fb on the positive side (that is, the side opposite to the surface Fa) in the Z direction of the communication plate 32. Each element of the liquid discharge head 26 is generally a plate-shaped member elongated in the Y direction similar to the communication plate 32 and the pressure chamber forming plate 34, and is joined to each other by using, for example, an adhesive. The direction in which the communication plate 32 and the pressure chamber forming plate 34 are laminated and the direction in which the communication plate 32 and the nozzle plate 52 are laminated (or the direction perpendicular to the surface of each plate-shaped element) are grasped as the Z direction. It is also possible.

The nozzle plate 52 is a plate-shaped member in which a plurality of nozzles N are formed, and is installed on the surface Fb of the communication plate 32 using, for example, an adhesive. Each of the plurality of nozzles N is a cylindrical through hole through which ink is passed. The nozzle plate 52 of the first embodiment is formed with a plurality of nozzles N constituting the first nozzle row L1 and a plurality of nozzles N constituting the second nozzle row L2. Specifically, a plurality of nozzles N of the first nozzle row L1 are formed along the Y direction in the region of the nozzle plate 52 on the positive side in the X direction when viewed from the virtual surface O, and the region on the negative side in the X direction. In addition, a plurality of nozzles N of the second nozzle row L2 are formed along the Y direction. The nozzle plate 52 of the first embodiment is a single plate-shaped member that is continuous over a portion of the first nozzle row L1 in which a plurality of nozzles N are formed and a portion of the second nozzle row L2 in which a plurality of nozzles N are formed. Is. The nozzle plate 52 of the first embodiment is manufactured by processing a single crystal substrate of silicon (Si) by utilizing semiconductor manufacturing techniques such as dry etching and wet etching. However, a known material or manufacturing method may be arbitrarily adopted for manufacturing the nozzle plate 52.

As shown in FIGS. 2 and 3, the communication plate 32 is formed with a space Ra, a plurality of supply paths 61, and a plurality of communication passages 63 for each of the first portion P1 and the second portion P2. The space Ra is an opening formed in a long shape along the Y direction (when viewed from the Z direction) in a plan view, and the supply passage 61 and the communication passage 63 are through holes formed for each nozzle N. The plurality of communication passages 63 are arranged in the Y direction in a plan view, and the plurality of supply paths 61 are arranged in the Y direction between the arrangement of the plurality of communication passages 63 and the space Ra. The plurality of supply paths 61 commonly communicate with the space Ra. Further, any one communication passage 63 overlaps the nozzle N corresponding to the communication passage 63 in a plan view. Specifically, any one communication passage 63 of the first portion P1 communicates with one nozzle N corresponding to the communication passage 63 in the first nozzle row L1. Similarly, any one communication passage 63 of the second portion P2 communicates with one nozzle N corresponding to the communication passage 63 in the second nozzle row L2.

As shown in FIGS. 2 and 3, the pressure chamber forming plate 34 is a plate-shaped member in which a plurality of pressure chambers C (cavities) are formed for each of the first portion P1 and the second portion P2. The plurality of pressure chambers C are arranged in the Y direction. Each pressure chamber C is a rectangular space formed for each nozzle N and long along the X direction in a plan view. Specifically, each pressure chamber C is defined by two side surfaces parallel to the YY plane and an upper surface (ceiling surface) parallel to the XY plane.

The communication plate 32 and the pressure chamber forming plate 34 are manufactured by processing a single crystal substrate of silicon by using, for example, a semiconductor manufacturing technique, similarly to the nozzle plate 52 described above. However, known materials and manufacturing methods can be arbitrarily adopted for manufacturing the communication plate 32 and the pressure chamber forming plate 34. The flow path forming portion 30 (communication plate 32 and pressure chamber forming plate 34) and the nozzle plate 52 in the first embodiment include a substrate made of silicon. Therefore, for example, by using the semiconductor manufacturing technology as in the above-mentioned example, there is an advantage that a fine flow path can be formed in the flow path forming portion 30 and the nozzle plate 52 with high accuracy.

As shown in FIG. 2, a vibrating portion 42 is installed on the surface of the pressure chamber forming plate 34 opposite to the communication plate 32. The vibrating portion 42 of the first embodiment is a plate-shaped member (diaphragm) that can elastically vibrate. The pressure chamber forming plate 34 and the vibrating portion 42 are integrally formed by selectively removing a part of the plate-shaped member having a predetermined plate thickness in the plate thickness direction in the region corresponding to the pressure chamber C. It is also possible.

The surface Fa of the communication plate 32 and the vibrating portion 42 face each other with a gap inside each pressure chamber C. The pressure chamber C is a space located between the surface Fa of the communication plate 32 and the vibrating portion 42, and causes a pressure change in the ink filled in the space. Each pressure chamber C is, for example, a space whose longitudinal direction is the X direction, and is individually formed for each nozzle N. A plurality of pressure chambers C are arranged in the Y direction for each of the first nozzle row L1 and the second nozzle row L2. As shown in FIGS. 2 and 3, the end of any one pressure chamber C closer to the virtual surface O overlaps the communication passage 63 in a plan view, and the end farther from the virtual surface O is a plane. It visually overlaps the supply path 61. Therefore, in each of the first portion P1 and the second portion P2, the pressure chamber C communicates with the nozzle N via the communication passage 63 and also communicates with the space Ra via the supply path 61. It is also possible to add a predetermined flow path resistance by forming a throttle flow path having a narrowed flow path cross-sectional area in the pressure chamber C.

As shown in FIG. 2, on the surface of the vibrating portion 42 opposite to the pressure chamber C, for each of the first portion P1 and the second portion P2, a plurality of piezoelectric elements 44 corresponding to different nozzles N 44. Is installed. The piezoelectric element 44 is a passive element that is deformed by the supply of a drive signal. The plurality of piezoelectric elements 44 are arranged in the Y direction so as to correspond to each pressure chamber C.

