WO2023233862A1 - Inkjet head - Google Patents

Abstract

This inkjet head comprises: a plurality of pressure chambers communicating with a nozzle for jetting an ink; a first common flow passage communicating with the plurality of pressure chambers; and a connection flow passage connected to the first common flow passage, wherein the connection flow passage has an air bubble storage part for storing air bubbles.

Description

inkjet head

The present disclosure relates to an inkjet head.

In recent years, methods of manufacturing devices using inkjet printing equipment have attracted attention. An inkjet printing device applies droplets to an object to be printed by ejecting droplets from the nozzles while controlling the positional relationship between a plurality of nozzles included in the inkjet and the object to be printed. This type of inkjet printing apparatus requires a drop-on-demand type inkjet head that can eject the required amount of droplets at the required timing onto the printing target with high precision.

In drop-on-demand type inkjet heads, a phenomenon called fluid crosstalk is likely to occur. Fluid crosstalk is a phenomenon in which pressure fluctuations affect adjacent nozzles through a flow path. As a countermeasure against fluid crosstalk, a structure in which a damper is provided in a flow path to make it difficult for pressure to be transmitted to adjacent nozzles is widely adopted. However, due to the increasing density of nozzles in inkjet heads, it has become difficult to ensure a sufficient surface area of the damper. Furthermore, as the desired printing accuracy has increased, it has become difficult to suppress the influence of fluid crosstalk to a negligible level. To address such problems, Patent Document 1 discloses a method of suppressing fluid crosstalk using bubbles. Specifically, Patent Document 1 discloses a method in which a storage section for storing air bubbles is provided at an end (stop area) of a common flow path on the discharge side, and this storage section is used as a damper.

Patent No. 5475389

An inkjet head according to an aspect of the present disclosure includes a plurality of pressure chambers communicating with a nozzle that discharges ink, a first common channel communicating with the plurality of pressure chambers, and a first common channel connected to the first common channel. and a connection flow path, the connection flow path having a bubble storage section for storing air bubbles.

An exploded perspective view showing the basic configuration of an inkjet head according to each embodiment Cross-sectional view in the XZ plane near the nozzle of the inkjet head according to each embodiment A plan view showing an overview of the upstream common flow path and the connection flow path according to the first embodiment FIG. 3A is a vertical cross-sectional view taken along the line III-III of FIG. 3A, showing an outline of the connecting channel. FIG. 3A is a longitudinal cross-sectional view taken along the line III-III in FIG. 3A, and is an explanatory diagram of the action of the connecting channel. A vertical cross-sectional view showing an overview of a portion including an upper downward step of the connection channel according to the first embodiment A vertical cross-sectional view showing an example of a plate-like member used for forming the upper downward step according to the first embodiment. A vertical cross-sectional view showing another example of the plate member used for forming the upper downward step according to the first embodiment. A vertical cross-sectional view showing a modification of the first embodiment A vertical cross-sectional view showing another modification of the first embodiment A vertical cross-sectional view showing still another modification of the first embodiment A plan view showing an outline of the upstream common flow path and the connection flow path according to the second embodiment FIG. 6A is a vertical cross-sectional view taken along line VI-VI in FIG. 6A, showing an outline of the connection channel. A plan view showing an overview of the upstream common flow path, the downstream common flow path, and the connection flow path according to the third embodiment FIG. 7A is a longitudinal cross-sectional view taken along the line VII-VII of FIG. 7A, showing an outline of the connecting channel. A plan view showing an overview of the upstream common flow path, the downstream common flow path, and the connection flow path according to the fourth embodiment FIG. 8A is a vertical cross-sectional view taken along the line VIII-VIII of FIG. 8A, showing an outline of the connecting channel. A plan view showing an outline of an inkjet head according to a modification of the fourth embodiment A plan view showing an outline of an inkjet head according to another modification of the fourth embodiment An explanatory diagram of a method for forming a connection flow path according to the fifth embodiment A cross-sectional view in the YZ plane near the upstream common flow path according to the seventh embodiment A cross-sectional view in the YZ plane near the downstream common flow path according to the seventh embodiment A plan view showing an outline of a connection flow path according to a modified example A vertical cross-sectional view showing an outline of a connection channel according to another modification

As described in Patent Document 1, in the method of storing air bubbles in a still area, the amount of air bubbles stored cannot be kept constant because the force that discharges air bubbles exceeding a certain amount by the flow of ink does not work. becomes difficult. If the amount of bubbles stored is not kept constant and varies over time, the effectiveness as a damper will vary, resulting in variations in discharge speed and volume, resulting in poor discharge accuracy.

In order to solve this problem, Patent Document 1 describes a method in which a bubble generating means for generating bubbles and a bubble detecting means for detecting bubbles in a flow path are provided, and the bubbles are generated according to the detected amount of bubbles. ing. However, in the configuration described in Patent Document 1, there is a trade-off between miniaturization and manufacturing cost, so there are high barriers to mounting the bubble generating means and the bubble detecting means. In addition, in the detection accuracy of commonly used bubble detection means or the accuracy of bubble generation control in bubble generation means, it is necessary to suppress variations in bubbles over time and to suppress variations in discharge speed and volume. becomes difficult.

An object of the present disclosure is to provide an inkjet head that can suppress variations in the state of ink ejection.

Hereinafter, an inkjet head in an embodiment of the present disclosure will be described with reference to the drawings. In the following explanation and each figure, the direction parallel to the direction of ink ejection from the inkjet head is the Z-axis direction, the direction in which the nozzles in the inkjet head are lined up is the Y-axis direction, and the direction perpendicular to the Z-axis direction and the Y-axis direction. is defined as the X-axis direction. Further, the ink ejection direction is defined as the −Z direction.

[Basic configuration of inkjet head]
First, the basic configuration of the inkjet head according to the embodiment will be described. FIG. 1 is an exploded perspective view showing the basic configuration of an inkjet head.

As shown in FIG. 1, the inkjet head 1 includes a housing section 10, a vibration plate 20, a channel plate 30, a nozzle plate 40, and a pressure variation section 50. The nozzle plate 40 and the flow path plate 30, the flow path plate 30 and the vibration plate 20, the vibration plate 20 and the housing part 10, and the vibration plate 20 and the pressure variation part 50 are each fixed via an adhesive. As the adhesive, for example, an epoxy adhesive having thermosetting properties can be used. Note that the same adhesive or different adhesives may be used for bonding the respective members. For example, a rubber adhesive may be used to bond certain members, and an epoxy adhesive may be used to bond other members.

The inkjet head 1 turns ink into droplets and discharges them from nozzles 41 formed in a nozzle plate 40. The nozzles 41 may be provided in one row in the Y-axis direction, or may be provided in multiple rows in the Y-axis direction as shown in FIG.

Next, the internal structure of the inkjet head will be explained. FIG. 2 is a cross-sectional view in the XZ plane near the nozzles of the inkjet head.

The nozzle plate 40 is arranged on the bottom surface of the channel plate 30 so that one surface in the thickness direction is perpendicular to the Z-axis. The nozzle plate 40 is formed, for example, by molding a stainless steel plate member with a thickness of 100 μm by etching or press working. The nozzle plate 40 has a plurality of nozzles 41 arranged in the Y-axis direction. The nozzle 41 discharges ink to the outside. Nozzle 41 is formed to penetrate nozzle plate 40. The diameter of the nozzle 41 is, for example, 3 μm or more and 100 μm or less.

The flow path plate 30 is formed in the shape of a rectangular parallelepiped, and is arranged between the vibration plate 20 and the nozzle plate 40 so that one surface in the thickness direction is perpendicular to the Z-axis. The flow path plate 30 is formed by laminating stainless steel plate-shaped members having a thickness of, for example, 10 μm or more and 100 μm or less, which are formed by, for example, etching or press processing. The number of layers of the stainless steel plate member is, for example, 3 or more and 10 or less.

The flow path plate 30 is formed with a plurality of pressure chambers 33 that communicate with the plurality of nozzles 41 on a one-to-one basis, and a silo portion 36 that communicates the pressure chambers 33 and the nozzles 41. The pressure chamber 33 is formed in the shape of a rectangular parallelepiped, and an upper wall forming an upper surface (+Z direction side surface) is constituted by the vibration plate 20. Note that the pressure chamber 33 is not a rectangular parallelepiped, and may have a plurality of steps formed on at least one surface that partitions the pressure chamber 33. The silo section 36 communicates the pressure chamber 33 and the nozzle 41 and stores ink. Note that the silo portion 36 may have a cylindrical shape or a quadrangular prism shape.

