Liquid dispensing head, liquid dispensing device

Abstract

To provide a liquid dispensing head and liquid dispensing device that can stably dispense liquid in a liquid circulation system. [Solution] The liquid discharge head of the embodiment includes a plurality of pressure chambers each communicating with a nozzle, a plurality of upstream resistance passages and downstream resistance passages each communicating with a pressure chamber, an upstream common liquid chamber, a downstream common liquid chamber, a bypass passage, a bypass resistance passage, and upstream and downstream pressure dampers. The upstream common liquid chamber has one end communicating with an upstream liquid port and extends in the direction of the arrangement of the plurality of pressure chambers while communicating with the plurality of upstream resistance passages. The downstream common liquid chamber has one end communicating with a downstream liquid port and extends in the direction of the arrangement of the plurality of pressure chambers while communicating with the plurality of downstream resistance passages. The bypass passage connects the other end of the upstream common liquid chamber to the downstream common liquid chamber. The bypass resistance passage is provided in the bypass passage. The upstream pressure damper is provided on the upstream side of the bypass resistance passage. The downstream pressure damper is provided on the downstream side of the bypass resistance passage.

Description

Technical Field

[0001] Embodiments of the present invention relate to a liquid ejection head and a liquid ejection device.

Background Art

[0002] A liquid ejection head for supplying a predetermined amount of liquid to a predetermined position is known. The liquid ejection head is mounted on, for example, an inkjet printer, a 3D printer, a dispensing device, etc. An inkjet printer ejects ink droplets from an inkjet head to form an image or the like on the surface of a recording medium. A 3D printer ejects droplets of a modeling material from a modeling material ejection head and cures them to form a three-dimensional object. A dispensing device ejects droplets of a sample and supplies a predetermined amount to a plurality of containers or the like.

[0003] The liquid ejection head has a plurality of channels for ejecting liquid. Each channel includes a nozzle for ejecting liquid, a pressure chamber communicating with the nozzle, and an actuator for changing the volume of the pressure chamber. The liquid ejection head selects a channel for ejecting liquid from among the plurality of channels, and applies a drive voltage to the actuator of the selected channel to eject the liquid.

[0004] After liquid ejection, a liquid ejection head retains vibrations (meniscus vibrations) determined by the surface tension of the liquid meniscus within the nozzle and the mass of the liquid. For example, high-speed liquid ejection heads need to quickly suppress these vibrations, and for this purpose, resistance channels are provided before and after the pressure chamber. However, when attempting to create a liquid circulation head, these resistance channels hinder liquid circulation. In particular, in multi-nozzle heads with multiple channels, if the upstream-downstream ratio of the resistance channels does not match between channels, a pressure difference will occur between channels, degrading print quality. That is, in channels with relatively low upstream flow resistance, ink tends to spread outwards from the edge of the meniscus, and in channels with relatively low downstream flow resistance, air is more likely to be mixed in. Therefore, it is difficult to maintain a state across all channels where ink does not spread outwards from the edge of the meniscus and air is not mixed in. To avoid these problems, the circulation flow rate must be reduced, but if the circulation flow rate is low, the liquid stirring effect due to the circulation flow is small, and the effect of uniformizing the head temperature due to the circulation flow is also small.

[0005] In a multi-nozzle head, the total liquid discharge flow rate changes rapidly because the number of channels discharging liquid simultaneously changes. Furthermore, pulsation components from the liquid circulation pump may remain in the liquid flow rate through the liquid supply path. Therefore, there is a need to investigate methods to mitigate the abrupt changes in the liquid discharge head's supply pressure caused by these factors. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2024-21621 [Patent Document 2] Japanese Patent Publication No. 2023-077729 [Patent Document 3] Japanese Patent Publication No. 2017-159561 [Patent Document 4] Japanese Patent Publication No. 2019-59047 [Overview of the project] [Problems that the invention aims to solve]

[0007] The problem that this invention aims to solve is to provide a liquid discharge head and a liquid discharge device that can stably discharge liquid in a liquid circulation system. [Means for solving the problem]

[0008] The liquid discharge head of an embodiment of the present invention comprises a plurality of pressure chambers, a plurality of upstream resistance passages, an upstream common liquid chamber, a plurality of downstream resistance passages, a downstream common liquid chamber, a bypass passage, a bypass resistance passage, an upstream pressure damper, and a downstream pressure damper. The plurality of pressure chambers each communicate with a nozzle. The plurality of upstream resistance passages each communicate with the pressure chambers. The upstream common liquid chamber has one end communicating with an upstream liquid port and extends in the direction of the arrangement of the plurality of pressure chambers while communicating with the plurality of upstream resistance passages. The plurality of downstream resistance passages each communicate with the pressure chambers. The downstream common liquid chamber has one end communicating with a downstream liquid port and extends in the direction of the arrangement of the plurality of pressure chambers while communicating with the plurality of downstream resistance passages. The bypass passage connects the other end of the upstream common liquid chamber to the downstream common liquid chamber. The bypass resistance passage is provided in the bypass passage. The upstream pressure damper is provided upstream of the bypass resistance passage. The downstream pressure damper is installed downstream of the bypass resistance flow path. [Brief explanation of the drawing]

[0009] [Figure 1] This is an overall configuration diagram of an inkjet printer equipped with an inkjet head according to the first embodiment. [Figure 2] The above is a perspective view of the inkjet head. [Figure 3] This is a partially enlarged cross-sectional view of the head portion of the inkjet head shown above. [Figure 4] This is a partially enlarged cross-sectional view of the head portion of the inkjet head shown above. [Figure 5] These are a perspective view and a cross-sectional view of the head portion of the inkjet head shown above, with some parts enlarged. [Figure 6]It is a plan view of each layer of the head portion of the inkjet head described above. [Figure 7] It is an overall configuration diagram of the ink circulation device of the inkjet head described above. [Figure 8] It is the drive circuit of the inkjet head described above. [Figure 9] It is the drive waveform applied to the piezoelectric actuator of the inkjet head described above. [Figure 10] It is an operation explanatory diagram of the piezoelectric actuator to which the drive waveform is applied. [Figure 11] It is a plan view of each layer of the head portion of the inkjet head of the second embodiment. [Figure 12] It is a modified example of the ink circulation device described above. [Figure 13] It is a plan view of each layer of the head portion of the inkjet head of the third embodiment. [Figure 14] It is a plan view of each layer of the head portion of the inkjet head of the fourth embodiment. [Figure 15] It is a plan view of each layer of the head portion of the inkjet head of the fifth embodiment. [Figure 16] It is a plan view of each layer of the head portion of the inkjet head of the sixth embodiment. [Figure 17] It is a plan view of each layer of the head portion of the inkjet head of the seventh embodiment.

