Liquid discharge head, liquid discharge device and liquid supply method

Abstract

To suppress thickening of ink by evaporation of a liquid from a discharge port by flowing a liquid of a flow channel of a liquid discharge head, and reduce color irregularity of an image.SOLUTION: A liquid discharge head includes a discharge port for discharging a liquid, a flow channel where an energy generating element for generating energy used for discharging a liquid is arranged, a discharge port part for communicating between the discharge port and the flow channel, a supply flow channel for flowing a liquid from the outside into the flow channel, and an outflow flow channel for outflowing a liquid from the flow channel to the outside. When a height of the flow channel in a communication part between the flow channel and the discharge port part is represented by H μm, a length of the discharge port part in a direction where the liquid is discharged from the discharge port is represented by P μm, and a length of the discharge port part in a flow direction of the liquid in the flow channel is represented by W μm, H-0.34×P-0.66×W>1.7 is satisfied.SELECTED DRAWING: Figure 22

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head, a liquid ejection device, and a liquid supplying method, and more particularly to a liquid ejection head that performs an ejection operation while causing liquid to flow through a flow path between a liquid ejection port and an element that generates ejection energy. [Background technology]

[0002] As this type of liquid ejection head, Patent Document 1 describes a method of performing an ink ejection operation while circulating ink through a flow path between the ejection orifices of the liquid ejection head and a heating resistor that generates ejection energy by circulating ink through the liquid ejection head. With this configuration, the ink that has thickened due to the water content of the ink evaporating due to heat generated during the ejection operation can be discharged and new ink can be replenished, making it possible to prevent clogging of the ejection orifices due to thickening of the ink. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-355973 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a configuration in which liquid flows through a flow path between the ejection orifices and the energy generating elements as described in Patent Document 1, depending on the shape of the flow path and the ejection orifices, the quality of the liquid near the ejection orifices may vary even though the liquid is flowing. For example, in a liquid ejection head that ejects ink, the ink may thicken or the colorant concentration may change, resulting in poor ink ejection or uneven density of the recorded image.

[0005] The present invention is devised to solve the above-mentioned problems, and aims to provide a liquid ejection head, a liquid ejection device, and a liquid supply method that are capable of suppressing changes in the quality of the liquid near the ejection port in a configuration in which liquid is flowed through a flow path between the ejection port and an energy generating element. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a liquid ejection head comprising: an ejection port for ejecting liquid; a flow path in which an energy generating element that generates energy utilized to eject the liquid is disposed; an ejection port section that communicates the ejection port with the flow path; a supply flow path for causing liquid to flow into the flow path from the outside; and an outflow flow path for causing liquid to flow out from the flow path to the outside, wherein when the height of the flow path at the communication section between the flow path and the ejection port section is H μm, the length of the ejection port section in the direction in which the liquid is ejected from the ejection port is P μm, and the length of the ejection port section in the flow direction of the liquid in the flow path is W μm, H -0.34 ×P -0.66 ×W>1.7 The present invention is characterized in that: Effect of the Invention

[0007] According to the above configuration, it is possible to suppress changes in the quality of the liquid near the ejection openings by flowing the liquid through the flow path of the liquid ejection head, which in turn makes it possible to suppress thickening of the ink due to evaporation of the liquid from the ejection openings, and to reduce color unevenness in images. [Brief description of the drawings]

[0008] [Figure 1] 1 is a perspective view showing a schematic configuration of an inkjet recording apparatus according to an embodiment of a liquid ejection apparatus for ejecting liquid of the present invention. [Diagram 2] FIG. 2 is a schematic diagram showing a first circulation mode of a circulation path applied to a recording apparatus according to an embodiment. [Diagram 3] 11 is a schematic diagram showing a second circulation mode of the circulation path applied to the recording apparatus of the embodiment. FIG. [Figure 4] 1(a) to 1(f) are diagrams illustrating the difference in the amount of ink that flows into the liquid ejection head 3 in the first circulation mode and the second circulation mode. [Diagram 5] 1A and 1B are perspective views showing a liquid ejection head according to an embodiment. [Figure 6] FIG. 2 is an exploded perspective view showing each part or unit that constitutes the liquid ejection head. [Figure 7] 1(a) to 1(f) are views showing the front and back surfaces of the first, second and third flow path members. [Figure 8] FIG. 8 is a perspective view showing a part of FIG. 7(a) and showing an enlarged view of a flow path in a flow path member formed by joining first to third flow path members. [Figure 9] FIG. 9 is a cross-sectional view taken along line IX-IX in FIG. [Figure 10] 1(a) and 1(b) are a perspective view and an exploded perspective view showing one discharge module. [Figure 11] 1A, 1B and 1C are a plan view of a surface of a recording element substrate on which ejection ports are formed, a partially enlarged view thereof, and a plan view of the reverse side of the surface. [Figure 12] FIG. 12 is a perspective view showing a cross section taken along line XII-XII in FIG. [Figure 13] 11 is a partially enlarged plan view showing adjacent portions of recording element substrates in two adjacent ejection modules. FIG. [Figure 14] 13(a) and 13(b) are perspective views showing a liquid ejection head according to another example of the embodiment. [Figure 15] FIG. 11 is an exploded perspective view showing a liquid ejection head according to another example of the embodiment. [Figure 16] 13(a) to 13(e) are diagrams illustrating flow path members constituting a liquid ejection head according to another example of an embodiment. [Figure 17] 13 is a perspective view showing a liquid connection relationship between a recording element substrate and a flow path member in a liquid ejection head according to another example of an embodiment. FIG. [Figure 18]18 is a cross-sectional view taken along line XVIII-XVIII in FIG. 17. [Figure 19] 13A and 13B are a perspective view and an exploded view showing a discharge module in a liquid discharge head according to another example of the embodiment. [Figure 20] (a) is a schematic diagram showing the surface of the recording element substrate on which the ejection ports are arranged, (b) is the surface of the recording element substrate when the cover plate provided on the rear side of the recording element substrate is removed, and (c) is a schematic diagram showing the rear side of the surface on which the ejection ports are arranged. [Figure 21] FIG. 11 is a diagram illustrating a second application example of the inkjet recording apparatus according to the embodiment. [Figure 22] 1(a) to 1(c) are diagrams illustrating the structure of an ejection port and an ink flow path in the vicinity of the ejection port in a liquid ejection head according to a first embodiment of the present invention. [Figure 23] 7A to 7C are diagrams illustrating the state of an ink flow of ink flowing inside a liquid ejection head according to a second embodiment. [Figure 24] 13A and 13B are diagrams showing the state of the colorant concentration of the ink inside the ejection port portion according to the second embodiment and a comparative example. [Diagram 25] 13A and 13B are diagrams illustrating a comparison of the colorant concentrations of inks ejected from the liquid ejection heads of the second embodiment and the comparative example. [Figure 26] 11A and 11B are diagrams showing the relationship between a liquid ejection head that produces a flow mode according to the second embodiment and a liquid ejection head that produces a flow mode according to a comparative example. [Figure 27] 27(a) to 27(d) are diagrams illustrating the state of ink flow near the ejection port in the liquid ejection head in the regions above and below the threshold line shown in FIG. 26. [Figure 28] 1 is a diagram for explaining whether the flow is in flow mode A or flow mode B for liquid ejection heads of various shapes. FIG. [Figure 29] 13(a) to 13(c) are graphs showing the relationship between the number of shots (number of ejections) and the ejection speed at that time after a certain period of pause following ejection from a liquid ejection head in each flow mode. [Diagram 30]10A to 10C are diagrams illustrating the state of an ink flow that flows inside a liquid ejection head according to a third embodiment of the present invention. [Diagram 31] 10A to 10C are diagrams illustrating the state of an ink flow flowing inside a liquid ejection head according to a fourth embodiment of the present invention. [Diagram 32] 13A to 13C are diagrams illustrating the state of an ink flow that flows inside a liquid ejection head according to a fifth embodiment of the present invention. [Diagram 33] 13A to 13C are diagrams illustrating the state of an ink flow that flows inside a liquid ejection head according to a sixth embodiment of the present invention. [Diagram 34] 13A to 13C are diagrams illustrating the state of an ink flow that flows inside a liquid ejection head according to a seventh embodiment of the present invention. [Diagram 35] 13(a) and 13(b) are diagrams showing a liquid ejection head according to an eighth embodiment of the present invention, particularly showing the shape of the ejection ports. [Diagram 36] 13(a) and (b) are diagrams illustrating the state of ink flow in each flow mode inside a liquid ejection head according to a ninth embodiment of the present invention. [Figure 37] 13(a) and 13(b) are diagrams showing the state of the colorant concentration of ink inside the ejection port portion according to the ninth embodiment. [Figure 38] FIG. 23 is a diagram showing the relationship between the evaporation rate and the circulation flow rate for each flow mode in the ninth embodiment. [Figure 39] 13(a) to 13(c) are diagrams showing flow modes of three flow channel shapes according to a tenth embodiment of the present invention. [Diagram 40] FIG. 23 is a contour map showing flow mode judgment values ​​when the discharge port diameter is changed according to the tenth embodiment. [Diagram 41] 13(a) to 13(c) are diagrams showing the results of observing ejected droplets from ejection ports of different flow path shapes according to the tenth embodiment. [Diagram 42] FIG. 23 is a contour map showing the time it takes for an air bubble to communicate with the atmosphere when the discharge port diameter is changed according to the tenth embodiment. [Diagram 43]3A to 3C are diagrams illustrating the state of an ink flow of ink flowing inside the liquid ejection head according to the first embodiment. [Diagram 44] FIG. 13 is a diagram showing a liquid ejection head according to an eighth embodiment. [Diagram 45] FIG. 13 is a diagram showing a liquid ejection head according to an eighth embodiment. [Diagram 46] FIG. 1 is a diagram showing a recording device according to a first application example. [Figure 47] FIG. 13 is a diagram showing a third circulation mode. [Figure 48] 10A to 10C are diagrams illustrating modified examples of the liquid ejection head according to the first application example. [Figure 49] 10A to 10C are diagrams illustrating modified examples of the liquid ejection head according to the first application example. [Figure 50] 10A to 10C are diagrams illustrating modified examples of the liquid ejection head according to the first application example. [Figure 51] FIG. 13 is a diagram showing a recording device according to a third application example. [Figure 52] FIG. 13 is a diagram showing a fourth circulation mode. [Diagram 53] FIG. 13 is a diagram showing a liquid ejection head according to a third application example. [Figure 54] FIG. 13 is a diagram showing a liquid ejection head according to a third application example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, each application example and each embodiment to which the present invention can be applied will be described with reference to the drawings. The liquid ejection head of the present invention that ejects liquid such as ink and the liquid ejection device equipped with the liquid ejection head can be applied to devices such as printers, copiers, facsimiles with communication systems, and word processors with printer units. Furthermore, it can be applied to industrial recording devices combined with various processing devices. For example, it can be used for applications such as biochip production, electronic circuit printing, and semiconductor substrate production. In addition, each application example and each embodiment described below is an appropriate specific example of the present invention, and therefore various technically preferable limitations are attached. However, as long as it is in line with the idea of ​​the present invention, the present application example and embodiment are not limited to the application examples, embodiments, and other specific methods described in this specification.

[0010] (First application example) <Inkjet recording device> FIG. 1 is a diagram showing a schematic configuration of a liquid ejection device for ejecting liquid according to the present invention, particularly an inkjet recording device (hereinafter also referred to as a recording device) 1000 that ejects ink to perform recording. The recording device 1000 is a line-type recording device that includes a conveying section 1 for conveying a recording medium 2 and a line-type liquid ejection head 3 arranged approximately perpendicular to the conveying direction of the recording medium 2, and performs continuous recording in one pass while conveying multiple recording media 2 continuously or intermittently. Note that the recording medium 2 is not limited to cut paper, and may be a continuous roll medium. The liquid ejection head 3 includes a negative pressure control unit 230 for controlling the pressure (negative pressure) in the circulation path, a liquid supply unit 220 fluidly connected to the negative pressure control unit 230, a liquid connection section 111 that serves as an ink supply and discharge port for the liquid supply unit 220, and a housing 80. The liquid ejection head 3 of this embodiment includes ejection port rows for ejecting cyan C, magenta M, yellow Y, and black K inks, respectively, thereby enabling full-color recording. As described later in FIG. 2, the liquid ejection head 3 is fluidly connected to a liquid supply mechanism, which is a supply path that supplies liquid to the liquid ejection head 3, a main tank, and a buffer tank (see FIG. 2 described later). Four negative pressure control units 230 and liquid supply units 220 are provided corresponding to the four colors of ink. An electrical control unit that transmits power and ejection control signals to the liquid ejection head 3 is also electrically connected to the liquid ejection head 3. The liquid paths and electrical signal paths within the liquid ejection head 3 will be described later.

[0011] The recording device 1000 is an inkjet recording device in a configuration in which liquid such as ink is circulated between a tank and a liquid ejection head 3, which will be described later. The inkjet recording device of this application example is capable of applying various circulation configurations, such as the following first and second circulation configurations, as the circulation configuration (configuration). The first circulation configuration is a configuration in which two circulation pumps (for high pressure and low pressure) are operated downstream of the liquid ejection head 3 to circulate the liquid, and the second circulation configuration is a configuration in which two circulation pumps (for high pressure and low pressure) are operated upstream of the liquid ejection head 3 to circulate the liquid. The first and second circulation configurations will be described below.

[0012] <Explanation of the first circulation type> 2 is a schematic diagram showing a first circulation form of the circulation path applied to the recording device 1000 of this application example. The liquid ejection head 3 is fluidly connected to a first circulation pump (high pressure side) 1001, a first circulation pump (low pressure side) 1002, a buffer tank 1003, and the like. Note that in FIG. 2, for the sake of simplicity, only a path through which one color of ink flows out of cyan C, magenta M, yellow Y, and black K is shown, but in reality, circulation paths for all four colors are provided in the liquid ejection head 3 and the recording device main body.

[0013] In the first circulation mode, ink in the main tank 1006 is supplied to the buffer tank 1003 by the refill pump 1005, and then supplied to the liquid supply unit 220 of the liquid ejection head 3 via the liquid connection part 111 by the second circulation pump 1004. After that, the ink is adjusted to two different negative pressures (high pressure, low pressure) by the negative pressure control unit 230 connected to the liquid supply unit 220, and circulates by dividing into two flow paths, the high pressure side and the low pressure side. The ink in the liquid ejection head 3 circulates inside the head by the action of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 downstream of the liquid ejection head 3, and is discharged from the head 3 via the liquid connection part 111 and returned to the buffer tank 1003.

[0014] The buffer tank 1003, which is a sub-tank, is connected to the main tank 1006, has an air communication port (not shown) that communicates between the inside of the tank and the outside, and is capable of discharging air bubbles in the ink to the outside. A refill pump 1005 is provided between the buffer tank 1003 and the main tank 1006. The refill pump 1005 transfers ink consumed by discharging (discharging) ink from the discharge ports of the liquid discharge head 3 for recording by discharging ink, suction recovery, etc., from the main tank 1006 to the buffer tank 1003.

[0015] The two first circulation pumps 1001 and 1002 draw liquid from the liquid connection portion 111 of the liquid ejection head 3 and flow it to the buffer tank 1003. The first circulation pump is preferably a volumetric pump having a quantitative liquid delivery capacity. Specific examples include a tube pump, a gear pump, a diaphragm pump, a syringe pump, and the like, but a form in which a constant flow rate is ensured by arranging a general constant flow valve or a relief valve at the pump outlet, for example. When the liquid ejection head 3 is driven, the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 are operated to cause ink to flow at a predetermined flow rate in the common supply path 211 and the common recovery path 212, respectively. By flowing ink in this way, the temperature of the liquid ejection head 3 during recording is maintained at an optimal temperature. It is preferable that the predetermined flow rate when the liquid ejection head 3 is driven is set to a flow rate that can be maintained to a degree that the temperature difference between each recording element substrate 10 in the liquid ejection head 3 does not affect the recorded image quality. However, if the flow rate is set too high, the negative pressure difference between the recording element substrates 10 increases due to the influence of pressure loss in the flow path inside the liquid ejection unit 300, resulting in uneven density of the image. For this reason, it is preferable to set the flow rate while taking into consideration the temperature difference and negative pressure difference between the recording element substrates 10.