The channel plate 30 also includes a plurality of upstream individual channels 31, a first upstream common channel section 32, a plurality of downstream individual channels 34, and a first downstream common channel section 35. , is formed. The plurality of upstream individual flow paths 31 are arranged one-to-one for each pressure chamber 33 on the upstream side (+X direction side) of the ink flow direction (hereinafter sometimes referred to as "ink flow direction") with respect to each pressure chamber 33. It is communicated with. The first upstream common flow path portion 32 is communicated with the upstream end portions of the plurality of upstream individual flow paths 31 . The plurality of downstream individual channels 34 communicate with the pressure chambers 33 on a one-to-one basis on the downstream side (-X direction side) of each pressure chamber 33 in the ink flow direction. The first downstream common flow path section 35 communicates with the downstream ends of the plurality of downstream individual flow paths 34 .

The vibration plate 20 is arranged between the housing part 10 and the flow path plate 30 so that one surface in the thickness direction is perpendicular to the Z-axis. The vibrating plate 20 is a thin film having a thickness of, for example, 5 μm or more and 50 μm or less, and is made of, for example, polyimide.

The vibration plate 20 is formed with an upstream opening 21 located directly above the first upstream common flow path section 32 (on the +Z direction side). Further, the vibrating plate 20 is formed with a downstream opening 22 disposed directly above the first downstream common flow path section 35 . Instead of opening the entire surface of the upstream opening 21 and the downstream opening 22, the upstream opening 21 and the downstream opening 22 are configured with a plurality of through holes each having a diameter of 10 μm, for example, to provide a filter function. It's okay.

The housing portion 10 is formed into a rectangular parallelepiped shape with a thickness of 1 cm in the Z-axis direction, for example, by cutting alloy steel such as stainless steel. The housing part 10 includes a second upstream common channel section 12 disposed directly above the upstream opening 21 , a second downstream common channel section 14 disposed immediately above the downstream opening 22 , is formed. The second upstream common flow path section 12 constitutes an upstream common flow path 61 together with the first upstream common flow path section 32 and the upstream opening 21 . Further, the second downstream common flow path section 14 forms a downstream common flow path 62 together with the first downstream common flow path section 35 and the downstream opening 22 .

Further, the housing portion 10 is formed with an ink supply path (not shown) that supplies ink from the outside, and an ink discharge path (not shown) that discharges ink to the outside. The ink supply path is a flow path that supplies ink stored in a first ink tank (not shown) to the upstream common flow path 61. The ink supply path is formed in the housing portion 10, for example, along the Z-axis direction. The ink discharge path is a flow path for discharging ink from the downstream common flow path 62 to a second ink tank (not shown). The ink discharge path is formed in the housing portion 10, for example, along the Z-axis direction. The ink supplied from the ink supply path is discharged from the ink discharge path via the upstream common flow path 61, the upstream individual flow path 31, the pressure chamber 33, the downstream individual flow path 34, and the downstream common flow path 62. be done. That is, the ink flow direction in each of the individual channels 31 and 34 (the upstream individual channel 31 and the downstream individual channel 34) is set to the −X direction. Note that while the ink flow direction in a predetermined individual flow path 31, 34 is set in the +X direction, the ink flow direction in the remaining individual flow paths 31, 34 may be set in the -X direction.

Note that in order to circulate the ink, the first and second ink tanks are connected so that the pressure in the first ink tank connected to the ink supply path is higher than the pressure in the second ink tank connected to the ink discharge path. It is also possible to set the pressure of the tank and to flow ink from the second ink tank to the first ink tank using a pump (not shown). In order to make the pressure of the first ink tank higher than the pressure of the second ink tank, each ink tank may be arranged so that the height in the Z-axis direction with respect to the pressure chamber 33 is different, or each ink tank may be The internal pressure of each may be individually controlled by a regulator. Further, in order to circulate the ink, the ink may be circulated by the thrust of a pump. In this way, by circulating the ink in the pressure chamber 33 without allowing it to remain, the drying prevention function of the nozzle 41 can be activated. Therefore, it is possible to prevent ink from remaining in the pressure chamber 33 or the nozzle 41 and clogging the nozzle.

The pressure fluctuation section 50 is arranged inside the housing section 10 and generates pressure fluctuations in the ink within the pressure chamber 33. This pressure fluctuation propagates toward the nozzle 41, and ink is ejected from the nozzle 41. In addition, in order to receive the fluctuations of the pressure fluctuation part 50, the vibration plate 20 is formed with a plurality of convex parts 24 that protrude in the +Z direction and extend along the X-axis direction so as to be lined up in the Y-axis direction. . The pressure variation section 50 includes a base section 51, a piezoelectric element 52, a substrate 53, and a control section (not shown).

The base portion 51 is formed in a rectangular parallelepiped shape extending in the Y-axis direction, and holds the piezoelectric element 52 and the substrate 53. A plurality of piezoelectric elements 52 are arranged on the bottom surface side of the base portion 51. The plurality of piezoelectric elements 52 are arranged so as to be in contact with the convex portions 24 of the vibrating plate 20 that constitute the upper wall (+Z direction side wall) of the pressure chamber 33, respectively. The piezoelectric element 52 deforms to expand and contract along the Z-axis direction by applying a voltage. Specifically, the piezoelectric element 52 is a D33 mode stacked piezo actuator. The substrate 53 applies a voltage to the piezoelectric element 52. The board 53 is, for example, a flexible printed circuit board. The control unit controls application of voltage to the piezoelectric element 52.

The piezoelectric element 52 to which a voltage is applied by the substrate 53 is deformed so as to extend along the Z-axis direction, and pushes the convex portion 24 downward (in the -Z direction). As a result, the upper wall of the pressure chamber 33 (the wall on the +Z direction side) is deformed, and the pressure of the ink within the pressure chamber 33 changes. As this pressure fluctuation propagates toward the nozzle 41 via the silo section 36, ink is ejected from the nozzle 41 to the outside. In this manner, the control unit controls the ejection of ink by controlling the application of voltage to the piezoelectric element 52.

[First embodiment]
A first embodiment of the present disclosure will be described. In the first embodiment, in an inkjet head 1 of a type that does not circulate ink, the upstream side in the ink flow direction D (hereinafter, "upstream side in the ink flow direction D") is referred to as "upstream side" than the upstream common flow path 61. A configuration will be described in which fluid crosstalk is suppressed by storing air bubbles in (sometimes referred to as). The upstream common flow path 61 of the first embodiment corresponds to the first common flow path of the present disclosure. Note that in each of the following embodiments, the +Z direction side is defined as the upper side of the inkjet head 1. FIG. 3A is a plan view showing an outline of the upstream common channel and the connecting channel. FIG. 3B is a longitudinal cross-sectional view taken along line III-III in FIG. 3A, and shows an outline of the connection channel. FIG. 3C is a longitudinal cross-sectional view taken along line III-III in FIG. 3A, and is an explanatory diagram of the function of the connecting channel.

As shown in FIG. 3A, one end of the connection channel 7 is connected to the upstream end of the upstream common channel 61. The connection flow path 7 is formed to have a smaller cross-sectional area than the upstream common flow path 61. For example, an ink supply channel 11 is connected to the other end of the connection channel 7. In addition, when the connection flow path 7 is formed inside the flow path plate 30, it is not represented by a solid line in the plan view, but in order to show the concept, it is shown by a hatching pattern shown in FIG. 3A, and in the subsequent figures. A similar hatching pattern may also be used to illustrate the connection channel.

As shown in FIG. 3B, the connection channel 7 is configured to include at least one step. That is, the upper wall surface 71 constituting the upper side of the connecting channel 7 has two upper downward steps 72 formed so that the height becomes gradually lower as it goes downstream, and the upper wall surface 71 that is formed so that the height becomes gradually higher. It is configured to include two upper upward steps 73 formed so as to be. In addition, the lower wall surface 74 constituting the lower side of the connecting channel 7 has two lower downward steps 75 formed so that the height decreases in stages as it goes downstream. It is configured to include two lower upward steps 76 formed such that the height is higher than the lower side. Note that at least one of the upper downward step 72, the upper upward step 73, the lower downward step 75, and the lower upward step 76 may be provided.