Embodiments for Carrying Out the Invention

[0010] Hereinafter, a liquid ejection head according to an embodiment will be described in detail with reference to the accompanying drawings. In each figure, the same components are denoted by the same reference numerals.

[0011] (First Embodiment) As an example of an image forming apparatus equipped with the liquid ejection head of the first embodiment, an inkjet printer 10 that prints an image on a recording medium will be described. FIG. 1 shows a schematic configuration of the inkjet printer 10. The inkjet printer 10 includes, inside a housing 11, a cassette 12 that stores a sheet S, which is an example of a recording medium, an upstream conveyance path 13 of the sheet S, a conveyance belt 14 that conveys the sheet S taken out from the cassette 12, a plurality of inkjet heads 100 to 103 that eject ink droplets toward the sheet S on the conveyance belt 14, a downstream conveyance path 15 of the sheet S, a discharge tray 16, and a control board 17. An operation unit 18, which is a user interface, is arranged on the upper side of the housing 11.

[0012] Image data to be printed on the sheet S is generated, for example, by a computer 200 that is an external connection device. The image data generated by the computer 200 is sent to the control board 17 of the inkjet printer 10 through a cable 201 and connectors 202, 203.

[0013] A pickup roller 204 supplies the sheets S from the cassette 12 to the upstream conveyance path 13 one by one. The upstream conveyance path 13 is composed of a pair of feed rollers 131, 132 and sheet guide plates 133, 134. The sheet S is sent to the upper surface of the conveyance belt 14 via the upstream conveyance path 13. Arrow 104 in the figure indicates the conveyance path of the sheet S from the cassette 12 to the conveyance belt 14.

[0014] The conveyance belt 14 is a net-like endless belt having a large number of through holes formed on its surface. Three rollers, a drive roller 141 and driven rollers 142, 143, rotatably support the conveyance belt 14. A motor 205 rotates the drive roller 141 to rotate the conveyance belt 14. The motor 205 is an example of a driving device. Arrow 105 in the figure indicates the rotation direction of the conveyance belt 14. A negative pressure container 206 is arranged on the back side of the conveyance belt 14. The negative pressure container 206 is connected to a decompression fan 207. The fan 207 creates a negative pressure inside the negative pressure container 206 by the airflow formed, and adsorbs and holds the sheet S on the upper surface of the conveyance belt 14. Arrow 106 in the figure indicates the flow of the airflow.

[0015] Inkjet heads 100-103, which are examples of liquid ejection heads, are positioned opposite a sheet S held by suction on a transport belt 14, with a small gap of, for example, 1 mm between them. Each inkjet head 100-103 ejects droplets of ink toward the sheet S. The inkjet heads 100-103 print an image as the sheet S passes below them. Each inkjet head 100-103 has the same structure except that it ejects a different color of ink. The ink colors are, for example, cyan, magenta, yellow, and black.

[0016] Ink is supplied to each inkjet head 100-103 by each ink circulation device 341-344. The detailed configuration of ink circulation devices 341-344 will be described later (see Figure 7). In Figure 1, for ease of drawing, ink circulation devices 341-344 are shown with dashed lines.

[0017] After image formation, the sheet S is sent from the conveyor belt 14 to the downstream conveyor path 15. The downstream conveyor path 15 consists of feed roller pairs 151, 152, 153, and 154, and sheet guide plates 155 and 156 that define the conveying path of the sheet S. The sheet S is sent via the downstream conveyor path 15 to the discharge tray 16 from the discharge port 157. In the figure, arrow 107 indicates the conveying path of the sheet S.

[0018] Next, we will explain the configuration of inkjet heads 100 to 103. The following explanation of inkjet head 100 is based on Figures 2 to 6, but inkjet heads 101 to 103 have the same structure as inkjet head 100.

[0019] As shown in Figure 2, the inkjet head 100 includes a head unit 2, which is an example of a liquid ejection unit. The head unit 2 is connected to a flexible printed circuit board 21, which is an example of a film wiring board. The flexible printed circuit board 21 is connected to a printed circuit board 22, which is an example of a relay board. The head unit 2 includes a nozzle plate 23, which is an example of a nozzle unit. The ink-circulating head unit 2 is connected to an ink circulation device 341 via an ink supply path 311 and an ink discharge path 331.

[0020] The nozzles 24 of each channel that eject ink are arranged along the first direction of the nozzle plate 23, for example, the X direction. The nozzle density is set to a range of, for example, 150 to 1200 dpi. The nozzles 24 are not limited to a single row, but may be arranged in multiple rows. The detailed configuration of the head unit 2 will be described later.

[0021] The flexible printed circuit board 21 is a flexible printed circuit board made of a synthetic resin film such as polyimide. The flexible printed circuit board 21 is equipped with a driver chip, which is an integrated circuit (IC) 3 (hereinafter referred to as the driver IC). The printed circuit board 22 is a rigid through-hole board made of multiple layers of glass fiber-reinforced epoxy resin and copper wiring layers. The driver IC 3, which acts as the control unit for the inkjet head 100, temporarily stores the print data sent from the control board 17, which is equipped with a CPU that acts as the control unit for the inkjet printer 10, via the printed circuit board 22, and provides drive signals to each channel to eject ink at predetermined timings.

[0022] Figures 3 to 6 are partial cross-sectional views of the head section 2. The nozzle plate 23 is bonded to one surface of the pressure chamber substrate 4. The nozzle plate 23 is a rectangular plate formed from, for example, a resin such as polyimide or a metal such as stainless steel. The diaphragm 41 is bonded to one surface of the pressure chamber substrate 4 opposite to the nozzle plate 23. The diaphragm 41 is flexible and deforms when an external force is applied. The diaphragm 41 is a rectangular plate formed from, for example, a flexible polyimide film or metal.

[0023] The pressure chamber 42 is formed in the pressure chamber substrate 4. Multiple pressure chambers 42 are arranged at the position of each nozzle 24 and communicate with each nozzle 24. The pressure chamber 42 is formed in a groove shape along a second direction, for example, the Y direction. As an example, the pressure chamber 42 has a rectangular opening formed in the pressure chamber substrate 4 that penetrates in a third direction, for example, the Z direction, and the opening on both sides in the Z direction is closed by the nozzle plate 23 and the diaphragm 41, respectively, to form a space for filling with ink.