As shown in FIG. 4, any one piezoelectric element 44 is a driving element in which a piezoelectric layer 443 is interposed between the first electrode 441 and the second electrode 442 facing each other. It is also possible to use one of the first electrode 441 and the second electrode 442 as a continuous electrode (that is, a common electrode) across the plurality of piezoelectric elements 44. The portion where the first electrode 441, the second electrode 442, and the piezoelectric layer 443 overlap in a plan view functions as the piezoelectric element 44. It is also possible to define the portion deformed by the drive signal supplied from the wiring board 28 (that is, the active portion that vibrates the vibrating portion 42) as the piezoelectric element 44. As described above, the piezoelectric element 44 of the present embodiment functions as a pressure generating unit that generates a pressure change in the pressure chamber C.

The plurality of piezoelectric elements 44 are divided into a first piezoelectric element and a second piezoelectric element. For example, the first piezoelectric element is a plurality of piezoelectric elements 44 arranged on one side in the X direction (for example, the right side in FIG. 2) when viewed from the virtual surface O. The second piezoelectric element is a plurality of piezoelectric elements 44 arranged on the other side (for example, the left side in FIG. 2) in the X direction when viewed from the virtual surface O. When the vibrating portion 42 vibrates in conjunction with the deformation of the piezoelectric element 44, the pressure in the pressure chamber C fluctuates, so that the ink filled in the pressure chamber C passes through the communication passage 63 and the nozzle N and is ejected. To.

The protective member 46 of FIG. 2 is a plate-shaped member for protecting a plurality of piezoelectric elements 44, and is installed on the surface of the vibrating portion 42 (or the surface of the pressure chamber forming plate 34). The material and manufacturing method of the protective member 46 are arbitrary, but like the communication plate 32 and the pressure chamber forming plate 34, the protective member 46 is formed by processing, for example, a silicon (Si) single crystal substrate by semiconductor manufacturing technology. obtain. A plurality of piezoelectric elements 44 are housed in a recess formed on the surface of the protective member 46 on the vibrating portion 42 side.

The end portion of the wiring board 28 is joined to the surface of the vibrating portion 42 on the side opposite to the flow path forming portion 30 (or the surface of the flow path forming portion 30). The wiring board 28 is a flexible mounting component in which a plurality of wirings (not shown) for electrically connecting the control unit 20 and the liquid discharge head 26 are formed. Of the wiring board 28, the end portion extending to the outside through the opening formed in the protective member 46 and the opening formed in the housing portion 48 is connected to the control unit 20. For example, a flexible wiring board 28 such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable) is preferably adopted.

The housing portion 48 is a case for storing ink supplied to a plurality of pressure chambers C (further, a plurality of nozzles N). The surface of the housing portion 48 on the positive side in the Z direction is joined to the surface Fa of the communication plate 32 with, for example, an adhesive. A known technique or manufacturing method can be arbitrarily adopted for manufacturing the housing portion 48. For example, the housing portion 48 can be formed by injection molding of a resin material.

In the housing portion 48 of the first embodiment, a space Rb is formed for each of the first portion P1 and the second portion P2. The space Rb of the housing portion 48 and the space Ra of the communication plate 32 communicate with each other. The space composed of the space Ra and the space Rb functions as a liquid storage chamber R (reservoir) for storing ink supplied to the plurality of pressure chambers C. The liquid storage chamber R is a common liquid chamber shared by the plurality of nozzles N. A liquid storage chamber R is formed in each of the first portion P1 and the second portion P2. The liquid storage chamber R of the first portion P1 is located on the positive side in the X direction with respect to the virtual surface O, and the liquid storage chamber R of the second portion P2 is located on the negative side in the X direction with respect to the virtual surface O. An introduction port 482 for introducing the ink supplied from the liquid container 14 into the liquid storage chamber R is formed on the surface of the housing portion 48 on the side opposite to the communication plate 32.

A vibration absorber 54 is installed on the surface Fb of the communication plate 32 for each of the first portion P1 and the second portion P2. The vibration absorber 54 is a flexible film (compliance substrate) that absorbs pressure fluctuations of ink in the liquid storage chamber R. As shown in FIG. 3, the vibration absorbing body 54 is installed on the surface Fb of the communicating plate 32 so as to block the space Ra of the communicating plate 32 and the plurality of supply paths 61, and the wall surface of the liquid storage chamber R (specifically). Consists of the bottom).

A space constituting the circulating liquid chamber 65 is formed on the surface Fb of the communication plate 32 facing the nozzle plate 52. The circulating liquid chamber 65 of the first implementation liquid is a long groove-shaped bottomed hole extending in the Y direction in a plan view. The opening of the circulating liquid chamber 65 is closed by the nozzle plate 52 joined to the surface Fb of the communication plate 32.

FIG. 5 is a block diagram of the liquid discharge head 26 focusing on the circulating liquid chamber 65. As shown in FIG. 5, the circulating liquid chamber 65 is continuous over a plurality of nozzles N along the first nozzle row L1 and the second nozzle row L2. Specifically, the circulating liquid chamber 65 is formed between the arrangement of the plurality of nozzles N in the first nozzle row L1 and the arrangement of the plurality of nozzles N in the second nozzle row L2. Therefore, as shown in FIG. 2, the circulating liquid chamber 65 is located between the communication passage 63 of the first portion P1 and the communication passage 63 of the second portion P2.

As described above, the plurality of pressure chambers C and the plurality of piezoelectric elements 44 are arranged in the Y direction in each of the first portion P1 and the second portion P2. Therefore, it can be paraphrased that the circulating fluid chamber 65 extends in the Y direction so as to be continuous over the plurality of pressure chambers C or the plurality of piezoelectric elements 44 in each of the first portion P1 and the second portion P2. Further, as shown in FIGS. 2 and 3, the circulating liquid chamber 65 and the liquid storage chamber R extend in the Y direction with a mutual interval, and the pressure chamber C, the communication passage 63, and the nozzle N are within the interval. It is also possible that and is located.

As described above, the flow path forming portion 30 of the first embodiment includes the pressure chamber C (exemplification of the first pressure chamber) and the communication passage 63 (exemplification of the first communication passage) in the first portion P1 and the second portion P2. Circulation located between the pressure chamber C (exemplification of the second pressure chamber) and the communication passage 63 (exemplification of the second communication passage) and the communication passage 63 of the first portion P1 and the communication passage 63 of the second portion P2. It is a structure in which the liquid chamber 65 is formed. Further, as shown in FIG. 2, the flow path forming portion 30 of the first embodiment includes a partition wall portion 69 that partitions between the circulating liquid chamber 65 and each communication passage 63.