The upper downward step 72 connects a pair of first upper wall surface parts 721 that guide ink in the -Y direction (first direction) and the pair of first upper wall surface parts 721, and guides ink in the -Z direction (second direction). ), and a second upper wall surface portion 722 that guides ink. The upper ascending step 73 includes a pair of first upper wall portions 731, a second upper wall portion 732 that connects the pair of first upper wall portions 731, and guides ink in the +Z direction (second direction); It is made up of. The lower downward step 75 includes a pair of first lower wall sections 751 that guide ink in the -Y direction, and a second lower wall section that connects the pair of first lower wall sections 751 and guides ink in the -Z direction. A wall portion 752. The lower ascending step 76 is composed of a pair of first lower wall surfaces 761 and a second lower wall surface section 762 that connects the pair of first lower wall surfaces 761 and guides ink in the +Z direction. There is. The first upper wall surface parts 721, 731 and the first lower wall surface parts 751, 761 correspond to the first part of the present disclosure, and the second upper wall surface parts 722, 732 and the second lower wall surface parts 752, 762 correspond to the first part of the present disclosure. This falls under Part 2 of

The first upper wall surface portion 721 and the second upper wall surface portion 722 on the upstream side forming the upper downward step 72 are connected to form a recessed corner portion 723. The second upper wall surface portion 732 constituting the upper ascending step 73 and the first upper wall surface portion 731 on the downstream side are connected to form a recessed corner portion 733. The second lower wall surface portion 752 constituting the lower downward step 75 and the first lower wall surface portion 751 on the downstream side are connected to form a recessed corner portion 753. The first lower wall surface portion 761 and the second lower wall surface portion 762 on the upstream side forming the lower ascending step 76 are connected to form a recessed corner portion 763 . It is preferable that the angle formed by each wall surface portion 721, 731, 751, 761 constituting each corner portion 723, 733, 753, 763 and each wall surface portion 722, 732, 752, 762 is 90° or less.

Note that the maximum width (length in the X-axis direction in FIG. 3A) of the upstream common flow path 61 is approximately 1 mm or more and 10 mm or less, and the height is approximately 0.3 mm or more and 3.0 mm or less, and the width of the connecting flow path 7 is approximately It is preferable that the length in the ink flow direction D is 1 mm or more and 10 mm or less, and the height of each step 72, 73, 75, 76 is about 10 μm or more and 200 μm or less. Further, the lengths of the upstream common flow path 61 and the connection flow path 7 in the ink flow direction D may be determined depending on the flow path configuration of the inkjet head 1.

Next, the functions and effects of forming the respective steps 72, 73, 75, and 76 in the connection channel 7 will be explained using FIG. 3C.

First, the flow rate of ink flowing through the connecting channel 7, the ink supply channel 11, and the upstream common channel 61 is significantly lower than in the case where the connecting channel 7 is not provided due to the channel resistance of the connecting channel 7. . Further, at each corner 723, 733, 753, 763 of each step 72, 73, 75, 76, the ink flow is locally weakened. Therefore, the main flow lines of the ink in the connection channel 7 flow to avoid the corners 723, 733, 753, and 763, as shown by the arrow D1 in FIG. 3C.

At each corner 723, 733, the upper wall surface 71 regulates the buoyant force acting on the bubbles B introduced into the connecting channel 7, and the force to push out the bubbles B due to the flow of ink is weak. A certain amount of bubbles B stays at each corner 723, 733. Further, at each corner 753, 763, the buoyant force acting on the bubble B is regulated by the flow of ink, so that a certain amount of the bubble B remains at each corner 753, 763. Therefore, the bubbles B are stored in a predetermined area near each corner 723, 733, 753, 763 of the connecting flow path 7. Each of the steps 72, 73, 75, and 76 corresponds to the bubble storage section of the present disclosure.

Note that the method for introducing the bubbles B into the connection channel 7 may be to introduce ink containing the bubbles B from the ink supply channel 11, or by sucking the bubbles B from the nozzle 41 and introducing them into the connection channel 7. Also good.

Furthermore, the size of the bubbles B introduced into the connection channel 7 may be the size that is stored in each corner 723, 733, 753, 763, or may be larger than the size that is stored. Even if bubbles B larger than the size to be stored in each corner 723, 733, 753, 763 are introduced, the bubbles B are divided into small pieces in the process of passing through the connecting channel 7 having a small cross-sectional area. , 733, 753, and 763.

Further, the amount of bubbles B introduced need not be strictly controlled as long as it is equal to or greater than the amount that causes bubbles B to be stored in each corner 723, 733, 753, 763. The air bubbles B that are not stored in the corners 723, 733, 753, 763 are washed away by the ink flow and are transferred to the first ink tank connected to the ink supply path or the second ink tank connected to the ink discharge path. This is because the ink is collected in an ink tank or the like. Therefore, bubbles B having a size equal to or less than the height of each of the steps 72, 73, 75, and 76 can be stored in the connecting channel 7 without using precise bubble detection.

According to the first embodiment, the amount of bubbles B stored in each corner 723, 733, 753, 763 varies depending on processing variations of each corner 723, 733, 753, 763, ink viscosity, etc. Unlike when stored in still water, changes over time are less likely to occur. The reason why the amount of bubbles B stored is difficult to change over time is that the amount of bubbles B that exceeds the amount that can be stored in each corner 723, 733, 753, 763 is washed away by the flow of ink. This is because the amount of bubbles B stored in 733, 753, and 763 is kept constant. Although the volume of air bubbles B stored in each corner 723, 733, 753, 763 is small compared to the volume of the upstream common flow path 61, since the elasticity of air is greater than that of ink, each corner 723 , 733, 753, and 763, even if the amount of bubbles B is minute, the effect of suppressing fluid crosstalk is large. Therefore, it is possible to store the air bubbles B in the connection flow path 7 to suppress the influence of fluid crosstalk, and to reduce variations in the amount of the stored air bubbles B over time, so that the ink ejection state (ejection speed and Variations in at least one of the discharge amounts can be suppressed.

In addition, when the upstream common channel 61 and the ink supply channel 11 are directly connected without the connection channel 7, air bubbles can be removed on the upstream side of the upstream common channel 61 (on the ink supply channel 11 side). There is no place to store it. For this reason, fluid crosstalk cannot be suppressed by utilizing the damper effect of air bubbles. In addition, the downstream side of the upstream common flow path 61 (opposite side of the ink supply path 11) serves as a water stop area, so air bubbles tend to accumulate there. Variation occurs in the fluid crosstalk suppression effect between the arranged nozzles 41 and the nozzles 41 arranged on the downstream side. On the other hand, in the first embodiment, since the connection channel 7 that can store the bubbles B is also present on the upstream side of the upstream common channel 61, the upstream and downstream sides of the upstream common channel 61 are Air bubbles B can be present on the side. Therefore, due to the fluid crosstalk suppressing effect using the damper effect of the bubbles B, variations in the ink ejection state between the nozzles 41 can be suppressed.

Next, an example of a method for forming the connection channel 7 will be described. FIG. 4A is a vertical cross-sectional view schematically showing a portion including an upper downward step of the connecting channel. FIG. 4B is a longitudinal cross-sectional view showing an example of a plate-like member used to form the upper downward step. FIG. 4C is a longitudinal cross-sectional view showing another example of a plate-like member used to form the upper downward step. Note that although a method for forming a portion of the connecting channel including the upper downward step 72 will be exemplified below, the upper upward step 73, the lower downward step 75, and the lower upward step 76 can also be formed in the same manner.

As shown in FIG. 4A, the upper downward step 72 includes a pair of first upper wall portions 721 and a second upper wall portion 722 that connects the pair of first upper wall portions 721. . The angle of the corner 723 formed by the first upper wall surface section 721 and the second upper wall surface section 722 on the upstream side is set to 90 degrees or less. The angle of the corner 723 is more preferably less than 90° in order to enhance the effect of storing the bubbles B.

In order to form the connection flow path 7 including the upper downward step 72 having such a shape, a method of overlapping thin film members (plate-like members) 70 having flow path through holes 701 as shown in FIG. 4B may be used. is desirable. This is because the method of forming the upper downward step 72 by machining one member tends to cause variations in machining accuracy and increases the machining cost.