[0024] In an ink-circulating print head, one end (upstream side) of each pressure chamber 42 in the Y direction is connected to an upstream common liquid chamber 44 via an upstream resistance passage 43. The upstream common liquid chamber 44 is formed to extend in the direction of arrangement of the pressure chambers 42 (X direction), with each upstream resistance passage 43 connected sequentially to its side. The upstream common liquid chamber 44 is an ink supply manifold that supplies ink to each pressure chamber 42 via each upstream resistance passage 43. As an example, the upstream common liquid chamber 44 is formed by creating an opening in the pressure chamber substrate 4 that penetrates in the Z direction, and blocking the openings on both sides in the Z direction with a nozzle plate 23 and a diaphragm 41, respectively, to form a space through which ink flows. The upstream ink port 45 that supplies ink to the upstream common liquid chamber 44 is provided on one side in the arrangement direction of the multiple pressure chambers 42, on one end in the X direction in the example shown in the figure. An ink supply passage 311 is connected to the upstream ink port 45 (see Figure 2). The upstream ink port 45 is an example of an upstream liquid port.

[0025] The other end (downstream side) of each pressure chamber 42 in the Y direction is connected to a downstream common liquid chamber 47 via a downstream resistance passage 46. The downstream common liquid chamber 47 is formed to extend in the direction of arrangement of the pressure chambers 42 (X direction), with each downstream resistance passage 46 connected sequentially to its side. The downstream common liquid chamber 47 is an ink discharge manifold through which the ink discharged from each pressure chamber 42 via each downstream resistance passage 46 flows in common. As an example, the downstream common liquid chamber 47 is formed by creating an opening that penetrates in the Z direction in the pressure chamber substrate 4, and blocking the openings on both sides in the Z direction with a nozzle plate 23 and a diaphragm 41, respectively, to form a space through which the ink flows. The downstream ink port 48, which discharges ink from the downstream common liquid chamber 47 to the head unit 2, is provided on one end in the same X direction as the upstream ink port 45. An ink discharge passage 331 is connected to the downstream ink port 48 (see Figure 2). The downstream ink port 48 is an example of a downstream liquid port.

[0026] Each upstream resistance channel 43 is formed to have a smaller channel cross-section and thus flow resistance, for example, by being narrower than the width of the pressure chamber 42 in the X direction. Similarly, each downstream resistance channel 46 is formed to have a smaller channel cross-section and thus flow resistance, for example, by being narrower than the width of the pressure chamber 42 in the X direction. In an ink circulation head, the upstream resistance channels 43, the pressure chamber 42, and the downstream resistance channels 46 form a pressure chamber circulation channel.

[0027] Furthermore, the channel cross-sections of the upstream resistance channel 43 and the downstream resistance channel 46 may be reduced by narrowing the width in the Z direction instead of the X direction, or by narrowing the width in both the X and Z directions. Also, it is preferable, but not limited to, that the upstream resistance channel 43 and the downstream resistance channel 46 are formed along the central axis in the Y direction of the pressure chamber 42. In other words, it is sufficient that the channel cross-section of the ink in the upstream resistance channel 43 and the downstream resistance channel 46 is smaller than the channel cross-section of the pressure chamber 42. Therefore, the shape of the channel cross-section of the upstream resistance channel 43 and the downstream resistance channel 46 is not limited to a rectangle. Furthermore, it is preferable, but not limited to, that each upstream resistance channel 43 has the same shape as the other channels. Similarly, it is preferable, but not limited to, that each downstream resistance channel 46 has the same shape as the other channels. It is preferable, but not limited to, that the upstream resistance channel 43 and the downstream resistance channel 46 have a symmetrical shape in the Y direction via the pressure chamber 42. However, in order to prevent pressure differences from occurring between channels, the upstream-downstream ratio of the resistance flow paths (43, 46) of each channel is made to match.

[0028] The bypass channel 49 is located on one side of the arrangement direction of the multiple pressure chambers 42, on the other end in the X direction in the example shown in the figure. That is, it is located on the opposite side from the upstream ink port 45 and the downstream ink port 48. The bypass channel 49 is a channel that bypasses ink by connecting the other ends of the upstream common liquid chamber 44 and the downstream common liquid chamber 47.

[0029] Specifically, the upstream common liquid chamber 44 branches out and connects to each upstream resistance channel 43 sequentially toward the other end in the direction of arrangement of the pressure chambers 42, and beyond the last upstream resistance channel 43 it connects to one end of the bypass channel 49. The downstream common liquid chamber 47 connects to the other end of the bypass channel 49 and then merges and connects to each downstream resistance channel 46 sequentially toward the one end in the direction of arrangement of the pressure chambers 42, and beyond the last downstream resistance channel 46 it connects to the downstream ink port 48.

[0030] As an example, the bypass channel 49 is made into a flattened shape with a smaller width in the Z direction and a larger width in the X direction to facilitate the damping effect of the pressure damper (8,80) described later. A bypass resistance channel 81 is provided in the middle of the bypass channel 49. The bypass resistance channel 81 is made narrower than the width of the bypass channel 49 in the X direction, thereby reducing the channel cross-section and providing flow resistance. This allows the ink circulation flow to be formed not only in the bypass channel 49 but also in the pressure chamber circulation flow that supplies ink to each pressure chamber 42. The ratio of the total ink flow rate of the pressure chamber circulation flowing through each pressure chamber 42 to the ink flow rate of the bypass channel 49 can be adjusted by the dimensions (channel cross-section, channel length) of the bypass resistance channel 81. For example, if the channel cross-sectional area of ​​the bypass resistance channel 81 is increased and the flow resistance of the bypass channel 49 is decreased, more ink will flow through the bypass channel 49. Conversely, if the channel cross-sectional area of ​​the bypass resistance channel 81 is decreased and the flow resistance of the bypass channel 49 is increased, more ink will flow through each pressure chamber 42. At this time, the ink flow rate through each pressure chamber 42 is adjusted to be less than the ink flow rate discharged from each nozzle 24. Preferably, the ink flow rate supplied to the pressure chamber 42 is set to, for example, 0.6 times the ink flow rate discharged from the nozzle 24. The deficit is drawn in from the downstream common liquid chamber 47, as will be described later.

[0031] To compensate for any deficiency from the downstream common liquid chamber 47, the total flow rate of ink flowing through the bypass channel 49 and the flow rate of ink flowing through each channel from the inlet of each upstream resistance channel 43 to the outlet of each downstream resistance channel 46 is set to be equal to or greater than the total maximum discharge flow rate of ink discharged from each nozzle 24. This flow rate setting is performed, for example, by the ink circulation device 341. The maximum ink discharge flow rate is the total flow rate when ink is discharged from all discharge channels.