[0016] The negative pressure control unit 230 is provided in a path between the second circulation pump 1004 and the liquid ejection unit 300. This negative pressure control unit 230 operates to maintain the pressure downstream of the negative pressure control unit 230 (i.e., the liquid ejection unit 300 side) at a preset constant pressure even when the flow rate of ink in the circulation system fluctuates due to the difference in the ejection amount per unit area or the like. As the two pressure adjustment mechanisms of the high pressure side (H) and the low pressure side (L) constituting the negative pressure control unit 230, any mechanism may be used as long as it can control the pressure downstream of the negative pressure control unit 230 to fluctuate within a certain range centered on a desired set pressure. As an example, a mechanism similar to a so-called "pressure reducing regulator" can be adopted. In the circulation flow path in this application example, the upstream side of the negative pressure control unit 230 is pressurized by the second circulation pump 1004 via the liquid supply unit 220. By doing so, the effect of the head pressure of the buffer tank 1003 on the liquid ejection head 3 can be suppressed, so that the degree of freedom in the layout of the buffer tank 1003 in the recording apparatus 1000 can be increased.

[0017] The second circulation pump 1004 may be any pump having a head pressure equal to or greater than a certain pressure within the range of the ink circulation flow rate used when driving the liquid ejection head 3, and may be a turbo pump, a positive displacement pump, or the like. Specifically, a diaphragm pump or the like may be used. Also, instead of the second circulation pump 1004, for example, a head tank disposed with a certain head difference relative to the negative pressure control unit 230 may be used.

[0018] As shown in Fig. 2, the negative pressure control unit 230 includes two pressure adjustment mechanisms H and L, each of which is set to a different control pressure. Of the two negative pressure adjustment mechanisms, the relatively high pressure setting side (indicated as H in Fig. 2) and the relatively low pressure setting side (indicated as L in Fig. 2) are connected to a common supply path 211 and a common recovery flow path 212 in the liquid ejection unit 300, respectively, via the liquid supply unit 220. The liquid ejection unit 300 is provided with the common supply path 211, the common recovery flow path 212, and individual flow paths 215 (individual supply flow paths 213, individual recovery flow paths 214) that communicate with each recording element substrate. The pressure adjustment mechanism H is connected to the common supply flow path 211, and the pressure adjustment mechanism L is connected to the common recovery flow path 212, respectively, to generate a pressure difference between the two common flow paths. Since the individual flow paths 215 are connected to the common supply path 211 and the common recovery path 212, a flow (arrow in FIG. 2) occurs in which a portion of the liquid flows from the common supply path 211 through the internal path of the recording element substrate 10 to the common recovery path 212. The two negative pressure adjustment mechanisms H, L are each connected to a path from the liquid connection part 111 via a filter 221.

[0019] In this way, in the liquid ejection unit 300, a flow occurs in which liquid flows through the common supply flow path 211 and the common recovery flow path 212, while a part of the liquid passes through each recording element substrate 10. Therefore, heat generated in each recording element substrate 10 can be discharged to the outside of the recording element substrate 10 by the ink flowing through the common supply flow path 211 and the common recovery flow path 212. In addition, with this configuration, when recording is performed by the liquid ejection head 3, a flow of ink can be generated even in the ejection ports and pressure chambers that are not ejecting. This reduces the viscosity of the ink that has thickened in the ejection ports, thereby suppressing the increase in viscosity of the ink. In addition, the thickened ink and foreign matter in the ink can be discharged to the common recovery flow path 212. Therefore, the liquid ejection head 3 of this application example is capable of high-speed, high-quality recording.

[0020] <Explanation of the second circulation type> 3 is a schematic diagram showing a second circulation form, which is a circulation form different from the first circulation form described above, among the circulation paths applied to the recording apparatus of this application example. The main difference from the first circulation form described above is that both of the two pressure adjustment mechanisms constituting the negative pressure control unit 230 control the pressure upstream of the negative pressure control unit 230 to fluctuate within a certain range centered on a desired set pressure. Another difference from the first circulation form is that the second circulation pump 1004 acts as a negative pressure source that reduces the pressure downstream of the negative pressure control unit 230. Another difference is that the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 are arranged upstream of the liquid ejection head 3, and the negative pressure control unit 230 is arranged downstream of the liquid ejection head 3.

[0021] In the second circulation mode, as shown in FIG. 3, the ink in the main tank 1006 is supplied to the buffer tank 1003 by the refill pump 1005. The ink is then divided into two flow paths, and circulated through two flow paths, a high-pressure side and a low-pressure side, by the action of the negative pressure control unit 230 provided in the liquid ejection head 3. The ink divided into the two flow paths, the high-pressure side and the low-pressure side, is supplied to the liquid ejection head 3 through the liquid connection part 111 of the liquid ejection head 3 by the action of the first circulation pump (high-pressure side) 1001 and the first circulation pump (low-pressure side) 1002. The ink circulated in the liquid ejection unit 300 by the action of the first circulation pump (high-pressure side) 1001 and the first circulation pump (low-pressure side) 1002 is then discharged from the liquid ejection head 3 through the liquid connection part 111 via the negative pressure control unit 230. The discharged ink is returned to the buffer tank 1003 by the second circulation pump 1004.

[0022] The negative pressure control unit 230 in the second circulation form acts to stabilize the pressure fluctuation on the upstream side of the negative pressure control unit 230 (i.e., the liquid ejection unit 300 side) within a certain range centered on a preset pressure even if there is a fluctuation in the flow rate caused by a change in the ejection amount per unit area. In the circulation flow path of this application example, the second circulation pump 1004 pressurizes the downstream side of the negative pressure control unit 230 via the liquid supply unit 220. In this way, the influence of the head pressure of the buffer tank 1003 on the liquid ejection head 3 can be suppressed, so that the range of options for the layout of the buffer tank 1003 in the recording device 1000 can be expanded. Instead of the second circulation pump 1004, for example, a head tank arranged with a predetermined head difference with respect to the negative pressure control unit 230 can also be applied. In the second circulation form, similar to the first circulation form described above, the negative pressure control unit 230 is provided with two pressure adjustment mechanisms H and L, each of which is set with a different control pressure. Of the two negative pressure adjustment mechanisms H and L, the high pressure setting side (indicated as H in FIG. 3) and the low pressure setting side (indicated as L in FIG. 3) are respectively connected to the common supply path 211 and the common recovery flow path 212 in the liquid ejection unit 300 via the liquid supply unit 220. By making the pressure of the common supply flow path 211 relatively higher than the pressure of the common recovery flow path 212 by the two negative pressure adjustment mechanisms, an ink flow is generated that flows from the common supply flow path 211 to the common recovery flow path 212 via the individual flow paths 213 and the internal flow paths of each recording element substrate 10.

[0023] In such a second circulation mode, an ink flow state similar to that in the first circulation mode is obtained in the liquid ejection unit 300, but there are two advantages different from the first circulation mode. The first is that in the second circulation mode, since the negative pressure control unit 230 is disposed downstream of the liquid ejection head 3, there is less concern that dust or foreign matter generated from the negative pressure control unit 230 will flow into the liquid ejection head 3. The second is that in the second circulation mode, the maximum flow rate required to supply liquid from the buffer tank 1003 to the liquid ejection head 3 can be smaller than in the first circulation mode. The reasons for this are as follows.

[0024] The sum of the flow rates in the common supply flow path 211 and the common recovery flow path 212 when circulating during standby for recording is defined as flow rate A. The value of flow rate A is defined as the minimum flow rate required to keep the temperature difference in the liquid ejection unit 300 within a desired range, for example, when adjusting the temperature of the liquid ejection head 3 during standby for recording. In addition, the ejection flow rate when ink is ejected from all the ejection ports of the liquid ejection unit 300 (during full ejection) is defined as flow rate F (ejection amount per ejection port × ejection frequency per unit time × number of ejection ports).

[0025] Fig. 4 is a diagram illustrating the difference in the amount of ink flowing into the liquid ejection head 3 in the first circulation mode and the second circulation mode. Fig. 4(a) shows the first circulation mode during standby, and Fig. 4(b) shows the first circulation mode during full ejection. Fig. 4(c) to Fig. 4(f) show the flow rates in the case of the second circulation flow path, with Fig. 4(c) and (d) showing the case where flow rate F<flow rate A, and Fig. 4(e) and (f) showing the case where flow rate F>flow rate A, and showing the flow rates during standby and full ejection, respectively.

[0026] The first circulation configuration (FIGS. 4(a) and 4(b)) will be described in which the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002, each having a quantitative liquid delivery capacity, are disposed downstream of the liquid ejection head 3. In this case, the total set flow rate of the first circulation pump 1001 and the first circulation pump 1002 is flow rate A (FIG. 4(a)). This flow rate A enables temperature control within the liquid ejection unit 300 during standby. When full ejection is performed by the liquid ejection head 3, the total set flow rate of the first circulation pump 1001 and the first circulation pump 1002 remains at flow rate A, but negative pressure caused by ejection by the liquid ejection head 3 acts. As a result, the maximum flow rate supplied to the liquid ejection head 3 is the total set flow rate A plus the consumption (flow rate F) due to full ejection. Therefore, the maximum value of the supply amount to the liquid ejection head 3 is flow rate A+flow rate F, since flow rate F is added to flow rate A (FIG. 4(b)).

[0027] On the other hand, in the case of the second circulation mode in which the first circulation pump 1001 and the first circulation pump 1002 are disposed on the upstream side of the liquid ejection head 3 (FIGS. 4(c) to (f)), the supply amount to the liquid ejection head 3 required during recording standby is the flow rate A, as in the first circulation mode. Therefore, in the second circulation mode in which the first circulation pump 1001 and the first circulation pump 1002 are disposed on the upstream side of the liquid ejection head 3, when the flow rate A is greater than the flow rate F (FIGS. 4(c) and (d)), the supply amount to the liquid ejection head 3 is sufficient even during full ejection. In that case, the discharge flow rate from the liquid ejection head 3 is the flow rate A minus the flow rate F (FIG. 4(d)). However, when the flow rate F is greater than the flow rate A (FIGS. 4(e) and (f)), if the supply flow rate to the liquid ejection head 3 is set to the flow rate A during full ejection, the flow rate will be insufficient. Therefore, when the flow rate F is greater than the flow rate A, the supply amount to the liquid ejection head 3 needs to be set to the flow rate F. At that time, when full ejection is performed, the flow rate F is consumed in the liquid ejection head 3, so the discharge flow rate from the liquid ejection head 3 is almost zero (FIG. 4(f)). Note that when the flow rate F is greater than the flow rate A and ejection is performed but not full ejection, the amount discharged from the liquid ejection head 3 is the flow rate F minus the amount consumed in ejection.

[0028] Thus, in the case of the second circulation mode, the sum of the set flow rates of the first circulation pump 1001 and the first circulation pump 1002, i.e., the maximum required supply flow rate, is the larger of the flow rate A and the flow rate F. For this reason, as long as the liquid discharge unit 300 of the same configuration is used, the maximum required supply flow rate in the second circulation mode (flow rate A or flow rate F) will be smaller than the maximum required supply flow rate in the first circulation mode (flow rate A+flow rate F).

[0029] Therefore, in the case of the second circulation mode, the degree of freedom of the applicable circulation pump is increased, and for example, a low-cost circulation pump with a simple configuration can be used, and the load on the cooler (not shown) installed in the main body side path can be reduced, which has the advantage of reducing the cost of the recording device. This advantage becomes greater as the line head has a relatively large value of the flow rate A or the flow rate F, and is more beneficial for line heads with a longer longitudinal length.

[0030] However, on the other hand, the first circulation mode has an advantage over the second circulation mode in some respects. That is, in the second circulation mode, the flow rate flowing through the liquid ejection unit 300 during recording standby is the maximum, so that the image with a smaller ejection amount per unit area (hereinafter also referred to as a low-duty image) is in a state in which a higher negative pressure is applied to each ejection port. For this reason, when the flow path width is narrow and the negative pressure is high, a high negative pressure is applied to the ejection port in a low-duty image in which unevenness is easily visible, so that there is a risk of a decrease in recording quality. On the other hand, in the case of the first circulation mode, a high negative pressure is applied to the ejection port when an image with a large ejection amount per unit area (hereinafter also referred to as a high-duty image) is formed, so that even if satellite droplets are generated, they are difficult to see, and there is an advantage that the impact on the image is small. The selection of these two circulation modes can be made in light of the specifications (ejection flow rate F, minimum circulation flow rate A, and flow path resistance in the head) of the liquid ejection head and the recording device main body.

[0031] <Explanation of the third circulation type> 47 is a schematic diagram showing a third circulation path which is one form of the circulation path applied to the recording device of this application example. Descriptions of functions and configurations similar to those of the first and second circulation paths will be omitted, and differences will be mainly described.

[0032] In this circulation path, liquid is supplied into the liquid ejection head 3 from two locations in the center of the liquid ejection head 3 and one end side of the liquid ejection head 3, a total of three locations. The liquid is collected into the common recovery flow path 212 after passing through each pressure chamber 23 from the common supply flow path 211, and is collected to the outside from a recovery opening at the other end of the liquid ejection head 3. The individual flow paths 213 communicate with the common supply path 211 and the common recovery flow path 212, and the recording element substrate 10 and the pressure chambers 23 disposed in the recording element substrate are provided in the path of each individual flow path 213. Therefore, a part of the liquid flowed by the first circulation pump 1002 passes through the pressure chambers 23 of the recording element substrate 10 from the common supply flow path 211 and flows into the common recovery flow path 212 (arrow in FIG. 47). This is because a pressure difference is provided between the pressure adjustment mechanism H connected to the common supply flow path 211 and the pressure adjustment mechanism L connected to the common recovery flow path 212, and the first circulation pump 1002 is connected only to the common recovery flow path 212.

[0033] In this way, in the liquid ejection unit 300, a flow of liquid that passes through the common recovery channel 212 and a flow that passes from the common supply channel 211 through the pressure chambers 23 in each recording element substrate 10 to the common recovery channel 212 are generated. Therefore, while suppressing an increase in pressure loss, heat generated in each recording element substrate 10 can be discharged to the outside of the recording element substrate 10 by the flow from the common supply channel 211 to the common recovery channel 212. Furthermore, according to this circulation path, it is possible to reduce the number of pumps, which are liquid transport means, compared to the first and second circulation paths.

