Liquid dispensing head

Abstract

To provide a liquid discharge head that can suppress the pressure rise inside the head in a liquid circulation system. [Solution] The liquid discharge head of the embodiment comprises a flow path plate, a first common flow path, a second common flow path, and a bypass flow path. The flow path plate forms a plurality of pressure chambers each communicating with a nozzle that discharges liquid, a plurality of first resistance flow path sections each communicating with each pressure chamber, and a plurality of second resistance flow path sections each communicating with each pressure chamber. The first common flow path communicates with the plurality of first resistance flow path sections. The second common flow path communicates with the plurality of second resistance flow path sections. The bypass flow paths are arranged on both ends of the arrangement direction of the plurality of pressure chambers and connect the ends of the first common flow path and the second common flow path. The liquid discharge head circulates and supplies liquid to each pressure chamber via the first common flow path, the first resistance flow path section, the pressure chambers, the second resistance flow path section, and the second common flow path, and also circulates the liquid via the first common flow path, the bypass flow path, and the second common flow path to regulate the temperature of the flow path plate.

Description

Technical Field

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

Background Art

[0002] A liquid ejection head that supplies 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, or the like. 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 ejection channels for ejecting liquid. Each ejection 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 an ejection channel for ejecting liquid from among the plurality of ejection channels, and drives the actuator of the selected ejection channel to eject the liquid.

[0004] Some liquid ejection heads are provided with resistance channels at the connection portions between each pressure chamber and a common flow path. When a liquid ejection head having such a configuration is used in a liquid circulation type, the pressure inside the head may become significantly high when circulating a liquid at a predetermined flow rate.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem that this invention aims to solve is to provide a liquid discharge head that can suppress the pressure rise inside the head in a liquid circulation system. [Means for solving the problem]

[0007] The liquid discharge head according to an embodiment of the present invention comprises a flow path plate, a first common flow path, a second common flow path, and a bypass flow path. The flow path plate forms a plurality of pressure chambers each communicating with a nozzle for discharging liquid, a plurality of first resistance flow path sections each communicating with each of the pressure chambers, and a plurality of second resistance flow path sections each communicating with each of the pressure chambers. The first common flow path communicates with the plurality of first resistance flow path sections. The second common flow path communicates with the plurality of second resistance flow path sections. The bypass flow paths are arranged at both ends of the arrangement direction of the plurality of pressure chambers and connect the ends of the first common flow path and the second common flow path. The liquid discharge head circulates and supplies liquid to each of the pressure chambers via the first common flow path, the first resistance flow path section, the pressure chambers, the second resistance flow path section, and the second common flow path, and also circulates the liquid via the first common flow path, the bypass flow path, and the second common flow path to regulate the temperature of the flow path plate. [Brief explanation of the drawing]

[0008] [Figure 1] This is an overall configuration diagram of an inkjet printer equipped with an inkjet head according to an 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] This is a partially enlarged cross-sectional view of the head portion of the inkjet head shown above. [Figure 6] This is an overall configuration diagram of the ink circulation system for the inkjet head shown above. [Figure 7]This is a characteristic diagram showing the relationship between circulation flow rate and pressure when ink is circulated in the head section of an inkjet head that does not have a bypass channel. [Modes for carrying out the invention]

[0009] The liquid discharge head according to the embodiment will be described in detail below with reference to the attached drawings. In each drawing, identical components are denoted by the same reference numerals.

[0010] As an example of an image forming apparatus equipped with a liquid ejection head of the embodiment, an inkjet printer 10 for printing images on a recording medium will be described. Figure 1 shows a schematic configuration of the inkjet printer 10. The inkjet printer 10 has a cassette 12 for storing a sheet S, which is an example of a recording medium, an upstream transport path 13 for the sheet S, a transport belt 14 for transporting the sheet S taken out of the cassette 12, a plurality of inkjet heads 100-103 for ejecting ink droplets toward the sheet S on the transport belt 14, a downstream transport path 15 for the sheet S, an output tray 16, and a control board 17 arranged inside the housing 11. The operation unit 18, which is the user interface, is located on the upper side of the housing 11.

[0011] The image data to be printed on sheet S is generated, for example, by an externally connected device, such as a computer 200. The image data generated by the computer 200 is sent to the control board 17 of the inkjet printer 10 via cable 201 and connectors 202 and 203.

[0012] The pickup roller 204 supplies sheets S one by one from the cassette 12 to the upstream transport path 13. The upstream transport path 13 consists of feed roller pairs 131 and 132 and sheet guide plates 133 and 134. The sheets S are sent to the upper surface of the transport belt 14 via the upstream transport path 13. The arrow 104 in the figure indicates the transport path of the sheets S from the cassette 12 to the transport belt 14.