[0032] As an example, if the circulating flow rate of ink through the pressure chamber 42 is set to 0.6 times the discharge flow rate as described above, the flow resistance of the bypass channel 49 is set to be (6 / 14) times the parallel flow resistance of all channels passing through the pressure chamber 42, so that 1.4 times the discharge flow rate flows through the bypass channel. This setting is done, for example, by adjusting the dimensions (channel cross-section, channel length) of the bypass resistance channel 81. Then, if ink is circulated from the upstream ink port 45 to the downstream ink port 48 at, for example, twice the total maximum discharge flow rate, the circulating flow rate when ink is not being discharged will be in a ratio of 3:7 between the circulation path through each pressure chamber 42 and the bypass channel 49. At maximum discharge, ink flows backward from the downstream common liquid chamber 47 towards the pressure chamber 42, but since that amount of ink is supplied to the downstream common liquid chamber 47 from the bypass channel 49, ink does not flow backward from the downstream side beyond the downstream ink port 48, which may be contaminated with foreign matter or air bubbles.

[0033] The relationship between the flow rate of the ink circulation flow through the pressure chamber 42, that is, the flow rate that flows into the pressure chamber 42 when no ink is ejected from the nozzles 24, and the flow rate of the ink circulation flow through the bypass channel 49, is defined as the relationship a) to d) below, for example, with the maximum ejection flow rate, that is, the total amount of ink consumed when maximum continuous ejection is performed from all nozzles 24, set to 1. Pressure chamber 42 Bypass channel 49 Total ratio a) 0.6 0.4 1 6:4 b) 0.6 1.4 2 3:7 c) 0.2 0.8 1 1:4 d) 0.2 1.8 2 1:9 In the above cases b) and d), the total flow rate is larger than in a) and c), which is advantageous for temperature stability and preventing ink component sedimentation. In the cases a) and c), the total flow rate is smaller than in b) and d), making ink supply easier. In the cases c) and d), the pressure chamber circulation flow rate is smaller than in a) and b), so the effect of flow path resistance on nozzle back pressure is smaller, making it easier to stabilize nozzle back pressure. In the cases a) and b), the pressure chamber circulation flow rate is larger than in c) and d), making it easier to discharge foreign matter and air bubbles mixed into the pressure chamber 42 to the downstream side. In the order a), b), c), and d), the ratio of the flow rate of the bypass flow path 49 to the pressure chamber circulation flow rate is larger, so even if needle-shaped foreign matter is mixed into the supplied ink, it is difficult for it to be mixed into the pressure chamber 42. In all cases a), b), c), and d), the total flow rate is greater than 1, so even at maximum discharge, it is possible to prevent foreign matter in the ink from being drawn into the head unit 2 from the downstream ink port 48.

[0034] The ink circulation system is equipped with a pressure damper to suppress sudden pressure changes. The pressure damper comprises an upstream pressure damper 8 positioned upstream of the bypass resistance channel 81 and a downstream pressure damper 80 positioned downstream of the bypass resistance channel 81. In this embodiment, as an example, the bypass resistance channel 81 is positioned in the center of the bypass channel 49, and both the upstream pressure damper 8 and the downstream pressure damper 80 are provided within the bypass channel 49. The upstream pressure damper 8 and the downstream pressure damper 80 have the same basic structure. That is, one side of the bypass channel 49 opposite to the nozzle plate 23 in the Z direction is opened, and this opening is sealed with a flexible material 82 such as a thin polyimide film. The flexible material 82 is an example of a damper film. The flexible material 82 such as a polyimide film is an example of a flexible resin that covers the opening of the bypass channel 49. Both the upstream pressure damper 8 and the downstream pressure damper 80 are examples of membrane dampers. The upstream pressure damper 8 and the downstream pressure damper 80 can mitigate sudden pressure changes in the upstream common liquid chamber 44 and the downstream common liquid chamber 47 when the ink discharge rate changes rapidly, by allowing the soft material 82, which is a damper film, to flex.

[0035] In other words, especially with multi-nozzle heads that have multiple channels for ejecting ink, the flow rate of ejected ink can change abruptly depending on the printing content. For example, when printing a pattern like a line drawing with many blank spaces immediately after printing with all channels at full duty, the ink flow rate decreases abruptly. Conversely, when printing a pattern that starts from a blank space and then resumes full duty, the ink flow rate increases abruptly. Such abrupt changes in ink flow rate require the ink, which has mass, to stop or start abruptly, which changes the back pressure of the ejected ink. Changes in back pressure affect the behavior of the ejected ink and lead to a deterioration in print quality.

[0036] While pressure dampers have sometimes been used to absorb changes in ink back pressure, the ink-circulating inkjet head 100 has many flow paths, making it difficult to install a pressure damper in a simple configuration. Therefore, by installing an upstream pressure damper 8 and a downstream pressure damper 80 in the bypass flow path 49 as in this embodiment, the damping effect can be applied to both the upstream common liquid chamber 44 and the downstream common liquid chamber 47. If a pressure damper is only installed on the upstream side of the bypass resistance flow path 81, the downstream side will be affected by the upstream pressure damper via the bypass resistance flow path 81, resulting in a weaker damping effect.

[0037] Furthermore, providing the upstream pressure damper 8 and the downstream pressure damper 80 in the bypass channel 49, as in this embodiment, has the advantage of allowing a single flexible material 82 to be shared between the upstream and downstream pressure dampers 8 and 80. Additionally, because the upstream and downstream pressure dampers 80 are located in the bypass channel 49, it is easier to fill them with ink. Membrane-type pressure dampers function more efficiently the thinner and larger their surface area. Therefore, adjusting the width of the bypass channel 49 in the Z and X directions to create a flatter shape is preferable, as it increases the surface area of ​​the flexible material 82, which is the damper film. However, the location where the flexible material 82 is placed is not necessarily limited to the opening in the Z direction.

[0038] When a pressure damper is installed in the bypass channel 49, it is preferable that the flow rate of ink flowing through the bypass channel 49 be greater than or equal to the sum of the circulating flow rates of ink flowing through each pressure chamber 42. That is, in order for the pressure damper to function effectively, the dimensions (cross-sectional area and length) of the bypass resistance channel 81 are designed such that the flow resistance of the bypass channel 49 is less than or equal to the parallel flow resistance of all the channels flowing through the pressure chamber 42. The flow resistance of all the channels flowing through the pressure chamber 42 is the flow resistance of the multiple channels from the inlet of the upstream resistance channel 43 to the outlet of the downstream resistance channel 46. The parallel flow resistance is the reciprocal of the sum of the reciprocals of the flow resistances of all channels.