[0034] <Description of Liquid Ejection Head Configuration> The configuration of the liquid ejection head 3 according to the first application example will be described. FIGS. 5(a) and (b) are perspective views showing the liquid ejection head 3 according to this application example. The liquid ejection head 3 is a line-type (page-wide type) liquid ejection head in which 15 recording element substrates 10 capable of ejecting four colors of ink, cyan C / magenta M / yellow Y / black K, are arranged in a straight line (arranged in-line). As shown in FIG. 5(a), the liquid ejection head 3 includes a signal input terminal 91 and a power supply terminal 92 electrically connected to each recording element substrate 10 via a flexible wiring substrate 40 and an electric wiring substrate 90. The signal input terminal 91 and the power supply terminal 92 are electrically connected to a control unit of the recording device 1000, and supply an ejection drive signal and power required for ejection to the recording element substrate 10, respectively. By consolidating the wiring by an electric circuit in the electric wiring substrate 90, the number of signal output terminals 91 and power supply terminals 92 can be reduced compared to the number of recording element substrates 10. This reduces the number of electrical connections that need to be removed when assembling the liquid ejection head 3 to the recording apparatus 1000 or when replacing the liquid ejection head. As shown in FIG. 5(b), the liquid connections 111 provided at both ends of the liquid ejection head 3 are connected to the liquid supply system of the recording apparatus 1000 described above with reference to FIGS. 2 and 3. This allows four colors of ink, cyan C / magenta M / yellow Y / black K, to be supplied from the supply system of the recording apparatus 1000 to the liquid ejection head 3, and the ink that has passed through the liquid ejection head 3 is collected by the supply system of the recording apparatus 1000. In this way, the inks of each color can circulate through the paths of the recording apparatus 1000 and the paths of the liquid ejection head 3.

[0035] FIG. 6 is an exploded perspective view showing each part or unit constituting the liquid ejection head 3. The liquid ejection unit 300, the liquid supply unit 220, and the electric wiring board 90 are attached to the housing 80. The liquid supply unit 220 is provided with the liquid connection part 111 (see FIG. 3), and the liquid supply unit 220 is provided with filters 221 (see FIG. 2 and FIG. 3) for each color that communicate with the openings of the liquid connection part 111 to remove foreign matter from the ink being supplied. The two liquid supply units 220 are each provided with filters 221 for two colors. The liquid that has passed through the filters 221 is supplied to the negative pressure control units 230 arranged on the liquid supply unit 220 corresponding to each color. The negative pressure control units 230 are units consisting of pressure adjustment valves for each color, and the valves and spring members arranged therein greatly attenuate the pressure loss change in the supply system of the recording device 1000 (the supply system upstream of the liquid ejection head 3) that occurs with the fluctuation in the flow rate of the liquid. This enables the negative pressure control unit 230 to stabilize the negative pressure change downstream of the pressure control unit (on the liquid discharge unit 300 side) within a certain range. Two pressure adjustment valves for each color are built into the negative pressure control unit 230 for each color, as described in Fig. 2. The two pressure adjustment valves are set to different control pressures, and the high-pressure side communicates with the common supply flow path 211 (see Fig. 2) in the liquid discharge unit 300, and the low-pressure side communicates with the common recovery flow path 212 (see Fig. 2) via the liquid supply unit 220.

[0036] The housing 80 is composed of a liquid discharge unit support part 81 and an electric wiring board support part 82, and supports the liquid discharge unit 300 and the electric wiring board 90 while ensuring the rigidity of the liquid discharge head 3. The electric wiring board support part 82 is for supporting the electric wiring board 90, and is fixed to the liquid discharge unit support part 81 by screwing. The liquid discharge unit support part 81 has a role of correcting warping and deformation of the liquid discharge unit 300 and ensuring the relative positional accuracy of the multiple recording element boards 10, thereby suppressing streaks and unevenness in the recorded matter. For this reason, the liquid discharge unit support part 81 preferably has sufficient rigidity, and is preferably made of a metal material such as SUS or aluminum, or a ceramic such as alumina. The liquid discharge unit support part 81 is provided with openings 83 and 84 into which the joint rubber 100 is inserted. The liquid supplied from the liquid supply unit 220 is led to the third flow path member 70 constituting the liquid discharge unit 300 via the joint rubber.

[0037] The liquid ejection unit 300 is composed of a plurality of ejection modules 200 and a flow path member 210, and a cover member 130 is attached to the recording medium side surface of the liquid ejection unit 300. Here, the cover member 130 is a member having a frame-shaped surface with a long opening 131 as shown in FIG. 6, and the recording element substrate 10 and the sealant part 110 (see FIG. 10 described later) included in the ejection module 200 are exposed from the opening 131. The frame part around the opening 131 functions as a contact surface of a capping member that caps the liquid ejection head 3 during standby for recording. For this reason, it is preferable to apply an adhesive, sealant, filler, or the like along the periphery of the opening 131 to fill unevenness and gaps on the ejection port surface of the liquid ejection unit 300, so that a closed space is formed when capping.

[0038] Next, the configuration of the flow path member 210 included in the liquid discharge unit 300 will be described. As shown in Fig. 6, the flow path member 210 is a laminate of a first flow path member 50, a second flow path member 60, and a third flow path member 70, and distributes the liquid supplied from the liquid supply unit 220 to each discharge module 200. The flow path member 210 is also a flow path member for returning the liquid circulating from the discharge module 200 to the liquid supply unit 220. The flow path member 210 is fixed to the liquid discharge unit support part 81 by screws, which suppresses warping and deformation of the flow path member 210.

[0039] 7(a) to 7(f) are diagrams showing the front and back surfaces of each of the first to third flow path members. Fig. 7(a) shows the surface of the first flow path member 50 on which the discharge module 200 is mounted, and Fig. 7(f) shows the surface of the third flow path member 70 that abuts against the liquid discharge unit support part 81. The first flow path member 50 and the second flow path member 60 are joined so that the abutting surfaces of the respective flow path members shown in Figs. 7(b) and 7(c) face each other, and the second flow path member and the third flow path member are joined so that the abutting surfaces of the respective flow path members shown in Figs. 7(d) and 7(e) face each other. By joining the second flow path member 60 and the third flow path member 70, eight common flow paths (211a, 211b, 211c, 211d, 212a, 212b, 212c, 212d) extending in the longitudinal direction of the flow path member are formed from the common flow path grooves 62 and 71 formed in each flow path member. As a result, a set of a common supply flow path 211 and a common recovery flow path 212 is formed for each color in the flow path member 210. Ink is supplied from the common supply flow path 211 to the liquid ejection head 3, and the ink supplied to the liquid ejection head 3 is recovered by the common recovery flow path 212. The communication port 72 (see FIG. 7(f)) of the third flow path member 70 communicates with each hole of the joint rubber 100, and is in fluid communication with the liquid supply unit 220 (see FIG. 6). A plurality of communication ports 61 (communication port 61-1 communicating with the common supply flow path 211, and communication port 61-2 communicating with the common recovery flow path 212) are formed on the bottom surface of the common flow path groove 62 of the second flow path member 60, and communicate with one end of the individual flow path groove 52 of the first flow path member 50. A communication port 51 is formed on the other end of the individual flow path groove 52 of the first flow path member 50, and the individual flow path groove 52 is fluidly connected to the plurality of discharge modules 200 via the communication port 51. The individual flow path groove 52 makes it possible to aggregate the flow paths toward the center side of the flow path member.

[0040] The first to third flow path members are preferably made of a material that is resistant to corrosion by liquids and has a low linear expansion coefficient. Suitable materials include alumina, LCP (liquid crystal polymer), PPS (polyphenyl sulfide), PSF (polysulfone), and modified PPE (polyphenylene ether) as a base material, and a composite material (resin material) with inorganic fillers such as silica particles and fibers added thereto. The flow path member 210 may be formed by laminating three flow path members and bonding them together, or, when a resin composite resin material is selected as the material, a joining method by welding may be used.

[0041] Fig. 8 shows the α portion of Fig. 7(a), and is a partially enlarged perspective view of the flow paths in a flow path member 210 formed by joining the first to third flow path members, viewed from the surface of the first flow path member 50 on which the discharge module 200 is mounted. The common supply flow path 211 and the common recovery flow path 212 are alternately arranged from the flow paths at both ends. Here, the connection relationship of the respective flow paths in the flow path member 210 will be described.

[0042] The flow path member 210 is provided with common supply flow paths 211 (211a, 211b, 211c, 211d) and common recovery flow paths 212 (212a, 212b, 212c, 212d) that extend in the longitudinal direction of the liquid ejection head 3 for each color. A plurality of individual supply flow paths (213a, 213b, 213c, 213d) formed by the individual flow path grooves 52 are connected to the common supply flow paths 211 for each color via the communication ports 61. In addition, a plurality of individual recovery flow paths (214a, 214b, 214c, 214d) formed by the individual flow path grooves 52 are connected to the common recovery flow paths 212 for each color via the communication ports 61. With this flow path configuration, ink can be collected from each common supply flow path 211 via the individual supply flow paths 213 to the recording element substrate 10 located at the center of the flow path member. Furthermore, ink can be recovered from the recording element substrate 10 to each common recovery passage 212 via the individual recovery passages 214 .

[0043] 9 is a diagram showing a cross section taken along line IX-IX in FIG. 8. Each of the individual recovery flow paths (214a, 214c) communicates with the ejection module 200 via a communication port 51. Although only the individual recovery flow paths (214a, 214c) are shown in FIG. 9, in another cross section, the individual supply flow paths 213 communicate with the ejection module 200 as shown in FIG. 8. A flow path is formed in the support member 30 and the recording element substrate 10 included in each ejection module 200 to supply ink from the first flow path member 50 to the recording element 15 provided on the recording element substrate 10. Furthermore, a flow path is formed in the support member 30 and the recording element substrate 10 to recover (circulate) a part or all of the liquid supplied to the recording element 15 to the first flow path member 50.

[0044] Here, the common supply flow path 211 of each color is connected to the negative pressure control unit 230 (high pressure side) of the corresponding color via the liquid supply unit 220, and the common recovery flow path 212 is connected to the negative pressure control unit 230 (low pressure side) via the liquid supply unit 220. This negative pressure control unit 230 generates a pressure difference between the common supply flow path 211 and the common recovery flow path 212. For this reason, as shown in Figures 8 and 9, in the liquid ejection head of this application example in which the flow paths are connected, an ink flow is generated that flows in the order of the common supply flow path 211 -> the individual supply flow path 213 -> the recording element substrate 10 -> the individual recovery flow path 214 -> the common recovery flow path 212 for each ink color.

[0045] <Explanation of the discharge module> FIG. 10(a) is a perspective view showing one discharge module 200, and FIG. 10(b) is an exploded view thereof. In the manufacturing method of the discharge module 200, first, the recording element substrate 10 and the flexible wiring substrate 40 are bonded onto the support member 30 in which the liquid communication port 31 is provided in advance. Then, the terminal 16 on the recording element substrate 10 and the terminal 41 on the flexible wiring substrate 40 are electrically connected by wire bonding, and then the wire bonding portion (electrical connection portion) is covered and sealed with a sealant 110. The terminal 42 on the flexible wiring substrate 40 opposite the recording element substrate 10 is electrically connected to the connection terminal 93 (see FIG. 6) of the electrical wiring substrate 90. The support member 30 is a support for supporting the recording element substrate 10 and is also a flow path member for fluidly communicating the recording element substrate 10 and the flow path member 210, so it is preferable that the support member 30 has a high flatness and can be joined to the recording element substrate with sufficiently high reliability. For example, alumina or a resin material is preferable as the material.

[0046] <Explanation of the structure of the recording element substrate> FIG. 11(a) shows a plan view of the surface of the recording element substrate 10 on which the ejection ports 13 are formed, FIG. 11(b) shows an enlarged view of the portion indicated by A in FIG. 11(a), and FIG. 11(c) shows a plan view of the back surface of FIG. 11(a). Here, the configuration of the recording element substrate 10 in this application example will be described. As shown in FIG. 11(a), four ejection port arrays corresponding to each ink color are formed in the ejection port forming member 12 of the recording element substrate 10. Hereinafter, the direction in which the ejection port array in which the multiple ejection ports 13 are arranged extends will be referred to as the "ejection port array direction". As shown in FIG. 11(b), a recording element 15, which is a heat generating element for foaming the liquid by thermal energy, is arranged at a position corresponding to each ejection port 13. A pressure chamber 23 having the recording element 15 therein is partitioned by a partition wall 22. The recording element 15 is electrically connected to a terminal 16 by an electric wiring (not shown) provided on the recording element substrate 10. The recording elements 15 generate heat based on a pulse signal input from the control circuit of the recording device 1000 via the electric wiring board 90 (see FIG. 6) and the flexible wiring board 40 (see FIG. 10) to boil the liquid. The liquid is ejected from the ejection ports 13 by the bubbling force caused by this boiling. As shown in FIG. 11(b), along each ejection port row, a liquid supply path 18 extends on one side, and a liquid recovery path 19 extends on the other side. The liquid supply path 18 and the liquid recovery path 19 are flow paths that extend in the ejection port row direction and are provided in the recording element substrate 10, and communicate with the ejection ports 13 via the supply port 17a and the recovery port 17b, respectively.

[0047] As shown in FIG. 11(c), a sheet-like cover plate 20 is laminated on the back surface of the recording element substrate 10, opposite to the surface on which the ejection ports 13 are formed, and the cover plate 20 is provided with a plurality of openings 21 communicating with the liquid supply passage 18 and the liquid recovery passage 19, which will be described later. In this application example, the cover plate 20 is provided with three openings 21 for each of the liquid supply passages 18 and two openings 21 for each of the liquid recovery passages 19. As shown in FIG. 11(b), each opening 21 of the cover plate 20 communicates with a plurality of communication ports 51 shown in FIG. 7(a). The cover plate 20 is preferably a material having sufficient corrosion resistance against liquid, and from the viewpoint of preventing color mixing, high accuracy is required for the opening shape and opening position of the opening 21. For this reason, it is preferable to use a photosensitive resin material or a silicon plate as the material of the cover plate 20, and to provide the openings 21 by a photolithography process. In this way, the cover plate 20 changes the pitch of the flow passages by the openings 21, and it is preferable that the cover plate 20 is thin in thickness in consideration of pressure loss, and is preferably made of a film-like material.

[0048] FIG. 12 is a perspective view showing a cross section of the recording element substrate 10 and the cover plate 20 at XII-XII in FIG. 11(a). Here, the flow of liquid in the recording element substrate 10 will be described. The cover plate 20 functions as a lid that forms part of the walls of the liquid supply path 18 and the liquid recovery path 19 formed in the substrate 11 of the recording element substrate 10. The recording element substrate 10 is formed by laminating the substrate 11 made of Si and the ejection port forming member 12 made of a photosensitive resin, and the cover plate 20 is bonded to the back surface of the substrate 11. The recording elements 15 are formed on one surface of the substrate 11 (see FIG. 11), and grooves that form the liquid supply path 18 and the liquid recovery path 19 extending along the ejection port row are formed on the back surface. The liquid supply path 18 and the liquid recovery path 19 formed by the substrate 11 and the cover plate 20 are connected to a common supply path 211 and a common recovery path 212 in the flow path member 210, respectively, and a pressure difference is generated between the liquid supply path 18 and the liquid recovery path 19. When liquid is discharged from the ejection port 13 to perform recording, in the ejection port not performing ejection, the liquid in the liquid supply path 18 provided in the substrate 11 flows to the liquid recovery path 19 via the supply port 17a, the pressure chamber 23, and the recovery port 17b due to this pressure difference (arrow C in FIG. 12). This flow allows the thickened ink, bubbles, foreign matter, and the like generated by evaporation from the ejection port 13 to be recovered to the liquid recovery path 19 in the ejection port 13 and the pressure chamber 23 not performing the ejection operation. In addition, it is possible to suppress the ink in the ejection port 13 and the pressure chamber 23 from becoming thicker and the concentration of the coloring material from increasing. The liquid recovered to the liquid recovery path 19 passes through the opening 21 of the cover plate 20 and the liquid communication port 31 (see FIG. 10b) of the support member 30, and is recovered in this order to the communication port 51 in the flow path member 210, the individual recovery flow path 214, and the common recovery flow path 212. The liquid is then recovered from the liquid ejection head 3 to the supply path of the recording device 1000. In other words, the liquid supplied from the recording device body to the liquid ejection head 3 flows, and is supplied and recovered in the following order.