When forming the connection channel 7 by overlapping the thin film members 70, by paying attention to the method of forming the channel through hole 701, it is possible to form the upper downward step 72 having a corner 723 of less than 90°. . For example, when forming the channel through hole 701 using a photo-etching method (single-sided etching method), as shown by arrow E1, by spraying an etching solution from the upper surface 702 side of the thin film member 70, the upper surface 702 A channel through hole 701 that becomes narrower toward the lower surface 703 can be formed. In other words, the flow path through hole 701 can be formed such that the angle between the upper surface of the flow path through hole 701 and the inner peripheral surface is less than 90° when viewed in longitudinal section. By overlapping such thin film members 70 such that the passage through holes 701 are shifted in the width direction, the upper downward step 72 having the corner portion 723 of less than 90° can be formed. Note that, as shown in FIG. 4C, if a double-sided etching method is used in which the thin film member 70 is etched from both sides as indicated by arrows E1 and E2, the upper surface and inner circumferential surface of the flow path through hole 701 are etched. The flow path through hole 701 can be formed such that the angle formed by the flow path through hole 701 and the angle formed between the lower surface and the inner circumferential surface of the flow path through hole 701 are each less than 90°. By overlapping such thin film members 70 such that the passage through holes 701 are shifted in the width direction, the upper downward step 72 having the corner portion 723 of less than 90° can be formed.

Note that the height of the second upper wall surface portion 722 is preferably 10 μm or more and 200 μm or less. When the height of the second upper wall surface portion 722 exceeds 200 μm, the flow amount of ink increases, so that the bubbles B may not be stored in the corner portion 723 . On the other hand, if the height of the second upper wall surface portion 722 is less than 10 μm, it becomes difficult to secure a space for storing the bubbles B.

Furthermore, it is preferable that the height of the second upper wall surface portion 722 is the same as the height of each individual flow path 31, 34. When the height of each individual flow path 31, 34 is not constant, it is preferable that the height of the second upper wall surface portion 722 is the same height as the lowest portion of each individual flow path 31, 34. In order to make the flow path resistance of the connection flow path 7 equal to the flow path resistance of each individual flow path 31 and 34 of each nozzle 41, the connection flow path 7 is made using the thin film member 70 that constitutes the flow path plate 30. This is because it is preferable to configure.

Furthermore, it is preferable that a plurality of each of the steps 72, 73, 75, and 76 exist in the connection channel 7. This is because a higher damping effect can be obtained by increasing the amount of bubbles B stored in each corner 723, 733, 753, 763. For example, as shown in FIG. 5A showing a modification of the connection channel 7, steps 72, 73, 75, and 76 may be formed so as to increase the number of consecutively descending steps or the number of ascending steps. As shown in FIG. 5B showing another modification of the flow path 7, the steps 72, 73, 75, and 76 may be formed so as to repeat going up and down. Furthermore, as shown in FIG. 5C showing still another modification of the connection channel 7, all the parts in the connection channel 7 that allow ink to flow in the horizontal direction (XY plane direction) have the same length. The steps 72, 73, 75, and 76 may be formed to prevent this from occurring. The shapes of other parts of the connection flow path 7 may be freely determined depending on dimensional constraints and the like.

Further, the connection flow path 7 may be formed to extend straight in the Y-axis direction, for example, or may be formed to include both a portion that moves straight in the Y-axis direction and a portion that moves straight in the X-axis direction.

[Second embodiment]
Next, a second embodiment of the present disclosure will be described. In the second embodiment, in an inkjet head of a type that circulates ink flowing through the upstream common flow path 61 but does not circulate ink flowing through the individual flow paths 31 and 34, the side upstream of the upstream common flow path 61 is A configuration will be described in which fluid crosstalk is suppressed by storing air bubbles on the downstream side. The upstream common flow path 61 of the second embodiment corresponds to the first common flow path of the present disclosure. FIG. 6A is a plan view showing an overview of the upstream common flow path and the connection flow path. FIG. 6B is a longitudinal cross-sectional view taken along line VI-VI in FIG. 6A, and shows an outline of the connection channel. Note that the same components as in the first embodiment are given the same names and symbols, and the explanation may be simplified or omitted.

As shown in FIG. 6A, one end of a connecting channel 7A having a smaller cross-sectional area than the upstream common channel 61 is connected to the upstream end of the upstream common channel 61. An ink supply path 11 is connected to the other end of the connection flow path 7A. One end of a connecting channel 7B having a smaller cross-sectional area than the upstream common channel 61 is connected to the downstream end of the upstream common channel 61. An ink discharge path 13 is connected to the other end of the connection flow path 7B. With such a configuration, the ink flowing through the upstream common flow path 61 is transferred to the upstream side via the ink discharge path 13, the second ink tank, the pump, the first ink tank, and the ink supply path 11 (not shown). It is returned to the side common flow path 61.

As shown in FIG. 6B, each of the connecting channels 7A and 7B is configured to include at least one step. That is, the upper wall surfaces 71A and 71B forming the upper side of each of the connection channels 7A and 7B are configured to include two upper downward steps 72 and two upper upward steps 73, respectively. . Further, the lower wall surfaces 74A and 74B forming the lower side of the connecting channel 7A are each configured to include two lower downward steps 75 and two lower upward steps 76 each. .

With the above configuration, when ink flows through the connection flow path 7A, the upstream common flow path 61, and the connection flow path 7B, air bubbles flow through the corners 723, 733, 753, and It is stored in a predetermined range of area near 763.

If the upstream common flow path 61 is not connected to both ends of the connection flow path 7A and the connection flow path 7B and the upstream common flow path 61 is directly connected to the ink supply path 11 and the ink discharge path 13, the upstream In the side common flow path 61, there is no place where air bubbles can be stored. For this reason, fluid crosstalk cannot be suppressed by utilizing the damper effect of air bubbles. On the other hand, in the second embodiment, by connecting the connection flow path 7A and the connection flow path 7B to both ends of the upstream common flow path 61, a fluid cross is formed near both ends of the upstream common flow path 61. Bubbles can be placed to suppress talk. Therefore, the influence of fluid crosstalk can be made uniform between the plurality of nozzles 41 arranged along the Y-axis direction.

Furthermore, by connecting the connection flow path 7A and the connection flow path 7B to both ends of the upstream common flow path 61, it is possible to prevent air bubbles from being stored in the upstream common flow path 61. Therefore, the air bubbles are stored upstream of the upstream common flow path 61, and it is possible to suppress variations in the ink ejection state caused by fluctuations in the amount of the stored air bubbles over time.

[Third embodiment]
Next, a third embodiment of the present disclosure will be described. In the third embodiment, in an inkjet head of a type that circulates ink flowing through each common channel 61, 62 and each individual channel 31, 34, air bubbles are stored upstream of each common channel 61, 62. Now, a configuration for suppressing fluid crosstalk will be explained. The upstream common flow path 61 of the third embodiment corresponds to the first common flow path of the present disclosure, and the downstream common flow path 62 corresponds to the second common flow path of the present disclosure. FIG. 7A is a plan view showing an overview of the upstream common flow path, the downstream common flow path, and the connection flow path. FIG. 7B is a longitudinal cross-sectional view taken along line VII-VII in FIG. 7A, and shows an outline of the connection channel. Note that the same components as in the first embodiment are given the same names and symbols, and the explanation may be simplified or omitted.

As shown in FIG. 7A, one end of a connecting channel 7C having a smaller cross-sectional area than the upstream common channel 61 is connected to the upstream end of the upstream common channel 61. The upstream end of the downstream common flow path 62 is connected to the other end of the connection flow path 7C. The ink supply path 11 is connected to the upstream side of the upstream common flow path 61 . The ink discharge path 13 is connected to the downstream side of the downstream common flow path 62 . With this configuration, a portion of the ink that has flowed through the upstream common flow path 61 flows into the ink discharge path 13 via each of the individual flow paths 31 and 34 and the downstream common flow path 62. Further, the remainder of the ink supplied from the ink supply path 11 flows into the ink discharge path 13 via the connection flow path 7C and the downstream common flow path 62. The ink that has flowed into the ink discharge path 13 is returned to the upstream common flow path 61 via a second ink tank, a pump, a first ink tank, and the ink supply path 11 (not shown), respectively.

As shown in FIG. 7B, the connection channel 7C is configured to include at least one step. That is, the upper wall surface 71C constituting the upper side of the connection channel 7C is configured to include three upper downward steps 72 and three upper upward steps 73. Further, the lower wall surface 74C forming the lower side of the connection flow path 7C is configured to include three lower downward steps 75 and three lower upward steps 76.

With the above configuration, when ink flows through the connection channel 7C, air bubbles are stored in a predetermined area near each corner 723, 733, 753, 763 of each step 72, 73, 75, 76.