FIG. 6 is an enlarged plan view and cross-sectional view of a portion of the liquid discharge head 26 in the vicinity of the circulating liquid chamber 65. As shown in FIG. 6, a plurality of first circulation passages 71 for communicating the pressure chamber C with the circulating liquid chamber 65 are formed on the surface of the pressure chamber forming plate 34 facing the communication plate 32. A plurality of first circulation paths 71 are arranged for each of the first portion P1 and the second portion P2. The plurality of first circulation passages 71 of the first portion P1 correspond one-to-one to the plurality of pressure chambers C of the first nozzle row L1. Further, the plurality of first circulation passages 71 of the second portion P2 correspond one-to-one to the plurality of pressure chambers C of the second nozzle row L2.

On the surface of the nozzle plate 52 facing the flow path forming portion 30, a plurality of second circulation paths 72 that communicate the communication passage 63 with the circulating liquid chamber 65 are formed. A plurality of second circulation paths 72 are arranged for each of the first portion P1 and the second portion P2. The plurality of second circulation paths 72 of the first portion P1 correspond one-to-one with the plurality of communication passages 63 of the first nozzle row L1. Further, the plurality of second circulation paths 72 of the second portion P2 correspond one-to-one to the plurality of communication passages 63 of the second nozzle row L2.

Each of the first circulation path 71 and the second circulation path 72 is a groove portion (that is, a long bottomed hole) extending in the X direction, and functions as a flow path for ink to flow. The first circulation path 71 and the second circulation path 72 are formed on the circulating liquid chamber 65 side when viewed from the nozzle N in a plan view, away from the nozzle N. Since the plurality of first circulation passages 71 and the plurality of pressure chambers C are arranged in the pressure chamber forming plate 34, for example, the plurality of first circulation passages 71 and the plurality of pressure chambers C are collectively combined in a common process by semiconductor manufacturing technology. Can be formed Since the plurality of second circulation paths 72 and the plurality of nozzles N are arranged on the nozzle plate 52, for example, the plurality of first circulation paths 71 and the plurality of nozzles N can be collectively formed by a common process by semiconductor manufacturing technology. ..

As shown in FIG. 5, the liquid discharge device 100 of the first embodiment includes a circulation mechanism 75. The circulation mechanism 75 is a mechanism for returning the ink in the circulating liquid chamber 65 to the liquid storage chamber R and circulating the ink. The circulation mechanism 75 of the first embodiment has, for example, a suction mechanism (for example, a pump) that sucks ink from the circulating liquid chamber 65, a filter mechanism that collects bubbles and foreign substances mixed in the ink, and thickening by heating the ink. It is provided with a heating mechanism for reducing the amount of ink (not shown). Ink from which air bubbles and foreign substances are removed by the circulation mechanism 75 and whose thickening is reduced is supplied from the circulation mechanism 75 to the liquid storage chamber R via the introduction port 482. According to such a circulation mechanism 75, the ink circulates through the route of liquid storage chamber R → supply passage 61 → pressure chamber C → first circulation passage 71 → circulation liquid chamber 65 → circulation mechanism 75 → liquid storage chamber R. Ink is also circulated through the route of liquid storage chamber R → supply passage 61 → pressure chamber C → communication passage 63 → second circulation passage 72 → circulation liquid chamber 65 → circulation mechanism 75 → liquid storage chamber R.

As shown in FIG. 5, the circulation mechanism 75 of the first embodiment sucks ink from both sides of the circulation liquid chamber 65 in the Y direction. That is, the circulation mechanism 75 sucks ink from the vicinity of the negative end of the circulating liquid chamber 65 in the Y direction and the vicinity of the positive end of the circulating liquid chamber 65 in the Y direction. In the configuration in which ink is sucked from only one end of the circulating liquid chamber 65 in the Y direction, a difference in ink pressure occurs between both ends of the circulating liquid chamber 65, and the pressure difference in the circulating liquid chamber 65 becomes Therefore, the pressure of the ink in the communication passage 63 may differ depending on the position in the Y direction. Therefore, the ink ejection characteristics (for example, ejection amount and ejection speed) from each nozzle N may differ depending on the position in the Y direction. In contrast to the above configuration, in the first embodiment, since the ink is sucked from both sides of the circulating liquid chamber 65, the pressure difference inside the circulating liquid chamber 65 is reduced. Therefore, it is possible to approximate the ink ejection characteristics with high accuracy over a plurality of nozzles N arranged in the Y direction. However, if the pressure difference in the Y direction in the circulating liquid chamber 65 does not pose a particular problem, the ink may be sucked from one end of the circulating liquid chamber 65.

According to the first embodiment having the above configuration, when the pressure in the pressure chamber C fluctuates due to the operation of the piezoelectric element 44 shown in FIG. 6, a part of the ink flowing from the pressure chamber C to the communication passage 63 is discharged. It is discharged from the nozzle N to the outside, and the remaining part flows into the circulating liquid chamber 65. At this time, in the first embodiment, not only the flow flowing from the communication passage 63 to the circulating liquid chamber 65 through the second circulation passage 72 (the flow of the thick broken line arrow in FIG. 6), but also the flow from the pressure chamber C to the first circulation passage. A flow flowing into the circulating liquid chamber 65 via the 71 (flow of the thin broken line arrow in FIG. 6) is also generated. As a result, not only the communication passage 63 but also the bubbles and the thickened ink that have entered the pressure chamber C can be discharged to the circulating liquid chamber 65, so that the ejection failure of the nozzle N can be effectively suppressed.

By the way, if the flow path resistance of the first circulation path 71 communicating with the circulation liquid chamber 65 and the flow path resistance of the second circulation passage 72 are almost the same, even if the ink is circulated through the circulation liquid chamber 65. , Ink flows in the first circulation path 71 and the second circulation path 72 in the same manner. Therefore, when ink settles or thickens in the communication passage 63, foreign matter or thickened ink due to the settling is difficult to be discharged to the circulating liquid chamber 65.