[0049] The liquid first flows into the liquid ejection head 3 from the liquid connection portion 111 of the liquid supply unit 220. The liquid is then supplied in the order of the joint rubber 100, the communication port 72 and the common flow channel 71 provided in the third flow channel member, the common flow channel 62 and the communication port 61 provided in the second flow channel member, and the individual flow channel 52 and the communication port 51 provided in the first flow channel member. Thereafter, the liquid is supplied to the pressure chamber 23 via the liquid communication port 31 provided in the support member 30, the opening 21 provided in the cover plate 20, the liquid supply path 18 and the supply port 17a provided in the substrate 11, in that order. Of the liquid supplied to the pressure chamber 23, the liquid that is not ejected from the ejection port 13 flows in the order of the recovery port 17b and the liquid recovery path 19 provided in the substrate 11, the opening 21 provided in the cover plate 20, and the liquid communication port 31 provided in the support member 30. The liquid then flows in this order through the communication port 51 and the individual flow path grooves 52 provided in the first flow path member, the communication port 61 and the common flow path groove 62 provided in the second flow path member, the common flow path groove 71 and the communication port 72 provided in the third flow path member 70, and the joint rubber 100. The liquid then flows from the liquid connection part 111 provided in the liquid supply unit 220 to the outside of the liquid ejection head 3.

[0050] In the first circulation mode shown in FIG. 2, the liquid flowing in from the liquid connection part 111 is supplied to the joint rubber 100 after passing through the negative pressure control unit 230. In the second circulation mode shown in FIG. 3, the liquid collected from the pressure chamber 23 passes through the joint rubber 100, and then flows from the liquid connection part 111 to the outside of the liquid ejection head via the negative pressure control unit 230. In addition, not all of the liquid flowing in from one end of the common supply flow path 211 of the liquid ejection unit 300 is supplied to the pressure chamber 23 via the individual supply flow path 213a. In other words, some of the liquid flowing in from one end of the common supply flow path 211 flows from the other end of the common supply flow path 211 to the liquid supply unit 220 without flowing into the individual supply flow path 213a. In this way, by providing a path that does not pass through the recording element substrate 10, it is possible to suppress backflow of the circulating flow of the liquid even when using a recording element substrate 10 that has a fine flow path with a relatively large flow resistance as in this application example. In this way, in the liquid ejection head 3 of this application example, it is possible to suppress thickening of the liquid in the pressure chamber 23 and in the vicinity of the ejection port, thereby suppressing distorted ejection and non-ejection, and as a result, high-quality recording can be performed.

[0051] <Description of the positional relationship between the recording element substrates> FIG. 13 is a partially enlarged plan view showing adjacent portions of the recording element substrates in two adjacent discharge modules 200. In this application example, a recording element substrate having a shape of a parallelogram is used. Each discharge port array (14a to 14d) in which the discharge ports 13 in each recording element substrate 10 are arranged so as to be inclined at a certain angle with respect to the conveying direction of the recording medium. In addition, the discharge port arrays in the adjacent portions of the recording element substrates 10 are arranged so that at least one discharge port overlaps with the conveying direction of the recording medium. In FIG. 13, two discharge ports on a line D are in a mutually overlapping relationship. With this arrangement, even if the position of the recording element substrate 10 is slightly deviated from the predetermined position, black stripes and white spots in the recorded image can be made less noticeable by driving control of the overlapping discharge ports. Even if multiple recording element substrates 10 are arranged in a straight line (inline) rather than in a so-called staggered arrangement, measures can be taken against black stripes and white spots at the joints. 13, it is possible to prevent black streaks and white spots at the joints between the recording element substrates 10 while suppressing an increase in the length of the liquid ejection head 3 in the recording medium transport direction. Note that, in this application example, the main plane of the recording element substrate is a parallelogram, but this is not limited thereto, and the configuration of the present invention can be preferably applied even when a recording element substrate having a rectangular, trapezoidal, or other shape is used.

[0052] <Description of Modified Examples of Liquid Ejection Head Configuration> A modified example of the liquid ejection head configuration described above will be described with reference to FIG. 46, FIG. 48 to FIG. 50. The description of the same configuration and function as the above-mentioned example will be omitted, and the differences will be mainly described. In this modified example, as shown in FIG. 46 and FIG. 48, a plurality of liquid connection parts 111, which are liquid connection parts between the liquid ejection head 3 and the outside, are arranged in a concentrated manner at one end side in the longitudinal direction of the liquid ejection head. A plurality of negative pressure control units 230 are arranged in a concentrated manner at the other end side of the liquid ejection head 3 (FIG. 49). The liquid supply unit 220 included in the liquid ejection head 3 is configured as an elongated unit corresponding to the length of the liquid ejection head 3, and includes flow paths and filters 221 corresponding to the four colors of liquid to be supplied. As shown in FIG. 49, the positions of the openings 83 to 86 provided in the liquid ejection unit support part 81 are also provided at positions different from those of the above-mentioned liquid ejection head 3.

[0053] FIG. 50 shows the stacked state of the flow path members 50, 60, 70. A plurality of recording element substrates 10 are linearly arranged on the upper surface of the flow path member 50, which is the uppermost layer of the plurality of flow path members 50, 60, 70. The flow paths communicating with the openings 21 (FIG. 19) formed on the rear surface side of each recording element substrate 10 include two individual supply flow paths 213 and one individual recovery flow path 214 for each color of liquid. Correspondingly, the openings 21 formed in the cover plate 20 provided on the rear surface of the recording element substrate 10 also include two supply openings 21 and one recovery opening 21 for each color of liquid. As shown in FIG. 50, the common supply flow path 211 and the common recovery flow path 212 extending along the longitudinal direction of the liquid ejection head 3 are alternately arranged in parallel.

[0054] (Second application example) <Inkjet recording device> Next, the configuration of an inkjet recording apparatus 2000 and a liquid ejection head 2003 according to a second application example, which differs from the inkjet recording apparatus according to the first application example described above, will be described. In the following description, mainly only the parts that differ from the recording apparatus according to the first application example will be described, and the parts that are the same as those of the apparatus according to the first application example will not be described.

[0055] FIG. 21 is a diagram showing an inkjet recording apparatus 2000 according to the second application example. The recording apparatus 2000 according to this application example is different from the first application example in that full-color recording is performed on a recording medium by arranging four single-color liquid ejection heads 2003 corresponding to each ink of cyan C, magenta M, yellow Y, and black K in parallel. In the first application example, the number of ejection port rows that can be used per color is one row, whereas in this application example, the number of ejection port rows that can be used per color is 20 rows. Therefore, by appropriately allocating the recording data to the multiple ejection port rows and performing recording, very high-speed recording is possible. Furthermore, even if there is an ejection port that does not eject, reliability is improved by performing interpolation ejection from the ejection port of another row that is located at a position corresponding to the conveyance direction of the recording medium with respect to the ejection port, which is suitable for commercial recording. As in the first application example, the supply system of the recording apparatus 2000, the buffer tank 1003 (see FIG. 2 and FIG. 3), and the main tank 1006 (see FIG. 2 and FIG. 3) are fluidly connected to each liquid ejection head 2003. Further, each liquid ejection head 2003 is electrically connected to an electric control unit that transmits power and ejection control signals to the liquid ejection head 2003 .

[0056] <Explanation of the circulation route> As in the first application example, the first to third circulation forms shown in FIG. 2, FIG. 3, and FIG. 47 can be used as the liquid circulation path between the recording device 2000 and the liquid ejection head 2003, as in the first application example.

[0057] <Explanation of liquid ejection head structure> 14(a) and (b) are perspective views showing a liquid ejection head 2003 according to this application example. The liquid ejection head 2003 is a line-type print head that includes 16 recording element substrates 2010 arranged in a straight line in the longitudinal direction of the liquid ejection head 2003 and ejects ink of one color. The liquid ejection head 2003 includes a liquid connection portion 111, a signal input terminal 91, and a power supply terminal 92, as in the first application example. However, the liquid ejection head 2003 of this embodiment has more ejection port rows than the head of the first application example, and therefore the signal output terminals 91 and the power supply terminals 92 are arranged on both sides of the liquid ejection head 2003. This makes it possible to reduce voltage drops and signal transmission delays that occur in the wiring portion provided on the recording element substrate 2010.

[0058] FIG. 15 is an exploded perspective view showing the liquid ejection head 2003, and each part or unit constituting the liquid ejection head 2003 is shown divided according to its function. The role of each unit and member and the order of liquid flow in the liquid ejection head are basically the same as those in the first application example, but the function of ensuring the rigidity of the liquid ejection head is different. In the first application example, the rigidity of the liquid ejection head is mainly ensured by the liquid ejection unit support part 81, but in the liquid ejection head 2003 of the second application example, the rigidity of the liquid ejection head is ensured by the second flow path member 2060 included in the liquid ejection unit 2300. The liquid ejection unit support part 81 in this application example is connected to both ends of the second flow path member 2060, and this liquid ejection unit 2300 is mechanically connected to the carriage of the recording device 2000 to position the liquid ejection head 2003. The liquid supply unit 2220 including the negative pressure control unit 2230 and the electric wiring board 90 are connected to the liquid ejection unit support part 81. Each of the two liquid supply units 2220 has a built-in filter (not shown).

[0059] The two negative pressure control units 2230 are set to control pressure at different, relatively high and low negative pressures. Also, as shown in FIG. 14, when the high-pressure and low-pressure negative pressure control units 2230 are installed at both ends of the liquid ejection head 2003, the liquid flows in the common supply flow path and the common recovery flow path extending in the longitudinal direction of the liquid ejection head 2003 face each other. In this configuration, heat exchange is promoted between the common supply flow path and the common recovery flow path, and the temperature difference in the two common flow paths is reduced. This has the advantage of reducing the temperature difference in each of the recording element substrates 2010 provided along the common flow path, making it less likely that recording unevenness due to temperature differences will occur.

[0060] Next, the flow path member 2210 of the liquid discharge unit 2300 will be described in detail. As shown in FIG. 15, the flow path member 2210 is a laminate of a first flow path member 2050 and a second flow path member 2060, and distributes the liquid supplied from the liquid supply unit 2220 to each discharge module 2200. The flow path member 2210 also functions as a flow path member for returning the liquid circulating from the discharge module 2200 to the liquid supply unit 2220. The second flow path member 2060 of the flow path member 2210 is a flow path member in which a common supply flow path and a common recovery flow path are formed, and also has a function of mainly taking charge of the rigidity of the liquid discharge head 2003. For this reason, the material of the second flow path member 2060 is preferably one having sufficient corrosion resistance against liquid and high mechanical strength. Specifically, SUS, Ti, alumina, etc. can be used.

[0061] FIG. 16(a) is a diagram showing the surface of the first flow path member 2050 on which the discharge module 2200 is mounted, and FIG. 16(b) is a diagram showing the back surface thereof, which is a diagram showing the surface that abuts against the second flow path member 2060. Unlike the first application example, the first flow path member 2050 in this embodiment is formed by arranging a plurality of members corresponding to each discharge module 2200 adjacent to each other. By adopting such a divided structure, it is possible to arrange a plurality of modules to correspond to the length of the liquid discharge head 2003, and therefore it is particularly suitable for application to a relatively long-scale liquid discharge head corresponding to, for example, B2 size or longer. As shown in FIG. 16(a), the communication port 51 of the first flow path member 2050 is fluidically connected to the discharge module 2200, and as shown in FIG. 16(b), the individual communication port 53 of the first flow path member 2050 is fluidically connected to the communication port 61 of the second flow path member 2060. FIG. 16(c) shows the surface of the second flow path member 60 that comes into contact with the first flow path member 2050, FIG. 16(d) shows a cross section of the second flow path member 60 at the center in the thickness direction, and FIG. 16(e) shows the surface of the second flow path member 2060 that comes into contact with the liquid supply unit 2220. The functions of the flow paths and communication ports of the second flow path member 2060 are the same as those of one color in the first application example. The common flow path groove 71 of the second flow path member 2060 is a common supply flow path 2211 shown in FIG. 17 described later on one side, and a common recovery flow path 2212 on the other side, each of which is provided along the longitudinal direction of the liquid ejection head 2003, and liquid is supplied from one end side to the other end side. In this embodiment, unlike the first application example, the liquid flows in the common supply flow path 2211 and the common recovery flow path 2212 in opposite directions.

[0062] 17 is a perspective view showing the liquid connection relationship between the recording element substrate 2010 and the flow path member 2210. A set of a common supply flow path 2211 and a common recovery flow path 2212 extending in the longitudinal direction of the liquid ejection head 2003 is provided in the flow path member 2210. The communication port 61 of the second flow path member 2060 is aligned and connected to the individual communication port 53 of each of the first flow path members 50. In addition, a liquid supply path is formed that communicates from the communication port 72 of the second flow path member 2060 to the communication port 51 of the first flow path member 2050 via the common supply flow path 2211. Similarly, a liquid supply path is also formed that communicates from the communication port 72 of the second flow path member 2060 to the communication port 51 of the first flow path member 2050 via the common recovery flow path 2212.

[0063] FIG. 18 is a diagram showing a cross section taken along line XVIII-XVIII in FIG. 17. The common supply flow path 2211 is connected to the discharge module 2200 via the communication port 61, the individual communication port 53, and the communication port 51. Although not shown in FIG. 18, it is clear from FIG. 17 that the common recovery flow path 2212 is connected to the discharge module 2200 via a similar route in another cross section. As in the first application example, each discharge module 2200 and the recording element substrate 2010 are formed with a flow path communicating with each discharge port, so that a part or all of the supplied liquid can be circulated by passing through the discharge port that is not discharging. Also, as in the first application example, the common supply flow path 2211 is connected to the negative pressure control unit 2230 (high pressure side), and the common recovery flow path 2212 is connected to the negative pressure control unit 2230 (low pressure side), respectively, via the liquid supply unit 2220. Therefore, due to the pressure difference, a flow is generated that flows from the common supply flow path 2211 through the ejection ports of the recording element substrate 2010 to the common recovery flow path 2212 .

[0064] <Explanation of the discharge module> FIG. 19(a) is a perspective view showing one discharge module 2200, and FIG. 19(b) is an exploded view thereof. The difference from the first application example is that a plurality of terminals 16 are arranged on both sides (each long side of the recording element substrate 2010) along the direction of the plurality of discharge port arrays of the recording element substrate 2010. Accordingly, two flexible wiring substrates 40 electrically connected to the recording element substrate 2010 are arranged for one recording element substrate 2010. This is because the number of discharge port arrays provided on the recording element substrate 2010 is 20, which is significantly increased from the eight arrays in the first application example, and this is to reduce the maximum distance from the terminals 16 to the recording elements and reduce voltage drops and signal delays that occur in the wiring portion in the recording element substrate 2010. In addition, the liquid communication port 31 of the support member 2030 is provided on the recording element substrate 2010 and opens so as to straddle all the discharge port arrays. Other points are the same as those of the first application example.

[0065] <Explanation of the structure of the recording element substrate> FIG. 20(a) is a schematic diagram of the surface of the recording element substrate 2010 on which the ejection ports 13 are arranged, and FIG. 20(c) is a schematic diagram showing the back surface of the surface of FIG. 20(a). FIG. 20(b) is a schematic diagram showing the surface of the recording element substrate 2010 when the cover plate 2020 provided on the back surface side of the recording element substrate 2010 in FIG. 20(c) is removed. As shown in FIG. 20(b), the liquid supply path 18 and the liquid recovery path 19 are alternately provided along the ejection port array direction on the back surface of the recording element substrate 2010. Although the number of ejection port arrays is significantly increased compared to the first application example, the essential difference from the first application example is that the terminals 16 are arranged on both sides of the recording element substrate along the ejection port array direction, as described above. The basic configuration is the same as in the first application example, in that a set of liquid supply path 18 and liquid recovery path 19 is provided for each row of ejection ports, and an opening 21 is provided in the cover plate 2020 that communicates with the liquid communication port 31 of the support member 2030.