If the connecting flow path 7C is not connected to the upstream end of the downstream common flow path 62, the upstream side of the downstream common flow path 62 becomes a water stop area, and the amount of bubbles accumulated there cannot be controlled. For this reason, the fluid crosstalk suppressing effect using the damper effect of air bubbles changes over time, and although the fluid crosstalk suppressing effect can be obtained, it is not possible to improve the reproducibility of ink landing. On the other hand, in the present third embodiment, by connecting the connection flow path 7C to the upstream end of the downstream common flow path 62, the water stop area can be eliminated from the upstream end of the downstream common flow path 62. At the same time, a certain amount of air bubbles can be stored in the connecting channel 7C. Therefore, it is possible to obtain a fluid crosstalk suppressing effect using the damper effect of air bubbles. Further, it is possible to suppress a change over time in the fluid crosstalk suppressing effect, and it is possible to improve the reproducibility of ink landing.

In addition, by connecting the upstream end portions of the upstream common flow path 61 and the downstream common flow path 62 via one connection flow path 7C, the upstream end portions of the upstream common flow path 61 and the downstream common flow path 62 are Air bubbles can be placed near the side edges to suppress fluid crosstalk. Therefore, there is no need to connect separate connection channels to the upstream sides of the upstream common channel 61 and the downstream common channel 62, and processing costs or channel formation space can be reduced. That is, even under the constraints of miniaturization and cost reduction, fluid crosstalk can be suppressed by storing air bubbles near the ends of each common flow path 61, 62.

In addition, by connecting the upstream common flow path 61 and the downstream common flow path 62 via one connection flow path 7C, damper components due to air bubbles in each of the upstream common flow path 61 and the downstream common flow path 62 can be The effects of can be made equal. Therefore, when ink is ejected, characteristics such as flow path resistance on the upstream side and the downstream side can be made constant, and ink ejection performance can be improved.

[Fourth embodiment]
Next, a fourth embodiment of the present disclosure will be described. In the fourth embodiment, in an inkjet head of a type that circulates ink flowing through each common channel 61, 62 and each individual channel 31, 34, air bubbles are removed on the upstream and downstream sides of each common channel 61, 62. A configuration for suppressing fluid crosstalk by storing fluid will be described. The upstream common flow path 61 of the fourth embodiment corresponds to the first common flow path of the present disclosure, and the downstream common flow path 62 corresponds to the second common flow path of the present disclosure. FIG. 8A is a plan view showing an outline of the upstream common flow path, the downstream common flow path, and the connection flow path. FIG. 8B is a longitudinal cross-sectional view taken along the line VIII-VIII of FIG. 8A, and shows an outline of the connection channel. Note that the difference between the fourth embodiment and the third embodiment is that the connection flow path 7D is provided, so the description will focus on this difference. Further, the same configurations as those in the first embodiment are given the same names and symbols, and the explanation may be simplified or omitted.

As shown in FIG. 8A, one end of a connecting channel 7D having a smaller cross-sectional area than the upstream common channel 61 is connected to the downstream end of the upstream common channel 61. The downstream end of the downstream common flow path 62 is connected to the other end of the connection flow path 7D. With such a configuration, a part of the ink that has flowed through the upstream common channel 61 is transferred to the ink via the individual channels 31 and 34 and the downstream common channel 62, or via the connecting channel 7D. It flows into the discharge path 13. Further, the remainder of the ink supplied from the ink supply path 11 flows into the ink discharge path 13 via the connection flow path 7C and the downstream common flow path 62. The ink that has flowed into the ink discharge path 13 is returned to the upstream common flow path 61 via a second ink tank, a pump, a first ink tank, and the ink supply path 11 (not shown), respectively.

As shown in FIG. 8B, the connection channel 7D is configured to include at least one step. That is, the upper wall surface 71D of the connection channel 7D is configured to include three upper downward steps 72 and three upper upward steps 73. Further, the lower wall surface 74D forming the lower side of the connection channel 7D is configured to include three lower downward steps 75 and three lower upward steps 76.

With the above configuration, when ink flows through the connection channels 7C and 7D, air bubbles are stored in a predetermined area near each corner 723, 733, 753, 763 of each step 72, 73, 75, 76. Ru.

When the connecting flow path 7C is not connected to the upstream end of the downstream common flow path 62, as explained in the third embodiment, the fluid crosstalk suppression effect using the damper effect of air bubbles changes over time. However, although the effect of suppressing fluid crosstalk can be obtained, the reproducibility of ink landing accuracy cannot be obtained. Furthermore, if the connecting flow path 7D is not connected to the downstream end of the upstream common flow path 61, the downstream side of the upstream common flow path 61 becomes a water stop area, and the amount of bubbles accumulated there cannot be controlled. . For this reason, the fluid crosstalk suppressing effect using the damper effect of air bubbles changes over time, and although the fluid crosstalk suppressing effect can be obtained, it is not possible to improve the reproducibility of ink landing. In contrast, in the fourth embodiment, the connection flow path 7C is connected to the upstream end of the downstream common flow path 62, and the connection flow path 7D is connected to the downstream end of the upstream common flow path 61. By doing so, it is possible to eliminate the cut-off area from the upstream end of the downstream common flow path 62 and the downstream end of the upstream common flow path 61, and at the same time, it is possible to eliminate a certain amount of air bubbles in each of the connecting flow paths 7C and 7D. can be accumulated. Therefore, it is possible to obtain a fluid crosstalk suppressing effect using the damper effect of air bubbles. Further, it is possible to suppress a change over time in the fluid crosstalk suppressing effect, and it is possible to improve the reproducibility of ink landing.

In addition, the number of the steps 72, 73, 75, 76 of the connection channel 7D is the same as the number of steps 72, 73, 75, 76 of the connection channel 7C, so that the upstream common channel 61 and the downstream common channel By providing the same amount of air bubbles on the upstream and downstream sides of each of the channels 62, variations in the ink ejection state between the nozzles 41 can be suppressed by the fluid crosstalk suppressing effect using the damper effect of the air bubbles. I can do it.

Moreover, by connecting the upstream ends of the upstream common flow path 61 and the downstream common flow path 62 with each other through the connection flow path 7C, and by connecting the downstream ends with each other through the connection flow path 7D, the upstream side common flow path 61 and the downstream common flow path 62 are connected with each other through the connection flow path 7D. Bubbles that suppress fluid crosstalk can be arranged near both ends of the flow path 61 and the downstream common flow path 62. Therefore, there is no need to connect separate connection channels to the upstream and downstream ends of the upstream common channel 61 and the downstream common channel 62, reducing processing costs or channel formation space. can do. That is, even under the constraints of miniaturization and cost reduction, fluid crosstalk can be suppressed by storing air bubbles near the ends of each common flow path 61, 62.

In addition, by connecting the upstream common flow path 61 and the downstream common flow path 62 via the connection flow paths 7C and 7D, damper components due to air bubbles in each of the upstream common flow path 61 and the downstream common flow path 62 can be The effects of can be made equal. Therefore, when ink is ejected, characteristics such as flow path resistance on the upstream side and the downstream side can be made constant, and ink ejection performance can be improved.

Furthermore, bubbles can be placed near both ends of the upstream common flow path 61 and the downstream common flow path 62 to suppress fluid crosstalk. Therefore, the influence of fluid crosstalk can be made uniform between the plurality of nozzles 41 arranged along the Y-axis direction.

In addition, by connecting the connection flow path 7C and the connection flow path 7D to both ends of the upstream common flow path 61 and the downstream common flow path 62, the inside of the upstream common flow path 61 and the downstream common flow path 62 can be It is possible to prevent air bubbles from being accumulated in the air. For this reason, air bubbles are stored at the respective ends of the upstream common flow path 61 and the downstream common flow path 62, and variations in the ink ejection state occur due to changes in the amount of stored air bubbles over time. can be suppressed.

Note that in order to reduce the size of the inkjet head, the upstream common channel 61 or the downstream common channel 62 may be used in common for a plurality of nozzle rows. FIG. 9A is a plan view showing an outline of an inkjet head according to a modification of the fourth embodiment. FIG. 9B is a plan view schematically showing an inkjet head according to another modification of the fourth embodiment.

As shown in FIG. 9A, the upstream common flow path 61 is formed to extend in the Y-axis direction in plan view. The downstream common flow path 62 includes a first portion 62A formed to extend in the Y-axis direction on the +X direction side of the upstream common flow path 61 and a −X direction side of the upstream common flow path 61 in a plan view. The second portion 62B is formed to extend in the Y-axis direction, and the third portion 62C connects the ends of the first portion 62A and the second portion 62B on the -Y direction side. The ink supply path 11 is connected to the +Y direction end of the upstream common flow path 61 . The ink discharge path 13 is connected to the longitudinal center of the third portion 62C of the downstream common flow path 62. The first portions 62A of the upstream common flow path 61 and the downstream common flow path 62 are connected via a plurality of upstream individual flow paths 31, pressure chambers 33, and downstream individual flow paths 34, respectively. The upstream common channel 61 and the second portion 62B of the downstream common channel 62 are connected via a plurality of upstream individual channels 31, pressure chambers 33, and downstream individual channels 34, respectively.