Therefore, in the first embodiment, the flow path resistance of the second circulation path 72 is set to be smaller than the flow path resistance of the first circulation path 71. This makes it easier for ink to flow from the second circulation passage 72 to the circulation liquid chamber 65 than to the first circulation passage 71. Therefore, foreign matter and thickening ink due to sedimentation of ink that tends to accumulate in the vicinity of the nozzle N are easily discharged from the second circulation path 72 into the circulating liquid chamber 65, so that foreign matter and thickening ink can be efficiently discharged.

When an ink (for example, pigment ink) in which foreign matter is easily generated due to sedimentation is used, when the foreign matter is generated, it falls downward in the vertical direction, so that the foreign matter tends to collect in the vicinity of the nozzle N in the communication passage 63. Further, the ink containing a solvent having a higher volatility than water tends to thicken, and the meniscus in the nozzle N, which is the gas-liquid interface between the ink and air, tends to dry. Therefore, in the vicinity of the nozzle N in the communication passage 63. Ink thickening tends to proceed. In this respect, according to the first embodiment, the ink flows more easily in the second circulation passage 72 near the nozzle N than in the first circulation passage 71 near the pressure chamber C, so that the nozzle N in the communication passage 63 Foreign matter accumulated in the vicinity and thickened ink are also easily discharged from the second circulation path 72 to the circulating liquid chamber 65 along with the ink flow.

The flow path cross-sectional area of the second circulation path 72 is larger than the flow path cross-sectional area of the first circulation path 71. Specifically, the flow path width W2 in the Y direction of the second circulation path 72 shown in FIG. 6 is larger than the flow path width W1 (dimension in the Y direction) in the Y direction of the first circulation path 71. Further, the flow path height H2 in the Z direction of the second circulation path 72 is larger than the flow path height H1 in the Z direction of the first circulation path 71. In this way, by making the flow path width W2 and the flow path height H2 of the second circulation path 72 larger than the flow path width W1 and the flow path height H1 of the first circulation path 71, the second circulation path 72 The cross-sectional area of the flow path of the first circulation path 71 can be made larger than the cross-sectional area of the flow path of the first circulation path 71. The flow path height H1 and the flow path height H2 are constant over the entire length in the X direction, respectively.

According to the above configuration, the flow path resistance of the second circulation path 72 can be made smaller than the flow path resistance of the first circulation path 71. Therefore, since the ink flows more easily in the second circulation path 72 than in the first circulation path 71, foreign matter and thickened ink accumulated in the vicinity of the nozzle N in the communication passage 63 can be removed through the second circulation path 72. It can be efficiently discharged to the circulating liquid chamber 65 through the circulation liquid chamber 65. The flow path length D2 in the X direction of the second circulation path 72 may be shorter than the flow path length D1 in the X direction of the first circulation path 71. Also with this configuration, the flow path resistance of the second circulation path 72 can be made smaller than the flow path resistance of the first circulation path 71.

The flow path cross-sectional area of the nozzle N of the first embodiment (cross-sectional area perpendicular to the Z direction) is larger than the flow path cross-sectional area of the first circulation path 71 (cross-sectional area perpendicular to the X direction). It is large and larger than the flow path cross-sectional area of the second circulation path 72 (cross-sectional area perpendicular to the X direction). Specifically, as shown in FIG. 6, by making the inner diameter Nw of the nozzle N larger than the flow path width W1 in the Y direction of the first circulation path 71, the flow path cross-sectional area of the nozzle N is increased by the first circulation path 71. It should be larger than the cross-sectional area of the flow path. Further, by making the inner diameter Nw of the nozzle N larger than the flow path width W2 in the Y direction of the second circulation path 72, the flow path cross-sectional area of the nozzle N is made larger than the flow path cross-sectional area of the second circulation path 72. ..

According to the above configuration, the flow path resistance of the nozzle N can be made smaller than the flow path resistance of the first circulation path 71 and smaller than the flow path resistance of the second circulation path 72. Therefore, when the ink is ejected, the ink can be more easily flowed to the nozzle N than the first circulation path 71 and the second circulation path 72, so that the amount of ink ejected from the nozzle N can be increased. As shown in FIG. 6, the flow path length Nd of the nozzle N in the Y direction is shorter than the flow path length D1 of the first circulation path 71 in the X direction, and the flow path in the X direction of the second circulation path 72. It may be made shorter than the length D2. Also with this configuration, the flow path resistance of the nozzle N can be made smaller than the flow path resistance of the first circulation path 71 and smaller than the flow path resistance of the second circulation path 72.

The pressure chamber C and the first circulation passage 71 of the first embodiment are arranged as follows. That is, the pressure chamber C extends in the second direction along the plane orthogonal to the first direction. The first circulation path 71 extends from the pressure chamber C (when viewed from the Z direction) in a plan view, and extends in a direction intersecting the first direction. The first direction is a reference direction between the extending direction of the pressure chamber C and the extending direction of the first circulation passage 71, and is exemplified as the Z direction in the present embodiment. The second direction is a direction along an XY plane orthogonal to the Z direction, which is an example of the first direction, and is exemplified as the X direction in the present embodiment. Although the case where the first direction (Z direction) of the present embodiment is the vertical direction is exemplified, the first direction does not have to be the vertical direction.

According to such a configuration, the direction in which the first circulation path 71 extends can be aligned with the direction in which the pressure chamber C extends. Therefore, when the flow from the pressure chamber C to the first circulation passage 71 is formed, the direction of the ink flow through the first circulation passage 71 and the direction of the ink flow in the pressure chamber C do not change significantly. That is, the flow from the pressure chamber C to the first circulation flow path 71 can be formed at an angle smaller than 90 degrees.

Therefore, since the direction of the ink flow through the first circulation path 71 and the direction of the ink flow in the pressure chamber C can be brought close to each other, the area where the ink stagnates in the pressure chamber C can be reduced. As a result, air bubbles in the pressure chamber C can be easily discharged to the circulating liquid chamber 65. Further, it is possible to make it difficult for air bubbles to enter the pressure chamber C from the first circulation passage 71 as compared with the case where the vertical DC passage extending from the lower side of the pressure chamber C is connected to the circulating liquid chamber 65.