[0066] (Third application example) <Inkjet recording device> The configuration of an inkjet recording apparatus 1000 and a liquid ejection head 3 according to a third application example of the present invention will be described. The liquid ejection head of the third application example is a page-wide type that performs recording on a B2 size recording medium in one scan. Since the third application example has many similarities to the second application example, the following explanation will mainly describe the parts that differ from the second application example, and will omit explanations of the parts that are similar to the second application example.

[0067] FIG. 51 shows a schematic diagram of an inkjet recording device of this application example. The recording device 1000 does not directly record on a recording medium from the liquid ejection head 3, but ejects liquid onto an intermediate transfer body (intermediate transfer drum 1007) to form an image, and then transfers the image to a recording medium 2. In the recording device 1000, four single-color liquid ejection heads 3 corresponding to four types of ink, CMYK, are arranged in an arc shape along the intermediate transfer drum 1007. This allows full-color recording on the intermediate transfer body, and the recorded image is appropriately dried on the intermediate transfer body, and then transferred by a transfer unit 1008 to the recording medium 2 transported by a paper transport roller 1009. While the paper transport system of the second application example was a horizontal transport intended mainly for cut paper, this application example can also handle continuous paper supplied from a main roll (not shown). With such a drum transport system, it is easy to transport the paper while applying a certain tension, so transport jams are rare even during high-speed recording. This improves the reliability of the device, making it suitable for commercial printing and the like. As in the first and second application examples, the supply system, buffer tank 1003, and main tank 1006 of the recording apparatus 1000 are fluidly connected to each liquid ejection head 3. In addition, each liquid ejection head 3 is electrically connected to an electric control unit that transmits power and ejection control signals to the liquid ejection head 3.

[0068] <Explanation of the fourth circulation type> As the liquid circulation path in this application example, the first to third circulation paths shown in Fig. 2, Fig. 3, and Fig. 47 can also be applied, but the circulation path shown in Fig. 52 is more preferably applied. It is similar to the second circulation path in Fig. 3, but the main difference is that a bypass valve 1010 communicating with the flow path of each of the first circulation pumps 1001 and 1002 and the second circulation pump 1004 is added. This bypass valve 1010 has a function (first function) of lowering the pressure upstream of the bypass valve 1010 by opening the valve when the pressure exceeds a preset pressure. It also has a function (second function) of opening and closing the valve at any timing according to a signal from the control board of the recording apparatus main body.

[0069] The first function can prevent excessive or insufficient pressure from being applied to the flow path downstream of the first circulating pumps 1001, 1002 or upstream of the second circulating pump 1004. For example, if the first circulating pumps 1001, 1002 fail to function, excessive flow rate or pressure may be applied to the liquid ejection head 3. This may cause liquid to leak from the ejection ports of the liquid ejection head 3 or cause breakage at each joint in the liquid ejection head 3. However, as in this application example, if bypass valves are added to the first circulating pumps 1001, 1002, the bypass valve 1010 opens to open the liquid path to the upstream side of each circulating pump even if excessive pressure is generated, and the above-mentioned troubles can be prevented.

[0070] In addition, due to the second function, when the circulation drive is stopped, after the first circulation pumps 1001, 1002 and the second circulation pump 1004 are stopped, all the bypass valves 1010 are quickly opened based on a control signal from the main body side. This allows the high negative pressure (for example, several to several tens of kPa) in the downstream part of the liquid discharge head 3 (between the negative pressure control unit 230 and the second circulation pump 1004) to be released in a short time. When a volumetric pump such as a diaphragm pump is used as the circulation pump, a check valve is usually built into the pump. However, by opening the bypass valve, the pressure in the downstream part of the liquid discharge head 3 can be released from the downstream buffer tank 1003 side as well. Although the pressure in the downstream part of the liquid discharge head 3 can be released only from the upstream side, there is a pressure loss in the upstream flow path of the liquid discharge head and the flow path inside the liquid discharge head. Therefore, it takes time to release the pressure, and the pressure in the common flow path in the liquid discharge head 3 drops too much transiently, which may destroy the meniscus of the discharge port. By opening the bypass valve 1010 downstream of the liquid ejection head 3, pressure release downstream of the liquid ejection head is promoted, thereby reducing the risk of meniscus destruction at the ejection port.

[0071] (Explanation of liquid ejection head structure) The structure of a liquid ejection head 3 according to a third application example of the present invention will be described. Fig. 53(a) is a perspective view of the liquid ejection head 3 according to this application example, and Fig. 53(b) is an exploded perspective view thereof. The liquid ejection head 3 is an inkjet page-wide type recording head that includes 36 recording element substrates 10 arranged in a straight line (inline) in the longitudinal direction of the liquid ejection head 3 and performs recording with one color of liquid. As with the second application example, the liquid ejection head 3 includes a signal input terminal 91 and a power supply terminal 92, and is also provided with a shield plate 132 that protects the longitudinal side surfaces of the head.

[0072] FIG. 53(b) is an exploded perspective view of the liquid ejection head 3, in which each part or unit constituting the liquid ejection head 3 is divided and displayed according to its function (shield plate 132 is not shown). The role of each unit and each member, and the order of liquid flow in the liquid ejection head 3 are the same as those in the second application example. The main differences from the second application example are the electric wiring boards 90, which are divided and arranged in a plurality of parts, the position of the negative pressure control unit 230, and the shape of the first flow path member. In the case of a liquid ejection head 3 having a length corresponding to a B2 size recording medium as in this application example, eight electric wiring boards 90 are provided because the electric power used by the liquid ejection head 3 is large. Four electric wiring boards 90 are attached to each side of a long electric wiring board support part 82 attached to a liquid ejection unit support part 81.

[0073] Fig. 54(a) is a side view of a liquid ejection head 3 equipped with a liquid ejection unit 300, a liquid supply unit 220, and a negative pressure control unit 230, Fig. 54(b) is a schematic diagram showing the flow of liquid, and Fig. 54(c) is a perspective view showing a cross section taken along line GG in Fig. 54(a). To facilitate understanding, some components have been simplified.

[0074] The liquid supply unit 220 is provided with a liquid connection part 111 and a filter 221, and a negative pressure control unit 230 is integrally formed below the liquid supply unit 220. This makes the distance in the height direction between the negative pressure control unit 230 and the recording element substrate 10 shorter than in the second application example. This configuration has the advantage that the number of flow path connections in the liquid supply unit 220 is reduced, improving reliability against leakage of the recording liquid as well as reducing the number of parts and the number of assembly steps.

[0075] In addition, since the head difference between the negative pressure control unit 230 and the surface on which the ejection ports are formed is relatively small, this can be suitably applied to a recording device in which the inclination angle of the liquid ejection head 3 differs for each liquid ejection head, as shown in Fig. 51. Since the head difference can be made small, even if multiple liquid ejection heads 3 are used at different inclination angles, the negative pressure difference applied to the ejection ports of each recording element substrate can be reduced. In addition, since the distance between the negative pressure control unit 230 and the recording element substrate 10 is reduced, the flow resistance therebetween is reduced, and the pressure loss difference due to changes in the liquid flow rate is also reduced, which is preferable in that more stable negative pressure control can be performed.

[0076] FIG. 54(b) is a schematic diagram showing the flow of the recording liquid inside the liquid ejection head 3. Although the circuit is the same as that of the circulation path shown in FIG. 52, FIG. 54(b) shows the flow of the liquid inside each component of the actual liquid ejection head 3. A set of common supply flow path 211 and common recovery flow path 212 extending in the longitudinal direction of the liquid ejection head 3 is provided inside the long second flow path member 60. The common supply flow path 211 and the common recovery flow path 212 are configured so that the liquid flows in the directions opposite to each other, and a filter 221 is provided on the upstream side of each flow path to trap foreign matter entering from the connection part 111, etc. In this way, the common supply flow path 211 and the common recovery flow path 212 are preferable in that the temperature gradient in the longitudinal direction inside the liquid ejection head 3 is reduced by flowing the liquid in the directions opposite to each other. In FIG. 52, the flow of the common supply flow path 211 and the common recovery flow path 212 is shown in the same direction to simplify the explanation.

[0077] A negative pressure control unit 230 is connected to the downstream side of each of the common supply flow path 211 and the common recovery flow path 212. In addition, the common supply flow path 211 has a branching portion into a plurality of individual supply flow paths 213a, and the common recovery flow path 212 has a branching portion into a plurality of individual recovery flow paths 213b. The individual supply flow paths 213a and the individual recovery flow paths 213b are formed in a plurality of first flow path members 50, and each individual flow path communicates with an opening 21 (see FIG. 19(c)) of a cover plate 20 provided on the back surface of the recording element substrate 10.

[0078] The negative pressure control unit 230 indicated by H and L in FIG. 54(b) is a unit having a high pressure side (H) and a low pressure side (L). Each negative pressure control unit 230 is a back pressure type pressure adjustment mechanism set to control the pressure upstream of the negative pressure control unit 230 with relatively high (H) and low (L) negative pressures. The common supply flow path 211 is connected to the negative pressure control unit 230 (high pressure side), and the common recovery flow path 212 is connected to the negative pressure control unit 230 (low pressure side), so that a pressure difference occurs between the common supply flow path 211 and the common recovery flow path 212. Due to the pressure difference, the liquid flows from the common supply flow path 211 to the individual supply flow paths 213a, the ejection port 13 (pressure chamber 23) in the recording element substrate 10, and the individual recovery flow path 213b in this order, and then to the common recovery flow path 212.

[0079] FIG. 54(c) is a perspective view showing a cross section at the line GG in FIG. 54(a). In this application example, each ejection module 200 is composed of a first flow path member 50, a recording element substrate 10, and a flexible wiring substrate 40. In this embodiment, there is no support member 30 (FIG. 18) described in the second application example, and the recording element substrate 10 having a cover plate 20 is directly joined to the first flow path member 50. The common supply flow path 211 provided in the second flow path member is supplied to the individual supply flow path 213a from the communication port 61 formed on the upper surface thereof through the individual communication port 53 formed on the lower surface of the first flow path member 50. The liquid is then recovered to the common recovery flow path 212 via the pressure chamber 23, the individual recovery flow path 213b, the individual communication port 53, and the communication port 61 in this order.

[0080] 15, the individual communication ports 53 on the lower surface (the surface on the second flow path member 60 side) of the first flow path member 50 are openings that are sufficiently large relative to the communication ports 61 formed on the upper surface of the second flow path member 50. With this configuration, even if the position of the ejection module 200 is misaligned when mounting it on the second flow path member 60, fluid communication is ensured between the first flow path member and the second flow path member, thereby improving the yield during head manufacturing and reducing costs.

[0081] The first to third application examples to which the present invention can be applied have been described above, but the description of the above application examples does not limit the scope of the present invention. As an example, the thermal method of discharging liquid by generating bubbles by heating a heat generating element has been described in this application example, but the present invention can also be applied to liquid discharge heads that employ a piezo method or various other liquid discharge methods.

[0082] In this application example, an inkjet recording device (recording device) in a form in which liquid such as ink is circulated between a tank and a liquid ejection head has been described, but other forms may also be used. As another form, for example, a form in which the ink is not circulated, but two tanks are provided on the upstream side and downstream side of the liquid ejection head, and the ink is caused to flow from one tank to the other tank, thereby causing the ink to flow in the pressure chamber.

[0083] In addition, in this application example, an example using a so-called page-wide type head having a length corresponding to the width of the recording medium has been described, but the present invention can also be applied to a so-called serial type liquid ejection head that performs printing while scanning the recording medium. An example of a serial type liquid ejection head is a configuration in which one recording element substrate for ejecting black ink and one recording element substrate for ejecting color ink are mounted, but the present invention is not limited to this. In other words, a short liquid ejection head shorter than the width of the recording medium may be created by arranging multiple recording element substrates so that the ejection openings overlap in the ejection opening row direction, and the liquid ejection head may be made to scan the recording medium.

[0084] Next, embodiments will be described that more specifically describe the features of the present invention.

[0085] (First embodiment) Figures 22(a) to (c) are diagrams illustrating the structure of an ejection port and an ink flow path in the vicinity thereof in a liquid ejection head according to a first embodiment of the present invention. Figure 22(a) is a plan view of the ink flow path and the like as viewed from the side from which ink is ejected, Figure 22(b) is a cross-sectional view taken along line A-A' in Figure 22(a), and Figure 22(c) is a perspective view of the cross-section taken along line A-A' in Figure 22(a).

[0086] As shown in these figures, due to the ink circulation described above with reference to FIG. 12 and the like, an ink flow 17 is generated in the pressure chamber 23 provided with the recording element 15 on the substrate 11 of the liquid ejection head and the flow paths 24 before and after it. That is, due to the differential pressure that causes ink circulation, the ink supplied from the liquid supply path (supply flow path) 18 through the supply port 17 provided in the substrate 11 passes through the flow path 24, the pressure chamber 23, and the flow path 24, and generates a flow that reaches the liquid recovery path (outflow flow path) 19 through the recovery port 17b.

[0087] Along with the above-described ink flow, when not ejecting, the space from the recording element (energy generating element) 15 to the ejection port 13 above it is filled with ink, and an ink meniscus (ink interface 13a) is formed near the end portion on the ejection direction side of the ejection port 13. In FIG. 22(b), this ink interface is represented by a straight line (plane), but its shape is determined according to the member forming the wall of the ejection port 13 and the surface tension of the ink, and usually becomes a concave or convex curved line (curved surface). It is represented by a straight line to simplify the illustration. In the state where this meniscus is formed, by driving the electrothermal conversion element (heater), which is the energy generating element 15, the heat generated is used to generate bubbles in the ink, and the ink can be ejected from the ejection port 13. In addition, in this embodiment, an example in which a heater is applied as the energy generating element is described, but the present invention is not limited to this, and for example, various energy generating elements such as piezoelectric elements can be applied. In this embodiment, the speed of the ink flow flowing through the flow path 24 is, for example, about 0.1 to 100 mm / s, and even when the ejection operation is performed with the ink flowing, the influence on the landing accuracy and the like can be made relatively small.

[0088] <Regarding the relationship among P, W, and H> In the liquid ejection head of this embodiment, the relationship among the height H of its flow path 24, the thickness P of the orifice plate (flow path forming member 12), and the length (diameter) W of the ejection port is determined as described below.

[0089] In FIG. 22(b), the height of the upstream side of the flow path 24 at the lower end (the portion communicating between the ejection port and the flow path) of a portion of the orifice plate with thickness P of the ejection port 13 (hereinafter referred to as ejection port portion 13B) is indicated as H. The length of the ejection port portion 13b is indicated as P. Furthermore, the length of the ejection port portion 13b in the direction of the flow of the liquid in the flow path 24 is indicated as W. In the liquid ejection head of this embodiment, H is 3 to 30 μm, P is 3 to 30 μm, and W is 6 to 30 μm. The ink has a non-volatile solvent concentration of 30%, a colorant concentration of 3%, and a viscosity adjusted to 0.002 to 0.01 Pa s.

[0090] In this embodiment, the following is done to suppress thickening of ink due to evaporation of ink from the ejection port 13. Fig. 43 is a diagram showing the state of the ink flow 17 in the ejection port 13, ejection port portion 13b, and flow channel 24 when the ink flow 17 (see Fig. 22) of the ink flowing in the flow channel 24 and pressure chamber 23 of the liquid ejection head reaches a steady state. Note that in this figure, the length of the arrow does not indicate the magnitude of the ink flow velocity. Fig. 43 shows a liquid ejection head in which the height H of the flow channel 24 is 14 µm, the length P of the ejection port portion 13b is 10 µm, and the length (diameter) W of the ejection port is 17 µm, and a flow of 1.26 × 10 -4 The figure shows the flow when ink flows in at a flow rate of ml / min.