[0013] The conveyor belt 14 is a mesh-like endless belt with numerous through holes formed on its surface. Three rollers, a drive roller 141 and driven rollers 142 and 143, rotatably support the conveyor belt 14. A motor 205 rotates the conveyor belt 14 by rotating the drive roller 141. The motor 205 is an example of a drive device. In the figure, 105 indicates the direction of rotation of the conveyor belt 14. A negative pressure container 206 is placed on the back side of the conveyor belt 14. The negative pressure container 206 is connected to a pressure-reducing fan 207. The fan 207 creates negative pressure inside the negative pressure container 206 with the airflow it generates, causing the sheet S to adhere to and hold on the upper surface of the conveyor belt 14. In the figure, 106 indicates the flow of the airflow.

[0014] 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.

[0015] 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 6). In Figure 1, for ease of drawing, ink circulation devices 341-344 are shown with dashed lines.

[0016] 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.

[0017] Next, the configuration of the inkjet heads 100 to 103 will be described. The following describes the inkjet head 100 while referring to FIGS. 2 to 5, but the inkjet heads 101 to 103 also have the same structure as the inkjet head 100.

[0018] As shown in FIG. 2, the inkjet head 100 includes a head portion 2 which is an example of a liquid ejection portion. The head portion 2 is connected to a flexible printed wiring board 21. The flexible printed wiring board 21 is connected to a printed circuit board 22. The ink circulation type head portion 2 is connected to an ink circulation device 341 via an ink supply path 311 and an ink discharge path 331. The ink supply path 311 and the ink discharge path 331 are provided in a pair at both ends of the head portion 2 in the X direction.

[0019] The head portion 2 includes a nozzle plate 23. The nozzles 24 of each ejection channel for ejecting ink are arranged along, for example, the X direction in the first direction of the nozzle plate 23. The nozzle density is set, for example, within a range of 150 to 1200 dpi. The nozzles 24 are not limited to a single row and may be multiple rows. The detailed internal configuration of the head portion 2 will be described later.

[0020] The flexible printed wiring board 21 mounts a driving IC (Integrated Circuit) 3 (hereinafter referred to as a driving IC). The driving IC 3 as a control portion of the inkjet head 100 temporarily stores the print data sent from the control board 17 having a CPU as a control portion of the inkjet printer 10 via the printed circuit board 22, and gives a driving signal to each ejection channel so as to eject ink at a predetermined timing.

[0021] Figs. 3 to 5 are cross-sectional views of the head portion 2. The nozzle plate 23 is joined to one surface of the flow path plate 4. The nozzle plate 23 is a rectangular plate formed of a resin such as polyimide or a metal such as stainless steel, for example. The diaphragm 41 is joined to one surface of the flow path plate 4 on the side opposite to the nozzle plate 23. The diaphragm 41 has flexibility to deform when an external force is applied. The diaphragm 41 is a rectangular plate formed of a flexible polyimide film or metal, for example.

[0022] The flow path plate 4 has a structure in which, for example, two plates 411 and 412 each having openings or grooves formed therein are laminated in the Z direction. The pressure chambers 42 of each discharge channel are formed in the flow path plate 4 respectively. These plurality of pressure chambers 42 are arranged at the positions of the respective nozzles 24 and are in communication with the nozzles 24 respectively. As an example, the pressure chamber 42 is formed by forming a rectangular opening penetrating in the Z direction, for example, in the flow path plate 4 (411, 412), and closing the openings on both sides in the Z direction with the nozzle plate 23 and the diaphragm 41 respectively, thereby forming a space filled with ink. The pressure chamber 42 is formed in a groove shape along the Y direction, for example, in the third direction (see Fig. 5).

[0023] In the ink circulation type head, one end (upstream side) in the Y direction of each pressure chamber 42 communicates with the first common flow path 6 through the first resistance flow path portion 43, the ink introduction portion 44 formed in the flow path plate 4, and the ink supply port 45 formed in the diaphragm 41 respectively. The first common flow path 6 is formed, for example, in a frame 61 joined to one surface of the diaphragm 41. However, it is not limited to this and may be formed in the flow path plate 4. The first common flow path 6 is an ink supply manifold that is formed along the arrangement direction (X direction) of the pressure chambers 42 and communicates in common with each of the pressure chambers 42 of each discharge channel. The first ink port 62 for supplying ink to the first common flow path 6 is provided in a pair at both end sides in the arrangement direction of the plurality of pressure chambers 42, in the example of the figure, at both end sides in the X direction (see Fig. 5). Each first ink port 62 is connected to the ink supply path 311 respectively. The first ink port 62 is an example of the first liquid port.