For example, in the configuration of FIG. 6, as shown in the plan view of the same figure, the first circulation path 71 extends in the X direction, which is the direction in which the pressure chamber C extends from the pressure chamber C in a plan view. As a result, as shown in the cross-sectional view of FIG. 6, the first circulation path 71 extends in the same X direction as the direction of the ink flow in the pressure chamber C, so that the first circulation path 71 is shown as shown by the thick broken line arrow. The direction of the ink flow through the pressure chamber C can be the same as the direction of the ink flow in the pressure chamber C in the X direction. Therefore, the area where the ink stagnates in the pressure chamber C can be reduced as compared with the case where the ink is connected to the circulating liquid chamber 65 from below the pressure chamber C by a vertical DC path, so that the bubbles in the pressure chamber C circulate. It can be easily discharged to the liquid chamber 65.

As shown in FIGS. 2 and 6, in the first embodiment, the first circulation path 71 is connected to one of the two sides of the pressure chamber C in the X direction (the side closer to the virtual surface O). .. By connecting the first circulation passage 71 to the side surface of the pressure chamber C in this way, it is possible to easily match the direction of the ink flow through the first circulation passage 71 with the direction of the ink flow in the pressure chamber C. ..

Further, on each of the two side surfaces of the pressure chamber C in the X direction of the first embodiment, inclined surfaces inclined so that the height (dimension in the Z direction) of the pressure chamber C increases toward the inside of the pressure chamber C. Fc is formed. In the first embodiment, an inclined surface Fc is formed at a portion where each of the two side surfaces of the pressure chamber C in the X direction and the upper surface of the pressure chamber C (the surface on the positive side in the Z direction of the vibrating portion 42) intersect. Illustrate the case. That is, an inclined surface Fc is formed at a corner where the upper surface and the side surface of the pressure chamber C intersect. Each inclined surface Fc intersects the upper surface of the pressure chamber C and inclines inward of the pressure chamber C so as to diagonally face the lower surface of the pressure chamber C. The inclined surface Fc may be a flat surface or a curved surface.

As described above, by providing the inclined surface Fc at the corner portion of the internal space of the pressure chamber C where the ink tends to stagnate, the ink can easily flow. Further, by forming the inclined surface Fc on the side surface to which the first circulation path 71 is connected, it becomes easy to guide the bubbles that have entered the pressure chamber C to the first circulation path 71 along the inclined surface Fc. Therefore, the air bubbles that have entered the pressure chamber C are easily discharged from the first circulation passage 71. Further, since the first circulation passage 71 of the first embodiment is formed on the pressure chamber forming plate 34 of the flow path forming portion 30, the first circulation passage 71 is provided in the direction along the direction of the ink flow in the pressure chamber C. Easy to place.

In the first embodiment, among the inks that flow through the communication passage 63 by driving the piezoelectric element 44 once, the amount of ink discharged through the nozzle N is the first of the inks that flow through the communication passage 63. The inertia between the communication passage 63, the nozzle N, the first circulation passage 71, and the second circulation passage 72 is increased so as to exceed the circulation amount of the ink flowing into the circulation liquid chamber 65 through the circulation passage 71 and the second circulation passage 72. Be selected.

Specifically, for example, the communication passage 63 and the nozzle so that the circulation amount ratio of the ink flowing through the communication passage 63 from the pressure chamber C is 70% or more (the ejection amount ratio is 30% or less). The flow path resistances of N, the first circulation path 71, and the second circulation path 72 are determined. According to the above configuration, it is possible to effectively circulate the ink in the vicinity of the nozzle N to the circulating liquid chamber 65 while ensuring the ink ejection amount. The ratio of the ink ejection amount to the circulation amount described above is not limited to 70%, and can be adjusted by the flow path resistance of the first circulation path 71 and the second circulation path 72. As the flow path resistance of the first circulation path 71 and the second circulation path 72 is increased, the circulation amount can be reduced while the discharge amount can be increased, and the flow paths of the first circulation path 71 and the second circulation path 72 can be increased. The smaller the resistance, the more the circulation amount can be increased while the discharge amount can be decreased.

In the first embodiment, the flow path resistance of the second circulation path 72 is reduced to the first circulation path by making the flow path cross-sectional area or the flow path length different between the first circulation path 71 and the second circulation path 72. Although the case where the resistance is made smaller than the flow path resistance of 71 is illustrated, the present invention is not limited to this configuration. For example, as in the first modification shown in FIG. 7, the opening area A2 of the flow path port on the pressure chamber C side of the second circulation path 72 is larger than the opening area A1 of the flow path port on the communication passage 63 side of the first circulation path 71. May also be increased. Further, as in the second modification shown in FIG. 8, a throttle flow path 712 having a narrowed flow path cross-sectional area may be provided in a part of the first circulation path 71. Also by the configuration of FIG. 7 and the configuration of FIG. 8, the flow path resistance of the second circulation path 72 can be made smaller than the flow path resistance of the first circulation path 71.

Further, as shown in FIG. 2, the first circulation path 71 of the first embodiment overlaps with the second circulation path 72 (when viewed from the Z direction) in a plan view. The first circulation path 71 may be overlapped with the entire second circulation path 72, or may be partially overlapped with the second circulation path 72. In this way, when the first circulation path 71 is arranged so as to overlap the second circulation path 72 in a plan view, the first circulation path 71 and the second circulation path 72 are arranged so as not to overlap in a plan view. The liquid discharge head 26 can be miniaturized in the direction along the XY plane.