[0039] However, the bypass channel 49 is not limited to having a flattened cross-section; its width in the Z direction and X direction may be adjusted. The shape of the channel cross-section of the bypass channel 49 is not limited to a rectangle.

[0040] Figure 7 shows the overall configuration of the ink circulation device 341 that circulates and supplies ink to the inkjet head 100. The ink circulation device 341 is an example of a liquid circulation device for a liquid ejection head. Note that the ink circulation devices 342 to 344 that circulate and supply ink to the inkjet heads 101 to 103 have the same configuration as the ink circulation device 341. As shown in Figure 7, the ink circulation device 341 consists of an ink tank 315, an ink pump 321, an ink filter F1, the head section 2 of the inkjet head 100, and an ink supply passage 311 and an ink discharge passage 331 connecting them. Furthermore, air valves V1 and V2 and air filters F2 and F3 are provided in the ink supply passage 311 and the ink discharge passage 331, respectively.

[0041] The upstream common liquid chamber 44 controls the ink circulation flow to a predetermined flow rate, while the downstream common liquid chamber 47 controls it to a predetermined pressure. For this reason, it is preferable that the downstream ink discharge passage 331 be wider than the ink supply passage 311. The ink supply passage 311 is, for example, a 3 mm diameter tube, and the ink discharge passage 331 is, for example, a 6 mm diameter tube. In this case, the opening of the upstream ink port 45 is 3 mm in diameter, and the opening of the downstream ink port 48 is 6 mm in diameter.

[0042] When the ink circulation device 341 is initially filled with ink, it first closes air valve V2 and opens air valve V1, supplying ink from the upstream side via ink pump 321. The ink flows into the head unit 2 via the upstream ink port 45 and flows through the upstream common liquid chamber 44. Then, it flows into the downstream common liquid chamber 47 via the pressure chambers 42 and bypass passages 49 of each channel. After that, air valve V1 is closed and air valve V2 is opened, and steady circulation occurs at a constant flow rate. At this time, the ink flowing in from the ink supply passage 311 is cleaner ink with fewer foreign matter compared to the ink in the ink discharge passage 331 because it has passed through filter F1. The ink in the ink discharge passage 331 is further from the ink pump 321 than the ink in the ink supply passage 311, and its pressure is stabilized in the ink tank 315, so it is less affected by the pulsation of the ink pump 321 and the pressure is stable. The settings for the ink flow rate through the upstream common liquid chamber 44, the ink flow rate through the pressure chamber 42 of each channel, and the ink flow rate through the bypass channel 49 are as previously described. The ink ejection operation of each channel is performed while maintaining this ink circulation flow.

[0043] Returning to the explanation in Figure 3, a piezoelectric actuator 5, which is an example of an actuator, is positioned on one side of the diaphragm 41 opposite to the pressure chamber 42. Each channel's piezoelectric actuator 5 is arranged in a position facing the pressure chamber 42, with the diaphragm 41 in between. The piezoelectric actuator 5 is positioned so that its central axis lies on the central axis of the pressure chamber 42. The piezoelectric actuator 5 and the diaphragm 41 are joined together, for example, with an adhesive. Each piezoelectric actuator 5 is fixed by joining one side opposite to the diaphragm 41 in the Z direction to a support member 7. In particular, as shown in Figure 3, the piezoelectric actuator 5 is a laminated piezoelectric actuator formed by alternately stacking piezoelectric elements 51, such as a piezo element, a first internal electrode 52, and a second internal electrode 53 in layers. Each piezoelectric element 51 is positioned with its polarization direction opposite to that of the others in the Z direction, for example, and is deformed in d33 mode. The first internal electrode 52 and the second internal electrode 53 are conductive films formed on the main surface of the piezoelectric element 51, respectively. The first internal electrodes 52 are formed to one end face of the piezoelectric actuator 5 in the Y direction and are connected to the first external electrodes 54 formed on this end face. The second internal electrodes 53 are formed to the other end face of the piezoelectric actuator 5 in the Y direction and are connected to the second external electrodes 55 formed on this end face.

[0044] The dummy layer 58 is made of the same material as the piezoelectric body 51. The dummy layer 58 does not have internal electrodes and is not subjected to an electric field, so it does not deform. The dummy layer 58 serves as a base for fixing the piezoelectric actuator 5 to the support member 7 (see Figure 4), or as a polishing surface for polishing during or after assembly to achieve accuracy. In particular, as shown in Figure 4, support columns 50 may be placed between the piezoelectric actuators 5 of each channel via grooves 59. The support columns 50 may be made of dummy actuators formed in the same way as the piezoelectric actuators 5 used for driving. The support columns 50 are positioned, for example, at the partition wall 40 between adjacent pressure chambers 42. The internal electrodes 52 and 53 of the support columns 50 are not connected to the drive circuit of the drive IC 3 described later, and are therefore not driven, so they do not deform. The support columns 50 may be made of a different material instead of being made of dummy actuators.

[0045] In the case of a piezoelectric actuator 5 in which multiple piezoelectric elements 51 are stacked, as an example, a first internal electrode 52 and a second internal electrode 53 are deposited on the main surface of each piezoelectric element 51 that has been processed into a thin plate shape. Then the piezoelectric elements 51 are stacked and fired to form a single unit. After that, a first external electrode 54 and a second external electrode 55 are deposited. After that, the piezoelectric elements 51 are polarized with a polarization voltage. The piezoelectric elements 51 are formed from lead-containing piezoelectric materials such as lead zirconate titanate (PZT) or lead-free piezoelectric materials such as sodium potassium niobate. The first internal electrode 52 and the second internal electrode 53 are deposited from a sinterable conductive material such as silver palladium. The first external electrode 54 and the second external electrode 55 are deposited from Ni, Cr, Au, etc., by known methods such as plating or sputtering.

[0046] The first external electrode 54 of each channel is connected to the individual wiring 56 of the flexible printed circuit board 21 (see Figure 3). The flexible printed circuit board 21 has a base material 26, individual wiring 56, an adhesive layer 27, and an insulating layer 28. The flexible printed circuit board 21 is arranged so that the area where the solder plating layer 29 is formed faces the first external electrode 54, and the first external electrode 54 of each channel and the individual wiring 56 are electrically and mechanically connected by melting solder. Instead of solder, the connections may be fixed with ACF (Anisotropic Conductive Film), ACP (Anisotropic Conductive Paste), NCF (Non-Conductive Film), NCP (Non-Conductive Paste), etc., and anisotropic conductive connection may be made in the thickness direction. On the other hand, the second external electrode 55 of each channel is connected to a common wiring (not shown) and, for example, to ground (GND) via the flexible printed circuit board 21.