Moreover, one end of the connection flow path 7E and one end of the connection flow path 7F are connected to the +Y direction side end of the upstream common flow path 61. The other end of the connection flow path 7E is connected to the +Y direction side end of the first portion 62A of the downstream common flow path 62. The other end of the connection flow path 7F is connected to the +Y direction side end of the second portion 62B of the downstream common flow path 62. One end of the connection flow path 7G is connected to the -Y direction side end of the upstream common flow path 61. The other end of the connection flow path 7G is connected to the third portion 62C of the downstream common flow path 62 near the connection portion with the ink discharge path 13. Each of the connecting channels 7E, 7F, and 7G is formed such that its cross-sectional area is smaller than the cross-sectional area of the upstream common channel 61.

With the above configuration, a part of the ink supplied from the ink supply path 11 flows in the -Y direction through the upstream common flow path 61, and flows through the upstream individual flow path 31, the pressure chamber 33, and the downstream individual flow path. 34 to the first section 62A or second section 62B of the downstream common channel 62, or to the ink discharge channel 13 via the connecting channel 7G and the third section 62C. Further, the remaining ink supplied from the ink supply path 11 is passed through the connection channel 7E, the first section 62A, and the third section 62C, or through the connection channel 7F, the second section 62B, and the third section 62C. The ink flows into the ink discharge path 13 via the ink discharge path 13 . The ink that has flowed into the ink discharge path 13 is returned to the upstream common flow path 61 via a second ink tank, a pump, a first ink tank, and the ink supply path 11 (not shown), respectively.

Each of the connection channels 7E, 7F, and 7G is configured to include at least one step. That is, each of the connection channels 7E, 7F, and 7G includes an upper downward step 72, an upper upward step 73, a lower downward step 75, and a lower upward step 76, although not shown in FIG. 9A. It is configured.

With the above configuration, when ink flows through each of the connecting flow paths 7E, 7F, and 7G, air bubbles flow into a predetermined area near each corner 723, 733, 753, and 763 of each step 72, 73, 75, and 76. is stored in In other words, each level difference in each of the connection channels 7E, 7F, and 7G corresponds to the bubble storage section of the present disclosure.

In order to lengthen the connection flow path and arrange many steps, the inkjet head may be configured as shown in FIG. 9B. The inkjet head includes an upstream common channel 61, a first downstream common channel 62D, and a second downstream common channel 62E. The upstream common flow path 61, the first downstream common flow path 62D, and the second downstream common flow path 62E are formed to extend in the Y-axis direction in plan view. The upstream common flow path 61 and the first downstream common flow path 62D are connected via a plurality of upstream individual flow paths 31, pressure chambers 33, and downstream individual flow paths 34, respectively. The upstream common flow path 61 and the second downstream common flow path 62E are connected via a plurality of upstream individual flow paths 31, pressure chambers 33, and downstream individual flow paths 34, respectively.

Furthermore, one end of the connection flow path 7H is connected to the +Y direction side end of the upstream common flow path 61. The ink supply path 11 is connected to the other end of the connection flow path 7H. The ink supply path 11 is connected to one end of the connection channel 7I and one end of the connection channel 7J. The other end of the connection channel 7I is connected to the +Y direction side end of the first downstream common channel 62D. The other end of the connection channel 7J is connected to the +Y direction side end of the second downstream common channel 62E. One end of the connection flow path 7K is connected to the -Y direction side end of the upstream common flow path 61. An ink discharge path 13 is connected to the other end of the connection flow path 7K. The ink discharge path 13 is connected to one end of the connection channel 7L and one end of the connection channel 7M. The other end of the connection channel 7L is connected to the -Y direction side end of the first downstream common channel 62D. The other end of the connection channel 7M is connected to the -Y direction side end of the second downstream common channel 62E. Each connection channel 7H, 7I, 7J, 7K, 7L, 7M is formed such that its cross-sectional area is smaller than the cross-sectional area of the upstream common channel 61.

With the above configuration, a part of the ink supplied from the ink supply path 11 flows to the upstream common flow path 61 via the connection flow path 7H. The ink flowing into the upstream common flow path 61 passes through the upstream individual flow path 31, the pressure chamber 33, and the downstream individual flow path 34 to the first downstream common flow path 62D or the second downstream common flow path 62E. or flows to the ink discharge path 13 via the connection flow path 7K. The remainder of the ink supplied from the ink supply channel 11 flows into the first downstream common channel 62D via the connecting channel 7I or flows into the second downstream common channel 62E via the connecting channel 7J. The ink that has flowed into the first downstream common flow path 62D flows into the ink discharge path 13 via the connection flow path 7L. The ink that has flowed into the second downstream common flow path 62E flows into the ink discharge path 13 via the connection flow path 7M. The ink that has flowed into the ink discharge path 13 is returned to the upstream common flow path 61 via a second ink tank, a pump, a first ink tank, and the ink supply path 11 (not shown), respectively.

Each of the connection channels 7H, 7I, 7J, 7K, 7L, and 7M is configured to include at least one step. That is, each of the connection channels 7H, 7I, 7J, 7K, 7L, and 7M has an upper downward step 72, an upper upward step 73, a lower downward step 75, and a lower upward step, respectively, although they are not shown in FIG. 9B. It is configured to include a step 76.

With the above configuration, when ink flows through each of the connecting channels 7H, 7I, 7J, 7K, 7L, and 7M, air bubbles flow through each corner 723, 733, 753, 763 of each step 72, 73, 75, 76. It is stored in a predetermined area nearby.

As shown in FIG. 9A or 9B, the arrangement of the nozzle rows, the upstream common flow path 61, the downstream common flow path 62, the first downstream common flow path 62D, and the second downstream common flow path 62E, both ends of the upstream common flow path 61, the downstream common flow path 62, the first downstream common flow path 62D, and the second downstream common flow path 62E are connected to a connecting flow having a step. By connecting the inkjet heads through channels, it is possible to reduce the size of the inkjet head, and also to suppress production costs and fluid crosstalk.

[Fifth embodiment]
Next, a fifth embodiment of the present disclosure will be described. In the fifth embodiment, a method for forming a connecting channel will be described. FIG. 10 is an explanatory diagram of a method for forming a connecting channel.

Although the connecting channels having the steps shown in the first to fourth embodiments can be formed by machining, it is difficult to easily form the steps by machining, and the processing cost increases. For this reason, it is preferable to form a connection channel having a step in the channel plate 30 by taking advantage of the characteristics of the inkjet head in which the channel plate 30 (see FIG. 2) is formed in a layered structure. By forming through holes in each layer constituting the flow path plate 30 and stacking the layers so that the through holes of each layer partially overlap, a connecting flow path having a step can be formed.

For example, in order to form the connection channels 7C and 7D of the fourth embodiment shown in FIG. 8A, the channel plate 30 is constructed using the first to fifth layers 81 to 85 shown in FIG. 10. When forming the channel plate 30, the first layer 81, the second layer 82, the third layer 83, the fourth layer 84, and the fifth layer 85 are laminated in this order from the bottom.

In the fifth layer 85, a first connection channel through hole 851 forming the connection channel 7C and a second connection channel through hole 852 forming the connection channel 7D are formed. The first connection flow path through hole 851 is formed so as to at least partially overlap the second upstream common flow path portion 12 of the housing portion 10 (see FIG. 2). The second connection channel through hole 852 is formed so as to at least partially overlap the second downstream common channel section 14 of the housing section 10 .

The fifth layer 85 also includes a pressure chamber through hole 853 that constitutes the pressure chamber 33 and a first common flow path through hole 854 that constitutes the first upstream common flow path section 32 (see FIG. 2). , and a second common flow path through hole 855 constituting the first downstream common flow path portion 35 (see FIG. 2). The second upstream common flow path section 12 is formed so that its length in the X-axis direction and the Y-axis direction is longer than the length of the first common flow path through hole 854 in the X-axis direction and the Y-axis direction. has been done. The second downstream common flow path portion 14 is formed so that its length in the X-axis direction and the Y-axis direction is longer than the length of the second common flow path through hole 855 in the X-axis direction and the Y-axis direction. has been done. Therefore, the first and second connection channel through holes 851 and 852 are not connected to the first and second common channel through holes 854 and 855, but the second upstream common channel section 12 or the second upstream common channel section 12 or It is connected to the first and second common flow path through holes 854 and 855 via the two downstream common flow path portions 14 .