Further, bubbles can be discharged even if the liquid discharge head 26 is turned upside down so that the nozzle N is on the top. The case where the liquid discharge head 26 is turned upside down is not only when the liquid discharge head 26 is turned upside down with the liquid discharge device 100 removed, but also when the liquid discharge head 26 is attached with the liquid discharge head 26 turned upside down. included. In the present embodiment, the first circulation path 71 is arranged so as to overlap the second circulation path 72 in a plan view. Therefore, when the liquid discharge head 26 is turned upside down, the bubbles in the pressure chamber buoyantly enter the communication passage 63. Since it moves to the nozzle N side through it, it is discharged from the nozzle N. At this time, by turning the liquid discharge head 26 upside down, the first circulation path 71 and the second circulation path 72 are turned upside down. Therefore, since the first circulation passage 71 is located on the pressure chamber C side below the communication passage 63, foreign matter or thickened ink that has fallen from the inside of the communication passage 63 into the pressure chamber C can be removed from the first circulation passage 71 to the circulation liquid chamber 65. It becomes easy to be discharged. In particular, since the first circulation path 71 and the second circulation path 72 of the first embodiment are vertically parallel to each other and are arranged so as to extend in the horizontal direction, even if the liquid discharge head 26 is turned upside down. , The direction in which the first circulation path 71 and the second circulation path 72 extend does not change. Therefore, even if the liquid discharge head 26 is turned upside down, a horizontal flow can be generated in the first circulation path 71 and the second circulation path 72 as in the case where the liquid discharge head 26 is not inverted. Therefore, even if the liquid ejection head 26 is turned upside down, foreign matter and thickened ink can be easily discharged to the circulating liquid chamber 65.

<Second Embodiment>
A second embodiment of the present invention will be described. For the elements whose actions and functions are the same as those of the first embodiment in each of the embodiments exemplified below, the reference numerals used in the description of the first embodiment will be diverted and detailed description of each will be omitted as appropriate.

FIG. 9 is a cross-sectional view of the liquid discharge head 26 according to the second embodiment cut in a cross section perpendicular to the Y direction, and corresponds to FIG. 2. The flow path configuration is different between the liquid discharge head 26 of the second embodiment and the liquid discharge head 26 of the first embodiment. That is, in the first embodiment, a flow path configuration in which ink is introduced into the pressure chamber C by a supply path 61 extending in the Z direction from below the pressure chamber C is illustrated. In the second embodiment, a flow path configuration in which ink is introduced into the pressure chamber C by a supply path 61 extending in the X direction from the side of the pressure chamber C is illustrated.

The first portion P1 and the second portion P2 shown in FIG. 9 have a flow path configuration corresponding to one nozzle N. FIG. 9 shows that the configuration of the first portion P1 and the second portion P2 inverted on the positive side and the negative side in the X direction and the configuration of the first portion P1 and the second portion P2 similar to those in FIG. 9 are in the Y direction. Are arranged alternately in. It should be noted that a plurality of configurations of the first portion P1 and the second portion P2 similar to those in FIG. 9 may be arranged side by side in the Y direction.

The liquid storage chamber R of the first portion P1 shown in FIG. 9 is composed of the space Rb formed in the first portion P1 of the housing portion 48. The liquid storage chamber R of the second portion P2 is composed of the space Rb formed in the second portion P2 of the housing portion 48. The supply path 61 of the first portion P1 in FIG. 9 communicates the liquid storage chamber R with the side surface of the pressure chamber C on the positive side in the X direction. The second circulation path 72 of FIG. 9 penetrates the partition wall portion 69 from the communication passage 63 on the positive side in the X direction to the circulation liquid chamber 65 on the negative side in the X direction through the surface of the communication plate 32 facing the nozzle plate 52. Is formed. In the configuration of FIG. 9, the second circulation path 72 may be formed on the nozzle plate 52 in the same manner as in the configuration of FIG. The first circulation passage 71 shown in FIG. 9 is formed on the surface of the pressure chamber forming plate 34 facing the communication plate 32 in the same manner as in the configuration of FIG. 2, and communicates the pressure chamber C with the circulation liquid chamber 65. The pressure chamber C, the supply passage 61, the communication passage 63, and the nozzle N are not formed in the second portion P2 of FIG.

Also in the configuration of FIG. 9, the flow path resistance of the second circulation path 72 can be made smaller than the flow path resistance of the first circulation path 71. As a result, foreign matter and thickening ink due to sedimentation of ink that tends to accumulate in the vicinity of the nozzle N in the communication passage 63 are easily discharged from the second circulation passage 72 to the circulating liquid chamber 65, so that foreign matter and thickening ink can be efficiently discharged. It can be discharged.

<Third Embodiment>
A third embodiment of the present invention will be described. FIG. 10 is a cross-sectional view of the liquid discharge head 26 according to the third embodiment cut in a cross section perpendicular to the Y direction, and corresponds to FIG. 2. The liquid discharge head 26 of the third embodiment and the liquid discharge head 26 of the first embodiment have different wiring structures for supplying the drive signal of the piezoelectric element 44. That is, in the first embodiment, the case where the drive signal is supplied to the piezoelectric element 44 by the wiring board 28 is exemplified. In the third embodiment, a case where the drive IC 29 is mounted on the protective member 46 and the wiring between the drive IC 29 and the piezoelectric element 44 is provided on the protective member 46 is illustrated. The drive IC 29 is electrically connected to the control unit 20 by a flexible wiring board such as an FPC (Flexible Printed Circuit) or an FFC (Flexible Flat Cable).

The drive IC 29 is mounted on the surface (mounting surface) of the protective member 46 of FIG. 10 opposite to the vibrating portion 42 side. The drive IC 29 is a substantially rectangular IC chip that drives each piezoelectric element 44 by generating and supplying a drive signal of the piezoelectric element 44 under the control of the control unit 20. At least a part of the piezoelectric element 44 of the liquid discharge head 26 overlaps the drive IC 29 in a plan view. The protective member 46 of FIG. 10 is provided with a plurality of connection terminals 464 and a plurality of wirings 466 for electrically connecting the drive IC 29 and each piezoelectric element 44, and the protective member 46 of the third embodiment is provided. It also functions as a wiring board.

The plurality of wirings 466 are divided into wirings 466a and wirings 466b. The connection terminal 464 is divided into a connection terminal 464a electrically connected to the wiring 466a and a connection terminal 464b electrically connected to the wiring 466b. The wiring 466a is a wiring connected to the output terminal of the base voltage of the drive IC 29, and is continuously formed in the Y direction across the plurality of piezoelectric elements 44.

The connection terminal 464a connects the first electrode 441, which is a common electrode of each piezoelectric element 44, and the wiring 466a. As a result, the first electrode 441 of each piezoelectric element 44 is connected to the output terminal of the base voltage of the drive IC 29 via the connection terminal 464a and the wiring 466a. Therefore, the base voltage output from the output terminal of the drive IC 29 is applied to the first electrode 441 of each piezoelectric element 44 via the wiring 466a and the connection terminal 464a.