[0047] Figure 8 shows an example of the drive circuit for the inkjet head 100. As shown in Figure 8, each channel (#1ch to #nch) piezoelectric actuator 5 has its first external electrode 54 connected to individual wiring 56, which is connected to the output terminal of the drive driver D (i.e., drive circuit) of the drive IC 3. The connection point between the first external electrode 54 and the individual wiring 56 is the individual terminal of the piezoelectric actuator 5. The second external electrode 55 is connected to common wiring 57 and connected to a common potential. The connection point between the second external electrode 55 and the common wiring 57 is the common terminal of the piezoelectric actuator 5.

[0048] The drive IC 3 is connected to power supplies 70 for drive voltage V1 and 71 for drive voltage V2, which are supplied to the piezoelectric actuator 5 when ejecting ink. Power supplies 70 and 71 have their positive terminals connected to the drive IC 3 and their negative terminals connected to ground (GND). The drive IC 3 is connected to the signal lines of the print data sent from the control board 17 (see Figure 1), which is the control unit of the inkjet printer 10. Print data is an example of a control signal. The common wiring 57 from the common terminal of the piezoelectric actuator 5 is connected to ground (GND).

[0049] Next, the ink ejection operation will be explained with reference to Figures 9 and 10. Each drive driver D of the drive IC3 uses drive voltages V1, V2 and ground (GND) to provide a drive waveform to the individual terminals of the piezoelectric actuator 5. Voltage V1 is, for example, 20V. Voltage V2 is, for example, 10V. Ground (GND) is, for example, 0V. Which channel of piezoelectric actuator 5 is driven is based, for example, on the print data. Figure 9 is an example of a drive waveform provided to the piezoelectric actuator 5.

[0050] When driving the piezoelectric actuator 5, which has a ground potential applied to its common terminal, a voltage V2 is applied to the individual terminals to put it into standby mode, as shown in Figure 9. When voltage V2 is applied, an electric field is applied in the direction of the polarization axis of the piezoelectric element 51, and due to the inverse piezoelectric effect of the piezoelectric element, the piezoelectric actuator 5 expands in the stacking direction (Z direction), as shown in Figure 10(a), and the volume of the pressure chamber 42 decreases. This is done prior to the ink ejection timing. Then, at the ink ejection timing (time t1 in Figure 9), the potential of the individual terminals is first lowered to ground (GND), so the expanded piezoelectric actuator 5 returns to its original position, i.e., contracts relatively, as shown in Figure 10(b), and the volume of the pressure chamber 42 expands relatively. When the volume of the pressure chamber 42 expands, the meniscus at the interface between the ink and the outside air in the nozzle 24 is pulled in a concave shape towards the pressure chamber 42.

[0051] For example, after half the pressure vibration period of the head unit 2 has elapsed, at time t2 in Figure 9, when a voltage V2 is applied to the individual terminals, as shown in Figure 10(c), the piezoelectric actuator 5 extends in the stacking direction (Z direction), relatively reducing the volume of the pressure chamber 42, causing ink droplets R to be ejected from the nozzle 24. Then, for example, after half the pressure vibration period of the head unit 2 has elapsed, at time t3 in Figure 9, a voltage V1 is applied to the individual terminals, and the voltage is returned to V2 at time t4 after a predetermined time. The extension (Figure 10(d)) and return (Figure 10(a)) of the piezoelectric actuator 5 at this time reduces and returns the volume of the pressure chamber 42, and this operation dampens residual vibrations. In this way, the volume of the pressure chamber 42 changes in accordance with the longitudinal vibration of the piezoelectric actuator 5 in the stacking direction, allowing ink to be ejected. When the series of ink ejections is complete, the volume of ink in the pressure chamber 42 has decreased by the amount ejected, so ink flows into the pressure chamber 42 via the upstream resistance flow path 43. At this time, if the ink flow rate supplied from the upstream side of the pressure chamber is low, ink is also drawn into the pressure chamber 42 from the downstream side via the downstream resistance channel 46. When ink flows into the common liquid chambers 44 and 47, the damper film of the upstream pressure damper 8 and the damper film of the downstream pressure damper 80 bend in a direction that reduces the volume of the damper chamber, thereby instantly supplying ink to the common liquid chambers 44 and 47. After that, the bent damper film returns to its original position as ink is replenished from the upstream ink port 45.

[0052] (Second Embodiment) Next, the inkjet head 100 of the second embodiment will be described. The inkjet head 100 of the second embodiment has the same configuration as the inkjet head 100 of the first embodiment, except that the arrangement of the pressure dampers 8, 80 and the bypass resistance channel 81 has been changed. That is, in the first embodiment, both the upstream pressure damper 8 and the downstream pressure damper 80 are placed in the bypass channel 49, but this is not the case.

[0053] In the second embodiment, the inkjet head 100 has a downstream pressure damper 80 located within the bypass channel 49, and an upstream pressure damper 8 located on the channel side connecting the upstream ink port 45 and the upstream common liquid chamber 44. As shown in Figure 11 as an example, the upstream pressure damper 8 has a damper chamber 83 extending in the Y direction, which communicates with the upstream ink port 45, and the opening in the Z direction is sealed with a soft material 82 which is a damper film. The downstream pressure damper 80 has a bypass resistance channel 81 located closer to the upstream common liquid chamber 44, so that most of the bypass channel 49 is a damper chamber, and the opening in the Z direction is sealed with a soft material 82 which is a damper film.

[0054] The upstream pressure damper 8 of the second embodiment is expected to have the effect of suppressing the pulsation of the ink pump 321. That is, when a circulation pump (ink pump 321) is located upstream of the ink supply path, the pulsation of the pump is more easily transmitted upstream than downstream, so it is desirable to configure the pressure damper to be located as close as possible to the upstream ink port 45. In this embodiment, the upstream pressure damper 8 is provided inside the head unit 2, but it can also be installed separately from the inkjet head 100, outside and upstream of the upstream ink port 45 (i.e., outside the inkjet head 100). Figure 12 shows an example of a separate upstream pressure damper 8. The upstream pressure damper 8 is located in the ink supply path 311. It is desirable to place it as close to the head unit 2 as possible. The upstream pressure damper 8 is configured as a damper chamber by providing a rectangular frame-shaped member with openings on one or both sides in the middle of the ink supply path 311, and sealing the opening with a soft material 82 which is a damper film. The separate inkjet head 100 and the upstream pressure damper 8 thus constitute a liquid ejection device.