[0091] In this embodiment, the height H of the flow path 24, the length P of the ejection port 13b, and the length W of the ejection port 13b in the ink flow direction have a relationship that satisfies the following formula (1). H -0.34 ×P -0.66 ×W>1.5 Formula (1)

[0092] In the liquid ejection head of the present embodiment, by satisfying this condition, as shown in FIG. 43, the ink flow 17 flowing in the flow path 24 flows into the ejection port 13b, reaches at least half the position of the orifice plate thickness of the ejection port 13b, and then returns to the flow path 24. The ink that has returned to the flow path 24 flows through the liquid recovery path 19 to the above-mentioned common recovery flow path 212. That is, at least a part of the ink flow 17 reaches a position of at least half of the ejection port 13b in the direction from the pressure chamber 23 toward the ink interface 13a, and then returns to the flow path 24. This flow can suppress the increase in ink viscosity in many areas in the ejection port 13b. By generating such an ink flow in the liquid ejection head, not only the ink in the flow path 24 but also the ink in the ejection port 13b can flow out to the flow path 24. As a result, it is possible to suppress the increase in ink viscosity and the increase in ink colorant concentration in the ejection port 13 and the ejection port 13b. The ink droplets ejected from the ejection port are ejected in a state where the ink in the ejection port portion 13b and the ink in the pressure chamber 23 (flow path 24) are mixed. In this embodiment, it is preferable that the ratio of the ink in the pressure chamber 23 (flow path 24) among the ejected droplets is higher. For example, it is preferable that the air bubbles generated during ejection communicate with the atmosphere. In particular, a liquid ejection head in which H is 20 μm or less, P is 20 μm or less, and W is 30 μm or less is preferable because it enables higher resolution recording. As described above, this embodiment can suppress fluctuations in the quality of the liquid near the ejection port, and for example, it is possible to suppress thickening of the ink due to evaporation of the liquid from the ejection port and reduce color unevenness in the image.

[0093] Second embodiment FIG. 23 is a diagram showing the flow of ink within a liquid ejection head according to a second embodiment of the present invention, and parts that are similar to those in the first embodiment described above are given the same symbols and will not be described.

[0094] This embodiment is configured as follows to further reduce the effects of ink viscosity increase due to evaporation of liquid from the ejection port. Fig. 23 is a diagram similar to Fig. 43, showing the state of the ink flow 17 in the ejection port 13, ejection port portion 13b, and flow path 24 when the ink flow 17 of ink flowing inside the liquid ejection head reaches a steady state. Note that in this figure, the length of the arrow does not correspond to the magnitude of the velocity, and is shown as a constant length regardless of the magnitude of the velocity. Fig. 23 shows the state of the ink flow 17 in the ejection port 13, the ejection port portion 13b, and the flow path 24 when the ink flow 17 of ink flowing inside the liquid ejection head reaches a steady state. -4 The flow rate of ink when it flows into the flow passage 24 is shown in ml / min.

[0095] In this embodiment, the height H of the flow path 24, the length P of the ejection port 13b, and the length W of the ejection port 13b in the ink flow direction satisfy the relationship of formula (2) described later. This makes it possible to suppress the ink, the coloring material concentration of which has changed or the viscosity of which has increased due to the evaporation of the ink from the ejection port, from staying near the ink interface 13a of the ejection port 13b, even more than in the first embodiment. That is, in the liquid ejection head of this embodiment, as shown in FIG. 23, the ink flow 17 flowing in the flow path 24 flows into the ejection port 13b, reaches the vicinity of the ink interface 13a (meniscus position), and then returns to the flow path 24 through the ejection port 13b again. The ink that has returned to the flow path 24 flows to the above-mentioned common recovery flow path 212 via the liquid recovery path 19. This ink flow allows the ink not only in the ejection port 13b, which is easily affected by evaporation, but also in the vicinity of the ink interface 13a, where the effect of evaporation is particularly noticeable, to flow out to the flow path 24 without staying inside the ejection port 13b. As a result, the ink can flow out without stagnation from the area near the ejection port that is particularly susceptible to the effects of evaporation of the ink moisture, etc., and the ink can be prevented from thickening or increasing in the ink colorant concentration. Since the present embodiment can prevent the viscosity increase of at least a part of the ink interface 13a, it is possible to further reduce the effects on ejection, such as changes in ejection speed, compared to when the viscosity increases over the entire ink interface 13a.

[0096] The ink flow 17 of this embodiment has a velocity component (hereinafter referred to as a positive velocity component) in the flow direction of the ink in the flow path 24 (direction from left to right in FIG. 23) at least in the central portion (center of the ejection port) in the vicinity of the ink interface 13a. In this specification, a flow mode in which the ink flow 17 has a positive velocity component at least in the central portion in the vicinity of the ink interface 13a is referred to as "flow mode A." Also, a flow mode in which the ink flow 17 has a negative velocity component in the opposite direction to the positive velocity component in the central portion of the ink interface 13a, as in the comparative column described later, is referred to as "flow mode B."

[0097] 24(a) and (b) are diagrams showing the state of the colorant concentration of the ink inside the ejection port portion 13b, with (a) showing the state of this embodiment and (b) showing the state of the comparative example. That is, (a) of FIG. 24 shows the case of flow mode A, and (b) of FIG. 24 shows the case of flow mode B according to the comparative example in which the flow near the center of the ink interface 13a inside the ejection port portion 13b has a negative velocity component. The contour lines shown in (a) and (b) of FIG. 24 show the distribution of the colorant concentration in the ink inside the ejection port portion 13b.

[0098] These flow modes A and B are determined by the values ​​of P, W, and H, which indicate the structure of the flow path, etc. In FIG. 24(a), a 1.26×10 -4 24(b) shows the state of flow mode A when the ink flows in at ml / min. On the other hand, FIG. 24(b) shows the state of flow mode A when the ink flows in at ml / min. -424(b) shows the state of flow mode B when ml / min of ink flows in. In flow mode B shown in FIG. 24(b), the colorant concentration of the ink inside the ejection port 13b is higher than in flow mode A shown in FIG. 24(a). That is, in flow mode A shown in FIG. 24(a), the ink inside the ejection port 13b can be replaced (flowed out) to the flow path 24 by the ink flow 17 that reaches the vicinity of the ink interface 13a with a positive velocity component. This makes it possible to suppress the ink from accumulating inside the ejection port 13b, and as a result, it becomes possible to suppress an increase in the colorant concentration and viscosity.

[0099] FIG. 25 is a diagram for explaining a comparison of the colorant densities of ink ejected from a liquid ejection head (head A) that generates flow mode A and a liquid ejection head (head B) that generates flow mode B. The figure shows data for each of head A and head B, in which ink is ejected with an ink flow 17 generated in the flow path 24, and in which ink is ejected without generating an ink flow 17 and without an ink flow in the flow path. In the figure, the horizontal axis indicates the time that has elapsed since ink was ejected from the ejection port, and the vertical axis indicates the colorant density ratio of dots formed on a recording medium by the ejected ink. This density ratio is the ratio of the density of dots formed by ink ejected after each elapsed time, when the density of dots formed by ink ejected at an ejection frequency of 100 Hz is set to 1.

[0100] As shown in FIG. 25, when the ink flow 17 is not generated, the concentration ratio becomes 1.3 or more in both heads A and B after 1 second or more, and the ink colorant concentration becomes high in a relatively short time. When the ink flow 17 is generated by head B, the concentration ratio is in the range of about 1.3, and the increase in the colorant concentration can be suppressed more than when the ink flow is not generated. However, ink with a high colorant concentration of up to 1.3 remains at the ejection port. In contrast, when the ink flow is generated by head A, the range of the colorant concentration ratio is 1.1 or less. It has been found from the study that if the colorant concentration change is about 1.2 or less, it is difficult for a person to visually recognize color unevenness. In other words, head A is more preferable than head B because it can suppress the change in colorant concentration to the extent that color unevenness can be visually recognized even if the elapsed time is about 1.5 seconds. Note that FIG. 25 shows the case where the colorant concentration becomes high due to evaporation, but the liquid ejection head of this embodiment can also suppress the change in colorant concentration when the colorant concentration becomes low due to evaporation.

[0101] Through investigations by the present inventors, it has been found that in the liquid ejection head generating flow mode A in this embodiment, the relationship between the height H of the flow path 24, the thickness P of the orifice plate (flow path forming member 12), and the length (diameter) W of the ejection port satisfies the following formula (2). H -0.34 ×P -0.66 ×W>1.7 Formula (2)

[0102] Hereinafter, the value on the left side of the above formula (2) will be referred to as the judgment value J. According to the study by the inventors of the present application, a liquid ejection head that satisfies formula (2) will result in flow mode A as shown in Fig. 23, while a liquid ejection head that generates flow mode B will not satisfy formula (2).

[0103] The formula (2) will be explained below.

[0104] Fig. 26 is a diagram showing the relationship between a liquid ejection head that generates flow mode A of the second embodiment and a liquid ejection head that generates flow mode B of a comparative example. The horizontal axis of Fig. 26 indicates the ratio of P to H (P / H), and the vertical axis indicates the ratio of W to P (W / P). A threshold line 20 is a line that satisfies the following formula (3). (W / P)=1.7×(P / H) -0.34 Formula (3)

[0105] 26, the relationship between H, P, and W is flow mode A for liquid ejection heads in the region indicated by diagonal lines above the threshold line 20, and flow mode B for liquid ejection heads in the region below and including the threshold line 20. In other words, flow mode A occurs in liquid ejection heads that satisfy the following formula (4). (W / P)>1.7×(P / H) -0.34 Formula (4)

[0106] Since equation (4) can be rearranged to obtain equation (2), heads in which the relationship between H, P, and W satisfies equation (2) (heads with a judgment value J of 1.7 or more) are in flow mode A.

[0107] The above relationship will be further explained with reference to Fig. 27 and Fig. 28. Fig. 27(a) to (d) are diagrams for explaining the state of the ink flow 17 in the vicinity of the ejection port portion 13b in the liquid ejection heads in the regions above and below the threshold line 20 shown in Fig. 26. Fig. 28 is a diagram for explaining whether the flow is in flow mode A or flow mode B for liquid ejection heads of various shapes. In Fig. 28, black circles indicate liquid ejection heads in flow mode A, and x marks indicate liquid ejection heads in flow mode B.

[0108] Fig. 27(a) shows the ink flow in a liquid ejection head with a shape of H 3 μm, P 9 μm, and W 12 μm, and a judgment value J of 1.93, which is greater than 1.7. In other words, the example shown in Fig. 27(a) is flow mode A. This head corresponds to point A in Fig. 28.

[0109] Figure 27(b) shows the ink flow in a liquid ejection head with a shape of H 8 μm, P 9 μm, and W 12 μm, where the judgment value is 1.39, which is smaller than 1.7. In other words, this flow is flow mode B. This head corresponds to point B in Figure 28.

[0110] Figure 27(c) shows the ink flow in a liquid ejection head with a shape of H 6 μm, P 6 μm, and W 12 μm, where the judgment value is 2.0, which is greater than 1.7. In other words, this flow is flow mode A. And this head corresponds to point C in Figure 28.

[0111] Finally, Fig. 27(d) shows the ink flow in a liquid ejection head with a shape of H 6 μm, P 6 μm, and W 6 μm, and a judgment value of 1.0, which is smaller than 1.7. In other words, this flow is flow mode B. And this head corresponds to point D in Fig. 28.

[0112] 26, it is possible to distinguish between liquid ejection heads that operate in flow mode A and liquid ejection heads that operate in flow mode B. In other words, liquid ejection heads for which the judgment value J of equation (2) is greater than 1.7 operate in flow mode A, and the ink flow 17 has a positive velocity component at least at the center of the ink interface 13a.

[0113] Next, a comparison of the ejection speeds of ink droplets ejected from a liquid ejection head that generates flow mode A (head A) and a liquid ejection head that generates flow mode B (head B) will be described.

[0114] 29(a)-(b) are graphs showing the relationship between the number of shots (number of ejections) and the ejection speed at that time after a certain period of pause following ejection from a liquid ejection head in each flow mode.

[0115] FIG. 29(a) shows the relationship between the number of shots and the ejection speed when ejecting pigment ink containing 20% ​​or more by weight of solids with an ink viscosity of about 4 cP at the temperature at the time of ejection using head B. As shown in the figure, even if an ink flow 17 exists, the ejection speed decreases until about the 20th shot depending on the pause time. FIG. 29(b) shows the relationship between the number of shots and the ejection speed when ejecting the same pigment ink as in FIG. 29(a) using head A, and the ejection speed does not decrease from the first shot after the pause. In this experiment, ink containing 20% ​​or more by weight of solids was used, but the concentration does not limit the present invention. Although it depends on the ease of dispersion of solids in the ink, the effect of mode A is clearly seen when ejecting ink with a solid content of 8% by weight or more (8 wt% or more).

[0116] In this way, in a head that generates flow mode A, it is possible to suppress a decrease in the ink droplet ejection speed even when using ink that is prone to a decrease in ejection speed due to increased viscosity caused by evaporation of the ink from the ejection ports.

[0117] As for whether the flow of the ink flow 17 in the ejection port becomes flow mode A or flow mode B, under normal circumstances, the relationship between P, W, and H related to the shape of the flow path, etc., as described above, has a dominant effect. In addition to these conditions, for example, conditions such as the flow velocity of the ink flow 17, the viscosity of the ink, and the width of the ejection port 13 in a direction perpendicular to the flow direction of the ink flow 17 (the length of the ejection port in a direction perpendicular to W) have an extremely small effect compared to P, W, and H. Therefore, the flow velocity of the ink and the viscosity of the ink may be appropriately set according to the required specifications of the liquid ejection head (inkjet recording device) and the environmental conditions in which it is used. For example, the flow velocity of the ink flow 17 in the flow path 24 is 0.1 to 100 mm / s, and the viscosity of the ink is 30 cP or less at the temperature during ejection. In addition, if the amount of ink evaporation from the ejection port increases significantly due to environmental changes during use, the flow rate of the ink flow 17 can be appropriately increased to make it flow mode A. If a liquid ejection head in flow mode B is used, no matter how much the flow rate is increased, it will not become flow mode A. In other words, whether the mode is Mode A or Flow Mode B is determined not by the ink flow speed or ink viscosity, but by the relationship between H, P, and W related to the shape of the liquid ejection head described above. Furthermore, among the various liquid ejection heads that are in Flow Mode A, liquid ejection heads in which H is 20 μm or less, P is 20 μm or less, and W is 30 μm or less are particularly preferable, as they enable recording with higher resolution.

[0118] As described above, the liquid ejection head that generates the flow mode A can make the ink in the ejection port portion 13b, particularly the ink near the ink interface, flow out to the flow path 24 by the ink flow 17 that reaches the vicinity of the ink interface 13a with a positive velocity component. Therefore, it is possible to suppress the stagnation of the ink inside the ejection port portion 13b. This makes it possible to reduce the increase in the coloring material concentration of the ink in the ejection port portion even when the ink evaporates from the ejection port. In addition, in this embodiment, the ink ejection operation is performed in a state in which the ink is flowing in the flow path 24 as described above. Therefore, the ink is ejected in a state in which the ink flows from the flow path 24 (pressure chamber 23) into the ejection port portion 13b, reaches the ink interface, and then returns to the ink flow path. As a result, even in a recording operation pause state, the increase in the coloring material concentration inside the ejection port portion 13b is always reduced, so that the first ejection after the recording operation pause can be performed well and the occurrence of color unevenness can be reduced. However, the present invention is also applicable to a liquid ejection head that performs an ink ejection operation in a state in which the ink flow in the ink flow path 24 is stopped. After the recording operation is stopped, a circulating flow may be generated in the ink flow path to reduce the increase in viscosity of the ink inside the ejection port portion 13b, and the ink may be ejected after the circulating flow is stopped.