The connection terminal 464b connects the second electrode 442, which is an individual electrode of each piezoelectric element 44, and the wiring 466b. As a result, the second electrode 442 of each piezoelectric element 44 is connected to the output terminal of the drive signal of the drive IC 29 via the connection terminal 464b and the wiring 466b. Therefore, the drive signal output from the output terminal of the drive IC 29 is applied to the second electrode 442 of each piezoelectric element 44 via the connection terminal 464b and the wiring 466b.

As shown in FIG. 10, each of the connection terminals 464a and 464b is composed of, for example, resin core bumps in which protrusions formed of a resin material are coated with a conductive material. However, the connection terminals 464a and 464b are not limited to the resin core bumps, and may be formed of metal bumps. The connection terminal 464 of the present embodiment is arranged so as to overlap the first circulation path 71 or the circulation liquid chamber 65 in a plan view (when viewed from the Z direction). According to this, a current flows through the wiring 466 and the connection terminal 464 by driving the piezoelectric element 44, so that even if the wiring 466 and the connection terminal 464 generate heat, the heat from the wiring 466 and the connection terminal 464 is first circulated. It can be efficiently released to the circulating liquid chamber 65 on the flow of ink in the path 71.

Also in the configuration of FIG. 10, the flow path resistance of the second circulation path 72 can be made smaller than the flow path resistance of the first circulation path 71. As a result, foreign matter and thickening ink due to sedimentation of ink that tends to accumulate in the vicinity of the nozzle N in the communication passage 63 are easily discharged from the second circulation passage 72 to the circulating liquid chamber 65, so that foreign matter and thickening ink can be efficiently discharged. It can be discharged.

<Fourth Embodiment>
A fourth embodiment of the present invention will be described. FIG. 11 is a cross-sectional view of the liquid discharge head 26 according to the fourth embodiment cut in a cross section perpendicular to the Y direction, and corresponds to FIG. 2. The flow path configuration is different between the liquid discharge head 26 of the fourth embodiment and the liquid discharge head 26 of the first embodiment. That is, in the first embodiment, the case where one circulating liquid chamber 65 is provided is exemplified, but in the fourth embodiment, the case where a plurality of circulating liquid chambers are provided is exemplified.

FIG. 11 illustrates a case where one circulating liquid chamber 65a (first circulating liquid chamber) and two circulating liquid chambers 65b (second circulating liquid chamber) are formed in the communication plate 32. The circulating liquid chamber 65a is formed between the nozzle N of the first nozzle row L1 and the nozzle N of the second nozzle row L2 in the communication plate 32, and corresponds to the circulating liquid chamber 65 of FIG.

One of the two circulating liquid chambers 65b is formed between the nozzle N of the first nozzle row L1 and the supply path 61 on the first portion P1 side of the communication plate 32. The other circulating liquid chamber 65b is formed between the nozzle N of the second nozzle row L2 and the supply path 61 on the second portion P2 side of the communication plate 32. The circulating liquid chamber 65b is a long bottomed hole (groove portion) formed on the side opposite to the circulating liquid chamber 65 with the communication passage 63 and the nozzle N interposed therebetween and extending in the Y direction. The nozzle plate 52 joined to the surface Fb of the communication plate 32 closes the openings of the circulating liquid chamber 65a and the circulating liquid chamber 65b.

A plurality of first circulation paths 71 for communicating the pressure chamber C with the circulating liquid chamber 65a are formed on the surface of the pressure chamber forming plate 34 of FIG. 11 facing the communication plate 32. The plurality of first circulation passages 71 of the first portion P1 correspond one-to-one to the plurality of pressure chambers C of the first nozzle row L1. Further, the plurality of first circulation passages 71 of the second portion P2 correspond one-to-one to the plurality of pressure chambers C of the second nozzle row L2.

A plurality of second circulation paths 72a that communicate the communication passage 63 with the circulation liquid chamber 65a are formed on the surface of the nozzle plate 52 of FIG. 11 facing the flow path forming portion 30. A plurality of second circulation paths 72a are arranged for each of the first portion P1 and the second portion P2. The plurality of second circulation paths 72a of the first portion P1 correspond one-to-one to the plurality of communication passages 63 of the first nozzle row L1. Further, the plurality of second circulation paths 72a of the second portion P2 correspond one-to-one with the plurality of communication passages 63 of the second nozzle row L2.

Further, on the surface of the nozzle plate 52 of FIG. 11 facing the flow path forming portion 30, a plurality of second circulation paths 72b that communicate the communication passage 63 with the circulation liquid chamber 65b are formed. A plurality of second circulation paths 72b are arranged for each of the first portion P1 and the second portion P2. The plurality of second circulation paths 72b of the first portion P1 correspond one-to-one to the plurality of communication passages 63 of the first nozzle row L1. Further, the plurality of second circulation paths 72b of the second portion P2 correspond one-to-one to the plurality of communication passages 63 of the second nozzle row L2.

According to the fourth embodiment of the above configuration, the ink is circulated by the path flowing from the communication passage 63 to the circulation liquid chamber 65a via the second circulation passage 72a, and the ink is circulated from the communication passage 63 through the second circulation passage 72b. The ink is also circulated by the path flowing through the circulating liquid chamber 65b. Therefore, foreign matter and thickening ink due to sedimentation of ink that tends to accumulate in the vicinity of the nozzle N in the communication passage 63 can be discharged not only from the circulating liquid chamber 65a but also from the circulating liquid chamber 65b. Therefore, it is possible to improve the discharge property of foreign matter and thickening ink. In the fourth embodiment, the pressure chamber C is communicated with the circulation liquid chamber 65a in the first circulation passage 71, and the communication passage 63 is communicated with the circulation liquid chamber 65b in the second circulation passage 72b without providing the second circulation passage 72a. It is also possible to communicate with.