[0024] The other end (downstream side) of each pressure chamber 42 in the Y direction is connected to a second common flow path 63 via a second resistance flow path section 46 and an ink discharge section 47 formed in the flow path plate 4, and an ink discharge port 48 formed in the diaphragm 41. The second common flow path 63 is formed, for example, within a frame 64 joined to one surface of the diaphragm 41. It is not limited to this, and may also be formed in the flow path plate 4. The second common flow path 63 is formed along the arrangement direction (X direction) of the pressure chambers 42, and is an ink discharge manifold that communicates in common with each of the pressure chambers 42 of each discharge channel. The second ink ports 65 that discharge ink from the second common flow path 63 to the head section 2 are provided in pairs on both ends in the arrangement direction of the multiple pressure chambers 42, in the example shown in the figure, on both ends in the X direction, similar to the first ink ports 62 (see Figure 5). Each second ink port 65 is connected to an ink discharge passage 331. The second ink port 65 is an example of a second liquid port.

[0025] The first resistance flow channel section 43 has a portion 431 in which the flow channel cross-section is reduced and flow resistance is provided by forming it, for example, narrower than the width of the pressure chamber 42 in the X direction, and a portion 432 in which the flow direction is changed, for example, from plate 411 to plate 412, and flow resistance is provided. Similarly, the second resistance flow channel section 46 has a portion 461 in which the flow channel cross-section is reduced and flow resistance is provided by forming it, for example, narrower than the width of the pressure chamber 42 in the X direction, and a portion 462 in which the flow direction is changed, for example, from plate 412 to plate 411, and flow resistance is provided.

[0026] The first resistance flow channel section 43 and the second resistance flow channel section 46 are preferably symmetrical in the Y direction via the pressure chamber 42, but are not limited to this. However, in order to suppress the occurrence of pressure differences between the discharge channels, they are formed so that the flow resistance ratio of the upstream and downstream sides of each discharge channel is the same. That is, the ratio of the flow resistance at the inlet of the first resistance flow channel section 43 to the flow resistance at the outlet of the second resistance flow channel section 46 when the ink is circulated is formed to be the same for each discharge channel. This flow resistance ratio of the upstream and downstream sides can also be adjusted by the size of the bypass flow channel 66, as will be described in more detail later.

[0027] The bypass channels 66 are provided in pairs on both ends of the arrangement direction of the multiple pressure chambers 42, in the example shown in the figure, on both ends in the X direction (see Figure 5). The bypass channels 66 are channels that bypass ink by connecting the other ends of the first common channel 6 and the second common channel 63. As an example, the bypass channels 66 are formed within a frame 67 joined to one surface of the diaphragm 41 (see Figure 3). However, they may also be formed in the channel plate 4. The bypass channels 66 are formed along the Y direction of the frame 67 and connect the first common channel 6 and the second common channel 63. The upstream inlet of the bypass channels 66 is located between the first ink port 62 and the first resistance channel section 43 of the nearest discharge channel from the first ink port 62 (see Figure 5). The downstream outlet of the bypass channels 66 is located between the second ink port 65 and the second resistance channel section 46 of the nearest discharge channel from the second ink port 65 (see Figure 5). As previously described, the flow resistance ratio between the upstream and downstream sides of each discharge channel can also be adjusted by the size of the bypass flow channel 66. That is, the size of the bypass flow channel 66 (flow channel length, area and shape of the flow channel cross-section, etc.) is set so that the flow resistance ratio between the inlet of the first resistance flow channel section 43 and the outlet of the second resistance flow channel section 46 is the same for each discharge channel.

[0028] As an example, the flow resistance of the bypass channel 66 is set to be less than half of the flow resistance from the inlet of the first resistance channel section 43 to the outlet of the second resistance channel section 46 of one ejection channel. Furthermore, the flow resistance of the bypass channel 66 is set to be smaller than the flow resistance of the first common channel 6. This preferably causes the ink flowing in from the first ink port 62 to flow in the bypass channel 66 and the first common channel 6 in an 8:2 ratio.

[0029] Figure 6 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. The ink circulation devices 342 to 344 that circulate and supply ink to the inkjet heads 101 to 103 have a similar configuration to the ink circulation device 341.