[0055] (Third embodiment) Next, the inkjet head 100 of the third embodiment will be described. The inkjet head 100 of the third embodiment has the same configuration as the inkjet head 100 of the first embodiment, except that the arrangement of the pressure dampers 8, 80 and the bypass resistance flow path 81 has been changed.

[0056] In the third embodiment, the inkjet head 100 has an upstream pressure damper 8 located within the bypass channel 49, and a downstream pressure damper 80 located on the channel side connecting the downstream ink port 48 and the downstream common liquid chamber 47. As shown in Figure 13 as an example, the downstream pressure damper 80 has a damper chamber 84 extending in the Y direction, which communicates with the downstream ink port 48, and the opening in the Z direction is sealed with a soft material 82 which is a damper film. The upstream pressure damper 8 has a bypass resistance channel 81 located closer to the downstream common liquid chamber 47, so that most of the bypass channel 49 is a damper chamber, and the opening in the Z direction is sealed with a soft material 82 which is a damper film.

[0057] In other words, the inkjet head 100 of the third embodiment has a configuration in which the upstream and downstream are reversed compared to the inkjet head 100 of the second embodiment. This configuration is expected to have the effect of suppressing pump pulsation when the circulation pump (ink pump 321) is placed on the downstream side of the ink supply path. In this embodiment, the downstream pressure damper 80 is provided inside the head unit 2, but it can also be installed separately from the inkjet head 100 on the outside downstream of the downstream ink port 48 (i.e., outside the inkjet head 100). The downstream pressure damper 80 is placed in the ink discharge passage 331. It is preferable that the placement position is close to the head unit 2. Similar to the upstream pressure damper 8 shown in Figure 12, the downstream pressure damper 80 is configured as a damper chamber by providing, for example, a rectangular frame-shaped member with openings on one or both sides in the middle of the ink discharge passage 331, and the opening is sealed with a soft material 82 which is a damper film. The separate inkjet head 100 and the downstream pressure damper 80 constitute a liquid discharge device.

[0058] (Fourth Embodiment) Next, the inkjet head 100 of the fourth embodiment will be described. As shown in Figure 14, the inkjet head 100 of the fourth embodiment has a two-row arrangement of pressure chambers 42, and the upstream common liquid chamber 44 is shared between the rows. The upstream pressure damper 8 and the downstream pressure damper 80 are both placed in the bypass flow path 49, as in the first embodiment. However, the upstream pressure damper 8 is shared between the rows. With this configuration, a damping effect can be applied to both the upstream common liquid chamber 44 and the downstream common liquid chamber 47, as in the first embodiment. Furthermore, there is the advantage that a single flexible material 82 can be shared between the upstream pressure damper 8 and the downstream pressure damper 80.

[0059] (Fifth embodiment) Next, the inkjet head 100 of the fifth embodiment will be described. The inkjet head 100 of the fifth embodiment is a modification of the fourth embodiment in which the arrangement of pressure chambers 42 is configured in two rows. Similar to the second embodiment, the inkjet head 100 of the fifth embodiment has a downstream pressure damper 80 in the bypass flow path 49, and an upstream pressure damper 8 is provided on the flow path side that connects the upstream ink port 45 and the upstream common liquid chamber 44. As shown in Figure 15 as an example, the upstream pressure damper 8 has a damper chamber 83 formed at the connection between the upstream ink port 45 and the upstream common liquid chamber 44, and the opening in the Z direction is sealed with a soft material 82 which is a damper film. The downstream pressure damper 80 shared by each row has a bypass resistance flow path 81 positioned near the boundary with the upstream common liquid chamber 44, so that most of the bypass flow path 49 is a damper chamber, and the opening in the Z direction is sealed with a soft material 82 which is a damper film. This configuration, similar to the second embodiment, is expected to suppress pump pulsation when the circulation pump (ink pump 321) is placed upstream of the ink supply path. In this embodiment, the upstream pressure damper 8 is provided inside the head unit 2, but it can also be installed separately from the inkjet head 100, outside and upstream of the upstream ink port 45 (i.e., outside the inkjet head 100). The separate upstream pressure damper 8 can be placed, for example, in the ink supply path 311 (see Figure 12). The separate inkjet head 100 and the upstream pressure damper 8 constitute a liquid ejection device.

[0060] (Sixth Embodiment) Next, the inkjet head 100 of the sixth embodiment will be described. The inkjet head 100 of the sixth embodiment is a modification of the fourth embodiment in which the arrangement of pressure chambers 42 is configured in two rows. Similar to the third embodiment, the inkjet head 100 of the sixth embodiment has an upstream pressure damper 8 in the bypass flow path 49, and a downstream pressure damper 80 is provided on the flow path side that connects the downstream ink port 48 and the downstream common liquid chamber 47. In other words, the inkjet head 100 of the sixth embodiment has a configuration in which the upstream and downstream are reversed compared to the inkjet head 100 of the fifth embodiment. As shown in Figure 16 as an example, the downstream pressure damper 80 has a damper chamber 83 formed at the connection between the downstream common liquid chamber 47, which is shared between the rows, and the downstream ink port 48, and the opening in the Z direction is sealed with a soft material 82 which is a damper film. The upstream pressure damper 8 has a bypass resistance passage 81 positioned near the boundary with the downstream common liquid chamber 47, thereby making most of the bypass passage 49 a damper chamber, and sealing the opening in the Z direction with a soft material 82 which is a damper film. The upstream pressure damper 8 is shared between rows. This configuration, as in the third embodiment, is expected to have the effect of suppressing pump pulsation when the circulation pump (ink pump 321) is positioned downstream of the ink supply path. In this embodiment, the downstream pressure damper 80 is provided inside the head section 2, but it can also be installed separately from the inkjet head 100, outside downstream of the downstream ink port 48 (i.e., outside the inkjet head 100). The separate downstream pressure damper 80 is placed, for example, in the ink discharge passage 331. The separate inkjet head 100 and the downstream pressure damper 80 constitute a liquid discharge device.

[0061] (Seventh Embodiment) Next, the inkjet head 100 of the seventh embodiment will be described. The inkjet head 100 of the seventh embodiment is a modification of the first embodiment. That is, in the inkjet head 100 of the first embodiment, the other ends of the upstream common liquid chamber 44 and the downstream common liquid chamber 47 are connected by a bypass flow path 49, but this is not the only configuration. As shown in Figure 17, the inkjet head 100 of the seventh embodiment has the downstream ink port 48 positioned on one end of the bypass flow path 49, and is configured so that the bypass circulating flow passes only through the upstream common liquid chamber 44. The upstream pressure damper 8 has a damper chamber 83 that communicates with the upstream ink port 45 and extends in the Y direction, and the opening in the Z direction is sealed with a soft material 82 which is a damper film.