The fourth layer 84 is formed with a first connection channel through-hole 841 that constitutes the connection channel 7C and a second connection channel through-hole 842 that constitutes the connection channel 7D. The first connection flow path through hole 841 is formed so as to partially overlap the first connection flow path through hole 851 of the fifth layer. The second connection flow path through hole 842 is formed so as to partially overlap the second connection flow path through hole 852 in the fifth layer. Further, the fourth layer 84 is formed with a pressure chamber through hole 843 that constitutes the pressure chamber 33 and each of the individual channels 31 and 34 (see FIG. 2). The pressure chamber through hole 843 is formed so as to partially overlap the pressure chamber through hole 853 and the first and second common flow path through holes 854 and 855 of the fifth layer 85 .

In the third layer 83, a first connection channel through hole 831 forming the connection flow path 7C and a second connection flow path through hole 832 forming the connection flow path 7D are formed. The first connection flow path through hole 831 is formed so as to partially overlap the first connection flow path through hole 841 of the fourth layer. The second connection flow path through hole 832 is formed so as to partially overlap the second connection flow path through hole 842 in the fourth layer. Further, the third layer 83 includes a pressure chamber through hole 833 forming the pressure chamber 33, a first common flow path through hole 834 forming the first upstream common flow path section 32, and a first downstream side through hole 834 forming the first upstream common flow path section 32. A second common flow path through hole 835 constituting the common flow path portion 35 is formed. Each of the through holes 833, 834, and 835 is formed so that a portion thereof overlaps with the pressure chamber through hole 843 of the fourth layer 84.

In the second layer 82, a first connection channel through hole 821 forming the connection channel 7C is formed. The first connection flow path through hole 821 is formed so as to partially overlap the first connection flow path through hole 831 of the third layer. The second layer 82 also includes a silo part through hole 823 that constitutes the silo part 36 (see FIG. 2), and a first common flow passage through hole 824 that constitutes the first upstream common flow passage part 32. , and a second common flow path through hole 825 constituting the first downstream common flow path portion 35. The silo portion through hole 823 is formed so as to overlap the pressure chamber through hole 833 of the third layer 83 . The first and second common flow path through holes 824 and 825 are formed to overlap the first and second common flow path through holes 834 and 835 of the third layer 83, respectively.

In the first layer 81, a silo part through hole 813 that constitutes the silo part 36 is formed. The silo part through hole 813 is formed so as to overlap the silo part through hole 823 of the second layer 82 .

Each connection channel through hole 821, 831, 832, 841, 842, 851, 852 corresponds to the first through hole of the present disclosure, and each pressure chamber through hole 833, 843, 853 corresponds to the first through hole of the present disclosure. This corresponds to 2 through holes. Note that in FIG. 10, the first layer 81 does not have through holes for the first and second connection channels that constitute the connection channels 7C and 7D; By forming flow path through holes, the difference in level between the connecting flow paths 7C and 7D may be made deeper. In this case, in order to prevent ink from leaking from the first layer 81, a groove having a bottom may be formed instead of a through hole. Further, in order to increase the flow resistance of not only the first layer 81 but also the connection flow path 7C, for example, a groove having a bottom may be formed in place of the first connection flow path through hole 821 of the second layer 82. Also good. Further, in order to make the angle of the concave corner of each step 90 degrees or less, it is preferable to form each connection channel through hole 851, 852, 841, 842, 831, 832, 821 by etching. . In addition, the size, shape, or number of the through holes 851, 852, 841, 842, 831, 832, and 821 for each connection channel in the first layer 81 to the fifth layer 85 are merely examples, and the connection channel 7C , 7D or the flow path resistance of the connection channels 7C and 7D.

[Sixth embodiment]
Next, a sixth embodiment of the present disclosure will be described. In the sixth embodiment, preferred forms of the connection flow path and the individual flow paths will be described.

As shown in FIGS. 7A, 8A, 9A, and 9B, the upstream common flow path 61 and the downstream common flow path 62 are connected by connection flow paths 7C, 7E, 7F, 7I, and 7J. In this case, the ratio of the amount of ink flowing into the connection channels 7C, 7E, 7F, 7I, and 7J is determined by the channel resistance of the connection channels 7C, 7E, 7F, 7I, and 7J, and the individual channels 31 and 34 for each nozzle 41. is determined depending on the ratio of the flow path resistance (for example, the sum of the flow path resistance of the upstream individual flow path 31 and the flow path resistance of the downstream individual flow path 34). This is because at least a portion of the connection channels 7C, 7E, 7F, 7I, and 7J, the upstream individual channel 31, and the downstream individual channel 34 are arranged in parallel.

For example, if the ink flow rate of one connecting channel 7C is larger than the ink flow rate of each individual channel 31, 34 (one individual channel 31 or one individual channel 34), the individual channel 31 , 34 decreases, the drying prevention function of the nozzle 41 decreases. On the other hand, if the ink flow rate of one connecting flow path 7C is lower than the ink flow rate of each individual flow path 31, 34, the force for discharging air bubbles accumulated in areas other than the corners 723, 733, 753, 763 will be weakened. , it may not be possible to store air bubbles. That is, there is a problem in that the power of the connecting flow path 7C to discharge air bubbles is weakened, and the variation in the amount of air bubbles increases over time. For this reason, it is preferable that the ink flow rate of one connecting flow path 7C be approximately the same as the ink flow rate of each individual flow path 31, 34 communicating with each nozzle 41.

In order to make the ink flow rate of one connecting flow path 7C and the ink flow rate of each individual flow path 31, 34 about the same level, the flow path resistance of each individual flow path 31, 34 for each nozzle 41 is set as R1, and 1 When the flow path resistance of the connection flow path 7C is R2, it is preferable that the connection flow path 7C and each of the individual flow paths 31 and 34 are formed so as to satisfy the following equation (1). This is because if the following formula (1) is not satisfied, the above-mentioned problem will become apparent to a level that cannot be ignored.

(R2/5)<R1<(R2×5)…(1)
In order to satisfy the above formula (1), as shown in FIG. 10, the connecting channel 7C is formed using a layer for forming the upstream individual channel 31 and the downstream individual channel 34. It is preferable that The reason is explained below.

In order to increase the flow resistance of the individual channels 31, 34, the thickness of the layer forming the individual channels 31, 34 (the fourth layer 84 in the example shown in FIG. 10) is made thinner than the other layers. It is preferable. In this case, in order to make the flow path resistance of the connecting channel 7C equal to that of the individual channels 31 and 34 by using a layer thicker than the fourth layer 84, the length of the connecting channel 7C in the ink flow direction must be adjusted. Since it is necessary to have a suitable length, it becomes difficult to miniaturize the inkjet head. In order to increase the flow resistance of the individual channels 31, 34, when the thickness of the layer forming the individual channels 31, 34 (the fourth layer 84 in the example shown in FIG. 10) is thinner than the other layers, By making the length of the fourth layer 84 in the X-axis direction equal to that of the individual channels 31 and 34, it is easy to make the channel resistance of the connecting channel 7C equal to that of the individual channels 31 and 34. Therefore, it becomes easy to satisfy the above formula (1) while satisfying the demand for miniaturization.

For the above reasons, the connecting channels 7C, 7E, 7F, 7I, and 7J are preferably formed using the layers that form the individual channels 31 and 34. In addition, when forming the connecting channels 7C, 7E, 7F, 7I, and 7J without using the layer forming the individual channels 31 and 34 for some design reason, the configuration is such that the above formula (1) is satisfied. It is preferable.

[Seventh embodiment]
Next, a seventh embodiment of the present disclosure will be described. In the seventh embodiment, preferred forms of the upstream common flow path 61 and the downstream common flow path 62 will be described. FIG. 11A is a cross-sectional view in the YZ plane near the upstream common flow path. FIG. 11B is a cross-sectional view in the YZ plane near the downstream common flow path. Note that the same components as in the first embodiment are given the same names and symbols, and the explanation may be simplified or omitted.

As described above, the air bubbles introduced from the ink supply path 11 or the nozzle 41 are stored at the corners of the step of the connection flow path, but the air bubbles in excess of the allowable storage amount at the corners are stored in the ink supply. Preferably, the ink is quickly discharged to the outside of the inkjet head via the ink discharge channel 11 or the ink discharge channel 13. At this time, if air bubbles accumulate in the upstream common flow path 61 or the downstream common flow path 62, this becomes a factor that causes variations in the ink ejection state. Further, if air bubbles enter the upstream common flow path 61 or the downstream common flow path 62, this becomes a factor that further worsens the variation in the ink ejection state. Therefore, it is necessary for the upstream side common flow path 61 or the downstream side common flow path 62 to quickly discharge the bubbles to the outside without accumulating them.