[0030] As shown in Figure 6, the ink circulation device 341 comprises an upstream ink tank 8, a downstream ink tank 81, an ink circulation pump 82, and an ink temperature controller 83. These are connected to each other by an ink flow path, such as a tube. The ink circulation pump 82 circulates the ink in the order of the upstream ink tank 8, the print head 2, and the downstream ink tank 81. The predetermined ink circulation flow rate is, for example, 15 ml / min. The ink temperature controller 83 regulates the ink temperature to a predetermined temperature. The ink temperature controller 83 is, for example, a heater. The predetermined temperature is selected from, for example, a range of 25 to 35°C. It is preferable to provide an ink filter F1 in the upstream ink flow path to prevent foreign matter from entering the print head 2. The ink filter F1 is, for example, a ball capsule filter. It is also preferable to place small containers 84 and 85, respectively, inside the upstream ink tank 8 and the downstream ink tank 81 as bubble traps. As previously described, since a pair of first ink ports 62 are provided, ink is supplied between the upstream ink tank 8 and the print head 2 via two ink supply passages 311. Similarly, since a pair of second ink ports 65 are provided, two ink discharge passages 331 are also provided between the print head 2 and the downstream ink tank 81.

[0031] The ink circulation device 341 further includes a negative pressure control device 9. The negative pressure control device 9 uses sensors to detect the internal pressure of the sealed upstream ink tank 8 and the downstream ink tank 81, and controls the pressure regulating pump 91 to adjust the circulation system to a predetermined negative pressure. The predetermined negative pressure is, for example, -1 kPa relative to atmospheric pressure. By creating a negative pressure in the circulation system, the negative pressure control device 9 prevents ink from leaking from the nozzle 24 when the system is not dispensing ink. As an example of pressure control, when the differential pressure between the upstream ink tank 8 and the downstream ink tank 81, detected by the sensors, deviates from a predetermined set value (for example, -1 kPa), the pressure regulating pump 91 is activated and its output is controlled. The pressure regulating pump 91 adjusts the pressure (negative pressure) in the downstream ink tank 81 by drawing ink towards the supply tank 92 via a three-way branch 93, returning it to the set value. The pressure regulating pump 91 is stopped during the period when the set value is maintained.

[0032] 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. The piezoelectric actuators 5 for each discharge channel are arranged in positions facing the pressure chamber 42, with the diaphragm 41 in between. The piezoelectric actuators 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 68. In particular, as shown in Figure 3, the piezoelectric actuator 5 is a laminated piezoelectric actuator formed by alternately stacking a piezoelectric body 51, such as a piezo element, a first internal electrode 52, and a second internal electrode 53 in layers. The first internal electrode 52 and the second internal electrode 53 are conductive films formed on the main surface of the piezoelectric body 51, respectively. The first internal electrode 52 is formed to one end face of the piezoelectric actuator 5 in the Y direction and is connected to a first external electrode 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.

[0033] The dummy layer 58 is made of the same material as the piezoelectric element 51. The dummy layer 58 does not have internal electrodes and does not deform because no electric field is applied to it. The dummy layer 58 serves as a base for fixing the piezoelectric actuator 5 to the support member 68 (see Figure 4), or as a polishing surface for polishing during or after assembly to achieve accuracy. In particular, as shown in Figure 4, a support column 50 may be placed between the piezoelectric actuators 5 of each discharge channel via a groove 59. The support column 50 may be made of a dummy actuator formed in the same way as the piezoelectric actuator 5 for driving. The support column 50 is placed, for example, at a position corresponding to the partition wall 40 between adjacent pressure chambers 42. The support column 50 may be made of a different material instead of being made of a dummy actuator.

[0034] The piezoelectric element 51 is formed from a lead-containing piezoelectric material such as lead zirconate titanate (PZT), or a lead-free piezoelectric material such as sodium potassium niobate. The first internal electrode 52 and the second internal electrode 53 are formed by depositing a sinterable conductive material such as silver palladium. The first external electrode 54 and the second external electrode 55 are formed by depositing Ni, Cr, Au, etc., using known methods such as plating or sputtering.

[0035] The first external electrode 54 of each piezoelectric actuator 5 is connected to the individual wiring of the flexible printed circuit board 21. On the other hand, the second external electrode 55 of each piezoelectric actuator 5 is connected to a common wiring (not shown) and, for example, to ground (GND) via the flexible printed circuit board 21. With the ground potential applied to the second external electrode 55 on the common terminal side, the drive IC 3 applies a drive voltage to the first external electrode 54 on the individual terminal side. This causes the piezoelectric actuator 5 to deform in the Z direction, bending the diaphragm 41 and changing the volume of the pressure chamber 42. The drive IC 3 combines multiple voltages (e.g., 20V, 10V, 0V) to form a drive waveform and controls the volume and pressure of the pressure chamber 42 to eject ink from the nozzle 24.