[0062] On the other hand, the pressure chamber circulating flow supplied from the upstream common liquid chamber 44 to each pressure chamber 42 via each upstream resistance flow path 43 merges in the downstream common liquid chamber 47, passes through the downstream flow path shown in Figure 17, and is discharged through the downstream ink port 48. The downstream pressure damper 80 has the portion of this downstream flow path designated as the downstream damper chamber 85, and its opening is sealed with a soft material 82 which is a damper film. In this way, even if the bypass flow and the downstream flow are separated into different paths, the same effects as in the above embodiment can be obtained if the relationship between the bypass resistance flow path 81 and the upstream / downstream pressure dampers 8 and 80 is the same. In this embodiment, the upstream pressure damper 8 is provided inside the head unit 2, but it can also be installed separately from the inkjet head 100, outside and upstream of the upstream ink port 45 (i.e., outside the inkjet head 100). The separate upstream pressure damper 8 can be placed, for example, in the ink supply path 311 (see Figure 12). The separate inkjet head 100 and upstream pressure damper 8 constitute the liquid ejection device.

[0063] As described above, according to the above embodiment, a bypass passage 49 is provided at the other end of the arrangement direction of the multiple pressure chambers 42, connecting the upstream common liquid chamber 44 and the downstream common liquid chamber 47. Furthermore, a bypass resistance passage 81 is provided in the bypass passage, and pressure dampers 8 and 80 are placed on the upstream and downstream sides of the bypass resistance passage 81. This makes it possible to stably eject ink in an ink circulation type head.

[0064] Providing the bypass channel 49 to increase the overall ink circulation flow rate of the print head 2 has the advantage of making it easier for the ink to transfer heat to the print head 2, bringing the temperature of the print head 2 closer to the temperature of the ink. In addition, providing the bypass channel 49 to increase the overall ink circulation flow rate of the print head 2 allows for agitation of the ink, which has the effect of preventing the settling of sedimentary inks, such as those containing silica.

[0065] As previously described, the upstream pressure damper 8 and the downstream pressure damper 80 may both be installed inside the head unit 2, or one of them may be installed separately outside the head unit 2. When both are installed inside the head unit 2, the response to sudden changes in ink ejection volume is faster than when they are installed outside the head unit 2, which is advantageous in that it stabilizes print quality immediately after a sudden change in print content. On the other hand, when either the upstream pressure damper 8 or the downstream pressure damper 80 is installed outside the head unit 2 and is separate from the inkjet head 100, it is easy to increase the size of the separate pressure dampers 8 and 80 even when the inkjet head 100 is miniaturized, which is advantageous in that it stabilizes print quality against large fluctuations in print content and ink supply pressure.

[0066] Furthermore, the piezoelectric actuator 5 is not limited to a laminated type in which multiple piezoelectric elements 51 are stacked. A piezoelectric actuator with a single layer of piezoelectric elements 51 may also be used. In addition, the operation of the actuator when a driving voltage is applied is not limited to longitudinal vibration. Moreover, it may be applied not only to the drop-on-demand piezoelectric method but also to the continuous method.

[0067] In the above-described embodiment, the inkjet head 100 of the inkjet printer 10 was described as an example of a liquid ejection device, but the liquid ejection device may also be the material ejection head of a 3D printer or the sample ejection head of a dispensing device.

[0068] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be carried out in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of Symbols]

[0069] 10 Inkjet Printers 100-103 Inkjet head 24 nozzles 42 Pressure chamber 43 Upstream resistance channel 44 Upstream common liquid chamber 45 Upstream ink port 46 Downstream resistance channel 47 Downstream common liquid chamber 48 Downstream Ink Port 49 Bypass channel 5. Piezoelectric actuator 8. Upstream pressure damper 80 Downstream pressure damper 81 Bypass resistor channel

Claims

1. Multiple pressure chambers, each connected to a nozzle, Multiple upstream resistance channels communicating with the aforementioned pressure chambers, An upstream common liquid chamber, one end of which communicates with the upstream liquid port and which communicates with the plurality of upstream resistance flow paths and extends in the direction of the arrangement of the plurality of pressure chambers, Multiple downstream resistance channels communicating with each of the aforementioned pressure chambers, A downstream common liquid chamber that communicates with the downstream liquid port and with the plurality of downstream resistance flow paths, and extends in the direction of the arrangement of the plurality of pressure chambers, A bypass channel connecting the other end of the upstream common liquid chamber and the downstream common liquid chamber, A bypass resistor channel is provided in the bypass channel, An upstream pressure damper is provided on the upstream side of the bypass resistance flow path, A liquid discharge head characterized by comprising a downstream pressure damper provided on the downstream side of the bypass resistance flow path.

2. The downstream pressure damper is provided within the bypass flow path. The liquid discharge head according to claim 1, characterized in that the upstream pressure damper is provided on the flow path side that connects the upstream liquid port and the upstream common liquid chamber.

3. The upstream pressure damper is provided within the bypass flow path. The liquid discharge head according to claim 1, characterized in that the downstream pressure damper is provided on the flow path side that connects the downstream liquid port and the downstream common liquid chamber.

4. The liquid discharge head according to any one of claims 1 to 3, characterized in that the total flow rate of the liquid flowing through the bypass channel and the liquid flowing through the plurality of channels from the inlet of each upstream resistance channel to the outlet of each downstream resistance channel is equal to or greater than the total maximum discharge flow rate of the liquid discharged from each nozzle.

5. Multiple pressure chambers, each connected to a nozzle, Multiple upstream resistance channels communicating with the aforementioned pressure chambers, An upstream common liquid chamber, one end of which communicates with the upstream liquid port and which communicates with the plurality of upstream resistance flow paths and extends in the direction of the arrangement of the plurality of pressure chambers, Multiple downstream resistance channels communicating with each of the aforementioned pressure chambers, A downstream common liquid chamber that communicates with the downstream liquid port and with the plurality of downstream resistance flow paths, and extends in the direction of the arrangement of the plurality of pressure chambers, A bypass channel connecting the other end of the upstream common liquid chamber and the downstream common liquid chamber, A bypass resistor channel is provided in the bypass channel, An upstream pressure damper is provided on the upstream side of the bypass resistance flow path, A liquid discharge device characterized by comprising a downstream pressure damper provided on the downstream side of the bypass resistance flow path.

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