In the configuration of FIG. 11, the case where the second circulation paths 72a and 72b are formed on the nozzle plate 52 is illustrated, but the configuration is not limited to such a configuration. The second circulation passages 72a and 72b may be formed in the flow path forming portion 30. For example, in the third modification shown in FIG. 12, the case where the second circulation paths 72a and 72b are formed in the communication plate 32 is illustrated. Further, in the configuration of FIG. 11, the case where the second circulation path 72b is arranged along the X direction in the same manner as the second circulation path 72a is illustrated, but as in the third modification shown in FIG. 12, for example, the second circulation path 72b is illustrated. The two circulation paths 72b may be inclined so as to intersect in the X direction. The second circulation passage 72b in FIG. 12 is inclined so that the height in the vertical direction becomes higher toward the position closer to the circulation liquid chamber 65b from the communication passage 63. According to this configuration, not only the foreign matter and the thickening ink accumulated in the communication passage 63 but also the bubbles entering the communication passage 63 can be easily discharged from the second circulation passage 72b. It is also possible to configure the second circulation passage 72a in FIG. 12 to be inclined so that the height in the vertical direction becomes higher as the position closer to the circulation liquid chamber 65a from the communication passage 63.

<Modification example>
The embodiments and embodiments exemplified above can be variously modified. Specific modes of modification are illustrated below. Two or more embodiments arbitrarily selected from the following examples and the above embodiments may be appropriately merged to the extent that they do not contradict each other.

(1) In the above-described embodiment, a serial head in which a carriage 242 equipped with a liquid discharge head 26 is repeatedly reciprocated along the X direction is exemplified, but a line head in which the liquid discharge heads 26 are arranged over the entire width of the medium 12. The present invention can also be applied to the above.

(2) In the above-described embodiment, the piezoelectric liquid discharge head 26 having a piezoelectric element that applies mechanical vibration to the pressure chamber as a pressure generating portion is exemplified, but bubbles are generated inside the pressure chamber by heating. It is also possible to adopt a thermal type liquid discharge head using a heat generating element as a pressure generating part.

(3) The liquid discharge device 100 exemplified in the above-described embodiment can be adopted in various devices such as a facsimile machine and a copier, in addition to a device dedicated to printing. However, the application of the liquid ejection device 100 of the present invention is not limited to printing. For example, a liquid discharge device that discharges a solution of a coloring material is used as a manufacturing device for forming a color filter of a liquid crystal display device, an organic EL (field emission display), an FED (field emission display), and the like. Further, a liquid discharge device that discharges a solution of a conductive material is used as a manufacturing device for forming wiring and electrodes on a wiring substrate. It is also used as a chip manufacturing device that discharges a solution of a bio-organic substance as a kind of liquid.

100 ... liquid discharge device, 12 ... medium, 14 ... liquid container, 20 ... control unit, 22 ... transfer mechanism, 24 ... movement mechanism, 242 ... carriage, 244 ... transfer belt, 26 ... liquid discharge head, 28 ... wiring board, 29 ... drive IC, 30 ... flow path forming part, 32 ... communication plate, 34 ... pressure chamber forming plate, 42 ... vibrating part, 44 ... piezoelectric element, 441 ... first electrode, 442 ... second electrode, 443 ... piezoelectric body Layer, 46 ... protective member, 464 ... connection terminal, 464a ... connection terminal, 464b ... connection terminal, 466 ... wiring, 466a ... wiring, 466b ... wiring, 48 ... housing, 482 ... introduction port, 52 ... nozzle plate, 54 ... vibration absorber, 61 ... supply path, 63 ... communication passage, 65 ... circulating fluid chamber, 65a ... circulating fluid chamber, 65b ... circulating fluid chamber, 69 ... partition wall, 71 ... first circulation passage, 712 ... flow path, 72 ... second circulation path, 72a ... second circulation path, 72b ... second circulation path, 75 ... circulation mechanism, A1 ... opening area, A2 ... opening area, C ... pressure chamber, D1 ... flow path length, D2 ... Flow path length, Fa ... surface, Fb ... surface, Fc ... inclined surface, H1 ... flow path height, H2 ... flow path height, L1 ... first nozzle row, L2 ... second nozzle row, N ... nozzle, Nd ... Flow path length, Nw ... Inner diameter, O ... Virtual surface, P1 ... First part, P2 ... Second part, R ... Liquid storage chamber, Ra ... Space, Rb ... Space, W1 ... Flow path width, W2 ... Channel width.

Claims (10)

Nozzle plate with nozzle and
A pressure chamber to which a liquid is supplied, a communication passage connecting the pressure chamber to the nozzle, and a flow path forming portion provided with a circulating liquid chamber.
A pressure generating part that generates a pressure change in the pressure chamber,
A first circulation path that communicates the pressure chamber with the circulating liquid chamber and discharges the liquid from the pressure chamber .
A second circulation passage that communicates the communication passage with the circulation liquid chamber and discharges the liquid from the communication passage is provided.
The flow path resistance of the second circulation path is smaller than the flow path resistance of the first circulation path. The liquid discharge head according to claim 1, wherein the flow path resistance of the nozzle is smaller than the flow path resistance of the first circulation path and smaller than the flow path resistance of the second circulation path. The liquid discharge head according to claim 1 or 2, wherein the flow path cross-sectional area of the second circulation path is larger than the flow path cross-sectional area of the first circulation path. The liquid discharge head according to any one of claims 1 to 3, wherein the flow path length of the second circulation path is shorter than the flow path length of the first circulation path. The liquid discharge head according to any one of claims 1 to 4, wherein a plurality of second circulation paths are provided. The liquid discharge head according to any one of claims 1 to 5, wherein the second circulation passage is inclined so that the height in the vertical direction becomes higher as the position closer to the circulating liquid chamber from the communication passage. The circulating fluid chamber includes a first circulating fluid chamber and a second circulating fluid chamber.
The first circulation passage communicates the first circulation liquid chamber with the pressure chamber, and allows the first circulation liquid chamber to communicate with the pressure chamber.
The liquid discharge head according to any one of claims 1 to 6, wherein the second circulation path communicates the second circulation liquid chamber with the communication passage. The liquid ejection head according to any one of claims 1 to 7, wherein the liquid is a pigment ink. The liquid ejection head according to any one of claims 1 to 8, wherein the liquid is an ink containing a solvent having a higher volatility than water. A liquid discharge device including the liquid discharge head according to any one of claims 1 to 9.

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