[0036] Next, an example of the operation of the inkjet head 100 with the above configuration will be described. For example, when the inkjet printer 10 is turned ON or wakes from sleep mode, the ink circulation pump 82 and ink temperature controller 83 are activated to circulate the ink and regulate its temperature to a predetermined level. The predetermined ink circulation flow rate is, for example, 15 ml / min. The predetermined temperature is selected from, for example, a range of 25 to 35°C.

[0037] On the other hand, the negative pressure control device 9 uses sensors to detect the internal pressure of the upstream ink tank 8 and the downstream ink tank 81, and controls the pressure adjustment pump 91 to achieve a predetermined negative pressure.

[0038] When ink circulation begins, the ink flowing in from the first ink port 62 within the print head 2 splits and flows into the bypass channel 66 and the first common channel 6. The flow rate ratio is, for example, 8:2. That is, ink is actively allowed to flow into the bypass channel 66, suppressing an increase in pressure within the print head 2. With the configuration shown in Figures 3 to 5, the ink circulation can regulate the temperature of the print head 2 (especially the flow path plate 4). Therefore, it is easier to regulate the temperature if the flow path plate 4 is made of a metal such as stainless steel. Temperature regulation of the flow path plate 4 consequently regulates the temperature of the pressure chamber 42.

[0039] Figure 7 is a characteristic diagram showing the relationship between circulation flow rate and pressure when ink is circulated to the head of the inkjet head before the bypass channel 66 is installed. As can be seen from Figure 7, as the circulation flow rate increases, the pressure on the upstream side rises significantly. At a predetermined circulation flow rate of 10 ml / min, the pressure on the upstream side reaches 15 kPa. Consequently, the load on the ink circulation pump 82 increases. In addition, in order to maintain a predetermined negative pressure of -1 kPa, the pressure on the downstream side must be reduced. Consequently, the load on the pressure regulating pump 91 increases.

[0040] In contrast, the inkjet head 100 equipped with a bypass channel 66 can suppress the pressure rise within the head unit 2, allowing for active ink circulation. As a result, more ink flows through the head unit 2, making it easier to maintain the pressure chamber 42 at a predetermined temperature. Ink temperature also affects ink ejection. That is, changes in ink temperature change the viscosity. Therefore, the circulation flow rate must be reduced, and if ink is ejected without being able to maintain the predetermined temperature, variations in the amount of ink ejected will occur, resulting in a decrease in print quality. The inkjet head 100 equipped with a bypass channel 66 can also suppress this decrease in print quality.

[0041] As described above, according to any of the embodiments described above, by providing a pair of bypass channels 66 that connect the first common channel 6 and the second common channel 63 at both ends in the arrangement direction of the multiple pressure chambers 42, it is possible to provide an inkjet head 100 that can suppress the pressure rise inside the head in a liquid circulation system.

[0042] 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.

[0043] 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.

[0044] 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]

[0045] 10 Inkjet Printers 100-103 Inkjet head 24 nozzles 4 Flow Plate 42 Pressure Chamber 43 First resistance channel section 46 Second Resistive Flow Channel 6. First Common Channel 5. Piezoelectric actuator 62 First Ink Port 63. Second Common Channel 65 Second Ink Port 66 Bypass channel

Claims

1. A flow path plate having a plurality of pressure chambers each communicating with a nozzle for discharging liquid, a plurality of first resistance flow path sections each communicating with each of the pressure chambers, and a plurality of second resistance flow path sections each communicating with each of the pressure chambers, A first common channel communicating with a plurality of the first resistance channel sections, A second common channel communicating with a plurality of the aforementioned second resistance channel sections, The system comprises bypass channels, each positioned at both ends in the direction of arrangement of the multiple pressure chambers, and connecting the ends of the first common channel and the second common channel. A liquid discharge head characterized by circulating and supplying liquid to each of the pressure chambers via the first common flow path, the first resistance flow path section, the pressure chamber, the second resistance flow path section, and the second common flow path, and circulating the liquid via the first common flow path, the bypass flow path, and the second common flow path to control the temperature of the pressure chamber.

2. The liquid discharge head according to claim 1, characterized in that the size of each bypass channel is such that the flow resistance ratio between the inlet of the first resistance channel and the outlet of the second resistance channel is the same among the multiple pressure chambers.

3. The liquid discharge head according to claim 1, characterized in that the circulation flow of the liquid is controlled by controlling the temperature of the flow path plate to control the temperature of the pressure chamber.

4. The liquid discharge head according to claim 1, characterized in that the inlets of the bypass passages, each located at both ends in the arrangement direction of the pressure chambers, are located between the first liquid ports, each located at both ends in the arrangement direction of the pressure chambers, and the first resistance passage section closest to the first liquid port.

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