[0119] (Third embodiment) FIG. 30 is a diagram showing the state of the ink flow in the liquid ejection head according to the third embodiment of the present invention, and the same parts as those in the above-mentioned embodiment are denoted by the same reference numerals and the description thereof is omitted. As shown in FIG. 30, in this embodiment, the height of the flow path 24 in the vicinity of the ejection port 13 (ejection port portion 13b) is lower than the height of the flow path 24 in other portions. Specifically, the height H of the flow path 24 on the upstream side of the communication portion between the flow path 24 and the ejection port portion 13b in the flow direction of the liquid in the flow path is lower than the height of the flow path 24 at the communication portion between the flow path 24 and the liquid supply path 18 (see FIG. 22). In this embodiment as well, by setting H, P, and W so as to satisfy the formula (1), at least a part of the ink flow 17 can be returned to the flow path 24 after reaching a position 1 / 2 or more of the ejection port portion 13b in the direction from the pressure chamber 23 toward the ink interface 13a. Furthermore, in this embodiment as well, by setting H, P, and W so as to satisfy the formula (2), the flow mode A is obtained.

[0120] In this embodiment, the flow path height from the communication part between the flow path 24 and the liquid supply path 18 to the vicinity of the ejection port, and the flow path height from the vicinity of the ejection port to the liquid recovery path 19 are relatively high, so that the flow path resistance in those parts can be reduced. In addition, by relatively reducing the flow path height H in the vicinity of the ejection port 13b, a liquid ejection head of flow mode A described in the second embodiment can be obtained. Normally, if the height of the flow path 24 is lowered overall to satisfy formula (2), the flow path resistance from the liquid supply path 18 or the liquid recovery path 19 to the ejection port 13 increases, and the speed at which ink is refilled (refill speed) due to the ejection may decrease. Therefore, as in the configuration of this embodiment, by lowering the height of the flow path in the vicinity of the ejection port 13 below the height of the flow path in the other parts, it is possible to secure the necessary refill speed while satisfying formula (1) or formula (2). This makes it possible to suppress the increase in viscosity of the ink at the ejection port and achieve high-speed recording (improved throughput).

[0121] (Fourth embodiment) FIG. 31 is a diagram showing the state of the ink flow of the ink flowing in the liquid ejection head according to the fourth embodiment of the present invention. In FIG. 31, a recess 13c is formed around the ejection port 13 on the surface of the orifice plate 12. That is, the ejection port 13 is formed in the recess (the bottom surface of the recess 13c) formed in the orifice plate. In the normal state and in the stationary state when a circulating flow is generated, the ink meniscus (ink interface 13a) is formed on the boundary surface between the ejection port 13 and the bottom surface of the recess 13c. In the embodiment, by setting H, P, and W to satisfy the formula (1), at least a part of the ink flow 17 can be returned to the flow path 24 after reaching a position of 1 / 2 or more of the ejection port portion 13b in the direction from the pressure chamber 23 toward the ink interface 13a. Furthermore, in the configuration of the embodiment, by setting H, P, and W to satisfy the formula (2), the flow mode A is obtained. In this embodiment, P in formulas (1) and (2) is the length of the ejection port portion, that is, the length from the portion where the ink meniscus is formed to the flow path 24 as shown in Fig. 31. That is, the thickness of the orifice plate 12 is thinner in the vicinity of the portion contacting the ejection port 13 than in other portions. Specifically, the thickness of the orifice plate 12 in the vicinity of the ejection port 13 is thinner than the thickness of the orifice plate at the connection portion between the flow path 24 and the liquid supply path 18 (see Fig. 22).

[0122] In this embodiment, the thickness P of the orifice plate 12 near the discharge port portion 13b can be reduced while keeping the thickness of the orifice plate 12 relatively thick for the entire head. Normally, when the length P of the discharge port portion is shortened to satisfy formulas (1) and (2), the thickness of the entire orifice plate becomes thin, and the strength of the orifice plate decreases. However, according to the configuration of this embodiment, in addition to the effects of the first and second embodiments, the strength of the orifice plate 12 as a whole can be ensured.

[0123] Fifth embodiment FIG. 32 is a diagram showing the state of the ink flow in the liquid ejection head according to the fifth embodiment of the present invention. As shown in FIG. 32, the height of the flow path 24 is lower near the connection with the ejection port 13 than at other points, and a recess 13c is formed around the ejection port 13 on the surface of the orifice plate 12. As a specific configuration, the height H of the flow path 24 on the upstream side of the communication part between the flow path 24 and the ejection port part 13b in the flow direction of the liquid in the flow path is lower than the height of the flow path 24 near the communication part between the flow path 24 and the liquid supply path 18 (see FIG. 22). In the configuration of this embodiment, as in the fourth embodiment, in the normal state and in the stationary state when a circulating flow is generated, the meniscus (ink interface 13a) of the ink is formed at the boundary surface between the ejection port 13 and the bottom surface of the recess 13c.

[0124] In this embodiment, the flow path height H in the vicinity of the discharge port can be reduced while maintaining low flow path resistance from the liquid supply path 18 or the liquid recovery path 19 to the discharge port 13, and further, the length P of the discharge port portion 13b can be shortened. Normally, if the height of the flow path 24 is made lower near the connection with the discharge port 13 than at other points, the thickness of the orifice plate 12 in the vicinity of the discharge port 13 increases accordingly, and the length P of the discharge port 13 becomes longer. In contrast, the configuration of this embodiment can ensure the necessary refill speed in addition to the effects of the first and second embodiments.

[0125] Sixth embodiment FIG. 33 is a diagram showing the state of the ink flow of the ink flowing in the liquid ejection head according to the sixth embodiment of the present invention. As shown in FIG. 33, the liquid ejection head according to this embodiment has a step portion at the communication portion between the flow path 24 and the ejection port portion 13b. In this embodiment, the portion from the ejection port 13 to the portion where the step portion is formed is the ejection port portion 13b, and the ejection port portion 13b is connected to the flow path 24 through a portion (a part of the flow path) having a larger diameter than the ejection port portion 13b. Therefore, P, W, and H in this embodiment are defined as shown in the figure. In this liquid ejection head, by setting H, P, and W so as to satisfy the formula (1), at least a part of the ink flow 17 can be returned to the flow path 24 after reaching a position 1 / 2 or more of the ejection port portion 13b in the direction from the pressure chamber 23 toward the ink interface 13a. Furthermore, by setting H, P, and W so as to satisfy the formula (2), the flow mode A can be generated.

[0126] In this way, by configuring the portion from the flow path toward the discharge port in a multi-stage configuration, it is possible to relatively reduce the flow resistance in the direction from the energy generating element 15 toward the discharge port 13. In this way, the configuration of this embodiment improves discharge efficiency, and in addition to the effects of the first and second embodiments, it is preferable when discharging small droplets of, for example, 5 pl or less.

[0127] Seventh embodiment FIG. 34 is a diagram showing the state of the ink flow of the ink flowing in the liquid ejection head according to the seventh embodiment of the present invention. As shown in FIG. 34, the ejection port 13b communicating between the ejection port 13 and the flow path 24 is a truncated cone. Specifically, the opening diameter of the ejection port 13b on the flow path side is larger than the opening diameter of the ejection port 13 on the ejection port 13 side, and the side wall is tapered. With this configuration, the flow resistance in the direction from the energy generating element 15 to the ejection port 13 can be made relatively small, and the ejection efficiency can be improved. In the embodiment, by setting H, P, and W to satisfy the formula (1), at least a part of the ink flow 17 can be returned to the flow path 24 after reaching a position of 1 / 2 or more of the ejection port 13b in the direction from the pressure chamber 23 to the ink interface 13a. Furthermore, in the embodiment, by setting H, P, and W to satisfy the formula (2), the flow mode A can be generated. In this embodiment, W in formulas (1) and (2) defines the length of the communicating portion between the discharge port 13b and the flow path 24 as W, as shown in Fig. 34. In addition to the effects of the first embodiment, the configuration of this embodiment is preferable when discharging small droplets of, for example, 5 pl or less.

[0128] Eighth embodiment 35(a) and (b) are diagrams showing two examples of the shape of the ejection port of the liquid ejection head according to the eighth embodiment of the present invention, and show plan views (schematic diagrams) seen from the direction in which liquid is ejected from the ejection port 13. The shape of the ejection port 13 in this embodiment is such that protrusions 13d extending toward the center of the ejection port are formed at opposing positions. The protrusions 13d extend continuously from the outer surface of the ejection port 13 to the inside of the ejection port portion 13b. Even in shapes having these protrusions, by setting H, P, and W to satisfy formula (1), at least a part of the ink flow 17 can be returned to the flow path 24 after reaching a position at least half the ejection port portion 13b in the direction from the pressure chamber 23 toward the ink interface 13a. Furthermore, by setting H, P, and W to satisfy the above-mentioned formula (2), the flow mode A can be generated.

[0129] The ejection port in the example shown in Fig. 35(a) has a protrusion 13d that protrudes in a direction intersecting the flow of liquid in the flow channel 24, while the ejection port in the example shown in Fig. 35(b) has a protrusion 13d that protrudes in the direction of the ink flow. By forming such protrusions on the ejection port 13, the meniscus formed between the protrusions 13d can be more easily maintained than the meniscus in other parts of the ejection port, and the tail of the ink droplet extending from the ejection port can be cut off at an earlier timing. This makes it possible to suppress the generation of mist, which is a small droplet that occurs in association with the main droplet.

[0130] Figures 44 and 45 are diagrams showing a more specific configuration of the liquid ejection head in Figure 35(B). The specific dimensions of each part in this embodiment are H=16 μm, P=6 μm, W=22 μm with a judgment value J=2.6 in Figure 44, and H=5 μm, P=5 μm, W=20 μm with a judgment value J=4.3 in Figure 45.

[0131] Ninth embodiment 36 to 38 are diagrams for explaining a liquid ejection head according to a ninth embodiment of the present invention. This embodiment is an embodiment that improves the second to eighth embodiments, and does not limit the above-mentioned embodiments. The relationship between the amount of evaporation of ink moisture and the like from the ink interface 13a formed at the ejection port 13 and the flow rate of the ink flow 17 will be described with reference to FIG. 36 and FIG. 37. When the amount of evaporation from the ink interface 13a is relatively large due to environmental conditions, etc., and the ratio of the flow rate of the ink flow 17 to the amount of evaporation is small, as shown in FIG. 36(a), the ink flow in the ejection port portion 13b becomes dominated by the flow toward the ink interface 13a. The state in which the ink flow in the ejection port portion 13b becomes dominated by the flow toward the ink interface 13a in this way is hereinafter referred to as state D. In state D, as shown in FIG. 37(a), the coloring material concentration in the ejection port portion becomes relatively high due to evaporation. On the other hand, when the ink flow 17 is sufficient for the amount of evaporation even if the amount of evaporation is large, the flow of the ink flow 17 in the ejection port portion 13b becomes dominant over the flow toward the ink interface 13a as shown in FIG. 36(b). The state in which the flow of the ink flow 17 in the ejection port portion 13b becomes dominant over the flow toward the ink interface 13a as shown in FIG. 37(b) is hereinafter referred to as state C. As a result, the colorant concentration in the ejection port portion becomes relatively low as shown in FIG. 37(b). That is, state C can be achieved in a liquid ejection head that satisfies the formulas (1) and (2) described in the first and second embodiments. That is, even if the amount of evaporation from the ink interface 13a increases due to environmental conditions during use of the liquid ejection head, state C can be achieved by sufficiently increasing the flow rate of the ink flow 17. This makes it possible to further suppress the ink that has undergone a change in colorant concentration due to the evaporation of ink from the ejection port from staying in the ejection port portion 13b.

[0132] As a comparative example, a liquid ejection head that does not satisfy formula (2) will be described. In this example, no matter how much the flow rate of the ink flow 17 is increased, flow mode A does not occur. In other words, in order to achieve flow mode A, it is necessary to satisfy formula (2).

[0133] Here, even in the case of a liquid ejection head that satisfies formula (2), increasing the amount of ink flow 17 increases the pressure loss accordingly. For this reason, it is necessary to increase the pressure difference between the common supply path 211 and the common recovery flow path 212 (see Figs. 2 and 3). In addition, the pressure difference to each ejection port in the liquid ejection head increases, making it difficult to make the ejection characteristics uniform. From these viewpoints, therefore, it is desirable to make the flow rate of ink flow 17 as small as possible.

[0134] Therefore, in a liquid ejection head in flow mode A, an example of the flow velocity condition of the ink flow 17 for achieving state C will be described below.

[0135] In this embodiment, in a liquid ejection head with H of 3 to 6 μm, P of 3 to 6 μm, and W of 17 to 25 μm, the following conditions are set to prevent ink that has changed in colorant concentration due to evaporation from staying inside the ejection port portion 13b. That is, the relationship between the average flow velocity V17 of the ink flow 17 and the average evaporation flow velocity V12 from the ink interface 13a is expressed by the following formula (5). V17≧27×V12 Formula (5)

[0136] Studies by the present inventors have revealed that a liquid ejection head that satisfies formula (5) is in state C. A liquid ejection head with H of 3 to 6 μm, P of 3 to 6 μm, and W of 17 μm or more satisfies formula (2), and can be put into state C by circulating a sufficient amount of ink relative to the amount of evaporation. The above formula (5) shows the circulation flow speed required to achieve state C. Formula (5) will be explained with reference to FIG. 38.

[0137] FIG. 38 is a diagram showing the relationship between the evaporation rate and the circulation flow rate in state C, and the evaporation rate and the circulation flow rate in state D. The horizontal axis of FIG. 38 is the evaporation rate V12, and the vertical axis is the flow rate V17 of the ink flow due to circulation, and data for each flow mode is shown for each of the four shapes of liquid ejection heads 1 to 4. For liquid ejection head 1, H is 6 μm, P is 6 μm, W is 17 μm, and the judgment value J is 2.83. For liquid ejection head 2, H is 6 μm, P is 6 μm, W is 21 μm, and the judgment value J is 3.5. For liquid ejection head 3, H is 5 μm, P is 3 μm, W is 21 μm, and the judgment value J is 5.88. For liquid ejection head 4, H is 5 μm, P is 3 μm, W is 25 μm, and the judgment value J is 7.0.

[0138] From FIG. 38, it can be seen that in a certain liquid ejection head, the circulation flow velocity V17 required to change the state to state C, not state D, is proportional to the evaporation flow velocity V12. It can also be seen that the smaller the judgment value J, the higher the circulation flow velocity required to change the state to state C. Furthermore, in the case of a liquid ejection head with H of 3 to 6 μm, P of 3 to 6 μm, and W of 17 to 25 μm, and with the smallest judgment value J of 2.83 (liquid ejection head 1), it can be seen that state C is achieved when the circulation flow velocity is 27 times or more the evaporation flow velocity. Therefore, in a liquid ejection head with H of 3 to 6 μm, P of 3 to 6 μm, and W of 17 μm or more, state C is achieved by satisfying formula (5), and it is possible to suppress the retention of ink in the ejection port portion 13b, in which the color material concentration has changed due to evaporation. In other words, it is possible to reduce the occurrence of color unevenness in an image due to liquid evaporation from the ejection port 13. For example, in the experiments conducted by the inventors of the present application, the amount of evaporation from a circular nozzle with W of 18 μm was about 140 pl / s, and the average evaporation flow rate was about 1.35×10 -4 In this case, the average circulation flow velocity is required to be about 0.0036 m / s or more. The evaporation amount here refers to the amount of evaporation when the ink concentration at the ejection port portion 13b does not change.