Therefore, as shown in FIG. 11A, it is preferable that the upper surface 611 of the upstream common flow path 61 be formed by an inclined surface that continuously descends as it moves away from the connection site with the ink supply path 11. A connection flow path 7N is connected to the upstream end of the upstream common flow path 61. A connecting flow path 7P is connected to the downstream end of the upstream common flow path 61. With such a configuration, for example, when air bubbles injected from the ink supply path 11 remain in the upstream common flow path 61 without being discharged from the connection flow path 7P or the connection flow path 7N, the air bubbles located near the upper surface 611 can be discharged through the ink supply path 11 by buoyancy.

Further, as shown in FIG. 11B, it is preferable that the upper surface 621 of the downstream common flow path 62 is formed by an inclined surface that rises continuously as it approaches the connection site with the ink discharge path 13. A connecting flow path 7Q is connected to the upstream end of the downstream common flow path 62. A connecting flow path 7R is connected to the downstream end of the downstream common flow path 62. With such a configuration, for example, when air bubbles injected from the ink supply path 11 remain in the downstream common flow path 62 without being discharged from the connection flow path 7Q or the connection flow path 7R, the air bubbles located near the upper surface 621 can be discharged through the ink discharge path 13 by buoyancy.

Note that if the inclination angle of the upper surface 611 of the upstream common channel 61 and the upper surface 621 of the downstream common channel 62 is too small, the force to discharge air bubbles by buoyancy will be weakened, and if it is too large, the size of the inkjet head will increase. , for example, it is preferable to form it so that it is about 1 degree or more and 5 degrees or less. There is no particular limitation on the method of machining the top surface 611 of the upstream common flow path 61 and the top surface 621 of the downstream common flow path 62, but for example, machining may be performed using a ball end mill while continuously changing the cutting depth. An example of how to do this can be given.

[Modified example]
Note that the present disclosure is not limited to the above embodiments, and can be modified as appropriate without departing from the spirit.

For example, although a configuration in which the connection flow path includes an upper downward step 72, an upper upward step 73, a lower downward step 75, and a lower upward step 76 is illustrated, one, two, or , may include only three steps.

For example, as a modification of the configuration shown in FIG. 3A, instead of the connection flow path 7, a connection flow path 7S may be arranged as shown in FIG. 12A. A side wall surface constituting a side surface of the connection channel 7S on the +X direction side includes two steps 77. A side wall surface constituting a side surface of the connection flow path 7S on the -X direction side is configured to include two steps 78. Even in such a configuration, the main flow line of the ink in the connecting channel 7S can be made to flow so as to avoid the corners 773, 783 of the steps 77, 78, as shown by the arrow D1. , air bubbles can be stored in a predetermined area near the corners 773, 783 of the steps 77, 78.

For example, as shown in FIG. 12B, a protrusion 79 may be formed in the connection channel 7T. In this case, the connection channel 7T is configured to form a first wall portion 71T that guides ink in the −Y direction (first direction) and a recessed corner portion 793 at the downstream end of the first wall portion 71T. A second wall surface portion 791 of the protrusion 79 is connected and guides the ink in the -Z direction (second direction). The corner portion 793 corresponds to the bubble storage portion of the present disclosure. The first wall part 71T corresponds to the first part of the present disclosure, and the second wall part 791 corresponds to the second part of the present disclosure. Even in such a configuration, as shown by the arrow D1, the main flow line of the ink in the connecting channel 7T can be made to flow so as to avoid the corner 793, and the air bubbles can be caused to flow around the corner 793. can be stored in a predetermined range of areas.

According to the inkjet head of the present disclosure, variations in the state of ink ejection can be suppressed.

The present disclosure can be widely used in inkjet heads and printing equipment equipped with inkjet heads.

1 Inkjet head 7, 7A, 7B, 7C, 7D, 7E, 7F, 7G, 7H, 7I, 7J, 7K, 7L, 7M, 7N, 7P, 7Q, 7R, 7S, 7T Connection channel 10 Housing part 11 Ink Supply path 12 Second upstream common flow path 13 Ink discharge path 14 Second downstream common flow path 20 Vibration plate 21 Upstream opening 22 Downstream opening 24 Convex portion 30 Channel plate 31 Upstream individual flow path 32 First upstream common flow path section 33 Pressure chamber 34 Downstream individual flow path 35 First downstream common flow path section 36 Silo section 40 Nozzle plate 41 Nozzle 50 Pressure variation section 51 Base section 52 Piezoelectric element 53 Substrate 61 Upstream side Common channel 62 Downstream common channel 62A First section 62B Second section 62C Third section 62D First downstream common channel 62E Second downstream common channel 70 Thin film member 71, 71A, 71B, 71C, 71D Top Wall surface 71T First wall portion 72, 73, 75, 76, 77, 78 Step 74, 74A, 74B, 74C, 74D Lower wall surface 79 Projection 81 First layer 82 Second layer 83 Third layer 84 Fourth layer 85 5 layers 611, 621 Upper surface 701 Through hole for channel 702 Upper surface 703 Lower surface 721, 731 First upper wall section 722, 732 Second upper wall section 723, 733, 753, 763, 773, 783 Corner section 751, 761 1st Lower wall part 752, 762 Second lower wall part 791 Second wall part 793 Corner part 813 Through hole for silo part 823 Through hole for silo part 821, 831, 841, 851 Through hole for first connection channel 824, 834, 854 Through hole for first common flow path 825,835,855 Through hole for second common flow path 832,842,852 Through hole for second connection flow path 833,843,853 Through hole for pressure chamber B Air bubble

Claims (14)

1. a plurality of pressure chambers communicating with nozzles that eject ink;
   a first common flow path communicating with the plurality of pressure chambers;
   a connecting flow path connected to the first common flow path,
   The connection channel has a bubble storage section that stores bubbles.
   inkjet head.
2. The connection flow path is
   a first part that guides the ink in a first direction;
   a second part connected to the first part and guiding the ink in a second direction intersecting the first direction;
   The bubble storage part is a corner part where the first part and the second part are connected.
   The inkjet head according to claim 1.
3. The bubble storage section is a step formed in the connection channel,
   The inkjet head according to claim 1.
4. The connection channel is formed by stacking a plurality of plate-like members each having a first through hole.
   The inkjet head according to claim 2.
5. At least one of the plurality of plate-like members has a second through hole that forms the plurality of pressure chambers.
   The inkjet head according to claim 4.
6. The connection flow path is located between an ink supply path that supplies the ink to the first common flow path and the first common flow path.
   The inkjet head according to any one of claims 1 to 5.
7. The connecting flow path is located between an ink discharge path that discharges the ink and the first common flow path.
   The inkjet head according to any one of claims 1 to 5.
8. further comprising a second common flow path communicating with the plurality of pressure chambers,
   One end of the connection flow path is connected to the first common flow path, and the other end of the connection flow path is connected to the second common flow path.
   The inkjet head according to any one of claims 1 to 5.
9. The connecting flow path is a flow path different from the flow path of the ink flowing from the first common flow path to the second common flow path via the plurality of pressure chambers.
   The inkjet head according to claim 8.
10. Each of the plurality of pressure chambers further includes a plurality of individual channels that individually communicate with the first common channel,
    Each individual flow path and the connection flow path are formed to satisfy the following formula (1),
    (R2/5)<R1<(R2×5)…(1)
    R1: Channel resistance in the individual channel R2: Channel resistance in the connecting channel The inkjet head according to any one of claims 1 to 5.
11. further comprising a second common flow path communicating with the plurality of pressure chambers,
    The connection flow path is located between an ink supply path that supplies the ink to the first common flow path and the second common flow path, and is connected to the second common flow path.
    The inkjet head according to any one of claims 1 to 5.
12. further comprising a second common flow path communicating with the plurality of pressure chambers,
    The connection flow path is located between the ink discharge path that discharges the ink and the second common flow path, and is connected to the second common flow path.
    The inkjet head according to any one of claims 1 to 5.
13. The upper surface of the first common flow path is higher upstream than downstream in the ink flow direction.
    The inkjet head according to claim 1.
14. further comprising a second common flow path communicating with the plurality of pressure chambers,
    The upper surface of the second common flow path is higher downstream than upstream in the ink flow direction.
    The inkjet head according to claim 1.

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