[0139] Similarly, in a liquid ejection head with H of 8 μm, P of 8 μm, W of 17 μm, and a judgment value J of 2.13, state C is achieved by making the average flow velocity V17 of the ink flow 17 50 times or more the average evaporation flow rate V12 from the ink interface 13a. Therefore, in a liquid ejection head with H of 8 μm or less, P of 8 μm or less, and W of 17 μm or more, state C can be achieved by making the average flow velocity V17 of the ink flow 17 50 times or more the average evaporation flow rate V12 from the ink interface 13a. This makes it possible to prevent ink that has undergone a change in color material concentration due to evaporation from accumulating in the ejection port portion 13b. As a result, it is possible to reduce the occurrence of color unevenness in an image due to liquid evaporation from the ejection port 13. Similarly to the above, when the amount of evaporation from a circular ejection port with W of 18 μm is about 140 pl / s, an average circulation flow velocity of about 0.0067 m / s or more is required.

[0140] Similarly, in a liquid ejection head with H of 15 μm, P of 7 μm, W of 17 μm, and a judgment value J of 1.87, state C can be achieved by making the average flow velocity V17 of the ink flow 17 50 times or more the average evaporation flow rate V12 from the ink interface 13a. Therefore, in a liquid ejection head with H of 15 μm or less, P of 7 μm or less, and W of 17 μm or more, state C can be achieved by making the average flow velocity V17 of the ink flow 17 100 times or more the average evaporation flow rate V12 from the ink interface 13a. Similarly to the above, when the evaporation rate from a circular ejection orifice with W of 18 μm is about 140 pl / s, an average circulation flow velocity of about 0.0135 m / s or more is required.

[0141] Next, the configuration of a different liquid ejection head will be described. This liquid ejection head is a liquid ejection head in which H is 14 μm or less, P is 12 μm or less, W is 17 μm or more, and H, P, and W satisfy formula (2). This liquid ejection head satisfies the following formula (6) to prevent ink that has undergone a change in colorant concentration due to evaporation of ink from the ejection port from accumulating in the ejection port portion 13b. In other words, the average flow velocity V17 of the circulating flow 17 and the average evaporation flow velocity V12 from the ink interface 13a satisfy the following formula (6). V17≧900×V12 Formula (6)

[0142] In a liquid ejection head with H of 12.3 μm, P of 9 μm, and W of 17 μm (determination value J is 1.7), state C can be achieved by making the average flow velocity V17 of the ink flow 17 900 times the average evaporation flow velocity V12 from the ink interface 13a. Similarly, in a liquid ejection head with H of 10 μm, P of 10 μm, and W of 17 μm (determination value J is 1.7), state C can be achieved by making the average flow velocity V17 of the ink flow 17 900 times the average evaporation flow velocity V12 from the ink interface 13a. Similarly, in a liquid ejection head with H of 8.3 μm, P of 11 μm, and W of 17 μm (determination value J is 1.7), state C can be achieved by making the average flow velocity V17 of the circulating flow 17 900 times the average evaporation flow velocity V12 from the ink interface 13a. Similarly, in a liquid ejection head with H of 7 μm, P of 12 μm, and W of 17 μm (judgment value J of 1.7), state C can be achieved by making the average flow velocity V17 of the circulating flow 17 900 times the average evaporation flow velocity V12 from the ink interface 13a.

[0143] Therefore, a liquid ejection head in which H is 14 μm or less, P is 12 μm or less, W is 17 μm or more, and H, P, and W satisfy formula (2) is in state C by satisfying formula (6).

[0144] Regarding the ninth embodiment described above, the conditions for state C can be summarized as follows:

[0145] H is 14 μm or less, P is 12 μm or less, W is 17 μm or more and 30 μm or less, and the flow velocity of the liquid in the flow path is 900 times or more the evaporation speed from the discharge port.

[0146] Alternatively, H is 15 μm or less, P is 7 μm or less, W is 17 μm or more and 30 μm or less, and the flow rate of the liquid in the flow path is 100 times or more the evaporation rate from the discharge port.

[0147] Alternatively, H is 8 μm or less, P is 8 μm or less, W is 17 μm or more and 30 μm or less, and the flow rate of the liquid in the flow path is 50 times or more the evaporation rate from the discharge port.

[0148] Alternatively, H is 3 μm or more and 6 μm or less, P is 3 μm or more and 6 μm or less, W is 17 μm or more and 30 μm or less, and the flow velocity of the liquid in the flow path is 27 times or more the evaporation speed from the discharge port.

[0149] Here, the above-mentioned liquid flow velocity regulation means that the range in which state C will be reached even for the shape that is least likely to reach state C within each head shape range, and that for other shapes within each head shape range, state C may be reached at a smaller flow velocity.

[0150] (Tenth embodiment) 39 to 42 are diagrams illustrating a liquid ejection head according to a tenth embodiment of the present invention, and this embodiment relates to the relationship between the following two types of characteristics and the shape of a flow path including an ejection port. Characteristic 1) Flow mode of ink flow Characteristic 2) Droplets ejected from the ejection port In particular, the relationship with the above characteristics will be described using the following three types of ejection port shapes with an ejection volume Vd of 5 pl as examples. Channel shape A) H=14μm, P=11μm, W=16μm (J=1.34) Flow path shape B) H=09μm, P=11μm, W=18μm (J=1.79) Channel shape C) H=14μm, P=06μm, W=18μm (J=2.30) Where: H: Height of the flow channel 24 on the upstream side in the flow direction of the liquid in the flow channel 24 (see FIG. 22) P: length of the discharge port portion 13b in the direction in which liquid is discharged from the discharge port 13 (see FIG. 22) W: Length of the discharge port 13b in the direction of liquid flow in the flow path 24 (see FIG. 22) Z: Effective length of the inscribed circle of the outlet 13 However, since the shape of the discharge port 13 is circular (see FIG. 22), the effective diameters Z and W of the inscribed circle of the discharge port 13 are equal.

[0151] Moreover, the reason why a Vd of 5 pl is used as an example is that when the ejection volume is large, multiple main droplets and multiple droplets (hereinafter also referred to as satellites) tend to occur, which leads to deterioration of image quality.

[0152] Figures 39(a) to (c) are diagrams showing the flow modes of three flow path shapes A to C, and Figure 40 is a contour map showing the judgment value J when the outlet diameter is changed so that the discharge volume Vd is approximately 5 pl, with H on the horizontal axis and P on the vertical axis.

[0153] The flow path shape A has a judgment value J=1.34, and generates a flow mode B as shown in FIG. 39(a). The dimension (hereinafter also referred to as OH) of the flow path shape A obtained by adding H and P is 25 μm, but in order to increase the judgment value J, it is necessary to reduce H or P and lower OH. In the case of OH=20 μm, the flow path shape B in which only H is reduced has a judgment value J=1.79, and generates a flow mode A as shown in FIG. 39(b). The flow path shape C in which only P is reduced has a judgment value J=2.30, and similarly generates a flow mode A as shown in FIG. 39(c). In addition, the flow path shape C allows the ink flow to easily enter the inside of the ejection port more easily than the flow path shape B, and can further suppress the stagnation of ink inside the ejection port portion 13b. Therefore, the following shapes can be mentioned with respect to the flow mode of the ink flow. Shape characteristic (1): For equal OH, it is preferable to make P smaller (see FIG. 40). Shape characteristic (2) It is preferable to reduce OH (see FIG. 40).

[0154] 41(a) to (c) are diagrams showing the results of observing the discharged droplets from each of the three types of flow path shapes A to C. Fig. 42 is a contour map showing the calculated values ​​of the time it takes for the air bubbles to communicate with the atmosphere (hereinafter also referred to as Tth) when the discharge port diameter is changed so that the discharge volume Vd is approximately 5 pl, with H on the horizontal axis and P on the vertical axis.

[0155] 41(a) and (c) show the case where two types of discharged droplets, a main droplet and a satellite, are generated. On the other hand, FIG. 41(b) shows the case where a main droplet and multiple satellites are generated. Flow path shape A has Tth=5.8 us, and flow path shape C has Tth=4.5 us, whereas flow path shape B has Tth=3.8 us, which is smaller (see FIG. 42). In general, when the discharge amount Vd is large as in this embodiment, multiple satellites are generated when Tth is small. This is because when Tth is small, that is, when communication with the atmosphere is promoted, a long and thin tail is likely to occur, and multiple nodes are generated due to the instability of the tail. As a result, the long and thin tail cannot be contracted into one, and multiple satellites are generated as shown in FIG. 41(b). Therefore, the following can be mentioned for suppressing satellites. Shape characteristic (3): For equal OH, it is preferable to make P smaller (see Figure 42) Shape characteristic (4) It is preferable to increase OH (see Figure 42)

[0156] From the above, the increase in the judgment value J required to suppress the ink retention in the ejection port portion 13b is as follows: Shape characteristics A) OH reduction, Shape characteristic B) For equal OH, P should be smaller than H; In addition, the increase in the threshold Tth required to suppress the main droplet and satellite droplets requires: C) Increasing shape characteristics; Shape characteristic D) For equal OH, P should be smaller than H; Since shape characteristic A) and shape characteristic C) are contradictory characteristics, it is desirable to satisfy the following conditions to achieve a compatible solution. The flow mode judgment value J>1.7 and the air communication time judgment value Tth>4.0μs,

[0157] Therefore, it is preferable to set the range as shown in Fig. 42. When the judgment value Tth satisfies the above condition, the judgment value Tth in the diagram shown in Fig. 42 is as follows: Tth=0.350×H+0.227×P―0.100×Z The above shows that when H or P is small or when Z increases, Tth becomes small and multiple satellites are more likely to occur. In particular, since H is about 1.5 times more sensitive than P, for the same OH, making P smaller suppresses the reduction in Tth and can suppress the occurrence of satellites. Therefore, the above condition can be expressed by the following formula. 0.350×H+0.227×P―0.100×Z>4 Formula (7) It can be expressed as:

[0158] By setting the shape characteristics of the ejection port within the above-mentioned effective range, it is possible to achieve the circulation effect (suppression of ink retention in the ejection port portion 13b) and suppression of the occurrence of satellites when the ejection amount Vd is 5 ng.

[0159] As described above, the above-mentioned embodiments can suppress the variation in the quality of the liquid near the ejection port, and for example, can suppress the increase in ink viscosity due to the evaporation of the liquid from the ejection port and reduce color unevenness in the image. In particular, by satisfying the formula (2) described in the second embodiment, the flow mode A can be set and the retention of ink in the ejection port portion 13b can be suppressed, thereby making it possible to reduce the increase in the colorant concentration. The flow speed of the ink flowing through the flow path 24 can be appropriately set according to the conditions and environment in which the liquid ejection head is used, following the concept described in this embodiment.

[0160] The present invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0161] 13 Outlet 13a Meniscus (ink interface) 13b Discharge port 15 Energy generating elements 17 Circulating flow 23 Pressure Chamber 24 Flow Path

Claims

1. A method for supplying liquid in a liquid ejection head comprising: an ejection port for ejecting liquid; a flow path in which an energy generating element for generating energy used to eject the liquid is disposed; an ejection port portion that communicates the ejection port with the flow path; a supply flow path for causing liquid to flow into the flow path from an outside; and an outflow flow path for causing liquid to flow out from the flow path to an outside, comprising: A liquid supply method characterized in that, when liquid is supplied by flowing from the outside into the flow path through the supply flow path and flowing from the flow path to the outside through the outflow flow path, a flow of liquid is generated in which the liquid that has flowed from the flow path into the ejection outlet portion reaches a meniscus position of the liquid formed in the ejection outlet and then returns to the flow path.

2. The liquid ejection head includes a substrate and an orifice plate formed on the substrate, The discharge port is formed in the orifice plate, 2. The liquid supply method according to claim 1, wherein the supply flow path and the outflow flow path are formed in the substrate and pass through the substrate.

3. a supply port for supplying a liquid from the supply flow path to the flow path is formed in the substrate between the flow path and the supply flow path, The liquid supply method according to claim 2 , wherein a recovery port is formed in the substrate between the flow path and the outflow path for allowing liquid to flow out from the flow path to the outflow path.

4. The supply port and the recovery port are formed in a plurality of ports on the substrate, the supply flow path is connected to the plurality of supply ports, 4. The liquid supply method according to claim 3, wherein the outflow passage is connected to the plurality of recovery ports.

5. 5. The method for supplying liquid according to claim 1, wherein the liquid returning to the flow path flows to the outlet flow path.

6. The orifice plate is made of a resin, 5. The liquid supplying method according to claim 2, wherein the substrate is made of silicon.

7. 7. The method for supplying liquid according to claim 1, wherein the viscosity of the liquid flowing through the flow path is 30 cP or less, and the flow speed of the liquid is 0.1 to 100 mm / s.

8. 5. The method for supplying a liquid according to claim 2, wherein a thickness of the orifice plate in the vicinity of the ejection port is thinner than a thickness of the orifice plate at a communicating portion between the flow path and the supply flow path.

9. 5. The liquid supplying method according to claim 2, wherein a recess is formed in the orifice plate, and the ejection port is formed within the recess.

10. A height of the flow path on the upstream side of a communicating portion between the flow path and the discharge port in the flow direction of the liquid in the flow path is H; P is the length of the discharge port portion in the direction in which liquid is discharged from the discharge port, The length of the discharge port in the flow direction of the liquid in the flow channel is W, In this case, H -0.34 ×P -0.66 ×W>1.7 10. The method for supplying a liquid according to claim 1, wherein the above formula is satisfied.

11. 11. The liquid supply method according to claim 10, wherein the height H is lower than a height of the flow channel at a communicating portion between the flow channel and the supply flow channel.

12. 12. The liquid supplying method according to claim 10, wherein H is 20 μm or less, P is 20 μm or less, and W is 30 μm or less.

13. 11. The liquid supply method according to claim 10, wherein H is 14 μm or less, P is 12 μm or less, W is 17 μm to 30 μm, and the flow velocity of the flow path is 900 times or more the evaporation rate from the ejection port.

14. A liquid supply method according to claim 10, characterized in that H is 15 μm or less, P is 7 μm or less, W is 17 μm or more and 30 μm or less, and the flow velocity of the liquid in the flow path is 100 times or more the evaporation rate from the ejection port.

15. 11. A liquid supply method according to claim 10, wherein H is 8 μm or less, P is 8 μm or less, W is 17 μm to 30 μm, and the flow velocity of the flow path is 50 times or more the evaporation rate from the ejection port.

16. A liquid supply method according to claim 10, characterized in that H is 3 μm or more and 6 μm or less, P is 3 μm or more and 6 μm or less, W is 17 μm or more and 30 μm or less, and the flow velocity of the liquid in the flow path is 27 times or more the evaporation rate from the ejection port.

17. a supply means for causing a liquid to flow from the outside into the flow path through the supply flow path and for causing a liquid to flow from the flow path to the outside through the outflow flow path, 17. The liquid supplying method according to claim 1, wherein the supplying means circulates the liquid to the liquid ejection head.

18. A liquid supply method according to any one of claims 1 to 17, characterized in that the flow path includes a pressure chamber having the energy generating element therein, and the liquid in the pressure chamber is circulated between the pressure chamber and the outside via the supply flow path and the outflow flow path.

19. 19. The method for supplying a liquid according to claim 1, wherein the liquid has a solid content of 8 wt % or more.

20. 20. The liquid supplying method according to claim 1, wherein the energy generating element is a heat generating element, and bubbles generated by heating the energy generating element communicate with the atmosphere via the discharge port.

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